TA2钛合金表面激光熔覆金属钽探索实验研究

Exploration Experimental Research on Laser Cladding of Ta Coat on TA2 Titanium Alloy Surface

在保证钛合金穿地阀门硬密封面耐腐蚀性前提下,为了提高其硬度、耐磨性及抗压疲劳性能,以TA2钛合金板材作为基体,利用YAG激光器进行表面激光熔覆纯钽(Ta)的探索实验研究。分别采用OM、SEM、EDS及显微硬度计,研究了激光熔覆的Ta涂层的冶金结合情况、组织结构、成分分布及硬度分布。结果表明:在TA2钛合金表面直接激光熔覆纯Ta粉是可行的,且制备的Ti-Ta合金涂层与基体形成良好的冶金结合;激光熔覆层内Ti元素稀释度较大,随着与结合面距离的增加,稀释度逐渐减小;激光熔覆层与基体结合区主要由枝晶组成,熔覆层中部由枝晶及部分块状组织组成;熔覆层显微硬度HV_(0.2)为190~200,相对Ti基体硬度提高了40以上,而结合区显微硬度HV_(0.2)为200~220,硬度梯度变化较为明显。

In order to ensure the corrosion resistance of the hard seal surface of titanium alloy earth-penetration valve, and improve the hardness, wear resistance and compressive fatigue properties of the valve, laser cladding of pure tantalum was carried out on the surface of TA2 titanium alloy by YAG laser. The metallurgical binding degree, microstructure, component and hardness distribution of layer-cladding Ta coat were analyzed by OM, SEM, EDS and microhardness tester. The results indicate that direct laser cladding of pure Ta powder on TA2 titanium alloy surface is feasible, and there is well metallurgical binding between Ti-Ta alloy coat and the substrate. The dilution of Ti element in laser cladding layer is large,and the dilution decreases with increased distance away from the binding surface. The binding region of laser cladding layer and the substrate is composed mainly of dendrites, and the middle region in the cladding layer is composed of dendrites and partial massive microstructure. The microhardness HV0.2 of the cladding layer is 190- 200, more than 40 higher than that of Ti substrate. The microhardness HV0.2 of the binding region is 200- 220 ,and therefore the hardness gradient is relatively obvious.