• Title/Summary/Keyword: Iron silicide

Search Result 13, Processing Time 0.018 seconds

Phase Transformations and Oxidation Properties of Fe$_{0.98}$Mn$_{0.02}$Si$_2$ Processed by Mechanical Alloying (기계적 합금화법에 의해 제조된 Fe$_{0.98}$Mn$_{0.02}$Si$_2$의 상변태와 산화특성)

  • 심웅식;이동복;어순철
    • Journal of the Korean institute of surface engineering
    • /
    • v.36 no.2
    • /
    • pp.200-205
    • /
    • 2003
  • Thermoelectric p-type $Fe_{0.98}$ $Mn_{ 0.02}$$Si_2$ bulk specimens have been produced by mechanical alloying and consolidation by vacuum hot pressing. The subsequent isothermal annealing was not able to fully transform the mestastable as -milled powders into the $\beta$ $-FeSi_2$ phase, so that the obtained matrix consisted of not only thermoelectric semiconducting $\beta$-FeSi$_2$ but also some residual, untransformed metallic $\alpha$ $- Fe_2$$Si_{ 5}$ and $\varepsilon$-FeSi mixtures. Interestingly, $\beta$ - $FeSi_2$ was more easily obtained in the low density specimen when compared to the high density specimen. The oxidation at 700 and $800^{\circ}C$ in air led to the phase transformation of the above described iron - silicides and the formation of a thin silica surface layer.

Microstructure Analysis of Carbon Nanotubes Grown by Plasma Enhanced Chemical Vapor Deposition (플라즈마 화학기상증착법으로 성장시킨 탄소나노튜브의 미세구조 분석)

  • Yoon Jongsung;Yun Jondo;Park Jongbong;Park Kyeongsu
    • Korean Journal of Materials Research
    • /
    • v.15 no.4
    • /
    • pp.246-251
    • /
    • 2005
  • Plasma enhanced chemical vapor deposition(PE-CVD) method has an advantage in synthesizing carbon nanotubes(CNTs) at lower temperature compared with thermal enhanced chemical vapor deposition(TE-CVD) method. In this study, CNTs was prepared by using PE-CVD method. The growth rate of CNT was faster more than 100 times on using Invar alloy than iron as catalyst. It was found that chrome silicide was formed at the interface between chrome layer and silicon substrate which should be considered in designing process. Nanoparticles of Invar catalyst were found oxidized on their surfaces with a depth of 10 m. Microstructure was analyzed by scanning electron microscopy, transmission electron microscopy, scanning transmission electron microscopy, and energy dispersive x-ray spectrometry. Based on the result of analysis, growth mechanism at an initial stage was suggested.

Joining of Silicon Nitride to Carbon Steel using an Active Metal Alloys (활성 납재를 이용한 질화규소/탄소강 접합)

  • Choe, Yeong-Min;Jeong, Byeong-Hun;Lee, Jae-Do
    • Korean Journal of Materials Research
    • /
    • v.9 no.2
    • /
    • pp.199-204
    • /
    • 1999
  • As the engine design change to get high efficiency and performance of commercial diesel engine, surface wear of the cam follower becomes an important issues as applied load increasing at the contact face between cam follower and cam. Purpose of this study is the developing of the ceramic cam follower made of silicon nitride ceramic which is more wear resistant than the cast iron and sintered cam follower. Ceramic cam follower was made by direct brazing of thin ceramic disk to steel can follower body using active bracing alloy. Effect of joining condition on the interfacial phases and joining strength wer examined at bvarious joining temperatures, times, and cooling rates. Crowning resulted from the difference of thermal expansion coefficient after direct brazing without using any stress-relieving inter layer was measured. Interfacial phases are mainly titanium silicide and titanium nitride which are the products between active metal(Ti) in brazing alloy and silicon nitiride. Maximum joining strength of the ceramic metal joint, measured by DBS method, was 334MPa. Crowning(R) of the prototype ceramic cam follower was 1595mm. As machining for crowning is not necessary, production cost can be reduced.

  • PDF