复合涂层结构的影响
(1． 华中科技大学 模具技术国家重点实验室，武汉 430074;
2． 武汉理工大学 材料科学与工程学院，武汉 430070;
3． 武汉理工大学 材料复合新技术国家重点实验室，
武汉 430070)
摘 要: 将自蔓延高温合成（SHS）技术与铸造工艺结合起来， 制备了铸造钢基表面TiC-Fe梯度复合材料, 研究了钢液的浇注温度、 Ti-C-Fe预制块的组成及其相对密实度等工艺参数对梯度复合涂层结构的影响。 结果表明： 在保证预制块能被浇注的钢液直接点燃的条件下，适当提高钢液的浇注温度、 降低预制块的密实度均有利于梯度复合涂层的形成； 而且在预制块中掺加适量的低熔点金属稀释剂不仅可降低合成TiC颗粒的尺寸， 而且也有利于梯度复合涂层的形成。 梯度复合涂层的形成与钢液向预制块中的渗透、 预制块中Fe和低熔点稀释剂的熔化以及合成的TiC颗粒向钢液中的扩散等作用有关。
关键字: 铸造； 自蔓延高温合成； TiC-Fe涂层；梯度复合； 工艺参数
（1. State Key Lab of Die & Mould Technology, Huazhong University of Science and Technology, Wuhan 430074, China;
2. School of Materials Science and Engineering, Wuhan University of Technology, Wuhan 430070, China;
3. State Key Lab of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology,Wuhan 430070, China）
Abstract:A TiC-Fe cermet graded composite coating on a cast steel substrate was successfully fabricated by an SHS casting route. The effects of technological parameters, such as pouring temperature of liquid steel, composition of Ti-C-Fe preform and its relative green density, on the microstructure of the coating were emphatically studied. The results show that, under the condition of ensuring the preform to be ignited, properly increasing the pouring temperature of liquid steel and decreasing the green density of the preform are favorable to the formation of the graded composite coating. Furthermore, adding a kind of metal diluents with lower melting point into the preform not only can decrease the size of the synthesized TiC particles, but also is more advantageous for the formation of the graded composite coating. It is considered by analysis that the formation of the graded composite coating is related to the combined effects of the infiltration of the melt into the preform, the fusion of Fe powders and the diluents in the preform, and the converse diffusion of the synthesized TiC particles into the poured melt.
Key words: SHS; TiC-Fe cermet coating; graded composite; technological parameter
