Study On Fabrication Of Ti₃Si₂ Ceramic

In the present research, two series of raw materials (a) using the elemental Ti,Si and C powders as raw materials (b) using Ti,SiC,and C powders, were used to fabricate TisSiCiby spark plasma sintering, and hot pressing respectively. In order to find the ideal synthesis conditions, different raw materials ratios in molar and various sintering temperatures were investigated. Additionally, effects of Al and sintering temperatures on the synthesis, and the crystal growth of TisSiCi were especially studied.The sintered product was characterized by XRD method to determine the phases and lattice parameters. The microstructures of the samples were investigated via scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS) for chemical analysis. The chemical binding state of the samples were analyzed by X-ray photoelection spectroscopy. In addition, some properties of the pure product (the density, Vickers hardness, electrical conductivity, machinability) were measured respectively.It could concluded that the addition of Al(0.05-0.2mol) was in favor of the synthesis, and the crystal growth of Ti3SiC2 below 1300 when the elemental Ti,Si and C powders were used as raw materials. And the effects increased with the addition amount of Al in the range of 0.05-0.2 mol of Al. Importantly, the purity of products was improved with the addition of Al. It was found that maximum solid solution of Al in Ti3SiC2 was below 0.3 mol, and the solid solution of Al decreased thermal stability of Ti3SiC2, and the temperature at which TisSiC2 decomposed was lower than 1300 .Pure Ti3SiC2 materials was synthesized by spark plasma sintering of elemental powder mixture with a composition of Ti: Si: Al: C=3: 1:(0.1- 0.2): 2 in molar ratio. The ideal synthesis temperature ranged from 1150 to 1250, which was the lowest temperature for fabricating pure Ti3SiC2 material so far. The lattice parameters of TiaSiC2 prepared here were a=0.3066nm, c=1.767nm. Ti3SiC2 was in plane-shape with the grain size of. The obtained material had fine electrical conductivity, Vickers hardness of 4.64GPa, and it could be easily machined by using ordinary mechanical machining tools.On the other hand, the synthesis of TJ3SiC2 had higher reaction activation energy, and required higher sintering temperature when SiC instead of Si was used. It was difficult to obtain pure Ti3SiC2 by spark plasma sintering in such case. And the addition of Al had little effect on the synthesis reaction.Spark plasma sintering is an advanced technology for materials synthesis. The mutual relation of process parameters was studied. Vacuum pressures vs. temperature, Z-displacement vs. sample temperature, as well as Z-displacement vs. soak time, were used to investigate the reaction synthesis and the sintering situation mechanism with these parameters.Using elemental powder mixture with a composition of Ti: Si: Al: C=3: 1:0.2:2 in molar ratio as raw materials,investigation on the synthesis of TisSiC2 by hot pressing showed the products had impurity of TiC at various sintering temperatures.