激光熔覆Ni2Si／Ni3Si2金属硅化物合金涂层显微组织与耐蚀性

Microstructure and Corrosion Resistance of Laser Clad Coating of Ni2Si/Ni3Si2 Silicide Alloy

摘要:

以Ni76Si24（质量百分数）合金粉末为原料，利用激光熔覆技术在A3钢表面制得了组织由条件Ni2Si初生相及少量Ni2Si/Ni3Si2共晶组成的新型金属硅化物合金涂层，分析涂层显微组织并测定其在0．5mol/1 H2SO4水溶液及不同浓度NaCl水溶液中的阳极极化曲线，结果表明激光熔覆Ni2Si/Ni3Si2金属硅化物合金涂层表面平整，组织细小，与基体为完全冶金结合，同时由于涂层的组织组成相Ni3Si2本身均具有极好的耐蚀性并具有快速凝固细小均匀的显微组织，该激光熔覆Ni2Si/Ni3Si2金属硅化物合金涂层在0．5mol/l H2SO4及3．5％NaCl水溶液中均具有优良的耐蚀性能。

Abstract:

A corrosion resistant Ni2Si/Ni3Si2 silicide alloy coating was fabricated on a substrate of low carbon steel A3 by laser cladding of the Ni76Si24 alloy powders. The laser clad silicide alloy coating has a rapidly solidified homogeneous microstructure consisting of plate like Ni2Si primary phase and minor amount of Ni2Si/Ni3Si2 eutectics and is metallurgically bonded to the steel substrate. The corrosion resistances of the silicide alloy coating in the water solutions of 0.5mol/l H2SO4 and 3.5% NaCl were evaluated utilizing the electrochemical polarization corrosion test method. Because of the inherent excellent corrosion resisting properties of the constituting phases Ni2Si and Ni3Si2, and the rapidly solidified homogeneous microstructure, the laser clad Ni2Si/Ni3Si2 silicide alloy coating exhibits excellent corrosion resistance.