WC-17Co粉末密度对涂层力学性能及残余应力的影响

Effect of WC-17Co Powder Density on Coating Mechanical Properties and Residual Stress

摘要:

选取3种不同密度的WC-17Co粉末，采用超音速火焰喷涂法制备厚度为0.3 mm的涂层。通过扫描电镜观察分析了3种涂层的孔隙率，采用压痕法测量了涂层的努氏硬度与弹性模量，同时采用剥层法对不同密度粉末制备的WC-17Co涂层残余应力进行了测试与计算。结果表明，涂层孔隙率随WC-17Co粉末密度的增大而增大，涂层的努氏硬度、弹性模量均随WC-17Co粉末密度的增大而减小。WC-17Co涂层内部存在的残余应力表现为压应力，且应力值随涂层厚度的增大而增加，在临近涂层-基体界面处迅速减小。涂层残余压应力最大值随WC-17Co粉末密度的增大而增加：粉末密度为11.52、12.86、13.49 g·cm^-3所制备的涂层残余应力最大值分别为-798、 -986和-1120 MPa。

Abstract:

Three kinds of WC-17Co powders with different densities were selected as starting material, and a coating with 0.3 mm in thickness was prepared by high velocity oxygen fuel (HVOF) method. The porosity of the three coatings was analyzed by SEM, the Knoop hardness and Young's modulus of the coatings were measured by indentation method. At the same time, the residual stress of the WC-17Co coating prepared by powders with different densities was measured by layer-stripping method. Results show that the porosity level of the coatings increases with increasing WC-17Co powder density, while the Knoop hardness and Young's modulus of the coatings decrease with the increase of powder density. The residual stress existing in the WC-17Co coating appears as compressive stress, which increases with the increase of the coating depth, and then decreases rapidly near the coating-substrate interface. The maximum residual stresses of the coatings deposited with powder density of 11.52, 12.86 and 13.49 g·cm^-3 are -798, -986 and -1120 MPa, respectively.