等离子喷涂镍基合金涂层内聚强度的截面划痕表征

制备了3类不同成分的等离子喷涂Ni Cr BSi涂层,利用截面大载荷划痕测试方法表征了涂层内聚结合强度,评价了涂层在油润滑条件下的滑动磨损行为,讨论了涂层内部残余应力、显微硬度、内聚强度与涂层耐磨性之间的内在关联.结果表明:在本文所用涂层沉积与划痕测试条件下,Ni Cr BSi涂层内聚强度的高低次序为Ni25Ni35Ni45,涂层显微硬度的高低次序与喷涂原始粉末硬度次序同为Ni25Ni35Ni45;涂层耐磨性与显微硬度间无对应关系,而与内聚结合强度关系密切,三种涂层耐磨性高低次序为Ni25Ni35Ni45;Ni Cr BSi涂层在低载荷条件下的磨损失效形式主要为磨粒磨损,随着载荷增加,涂层内部微小孔隙、裂纹等缺陷在残余拉应力和摩擦剪切力作用下诱发裂纹扩展并引发材料剥落,使疲劳剥落主导了涂层的磨损失效.

Bond Behaviors Characterization of the Plasma Sprayed NiCrBSi Coatings by Scratch Testing on Coatings Cross-Section

Three plasma sprayed NiCrBSi coatings were deposited on 1045 steel substrate. The cohesion bond strength of the coatings was characterized by cross-sectional scratch testing. The sliding wear behaviors of the coatings were studied under oil lubrication. Results indicate that the wear volume and the microhardness of plasma sprayed NiCrBSi coatings are not invariably linked. The wear resistance of the coatings ranking from the highest to the lowest is Ni25, Ni35 and Ni45. There existed a good correlation between the wear behavior and the cohesion of NiCrBSi coatings. The wear mechanism of the coatings included abrasive wear and spalling wear. The former was the dominant mechanism at lower load. By increasing load, spalling of splats of coating was dominant wear mechanism.