基于正交试验的超音速火焰喷涂WC-12Co涂层抗冲蚀性能研究

采用超音速火焰喷涂(high-velocity oxygen-fuel, HVOF)技术制备WC-12Co涂层，利用扫描电子显微镜(scanning electron microscope, SEM)、能谱仪(energy dispersive spectrometer, EDS)表征粉末、磨料、冲蚀前后涂层表面/截面的微观形貌和元素变化.设计正交试验并利用冲蚀试验机分析冲蚀距离、冲蚀角度和冲砂量对涂层冲蚀率的影响，探讨了涂层冲蚀机理.结果表明：WC-12Co涂层组织较为均匀、存在少量孔隙，涂层与基体间的结合方式以机械结合为主.极差和方差分析发现，当前工况下冲蚀距离对涂层冲蚀率的影响最为显著、冲蚀角度次之、冲砂量最小；30°冲蚀时冲蚀率最小、60°次之、90°最大.相对于高角度冲蚀，WC-12Co涂层具有较优的抗低角度冲蚀能力.30°冲蚀时涂层冲蚀机理为微观切削和犁削损伤，并伴有局部的脆断和剥落；90°冲蚀时为正向锤击作用引起的脆性断裂和片状疲劳剥落，剥落坑深度远大于30°冲蚀时的切削和犁沟深度，涂层损伤更为严重.

Study on erosion wear resistance of HVOF-sprayed WC-12Co coatings based on Taguchi method

WC-12Co coating was prepared by high-velocity oxygen-fuel(HVOF)technology. SEM, EDS were used to characterize the micro-morphology, element distribution and chemical composition of the surface/cross section of the coating before and after erosion. The Taguchi Design of Experiments(DOE)techniques and the erosion tester were used to analyze the effects of erosion distance, impact angle and abrasive mass on the erosion rate of the coating, and the erosion mechanism of the coating was discussed. The results show that the microstructure of WC-12Co coating is uniform and there are a small amount of pores. The bonding mode between coating and substrate is mainly mechanical bonding. The range and variance analysis show that under the existing erosion conditions, the erosion distance has the most significant effect on the erosion rate of the coating, followed by the impact angle and the abrasive mass, and the erosion rate is the smallest at the impact angle of 30°, followed by 60°and 90°. Compared with high impact angle, WC-12Co coating has excellent resistance at low impact angle. The erosion mechanism of the coating at the impact angle of 30° is cutting and ploughing damage, accompanied by a small amount of brittle fracture and spalling, and brittle fracture and fatigue spalling caused by positive hammering at 90°. The depth of peeling pit at 90° is much greater than that of cutting and ploughing at 30°, and the damage is more serious.