T10钢低温双辉等离子表面渗镀铬硬化的研究

采用双辉等离子渗铬技术,首先在560℃对T10钢进行不同时间的渗铬,再对已渗铬试样进行4h离子氮化,研究了该工艺对渗镀铬层硬化效果的影响。结果表明:双辉渗铬后的渗层由厚3～5μm的沉积层+扩散层组成,沉积层组织致密并与基体结合良好,基体组织和晶粒度与渗铬前基本一致;沉积层铬浓度达45%(质量分数)以上,内有20～25μm的扩散层,铬浓度向内呈梯度分布;表面物相均由Fe,Fe-Cr,Cr7C3,Cr23C6等组成;渗层表面显微硬度达650～850HV,向内逐步降低,呈梯度分布。沉积层厚度、渗层深度、渗层的铬浓度及显微硬度等均随渗铬时间的增加而增加。渗层经离子氮化后的组织与氮化前的组织无明显变化,但表面物相为Fe-Cr,Cr7C3,Cr23C6,CrN,Fe4N,表面显微硬度提高到1000～1350HV,较未氮化前提高约60%以上。

碳素工具钢低温双辉等离子渗镀铬硬化的研究

利用双层辉光等离子渗金属技术,在580℃对T10钢进行表面渗镀铬硬化的研究。结果表明:渗镀层由沉积层+扩散层组成;沉积层厚5￣6μm,组织致密,与基体结合紧密,且w(Cr)>48%;内有15￣20μm的扩散层,扩散层中铬含量呈梯度分布;经X射线衍射分析,其表面物相由Fe、Fe-Cr、、Cr7C3、Cr23C6、等组成;渗层的显微硬度达700HV以上,硬度向内逐步降低,且呈梯度分布。

碳素工具钢560℃双辉等离子渗铬硬化的研究

采用离子氮化+双层辉光离子渗金属的复合处理渗铬新技术,对碳素工具钢进行560℃表面渗镀铬硬化研究。结果表明,渗镀层组织由沉积层+扩散层组成;渗镀层表面形成4～5μm的沉积层,含铬量达50%以上,致密并与基体冶金结合;内有20～25μm的扩散层,扩散层含铬量呈梯度分布;经X射线衍射分析,其表面物相由Fe-Cr、CrN、Cr7C3、Cr23C6等组成;渗镀层的显微硬度达1000 HV以上,硬度向内逐步降低,呈梯度分布。

Cyclic oxidation and hot corrosion of Al_2O_3 or Y_2O_3-dispersed low-temperature chromizing coating

Chromium coatings with and without Al_2O_3 or Y_2O_3 particles were prepared by chromizing the as-deposited Ni-film with and without Al_2O_3 or Y_2O_3 particles using a conventional pack-cementation method at 800 ℃. The cyclic oxidation at 800 ℃ and hot corrosion in molten 75% Na2SO4＋25% NaC1 at 800 ℃ of the three different chromizing coatings were investigated. The effects of Al_2O_3 or Y_2O_3 on the cyclic oxidation and hot corrosion behavior of the chromizing coatings were discussed. Microstructure results show that the codeposited Al_2O_3 or Y_2O_3 particles significantly retard the grain growth of the chromizing coating, which increases the cyclic oxidation and hot corrosion resistance of the chromizing coatings, due to the more rapid formation of purer and denser chromia scnle