权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Development of High Strength and High Corrosion Resistant Mo Composite Material under Severe Environment

恶劣环境下高强高耐蚀钼复合材料的研制

基本信息

批准号：
11555187
负责人：
YOSHIO Tetuo
金额：
$ 8.77万
依托单位：
OKAYAMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B).
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

For pure Mo and Mo-0.5 mass% alloy nitrided at 1073K to 1373K in NH_3 gas, the microstructural observations of molybdenum nitride layer were carried out through an optical and a transmission electron microscope and X-ray diffraction analysis. Corrosion behavior of the nitrided specimens was also examined. A surface nitriding layer consisted mainly of two Mo nitrides : an outer one of γ-Mo_2N and an inner one of β-Mo_2N.A great number of{011}<011>-type micro-twins were observed in the β-Mo_2N layer whereas the microstructure of the γ-Mo_2N layer is almost free from lattice defects. The nitrided specimens exhibited excellent corrosion resistance even in 75wt% sulfuric acid solution at the boiling temperature of 460.8K compared with unnitrided specimens. Its corrosion rate decreased with decreasing nitriding time because of the suppression of cracking by decreasing thickness of the surface nitriding layer. The corrosion rate of the specimen nitrided at 1123K for 24h was less than 0.001mm/y in boiling 75% sulfuric acid. In a nitrided Mo-0.5Ti alloy an internal nitriding layer with remarkably high hardness of Hv〜800 was formed beneath the surface nitriding layer. The high hardness is considered to be ascribed from fine dispersion of extremely small titanium nitride particles in the Mo matrix. The hardness in the internal nitriding layer gradually decreased as the distance from the interface increased.

用光学显微镜、透射电镜和X射线衍射分析对纯Mo和Mo-0.5%（质量分数）合金在1073 ~ 1373 K的NH_3气氛中氮化后的氮化层进行了显微组织观察。对氮化试样的腐蚀行为进行了研究。表面氮化层主要由两种Mo氮化物组成，外层为γ-Mo_2N，内层为β-Mo_2N，β-Mo_2N层中存在大量{011}<011>型微孪晶，而γ-Mo_2N层的组织几乎没有晶格缺陷。氮化试样在沸腾温度为460.8K的75wt%硫酸溶液中也表现出优异的耐蚀性。随着渗氮时间的缩短，腐蚀速率降低，这是由于减少表面渗氮层的厚度抑制了裂纹的产生。经1123 K氮化24 h的试样在沸腾的75%硫酸中的腐蚀速率小于0.001mm/y。Mo-0.5Ti合金经渗氮后，在表面渗氮层下形成了硬度高达Hv ≥ 800的内渗氮层。高硬度被认为是由于非常小的氮化钛颗粒在Mo基体中的精细分散。随着离界面距离的增加，内渗层硬度逐渐降低。