Measurements of total hemispherical emissivity of various oxidized metals at high temperature

William R. Wade
naca-tn-4206
Mar 1958


The results of measurements of total hemispherical emissivity at high temperatures for various metals are presented, together with a limited description of the equipment and procedures used. The metals included are stainless steel (AISI 303), mild steel, (AISI C1020), titanium (TMCA Ti-75A), titanium alloy (RS-120), copper, aluminum (AA 3003), molybdenum, and tantalum. The variation of total hemispherical emissivity due to oxidation of the metal was determined for the highest temperature which would produce an adherent oxide coating of stable emissivity. It was found that at a given temperature the emissivity increases as the exposure time at this temperature increases until a stable value is reached. Deviation of the thermal radiation from Lambert's cosine law of diffuse emission was investigated, and values of total hemispherical emissivity were obtained for specimens possessing a surface of stable emissivity.

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