Letter 18002

Hard Chrome Plating Bond Strength Testing Methods and Other Related Literature [India] 

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Dear sir:

We are working on coating the cast iron engine cylinder with the hard chrome and now we would like to know if there is a way that we can measure the adhesion of the coating. Thank you for your attention & your prompt response will be highly appreciated.

Sincerely yours,

Harsh Kumar
MINISTRY OF RAILWAYS - PUNJAB, INDIA

Others may have a better idea, but I don't know how to test it directly. You can however plate a sample of the same material at the same time, but in an easier to work with geometry, and do an Ollard test. If you can find nothing about Ollard on the net, I can expound.

 
Ted Mooney, P.E.
finishing.com Inc. - Brick, NJ

We have seen references to The Ollard test and the Modified Ollard test and have never been successful in obtaining any information on the subject.

We supply HVOF applied coatings on chilled cast iron and have used ASTM C-633-79 to measure bond strength.

Can you please forward or refer us to any information on the Ollard test?

Could you also perhaps speak to the difference between the Ollard and the modified Ollard.

Does either apply or transfer to HVOF coatings or are they specific to chrome or certain materials and is the test specific to a certain substrates

Thank you,

David Antoniazzi
- Torrington, CT, USA

Hi,

I'm a PHD student in mechanical science, and I'm also looking for some information on the ollard test. I would be really grateful if you were able to send me some details on it.

Many thanks,

David MOULIN
- Metz, France

A reason why you are finding it hard to track down this stuff is that the test is very, very old. The Ollard test is from 1925 and the modified Ollard test (by Knapp) from 1949. You need access to a computerized literature search to find references about it, not a web search engine, and then you need access to the documents that the abstracts reference. Hopefully extracting one quick sketch each from ASM's "Course 22 - Electroplating" and the April 1977 issue of Metal Finishing is 'fair use' rather than something the copyright holders will object to. They show, respectively, the Ollard test and the modified Ollard test. The original test was applicable only to plating onto a round bar which is then machined down to 1" diameter, whereas the modified test can be used on rectangular test panels and involves less machining and setup.

In either case the jig is put into a tensile tester (maybe actually a compressive tester), and then a calculation is made based on the cross sectional area. I haven't actually seen these tests run, but the advantage of these tests over competing adhesion tests is that they measure the actual tensile strength of the bond. Good luck.

Ted Mooney, P.E.
finishing.com Inc. - Brick, NJ

 

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