Composite materials based on Al2O3‒SiC‒TiB2 obtained by SHS extrusion and their hightemperature annealing

As a result of the combination of the processes of selfpropagating high-temperature synthesis (SHS) and shear high-temperature deformation, realized in the method of SHS-extrusion, ceramic rods based on Al2O3‒SiC‒TiB2 were obtained. The influence of technological parameters of the process (delay time, pressing pressure) on the length of the obtained rods has been studied. The obtained materials were annealed in the range 1000‒1300 °C, and the microstructure and phase composition of the materials were studied before and after heat treatment.

Preparation by SHS-extrusion method of compact ceramic materials based on the Ti‒B system, modified with nanosized Si3N4 particles

Compact ceramic materials based on the Ti‒B system modified with 5 wt. % of nanosized Si3N4 particles. The results of studies of the structure, phase composition, and physical and mechanical characteristics of the materials obtained are presented. It is shown that the addition of Si3N4 promotes the formation of new phases, in particular, titanium diboride and nitride in the final product. It was found that the introduction of modifying nanosized Si3N4 particles into the initial charge leads to an increase in hardness and microhardness by 15‒20 %, as well as to an increase in crack resistance by 1,5 times in comparison with unmodified samples.

The effect of gas atmosphere on the coating formation by electric arc surfacing with cermet SHS electrodes of the TiB2–Co2B composition

Due to their unique properties, metal-matrix composite materials, when used as a surfacing material for electric arc surfacing, provide high properties of the deposited layers. SHS-extrusion is a promising method for a wide range of surfacing metal-matrix electrodes. The gas environment of surfacing affects the quality of coatings formed by SHS electrodes, their microstructure and properties. In this paper, cermet SHS electrodes of the TiB2–Co2B composition obtained by SHS-extrusion were used to form protective coatings on a steel substrate by electric arc surfacing in an argon atmosphere and in a nitrogen atmosphere. The elemental and phase composition, as well as the microstructure of the deposited layers, were investigated. Based on the conducted studies, the influence of the gas atmosphere on the formation of the structure of cermet coatings was established. It is shown that, despite the similar phase composition, there are fundamental differences in the microstructures of the deposited coatings, which are caused by the partial fusion of the tungsten electrode and the transfer of the electrode material in the coating during surfacing in an argon atmosphere. The maximum values of the microhardness of coatings deposited in a nitrogen atmosphere exceed the maximum microhardness of coatings obtained by surfacing in an argon atmosphere by 200–450 HV.

Extraction of compact ceramic electrode materials based on the Ti‒B‒Fe system modified by nanosized AlN particles by SHS extrusion

Compact ceramic electrode materials based on the Ti‒B‒Fe system modified with nanosized particles of aluminum nitride (up to 15 wt. %) were obtained by SHS extrusion. The effect of additives on the combustion characteristics of the studied system, as well as on the structure and phase composition of the obtained materials, is studied. The addition of aluminum nitride increases the content of boride and nitride phases in the final product. It was found that the introduction of modifying nanosized particles of aluminum nitride into the initial charge leads to the grinding of grains of boride and nitride phases, which together increases the microhardness by 10 %, in comparison with unmodified samples.