finishing.com -- The Home Page of the Finishing Industry
A website for Serious Education, promoting Aloha,
& the most FUN smiley you can have in metal finishing

HomeFAQsBooksHelpWantedAdvertiseForum
topic 13775

How to Alodine ADC12, 380, Castings, and Secondary Aluminum Alloys



A discussion started in 1996 & continuing through 2017

(1996)

Q. I have a problem with chromate conversion coating on 380 aluminum: I have a very trace amount of copper on the surface of parts when the they are put into use down the road. Anyone have any ideas? I am using a thin coating of chromate. Replating of copper? Corrosion of the alloy's copper?

Joe Hanke
engineer - San Jose, California


A. 380 has a lot of copper in it, about 3.5 percent, so I'd certainly assume that the copper is coming from the alloy, and immersion depositing. At this point there is probably dissolved copper in the chromating bath. Whatever you are doing in terms of rinsing after cleaning / etching /desmutting probably needs improvement; but I don't know if that alone can fix the problem, or if the longevity of your chromating solution will be limited by its picking up copper this way.

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


(2000)

A. My experience has shown that chromating solutions for use with aluminum alloys have to be discarded quite frequently. It usually comes concentrated and takes little to make up. Some good hand scrubbing, caustic etch, rinse, Preposit® 748, rinse and then chromate. This works great for me.

Hope this helps.

JASON JOHNSTON
- OTTAWA, ONTARIO, CANADA



(2000)

Q. I am looking for some information regarding Alodine 1000 and 1500. First the name and contact information for the manufacturer in the US.

Second, looking for information regarding the best method of measuring the thickness of Alodine on Aluminum die castings.

Lastly, any information regarding non-chromate chemical conversion processes for aluminum die castings (A380, 413.2, ADC 12, GD-AlSi9Cu3, GD-AlSil2(Cu)).

Thank you,

Kevin Yuskis
- Richmond, Virginia USA


(2000)

A. Alodine is a trademark of Henkel Surface Technologies. Find them on the web or ask your local plating process distributor if they handle Henkel.

I don't have a good answer for question #2, sorry, maybe someone else will. But it is a very thin (millionths of an inch, not thousandths) conversion coating rather than a topping (it converts the aluminum to a complex mixture).

Regarding substitutes, see www.jgpp.com/jtr-hugh.htm for a list of the most promising, and to learn the sad news that, when independently tested, no chromate substitute really holds up yet despite all the hype and the desperate search.

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey

Update Nov. 2006: The jgpp.com domain is still functional but the referenced page link is now broken. Progress has been made on this subject though, and there is now a MIL-DTL-5541 approved hex-free substitute called TCP licensed by the navy to CST-Surtec, Henkel, Luster-On, and Metalast.



(2004)

Q. I need yellow Alodize (chromate conversion) technical data for die casting aluminium (ADC12), which shall meet Mil-DTL-5541 [link is to free spec at Defense Logistics Agency, dla.mil], CLASS III.

Peter Hong
student - Nanhai, Guangdong, China


March 18, 2013

A. Hi Peter. To my knowledge there is no product called "Alodize". However, there appears to be a technical dictionary which claims --

ALODIZE: A process for bathing metal in hot Alodine solution to give it protective coating and surface for painting.

So I think this thread about "Alodining" ADC12 covers your topic. Good luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey




Q. We have been told that Alodine® can only be used with the so-called "pure" grades or primary aluminum alloys, and that it will not work with the secondary alloys, such as, 360, 380, etc., that are found in the pressure die casting industry. Is this true? I would appreciate hearing from anyone who can share their experiences of Alodining secondary aluminum alloys.

Don Wineman
- Asheville, North Carolina


A. Don, perhaps whoever told you this is not familiar with the diecasting business. We probably Alodine 90-95% of the aluminum castings we run and that would include A380, A360, ADC12, 413.2, etc. Now if you had mentioned anodize, your source of information would be correct.

Kevin Yuskis
- Richmond, Virginia


A. Alodine and other chromates and also anodizing may be applied to the casting alloys you listed. Only the surface preparation is different. In the case of the cast alloys the quality of the finish (either chromate or anodize) is a function of how much non-aluminum alloying ingredients we can remove from the surface, and different preparation for different alloys. Many job shops are only set-up for wrought alloys and when they try to process the casting alloys thru the same deoxidizer they leave alloying ingredients on the surface; then since we can only anodize aluminum, the presence of the silicon, copper, etc, interferes with the cosmetic appearance and the protection of the chromate or anodize oxide.

robert probert
Robert H Probert
Robert H Probert Technical Services
supporting advertiser
Garner, North Carolina

Editor's note: Mr. Probert is the author of Aluminum How-To / Aluminio El Como



March 15, 2013 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Hello,

We tried to do clear chromate per MIL-DTL-5541 on ADC-12 aluminum alloy casting.
We followed the same process as we do for extruded aluminum. The parts look blackish and we also see lot of big stains on the surface.

Can somebody help me what change in process is required to get a good finish? I heard that others had success and get good quality surface finish.

Thanks in advance.

PRITAM PATEL
- Randolph, Massachusetts, USA


March , 2013

A. Hi Pritam. We appended your inquiry to an existing thread which answers it. Diecastings contain silicon, copper, and other materials which will cause these problems if not removed from the surface with proper pretreatment chemistry. The etch and especially the desmut process that you are using are not adequate for castings. Please talk to your supplier about new chemistry for these steps. Good luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



March 31, 2013

Q. There are so many Alodining test available like Alodining 1000, 1200, 1201, etc. I just want to know which test is suitable for ADC-12 diecasting. Can anyone tell me?

ABHISHEK JAIN
Management - ALIGARH, UTTARPRADESH & INDIA


April 1, 2013

A. Hi Abhishek. Alodine is Henkel's trade name for their chromate conversion coating chemistry. Yes, it is confusing because there are many types depending on whether you need a light, low chemical resistance coating with good conductivity vs. a heavier more corrosion resistant coating where conductivity doesn't matter; and whether you intend to apply it by spray vs. immersion dip; and whether this is primarily a touch-up operation where you want a single-part concentrate for simplicity vs. a system where you can add replenishment chemicals to maintain a balanced system at lower cost; and whether you can use a hexavalent process or need to use trivalent. Hopefully you understand why people cannot answer your question without further info. Please tell Henkel or another supplier these additional details about your needs, and they will tell you which one to use.

By the way, I hope I'm not misunderstanding, because Alodine is not a "test", it's a conversion coating process. Good luck.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey



Black shade after chromating on ADC 12

October 15, 2013 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Hi friends

We have an issue of black shade on ADC12 DIECAST PARTS after chromating Alodine 1200.
The diecasted parts have black shade.
The diecasted are machined and glass bead blasted before chromating.
We have been observing that black shades remain after chromating.

Can anyone post your views in this regard?

Dinesh Pilakot
- COIMBATORE, TAMILNADU, INDIA


December 6, 2013

A. The issue is with your precleaning. Each of those alloys have either high Copper or Silicon, which when etched with a caustic solution will form a smut of black powder. You will need to use a more aggressive deoxidizer after caustic etch, one formulated to remove those elements. There are proprietary deoxidizers on the market, your Chromate supplier can help, or you could try a Nitric Acid/ Nitric-Sodium Bi-Fluoride Etch.

Paul Slater
- Cedar Rapids, Iowa, USA



Surface treatment problem on ADC 12 pressure die casting -- insufficient salt spray hours

March 11, 2015 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. Hi,
I am looking for a process/chemical to be used on ADC 12 castings to achieve minimum 160 hrs. salt spray life. I have tried different process/s but results are not satisfactory. May be because of some lubricant being used ( graphite based but shifted to water based during casting process). We have used Surtec chemicals but results are not satisfactory. Will shot blasting with Stainless steel balls help improving salt spray life? Please suggest a process to achieve 160 hrs. minimum salt spray life.

Varun Soni
- Faridabad, Haryana, India


March 2015

A. Hi Varun. We added your inquiry to this thread since your interest may be in chromate conversion coating, although I'm not really sure. You say you've tried different processes and you've tried Surtec brand chemicals, but it's not really clear to me what you've tried and what you haven't.

What cleaning regimen did you try to attempt to remove the graphite? And did you try chromate conversion coating after that cleaning? Was the chromate the final surface, or did you try painting or powder coating it? And how many hours of salt spray are you obtaining? Thanks.

Regards,

Ted Mooney, finishing.com
Teds signature
Ted Mooney, P.E. RET
finishing.com
Pine Beach, New Jersey


March 17, 2015

Q. Hi,
ADC 12 parts after nitric acid treatment gets blackish in colour. Is it the graphite based lubricant present in pores during casting process or is it due to presence of high copper? Will short blasting with SS shorts before treatment will solve this problem?

13775-1a  13775-1b  13775-1c  13775-1d

Need salt spray of minimum 160 hours with trivalent based chromotising. Please suggest a process. No coating is allowed -- only chromate passivation.

varun soni [returning]
- Faridabad, Haryana, India



13775-2
March 17, 2015

Sir I want the procedure of how to get the silicon and carbon percentage.

tukaram budde
making aluminium alloys - aurangabad india maharastra



Alodine 5200 on ADC12 extreme discoloration problem

June 23, 2017

Q. We have manufactured large Die Cast ADC12 chassis and steel shot blasted them, 30% HCL and Alodine 5200 post treatment that cosmetically well but not RoHs friendly. Now we are doing smaller modules and we glass bead and decrease and then treat with Alodine 5200 but the color has dissimilar wave patterns in it, like the flow of the material and is very ugly. These need to cosmetically look good but not perfect. We tries acid washes pre-treatments but still the same effect. We need some treatment that is RoHs and does not effect the thermal or electrical properties... also not expensive. Any suggestions?

Stuart Ringwald
Engineer - Houston, Texas, USA
  ^- Privately contact this inquirer -^


July 29, 2017

A. The problem with ADC12 is the high copper and silicon content, which don't chromate and can form a smut during etching or acid pretreatment. Clear chromate or anodize will not cosmetic on copper containing castings.

Appearance can be improved by using a fluoride based etch with nitric and HF or ammonium bifluoride to remove the copper and silicon, but cosmetic can still be an issue as the composition is different everywhere in the casting due to cooling rate. Avoid alkaline etching, this will only remove aluminum and concentrate the impurities.

I have also found better results switching to A360 grade casting material that does not contain copper.

Alex Peterson
- Rochester New York



This public forum has 60,000 threads. If you have a question in mind which seems off topic to this thread, you might prefer to Search the Site

ADD a Q or A to THIS thread START a NEW THREADView This Week's HOT TOPICS

Disclaimer: It's not possible to diagnose a finishing problem or the hazards of an operation via these pages. All information presented is for general reference and does not represent a professional opinion nor the policy of an author's employer. The internet is largely anonymous & unvetted; some names may be fictitious and some recommendations may be deliberately harmful.

  If you need a product/service, please check these Directories:

JobshopsCapital Equip. & Install'nChemicals & Consumables Consult'g, Train'g, SoftwareEnvironmental ComplianceTesting Svcs. & Devices


©1995-2017 finishing.com     -    Privacy Policy
How Google uses data when you visit this site.