Cuilan WU
,
Chengping LUO
,
Ganfeng ZOU
材料科学技术（英文）
Low temperature composite chromizing is a process composed of a plain ion-carbonitriding or ion-nitriding at 550~580℃, followed by a low-temperature chromizing in a salt-bath of 590℃. The microstructure and properties of the low temperature composite chromized layer on H13 tool steel were investigated using metallography, X-ray diffraction, microanalysis, hardness and wear tests. It was found that this low temperature process was thermodynamically and kinetically possible, and the composite chromized layer on H13 steel, with a thickness of 3~6 μm, consisted of three sub-layers (bands), viz. the outer Cr-rich one, the intermediate (black) one, and the inner, original white layer. After chromizing, the former diffusion layer was thickened. The results of X-ray diffraction showed that the composite chromized layer contained such nitrides and carbides of chromium as CrN, Cr2N, (Cr, Fe)23C6, and (Cr, Fe)7C3, as well as plain α-(Fe, Cr). A high surface microhardness of 1450~1550 HV0.025, which is much higher than that obtained by the conventional ion carbonitriding and ion nitriding, was obtained. In addition, an excellent wear resistance was gained on the composite chromized layer.
关键词:
H13 tool steel
,
null
,
null
陈高飞
,
公茂琼
,
邹鑫
,
吴剑峰
,
汪胜
工程热物理学报
对乙烷、丙烷纯质及三种不同浓度比例的乙烷／丙烷二元混合物在内径为8mm的水平管内进行了饱和流动沸腾传热特性的实验研究，重点分析了热流密度、质量流量的变化对二元混合工质传热系数的影响。选用了4种专用于计算混合物流动换热的关联式，并与实验数据进行了比较，其中Gungor—Winterton and Thome关联式和Zou关联式的预测偏差相对较小，且计算过程较为简单，较适合用于该工况范围的混合工质传热预测。
关键词:
流动沸腾
,
乙烷
,
丙烷
,
传热关联式
,
水平管
