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Hard chrome plating fails CASS test

We are using hard chrome rods for shock absorbers & our corrosion resistance is not crossing 24 hrs CASS (copper accelerated acid acid salt spray) test, rating 10. Could you please suggest that how can we increase this corrosion resistance to 48 hrs by same hard chrome process?

Ashish Rikhie
Engineering mfgr. - Bangalore, Karnataka, India
2004

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First of two simultaneous responses --

One of several courses of action: no-brightener nickel underplate. How thick? Try 0.0003" and above. Adjust chrome process accordingly.

Guillermo Marrufo
Monterrey, NL, Mexico
2004

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Second of two simultaneous responses --

You have not provided very much information for us to consider. What type of plating bath are you using? What is the thickness of the plating? What is crack density that is specified? What is the crack density of the parts that are failing the CASS test? What is the surface finish of the failed parts? How is this surface finish obtained (what type of polishing is used?)? Low thickness is one reason for poor performance, as is poor surface quality due to bath contamination, grinding defects, etc.

Toby Padfield
Automotive suspension modules - Michigan
2004

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2004

Mr Rikhie,

If you are doing Direct Hard chrome over the base consider the following.

- Plate Semi bright Sulfur free Nickel to a thickness of 20 to 25 microns over the base metal first.
- After rinses and 10 % sulfuric activation , plate Chrome as usual.

This ought to shake up your CASS test chamber. Good Luck

Asif Nurie [deceased]
- New Delhi, India
With deep regret we sadly advise that Asif passed away on Jan 24, 2016

Ashish,

Tell us the standard for the test and also tell us how you pretreatment and plate the test pice, let us also know the parameters in your line for chrome.

Regards

Anders Sundman
4th Generation Surface Engineering
Consultant - Arvika,
Sweden
2004