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为了研究不同涂层厚度对热喷涂件疲劳性能的影响,应用火焰热喷涂技术在40Cr基体上制备出不同厚度的Ni60A自熔性粉末合金涂层。采用XRD、SEM、EDX等分析手段分析涂层表面的物相与断口微观组织结构。用电液伺服高频疲劳试验机测试喷涂试样及基体试样的疲劳寿命。结果表明:对所设计试样而言,其合理的涂层厚度为0.25 mm;在2 min时间长度的重熔保温后,Ni60A涂层表面主要由Cr7C3、Ni、Cr3Ni5Si2、CrB、Ni3B等相组成;涂层厚度合理时,涂层表面及界面相对于涂层中间部分承受较大的轴向拉压载荷,热喷涂件的拉压疲劳寿命在合理的重熔条件下,高于基体试样的疲劳寿命;当涂层厚度大于0.25 mm时,热喷涂件的拉压疲劳寿命随厚度的增加而呈现总体下降的趋势,热喷涂件的拉压疲劳寿命与涂层中非金属颗粒及孔隙的数量及平均大小密切相关。
In order to study the influence of different coating thickness on fatigue properties of thermal sprayed parts, different thickness Ni60A self-fluxing powder alloy coatings were prepared on 40Cr substrate by flame thermal spraying technique. The phase and fracture microstructure of the coating surface were analyzed by XRD, SEM and EDX. The fatigue life of sprayed specimens and matrix specimens was tested with an electro-hydraulic servo high-frequency fatigue tester. The results show that the reasonable coating thickness is 0.25 mm for the designed sample. After remelting for 2 min, the surface of Ni60A coating mainly consists of Cr7C3, Ni, Cr3Ni5Si2, CrB, Ni3B and other phases ; When the thickness of the coating is reasonable, the surface and interface of the coating will bear larger axial tensile load with respect to the middle part of the coating, and the tensile fatigue life of the thermal spray coating under reasonable remelting conditions is higher than that of the matrix specimen Fatigue life; when the coating thickness is greater than 0.25 mm, the thermal fatigue life of the thermal spray coating tends to decrease with the increase of the thickness. The tensile fatigue life of the thermal spray coating and the number of non-metallic particles and pores in the coating And the average size is closely related.