Recent advancements in SiC-AlN-TiB2-VC multiphase ceramics have demonstrated unprecedented mechanical properties, with a fracture toughness of 12.5 MPa·m^1/2 and a hardness of 28.7 GPa, achieved through optimized sintering techniques at 1850°C for 2 hours under 50 MPa pressure. These properties are attributed to the synergistic effect of SiC and AlN, which provide high thermal stability, while TiB2 and VC contribute to enhanced grain boundary strengthening. The resulting microstructure exhibits a fine-grained matrix with an average grain size of 0.8 µm, significantly reducing crack propagation paths and improving overall durability.
Thermal conductivity studies reveal that SiC-AlN-TiB2-VC ceramics exhibit exceptional heat dissipation capabilities, with a thermal conductivity of 135 W/m·K at room temperature, making them ideal for high-temperature applications such as aerospace components and nuclear reactors. The incorporation of AlN (thermal conductivity: 320 W/m·K) and SiC (thermal conductivity: 490 W/m·K) ensures efficient heat transfer, while the addition of TiB2 and VC mitigates thermal expansion mismatches, maintaining structural integrity up to 1600°C. This combination results in a coefficient of thermal expansion (CTE) of 4.8 × 10^-6 K^-1, closely matching that of many high-performance alloys.
Electrochemical performance evaluations indicate that SiC-AlN-TiB2-VC ceramics possess remarkable corrosion resistance in harsh environments, with a corrosion rate of only 0.002 mm/year in concentrated sulfuric acid at 80°C. The formation of a protective oxide layer composed primarily of SiO2 and Al2O3 on the surface enhances chemical stability, while the presence of TiB2 and VC reduces interfacial reactions with aggressive media. These properties make these ceramics suitable for use in chemical processing equipment and marine applications where durability is critical.
Recent research has also explored the tribological behavior of SiC-AlN-TiB2-VC ceramics under extreme conditions, revealing a friction coefficient as low as 0.15 against steel counterparts at loads up to 100 N and sliding speeds of 1 m/s. The wear rate was measured at 1.3 × 10^-6 mm^3/N·m, significantly lower than traditional ceramic materials such as Al2O3 or ZrO2. This is attributed to the self-lubricating properties imparted by VC and the high hardness provided by TiB2, which collectively reduce adhesive wear and surface degradation.
Finally, computational modeling using density functional theory (DFT) has provided insights into the atomic-level interactions within SiC-AlN-TiB2-VC ceramics, predicting interfacial bonding energies ranging from -3.5 eV to -5.2 eV between constituent phases. These simulations confirm strong covalent bonding at grain boundaries, which enhances mechanical strength and thermal stability. Experimental validation through transmission electron microscopy (TEM) has corroborated these findings, revealing coherent interfaces with minimal defects, further supporting the material's superior performance in demanding applications.
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