纳米陶瓷的热压烧结及超塑成形(英文)

纳米陶瓷具有优良的室温和高温力学性能 ,如较高的抗弯强度、断裂韧性、耐磨性等 ,使其在切削刀具、轴承、高温发动机部件等诸多方面都有广泛的应用。利用纳米陶瓷的超塑性进行成形加工是实现复杂形状零件近净成形的重要手段。本文采用化学沉淀法制备了平均粒径 10nm ,且无硬团聚的 3Y TZP (3%摩尔氧化钇稳定的四方相氧化锆多晶体 )粉体 ,研究了不同密度素坯的热压烧结行为。 3Y TZP毛坯的超塑性拉深试验表明在 14 5 0℃压头速率为 0 2mm·min-1时可以实现半球形件的成形 ,其成形高度达到 5 7mm ;Al2 O3 ZrO2 纳米复相陶瓷的正挤压试验表明 ,这种典型的晶间 /晶内型纳米陶瓷在很高的温度下可以 0 . 5mm·min-1的压头速率进行挤压成形 ,在某种程度上可以满足工业成形的需求 ;Si3 N4 Si2 N2 O复合陶瓷通过烧结锻造可以成形陶瓷齿轮 ,其烧结温度为 16 0 0℃ ,超塑性锻造温度为 15 5 0℃。

Hot-press sintering and superplastic forming of nano-ceramics

Nano-ceramics have excellent mechanical properties (high flexural strength, high fracture toughness, wear resistance, et al.) not only at ambient temperature but also at elevated temperature, which make them widely used in cutting-tools, bearing and engine components, et al. Complicated shape components can be made of nanocomposite ceramic by using its superplasticity, which is an important way in near-net shape forming. Nano-sized 3Y-TZP powders with average grain diameter of 10nm and soft agglomeration were synthesized by chemical precipitation. Discs with different initial density were sintered by hot-press sintering. Superplastic deep drawing test demonstrates that dense 3Y-TZP discs can be elongated to a dome height of at least 5.7mm at the punch rate of 0.2mm*min -1 at 1450℃. In constrained extrusion Al2O3/ZrO2 composite, a typical intra/inter granular nanocomposite, can deform at a high punch rate of 0.5mm/min at the enhanced temperature, which will satisfy the industrial forming in some extent. Gears made of Si3N4-Si2N2O composites can be formed by sinter-forging technology when the sintering temperature is 1600 ℃ and superplastic forging temperature is 1550 ℃.