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Weak adhesion of brake lining to Aluminum after Alodine treatment



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Tutorial:
(to provide context, hopefully helping readers more quickly understand the Q&A's)

"Alodine" is Henkel's tradename for their line of chromate conversion coatings for aluminum. "Iridite" is MacDermid's tradename for theirs. The process is sometimes called "chem-filming of aluminum". The most common standard describing/dictating their use is MIL-DTL-5541.

Current postings:

January 3, 2022

Q. We need to paste brake lining on aluminum body after Chromating the aluminum body. We are using Araldite 64 as glue. Adhesion is good and qualifies to the standard if done without Chromating the aluminum body. But after Alodine treatment adhesion is not good and lining comes out with about 50% force than Standard necessary before pasting.

Abdul Rehman Aizaz
- Karachi, Pakistan
^


January 2022

A. Hi Abdul. Chromate coatings are subject to dehydration if dried at too high a temperature or subjected to other operations which might disturb them before the 24-hour cure time. They are also subject to shearing, especially if too heavy.

Many people are doing it, but even still, chromate conversion coating might not be the best/only aluminum treatment before adhesive bonding. Your inquiry is attached to several others on this general subject, and you might or might not find a different process to be better suited to this application :-)

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
^


January 5, 2022

A. Alodine should help adhesion if applied properly, so you should look at how you apply the chem film. Do not heat over 140 °F or put it on very heavily. Heating over 140-160 will dry the film out and destroy adhesion. Putting on a very heavy dark film will also destroy adhesion. Just as a note a trivalent material will be less susceptible to drying out and should handle higher temperatures. Hope this helps

drew nosti
Drew Nosti, CEF
Anodize USA
supporting advertiser
Ladson, South Carolina
anodizeusa1
^




Closely related Q&A's, oldest first:

References/Information on P2 Etch Process & Alodine

1999

Q. I am new to the aluminum finishing business and could use some technical information on the P2Etch Process and the Chemical Conversion Coating process (Alodining). Also would like to network with other folks concerning chemical suppliers, equipment, techniques, problem-solving.

Tomaszewski
Manufacturing - Cadillac, Michigan, USA
^


"Adhesive Bonding of Aluminum Alloys"
by Edward Thrall
from Abe Books
or

Affiliate Link
(your purchases make finishing.com possible)

1999

A. Hi Tomaszewski ,

I suggest that you contact , Mr Dave Hunt of Stone Chemical, Naperville , Illinois and use my name as a means of introduction . You will find Dave a very knowledgeable fellow who networks very well. best regards John . C . Tenison - Woods

John Tenison-Woods
John Tenison - Woods
- Victoria Australia
^


1999

A. I'm not familiar with the P2 etch myself, but chromate conversion coating of aluminum is covered in specification Mil-C-5541 [link is to free spec at Defense Logistics Agency, dla.mil].

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
^


"Adhesive Bonding"
by L.H. Lee
from Abe Books
or

Affiliate Link
(your purchases make finishing.com possible)

1999

A. The P2-etch process was developed and patented by Picatinny Arsenal as an alternative to the FPL etch for adhesive bonding to aluminum alloys. Sulfuric Acid, conc (sp. gr. 1.84) 370 g Ferric Sulfate, 75% 150 g Dilute to 1 liter with deionized water Temperature 150 °F Time 12 min

Bill Park
- Palo Alto, California
^


1999

A. The P2 etch solution is described in ASTM D2651 [affil. link to spec at Techstreet] Standard Guide for Preparation of Metal Surfaces for Adhesive Bonding.

Ward Barcafer, CEF
aerospace - Wichita, Kansas
^


1999

A. The original Alodine is a process that been invented some 70 years ago. The original company for it is Henkel Surface Technology.

yehuda blau
Yehuda Blau
YB Plating Engineering and Quality - Haifa Israel
^



We merged some threads on this page. Please forgive what may look like disrespect towards earlier responses; they probably weren't there :-)



Adhesive Use on Conversion Coated Aluminum Surfaces

1999

Q. The Handbook of Aluminum and Aluminum Alloys states that, "Because of their low strength, conversion coatings should not be used on surfaces to which adhesives will be applied". Is there any information that supports or contradicts this statement? We have gone through extensive testing of 3M TS-230 Hot Melt on an Alodined aluminum surface and have seen no problems. I would like to be able to proceed based on our testing, but I don't want to violate proven industry practices. Is bonding to Alodined aluminum acceptable?

Jeff Groce
- Dallas,Texas
^


1999

A. At one of the companies I worked for, we applied an adhesive primer to a chem-filmed, (chromated) 1100 alloy 5 mil thick aluminum foil surface. We qualified the foils by lap shear testing at cold, ambient and elevated temperatures. The results were as good as FPL etched, adhesive primed lap shear coupons which were bonded as controls.

Ward Barcafer, CEF
aerospace - Wichita, Kansas
^


1999

A. Dear Jeff Your statement show that DO NOT BELIEVE EVERY BOOK, especially books in surface finishing. The developments and innovation in this area is so fast that from the beginning time of writing the book to the end of period there are changes . This what is making our occupation so fascinating and interesting. You are doing the same as thousands of factories are doing and give step elevation to the quality of your products . Yours

yehuda blau
Yehuda Blau
YB Plating Engineering and Quality - Haifa Israel
^


1999

A. It sounds like we're all saying, "if it works, don't try to fix it." We recently had a "think outside the box" training program in our R & D Dept., where we essentially learned not to assume that many of those "cast in stone" rules can't be broken. One thing I like about this business is that most successful finishers use very little exact "cast in stone" science and a lot of logic and common sense. Considering that there are probably a zillion types of adhesives out there with varying amounts of adhesive strength from Post-its to holding rocket parts together in outer space, making a blanket statement like the one in the handbook is naive and close-minded on the part of whoever made it. The statement may be true for some very high strength adhesives where anodize may be superior over conversion coating, but conversion coatings should work with many adhesives.

As long as your successful tests are representative of the actual real-life application of the product, then you've proven that it works, so why not go for it?

phil johnson
Phil Johnson
- Madison Heights, Michigan
^



Aluminum bonding for high temperatures

2002

Q. I am looking for an adhesive to bond aluminum to aluminum, that will with stand average pressure, temperatures over 350 °F and will not be effected by automotive oils.

John Briner
- Clarksburg, ON, Canada
^


2002

A. You might want to look at a new process developed by The Welding Institute in England, friction stir welding. If your geometry isn't too complex, and you can find someone who can do it for you (it is new), it provides a welded junction without any heat distortion of the parts. There was an article on it in Advanced Materials and Processes early last year. There will be some presentations on the technology at this year's Aeromat meeting.

jim treglio portrait
Jim Treglio - scwineryreview.com
PVD Consultant & Wine Lover - San Diego,
California

^



1842A Aluminum finish?

2003

Q. Can anyone please guide me to find more details of 1842A chemical coating on aluminum?

My problem is that I am trying to verify a part that is supposed to have 1842A coating on aluminum part. So far, I have not been able to establish the details of this coating.

Regards,

Dale Sahota
-Calgary, Alberta, Canada
^


"Handbook of Aluminum Bonding Technology and Data"
by J. D. Minford
from Abe Books
or

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(your purchases make finishing.com possible)

2003

A. It could be an SAE standard (recommended practice): SAE Standards. Document Number: ARP1842 [affil. link to spec at Techstreet] Date Published: July 1984 Title: Surface Preparation for Structural Adhesive Bonding, Aluminum Alloy and Low Alloy Steel Parts. This recommended practice describes the materials and procedures for cleaning aluminum allow detail parts and low-alloy steel parts (other than corrosion resistant steel) prior to structural adhesive bonding operations. The surface treatments described here have proven effective for producing a suitable surface for application of adhesive primers, films, or pastes prior to structural adhesive bonding operations. https://www.sae.org/servlets/productDetail?PROD_TYP=STD&PROD_CD=ARP1842

Ken Vlach [dec]
- Goleta, California

contributor of the year Finishing.com honored Ken for his countless carefully researched responses. He passed away May 14, 2015.
Rest in peace, Ken. Thank you for your hard work which the finishing world, and we at finishing.com, continue to benefit from.

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