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The research results conducted on binderless tungsten carbide (WC) ceramics obtained by Spark Plasma Sintering (SPS) of WC powders with different average particle sizes (0.095, 0.8, 3 μm) are presented. Nonuniform distribution of crystalline phases and microstructure of the WC ceramics was studied using layer-by-layer XRD analysis and SEM. Surface layers of the WC-based ceramics are characterized by nonuniform distribution of W2C crystalline phase and grain sizes, including the appearance of abnormally large grains. Thickness of the nonuniform layer was at least 50 μm. The effect under study is associated with an intense carbon diffusion from graphite foil. On the one hand, this contributed to a decrease in the intensity of W2C phase particle formation, which is transformed into α-WC phase due to the carbon. On the other hand, it caused abnormal grain growth in the layer where the carbon diffused. The obtained value of the carbon diffusion depth exceeds the values known from the literature (up to 1 μm in the case of volume diffusion even at temperature of 2370℃ and exposure time of ~ 60 h). The use of boron nitride (BN) as a protective coating on graphite mold parts did not prevent the formation of nonuniform layer on the ceramic surface.

A glycine-nitrate self-propagating high-temperature synthesis (SHS) was developed to produce composite MgO-Gd2O3 nanopowders. The X-ray powder diffraction (XRD) analysis confirmed the SHS-product consists of cubic MgO and Gd2O3 phases with nanometer crystallite size and retains this structure after annealing at temperatures up to 1200 °C. Near full dense high IR-transparent composite ceramics were fabricated by spark plasma sintering (SPS) at 1140 °C and 60 MPa. The in-line transmittance of 1 mm thick MgO-Gd2O3 ceramics exceeded 70% in the range of 4–5 mm and reached a maximum of 77% at a wavelength of 5.3 mm. The measured microhardness HV0.5 of the MgO-Gd2O3 ceramics is 9.5±0.4 GPa, while the fracture toughness (KIC) amounted to 2.0±0.5 MPa·m1/2. These characteristics demonstrate that obtained composite MgO-Gd2O3 ceramic is a promising material for protective infra-red (IR) windows.

The research results of the microstructure and corrosion resistance of Ti and Ti-Al-V Russian industrial titanium alloys obtained by spark plasma sintering (SPS) are described. Investigations of the microstructure, phase composition, hardness, tensile strength, electrochemical corrosion resistance and hot salt corrosion of Ti-Al-V titanium alloy specimens were carried out. It was shown that the alloy specimens have a uniform highly dense microstructure and high hardness values. The studied alloys also have high resistance to electrochemical corrosion during tests in acidic aqueous solution causing the intergranular corrosion as well as high resistance to the hot salt corrosion. The assumption that the high hardness of the alloys as well as the differences in the corrosion resistance of the central and lateral parts of the specimens are due to the diffusion of carbon from the graphite mold into the specimen surface was suggested.

Transparent ceramics based on ytterbium oxide have been successfully produced by vacuum sintering of self-propagating high-temperature synthesized powders with use of a La2O3 sintering aid. Phase composition and microstructure of the initial powders were studied by X-ray diffraction analysis and scanning electron microscopy. It was found that addition of 5 mol.% of La2O3 does not cause formation of secondary phases in the Yb2O3 powders. The 4% La:Yb2O3 ceramics showed the best in-line transmittance of 73% at a wavelength of 2 μm among the studied samples. Dependence of the Verdet constant on wavelength was investigated in the range of 0.4–2 μm. The most promising finding is use of the obtained material as Faraday isolators in the wavelength region of ~1.5 μm, where there are no absorption bands, and the Verdet constant is 8.6 rad/(T*m).

Parameters of powder WC + 10% Co sintering modes that exclude the possibility of η-phase (Co3W3C) formation were determined. The phase composition was controlled by introducing colloidal graphite into the original powder.