Rolling contact fatigue failure mechanisms in plasma and HVOF sprayed WC-Co coatings
Rolling contact fatigue failure mechanisms in plasma and HVOF sprayed WC-Co coatings
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DOI：
10.1016/s0043-1648(97)00138-5
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发表时间：
1997-11
期刊：
影响因子：
5
通讯作者：
R. Nieminen;P. Vuoristo;K. Niemi;T. Mäntylä;G. Barbezat
中科院分区：
文献类型：
--
作者：
R. Nieminen;P. Vuoristo;K. Niemi;T. Mäntylä;G. Barbezat
采用双辊式滚动接触疲劳试验机研究了名义成分为WC-12%Co、WC-10%Co-4%Cr和WC-17%Co的热喷涂WC-Co涂层在无润滑纯滚动条件下，在420-600 MPa赫兹接触应力下的滚动接触疲劳行为。涂层的制备通过大气等离子喷涂（APS）和两个高速火焰喷涂（HVOF）工艺。APS喷涂WC-12%Co涂层的RCF损伤主要是由于涂层内剥落和裂纹网络的形成而导致的表面粗糙度增加。HVOF喷涂WC-12%Co和WC-10%Co-4%Cr涂层在接触表面形成垂直、线性裂纹或点蚀。在HVOF喷涂涂层中形成的凹坑明显少于APS喷涂涂层中发现的凹坑。HVOF喷涂WC-17%Co涂层的RCF性能最好，涂层表面粗糙度基本不变，没有裂纹形成，接触表面只有少量凹坑。该涂层在RCF测试中对失效形成的良好抵抗性是由其更高的延展性和断裂韧性引起的，这是由于与其他涂层相比更高的金属粘合剂含量。其他特征，例如少量的脆性Co-W-C碳化物和致密的微观结构也被认为对于耐RCF涂层是有益的。
The rolling contact fatigue (RCF) behaviour of thermally sprayed WC-Co coatings with nominal compositions of WC-12%Co, WC-10%Co-4%Cr and WC-17%Co was studied with a two-roll configuration roll-against-roll testing apparatus under 420–600 MPa Hertzian contact stresses in unlubricated pure rolling conditions. The coatings were prepared by atmospheric plasma spray (APS) and two high-velocity oxyfuel (HVOF) spray processes. In the APS sprayed WC-12%Co coating the RCF damage was dominated by an increased surface roughness due to spallation of flakes and a formation of a network of cracks within the coating layer. HVOF sprayed WC-12%Co and WC-10%Co-4%Cr coatings were damaged either by the formation of vertical, linear cracks or pitting of the contact surface. The formation of pits in the HVOF sprayed coatings was significantly less than that found in the APS sprayed coatings. The HVOF sprayed WC-17%Co coating showed the best RCF behaviour among the studied coatings with unchanged surface roughness, no formation of cracks and only a few pits were found on the contact surface. The good resistance of this coating against formation of failure in the RCF testing is caused by its higher ductility and fracture toughness due to a higher metallic binder content in comparison with the other coatings. Other characteristics such as a low amount of brittle Co-W-C carbides and a dense microstructure are also believed to be beneficial for a RCF resistant coating.