材料
Online ISSN : 1880-7488
Print ISSN : 0514-5163
ISSN-L : 0514-5163
バルブシート用焼結合金の熱定数の測定
平沢 良男竹越 栄俊井村 定久清田 文夫
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1984 年 33 巻 375 号 p. 1559-1565

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The iron base sintered alloy, which contains a dispersed hard phase, is frequently employed in the valve seat for engine because it has superior wear-resistance. Since the valve seat is exposed to an exhaust gas and becomes high temperature, the measurements of its thermal properties are very important for the analysis of the temperature distribution which affects the thermal stress and thermal strain.
In the present study, several specimens of the sintered alloy having different porosities were prepared. Further, for a few specimens copper alloy was penetrated in the pore. The specific heat and the thermal diffusivity of the specimens were measured in the range from room temperature to about 800°C and the thermal conductivity was determined by calculation from these measured values.
The results obtained are summarized as follows:
(1) The specific heat of the sintered alloy increased rapidly with increasing temperature and had a transformation point at about 750°C where the specific heat became maximum. At high temperatures, the specific heat of the copper alloy penetrated specimen was slightly larger than that of the non-penetrated specimen.
(2) The thermal diffusivity decreased with increasing temperature and had also the transformation point at about 750°C where the thermal diffusivity became minimum. The diffusivity increased with increasing density and was largest in the copper alloy penetrated specimen.
(3) The thermal conductivity increased with increasing density, but changed little with increasing temperature except the copper alloy penetrated specimen.

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