【摘要】 对涂层结构断裂机理的研究是保证高厚度热喷涂涂层安全和稳定的关键。在Q235钢表面高速电弧喷涂不同厚度的铝涂层。对涂层试样进行三点弯曲试验,考察了涂层在受拉、受压及同时受拉力和压力情况下的力学性能,通过扫描电镜观察试样的断裂行为,并通过梁弯曲理论单面、双面涂层2种方法计算了涂层的弹性模量。结果表明:当涂层厚度小于800μm时,涂层/基体结构弯曲强度好于基材;随着弯曲应变的增加,裂纹开始出现在涂层表面并逐渐沿着涂层厚度方向进行扩展,到达涂层内部靠近界面的位置,裂纹沿着试样长度方向向两侧不断扩展,最终涂层脱落;梁弯曲法单、双面法计算得到的涂层弹性模量相近,但与基材相差较大,这主要受涂层自身结构影响。更多还原

【Abstract】 Aluminum coatings with various thickness on Q235 steel substrate were prepared by high velocity arc spray(HVAS) technique.Three-point bending test was tested to study the mechanical properties of coatings under three kinds of stresses(tensile stress,compressional stress,tensile & compressional stress). In addition,the fracture behavior of aluminum coatings was examined by scanning electron microscopy,and then the elasticity modulus of the coatings was calculated by beam bending theory with single side model or double side model. Results showed that when the thickness of coating was less than 800 μm,the bending strength of coating/substrate behaved better than that of substrate. As the bending strain increased,the cracks initially appeared on the surface of coating and then extended along the direction of the coating thickness to the interface of coating/substrate. Furthermore,the cracks extended to both sides of the sample length direction and the coating was finally peeled off. The elasticity modulus of coating calculated by beam bending theory with single side model and double side model was similar,but presented large difference with that of substrate,which mainly resulted from the structure of coating.更多还原