Posted by Gordon England on January 22, 2004 at 18:03:26:
In Reply to: co-efficient of friction of thermal sprayed ceramic posted by Bill Ferree on January 21, 2004 at 16:33:13:
: I have this data for carbide, but I need the data, actually, for chrome oxide ceramic (plasma sprayed).
Hi Bill
Problem with coefficient of friction value is that it varies appreciably with such factors as load, speed, temperature, surface finish, cleanliness and lubrication of the mating surfaces. A quoted value of coefficient of friction is really only useful when comparing to other values obtain under exactly the same testing conditions. The info below really is only useful when comparing materials from the same test conditions.
I remember some wear tests where a molybdenum coating gave results around 0.3 - 0.4 the sample was then sent away for machining to evaluate a finer surface finish. Unknown to us at the time, the coating was ground using a lubricant and on re-testing got values around 0.02 which was better than the PTFE coated samples we had tested. Being uncomfortable with these values the molybdenum sample was then cleaned and degreased, but still gave the very low result. The test was then repeated with a new freshly coated and dry finished sample and results return to around 0.3. Just goes to show the effect of minute levels of contamination.
UCAR Union Carbide data:
High load. low speed, dry rubbing test.
LC-5 (chromium oxide + 20% aluminium oxide)
Haynes Alloy 25 - 0.22
440C stainless steel - 0.27
Against itself - 0.28
Wet abrasion wear test (water)
GA Meehanite - 0.08
Ni-Resist - 0.1
Ball race steel En31 - 0.14
Against itself - 0.09
Hope this helps and thanks for your input into the forum.
Regards Gordon
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