| 摘要 |
PROBLEM TO BE SOLVED: To optically measure carbon concentration with extremely high accuracy in a short time by measuring the refractive index of the surface of a material to be carburized with time, computing the carbon concentration of the surface of the material to be carburized from the absolute value of the refractive index, also computing the carburizing velocity from the temporal change of the refractive index, and performing feedback control by using them as carburizing control factors. SOLUTION: The refractive index (n) of the surface of a material to be carburized shows a relation of monotone increase with respect to the carbon concentration (carburizing concentration) of a carburized layer; and the temporal change of the refractive index of the surface of the material to be carburized, d.n/dt, shows a relation of monotone increase with respect to carburizing velocity. During carburizing treatment, the surface of the material to be treated is irradiated with polarized light in the visible region and the reflected light is measured to compute the reflective index and carbon concentration of the surface of the material to be treated, and feedback control is carried out using them as carburizing control factors. During carburizing treatment, the measurement of carbon concentration and the immediate control of the state of carburizing are made possible. Gas carburizing and plasma carburizing can be effectively used for carburizing treatment equipment, and a carburized layer of desired quality can be obtained by making the conditions of control correspond to the measured results of carburizing concentration and carburizing velocity.
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