The microstructure and phase composition of the high-content Al2O3-Y2O3-doped spark plasma-sintered silicon nitride were investigated. Fully dense silicon nitride ceramics with a typical α-Si3N4 equiaxed structure with average grain size from 200 to 530 nm, high elastic modulus of 288 GPa, and high hardness of 2038 HV were spark plasma sintered (SPSed) at 1550 °C. Silicon nitride with elongated β-Si3N4 grains, higher hardness of 1800 HV, density of 3.25 g/cm3, and Young’s modulus 300 GPa SPSed at 1650 °C was also reviewed.

Silicon nitride based ceramics with aluminum, yttrium and magnesium oxides were produced by cold isostatic pressing and free sintering. The phase composition of the starting MgO powder obtained by the novel technology has been studied. The effect of magnesium oxide content on the structure of the produced materials has been investigated. It was found, that obtained materials with 1 and 2wt.% of magnesium oxide and without it have a typical β-silicon nitride structure with elongated grains. Ceramics with 5wt.% magnesia has a duplex α/β-structure with elongated and equiaxed grains. Ceramics with 2wt.% magnesium oxide has a maximum density of 2.91g/cm3. The increases in magnesium oxide content upto 5% led to decrease in the shrinkage (from 16% to 12%) and density (from 2.88 to 2.37g/cm3)

In this work, dense zircon-based ceramic coatings were obtained from inexpensive zircon powder on a steel substrate by using a new multi-chamber gas-dynamic accelerator. The microstructure and phase composition of the coating were characterized by scanning electron microscopy, optical microscopy, and X-ray diffraction. The mechanical properties of the coatings were evaluated using microindentation, wear tests and bonding strength tests. The results showed that the obtained zircon-based ceramic coatings were continuous without cracks and bonded well with substrate without a sublayer. The zircon-based ceramic coatings consisted of c-ZrO₂ (major phase), m-ZrO₂ and SiO₂. The zircon-based ceramic coatings had a porosity of 0.1%, hardness of 526 ± 65 HV_0.2, and a fracture toughness of 2.5 ± 0.6 (МPа∙m^1/2). The coatings showed the low specific wear rate and average erosion rate. The failure mode occurring in the tested coatings was cohesive.

Composite ZrB₂–MoSi₂ coating modified by Y₂O₃ and Al was prepared by a new multi-chamber detonation accelerator (MCDS) on carbon/carbon composites. Postdeposition heat treatment of the samples at 1500 °C for 1 and 6 h was carried out in air. The effect of heat treatment on the microstructure and phase composition of the ZrB₂–MoSi₂ coating was investigated by scanning electron microscopy and X-ray diffraction phase analysis. The as-sprayed coating presented as a dense lamellar structure, composed of m-ZrO₂, t-ZrO₂, some hexagonal ZrB₂, and cubic Al phases. The m-ZrO₂, c-ZrO₂, and h-(α-Al₂O₃) formed at 1500 °C. The coatings after heat treatment (1 and 6 h) exhibited a structure without cracks. The porosity (~1%) of the coating did not change after heat treatment. Thin, continuous, silica-rich film covered the surfaces of ZrO₂ and Al₂O₃ particles, and could have played a role during heat treatment by acting as a grain lubricant for particle rearrangement.