Thermal shock resistance of hot-pressed SiCw/Si3N4(w=whisker) composites was investigated by thermal shock resistance parameters and water quenching test. The results showed that the thermal shock resistance to fracture initiation and crack-stable repropagation deteriorated with increasing SiCw content in spite of the improvement of fracture toughness, K1C. This could be attributed to the great decrease of strength, σand the considerable increase of Young’s modulus, E, and thermal expansion coefficient, α,resulting from the addition of SiC whiskers. The curves of the residual strength, σ,after water quenching versus thermal shock temperature difference, △T, e.g. σ1-△T, showed good relationships with the calculated thermal stress fracture resistance parameter, R, and thermal stress crack stability parameter, Rst. The crack propagation of SiC whisker reinforced Si3N4 occurred primarily in a quasi-static manner, and it could be mainly attributable to SiC whiskers’ pulling-out and bridging toughening effects.

The in situ synthesized TiB reinforced titanium matrix composites have been prepared by spark plasma sintering at 800–1200 ℃ under 20 MPa for 5 min. The effects of sintering temperature and reinforcement volume fraction on flexural strength, Young’s modulus and fracture toughness of the composites are investigated. The titanium matrix consists of α-Ti and β-Ti phases, and the volume fraction of β-Ti increases with increasing sintering temperatures. The in situ synthesized TiB reinforcements are distributed randomly and uniformly in matrix. The transverse section of TiB has a hexagonal shape aligned along [010] direction, and the crystallographic planes of the TiB needles are always of the type (100); (101) and (101). The 10 vol% TiB reinforced composite sintered at 1000 ℃ exhibits excellent mechanical properties. The flexural strength, Young’s modulus and fracture toughness of this composite are 1560 MPa, 137 GPa and 8.64 MPa·1/2, respectively.

A novel sol–gel process has been successfully developed for preparing strontium bismuth tantalite (SrBi2Ta2O9, known as SBT) with ethylene alcohol as a solvent and acetic acid as a catalyst. The size of phase-pure SBT nanoparticles could be 4 nm in diameter by avoiding the formation of the fluorite phase at the low temperatures (550–600◦C). The behavior of the crystallization in SBT is investigated by XRD, TG-DTA, FT-IR and TEM. The nanoparticle size as a function of the annealing temperature is also investigated. By fitting the Arrhenius curve, we obtain the crystalline and vitreous growth activation energies, i.e, Ea1 = 0.709 eV and Ea2 = 0.093 eV. The two other fitting parameters, transition temperature T0 = 814 K (541◦C) and transition width △= 0.022, directly show the behavior of the phase transition from vitreous phase to crystalline phase.

Silicon nitride (Si3N4) ceramics incorporated various amount of titanium diboride (TiB2) were fabricated by hot pressing at 1800℃ for 1 h. The influence of TiB2 on the microstructure and mechanical properties of Si3N4 ceramic was investigated. When a small amount of TiB2 (2vol.%) was added, the mechanical properties of Si3N4 were improved significantly, whereas they began to degrade when more TiB2 (＞4vol.%) was introduced. The reaction between TiB2 and Si3N4 matrix is responsible for the variation in mechanical properties of the TiB2/Si3N4 composites.

LiTaO3/Al2O3 ceramic composites were fabricated by hot pressing and pressureless sintering, respectively, to investigate the effect of piezoelectric secondary phase on the properties of structural ceramics. Phase constitution, microstructure and mechanical properties of the ceramic composites were studied. LiTaO3 could stably coexist with Al2O3 during sintering. LiTaO3 phase was located at the grain boundaries of Al2O3 matrix fabricated by different processing routes. Domain structures were clearly seen in LiTaO3, confirming that LiTaO3 remained hexagonal ferroelectric phase. About 5 vol.%LiTaO3/Al2O3 ceramic composite prepared by pressureless sintering at 1300 ℃ showed an increase in fracture toughness. Energy dissipation due to domain switching was suggested as a toughening mechanism. With the increasing of LiTaO3 content, the domain switching toughening mechanism was decompensated by the decreased relative density of LiTaO3/Al2O3 ceramic composites. For LiTaO3/Al2O3 ceramic composites prepared by hot pressing at 1500 ℃, the bending strength decreased because of the increased grain size of Al2O3 matrix. The toughening effect due to domain switching was also decompensated by the coarsening of Al2O3 matrix grains, the weaker net-like LiTaO3 phase and the weaker bonding strength between LiTaO3 phase and Al2O3 matrix.