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运用等离子离心熔覆技术在钢管内壁成功制备厚度约为2 mm铁基梯度涂层,采用该方法制备的涂层结构致密、无气孔和裂纹。采用扫描电镜、X射线衍射仪和电子探针对熔覆层的显微组织、物相、成分分布进行表征和分析;并对该梯度涂层的硬度分布和耐磨性能进行检测。结果表明:离心熔覆时熔池中的Fe、W、Mo元素在离心力作用下发生径向迁移而导致熔覆层形成梯度显微组织,沿熔覆层由里及表由亚共晶向共晶和过共晶过渡;大量碳化物(M23C6、M7C3和M6C)在表层的生成保证了该区域的硬度和耐磨性,梯度熔覆层表层的显微硬度为基体的7.5倍,熔覆层摩擦系数和磨损量分别为GCr15的88%和21%。
The centrifugal gravition technique was used to successfully prepare the iron-based gradient coating with a thickness of about 2 mm on the inner wall of the steel tube. The coating prepared by this method has compact structure, no pores and cracks. The microstructure, phase and composition distribution of the coating were characterized and analyzed by scanning electron microscopy, X-ray diffraction and electron probe. The hardness distribution and wear resistance of the coating were tested. The results show that the radial migration of Fe, W and Mo in the molten pool occurs due to the centrifugal force, resulting in the formation of gradient microstructure of the cladding layer. Crystal and hypereutectic transition; the formation of a large number of carbides (M23C6, M7C3 and M6C) in the surface layer to ensure the hardness and wear resistance of the region, the microhardness of the gradient cladding layer surface is 7.5 times the matrix, the cladding layer The coefficient of friction and wear are 88% and 21%, respectively, of GCr15.