Abstract
Five carbonaceous nano-additives (graphite, graphene, carbon black, carbon nanotubes, and diamond) had different impacts on the sinterability, microstructural evolution, and properties of titanium carbide. In this research, the sintering by spark plasma was employed to produce the monolithic TiC and carbon-doped ceramics under the sintering parameters of 1900 ºC, 10 min, 40 MPa. The carbon black additive had the best performance in densifying the TiC, thanks to its fine particle size, as well as its high chemical reactivity with TiO2 surface oxide. By contrast, the incorporation of nano-diamonds resulted in a considerable decline in the relative density of TiC owing to the graphitization phenomenon, together with the gas production at high temperatures. Although carbon precipitation from the TiC matrix occurred in all samples, some of the added carbonaceous phases promoted this phenomenon, while the others hindered it to some extent. Amongst the introduced additives, carbon black had the most contribution to grain refining, so that a roughly halved average grain size was attained in comparison with the undoped specimen. The highest values of hardness (3233 HV0.1 kg), thermal conductivity (25.1 W/mK), and flexural strength (658 MPa) secured for the ceramic incorporated by 5 wt% nano carbon black.
Highlights
As a well-known ultra-high-temperature ceramic (UHTC), titanium carbide (TiC) has a wide range of physical and mechanical characteristics, e.g., low neutron absorption cross-section, excellent hardness, high thermal resistivity, superior melting point (3160 °C), high chemical stability, and low density [1,2,3,4]
The monolithic TiC arrived at a relative density of > 95%, which was an acceptable value for a sintering aid-free TiC ceramic
The influence of various carbonaceous phases on the microstructural evolution, mechanical-physical properties, and sinterability of TiC was examined in this research
Summary
As a well-known ultra-high-temperature ceramic (UHTC), titanium carbide (TiC) has a wide range of physical and mechanical characteristics, e.g., low neutron absorption cross-section, excellent hardness, high thermal resistivity, superior melting point (3160 °C), high chemical stability, and low density [1,2,3,4]. Nguyen et al studied the TiCdiamond system sintered by the SPS method This additive worsened all relative density, bending strength and hardness of titanium carbide, its influence on the thermal conductivity of titanium carbide was remarked. The diamond additive could improve the thermal conductivity of titanium carbide by almost 30%, standing next to 23 W/mK This comparative research intends to compare the effect of different carbonaceous compounds, i.e., graphite, graphene, carbon black, carbon nanotubes (CNTs), and nano-diamonds, on the microstructure, physical-mechanical features, and sinterability of titanium carbide. The thermal conductivity, relative density, bending strength, and Vickers hardness of all specimens were measured/calculated, comparing to each other
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