溶融金属および鉄合金の有効放射率
1971 年 57 巻 7 号 p. 1198-1212
詳細
1971 年 57 巻 7 号 p. 1198-1212
When we measure temperatures of molten metals and alloys by using a disappearing filament type optical pyrometer through the optical system, we have to make calibrations because the observed temperatures are always lower than the true temperatures.
These calibrations consist of the emissivity and transmissivity corrections, since the emissivity depends on temperature, melt composition and measuring conditions, and the transmissivity changes according to the optical system used.
The apparent optical temperatures of four kinds of pure metals, eight kinds of Fe-X molten alloys and seven kinds of Fe-C-X molten alloys were measured in the atmosphere of argon in the present investigation, and the emissivities were calculated by using the WIEN'S equation:
ln(ε·τ)=C2/λ·(1/t+273-1/s′+273)
where ε is the emissivity, τ is the transmissivity, C2 is the PLANCK'S second constant for the black body radiation formula, (14380μ·deg)λ is the effective wave length (0.65μ), t is the true temperature (°C) and s' is the apparent optical temperature (°C).
The true temperatures of the melts were obtained by measuring the apparent optical temperatures of a cylindrical cavity in the magnesia crucible.
The transmivities of the optical systems (i. e. prism or sight glass+prism) were determined by the aid of the apparatus “Prismeter”.
