| 摘要 |
1281675 Sintering cemented carbide E I DU PONT DE NEMOURS & CO 24 June 1970 [31 July 1969] 30720/70 Heading C7D Green compacts of 97-75% WC with 3-25% CO and a green density > 30% theoretical are vacuum presintered to between 1100‹C and the eutectic temperature at a heating rate not more than 10‹C/minute. They are the vacuum sintered at temperature T s for not more than 10 minutes and raised to Ts at a rate R s = (1.25M + 45) Œ10‹ C. per minute; where T s = The sintered body is cooled from T s to 800‹ C. in an oxygen free atmosphere in 4-30 minutes. The WC and CO have particle sizes 0.1-2 microns and 0.1-5 microns respectively. The powder mixture has a specific surface area of 1-7 sq. m/gm. and an oxygen content <1% net. The powders after conventional wet ball milking and drying are compacted at 1, 000-100, 000 p. s. i. either hydraulically or isistatically. |
