텅스텐 제조를 위한 소결공정의 영향과 기계적 특성 평가

Abstract

The monolithic tungsten materials were fabricated by a hot pressed sintering process using a chromium powder as an additive material in this study. Especially, mechanical properties of tungsten materials including the flexural strength and hardness were evaluated due to the sintering temperature and the effect of additive amount. SEM was also used to analyze the microstructural characteristics of the sintered tungsten material. It was found that both sintered density and flexural strength of tungsten materials increased with the increase in sintered temperature and additive Cr amount, accompanying to the grain growth in the microstructure. The relationship between microstructure and mechanical properties of flexural strength is discussed for producing the optimal fabricating condition of tungsten materials. The bending strength and Vickers hardness of tungsten sintered material increased with increasing sintering temperature. The bending strength of the tungsten sintered material was about 580 MPa and the Vickers hardness was about 470 Hʋ when 7 wt% of chromium powder was added at sintering temperature of 1,600℃. At the sintering temperature of 1,600℃, the sintering density of tungsten sintered material increased with promotion of microstructure densification as the content of chromium added to tungsten powder increased. In particular, it showed excellent sintered density of about 17.04 g/㎤ at a chromium content of 7 wt%.