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Preparation of cBN-Diamond Composite Sintered Compact by Reaction Sintering

反应烧结制备立方氮化硼-金刚石复合烧结体

基本信息

批准号：
02650556
负责人：
ITOH Hideaki
金额：
$ 1.02万
依托单位：
Nagoya University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02650556/
关键词：
Cubic Boron Nitride Diamond Reaction Sintering Composite Sintered Compact High Pressure Treatment Volatile Catalyst ヒ-トシンク

项目摘要

An objective of the present research is to prepare a composite sintered compact in the cBN-diamond system in which fine diamond particles are dispersed homogeneously in the reaction sintered cBN matrix.1. Optimum reaction sintering conditions : The starting powder of hBN and diamond (0-90 wt%) which were mixed with various kinds of volatile catalysts was treated under high pressure and temperature conditions (6-7.5 Gpa, 1300-1700ﾟC, 0-30 min). The optimum sintering conditions were found to be 7 GPa, 1700ﾟC and 15-30 min.2. Microstructure and properties of the sintered compacts : Conversion from hBN to cBN increased with decreasing diamond grain size and increasing diamond content. The microhardness increased as the diamond content increased, but the toughness decreased because of a weak particle bonding between cBN and diamond grains. A sintered compact with the composition of 70 wt% cBN - 30 wt% diamond showed the conversion of 99 %, the relative density of 99 % and Vickers microhardness of 5100 kg/mm^2.3. Effects of volatile catalysts : The effects of volatile catalysts were investigated by adding 0-30 wt% NH_4NO_3, NH_4Cl and NH_2NH_2 under the above optimum sintering conditions. An excess addition of NH_4Cl deteriorated the properties of sintered compact because of increased amount of non-ammonium components. An activation energy required for the conversion from hBN to cBN was 200-230 kJ/mol. NH_X components in these catalysts which decomposed under high pressure and temperature conditions, would play an important role in the conversion from hBN to cBN.

本研究的一个目的是制备一种cBN-金刚石体系复合烧结体，其中细小的金刚石颗粒均匀地分散在反应烧结的cBN基体中。 1．最佳反应烧结条件：将六方氮化硼和金刚石（0-90 wt%）的起始粉末与各种挥发性催化剂混合，在高压和高温条件下（6-7.5 Gpa，1300-1700°C，0-30 min）进行处理。最佳烧结条件为7 GPa、1700℃、15-30 min.2。烧结体的微观结构和性能：随着金刚石晶粒尺寸的减小和金刚石含量的增加，从六方氮化硼到立方氮化硼的转化率增加。随着金刚石含量的增加，显微硬度增加，但由于 cBN 与金刚石晶粒之间的颗粒结合较弱，韧性降低。组成为 70 wt% cBN - 30 wt% 金刚石的烧结体的转化率为 99%，相对密度为 99%，维氏显微硬度为 5100 kg/mm^2.3。挥发性催化剂的影响：在上述最佳烧结条件下，添加0-30wt%的NH_4NO_3、NH_4Cl和NH_2NH_2，考察了挥发性催化剂的影响。过量添加NH_4Cl会导致非铵成分含量增加，导致烧结体性能恶化。从hBN转化为cBN所需的活化能为200-230kJ/mol。这些催化剂中的NH_X组分在高压和高温条件下分解，在六方氮化硼向立方氮化硼的转化中发挥重要作用。