TiH_2做Ti源合成Ti_2AlC/Ti_3AlC_2及热分析

Synthesis of Ti_2AlC/Ti_3AlC_2 from TiH_2 as Ti Source and Thermoanalysis

廉价TiH2是制造钛粉的中间产物。本文用TiH2取代钛粉在常压下高温合成一种先进陶瓷材料-钛铝碳(Ti2AlC和Ti3AlC2)。以配料3TiH2/1.5Al/C或2TiH2/1.5Al/TiC为原料,在1400℃保温120 min可合成高纯Ti2AlC。原料3TiH2/1.2Al/2C在1400℃保温120 min和TiH2/1.2Al/2TiC在1350℃保温120 min均可制备高纯的Ti3AlC2。差示扫描量热法(Differential Scanning Calorimetry)被用来分析Ti-Al-C反应体系热量变化。在配料3TiH2/1.5Al/C反应过程中,Ti2AlC合成反应的放热峰消失;表明TiH2脱氢反应所吸收的热量与TiC或Ti2AlC的合成反应所释放的热量相互弥补。以TiH2为Ti源在一定程度上不仅可以降低原料成本,还可以减少或避免大批量生产钛铝碳过程中的热爆现象。

TiH2 powders are the intermediate products to make metallic Ti powders and much cheaper than Ti powders. In this paper, TiH2 powders, instead of Ti powders, was employed to synthesize titanium aluminum carbides （TiiAlC and Ti3AlC2 ） by a tube furnace. High pure Ti2AlC was fabricated from 3TiH2/1.5Al/C and 2TiH2/1.5Al/TiC powders at 1400 ℃ for 120 min. Ti3AlC2 was synthesized from 3TiH2/1.2Al/2C at 1400 ℃ and TiH2/1.2Al/2TiC at 1350 ℃ both for 120 min. The as-synthesized samples were porous and easy to be made into powders. The reaction mechanisms were studied by Differential Scanning Calorimetry （DSC）. There is no obvious exothermic peak for Ti2AlC. The endothermic process of TiH2 dehydrogenation weakens the exothermic process of TiC/Ti2AlC synthesis. This method not only can reduce the cost of raw materials but also, to a certain degree, avoid the thermal explosion during Ti2AlC/Ti3AlC2 mass production.