氩弧熔覆原位自生TiN-TiB_2/Ni涂层组织表征及反应机制（英文）

Microstructure and Formation Mechanism of in-Situ TiN-TiB_2/Ni Coating by Argon Arc Cladding

采用氩弧熔覆技术,选择不同的BN/Ti摩尔比,在35CrMnSi钢表面原位合成了TiN-TiB_2增强Ni基涂层;利用XRD、SEM和TEM等方法分析了涂层的显微组织和结构特征。结果表明,在BN/Ti摩尔比大于0.33时,熔覆组织主要由TiN,TiB_2,TiB,Cr_(23)C_6和γ-Ni组成;随着BN/Ti摩尔比的增加,针状TiB逐渐消失而棒状TiB_2颗粒增多,且颗粒均匀细小;通过计算表明在试验温度下熔覆层中增强相的形核驱动力由大到小依次顺序为TiN-TiB_2-TiB;探讨了Ti-BN-Ni体系中增强相的形成机制,当BN/Ti摩尔比为0.67时,熔覆层具有较高的平均硬度及优良的干滑动磨损性能。

An in situ synthesis method was developed to produce a Ni alloy composite coating reinforced by in situ reacted TiN and TiB2 particles using argon arc cladding （AAC） with different molar ratios of BN/Ti on a 35CrMnSi steel substrate. The microstructures of the clad coatings were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. Results show that the phases of the coating are TiN, TiB2, TiB, Cr23C6 and y-Ni. As the BN/Ti ratio increases, the needle-like TiB phase almost disappears and the number of rod-like TiB2 particles increases. Their shape become smaller. The computed results show that the nucleation driving force of the major reinforcing phases from low to high is TiN-TiB2-TiB at different test temperatures. Moreover, the growth mechanism of the phases was discussed in the Ti-BN-Ni system. When the BN/Ti molar ratio is 0.67 the clad coating shows the highest average micro-hardness and excellent wear resistance at room temperature under normal atmosphere conditions.