The simultaneous synthesis and densification of dense TiC–TiB2 composite has been investigated starting from Ti, B4C, and C as reactants, and using the spark plasma sintering (SPS) technique. The optimal conditions for complete conversion of the reactants to the composite were determined for different applied DC current levels. A kinetic investigation performed allows us to conclude that solid-state diffusion is the mechanism governing the synthesis process. It is seen that TiC is the first phase formed, while TiB2 formation occurs afterward. Two intermediate boride phases, i.e. TiB and Ti3B4, are also formed but, as the SPS holding time was augmented, they were gradually and completely converted to TiB2.Moreover, it is found that in order to reach relatively high dense products, an electric current needs to be applied for time intervals longer than those required for obtaining complete conversion. A pure dense product (relative density B98%) was obtained when an electric pulsed current of 1100 A and a mechanical pressure of 20 MPa were applied for about 4 min.
Simultaneous spark plasma synthesis and densification of TiC-TiB2 composites
LOCCI, ANTONIO MARIO;ORRU', ROBERTO;CAO, GIACOMO;
2006-01-01
Abstract
The simultaneous synthesis and densification of dense TiC–TiB2 composite has been investigated starting from Ti, B4C, and C as reactants, and using the spark plasma sintering (SPS) technique. The optimal conditions for complete conversion of the reactants to the composite were determined for different applied DC current levels. A kinetic investigation performed allows us to conclude that solid-state diffusion is the mechanism governing the synthesis process. It is seen that TiC is the first phase formed, while TiB2 formation occurs afterward. Two intermediate boride phases, i.e. TiB and Ti3B4, are also formed but, as the SPS holding time was augmented, they were gradually and completely converted to TiB2.Moreover, it is found that in order to reach relatively high dense products, an electric current needs to be applied for time intervals longer than those required for obtaining complete conversion. A pure dense product (relative density B98%) was obtained when an electric pulsed current of 1100 A and a mechanical pressure of 20 MPa were applied for about 4 min.
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