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Consolidation of Hard Sinterable Materials and Near Net Shape Forming by Pulsed Current Pressure Sintering (PCPS) Process.

通过脉冲电流压力烧结 (PCPS) 工艺固结硬质可烧结材料并实现近净形状成型。

基本信息

批准号：
13555203
负责人：
YOKOTA Masaru
金额：
$ 6.98万
依托单位：
Takaoka National College
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

The Pulsed Current Pressure Sintering (PCPS) is well known as rapid sintering process. This is a kind of hot pressing which employs the pulsed electric current to heat materials. It is suggested to be characterized by four major advantages over the conventional consolidation techniques, i.e. : (1) preservation of original microstructures after consolidation, (2) high density consolidation in a short time, (3) removal of adsorbed materials on the powder surface, (4) improved mechanical properties resulted from these (1)-(3) items. We employed the PCPS process to consolidate the aluminum alloy powder and attained the high strength sintered specimen. Furthermore, hollow shaped compacts and functionally graded Al/Al2O3 materials were formed by PCPS. Principal results obtained are as follows :(1) The maximum tensile strength of PCP sintered compact was over 9OMPa and the elongation was 50%. This value outweigh that of 1000 series Al wrought alloys.(2) PCP sintering process can densify Al powders in a short time compared to the HP sintering process. Mechanical properties of the compacts outweigh the HP compact.(3) The hollow compacts having an intricate shape were obtained by a one-pass process of PCPS sintering using the core made of h-BN or graphite powders because of their good compactibility and difficultly sinterable properties.(4) The Al/Al_2O_3 FGM composed of a dense a-Al_2O_3 layer and seven gradient intermediate layers was successfully fabricated from starting materials consisting of aluminum and Al(OH)_3 powders by employing a temperature gradient PSPC process with a copper spacer, at a pressure of 49 MPa, and with the short sintering time of 900 sec. The hardness of the aluminum layer was about 25 HV. The hardness of intermediate layers gradually increased as the volume fraction of r-Al_2O_3 increased. The top layer, which consists of dense a-Al_2O_3, was about 1000 HV on average, and the top surface of the specimen reached 1500 HV.

脉冲电流压力烧结（ppps）是一种众所周知的快速烧结工艺。这是一种利用脉冲电流加热材料的热压。与传统的固结技术相比，该技术具有以下四个主要优点：(1)固结后保留了原始的微观结构；(2)在短时间内高密度固结；(3)去除了粉末表面的吸附物质；(4)这些(1)-(3)项提高了力学性能。采用ppps工艺对铝合金粉末进行固结，获得了高强度的烧结试样。在此基础上，制备了空心压块和功能梯度Al/Al2O3材料。主要研究结果如下：(1)PCP烧结坯的最大抗拉强度大于9OMPa，伸长率为50%。该值超过了1000系列铝变形合金。(2)与HP烧结工艺相比，PCP烧结工艺可以在短时间内致密化Al粉末。紧凑的机械性能超过惠普紧凑。(3)由于h-BN或石墨粉具有良好的压实性和难烧结性，采用ppps一次烧结工艺获得了形状复杂的空心压实件。(4)以铝和Al(OH)_3粉末为原料，采用温度梯度PSPC工艺，在49 MPa的烧结压力下，以铜为间隔，成功制备了由a-Al_2O_3致密层和7个梯度中间层组成的Al/Al_2O_3 FGM，烧结时间仅为900秒，铝层硬度约为25 HV。随着r-Al_2O_3体积分数的增加，中间层硬度逐渐增大。试样表层由致密的a-Al_2O_3组成，平均温度约为1000 HV，试样表面温度达到1500 HV。