Al-Si-based nano-Si3N4 composite coating prepared by plasma spraying and laser remelting on magnesium alloy

作者：Wang Xin; Wang Wen Xian^*; Ge Ya Qiong; Cui Ze Qin; Xu Bing She

来源：Transactions of Materials and Heat Treatment, 2014, 35(2): 131-137.

• AZ31B magnesium alloys
• Elements distribution
• Energy dispersive spectrometers
• Excellent corrosion resistances
• Hardness and corrosion
• Laser re-melting
• Plasma spraying technology
• Solid solution strengthening

In order to improve the surface properties of magnesium alloy, the present study combined laser remelting with plasma spraying technology to fabricate Al-Si+1%nano-Si3N4 composite coating on AZ31B magnesium alloy substrate with a 5 kW continuous wave CO2 laser. The phase, microstructure, elements distribution of the remelted layer and bonded interface of the as-sprayed and laser remelted coatings were analyzed by scanning electron microscopy, energy dispersive spectrometer, X-ray diffraction. Hardness and corrosion resistance of the as-sprayed and remelted layer was examined with microhardness tester and electrochemical workstation. The results show that the interface bewteen composite coating and magnesium alloy substrate achieves a good metallurgical bonding after remelting. Under the role of laser remelting, the intermetallic compounds of AlN, Mg2Si precipitated in the remelted layer and the dispersed aluminum silicon solid solution strengthening phase effectively improve the hardness of the remelted coating. The maximum value of microhardness is 514 HV0.05, which is 10 times of that of the matrix. The excellent corrosion resistance of the remelted layer is due to the fine microstructure and the precipitation of corrosion-resistant strengthening phases, the self-corrosion current of the remelted layer reduces by one order of magnitude compared with that of as-sprayed layer and substrate.

• 出版日期2014
• 单位太原理工大学