Posted by Gordon England on February 04, 2003 at 15:19:37:
In Reply to: Coating onto nitriding steel posted by Papapanos George on February 03, 2003 at 10:02:47:
: Good morning
: I would like to now why is have not good bond properties when we spray (arc,plasma,hvof) onto nitriding steel and we must removed the nitriding layer before spraying.
: Thank you
1. Nitrided surface is very hard and it is difficult to get a good grit blast etch/profile to anchor the coatings.
2. Some bond coat materials like molybdenum are not self-bonding to nitrided surfaces (particularly if white layers are retained)
To be successful in applying coatings to nitrided surfaces you will need to ensure a good sharp grit blast profile by using alumina or silicon carbide grit at high pressure.
Nickel aluminium bond coat materials are self-bonding to nitrided surfaces (removal of any white layer recommended)
Adhesion will not be as good as a soft non-nitrided steel, but should be adequate for many applications.
Regards Gordon
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