真空等离子喷涂钨涂层组织与热行为研究（英文）

Thermal Performance and Microstructure of Vacuum Plasma Sprayed Tungsten Coatings under Cyclic Heat Load

采用真空等离子喷涂技术在铜基体表面制备了钨涂层,分别通过NiCrAl和W75Cu25涂层作为中间层。5 MW/m2,2 s的高热负荷电子束实验表明NiCrAl中间层提高了涂层的热导率并降低了热应力和残余应力值。W75Cu25涂层作为中间层则表现出较差的热疲劳性能。高热负荷电子束真空等离子喷涂钨涂层表现出侵蚀和微裂纹。因热应力导致涂层发生塑性变形,在高温情况下裂纹起源于熔融的钨颗粒,但是,裂纹被钨涂层塑性变形和孔洞所抑制。

Tungsten coatings on copper substrate were prepared by vacuum plasma spraying（VPS）. Ni Cr Al and W75Cu25 materials were selected as intermediate layers. The experiment result of cyclic heat load of electron beam with 5 MW/M2（heat flux） and 2 s pulse duration indicates that Ni Cr Al interlayer improves the thermal conduction of the coatings and reduces their thermal and residual stress. The specimen with W75Cu25 interlayer fails with a bad thermal performance because of fabrication problems. The microstructure characterization of the VPS-W coating shows that erosion crater and fine microcracks appear on the tungsten coating after cyclic heat load tests. And erosion crater has a coarse and loose microstructure. Local plastic deformation occurs in the coating because of thermal stress. Cracks originate from debonding of molten tungsten particles at high temperature. However, the crack propagation is constrained by local plastic deformation and pores in the tungsten coating.