C.G. Zhou
,
H.B. Xu and S.K. Gong (Department of Materials Science and Engineering
,
Beijing University of Aeronautics and Astronautics
,
Beijing 100083
,
China) K. Y. Kim (Department of Materials Science and Engineering
,
Pohang University of Science and Technology
,
San31
,
Hyoja-dong
,
Pohang 790-784 Korea)
金属学报(英文版)
The halide-activated pack cementation method is utilized to deposit aluminide coat- ings on TiAl alloys. Emphasis is placed on the effect of alloying elements on the aluminizing behavior of TiAl alloy. The addition of a small amount of Nb or Cr in the TiAl improves significantly the aluminizing kinetics of TiAl alloys by increasing the solid-state division of Al through the formation of stable TiAl3 layer. The TiAl3 layer formed on the TiAl alloyed with Nb or Cr has better toughness than the TiAl3 formed on the non-alloyed TiAl. The reason for better toughness of the coating formed on TiAl is that partial TiAl3 with tetragonal structure was changed to high symmetry cubic L12 structure since Nb or Cr was dissolved into TiAl3. The TiAl3 layer formed on the TiAl alloyed with Nb or Cr has much better oxidation resistance than the TiAl3 layer formed on the non-alloyed TiAl. It is attributed to change in the crystal structure of TiAl3 from the brittle tetragonal DO22 to the ductile cubic L12 by addition of small amount of Nb or Cr.
关键词:
TiAl
,
null
,
null
,
null
Chinese Physics Letters
The quantitative analysis of zinc isopropyl-isooctyl-dithiophosphate (T204) mixed with lube base oil from Korea with viscosity index 70 (T204-Korea70) is presented by using terahertz time-domain spectroscopy (THz-TDS). Compared with the middle-infrared spectra of zinc n-butyl-isooctyl-dithiophosphate (T202) and T204, THz spectra of T202 and T204 show the weak broad absorption bands. Then, the absorption coefficients of the T204-Korea70 system follow Beer's law at the concentration from 0.124 to 4.024%. The experimental absorption spectra of T204-Korea70 agree with the calculated ones based on the standard absorption coefficients of T204 and Korea70. The quantitative analysis enables a strategy to monitor the formulation of lubricating oil in real time.
关键词:
infrared-spectroscopy;dielectric-properties;zddp;water
詹茂盛
,
方义
,
王瑛
,
范荣峥
航空材料学报
doi:10.3969/j.issn.1005-5053.2000.04.010
在40℃和80℃环境中,分别对Bayer-PC、Japan-PC、Korea-PC三种聚碳酸酯缺口冲击试样进行了热空气老化和热水老化实验研究.在0～400h老化时间内,研究了这三种PC的热空气老化和热水老化对冲击强度和断面形貌的影响,讨论了PC热空气老化和热水老化机理.结果表明:老化前,Japan-PC、Korea-PC和Bayer-PC冲击强度分别为95kJ/m2、83 kJ/m2和55 kJ/m2;在40℃和80℃热空气老化后,三种PC冲击强度均有所下降,其中80℃热空气老化引起的降幅最大,热空气老化400h后的冲击强度顺序为Japan-PC>Korea-PC>Bayer-PC,在40℃热水老化后,三种PC的冲击强度几乎不受老化时间影响;在80℃热水老化后,三种PC冲击强度均有所下降,其中Bayer-PC降幅最小,Japan-PC次之,Korea-PC最大,但PC的平衡冲击强度大小与热空气老化的情况相同.由扫描电镜对冲击断面形貌观察可知,未老化的三种PC均以剪切屈服破坏机理为主,老化后的三种PC主要以银纹集中破坏机理为主.
关键词:
聚碳酸酯
,
热空气老化
,
热水老化
,
破坏形貌
李兴无
,
沙爱学
,
储俊鹏
,
张雷
,
路民旭
材料工程
doi:10.3969/j.issn.1001-4381.2007.09.001
通过测试不同淬火温度下的拉伸应力应变曲线、750～790℃淬火拉伸断裂后均匀变形区域的X射线衍射谱研究了淬火温度对Ti-3Al-4.5V-5Mo钛合金形变诱发马氏体的影响.结果表明:该合金在750～790℃淬火后拉伸变形机制为亚稳定β相变形诱发马氏体转变,790℃淬火合金在6.5%的变形量下亚稳定β相基本完全转变为α″马氏体.790℃淬火后拉伸形成应力诱发马氏体,β立方→α″σ;750℃淬火后拉伸形成应变诱发马氏体,β立方→β正方→α″ε.形变诱发α″相在拉伸变形时发生晶格重新取向:[010] α″方向平行于拉伸轴线,[100]α″方向垂直于拉伸轴线.
关键词:
Ti-3Al-4.5V-5Mo
,
形变诱发马氏体
,
α″相
钱善华
,
胡含
,
刘科言
,
李庆忠
材料保护
目前,对液晶材料与蓖麻油混合后的润滑性能研究不多.在四球试验机上开展齿轮油、蓖麻油、含液晶材料4-正戊基-4'-氰基联苯(5CB)添加剂蓖麻油的磨损试验研究,分析了其磨斑直径WSD与负荷的变化规律,初步探讨了液晶添加剂5CB对蓖麻油的作用机理.结果表明:5CB能够改善蓖麻油的润滑性能,最大无卡咬负荷从490 N提高到784 N；当负荷高于784 N时,含3％5CB蓖麻油对应的WSD低于含l％5CB所对应的WSD；当负荷为1 536 N时,含3％5CB蓖麻油出现了烧结现象,而成品齿轮油产生1.28 mm的WSD.5CB添加剂能够改善蓖麻油的润滑性能,但尚不能完全达到或超过矿物油的润滑性能,需在今后的研究中继续改进.
关键词:
润滑性能
,
蓖麻油
,
液晶添加剂
,
4-正戊基-4'-氰基联苯
,
磨斑直径
,
重载工况
