AZ91D镁合金Ni-TiN-GO复合电沉积层组织性能

Microstructure and Properties of Ni-TiN-GO Composite Electrodeposition Layer on AZ91D Magnesium Alloy

摘要:

为提高AZ91D镁合金表面硬度、耐磨性及耐蚀性，采用纳米复合电沉积技术在AZ91D镁合金表面制备Ni-TiN-GO（氧化石墨烯）复合电沉积层，并对Ni-TiN-GO复合电沉积层真空退火，探究GO添加量及真空退火加热温度、保温时间对沉积层组织性能的影响。结果表明：添加0.1 g/L GO时，Ni²⁺沉积速率提高，沉积层均匀致密，Ni晶粒为(111)和(200)晶面双择优取向，沉积层硬度较基体提高10.79倍，摩擦系数为0.6，磨损方式主要为粘着磨损和轻微磨粒磨损，自腐蚀电流密度较基体下降3个数量级；当真空退火加热温度为350 ℃、保温时间为1 h时，沉积层表面均匀致密，性能最佳，硬度较未退火提高了1.15倍，摩擦系数降为0.4，磨损方式转为微弱磨粒磨损，自腐蚀电流密度下降2.34倍，耐铜绿假单胞菌微生物腐蚀性能提高。本研究将为促进AZ91D镁合金在装备轻量化领域及复杂工况下的广泛应用奠定基础。

Abstract:

To improve the surface hardness, wear resistance, and corrosion resistance of AZ91D magnesium alloy, a Ni-TiN-GO (graphene oxide) composite electrodeposition layer was prepared on the surface of AZ91D magnesium alloy using nano-composite electrodeposition technology. The Ni-TiN-GO composite electrodeposition layer was then subjected to vacuum annealing. The effects of GO addition amount, vacuum annealing temperature, and holding time on the microstructure and properties of the deposited layer were investigated. Results show that when the addition amount of GO is 0.1 g/L, the deposition rate of Ni²⁺ is increased, and the deposited layer exhibits a uniform and dense microstructure. The Ni grains in the deposited layer show a (111) and (200) preferred orientation. The hardness of the deposited layer is increased by 10.79 times compared to that of the substrate. The friction coefficient is 0.6, and the wear mechanism is mainly adhesive wear with slight abrasive wear. The self-corrosion current density of the deposited layer is decreased by 3 orders of magnitude compared to that of the substrate. When the vacuum annealing heating temperature is 350 ℃ and the holding time is 1 h, the surface of the deposited layer is uniform and dense, exhibiting the best performance. The hardness is increased by 1.15 times compared with that without annealing. The friction coefficient is reduced to 0.4, the wear mode is converted to weak abrasive wear. The self-corrosion current density is reduced by 2.34 times, and the resistance to Pseudomonas aeruginosa microbiologically influenced corrosion is improved. This study will lay the foundation for promoting the widespread application of AZ91D magnesium alloy in the field of equipment light massing and under complex working conditions.