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利用超音速火焰喷涂技术在Ni718合金表面制备WC-17C0涂层,对喷涂后的试样进行150℃,3 h和300℃,3 h保温热处理,利用Almen试片曲率法计算不同热处理条件下涂层中的残余应力,用反复弯曲试验测试试样的疲劳寿命,分析残余应力对试样疲劳寿命的影响。结果表明,在疲劳循环过程中,裂纹在涂层中萌生并向涂层/基体界面处扩展,最后扩展至基体内部形成最终断裂。涂层中的残余压应力能够抑制疲劳裂纹的产生和扩展。经过保温处理后涂层中的残余压应力降低,导致试样的疲劳寿命随热处理的温度上升而下降。
The WC-17C0 coating was prepared on the surface of Ni718 alloy by supersonic flame spraying. The sprayed samples were heat-treated at 150 ℃, 3 h and 300 ℃ for 3 h. The curvature of Almen specimen was calculated under different heat treatment conditions Layer residual stress, repeated bending test test the fatigue life of the sample, the residual stress on the fatigue life of the sample analysis. The results show that during the fatigue cycle, cracks initiate in the coating and propagate to the coating / matrix interface, finally expanding into the matrix to form the final fracture. Residual compressive stress in the coating inhibits the generation and propagation of fatigue cracks. The residual compressive stress in the coating decreases after the heat treatment, resulting in the fatigue life of the sample falling as the temperature of the heat treatment increases.