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Sintering of pure B4C requires extremely high temperatures of more than 1800 °C, even with techniques such as spark plasma sintering (SPS). In this study, sintering of B4C was achieved at low temperature using reactive Ti–B mixture as a sintering additive. Ti and B powders (1:2 atom ratio) were milled for 8 h and added to B4C powder in proportions of 5, 10, and 20 wt% and milled for 4 h to achieve good dispersion. Dense B4C composite compacts were obtained using SPS at 1400 °C. A pore free microstructure consisting of B4C grains surrounded with fine grains of (Ti0·9W0.1)B2 and W2B5 was obtained due to WC contamination. The activation energy for sintering reduced from 234 to 155 kJ/mol with the increase in the amount of Ti–B mixture from 5 to 20 wt%. The B4C composite with 5 wt% Ti–B mixture had the maximum hardness of 3225 ± 218 H V.

Simultaneous synthesis and densification of boron carbide and boron carbide- graphene nano platelets (GNP) were carried out by reactive spark plasma sintering of amorphous boron and graphene nano platelets at temperature ranging from 1200 to 1600 °C, pressure of 50 MPa and heating rate of 50 °C/min and 100 °C/min. X-ray diffraction and Raman spectroscopy confirmed the formation of required phases. Electron microscopic images revealed the formation of sub-micron and nano sized grains of plate like morphology. Sintered product with high relative density of 96%TD was achieved at a temperature of 1600 °C and heating rate of 50 °C/min for B4C stoichiometric composition and also exhibited maximum hardness of 21.10 GPa.

In this study, Titania (TiO 2 ) based composites reinforced with 2 wt% of various carbon nanomaterials were prepared using spark plasma sintering (SPS). Prior to SPS, the samples were ball milled. The reinforcements used in the composites were graphene nanoplatelets (GNP), carbon nanotubes (CNT) and single walled carbon nanohorns (SWNH). The ball milled powders and SPS compacts were characterized using various techniques. Mechanical and photocatalytic properties of the SPS composites were evaluated and compared for different nano-carbon reinforced TiO 2 composites. X-ray diffraction and Raman spectroscopy studies confirmed that the milled powders comprised of Anatase phase which transformed into Rutile phase during SPS. Nano transformation twins were observed in Rutile grains. Fractured surfaces showed that the reinforcements were well bonded with the TiO 2 grains and the SWNH reinforcement resulted in comparatively finer grain size. Nanoindentation studies showed that the hardness and elastic modulus of GNP reinforced composites was 78% and 30% respectively higher compared to TiO 2 matrix. The hardness and modulus of the CNT reinforced TiO 2 increased by 22% and 5.4% respectively while that of the SWNH reinforced TiO 2 increased by 11% and 23% respectively. GNP and CNT reinforced TiO 2 exhibited superior photocatalytic activity for the degradation of methylene blue dye compared to pure TiO 2 .