低碳钢表面激光熔覆层与热喷涂层组织与性能对比

Research on the Microstructure and Properties of Laser Cladding Layer and Thermal Spray Coating on the Surface of Soft Steel

利用CO2激光器在Q235低碳钢表面激光熔覆了Ni25合金涂层。用扫描电镜、显微硬度计对熔覆层的微观组织、显微硬度进行了测定与分析。结果表明:激光熔覆层质量良好,基本无裂纹、气孔等缺陷,覆层中存在着大量的树枝晶,与基体之间为冶金结合,结合强度高;而热喷涂层质量不好,存在明显的孔洞和间隙,与基体之间为机械结合,结合力微弱;经过激光重熔之后覆层的硬度明显高于喷涂层的硬度,且2种覆层的硬度均比基体的硬度要高。

Ni25 alloy coatings have been prepared by a CO2 laser on the soft steel （Q235）surface. Cross-section microstructure characteristics of the coating were studied by scanning electronic microscope and micro-hardness analysis. The results show that laser cladding layers, which have no defects of cracks and holes, contain a large number of dendrites. That is metallurgical bonding between the cladding layer and the substrate, which makes high bonding strength. But thermal spray coatings exist obvious holes and gaps. The combination is mechanical binding between the coating and the matrix. There is weak binding force. The average micro-hardness of laser cladding layer is higher than that of thermal spray coating, and the hardness of two coatings is much higher than that of the substrate.