A Tough Adhesion Test

Q. We plate tubular steel with nickel for one of our important customers. The adhesion test we use requires bending of the tubing at right angles. If the nickel does not flake in the area of the bend, the plating passes. If there is extensive flaking the plating fails. I don’t think this is a reasonable test. Do you? S. G.

A. My direct answer is, no, this is not a reasonable test. I cannot imagine, even if your nickel plating is performed in a manner to give you the most ductile deposit possible, that you will have much success in passing the test. I would expect that there would be considerable cracking of the plate even in the best of circumstances. Also, based on your description its seems to me that judging good results is at best subjective. What distinguishes between extensive flaking and minimal flaking?

An alternative test that is sometimes used is to take a piece of the plated tubing and flatten it in a press. A small amount of cracking and flaking will occur. This test is not as rigorous but in my opinion will give results that you and your customer can live with.