A method for evaluation of the component uniformity of a powder mixture by micro Fourier transform infrared spectrometry

A method for evaluating the uniformity of a small volume of components of four kinds of zirconia and silica powder mixture in the range of 10−3 to 10−5 mm3 was investigated using micro-Fourier transform infrared (micro-FTIR) reflectance spectrometry. Reflectance spectra (spot size 250 × 250μm2) were taken from 10 different locations within a sample and the relative standard deviation (RSD) of the peak height ratio (1100 cm−1: assign to Si-O vibration/600 cm−1: assign to Zr-O vibration) was calculated for each sample. If the RSD value was below the error that accompanied the measuring method (about 3%), the sample was regarded as uniform. The above operation was repeated with diminishing spot size (80 × 80 and 25 × 25 μm2) for each sample, and the relationship between the RSD values and measuring volume, which was estimated from spot size, was obtained. The least volumes (regarded as uniform) were obtained for each sample.