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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 improve the hardness, wear resistance and compressive fatigue resistance of the titanium alloy wear-resistant valve sealing surface, TA2 titanium alloy plate was used as the substrate, and the laser cladding of pure tantalum (Ta ) To explore the experimental study. The metallurgical bonding, microstructure, composition distribution and hardness distribution of laser clad Ta coating were investigated by OM, SEM, EDS and microhardness tester respectively. The results show that it is feasible to laser cladding pure Ta powder on the surface of TA2 titanium alloy, and the prepared Ti-Ta alloy coating forms a good metallurgical bond with the matrix. The Ti element dilution in the laser cladding layer is larger, With the increase of the distance from the bonding surface, the dilution gradually decreases. The bond zone between the laser cladding layer and the substrate mainly consists of dendrites, and the middle part of the cladding layer consists of dendrites and some massive structures. The microhardness HV 0.2 of the cladding layer is From 190 to 200, the hardness of Ti matrix increased by more than 40, while the hardness of junction area HV_ (0.2) was 200 ~ 220, the hardness gradient changed obviously.