Synthesis
The TaSi2 powder preparation method includes the following steps: -500 mesh silicon powder and -300 mesh tantalum powder are weighed according to the stoichiometric ratio of TaSi2. Here, in order to obtain a high purity product, high purity silicon powder and tantalum powder need to be selected, such as 99.95 or 99.99% purity. The choice of -500 mesh silicon powder with -300 mesh tantalum powder is to better mix the silicon and tantalum, so that the tantalum particles are surrounded by the silicon particles, which is conducive to easier contact and reaction between the silicon and tantalum in the later steps of combustion synthesis. The use of stoichiometric matching is to obtain the TaSi2 phase. In the case where both -200 mesh or -300 mesh silicon and tantalum powders are used, it is difficult to obtain a completely single-phase TaSi2 phase powder, and there will always be a small amount of Ta5Si3 phase. The use of smaller particle size raw material powder can make the reaction more complete, but this increases the powder oxygen content, but will hinder the synthesis reaction. Specific steps are as follows: weigh -500 mesh silicon powder 23.6 g and -300 mesh tantalum powder 76.4 g; add NH4Cl powder that accounts for 0.5 g of the weight of silicon powder and tantalum powder; ball-mill the above powder, the ball material ratio of 8:1, ball milling time of 12 hours; the ball-milled powder is loaded into the crucible of silicon carbide, and put on the shaking table and vibration to the relative density of 40%; the crucible containing the powder is loaded into the synthesis furnace After vacuuming, the crucible was filled with argon gas, and the temperature was raised to 650 at 20 per minute, and the tantalum silicide synthesis reaction was ignited by tungsten wire energization; after cooling, the final powder product was obtained by crushing with zirconium oxide balls and cans, and all of the products were tantalum silicide phases detected by XRD.
