ON-LINE PROCESS CONTROL SENSOR FOR PARTICLE SIZE

A PARTICLE SIZE SENSOR IS REQUIRED FOR ON-LINE PROCESS CON- TROL IN A METAL POWDER FORMING FACILITY. INSTRUMENTS AVAILABLE COMMERCIALLY FOR THIS SENSING RELY ON MEASUREMENTS OF LIGHT SCATTERING AT VERY SMALL ANGULAR INCREMENTS. IT IS PROBABLE THAT THE HIGHLY TURBULENT ENVIRONMENT IN WHICH THE METAL POWDERS ARE FORMED WILL PRODUCE SUFFICIENT ANGULAR DE-VIATION OF THE PROBING LIGHT BEAM TO INVALIDATE SCATTERING MEASUREMENTS. THE METHOD WE PROPOSE DETERMINES THE PARTICLESIZE DISTRIBUTIONS BY THE SPECTRAL SHAPE OF TRANSMITTED IR RADIATION, AND IS RELATIVELY INSENSITIVE TO THE EFFECTS OF TURBULENCE. PARTICLE SIZE DISTRIBUTIONS FOR A NUMBER OF SAMPLES HAVE BEEN DETERMINED BY THE SPECTRAL METHOD. THE METHOD UTILIZES A FOURIER TRANSFORM INFRARED (FT-IR) SPECTROMETER FOR THE MEASUREMENTS, AND CAN MEASUREMENTS, AND CAN MEASURE A MEDIUMRESOLUTION SPECTRUM IN UNDER A SECOND. IN THE PHASE- I WORKWE WOULD EXTEND THE SPECTRAL METHOD FOR DETERMINING THE SIZEDISTRIBUTION TO METALLIC PARTICLES IN THE 1-200 UM RANGE. IN ADDITION, WE WOULD DETERMINE THE EFFECT, IF ANY, THAT A HIGHLY TURBULENT ENVIRONMENT HAS ON THE RESULTS OF THE METHOD. IN PHASE-II, THE METHOD WOULD BE AUTOMATED, AND A PROTOTYPE ON-LINE SIZE SENSOR FOR METALLIC PARTICLES WOULD BE BUILT. FUTURE POSSIBLE EXPANSIONS OF THE INSTRUMENT'S CABABILITIES INCLUDE TOMOGRAPHY FOR SPATIALLY RESOLVED PAR- TICLE SIZE DISTRIBUTIONS, ANALYSIS OF TRANSIT-TIME "NOISE SPECTRA TO OBTAIN PARTICLE VELOCITIES, AND THE ADDITION