Synthesis and microstructure control of bride-nitride composite ceramics by solid-state displacement reaction

固相置换反应制备氮化物复合陶瓷及其微观结构控制

基本信息

批准号：
11650691
负责人：
TAIMATSU Hitoshi
金额：
$ 1.79万
依托单位：
Akita University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

项目摘要

Reaction processes in the B_4C-Ti, BN-Ti and BN-Zr systems were examined for determining the most suitable reaction temperature and holding time for the syntheses of TiB_2-TiC-C, TiB_2-TiN and ZrB_2-ZrN composites with fine microstructure. For the TiB_2-TiC-C composites, their densification was tried by reactive hot pressing.For reactive hot pressing of powder mixtures of B_4C and Ti at 2000℃, different reaction products were formed by varying the Ti/B_4C mixing ratio x : B_4C-TiB_2-C at 0<x<2, TiB_2-C at x=2, TiB_2-TiC-C at 2<x<3 and TiB_2-TiC at x=3. Relative density had the minimum value 97.0% at x=2. Except for this mixing ratio, every sintered body was highly dense and had a relative density more than 98.4%.For the reaction between Ti and BN at 1100℃, TiB was first formed as an intermediate product and then TiB_2 was formed by the reaction between TiB and BN.N/Ti ratios of TiN_x in TiB_2-TiN composites were a little lower than those estimated from the mixing ratios. Because of this phenomenon, a little amount of BN always remained after reaction. The synthesis of a perfect TiB_2-TiN composite will need excessive addition of Ti.For the reaction between Zr and BN at 1100℃, the reaction ceased after a reaction time of 144 h. Syntheses in an Ar stream prefer to those in vacutun or in vacuumized capsule. The nonstoichiometry of ZrN_x decreased with the reaction time.

检查了B_4C-TI，BN-TI和BN-ZR系统中的反应过程，以确定TIB_2-TIC-C，TIB_2-TIN和ZRB_2-ZRN组成的合成的最合适的反应温度和保持时间与细微观结构。对于TIB_2-TIC-C组成，通过反应性热按下尝试了它们的致密性。对于B_4C和Ti的反应性热按2000℃时的反应性热按下，通过改变Ti/B_4c混合率x：B_4C-TIB_2-C在0 <x <2和tib_2-c，ti/b_4c混合率x：b_4c-tib_2-c在x <x <2 <x = 2，ti/b_4c混合率x： x = 3时的tib_2-tic。相对密度在x = 2时的最小值为97.0％。除了这种混合率外，每个烧结的身体都高度致密，相对密度超过98.4％。对于在1100℃处Ti和Bn之间的反应，TIB首先形成为中间产品，然后TIB_2由TIB和Bn.n/Ti率之间的TIB_X中的TIB_X之间的反应形成，而TIB_X与TIB_2 TIB_2 TIN的含量相比，该含量低于这些含量较低的含量。由于这种现象，反应后总是少量保留了少量的bn。完美的TIB_2-TIN复合材料的合成将需要过量添加Ti。对于1100°时ZR和BN之间的反应，反应时间在144 h后停止。 AR流中的合成更喜欢Vacutun或真空胶囊中的合成。 ZRN_X的非缩写计量法随反应时间降低。