چكيده به لاتين
Because of titanium carbide hardness and high melting point, low density and high electrical conductivity, it's suitable for the preparation of silicon nitride composites. Titanium carbide nanopowders by sol-gel method using tetra-butyl ortho titanate as titanium source and sucrose as a carbon source was synthesized. The sol-gel process was controlled by Ethyl acetate. Yellow sol was taken for 24 hours in an air atmosphere on magnetic to achieve gel. The gel dried. To check links in the obtained dried gel, infrared spectrum was taken. The gel obtained was calcined in air to obtain amorphous carbon nanopowders with tetragonal anatase. The heat treatment of gel of anatase and amorphous carbon in 1000-1400 ℃ for 2 hours in an argon atmosphere + 25% hydrogen, with increasing temperature, respectively intermediate phases, oxy-phase titanium carbide and finally titanium carbide obtained. Microstructural studies were conducted on nano-powder particles with particle size of approximately 40 nm showed almost uniform. Dynamic light scattering analysis was performed to evaluate the average size distribution of nanoparticles.
In order to discharge Mashining of silicon nitride ceramics, titanium carbide nanopowders was added with values of 15, 25 and 35% by volume. Aluminum oxide and yttrium oxide as a sintering aid was used. Sintered samples at 1700 ℃ with a time of 20 minutes in a vacuum plasma sintering was done. The highest density was obtained for samples containing 35 volume percent TiC. This model also has the lowest electrical resistance. This sample also had the highest amount of flexural strength. By increasing the volume percentage of TiC of 15 to 35, the flexural strength of 710 to 870 MPa, micro-hardness of 17/5 Gpa to 19/5 GPa and the relative density of the samples increased from 98 to 99/45% of theoretical density. The fracture toughness varying from 15 to 35 volume percent TiC, was almost unchanged, but the fracture toughness of the silicon nitride rose. Electrical discharge machining method successfully was performed on optimal sample (35% by volume TiC).
