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Humm! IMO.. I would be very cautious in supporting this storage system. Far too many of the plastics storage systems have fail miserably causing more headaches and heartaches that one can say. First all plastic itself will break down. Some plastic material faster that others. I see nothing more than a sales pitch with very bold claims on a product that has very little technical research behind it. I would need to see more soild proof. As far as stoping zinc pest. Zinc pest starts within the medal itself and moves outward. Yes lack of oxygen will slow it some but to hault zin pest 100% ??. Putting a non clean weapond in a plastic bag in IMO asking for trouble. The gun powder residue body salts will attack plastic.Last edited by Paul R.; 04-17-2010, 04:02 PM. -
Paul,
Thanks for your reply on this subject.
First of all, these systems have been throughly tested and apporved for use by militaries world wide.
As an example, resupply of new M60 machine gun barrels are stored in this very manner direct from the manufacturer when shipped to the arsenal warehouses are stored this way. When requistioned from supplies, these are shipped to the end user then pulled from these systems for installation and use.
As a further example, we have sold similar systems to the US Navy Seal Team for cold wrap (not zipped, but cold seal film that clings to itself when pressed together) storage of their weapons systems prior and after use, and as such is fully accepted by US Naval Surface Warfare Center for that use.
Getting these people to accept anything is quite challenging!!
I don't anticipate anyone here buying in like quantites unless they have a private Army
, but for collectors who want and need the help the resource is here for them to at least review and draw their own conclusions.
Since the inhbitors in the bag lasts about 2 years, these can be dated with a marker with installation date. We always advise people who use this system not to go beyond 18 months, however I have personally stored firearms this way longer with zero ill effects.
You must remember this system is not indefinite, thus before anything can gas off, the inhibiting system looses it's efficacy for protecting the metal item stored inside the system thus the bag does not decay or gas off within that period. If any off gas is produced it is from the outer surface if at all as that surface is not coated with the inhbitor.
In the last 13 years we have not had a single claim of damage being done to militaria, weapons, parts, cameras and other metal parts stored in this manner.
if you can show me where something says otherwise, I am all ears to understand that report since this is what I do for a living.
There have been & are too may tests with results that point to the efficency & efficacy of this system.
Manufacturers such as Porche, Harley Davidson, Polaris, Chrysler, GM, Ford, NASA, Boeing, McDonnald Douglas and here you go:
http://www.cortecvci.com/Publication...rr%20Broch.pdf
Did not mention, even NASA makes use of the technology!!
If you want to view it as a sales pitch, fine & you can, for others I am sure this can be seen as a way to preserve what you have in an efficent manner.
Regarding the tests your pointing too, thankfully this manufacturer has done many, many tests as well as independent test by military systems and manufacturers world wide that can be shared to show results. We use these daily to support what we know works.
Yes, we are CORTEC distributors and have helped many, many people with problems associated with corrosion.Comment
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Hello all - This thread has the potential of being very informative thread for all forum members who have less knowledge related to preservation. But I don't want to read any endorsements to the point that some of what has been written in a post appears to selling a product. If so I will delete all the threads related to the subject. I am very interested in and I believe others are wanting to learn more from two knowledgeable forum members about this type of storing and perservation, thanks.
Somebody, after all, had to make a start. What we wrote and said is also believed by many others. They just don't dare express themselves as we did. Quote - Sophie Scholl - White Rose resistance groupComment
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Ralph,
Thank you for the frankness regarding what I think as well all Forum members would want to see, a give and take about these corrosion prevention systems for small to large objects.
I thought would in the best interest if folks would PM if they wished to go that way but Pauls reply begged for an open answer as in this business, opinions taken by thos who might not have all the information and was stated as such beg open discussion. And for the sake of the Forum, if sales do occur, I have zero issue taking a banner ad out with the Forum.
My wife and I have been providing these solutions to Hawaii Historic Arms Society members and their affliate groups many belong to.
Some of the members work here:
http://en.wikipedia.org/wiki/Fort_De...ry_Reservation
If you go to the link look closely at the upped deck just behind the palm tree and wall. You'll see a Cobra pylon and blades. We've been providing care for this bird since about 2006 or so.
Many of the members have been on these systems since about 98 -99 time frame. We were doing 2 shows a year here and consistanly educated to help resolve corrosion issues with a high number of items such as folders, Bowies, Remingtons, Colts, Lugers, Mauser, Walther, and many other known and unknown makers such as one off production with the custom knife people who live here. We have a couple three smithies and one who is a master at his styles of damascus which are waterfall style and maiden hair I believe the terms are.
Hey, I used to collect baldes years back, I was at it big with a Himmler SS, Roehm SA, Luft & Army etch, Voss, Teno High Leader and others. I got out of the blades because of corrosion and ended up with what I have now, uniforms & insignia. I have to say with each collectible realm, there is no getting away from having to work at care of a collection.
Lots of responsibility when you end up with items that run in the many tens of thousands and even withthose less there is the responsibility of leaving it in a best condition for time as well. That fact I believe is part of the catechism of collecting.
Regarding the zinc issue, zinc is a sacrifical coating, designed to corrode when left in open atmosphere. Best results with cororsion prevention for the substrate or base metal is to have at least a 6" zone of air flow. This al;lows the zinc to corrode to a state where the oxides reach insert and allow the oxides to passivate further corrroison. This of course is not what a collector wants because of what it can do to the finish and even the structure of anitem in its designed state. These things can weaken and break if there are imperfections in production as cororison likes to track along edges because there is less resistance to the flow of electrons, less area of protection because the edges are at the thousands of an inch inmeasurement.
With any type of coatings, the edges on the item is the most difficult to protect because of the thinness of the area, thus corrosion typically starts here.
If a chemical makes contact with the surface, this tends to oxide (rust) off in colors, such as greens, yellows, oranges. A lot depends on the base metal too, as the different metals made all exhaust a color in it's oxide due to the makeup of the base raw materials. There is a guide for solutions based on the base metal as this is what requires the highest degree of protection s=o understanding that goes a loing way in allowing the finish on your collectible to remain intact. After all, when metal oxides (rust) off, it spalls or grows in size, pushing the coating away due to the oxides (rust) ability to grow as the oxides (rust) bond is much greater due to a sort of elctro weldment, thus pushing your coating away (undercutting) where the coating can be bubbling along with the substrate or on it's own due to undercutting.
Going back to he chemicals, these can be as simple comiong from unguarded handling as your skin oils, sweat... and with this that is what happened to the SS Gruppenfurher insignia seen in the picture in the bag, sweat hit the insignia after a show when packing or unpacking is my best estimate. Hawaii is hot, moving stuff around, then unpacking an laying away in a case, a drop of sweat from my forehead fell into a section of the insigna. This estiumate is based on remebring when it happened, I was not wearing a doo rag or one of the under armor skull caps. I highly recommend for collectors to understand this, sweat from your forehead if occuring can and will come into contact with your collectible at the percise time your Guiness becomes too cold to drink!!
From that sweat the aluminum began oxidizing. I was freaked out because of the fact this matched set is quite rare, was aquired in el primo superb condition. I've looked for years and was fortunate to acquire such a fine set, and then this happens.Seeing the loss hapening in front of my eyes I had to do something. Sucks, but that is reality.
You'll have tio looke close to find it, so if you can't, advise and I will improve the image....hey, it is all about training so stop your whining you.......like gunny says in mail call....maggot!!!
So far we have zinc pest or oxidation on the metal substrate to the allowance of oxugen to strile the surfaces.
WIth an arm shield comes heightened awareness that these peices can be extremely difficult to preserve once this process starts, these small bags will resolve the oxygen issue, allow inhbitors to attach by their anodic/cathodic charge.
With the SS GRP insignia, I used a lquid chemical that reduces aluminum oxidation 2X. This was applied with Q tip. After each treatment, a little more cropped up becuse what is happenign I am workign togoet th eoxide at the charged corrosion cell. Once the oxidation was removed, the insignia was store din the blue bag, onl;y taken ut for short look, and the recent images. I can still display this if I want, but this requires reinsertion into thebag to prevent the oxide attack from worsening. If you have a digital camera I highly suggest that you photo document at close up your top items in your collection. By review of these and images annually you'll have sound proof of condtiion.
Why rely on memory when the system works? These principles are used by DOD Army as our team performs this routine daily on a tactical fleet here to the tune of thousands of pieces.
Yes, the difference is insignia to a 2.5 or 5 ton truck, however, the principals remain the same.
Enough of lecture, questions?
I could type a lot more here, my wife is begging for a ride on the Harley so it is time to go. The Harley has 76 K on it, and that started as a corrosion anchor too in some select areas. It is under CONTROL or what DoD refers to CPAC, COrrosion Prevention and Control
The corrosion on my 02 Vrod is not ultimately defeated because I use the bike so frequently. That being said, there a few bikes here on Oahu with that many miles on it in the condition this one is in.
Solid corrosion prevention comes with understanding corrosion principals,and then applying that knowledge fully understnading that one cannot forgive or leave out assessing what you've done with results on a scheduled frequency for your zone of corrosion.
" The Cost of Corrosion"
http://www.corrosioncost.com/
This was commissioned by Congress and done twice so far with the help of NACE, the National Association of Corrosion Engineers. if your going to read this, please prior to take a stab at your guess of this and let us know how far off or close you were.
Hey, if my spelling is off, it is Sunday.....
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IMO There are many unanswered questions here that are not being address. Just a few point unaddressed. Plastic is an oil based product. It will self destruct. It has been studied that chemicals will advanced this problem. Your quote“With the SS GRP insignia, I used a lquid chemical that reduces aluminum oxidation 2X. This was applied with Q tip. After each treatment, a little more cropped up becuse what is happenign I am workign togoet th eoxide at the charged corrosion cell. Once the oxidation was removed, the insignia was store din the blue bag, onl;y taken ut for short look, and the recent images” Whoa! add a chemical to an artifact to stop corrosion. Museums that I work with cringe adding a chemical to an artifact to stop corroriosn. What type of chemical is this? What's the long term effect on this? Why would you leave a chemical residue on a priceless artifact that you spent at lot of money on and searched for a long time for. IMHO I don't see any form of conservation here what so ever. I see no solid proof of anything concrete about your claims. Sorry it seem all hear sayLast edited by Paul R.; 04-18-2010, 09:44 PM.Comment
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Originally posted by Paul R. View Post
Yes Paul, your right, museum personnel would cringe. So I am left with leaving the artifact to destruction by corrosion? <O
<O
What is your proposed educated alternative?
Could you please refrain from using the words here say, instead, please enlighten everyone on your technique to prevent active aluminum oxidation from growing and destroying bullion insignia when these oxides are present.
<O
I have a lot of, how should I say, feedback from curators, sometimes quite funny in fact and at other times prove enlightening as the subject should be give and take.
<O
I'll admit I've walked away from discussion with curators when I hear about not doing anything and leaving the artifact to perish to time and corrosion. And believe me, there are many of this breed out there.<O
<O
I sincerely hope you are not thinking allowing that to occur.<O
<O
By the way, preservation techniques have in some cases been discussed with curators from West Point on visit here about corrosion issues. They are all for ways to mitigate corrosion and in fact; many techniques come from people willing to run tests such as these to show what can happen. Frankly, I have no problem with doing so on my own collection, someone has to do field testing do you not agree?
<O
Paul, please, this is not a priceless artifact. There are some of these insignia around so priceless artifact to me would be the Crown Jewels <?xml:namespace prefix = v ns = "urn:schemas-microsoft-com:vml" /><v:shapetype id=_x0000_t75 class=inlineimg title=tongueout alt="" smilieid="39" stroked="f" filled="f" path="m@4@5l@4@11@9@11@9@5xe" src="images/smilies/tongue.gif" border="0" v:shapetype o<>from some kingdoms throne!!<v:shape style="WIDTH: 12pt; HEIGHT: 12pt; VISIBILITY: visible; mso-wrap-style: square" id=Picture_x0020_2 alt="http://dev.wehrmacht-awards.com/forums/images/smilies/wink.gif" type="#_x0000_t75" o:spid="_x0000_i1026"> <v:imagedata src="file:///C:\Users\RICHMO~1\AppData\Local\Temp\msohtmlclip1\ 01\clip_image002.gif" o:title="wink"></v:imagedata></v:shape></v:shapetype>
<v:shapetype class=inlineimg title=tongueout alt="" smilieid="39" stroked="f" filled="f" path="m@4@5l@4@11@9@11@9@5xe" src="images/smilies/tongue.gif" border="0" v:shapetype o<>
<O</O<O
The chemical used is produced to clean aluminum of aluminum oxides when the white rust or aluminum oxide is present. After ridding the aluminum of the active corrosion the charged amine carboxylate attaches anodically and cathodically to the same on the metal, sinks to 90 nanometers goes from crystal to film should oxygen/humidity occur to protect further than chlorides can travel and many other chemicals that may cause corrosion to occur.
<O
The other subject "what is the long term effect?" The chemical lasts about 24 months or so and exhausts. The inhibitor does have a UV tracker in it to show that the inhibitor is active. This chemical can be acquired without the UV tracker if one wanted, but due to the nature of where the product is typically used (CORTEC VpCI 238 Electronic Cleaner and Inhibitor) a High Intensity UV lamp can be used to show efficacy or in the case of "how long-term wise does this last". Many applications are quite large and in the instance where hand sprays used the High Intensity UV indicator shows where holidays or voids are present in application.
<O
Of course, one does not use a shotgun approach when a focused application is required in sensible quantity such as what a Q tip can provide.
<O
<O
Since I did not have to ask anyone about what I did, it is my insignia and investment, the results of this test are based on concrete evidence that the white oxides were removed. If one wants to doubt the claim, go for it!!
Since this incident occurred several years back, and with this treatment corrosion has been abated & the stability of the insignia is stable. You have the images to see.
<O
Can you see where the oxides are present? Can you see the open fabric thread that the aluminum was woven into?
<O
The amount of product used on this was miniscule, removal was performed with dry Q tip after allowing about a 30 second touch to the oxides again each 2X.
<O
Paul I strongly encourage you to do the research on your own of this because the facts are there if you dig.
<O
When we first approached the local museums with these techniques, they did not understand until someone tried. I can only say that we have come a long ways since the mid 90's with this.
<O
CORTEC is the largest manufacturer of corrosion inhibitors in the world. Their reach is very deep into the industry. R & D runs 8 - 10 million a year, at least this was up until the economic meltdown of late.
<O
Also, I am not here trying to sell anyone anything except to take a position with an open mind to evaluate on their own a system that does work.
<O
If anyone wants to sit on their hands so be it.
<O
In closing this part of testimony your honor.........<v:shape style="WIDTH: 12pt; HEIGHT: 12pt; VISIBILITY: visible; mso-wrap-style: square" id=Picture_x0020_3 alt="http://dev.wehrmacht-awards.com/forums/images/smilies/biggrin.gif" type="#_x0000_t75" o:spid="_x0000_i1025"> <v:imagedata src="file:///C:\Users\RICHMO~1\AppData\Local\Temp\msohtmlclip1\ 01\clip_image003.gif" o:title="biggrin"></v:imagedata></v:shape>the inhibitor can be tracked with X-ray Photoelectron Spectroscopy which can take a picture of the metal and can show the depth at which molecules absorb onto it. This imaging has been performed on their Migrating Corrosion Inhibitor for reinforcing steel. The chemistry is altered slightly to work with concrete but the amine carboxylate which the chemical is, is also altered slightly for many, many different uses with different types of chemicals.
<O
FYI amine carboxylate is (now I am sure this will be a hoot) a salt based chemical, not the salts with chlorides either. Because the amine carboxylate can hold a charge is how the inhibitor works. This salt of amine carboxylate is 5000 times less lethal than table salt.
<O
With this, I always will ask all to consider this, when choosing a corrosion inhibiting products, always ask how the inhibitor works.
<O
The answers usually are I don't know, to it forms a film and stops rust to it just does. And that last one really makes me laugh!
<O
See the chart which is not the best or go here:
<O
http://www.cortecvci.com/Products/Productcharts/Graph02.html
</v:shapetype>Last edited by Rich Moran; 04-19-2010, 01:45 AM.Comment
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Apology for a crappy cut and paste, but due to the size allowance of attachemnts it came out like this and I do not have time to re work all of it.
He ya go start digging if you have the time
ctp13.doc (ck) 6/30/98 1 of 20<O></O>
FUNDAMENTAL PRINCIPLES OF CORROSION<O></O>
PROTECTION WITH VAPOR PHASE INHIBITORS<O></O>
By<O></O>
B. A. Miksic and R. H. Miller<O></O>
The Cortec Corporation<O></O>
St. Paul, Minnesota<O></O>
Published: September 1980,<O></O>
5th European Symposium on Corrosion Inhibitors,<O></O>
European Federation of Corrosion, Italy<O></O>
SUMMARY<O></O>
The inhibition of atmospheric corrosion of both ferrous and nonferrous metals<O></O>
demands the application of chemical compounds which posses high passivating properties,<O></O>
strong tendencies toward surface adsorption, and the ability to form a comparatively<O></O>
strong and stable bond with metal surface. The delicate and yet complex nature of<O></O>
atmospheric corrosion processes occurring under thin films of electrolyte preordains the<O></O>
transport mechanism of corrosion inhibitor which- in order to become effective, must<O></O>
diffuse through the electrolyte film and cover the substantial portion of the surface. The<O></O>
precise parameters of the corrosion inhibiting mechanism are still unknown. It is believed<O></O>
that certain physical and chemical properties of the benevolent molecules are critically<O></O>
important, e.g., vapor pressure saturation levels, molecular structural characteristics,<O></O>
availability of reactive groups for surface physical or chemical binding, the polarity, the<O></O>
contamination, the resultant conductivity of the electrolyte, etc. There is a considerable<O></O>
controversy over the importance of, and the relationship between the saturated vapor<O></O>
pressure and its influence on the effectiveness of the specific VCI compound. Various<O></O>
investigations have either (1) emphasized the significance of minimum acceptable values of<O></O>
vapor pressure to achieve vaporization or (2) stressed the importance of electrochemical<O></O>
factors in altering the kinetics of partial corrosion processes. The many critical<O></O>
requirements made on an inhibitor of atmospheric corrosion have severely limited the<O></O>
number of compounds acceptable to solve the practical corrosion problems existing in the<O></O>
industry.<O></O>
ctp13.doc (ck) 6/30/98 2 of 20<O></O>
INTRODUCTION<O></O>
It is sincerely believed that it is indeed the time to bring the spirit of innovation in<O></O>
to the field of atmospheric corrosion inhibitors.<O></O>
What happened in 1973, 1974 and as recently as a few months ago, was an early<O></O>
sign of complex problems that will employ much skilled human resource to bring an<O></O>
acceptable and economical solution. Since the subject of potential energy and material<O></O>
resource shortages is well known to you, I will stay with it only long enough to bring a<O></O>
point across, my belief that those energy and material shortages do represent a serious<O></O>
challenge, and perhaps, an unusual opportunity for future innovative ideas and concepts.<O></O>
Due to their unique protective mechanism, I trust inhibitors of atmospheric<O></O>
corrosion do fall in the category of innovative concepts, concepts which may help preserve<O></O>
natural resources, so important to our modern society.<O></O>
However, an equally serious potential shortage is much less tangible. In essence it<O></O>
is a shortage of one of the most essential ingredients of technical innovation:<O></O>
The Results of Basic Scientific Research<O></O>
Support of basic research in the area of chemical corrosion inhibitors by the<O></O>
National Science Foundation, by professional societies, by research institutes, and by trade<O></O>
association has been minimal. Support of basic research in the area of volatile corrosion<O></O>
inhibitors, to the best of my knowledge has been negligible in the past twenty five years.<O></O>
With increasing barriers to innovation there is a need to initiate and to continue the<O></O>
innovation process by stimulating the basic research.<O></O>
Volatile Corrosion Inhibitors represent the most economical and yet extremely<O></O>
powerful tool in combating the atmospheric corrosion damage to metals and alloys. It is<O></O>
estimated that in the U.S. alone direct cost of atmospheric corrosion to the industry,<O></O>
government and consumers amounts to about $20 billion annually. Indirect damages are<O></O>
almost impossible to express in terms of dollar value since they consist of such important<O></O>
resources as energy needed to manufacture replacements for corroded objects, humans<O></O>
killed or disabled as a result of failures of corroded structures, artifacts lost as a result of<O></O>
corrosive attack, etc.<O></O>
The concept of volatile corrosion inhibition utilizes conditioning of the<O></O>
environment with trace amounts of inhibitive material to achieve the protective effect.<O></O>
Classical methods involve either changing the composition of an alloy or covering the<O></O>
metal with a protective coating. In some instances, like, scientific instruments, electrical<O></O>
and electronic equipment, etc. it is even impossible to adopt classical methods of<O></O>
prevention and that is the area where the usefulness of VCI’s is probably most obvious.<O></O>
ctp13.doc (ck) 6/30/98 3 of 20<O></O>
However, due to scarce information and general disinterest of the public for new<O></O>
and improved methods of protection, very little has been done in the past thirty years to<O></O>
develop new VCIs. Two compounds that have been developed in the late forties,<O></O>
dicyclohexylamine nitrite and diisopropylamine nitrite, have been accepted as standards,<O></O>
and virtually no effort has been made to upgrade or develop new compounds with<O></O>
improved performances.<O></O>
The National Association of Corrosion Engineers has only recently recognized the<O></O>
importance of these compounds by sponsoring an International Symposium and a task<O></O>
group devoted exclusively to the VCIs. The purpose was to initiate new researches, to<O></O>
collect and develop the information on VCI technology and to make the information<O></O>
available to the industry and other interested parties.<O></O>
THE NOMENCLATURE<O></O>
According to Fischer, (1) corrosion inhibitors can be divided in two categories<O></O>
(Table 1).<O></O>
1. Interface Inhibitors<O></O>
Interface inhibitors decrease the velocity of<O></O>
physical, electro-chemical and/or chemical processes<O></O>
of electrode reactions taking place immediately at the<O></O>
metal/electrolyte interface.<O></O>
2. Electrolyte - Layer Inhibitors<O></O>
Electrolyte - Layer inhibitors may decrease the velocity<O></O>
of physical and chemical processes of the electrode reactions<O></O>
taking place in the electrolyte layer which adheres to the interface.<O></O>
This layer may be a diffusion part of the double layer,<O></O>
the Nernst diffusion layer or Prandtl’s flow boundary layer.<O></O>
Electrolyte-layer inhibition is caused by substances dispersed<O></O>
or dissolved in the mentioned electrolythe-layer.<O></O>
Further, Fischer classifies inhibitors into Primary Inhibitors or Secondary Inhibitors<O></O>
depending upon the origin of protective species:<O></O>
- Primary Inhibitors are substances that are a priori present in the<O></O>
bulk of the electrolyte layer without chemical change of their<O></O>
composition.<O></O>
- Secondary Inhibition is caused by the substances which are not<O></O>
a priori present in the bulk of the electrolyte. They must be<O></O>
generated at the interface or in the electrolyte layer by a chemical<O></O>
or electrochemical process.<O></O>
ctp13.doc (ck) 6/30/98 4 of 20<O></O>
In order to contribute to the problem of classification and proper identification of<O></O>
VCI compounds the following definition is proposed:<O></O>
Volatile Corrosion Inhibitors are secondary electrolyte layer inhibitors that possess<O></O>
appreciable saturated vapor pressure under atmospheric conditions, thus allowing vapor<O></O>
phase transport of the inhibitive substance.<O></O>
By definition, only compounds that are volatile under atmospheric conditions and<O></O>
can act as electrolyte layer inhibitors by electro-chemically changing the kinetics of<O></O>
electrode reactions should be classified as VCI’s. Neutralizing amines, for instance, do<O></O>
have an appreciable vapor pressure, and are effective inhibitors for ferrous metals, but<O></O>
their mechanism is based on adjusting the pH value of the electrolyte thus creating<O></O>
conditions inhospitable for formation of rust; hence, they should not be necessarily<O></O>
classified as volatile corrosion inhibitors.<O></O>
By definition a VCI compound in addition to being volatile is required to promote<O></O>
the electrochemical effects such as change of the yo, - potential in the diffuse part of the<O></O>
double layer which controls the migration of components of the electrode reactions.<O></O>
THE MECHANISM<O></O>
It was pointed out by Balezin, (2) that every inhibitor of corrosion, including<O></O>
volatile ones, should:<O></O>
a. be capable of establishing a stable bond with the metal surface in<O></O>
a given environment of a certain range of acidity and pressure.<O></O>
b. create a layer impenetrable to the corroding ions.<O></O>
The Mechanism of inhibition is shown in Fig. 1.<O></O>
The functional group R1 linked to the nucleous Ro of the inhibitor molecule is<O></O>
responsible for adsorption in a given environment. The functional group R2 also linked to<O></O>
the nucleus Ro is responsible for the thickness and the impenetrable nature of the film<O></O>
formed. In designing the inhibiting compound for particular environment, it is first<O></O>
necessary to vary the functional group R1 until a substance capable of being firmly<O></O>
adsorbed on the metal surface is obtained. Having thus determined R1 we vary the<O></O>
functional group R2 until satisfactory resistance to penetration of aggressive ions is<O></O>
achieved. The use of the above principles of selection enables one to develop corrosion<O></O>
inhibitors effective over a variety of metals and environments.<O></O>
In designing a volatile corrosion inhibiting compound, however, we have to assure<O></O>
ourselves that the compound will have an appreciable vapor pressure, as well as the<O></O>
capability of forming a stable bond with the metal surface. It is well known that the vapor<O></O>
pressure of a chemical compound largely depends upon the structure of the crystal lattice<O></O>
and the character of the atomic bond in the molecule. Therefore, if an inorganic<O></O>
ctp13.doc (ck) 6/30/98 5 of 20<O></O>
compound contains a desired protective group (anion), an organic radical can be<O></O>
substituted for the inorganic cation, so that an organic salt is obtained which will possess<O></O>
the two desired properties:<O></O>
- a protective group<O></O>
- a volatility<O></O>
However, it is not always possible to obtain successfully both of these properties in<O></O>
one compound. The protective anion may be too heavy to vaporize into the air. This, in<O></O>
all possibility is the reason why so few volatile inhibitors have been synthesized with<O></O>
chromate as the anion. Sometimes the vapor pressure of the synthesized compound<O></O>
becomes so high that the steps must be taken to reduce it.<O></O>
High vapor pressure compounds reach the protective vapor concentration rapidly,<O></O>
but in the case of enclosures that are not airtight, the consumption of inhibitor is quick and<O></O>
resulting protective periods are short. On the other hand, low vapor pressure inhibitor is<O></O>
not used up so quickly and can assure more durable protection, but more time is required<O></O>
to achieve a protective vapor concentration. Furthermore, there is a possibility of<O></O>
Continued to next postingLast edited by Rich Moran; 04-19-2010, 01:52 AM.Comment
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Doncha love incomplete sentences, CONCENTRATE NOW!!!
corrosion during initial period of saturation, and if the space is not hermetically sealed, a<O></O>
protective inhibitor concentration may never be obtained (Fig. 2).<O></O>
Therefore, the chemical compound used as a volatile inhibitor must not have too<O></O>
high or too low vapor pressure, but some optimum vapor pressure (Fig. 3).<O></O>
To determine the saturated vapor pressure of volatile inhibitors and their<O></O>
temperature dependence, two experimental methods have been employed: Rosenfeld<O></O>
Martin Knutsen effusion method (3) and (4) dynamic flow method. Analysis of data found<O></O>
in the literature points at certain inconsistency in vapor pressure values published by<O></O>
different authors. It is believed that the reproducibility of data depends upon experimental<O></O>
parameters that are inherent properties of the test method employed. It was showed (5)<O></O>
that measured vaporization rates in vacuo and in the atmosphere are not equal and that<O></O>
differences for the same compound could be relatively large. This partially explains<O></O>
difficulties encountered in correlating vapor pressure data obtained with different<O></O>
experimental techniques. According to Rosenfeld few effects are possible:<O></O>
1. the change in the total pressure modifies Gibbs’ free energy for the<O></O>
components of the condensed phase.<O></O>
2. an extraneous gas slows down the vaporization of the condensed<O></O>
phase components (kinetic effect).<O></O>
3. part of the vapor, for instance the water vapor, dissolves in the<O></O>
condensed phase and modifies Gibb’s free energy of the latter.<O></O>
ctp13.doc (ck) 6/30/98 6 of 20<O></O>
All of the above mentioned factors can show different effects, even in sign, on the<O></O>
vaporization rate. However, a researcher should be aware of the fact that vapor pressure<O></O>
values depend on the total pressure and, as should be expected, on the composition of the<O></O>
surrounding atmosphere. The vapor pressure dependence of volatile inhibitors upon<O></O>
temperature is given in Fig. 2.<O></O>
Considering that the vapor pressure of VCIs satisfactorily conforms to straight<O></O>
lines (in the - LgP vs 1/T coordinate system), the latent heat of sublimation can be<O></O>
calculated by Clapeyron - Claussius equation (6).<O></O>
LgP = A/T + B<O></O>
The comparison between the vapor pressure of a compound and its molecular heat<O></O>
of sublimation shows a marked decrease in vapor pressure values with increase in a heat<O></O>
sublimation. This is a reason to believe that decrease in vapor pressure may be accounted<O></O>
for by steric intermolecular interactions between functional groups and by increase in<O></O>
molecular weight of the compound (Table II).<O></O>
It is significant that all of the most effective volatile corrosion inhibitors are the<O></O>
products of reaction of weak volatile base with a weak volatile acid. Such substances,<O></O>
although ionized in aqueous solution undergo a substantial hydrolysis, the extent of which<O></O>
is almost independent of concentration. In the case of the amine nitrites and amine<O></O>
carboxylates the net result of those reactions may be formulated as:<O></O>
R2NH2<O></O>
+ + NO2<O></O>
- R2NH +HNO2<O></O>
R2NH2<O></O>
+ +R1 COO- R2NH + R1COOH<O></O>
In further support of the mechanism of vapor-phase transport postulated it can be<O></O>
noted that amine salts such as dicyclohexylammonium nitrate or diisobutylammonium<O></O>
sulfate, which are not extensively dissociated by water, do not give significant vapor phase<O></O>
inhibition. The same is true for slightly hydrolized alkali metal salts such as sodium nitrite<O></O>
or sodium benzoate, although the latter are excellent rust inhibitors when their solutions<O></O>
are in direct contact with metal surface.<O></O>
A series of interesting experiments have been run by Zisman and Baker (7) at the<O></O>
Naval Research Laboratories to determine the relationship between pH of solution and the<O></O>
rate of emission of hydrolytic or thermal dissociation products. It was shown that<O></O>
appreciable volatilization of both components of an amine carboxylate or an amine nitrite<O></O>
will probably be only in the approximate pH range of 5.5 to 8.5. On the acid side of the<O></O>
neutral point the useful inhibiting range is limited by the fact that when the volatile acid<O></O>
constituent is present in the vapor in excess it will dissolve in the condensate on the metal<O></O>
surface to give it an even lower pH, which in the case of nitrous acid or short chain<O></O>
organic acids, may actually accelerate rusting.<O></O>
ctp13.doc (ck) 6/30/98 7 of 20<O></O>
The results of indicator experiments with various solutions of dicyclohexylamine<O></O>
nitrite and of diisopropylamine benzoate are summarized in Table II which shows that the<O></O>
pH produced by such inhibitors in the condensate forming on exposed steel surfaces<O></O>
depends strongly on the saturated inhibitor solution from which the protective vapors<O></O>
originate (Table III).<O></O>
The pH of the inhibitor preparation, therefore, affects not only the initial volatilities<O></O>
of the inhibitor, but also the effectiveness of its operation after it reaches the metal surface.<O></O>
At a pH above 8.5 an acid is present almost exclusively as nonvolatile anion and any<O></O>
inhibition noted from an amine carboxylate in this range is attributable to the volatile<O></O>
amine, which has definite, although inadequate, corrosion-inhibiting properties in its own<O></O>
rights.<O></O>
The secondary alkylamine nitrites react in the presence of small traces of inorganic<O></O>
acid to give nitrosoamine, which is not an efficient corrosion inhibitor. This limits their<O></O>
use to acid free systems or indicates the use of an alkaline buffer. On the other hand, in<O></O>
the presence of excess alkali the free amine and an alkali nitrite are formed. Thus, for<O></O>
satisfactory operation an effective buffer must be used to maintain the pH at a level<O></O>
definitely on the alkaline side.<O></O>
NATURE OF ADSORBED FILMS<O></O>
Even more important for the efficiency of volatile corrosion inhibitors than the pH<O></O>
effects just discussed, is the nature of adsorbed film formed at the steel-water interface.<O></O>
Metal surfaces exposed to vapors from the VCI’s in closed containers give evidence of<O></O>
having been covered by a hydrophobic adsorbed layer. The contact angle of distilled<O></O>
water on such surfaces, increased with the time of exposure as shown in Fig. 4 (8).<O></O>
The change in the contact angle by the interaction between the inhibitor and the<O></O>
metal surface has been measured after removing excess inhibitor with the solvent. It has<O></O>
been established that after 7 days exposure the contact angle increased from 170 - 200%<O></O>
of original value. Further increase is only moderate and levels off at about 275% for<O></O>
steel, 137% for copper and magnesium and 120% for zinc after 3 months exposure.<O></O>
The greatly increased protection against rusting that results when both acid and<O></O>
amine are present is noteworthy and deserves further study. The data available does not<O></O>
make clear whether the gain is a result of synergism between adsorbed acid and amine to<O></O>
give a more firmly held momolayer that could be formed by either one alone. It is<O></O>
important that the mixed film when adsorbed at the water-air interface is highly<O></O>
condensed. It is also conceivable that the mixed film serves as a buffer to hold the pH at<O></O>
the interface in the optimum range for corrosion resistance. Another possibility is that<O></O>
amine and acid contribute to the corrosion inhibition by different but additive mechanisms.<O></O>
Experimental studies on the adsorption of volatile inhibitors from the gas phase<O></O>
confirm the assumption that VCI’s react with the metal surface thus providing corrosion<O></O>
ctp13.doc (ck) 6/30/98 8 of 20<O></O>
protection. When a steel electrode is exposed to vapors of a volatile inhibitor, the steadystate<O></O>
electrode potential shifts considerable into the region of positive values (Fig. 5).<O></O>
The higher the vapor pressure, the stronger is the shift of the electrode potential in<O></O>
positive direction. Inhibitor adsorption is not a momentary process and requires much<O></O>
time for completion. This indicates that the adsorption is chemical and not physical in<O></O>
nature, resulting in a chemisorbed layer on the metal surface. However, these<O></O>
chemisorbed layers cannot be considered as protective phase films since the bond between<O></O>
the inhibitor and the metal surface is not strong enough to prevent the adsorbed inhibitor<O></O>
from leaving the metal surface when the metal is removed from the inhibitor saturated<O></O>
atmosphere. It is obvious that if stable chemical compounds were formed to produce a<O></O>
phase film on the metal surface, the adsorbed inhibitor could not leave the metal surface as<O></O>
freely as it does.<O></O>
Therefore, it can be concluded that to insure continuous reliable protection a<O></O>
steady supply of inhibitor should be maintained from the gas phase to the metal surface.<O></O>
The nature of adsorbed films has been studied with the use of autoradiography (9). The<O></O>
results were indicative of the fact that separation takes place in the atmosphere, and the<O></O>
inhibitor’s molecule is separated when adsorbed on the metal surface. The mixed nature<O></O>
of adsorbed film has been thus experimentally confirmed, showing the existence of<O></O>
inhibitor’s molecule in dissociated (separate) form, an anodic and cathodic inhibitor<O></O>
respectively, which explains the synergism that has been postulated in studies of Zisman<O></O>
and Baker over thirty years ago.<O></O>
The attempts to adopt flame ionization detector with sensitivity of 10-7 - 10-9 g/m2<O></O>
to study the process of adsorption of volatile corrosion inhibitors have proven reasonably<O></O>
successful in having sufficient sensitivity to detect adsorption of compounds with vapor<O></O>
pressure of 10-7mm Hg and lower (10). It was found that the amount of adsorbed<O></O>
inhibitor increases with temperature which is indicative of above mentioned activated<O></O>
character of adsorption. Knowing the pressure of saturated inhibitor vapor, and the flow<O></O>
rate of the carrier gas, it is possible to calculate the amount of inhibitor molecules<O></O>
adsorbed on the metal. It proved much lower than the amount necessary to form<O></O>
monomolecular layer. A negligible surface coverage on highly polished metal surfaces is<O></O>
attributed to equilbrated adsorption - desorption process. The parameters of the process<O></O>
change, however, with the change in surface roughness; it was found that corrosion<O></O>
growth on the surface, for instance, will promote adsorption sites for volatile inhibitor by<O></O>
probably increasing the active surface area. It is likely that inhibitors saturate the free<O></O>
valencies of surface metal ions, changing the chemical properties of the surface. These<O></O>
changes, however, take place on activated sites only, and not on inactive ones, where the<O></O>
inhibitor desorbs at the same rate as it is being adsorbed.<O></O>
OVERVIEW OF PERFORMANCE TESTS<O></O>
ctp13.doc (ck) 6/30/98 9 of 20<O></O>
Attempts to develop a reliable laboratory experiment that would provide usable<O></O>
information on behavior of volatile corrosion inhibitors have been only partially successful.<O></O>
It is extremely difficult to reproduce atmospheric conditions encountered during field<O></O>
application and to design the test that would give meaningful results in a relatively short<O></O>
period of time. Acceleration of test conditions with artificially increased concentrations of<O></O>
sulfur dioxide, hydrogen sulfide or sodium chloride are representative of specific<O></O>
atmospheres, industrial, oil-field and marine for instance, but information obtained in those<O></O>
tests should not be directly correlated to actual field performance.<O></O>
One of the first experimental set-ups used to study VCIs was developed by Vernon and<O></O>
Stroud (1).<O></O>
Solution on the bottom of the test chamber contains dissolved corrosive gases, i.e.,<O></O>
sulfur dioxide, at desired concentrations, which causes the acceleration of corrosion<O></O>
experiment.<O></O>
CONTINUED WITH COMPLETE SENTENCES TO THE NEXT POSTComment
-
By using the above described test method amine carbonates have been shown to<O></O>
afford corrosion protection to steel, and a variety of non-ferrous metals in moist<O></O>
atmospheres polluted with sulfur dioxide. The same inhibitors, however, initiated<O></O>
corrosion of copper and copper base alloys which is probably due to corrosive action of<O></O>
carbonic acid formed by combining carbon dioxide and water in condensed moisture layer<O></O>
on the metal surface. Carbon dioxide and volatile amine are products of dissociation of<O></O>
amine carbonate inhibitor.<O></O>
As shown in (11). amine carbonates are effective inhibitors of steel corrosion in<O></O>
atmospheres containing rather high concentrations of sulfur dioxide.<O></O>
Considerable effort has been applied by Wachter and Stillman (12) to development<O></O>
of a rapid laboratory test that would give a more reliable indication of the efficacy of<O></O>
volatile corrosion inhibitors for protective packing than is offered by humidity cabinet<O></O>
tests. The dynamic test accordingly developed is made by passing clean air at 105oF at a<O></O>
rate of 120 cc per minute for the test period of 44 hours through the apparatus illustrated<O></O>
schematically in (12). It is interesting that several amines, which passed some static tests<O></O>
perfectly failed in the dynamic test.<O></O>
By using this method it was possible to study the kinetics of vaporization of<O></O>
volatile corrosion inhibitors. The rate at which vaporization of dicyclohexylamine nitrite<O></O>
occurs at room temperature is shown in Fig. (10) from experiments in which sheets of<O></O>
Dichan impregnated paper were suspended in an air stream flowing at constant velocity of<O></O>
100 ft. per minute over both sides of each sheet.<O></O>
It was demonstrated that a sheet containing 1 gram of Dichan per square foot<O></O>
would be deleted in about three weeks under those test conditions (12). Accelerated test<O></O>
method has been developed by Levin to study the effectiveness of VCIs in simulated<O></O>
tropical climates (8).<O></O>
ctp13.doc (ck) 6/30/98 10 of 20<O></O>
The results of those tests are indicative of the influence of chain length of the<O></O>
aliphatic acid used in preparation of the inhibitor on the effectiveness of protection. Fig.<O></O>
(11).<O></O>
The efficiency of volatile corrosion inhibitor with increase in the chain length of<O></O>
aliphatic acid can probably be explained by a stronger hydrophobisation effect which is<O></O>
due to increased contact angle, as discussed above.<O></O>
The need for a suitable electrochemical method for studying volatile corrosion<O></O>
inhibitors has been pronounced ever since VCIs were discovered. The attempts to<O></O>
correlate the electrochemical measurements in a volume of electrolyte with actual<O></O>
atmospheric conditions happening under thin films of electrolyte, have been unsuccessful<O></O>
due to drastic changes in electrochemical behavior of metals under those two conditions.<O></O>
Rosenfeld and his co-workers have succeeded to develop an apparatus suitable for<O></O>
electrochemical measurements of atmospheric corrosion of metals under thin films of<O></O>
electrolyte (13). That apparatus was later adopted for the study of volatile corrosion<O></O>
inhibitors when the inhibitors saturated those films with condensation of their vapors.<O></O>
The potential shift to the region of positive values led Rosenfeld to believe that the<O></O>
volatile inhibitors slow down the rate of the anode reaction.<O></O>
Indeed, kinetic studies of the anode process in the atmosphere of amines and their<O></O>
salts have shown that anode reaction sharply diminishes, the effect being mostly<O></O>
pronounced in the presence of free amines. The effect of amine salts also is to slow down<O></O>
the reaction of ionization of metals, but however, the effect is considerably less<O></O>
pronounced.<O></O>
It has been demonstrated that, hydroxyl ions and anions of acids formed as a result<O></O>
of dissociation and hydrolysis of amines and their salts determine the mode of inhibition of<O></O>
the corrosion process. Protection given by those compounds is due to the presence in<O></O>
their structure of complex organic cations which contain pentovalent nitrogen in the ring.<O></O>
According to literature sources, nitrogen of the amine group is capable of entering into a<O></O>
coordinate bond with metals thus enhancing the adsorption process. Adsorption of<O></O>
cations increases the overpotential of metal ionization and slows down the corrosion. In<O></O>
the case of amine salts the protective role is also attributed to the acid portion of the<O></O>
molecule. It is known that nitrites and benzoates are capable of inhibiting the anode<O></O>
reaction. Certain compounds, namely salts of amines and substituted benzoic acids, and<O></O>
esters of chromic acid are capable of slowing down the kinetics of cathode reaction in<O></O>
addition to being effective anodic corrosion inhibitors.<O></O>
Traditional VCI’s mainly compounds containing nitrite group, possess one<O></O>
essential shortcoming; they protect ferrous metals and attack non-ferrous metals, like zinc<O></O>
and its alloys. Electric and electrolic equipment, instruments, engines, etc., are only rarely<O></O>
built of exclusively ferrous metals and this severely limits application of nitrite VCIs. The<O></O>
ctp13.doc (ck) 6/30/98 11 of 20<O></O>
recent development in the field of VCIs represents the synthesis of compounds which can<O></O>
act at the same time as anodic and cathodic inhibitors and have satisfactory volatilization<O></O>
rates. These inhibitors are (usually) called mixed inhibitors and their main advantage over<O></O>
traditional VCI’s is the fact that they do not adversely affect certain non-ferrous metals,<O></O>
but, in fact, they do protect most of the common engineering metals and alloys (Fig. 7).<O></O>
The inhibition of cathodic process is achieved by incorporation of one or more<O></O>
oxidizing anions in an organic molecule of a VCI compound. In contrast to inorganic<O></O>
anions which reduce with a great difficulty on an iron cathode in neutral electrolyte, the<O></O>
same anions introduced into the benzene ring, for instance, will show enhanced reduction<O></O>
process of the neutral group. Further acceleration of the cathodic process rate can be<O></O>
accomplished by the introduction of an electrophilic substitute which can reduce the<O></O>
nitrogen electron density and thereby accelerate the reduction process. Carboxyl and<O></O>
second nitrite groups are considered to be very effective electrophilic substituents, and<O></O>
with them a compound can be obtained that rapidly reduces on an iron cathode. However,<O></O>
inhibitors designed in this manner show weakness in environments containing high<O></O>
concentrations of aggressive ions, i.e., chlordie ions, where the current density required<O></O>
for acceleration of cathodic reaction is commensurate with passivation current.<O></O>
We have investigated the influence of volatile corrosion inhibitor on hydrogen<O></O>
embrittlement of high strength steel (15). It was postulated that those inhibitors could<O></O>
promote hydrogen embrittlement resistance in neutral or near neutral environment. For<O></O>
that study a test method was developed by using fatigue precracked compact tension<O></O>
specimens. A layer of electrolyte of controlled thickness of 160 M was created on the<O></O>
crack; the electrolyte was distilled water containing 1.0% concentration of volatile<O></O>
corrosion inhibitor.<O></O>
It was felt that these test conditions correlate fairly well with conditions found<O></O>
during exposures to humid atmospheres, that enhance hydrogen embrittlement of high<O></O>
strength steels. The concentration on inhibitor in the electrolyte layer is representative of<O></O>
concentrations obtained by sublimation and condensation of inhibitor vapors in electrolyte<O></O>
films on metal surfaces.<O></O>
Plotting crack velocity versus stress intensity (Table IV) shows definite<O></O>
improvement in retarding crack growth from hydrogen chemisorption when inhibited<O></O>
distilled water was used, as compared to uninhibited water (Table III).<O></O>
Of three inhibited environments, amine carbonate inhibitor showed the least<O></O>
improvement but still was significantly better than the control (uninhibited) environment.<O></O>
Organic nitrite salt inhibitor was by far the most effective, not only having the highest<O></O>
threshold stress intensity but also a crack growth rate that increased very slowly until<O></O>
applied stress intensity approached the catastrophic stress intensity at which point it<O></O>
increased very rapidly to failure.<O></O>
ctp13.doc (ck) 6/30/98 12 of 20<O></O>
This presentation is intended to be an overview and a summary of information on<O></O>
atmospheric corrosion inhibitors.<O></O>
In conclusion, we would like to express our belief that for people involved in the<O></O>
work with chemical corrosion inhibitors, VCIs should represent a serious challenge since<O></O>
they encounter all aspects of inhibition and adsorption phenomena plus an unique vapor<O></O>
phase transport mechanism. We feel that the key to future success of VCI technology lies:<O></O>
1. In initiating basic research studies, and;<O></O>
2. In developing information on their effect on the environment.<O></O>
Potential users like steel and automotive manufacturers, oil refining and<O></O>
transportation that suffer enormous damages due to atmospheric corrosion are not in a<O></O>
position to use VCIs on a larger scale unless clearance from governmental agencies<O></O>
concerned with toxicity and pollution becomes available.<O></O>
If this talk in any way will solicit interest of you corrosion people present in this<O></O>
room, I will feel as though I made a major contribution. Benefits that potentially could be<O></O>
derived from new and improved methods of corrosion control, will, in a long run help<O></O>
preserve important raw materials and energy resources.<O></O>
ctp13.doc (ck) 6/30/98 13 of 20<O></O>
REFERENCES<O></O>
(1) Fischer, H., Comptes Rendus de 2 eme Europeen Symp. sur les Inhibiteurs de<O></O>
Corrosion, Ferrara, 1966.<O></O>
(2) Balezin, S.A., Comptes Rendus de 2 eme Europeen Symp. Sur les Inhibiteurs de<O></O>
Corrosion, p. 277 (1966).<O></O>
(3) Martin, P., Jr., J. Chem, Engr. Data, Vol. 10, No. 3 (1965).<O></O>
(4) Persiantseva, V.P., etal, Zaschita Metallow 7 (4), P. 392, (1971).<O></O>
(5) Rosenfeld, I.L., etal, Zaschita Metallow 10 (4), P. 339, (1974).<O></O>
(6) Baker, H.R., Industrial and Engineering Chemistry, Vol. 46, No. 12 (1965).<O></O>
(7) Levin, S.Z. etal, Comptes Rendus de 2 eme Sypm. Europeen sur les Inhibiteurs<O></O>
de Corrosion P. 765.<O></O>
(8) Henriksen, J.F., Corrosion ‘76 Annual N.A.C.E. Meeting, Houston, (1976).<O></O>
(9) Rosenfeld, I.L., Corrosion ‘76 N.A.C.E. Annual Meeting, Houston, Texas,<O></O>
(1976).<O></O>
(10) Stroud, E.C., Vernon, W. H. J., J. Appl. Chem., 2.4. (1952).<O></O>
(11) Wachter, A., etal, Corrosion, 7, 284, (1951).<O></O>
(12) Rosenfeld, I.L., etal 4th Int. Congr. Mat. Corr., Amsterdam, 606-9, (1969)<O></O>
N.A.C.E.<O></O>
(13) Miksic, B.A., Chemical Engineering, September 1977.<O></O>
(14) Gerberich, W.W., Miksic, B. A., Private Communications, August 1975.<O></O>
ctp13.doc (ck) 6/30/98 14 of 20<O></O>
Table II - Saturated vapor pressures of common VCIs<O></O>
Substance Temperature<O></O>
oC<O></O>
Vapor<O></O>
Pressure<O></O>
Melting Point<O></O>
oC<O></O>
Morpholine 20 8.0<O></O>
Benzylamine 29 1.0<O></O>
Cyclohexylamine Carbonate 25.3 .397<O></O>
Diisopropylamine Nitrite 21 4.84 x 10-3 139<O></O>
Morpholine Nitrite 21 3x10-3<O></O>
Dicyclohexylamine Nitrite 21 1.3x10-4 179<O></O>
Cyclohexylamine Benzoate 21 8x10-5<O></O>
Dicyclohexylamine Caprylate 21 5.5x10-4<O></O>
Guanadine Chromate 21 1x10-5<O></O>
Nexamethyleneimine Benzoate 41 8x10-4 64<O></O>
Nexamethyleneimine Nitrobenzoate 41 1x10-6 136<O></O>
Dicyclohemylamine Benzoate 41 1.2x10-6 201<O></O>
Log T= -A/T - B<O></O>
Table III - pH of water in equilibrium with vapor above aqueous<O></O>
solutions of volatile corrosion inhibitors as compared<O></O>
with pH of later phase<O></O>
Inhibitor Concentration Solution Condensate<O></O>
Wt% pH pH<O></O>
Diisopropylamine benzoate 5.0 7.0 7.0<O></O>
Diisopropylamine benzoate +<O></O>
excess bezoic acid 6.0 5.0 4.0<O></O>
Diisopropylamine benzoate +<O></O>
excess diisopropylamine 6.0 3.0 10.00<O></O>
Dicyclohexylamine nitrite 7.00 10.0 10.0<O></O>
Dicyclohexylamine nitrite + 5.0 7.2 7.0 +<O></O>
excess NaNO2 + HCI 6.0 4.5 3.0÷4.0<O></O>
Dicyclohexylamine nitrite + 6.0 8.0 9.0<O></O>
excess dicyclohexylamine 7.0 8.0+ 9.0<O></O>
ctp13.doc (ck) 6/30/98 15 of 20<O></O>
TABLE IV - Effectiveness of Different Organic Corrosion Inhibitors<O></O>
in Preventing Hydrogen Embrittlement of 300M Steel.<O></O>
Distilled Water<O></O>
Average velocity (in/sec) Average Applied Stress Intensity<O></O>
(pat-in).<O></O>
7.38 x 10 -6 22500<O></O>
7.02 x 10 -6 29000<O></O>
9.50 x 10 -6 34700<O></O>
1.64 x 10 -5 44600<O></O>
1.90 x 10 -5 57300<O></O>
2.61 x 10 73800<O></O>
Threshold stress intensity 6404<O></O>
Inhibitor Code C-1<O></O>
4.17 x 10 -7 29000<O></O>
1.96 x 10 -6 35900<O></O>
9.15 x 10 -6 42500<O></O>
9.56 x 10 -6 52400<O></O>
1.79 x 10 -5 64900<O></O>
Threshold stress intensity 29700<O></O>
Inhibitor Code C-8<O></O>
0.0 32650<O></O>
0.0 38500<O></O>
6.37 x 10 -6 45950<O></O>
9.81 x 10 -6 56300<O></O>
Threshold stress intensity 37600<O></O>
(continued)<O></O>
Table IV - (continued)<O></O>
ctp13.doc (ck) 6/30/98 16 of 20<O></O>
Distilled Water<O></O>
Inhibitor Code A-4<O></O>
Average Velocity (in/sec) Average Applied Stress Intensity<O></O>
(psi-in).<O></O>
0.0 32600<O></O>
0.0 70800<O></O>
8.56 x 10 -7 49300<O></O>
0.0 55750<O></O>
7.85 x 10 -6 55800<O></O>
3.04 x 10 -6 62600<O></O>
8.33 x 10 -5 66700<O></O>
1.74 x 10 -5 69000<O></O>
Threshold stress intensity 40800<O></O>
ctp13.doc (ck) 6/30/98 17 of 20<O></O>
ctp13.doc (ck) 6/30/98 18 of 20<O></O>
ctp13.doc (ck) 6/30/98 19 of 20<O></O>
ctp13.doc (ck) 6/30/98 20 of 20<O></O>
Figure 7<O></O>
Typical Corrosion Rates for Non-ferrous Metals<O></O>
Exposed to Atmosphere Containing VCI<O></O>
0<O></O>
2<O></O>
4<O></O>
6<O></O>
8<O></O>
10<O></O>
12<O></O>
14<O></O>
Cu Cd Zn Mg Al<O></O>
Control<O></O>
Anodic Inhibitor<O></O>
Cathodic Inhibitor<O></O>
BothComment
-
Since the paper was written eons ago, leaps and bounds in advances have been made on tweaking the amine carboxylate to a clean & easily applied inhbitors for definite use of corrosion inhibiting.
We have a article & report from April 2004 Gun magazine regarding CORTEC produced Bullfrog Gun Preservation products. Limitations of attachment size is coming into play here.
If you go here:
http://www.bull-frog.com/publication...es/gunsMag.pdf
and here:
http://www.bull-frog.com/publication...y_seashore.php
So with this I wish that this will finally bury "here say" about these systems as the system is proven to work.
Anyone would like more information on wheeled and tracked gear, artillery pieces or whatever your need is when time permits I will be more than happy to reply.Comment
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Well, it has been almost a month since this started and with the last bout & exchange, there has been zero in reasoning of how to work to slow corrosion/oxidation on bullion once it starts.
I think a month is more than what is required to do some type of research to post a meaningful dialouge of give and take and this has not occured. There is a ton of information on the web and it is available under the Freedom of Information Act.
As advised, people who sit on their hands and watch an artifcat being consumed by a natural course of corrosion will be at a total loss with zero activity without CPAC (corrosion prevention and control) always make me puzzled in what the reasoning is for the inactivity.
Worse, someone charged with the responsibility to maintain for age artifacts that they are consigned to do so & allow corrosion issues to continue due to their inactivity/unwillingness to explore new systems with an open mind
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This situation and end result happens far too often and can be a direct cause of certain artifacts becoming that much more rare due to the fact of the loss of artifacts to corrosion.
When one considers that fact that corrosion seems to be something one can surrender to, the fact is one should not by saying "oh well, there is nothing you can do" when in fact there is something that can be done and done intellegently, dillegently to a timed system that also incorporates corrosion assessing with a follow up plan of attack should a situation become worse.
If the corrosion situation remains stable, that is excellent, job well done.
If the corrosion issue becomes one of more activity, understanding last application date, time to performance and renewed activity places emphasis on scheduled retreatments with inhbitors to again, bring the cororsion issue under control.
Lastly, for an FYI on this, I've served the DoD community in Hawaii since 1996, have performed with a team over 40,000 applications of inhibitor spray to the tactical fleet as well as have serviced both Army museums on Oahu. In addition, I am a memeber of Hawaii Historic Arms Society and many of my fellow members have enjoyed being able to save their artifacts with these systems.
The action of "always test, inspect for what you expect and document" provides a clear and concise means for implementing a sound CPAC system for you artifacts.Comment
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How fast time goes, it has been 2 years and 4 months since last posting on the subject of corrosion control & elimination of the "white rust" or aluminum oxides from bullion insignia.
Go here for a look:
http://s1151.photobucket.com/albums/...view=slideshow
at this link, the last 2 slides are the April 2010 dated treatment.
The insignia now sits outside of the CORETC VpCI 126 "blue" bag an dwill remain so as the insignia is now stabilized from further corrosion attack for the time being. OVer the next 6 months, monthly inspections are done to see if any new developing "white rust" or aluminum oxide develops. If so, renewed treamtent and back in a new blue bag as the old bag is beyond pull date.
I will be in contact with CORTEC engineers to find anythign they may have, a whie paper or technical report regarding the films they extrude for the zip bags and heat shrink use.
With this information and this date of Sept. 2012 the proof is positive at this point that the system works to relieve bullion of the white oxides that form when bullion is exposed to moisture.
For those pieces where the bullion is impacted with oxides that have built some distance from the base thread, if that is removed you might not like what you see because the shiny aluminum that is wrapped/attached to the base thread is lost in the corrosion process.
All you'd end up seeing then is the base thread, but you would have the attack of corrosion and further loss of the aluminum outer wrap stable from further corrosion attack.
For those who have insignia that have a high % of bullion remaining and are concerned that over time the loss will degrade your insignia, I would believe one would be successful in staving the attack and saving the remainder of the bullion for an extended period of time.
How long this time would be requires follow up inspections and treatment when needed or when the life cycle of the inhibitor wanes. In this case the recently applied inhibitor (CORTEC VpCI 239) has a 3 year life cycle.
The other factors are environment and storage habits as this plays into the cycle as well.
Additionally, for those who want more information, here is a technical manual produced by the USAF for storage of electronic systems. This manual came about as at the start of the introduction of VpCI technology for the USAF, this was is 1998.
I traveled to Anderson AFB in Guam. From that trip and then 3 years of work with the USAF, the deep mothball program was developed.
Over time, the manual had to be developed as more people around the world at USAF bases had to induct excess equipment into mothballing and turnover of personell in the USAF mandated continuity of the program.
The manual was then developed by the folks over at Warner Robbins & the Engineers at CORETC providing both in house, USAF and independent test results. Warner Robbins iswhere the USAF has their corrosion lab:
http://www.robins.af.mil/shared/medi...091006-037.pdf
With all of this, both films, CORETC VpCI 126, Blue bags and rolls of CORTEC extruded 126 film as well as MilCorr 10 mil heat shrink film and the CORETC VPCI spray products were used for their 5 year mothballing of excess gear. Through all of this, tests & monitoring were conducted as sensitive electronic equipment was stored as well.
If out gassing was an issue, USAF would state precautions. So here, first hand is information that all can see.
I will look for white paper/technical reports on this subject and I do invite anyone and all to post what they find for intelligent discussion.
I will keep providing up dates of the insignia and the "white rust" condition for forum members as time moves ahead.
In closing for now, is there any interest out there for this?
www.corrosioncops.comLast edited by Rich Moran; 09-02-2012, 02:52 PM.Comment
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Not sure how the link keeps on getting changed, here is the link again for the 3rd time:
http://s1151.photobucket.com/albums/...%20Mitigation/Comment
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So here it is 4 June 13, on the 69th anniversary of D-Day I again post on this thread. The last posting on this was several months back.
Since the last posting, the bullion insignia has been displayed without the benfit of the protective CORTEC VpCI package, and is still in excellent condition as the bullion oxidation has not returned.
You can see for yourself here:
http://s741.photobucket.com/user/ric...69186279891276
Instead of seeing this piece being destroyed by corrosion, the piece has been stabilized and is now going on 4 years. As a refresher, the climate I reside in is by far one of the most difficult on
the planet when it comes to rust and corrosion. Of late & over the last 2-3 years, we have had less days of tradewinds at a decrease of about 20% per todays Honolulu Advertiser. With less trade winds comes vog, which is air borne sulfuric dioxidefrom the states active volcano on the big island of Hawaii. Per NASA study, oahu gets 350 tons per day of vog as the big island itself has seen 1,200 tons per day.
This mixes with a chloride rich atmosphere due to ocean activity, and when the humidity goes up, metal is attacked in a way that some says I cannot believe what has happened to my car, truck, motorcycle etc.
We see Ford F100's within 2 years develop corrosion along the fire wall area, window trim and roofs at a rate that is really astounding. If a vehicle can go 10 years here without corrosion it is actually fantastic to see.
It all boils down to the fact, that anything left unprotected suffers due to Hawaii's atmospheric conditions.Last edited by Rich Moran; 06-04-2013, 06:29 PM.Comment
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