A Method for Evaluation for the Component Uniformity of a Powder Mixture by Micro Fourier Transform Infrared Spectrometry

A method for evaluating the uniformity of a small volume of the components of four kinds of zirconia and silica powder mixture in the range of 10-3-10-5mm3 was investigated using Micro Fourier transform infrared (micro-FTIR) reflectance spectrometry. The respective ten micro-FTIR reflectance spectra (spot size is 250×250μm2) of different locations in a sample were measured, and the relative standard deviation (RSD) of the peak height ratios (1100cm-1: assign to Si-O vibration/600cm-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 25×25μm2) for every sample, and the relationships between the RSD values and measuring volume which was estimated from spot size were obtained. The least volumes (regarded as uniform) were obtained for each sample, respectively.