Study on microstructure and thermal shock resistance of plasma sprayed Cr₂O₃/8YSZ composite coating

等离子喷涂Cr₂O₃/8YSZ复合涂层微观组织及抗热冲击性能研究

National Cold Rolled Strip Equipment and Process Engineering Technology Research Center, Yanshan University, Qinhuangdao 066004, China

Received: 19 June 2023

Abstract

In order to explore the high temperature performance of Cr₂O₃/8YSZ composite coating, four kinds of Cr₂O₃/8YSZ composite coatings were prepared on the surface of Q235 steel by using the plasma spraying technology (the content of 8YSZ is 50%, 30%, 20% and 0%, respectively). The morphology of the coating was characterized through thermal field emission scanning electron microscopy, and the distribution of elements in the section of the coating was scanned by using EDS line. The phase composition of the composite coating was analyzed by using X-ray diffractometer, and the surface roughness of the composite coating was measured by using surface profilometer. The microhardness of the coating was measured by using automatic micro-Vickers hardness tester, and the scratch resistance of the coating was compared by using scratch tester. The thermal shock resistance of the coating was tested in Gleeble-3800 thermal physical simulator, and the cross section morphology after thermal shock was observed and analyzed. The results show that when the ratio of Cr₂O₃ to 8YSZ is 7∶3, the sample coating has good thermal shock resistance due to the deflection effect of 8YSZ on the vertical cracks and the thermal stress release effect of the pores and cracks in the coating.

摘要

为了探究Cr₂O₃/8YSZ复合涂层高温性能, 利用等离子喷涂技术在Q235钢表面制备了4种不同混合比例的Cr₂O₃/8YSZ复合涂层(8YSZ含量分别为50%, 30%, 20%, 0%)。通过热场发射扫描电镜对涂层的形貌进行SEM表征并对涂层的截面元素分布进行EDS线扫, 采用X射线衍射仪分析复合涂层的物相组成, 利用表面轮廓仪测量了复合涂层的表面粗糙度, 使用全自动显微维氏硬度计对涂层的显微硬度进行测量, 采用划痕仪对涂层的抗划伤性能进行对比, 利用Gleeble-3800热物理实验模拟机对涂层的抗热冲击性能进行测试, 并对热冲击之后的截面形貌进行观察分析。结果表明, 当Cr₂O₃与8YSZ比例为7∶3时, 由于8YSZ对垂直裂纹的偏转作用以及涂层内部存在的孔隙和裂纹对热应力的释放作用, 该样本涂层具有较好的抗热冲击性能。