我国压铸模具钢研究新进展

介绍了我国压铸模具钢材料研究和应用新进展。通过研究合金元素对压铸模具材料性能影响,开发出低Si、V及含Ni、Co、W等新型压铸模具钢;通过降低钢中S含量、采用RE改变夹杂形态和优化锻造工艺,模具钢等向性能达到90%以上;比较常规电渣重熔、气保电渣重熔和真空自耗三种工艺生产的压铸材料,钢中N含量分别为150×10^(-6)、90×10^(-6)和≤40×10^(-6),O含量分别为24×10^(-6)、15×10^(-6)和6×10^(-6);利用ASPEX Explorer型金属质量分析仪对三种工艺夹杂物指数统计分析,采用真空自耗冶炼的非金属夹杂物数量呈指数减少,并且没有>5μm的非金属夹杂物,模具冲击性能大幅提升,7 mm×10 mm无缺口冲击功可达到450 J;制定了高端压铸模具材料显微组织、无缺口冲击评价指标和规范;随着一体化压铸技术发展,未来模具材料向着大型化、超洁净、高精度和长寿命方向发展。

电液控制器用加Bi-Ce易切削不锈钢1.4104的开发

大冶特钢公司电液控制器用高端不锈钢1.4104(/%:0.16C,1.23Mn,16.40Cr,0.41Ni,0.43Mo,0.023Ca)采用20 t电弧炉初炼、LF与VD精炼,铸1.2 t锭,径锻成材工艺生产,通过喂入Bi包芯线(Bi:0.036%)与稀土球化剂(Ce:0.054%)后该钢横向力学性能与切削性能大幅提高。与无Bi-Ce钢相比,含Bi-Ce钢夹杂物总量减少84.4%,MnS夹杂减少85.5%,夹杂物平均尺寸由4.5μm增至13.7μm,切削力平均降低70~80 N,切屑更厚,更加易断,横向断面收缩率由3%提高至17%。

Parylene film for sidewall passivation in SCREAM process

Trench sidewall passivation is a key step in the SCREAM (single crystal reactive etching and metallization) process for releasing suspended MEMS structures. In this paper, the parylene thin film is reported to serve as the passivation layer owing to its excellent conformality, chemical inertness, mechanical performance, and especially, low growth temperature. The deposited parylene films are characterized and the test structures are released through SCREAM process utilizing the parylene films as a passivation layer. The results show that as a passivation layer the parylene has more merits than the PECVD SiO2 film.