Suppose I test sliding wear resistance of a nanocomposite material using a pin on disc tribometer. Now once I get the specific wear rate can I use it to predict the wear rate of the same material when it is used as a coating over a substrate. Is there any standard to do the same ?
Basically, all anorganic coatings have quite different properties compared to compact materials having the same compositions. This applies as well as to metallic as to ceramic layers and also to cermets. Only the metallic layers produced by build-up welding are comparable to castings of the same composition.
The ceramic coatings, for example plasma sprayed coatings of Al2O3, Cr2O3 and ZrO2, or PVD-coatings of TiN and CrN, have very different properties compared to corresponding ceramics. Cermet coating WC-Co, applied by means of HVOF/HVAF are also extremely different from hardmetal WC-Co and so on.
So, you can not transfer the properties (e.g., wear resistance) of the compact material to coating.
Vadim, Thanks for your inputs. Let me take the example of polymer nanocomposite coating which is used as an anti corrosive coating. If I need to test the wear resistance of the coating, here in my college I have pin on disc tribometer for which the specimen size required is 10 mm in diameter and 30 mm in length. I have no other facility here other than to apply coating on a flat substrate using film applicator and once cured cut it into required sizes for pin on disc wear testing. But for the area if exposure of the pin, I think the coating would wear out too fast even for minimal parameter setting. Very difficult to measure the weight loss in such cases. There is actually a ASTM standard for coating abrasive wear measurement called Taber abrader which requires a flat specimen which is wide enough; but that facility I don't have here in my university. So my plan was to measure the wear resistance of PIN made completely out of polymer nanocomposite and correlate that to wear resistance of coated PIN. I understand the process used for fabricating castings and coatings are different. In my case since I am using film applicator for coating and casting for preparing PIN, can I correlate these two results ?
Dear Murali,
In my first answer, I wrote about inorganic materials. Polymeric layers and compact polymers resemble each other much more than layers and compact materials of inorganic materials because manufacturing processes for polymer layers and bulk polymers are similar. If your polymer layers are thicker than 100 μm, a comparison with the piece of the same polymer is justified.
Okay. Mine is above 100 micrometer. I will go with conduction of wear testing of PIN samples made out of the nanocomposite then
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