锆合金表面Cr涂层在高温压缩下的界面开裂行为EI北大核心CSCD

在事故条件下核反应堆的核心部件镀Cr锆合金包壳管容易受到挤压发生变形,导致Cr涂层产生裂纹影响涂层的保护性能,因此研究镀Cr锆合金在高温压缩下的裂纹扩展行为十分有必要。采用环向压缩试验研究不同厚度Cr涂层锆合金在不同温度下的开裂行为,通过扫描电子显微镜(SEM)、X射线衍射仪(XRD)和维氏硬度计等测试设备研究不同压缩试验温度下的镀Cr锆合金包壳管表截面裂纹微观形貌,并统计表截面裂纹密度及截面裂纹最大宽度。分析包壳材料的载荷-位移曲线和裂纹扩展行为,评价温度和涂层厚度对镀Cr锆合金包壳管力学性能的影响。研究结果表明:镀Cr锆合金包壳管在高温工况下,抗压强度会下降,断裂韧性增加;当涂层厚度增加时,表截面裂纹密度减少,裂纹张开尺寸增大;裂纹首先在表面产生,然后逐渐向基体扩展,并随着变形量的增加逐渐向基体扩展,最终在膜基结合处停止;试样变形量从10%压缩到50%时,截面裂纹的新增主要来自表面主裂纹分叉,且在压缩过程中Cr涂层并不会剥落,Cr涂层与锆基体结合性能良好。研究不同厚度锆合金Cr涂层包壳管在高温压缩下的膜基界面裂纹的扩展行为,可为锆合金包壳管的涂层制备提供数据支持。

Interface Cracking Behavior of Cr Coating on Zirconium Alloy under High Temperature Compression

Under accident conditions, the Cr-Zr alloy cladding tube, the core component of nuclear reactor, is prone to extrusion deformation, resulting in cracks in the Cr coating and affecting the protective performance of the coating. Therefore, it is necessary to study the crack propagation behavior of Cr-coated zirconium alloy under high temperature compression. The circumferential compression test is used to study the cracking behavior of Cr-coated zirconium alloy with different thicknesses at different temperatures. Scanning electron microscopy (SEM), X-ray diffraction (XRD) and Vickers hardness tester are used to study the micro-morphology of cross-sectional cracks on the surface of Cr-coated zirconium alloy cladding tubes at different compression test temperatures. The density and maximum width of cross-sectional cracks are counted. The load-displacement curve and crack propagation behavior of the cladding material are analyzed to evaluate the effects of temperature and coating thickness on the mechanical properties of Cr-Zr alloy cladding tube. The results show that under high temperature conditions, the compressive strength of Cr-coated zirconium alloy cladding tube decreases and the fracture toughness increases; when the coating thickness and temperature increase, the crack density of surface section decreases and the crack opening size increases; cracks first appear on the surface and then gradually expand to the matrix, and gradually expand to the matrix with the increase of deformation, and finally stop at the die-base junction; when the deformation of the specimen is compressed from 10% to 50%, the increase of the cross-section cracks is mainly due to the bifurcation of the surface main cracks, and the Cr coating does not peel off during the compression process. The Cr coating has good bonding performance with the zirconium substrate. The propagation behavior of interfacial cracks at the film-substrate interface of zirconium alloy Cr-coated cladding tubes with different thicknesses under high temperature compression is studied, which provides certain data support for the coating preparation of zirconium alloy cladding tubes.