Surface Temperature Measurement of Semi-Transparent Ceramics by Long-Wavelength Pyrometry

Abstract
A procedure using a long-wavelength pyrometer is developed for the measurement of surface temperatures on materials that are semitransparent at shorter wavelengths, and specific application is made to a dense zirconia ceramic (Mg-PSZ) undergoing laser-assisted machining (LAM). The pyrometer operates in a waveband between 11 and 14 μm, and a detailed description of measurement uncertainties is provided. The largest uncertainties relate to knowledge of the surface emissivity and the large temperature gradients generated by the LAM process. Repeatability of the measurements is demonstrated, and a parametric study of three LAM parameters reveals expected trends.