For attaining high-strain-rate superplasticity (HSRS) in ceramic materials, prerequisites are described on the basis of existing knowledge about high-temperature plastic deformation and intergranular cavitation mechanisms. The knowledge suggests that a combination of grain-size refinement to 100-200 nm or smaller and enhanced diffusion caused by doping may highly enhance stress-relaxation around triple junctions and may lead to HSRS at temperatures lower than 1250-1300°C in structural ceramics. From this point of view, recent studies are reviewed and discussed on ceramic superplasticity at strain rates higher than 1 × 10⁻² s⁻¹. Attention is also placed on the fabrication of materials with nanosized grains and the resultant superplastic properties.

Electric field-assisted sintering, in which mechanical pressure is often combined with DC or AC electric field to enhance densification of ceramics and ceramic composites, is gaining interest in recent decades due to the accelerated consolidation compared to conventional, pressureless sintering. In particular, flash sintering, where densification occurs almost immediately (typically < 5 seconds) under a threshold condition of temperature and applied DC electric field, has attracted extensive attention as an innovative sintering method since 2010. It is advantageous that the configuration of apparatus for flash sintering is rather simple in comparison to usual electric field-assisted sintering methods. The flash sintering has been demonstrated in various oxide/non-oxide ceramics, and mechanism of such a dynamic phenomenon has been investigated. The flash sintering event is characterized by an abrupt densification at relatively low temperature and a nonlinear increase in electric conductivity at the occurrence of the flash sintering. Joule heating therefore plays a key role in the flash event. In the present paper, typical examples of flash sintering and advantages of the novel technique are briefly summarized, and recent results of creating new materials and microstructures are introduced.

In order to develop a novel high-speed forming method of carbon fiber reinforced plastic (CFRP) using microwave-irradiation, the heating condition of CFRP was investigated using mullite dense compact with low thermal effusivity (3.8 kJ/m²·s^1/2·K) and alumina dense compact with high thermal effusivity (10.3 kJ/m²·s^1/2·K) as a mold. It was found that mullite dense compact with low thermal effusivity was useful as a mold material for the novel high-speed forming method of CFRP using microwave-irradiation because the mullite dense compact could heat CFRP 1.25 times faster than the alumina dense compact. Furthermore, it was found that the thermal conductivity of the densified mullite compact was affected by the size of the sintered grains, and the densified mullite compact was a mold material having heat resistance and mechanical strength for CFRP molding conditions.

Dense B₄C/TiB₂ composite ceramics have been fabricated from the amorphous B and C, and fine TiC powders (25 nm in size P_s), using pulsed electric current pressure sintering (PECPS) at 2173 K under 50 MPa for 6.0 × 10² s in a vacuum. During PECPS the solid-state reaction between B and C was induced around 1373 K and almost at the same time TiB₂ phase was gradually formed, followed by a continuous formation of B₄C matrix including TiB₂ particles. On the other hand as the reference, two kinds of B₄C/TiB₂ composites from the B/C mixtures and TiB₂ powders (1.86 μm and 58 nm in P_s) were also fabricated as the same manner. The former composites using TiC showed high relative density ≥ 98.9% up to 11 vol% TiB₂ and improved mechanical properties, such as three-point bending strength σ_b of 650 MPa, Vickers hardness H_v of 33.5 GPa and fracture toughness K_IC around 5.45 MPa·m^1/2 at the composition of B₄C/TiB₂ = 93/7 vol%, however, the latter composites revealed lower relative densities of 96.5% at 7 vol%TiB₂ composition and deteriorated mechanical behaviors as P_s of TiB₂ increased.

Highly transparent hydroxyapatite ceramics were fabricated by using the electrically conductive SiC mold during spark plasma sintering. Compared to the conventional graphite mold, the SiC mold lowered the sintering temperature by 50°C at least. The in-line transmission of the sintered ceramics is 82% at a wavelength of 600 nm. The high transmission is a result of fine and dense microstructures. The light scattering behavior was examined to show the Rayleigh and Mie scattering at low and high wavelengths, respectively. The appearance of the Rayleigh scattering, which is caused by nano-sized pores, indicates that the Mie scattering by anisotropic grains was sufficiently suppressed by the fine microstructures.

Ti₃SiC₂ is a typical M_n+1AX_n (MAX) phase ceramics and shows unique metallic-like and ceramic-like properties. To improve these properties, texturing and Al₂O₃ addition have been conducted. The commercial Ti₃SiC₂ powder used contains approximately 10 wt% TiC phase. Textured Ti₃SiC₂ was prepared by slip cast in strong magnetic fields followed by spark plasma sintering (SPS) at 1350°C under 40 MPa for 5 min. The Lotgering orientation factor of (00l) peaks of Ti₃SiC₂ with magnetic field (MF) was 0.96, and relative density of samples was beyond 99%. The bending strength and fracture toughness of Ti₃SiC₂ were improved by texturing. Ti₃SiC₂ with magnetic field showed excellent value of bending strength of 978 MPa, but Al₂O₃ addition caused deterioration of bending strength and fracture toughness. Ti₃SiC₂ with MF showed the plastic deformation at temperature at around 900°C.

In this study, we report that the deposition rate of films is indicated to be strongly related to the preheating conditions of source powder mixture of ZrO2 and NiO. A stable luminescence was observed clearly during film fabrication. In an aerosol gas deposition method, the source powder is charged during transport by the mutual friction of particles and their collision against the inner surfaces of the tubing and nozzle. The charged powder contributes to the deposition rate of film synthesis and the generation of static electricity depends on the surface condition of the source powder. In particular, the amounts of gas and moisture adsorbed on the particle surface might be key factors.