NiCrWMoCuCBFe涂层的制备及其力学性能研究

目的 探究NiCrWMoCuCBFe涂层的微观组织结构、物相组成及其力学性能。方法 通过霍尔流速计表征了喷涂粉末的流动性和松装密度，采用超音速火焰喷涂在316L不锈钢表面制备了NiCrWMoCuCBFe涂层，利用SEM、EDS分别对喷涂粉末的形貌、涂层的组织结构以及粉末和涂层中的元素组成进行了表征，采用XRD、Raman分析了涂层中的物相，使用显微硬度计及万能材料试验机考察涂层的硬度、结合强度和抗弯强度，并分析了涂层的断裂失效机理。结果 NiCrWMoCuCBFe喷涂粉末具有良好的流动性，在喷涂过程中没有发生严重的氧化现象。通过超音速火焰喷涂制备的NiCrWMoCuCBFe涂层具有致密的层状组织结构，其物相主要是Ni基固溶体，但是也出现了少量的NiO和Cr2O3。此外，涂层的截面硬度与表面硬度相当，约为600HV300 g，且涂层与316L不锈钢的结合强度较高，大于70 MPa。三点弯曲试验中，持续加载至载荷为1800 N，应变为(4.81±0.3)%时，涂层达到强度极限，产生明显的塑性变形；而当载荷仍然保持1800 N，应变继续增加达到(11.43±0.03)％时，涂层与316L不锈钢基材的结合界面彻底开裂失效，此时涂层内部同时具有横向裂纹和纵向裂纹，样品的抗弯强度约为(1.87±0.02) GPa。结论 超音速火焰技术制备出的NiCrWMoCuCBFe涂层具有良好的致密性及优异的力学性能。

Preparation and Mechanical Properties of NiCrWMoCuCBFe Coatings

The work aims to study the microstructure, composition and mechanical properties of NiCrWMoCuCBFe coating. The flowability and bulk density (apparent density) of the sprayed powder was characterized by Hall flowmeter. Then, NiCrWMoCuCBFe coating was prepared on 316L stainless steel substrate by High Velocity Oxygen Fuel (HVOF) spraying technique. The morphologies, microstructure and element compositions of the powder and the coating were investigated by SEM and EDS. The phases of the coating were characterized by XRD and Raman. Besides, the hardness, bonding strength and flexural strength of the coating were investigated by microhardness tester and universal material testing machine and then the fracture failure mechanism of the coating was analyzed. The NiCrWMoCuCBFe sprayed powder had great fluidity and was hardly oxidized in the process of spraying. The HVOF-sprayed NiCrWMoCuCBFe coating was very dense and exhibited typical lamellar structure. The coating was mainly composed of Ni-based solid solution and a small amount of NiO and Cr2O3 on the surface. In addition, the hardness of the coating cross section was approximately equal to that of surface which was about 600HV300g. The bonding strength between the coating and 316L stainless steel was larger than 70 MPa. When the load increased to 1800 N in the three-point bending test, the coating reached the strength limit with the strain about (4.81±0.3)%. Meanwhile, there was obvious plastic deformation. When the load remained unchanged, but the strain rose up to (11.43±0.03)%, the bonding interface between coating and 316L stainless steel substrate broke and failed. Thus, there were obvious transverse and longitudinal cracks inside the coating and the bending strength of the sample was about (1.87±0.02) GPa. HVOF-prepared NiCrWMoCuCBFe coating has excellent compactness and mechanical properties.