碳化铬金属陶瓷熔覆层的组织及性能研究

Investigation of Strueture and Property of SHSDeposit.or Chromium Carbide Cermet

利用自蔓延高温合成（ＳＨＳ）熔铸技术将碳化铬的高温熔体铺展在平面样品的钢表面上，从而形成厚度为几毫米的熔覆层。为克服碳化铬与底材的润湿问题，采用与Ｆｅ有良好互溶性的Ｃｒ作为润湿功能层。在此基础上，使Ｃｒ－Ｃ合金层中的碳作阶梯改变，从而获得了梯度熔覆层结构，采用氮气加压（１００ＭＰａ）和预热工艺（３００℃）等措施，控制反应燃烧温度，改善熔体流动性，增大熔渣分离速度，有利于提高熔覆层表面平滑程度。以９５０℃盐水循环激冷实验评价熔覆层与底材结合强度。结果表明，循环次数大于４０次时仍未出现剥落迹象。研究认为，良好的结合强度来源于界面间强烈的治金作用以及梯度成分分布。

A depsition layer with thickness of a few millimeters is formed by using selfpropagation high temperature synthesis (SHS) in order to spread the melted chromium car-bide with high temperature onto the surface of plane steel substrate. In order to improvewetting capacity of chromium carbide with the substrate, Cr is employed as a wetting func-tional eomponent due to its fine dissolubility with Fe and,by doing so,the content of carbonin the alloy of Cr-C changes stepwise so that a gradient composition ablation is obtained.Employing pressured N_2 (10 MPa) and preheating process (300℃) for controlling reactiontemperature, improving the flowability of the melt,and increasing separation rate of theslag ,the smoothness of deposit surface may be improved. Repeated thermal quenching withbrine of 950℃ is carried out onto the deposit to evaluate its kinetic adhesion with the sub-strate and it is shown that there is no signs of peeling even after more than 40 cycles. It ispointed out by the investigation that a fine bond strength comes from intense metallurgicalinteraction and gradient composition at the ablation root.