Effects of carbon nano-additives on characteristics of TiC ceramics prepared by field-assisted sintering

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.

Role of Ti3AlC2 MAX phase on characteristics of in-situ synthesized TiAl intermetallics. Part I: sintering and densification

“…It should be noted that the melting temperature of aluminum is 660 °C but the temperature specified in the diagram, recorded by the thermocouple (an infrared sensor) located outside of the die, is different from the actual temperature inside the die and between the powder particles. Due to instantaneous plasma sparks, the local temperature between the particles in SPS method is much higher than the temperature measured by the thermocouple [34,35]. At 400 °C, the temperature rise slope suddenly increases to the final temperature of 900 °C.…”

On the oxidation behavior of ZrB2–SiC–VC composites

“…The thermodynamics analysis of oxides formed on the surface of the composite is shown in Figure 5. The probable oxidation reactions other than Reaction (7) are given in the following:…”

“…At high‐temperature applications, the devices must be made of a group of materials named ultrahigh‐temperature ceramics (UHTC). These materials are limited to less than 20 items such as ZrB 2 , 1–4 NbC, 5 TiC, 6,7 TaC, 8,9 TiB 2 , 10–12 etc. ZrB 2 ‐based ceramics and composites have a matchless combination of characteristics such as high melting points, high conductivities (thermal and electrical), low tendency to the chemical reactions with molten metals, and outstanding thermal shock resistance 13–15 …”

Insights on Spark Plasma Sintering of Magnesium Composites: A Review

“…SPS of TiB 2 and the ZrB 2 -SiCw-C f system also shows relatively high density while adding nitrates [21,22]. The SPS of the Ti/TiB 2 -based composite allows the formation of in situ phases corresponding to significantly improving mechanical properties [23][24][25][26][27]. These studies show that the SPS process is used for high melting temperature materials, so processing temperature and oxide layer formation have been significantly reduced.…”