| Abstract |
| Air plasma spray coatings of three different WC-12%Co powders based on the powder manufacturing methods were conducted. Mixed powders composed of S&F (Sintered and Crushed) WC-12%Co which revealed the best wear resistance in this study and NiCrSiB with different ratio(25:75(B1), 50:50(B2), 75:25(B3)) were also evaluated, The best wear resistance of S&F WC-12%Co coating was mainly due to its high hardness related with large amount of homogeneously and/or uniformly distributed total carbides and low porosity. The wear resistance of blend coatings increased with increasing WC-12%Co weight percent but was not noticeably improved compared to that of WC-12%Co coatings. The dominant wear mechanisms of WC-12%Co coatings were combined actions of adhesive wear, carbide particle fragmentation, and tribo-film formation by material transfer on which fatigue crack formed and propagated under repeated loading leading to delamination. In the case of blend coatings, the dominant mechanism of B1 and or B2 coating was observed to be the following sequence : abrasive wear(ploughing or scratching) in the soft NiCrSiB coating layers → carbide extrusion and fragmentation → crack formation and propagation at the rear of abrasive mark →separation of coating layers and delamination as well as adhesive wear (adhesion). But, B3 coating which contained the 75wt% of WC-12%Co showed both the wear mechanism of B1 and or B2 coating and that of WC-12%Co coating. |
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| Key Words |
| Plasma spray coating, Powder manufacturing method, Wear resistance, Adhesive wear, Abrasive wear, Carbide particle fragmentation, Crack, Delamination |
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