Metal transfer and microstructure evolution during wire-feed deposition of TiB/Ti composite coating
Metal transfer and microstructure evolution during wire-feed deposition of TiB/Ti composite coating
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TiB/Ti 复合涂层送丝沉积过程中的金属转移和微观结构演变
DOI：
10.1016/j.jmatprotec.2019.116298
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发表时间：
2019-12-01
影响因子：
6.3
通讯作者：
Ma, Xinxin
中科院分区：
文献类型：
--
作者：
Bao, Yang;Huang, Lujun;Ma, Xinxin
采用新型Ti药芯焊丝，通过送丝气体钨极电弧熔覆原位合成两级TiB增强Ti复合涂层，提高Ti6Al4V合金的表面硬度和耐磨性。通过高速摄像机观察结合电弧电压分析来研究送丝沉积过程中的金属转移模式。结果表明，随着线电极距离增加2~6 mm，金属转移方式从间断桥接转移、渣柱转移转变为连续接触转移，同时工艺稳定性也随之提高。涂层中TiB的体积分数受金属转移方式的影响，可以排列为：渣柱转移>连续接触转移>间断桥接转移。显微组织分析表明，大部分TiB2颗粒在电弧区熔化，其余部分通过原位反应进行渣柱转移而充分溶解在熔池中，而另外两种模式均导致TiB2颗粒聚集在涂层中。因此，渣柱转移形成的涂层具有最大的硬度（571 HV0.5）和最小的磨损量（14.10 mg）。磨损形貌分析表明，TiB 的载荷剪切效应是涂层具有优异耐磨性的原因。本研究论证了通过丝基熔覆制备钛基复合涂层的可行性。
A new type of Ti flux-cored wire was used to in-situ synthesize two-scale TiB reinforced Ti composite coatings through wire-feed gas tungsten arc cladding, to enhance the surface hardness and wear resistance of Ti6Al4V alloy. Metal transfer modes during wire-feed deposition were investigated by high-speed camera observation in conjunction with arc voltage analysis. The results showed that the metal transfer modes varied from interrupted bridging transfer, slag column transfer, to continuous contact transfer with increasing the wire-electrode distance in 2-6 mm, accompanied by the improvement of process stability. The volume fraction of TiB in coating was governed by metal transfer modes, and can be arranged as: slag column transfer > continuous contact transfer > interrupted bridging transfer. Microstructure analysis revealed that most of TiB2 particles were melted in arc zone while the rest were fully dissolved among the weld pool through in-situ reaction for slag column transfer, while both other two modes caused the inclusion of TiB2 particle aggregations in coatings. Consequently, the coating formed by slag column transfer possessed the maximum hardness (571 HV0.5) and the minimum wear loss (14.10 mg). Worn morphologies analysis revealed that the load-shearing effect of TiB accounted for the superior wear resistance of the coating. This study demonstrates the feasibility of preparing titanium matrix composite coating through wire-based cladding.