Title : ZrB2-SiC, ZrB2-SiC-ZrC and TaB2-SiC Composites Manufactured Under High 4 GPa and 30 MPa Pressures
Comparison of structures (studied by X-ray with Rietveld refinement and SEM EDX) and Vickers hardness, Hv, (under 9.8 N-load) of ZrB2 - (20, 30 wt.%) SiC, ZrB2 - 20 wt.% SiC - (5, 10, 15 wt.%) ZrC, and TaB2 - (20, 30 wt.%) SiC composites consolidated at 30 MPa by hot pressing (HotP) and at 4 GPa quasihydrostatic pressure (HP) under high temperatures (1800-1900?C) with that of consolidated pure ZrB2 under similar conditions were performed. The addition of SiC to ZrB2 and HotP at 30 MPa and 1900 oC leads to the increase of hardness from 13 GPa for pure ZrB2 to 23 GPa and 29,4 GPa if 20 and 30 wt% of SiC was added, respectively. Pressure increase up to 4 GPa allowed decreasing sintering temperature to 1800 oC and attaining higher - 17.7 GPa hardness for pure ZrB2 and similar - 24 GPa hardness if 20 wt.% of SiC was added. HotP at 1800 oC and addition of 15 wt.% ZrC to ZrB2-20 wt/%SiC composition allowed to get HV=15.9 GPa only. HotP at 30 MPa and 1900 oC allowed attaining 29.7 GPa and 34.4 GPa hardness if 20 and 30 wt.% of SiC, respectively, was added to TaB2. While HP at 4 GPa and 1800 oC allowed attaining only 23,5 and 26 GPa, respectively. Despite the hardness of the prepared ZrB2-based composites increased in comparison to pure ZrB2, they demonstrated lower heating resistance and lower melting temperatures. The work is supported by Projects NATO SPS G5773; 03-03-20, ISM-29/20, III-3-20 (0779), of NASU.
What will audience learn from your presentation
- The audience will learn that the application of a high pressure of 4 GPa can lead to a significant reduction in sintering temperature compared to sintering at a moderate pressure of 30 MPa and achieve similar or better mechanical performance of composites. The established correlations between manufacturing conditions, structures and characteristics of the materials are useful from a fundamental and practical point of view.
- The refractory boride-based composites are promising for application in hypersonic aerospace and atmospheric re-entry vehicles, cutting tools, metallurgy, microelectronics and refractory industries in general. The development of new materials with improved functional characteristics allows progress in these areas.