The TiB 2 -Cu cermets with predominant concentration of superhard TiB 2 (from 45 to 90vol.%) were fabricated using elemental powders by means of SHS (self-propagating hightemperature synthesis) process and simultaneously densified by p-HIP (pseudo-isostatic pressing technique). The heat released during highly exothermic SHS reaction was "in situ" utilized for sintering. The combustion occurred even for 50vol.% Cu dilution. According to XRD metallic copper binder was formed in those cermets in whole range of investigated compositions. The TiB 2 volume fraction significantly influenced the properties of fabricated materials, especially grain size and hardness. Both the average grain size and hardness significantly increased with TiB 2 content, so the maximum value of 18GPa was measured for TiB 2 -5vol.%Cu composite. Coarse grains of 6.4µm in size were observed for this composite while TiB 2-based submicro-composites were formed for 40-50% of Cu where the average grain size did not exceed 0.6µm. The Vickers hardness of 16-18 GPa obtained for cermets containing from 85 to 90vol.% of TiB 2 and no radial cracks in Vickers hardness test proved that in term of hardness and fracture toughness the composites might be competitive to WCCo cermets.

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TiB2-based ceramic matrix composites (CMCs) were fabricated using elemental powders of Ti, B and C. The self-propagating high temperature synthesis (SHS) was carried out for the highly exothermic “in situ” reaction of TiB2 formation and the “tailing” synthesis of boron carbide characterized by weak exothermicity. Two series of samples were fabricated, one of them being prepared with additional milling of raw materials. The effects of TiB2 vol fraction as well as grain size of reactant were investigated. The results revealed that combustion was not successful for a TiB2:B4C molar ratio of 0.96, which corresponds to 40 vol% of TiB2 in the composite, however the SHS reaction was initiated and self-propagated for the intended TiB2:B4C molar ratio of 2.16 or above. Finally B13C2 was formed as the matrix phase in each composite. Significant importance of the grain size of the C precursor with regard to the reaction completeness, which affected the microstructure homogeneity and hardness of investigated composites, was proved in this study. The grain size of Ti powder did not influence the microstructure of TiB2 grains. The best properties (HV = 25.5 GPa, average grain size of 9 μm and homogenous microstructure), were obtained for material containing 80 vol% of TiB2, fabricated using a graphite precursor of 2 μm.

TiB2-based cermets with various Co contents were fabricated from elemental powders "in situ" by means of the Self-propagating High-temperature Synthesis, SHS, and Pseudo-Hot Isostatic Pressing, P-HIP method. The sample pressed into a cylindrical compact was ignited in a steel can by an external heating element coiling the can. After SHS initiation, which was detected by rapid temperature increase, the samples were quickly pressed pseudo-isostatically under a pressure of 192 MPa and held for 5 min. Samples with predominant concentration of TiB2, which varied from 70 to 85 vol.% with the addition of 5 vol% of Ti, were investigated in this study. Appreciable differences in terms of microstructure, density and hardness were observed depending on the composition. The average TiB2 grain size increased while porosity decreased with rising concentration of TiB2. The material synthesized with increased to 85% concentration of superhard TiB2 grains and minimized concentration of Co exhibited greatest densification, highest hardness of about 2 400 HV, and the most homogenous microstructure. The reaction mechanism was reportedly proposed, based on temperature monitoring during combustion and previously reported references.