扫描速度对激光熔覆Al-Ni-TiC-CeO_2复合涂层组织与性能的影响

Effect of Scanning Speed on Microstructures and Properties of Laser Cladding Al-Ni-TiC-CeO_2 Composite Coatings

目的解决S355海洋钢在海洋环境中的腐蚀、磨损问题,制备良好的涂层结构,并延长其使用寿命。方法采用激光熔覆工艺在S355海洋钢表面制备Al-Ni-Ti C-CeO_2复合涂层,研究扫描速度对涂层组织与性能的影响,利用扫描电镜观察涂层的微观组织形貌,结合X射线衍射仪对涂层物相进行分析。采用显微硬度计、摩擦磨损试验机和电化学工作站对涂层的硬度、耐磨性和耐蚀性进行测试分析。结果不同扫描速度制备的涂层均出现Al-Fe相,涂层与基体有良好的冶金结合。随着扫描速度的增加,涂层厚度逐渐降低,涂层内组织由短棒状向颗粒状转变,裂纹和气孔逐渐减少,稀释率逐渐降低。涂层表面硬度最高为846.6 HV0.2。涂层磨痕宽度最低为449.4μm,深度为15.5μm,磨损速率最低为3.88×10^(–6)mm^3/(N·s)。涂层自腐蚀电位最大为–0.60396V,最小自腐蚀电流密度为2.3753×10^(–8)A/cm^2,阻抗最大能达到2.5kΩ,腐蚀速率最低为0.0725mm/a,约为基材的33.6%。结论在S355海洋钢表面激光熔覆Al-Ni-TiC-CeO_2复合涂层,可有效提高其耐磨与耐蚀性能。当扫描速度为7.5 mm/s时,性能最佳。

The work aims to solve the corrosion and wear of S355 offshore steel caused by the marine environment and prepare excellent coating structure to prolong the service life. Al-Ni-TiC-CeO2 composite coatings was prepared on S355 offshore steel by laser cladding technique and the effect of scanning speed on the microstructure and properties of the coating was studied. Microstructure morphology of coatings was observed with scanning electron microscope and phase of the coatings was analyzed by X-ray diffractometer. The hardness, wear resistance and corrosion resistance of coating were tested and analyzed by micro-hardness tester, friction and wear test machine and electrochemical workstation. The Al-Fe phase appeared in the coatings prepared by different scanning speeds and the coating showed a good metallurgical bonding with the substrate. With the increase of the scanning speed, the thickness of the coating gradually decreased. The microstructure of the coating was transformed from a short rod-like structure to granular structure. The pores, cracks and coating dilution rate gradually decreased. The surface hardness of the coating reached the maximum value of 846.6 HV0.2. The minimum wear width and wear depth was 449.4 and15.5 μm, respectively. The wear rate was reduced to a minimum of 3.88×10–6mm3/(N·s). The maximum corrosion potential of the coating was –0.603 96 V, the minimum corrosion current density was 2.3753×10–8A/cm2, the maximum impedance can reached 2.5 kΩ, and the minimum corrosion rate of the coating was 0.0725 mm/a, which was about 33.6 percent that of the substrate. Al-Ni-TiC-CeO2 coatings on S355 offshore steel by laser cladding can effectively improve wear resistance and corrosion resistance of the coatings. When the scanning speed reaches 7.5 mm/s, the performance of the coating is the best.