硅莫砖的脆塑性变形特征与高角气固冲蚀机制的关联

Relations Between Brittle Plastic Deformation Features and Gas Solid Erosion Wear Mechanisms at High Impact Angle for Guimo Bricks

以硅莫砖为靶材,在25~1 200℃温度范围内进行弯曲应力–应变曲线测试和垂直气固冲蚀磨损试验,借助扫描电子显微镜观察靶材冲蚀后形貌,研究其脆塑性变形特征与高角冲蚀下的常温/高温气固冲蚀机制,并阐明两者的关联性。结果表明：硅莫砖冲蚀磨损率随冲蚀温度的增加而减小,1 200℃出现最小值0.95 mm^3/g;开始的塑性变形温度为800℃;在弹性变形阶段（25~800℃）,冲蚀磨损率与抗折强度成反比,主要冲蚀机制是冲击应力下骨料与基质的脆性断裂;在塑性变形阶段（800~1 200℃）,冲蚀磨损率与塑性应变量成反比,与弹性模量成正比,塑性变形逐渐成为主要冲蚀机制,是否伴随脆性断裂,由骨料和基质的临界断裂应力决定;本实验条件下800℃时主要冲蚀机制为微切削和基质断裂,1 200℃时仅为微切削。

The blending stress-strain curve test and vertical gas solid erosion wear test were carried out on guimo bricks at 25– 1 200 ℃, and the worn morphology of targets were examined by scanning electron microscopy to invesyigate the brittle plastic deformation features and high impact angle gas solid erosion wear mechanisms at room temperature and elevated temperature. The results show that the erosion wear rate of guimo brick decreases with the increase of erosion temperature and the minimum value is 0.95 mm^3/g at 1 200 ℃. The beginning plastic deformation temperature is 800 ℃. In the elastic deformation stage（at 25–800 ℃）, the erosion wear rate is inversely proportional to the blending strength, and the primary erosion mechanism is brittle fracture of aggregate and matrix under the role of impact stress. In the plastic deformation stage（at 800–1 200 ℃）, the erosion wear rate is inversely proportional to the plastic strain, while it is proportional to the modulus of elasticity. The plastic deformation gradually plays in a dominate role in the erosion process, and the critical fracture stress of aggregate and matrix determine whether the brittle fracture would accompany with the plastic deformation. In this work, the primary erosion mechanism is micro-cutting and fracture of matrix at 800 ℃, which is only micro-cutting at 1 200 ℃.