20钢表面Cr-Al共渗工艺研究

Technique of Co-permeation of Chromium and Aluminum at Surface of 20 Steel

采用固体粉末法对20钢在不同渗剂配方、不同热处理条件下Cr-Al共渗,利用金相显微镜、X射线衍射仪,对Cr-Al共渗试样渗层的组织和物相进行了分析,并对渗剂成分及配比对渗层的影响做了研究,对在950℃,1 000℃和1 050℃所得渗层的组织和性能方面进行了对比。结果表明:经Cr-Al共渗后的20钢,随温度的提高,共渗速度与渗层厚度均提高。渗层主要由黑色层Al8Cr5和白亮层AlFe3两部分组成,其渗层弥散分布黑色颗粒SiC。最终得出最佳工艺参数:共渗温度1 050℃;共渗时间5h;渗剂配方Cr2O310g,Al 5g,Al2O315g,SiC 15g,NaF 1.5g。

Cr-Al co cementation on 20 steel was done by the way of solid powder in different permeability agent formula, different heat treatment condition. The organizations and images of the Cr-Al co cementation layer were analyzed, using optical microscope, X ray diffraction equipment. The organization and performance of carbonitriding layer were compared at 950 ℃, 1 000℃ and 1 050℃. The experimental results show that by the Cr-Al co-cementation, with the increase of temperature, layer thickness and the speed of co-cementation are improved all together. The layer was composed of two parts were black layer A18 Cr5 and white layer AlFe3, and the granular black SiC were distributed in the layer. Eventually the best process parameters were obtained： he Cr-Al co cementation temperature 1 050℃ ; The Cr-Al co-cementation time 5h; Dialysis dose prescription was composed of Cr2O3 10 g, Al5 g , Al2O3 15 g, SiC 15 g, NaF 1.5 g.