Consolidation of low-sinterability powders with applying medium isostatic pressure

通过施加中等等静压来固结低烧结性粉末

基本信息

批准号：
06452331
负责人：
WATANABE Ryuzo
金额：
$ 4.86万
依托单位：
TOHOKU-UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1996
项目状态：
已结题

项目摘要

Sintering experiments were conducted on various alloys and ceramics powders using a sintering furnace with controllable atmosphere and pressure of ambient to 10kg/cm^2. The effects of powder characteristics, sintering temperature, applied pressure, sintering time, and heating and cooling conditions on the relative density and grain size of the sintered compacts. Iron alloy and super alloy powder could be densified to full density with pressure of 10kg/cm^2. Tool alloy powder of metal/boride system could not be sufficiently densified with such low pressure, and the higher pressure up to 500kg/cm^2 was necessary for the full densification. The grain structures, distributions of residual pores, shape and size of the precipitate were quantifield with an image analyzer, the sintering mechanisms during the microstructural evolution was studied. The sintering shrinkage rate was measured by non-contact-type dilatometric analyzer, and with the aid of the computer simulation of sintering densification kinetic equations for the shrikage rate were derived. At present the agreement between the simulation and the experimental is not good. However, the nature of the driving force for the densification was clarified, and the semi-quantitative discussion can well be made about the effect of applied pressure on the densification enhancement. For the further understanding of the sintering mechanisms a sintering map which takes into account the effects of sintering temperature, pressure, time and atmosphere has been constructed. With this sintering map the effect of pressurizing has been discussed in correlation with sintering mechanisms.

采用气氛可控、环境压力为10kg/cm^2的烧结炉对各种合金和陶瓷粉末进行了烧结实验。粉末特性、烧结温度、施加压力、烧结时间以及加热和冷却条件对烧结体的相对密度和晶粒尺寸的影响。铁合金和高温合金粉末在10kg/cm^2的压力下可致密至全密度。金属/硼化物系工具合金粉末在如此低的压力下无法充分致密化，需要高达500kg/cm^2的较高压力才能完全致密化。利用图像分析仪对晶粒结构、残余气孔分布、析出相的形状和尺寸进行量子分析，研究了微观结构演变过程中的烧结机制。采用非接触式膨胀分析仪测量烧结收缩率，并借助计算机模拟，推导出收缩率的烧结致密化动力学方程。目前模拟与实验之间的一致性并不好。然而，致密化驱动力的本质得到了澄清，并且可以很好地对施加压力对致密化增强的影响进行半定量讨论。为了进一步了解烧结机制，构建了考虑了烧结温度、压力、时间和气氛影响的烧结图。通过该烧结图，我们讨论了与烧结机制相关的加压效果。