爆炸喷涂WC-12%Co涂层的滑动磨损性能

Sliding wear resistance of detonation-gun sprayed WC-12%Co coatings

采用爆炸喷涂技术制备纳米和普通WC-12%Co涂层,用往复试验机对涂层的干滑动磨损性能进行了研究,分析了涂层磨损前后的形貌、结构及成分变化。结果表明:相同的喷涂条件下,WC-12%Co纳米涂层比普通涂层结构均匀、致密,但碳化物分解严重。尽管纳米涂层与普通涂层具有相近的硬度,但普通涂层的耐磨性优于纳米涂层,尤其是在重载条件下。普通涂层的磨损机制为微切削;纳米涂层在轻载(10 N)下,以塑性变形为主要磨损机制,随载荷增加至30 N,纳米WC粒子不能起到阻抗陶瓷球对磨副的磨削作用,而是随粘结相一起被去除,同时由于纳米涂层脱碳导致的层间结合薄弱,在滑动磨损中易发生成片剥落,耐磨性大幅下降。

WC-12%Co coatings were deposited by detonation-gun spraying with nano composite and conventional powder feedstock. The sliding wear resistance of the coatings was investigated using reciprocating tester under dry sliding wear conditions. The morphology, microstructure and composition change were analyzed. The results show that nanostructured coatings have more homogeneous and denser microstructure than their conventional counterparts under the identical spraying conditions, in spite of more decomposition of carbide in nano composite powders. The wear resistance of the conventional coatings is better than that of nanostructured coatings in the same microhardness level, especially at the higher load. The wear mechanism of conventional coatings is microcutting. Concerning nanostructured WC-Co coatings, the wear is dominated by the plastic deformation under load of 10 N. With increasing the applied load, nano WC particles as anti-wear phase are removed from the coating surface together with the binder phase. In addition, there is delamination removal at weak interface due to decarhurization. The two reasons above lead to lower wear resistance of nanostructured coatings at the higher load.