Fabrication of Functionally Graded Ti_3SiC_2-TiC Binary-Phase Material
Ti<SUB>3</SUB>SiC<SUB>2</SUB>–TiC binary-phase material was investigated with the aim of developing a new hard product. The starting material for the synthesis was prepared by compounding raw powders of Ti, Si and TiC at molar ratios of 1:1:<I>x</I> (<I>x</I>=1.8–7.0). The products were synthesized by sintering and the structures of the samples produced were examined. The product obtained was single-phase Ti<SUB>3</SUB>SiC<SUB>2</SUB> when <I>x</I> was 2.0 or less and a Ti<SUB>3</SUB>SiC<SUB>2</SUB>–TiC binary-phase structure when <I>x</I> was more than 2.0. The mass fraction of TiC in the binary-phase structure increased with increasing <I>x</I>. The optimum sintering temperatures for densification were different for the different synthesized structures: the Ti<SUB>3</SUB>SiC<SUB>2</SUB> single-phase structure was well densified at up to 1673 K, whereas higher temperature was required to dinsify the Ti<SUB>3</SUB>SiC<SUB>2</SUB>–TiC binary-phase structure. These results suggest the possibility of producing Ti<SUB>3</SUB>SiC<SUB>2</SUB>–TiC functionally graded materials. The traveling-zone sintering method permits integrated sintering of materials at variable temperatures. Powder mixtures with TiC contents from 1.8 to 7.0 mole were layered in the same mold and sintered at variable temperatures from 1643 to 1733 K. The synthesized structure was successfully graded, as in the case of individual synthesis of each of the compounds. The hardness of the produced sample showed a tendency to increase with increasing mass fraction of TiC. These results prove that the traveling-zone sintering method has the potential to fabricate functionally graded materials that require variable sintering temperatures.
- Materials transactions
Materials transactions 48(2), 139-142, 2007-02-01