纳米钨粉的烧结工艺

采用催化-凝胶法制备的平均粒径60nm的纳米钨粉为原料,经钢模压制成生坯,用高温膨胀仪测定了纳米钨粉坯体的烧结收缩动力学曲线;然后分别测定了不同烧结温度和烧结时间下烧结体晶粒尺寸和相对密度的变化.结果表明,纳米钨粉的坯体在200℃开始收缩,1300℃基本停止收缩.从1000℃到1200℃,其相对密度提高了24%,是致密化过程最快的阶段.在1200℃×120min的烧结工艺下得到烧结体相对密度为95%,晶粒尺寸为5μm的钨材.

Sintering process of nanoscale tungsten powder

Nanosized tungsten powder with a mean particle size of 60 nm, which was prepared by catalysis-gel process, was used as raw material. After compacted with a steel die, the green compact was sintered in hydrogen in order to investigate its shrinkage kinetic curve. The changes of grain size and relative density during sintering at different temperatures for different sintering time were tested. It is shown that the compact of nanosized tungsten powder starts to shrink at 200℃ and stops shrinking at 1 300℃. The highest shrinkage rate occurs at 1225℃. From 1 000℃ to 1200℃, the relative density increases by 24%. After sintered at 1200℃ for 120 min, the average grain size is 5μm, and the relative density is 95%.