Evaluation of pore Characterization in Powder Metallurgical Products Using Ultrasonic Scattering

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The purpose of this investigation is to develop an non-destructive method for evaluating pore structures of porosity and/or pore size of induatrial sintered compacts by using ultrasonics. For this purpose, the suthors tried to introduce an ultrasonic spectroscopy of ultrasonic attenuation and velocity measurement. Six Cu-sintered compacts with different pore size were prepared for this study. These were made of gass-atomized copper powder of 400 <micrn> m in diameter. The structure of these compacts was simple, dual phase with pore and matrix (Cu), and was the most suitable sample for the first step to establish the method of ultrasonic pore structural charaterization for industrial sintered compacts. In order to evaluate the pore structures in paticular from the ultrasonic attenuation spectrum, the attenuation spactrum must be estimated quantitatively. In this study, "Spectrum Shifting Method" was investigated as the quantitative estimation method of attenuation spectrum. As the results, the mean pore diameter could be evaluated from the ultrasonic attenuation by using "Spectrum Shifting Method", and the poeosity could be estimated from ultrasonic velocity mesurement.