Recently, the number of published papers on the sintering technologies activated by current have increased exponentially. In particular, it has been reported that the application of electric field as high as 120 V/cm permitted the instantaneous full densification of yttria stabilized tetragonal zirconia at the unusual low temperature of 850°C. The mechanisms of the so called flash sintering phenomenon are elucidated by analyzing the temperature distribution of the bulk sample under the application of the electric field.

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A novel, nontraditional route for controlling the morphology of yttria-stabilized zirconia nanopowders is explained. For understanding the real nature of yttrium zirconium oxalate nonisothermal decomposition and for the development of nanosize 3 mol% Y 2 O 3 ⅐97mol% ZrO 2 , mass spectrometry, X-ray, and TEM investigation were used. Characteristics of zirconia crystallization under nonisothermal heating conditions were studied. Morphology evolution during Y-Zr oxalate nonisothermal decomposition was investigated to optimize the heating schedule of calcination. The nonlinear heating regime has been used to produce nanosized Y 2 O 3 -stabilized tetragonal ZrO 2 powder with the finest primary crystallites and narrowest secondary aggregate size distribution.

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Hard boron suboxide (B 6 O) is a difficult-to-consolidate ceramic material that requires extreme processing conditions to achieve sintering activation and is only consolidated readily at high pressures above 4 GPa. In this contribution, for the first time, we report the consolidation of hard and tough laboratory-synthesized B 6 O by the spark-plasma sintering (SPS) technique. The density of SPS-sintered specimens of >= 98% is reported, and an optimal combination of 34 GPa hardness and 4 MPa·m 1/2 fracture toughness is achieved by controlling the amount of glassy phase boron oxide (B 2 O 3 ) with an appropriate SPS set up. The effects of the type of protection used, i.e., graphite die lined only with graphite foil, BN coating, or tantalum foil, on the phase compositions and properties of bulk were studied. Finally, composites of boron suboxide and boron carbide, B 6 OxB 4 C (x = 0, 3, 5, 10, 20, 40 wt %) were fabricated by SPS, and a significant improvement in the mechanical properties was achieved. Results showed that dense B 6 O10 wt %B 4 C composite material with a hardness above 40 GPa and a fracture toughness of 4.8 MPa·m 1/2 were obtained.

Dense boron carbide (above 95%) was achieved through high pressure (300 MPa) and low temperature (1600°C) Spark Plasma Sintering (SPS). This approach resulted in improvement of fracture toughness and of dynamic toughness when compared to corresponding toughness values of the sample sintered by conventional SPS (2100°C, 50 MPa). Dynamic toughness was extracted from Split Hopkinson Pressure Bar measurements. Results are understood based on microstructure and on very different behaviour of the samples in respect to residual B 2 O 3 and carbon available in the raw B 4 C powder.