Ti-Si多孔材料的燃烧合成与孔隙结构特征

Combustion Synthesis and Structure of Porous Ti-Si Intermetalics Material

以Ti、Si元素粉末为原料，采用燃烧合成技术制备了Ti-Si原子配比分别为1：1、5：4、5：3、3：1的4种多孔材料，对其燃烧合成特征、相组成、孔结构以及微观形貌进行了分析。结果表明：随着Ti含量的增加， Ti-Si体系反应程度先加剧后减弱，燃烧温度表现为先升高后降低的变化趋势，最高燃烧温度达2075K；燃烧产物分别以TiSi、Ti5Si4、Ti5Si3、Ti5Si3相为主。多孔材料开孔率为42．43％～49．42％，体积中值孔径处于64．10～18．11gm；抗压强度最高达到23．15MPa。造孔机制主要包括粉末压坯颗粒间的原始孔隙；燃烧合成反应过程中先熔化的硅颗粒在毛细作用下发生流动形成的原位孔隙；原位孔隙和颗粒间原始孔隙结合形成的大孔隙；燃烧合成过程中因熔化析出作用导致摩尔体积下降形成的小孔隙。

Porous Ti-Si materials were prepared by a combustion synthesis method. The atomic ratios of Ti：Si were 1：1, 5：4, 5：3 and 3：1. The combustion characteristics, phase composition, pore structure and microstructure of the products were investigated. It is found that, with the increase of Ti content, the rate of the combustion wave and the combustion temperature first increase and then decrease, and the highest combustion temperature is 2075 K. The main products are TiSi, TisSi4, TisSi3 and TisSi3 at the Ti：Si atomic ratios of 1：1, 5：4, 5：3 and 3：1, respectively. The open porosities of the products are within the range of 42.43%-49.42%. The median pore diameters are within the range of 64.10-18.11 Ixm and decrease with the increase of Ti content. The highest compressive strength is 23.15 MPa. The main pore formation mechanism includes the residual pores among the particles of the powder compacts, and the in situ pores owing to the molten silicon particles flowing during the combustion synthesis reaction. The large pores are formed by the interstitial hole combining with the in situ pores, and the small pores are formed by the decrease of the molar volume during the solution-precipitation process.