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Link for citation: Nikitin D.S., Shanenkov I.I., Nassyrbayev A., Vympina Yu. N., Orlova E.G., Ivashutenko A.S., Sivkov A.A. Obtaining bulk products from Cu-SiC metal-matrix composite for energy-efficient heat-conducting systems. Bulletin of the Tomsk Polytechnic University. Geo Аssets Engineering, 2023, vol. 334, no. 7, рр. 93-101. In Rus. The relevance of the research is associated with the rapid development of modern high-performance computing systems, superneurocomputers and artificial intelligence devices. Today such development is held back largely due to the lack of an effective cooling system for high-power elements of their structures. Composite materials Cu-SiC with improved physical, mechanical and thermophysical characteristics can be used to solve problems of heat removal intensification. The main aim of the research is to obtain bulk products from metal-matrix composite Cu-10% SiC with improved physical, mechanical and thermal characteristics by spark plasma sintering. Objects of the research are bulk products from metal-matrix composite Cu-10%SiC. The samples were obtained by spark plasma sintering at temperatures of 700, 750, 800, 850 °C and a pressure of 60 MPa. Methods: spark plasma sintering, X-ray diffractometry (X-ray phase analysis), scanning electron microscopy, indentation, laser flash method. Results. Experimental studies have been carried out to obtain bulk metal-matrix composites with a copper matrix and the addition of reinforcing superhard particles of silicon carbide Cu-10%SiC. The compaction of dispersed composite materials was carried out by spark plasma sintering at various temperatures of 700, 750, 800, and 850 °C. The microstructure and composition of initial dispersed materials and final bulk products have been studied. It is shown that the spark plasma sintering method has advantages for obtaining relatively dense materials with high physical, mechanical and thermal properties. Analysis of the obtained samples showed the formation of a dense (up to ~88 %) homogeneous fine-grained composite structure. The greatest densification of the material is achieved at the highest sintering temperature of 850 °C, which causes this sample to demonstrate the maximum hardness (H=3,63 GPa) and Young's modulus (E=159,63 GPa), as well as the thermal conductivity at room temperature (λ=223 W/m K). The obtained composite materials can be used as structural and functional materials for energy-efficient heat-conducting systems.

The work relevance is caused by the need to study the changes of biomass thermophysical characteristics in its thermal transformation in relation to the design of technological equipment and energy use. The main aim of the research is to study the thermophysical characteristics during slow pyrolysis of biomass with different mineralization amount. Objects: biomass resources with different amount of mineralization ­– straw (Ad=2,8 %), nonconforming wheat bran (Ad=6,9 %), lowland peat of the Sukhovsky deposit (Ad=22,8 %). Methods. Thermotechnical characteristics of biomass samples and their carbon residue are determined according to certified methods (GOST R 54186-2010 (EN 14774-1: 2009), GOST R 56881-2016 (E1755-01), GOST 11305-2013, 11306-2013, GOST 32990-2014 (EN 15148: 2009)); values of the calorific value were determined using the ABK-1 calorimeter (RET, Russia) in accordance with GOST 147-2013 (ISO 1928-2009); elemental analysis of organic part was carried out on a Vario Micro Cube (Elementar, Germany) device; thermal processing was carried out by differential thermal analysis and physical experiment; the thermophysical characteristics of the biomass and its carbon residue were measured by laser flash method using the thermal conductivity analyzer Discovery Laser Flash 1 (DLF-1); the true density was measured using an automatic gas pycnometer Ultrapyc-1200e (Quantachrome Instruments, USA); the carbon residue structure was studied by scanning microscopy VEGA 3 SBU electron microscope (TESCAN, Czech Republic). Results. Straw and bran pyrolysis proceeds in two stages, differing in the average rate of decomposition – (0,38…0,41) %·°C–1 and 0,09 %·°C–1 respectively. Peat decomposition occurs in the whole temperature range (220–500 °C) with an average decomposition rate of 0,11 %·°C–1. It was found that the thermal conductivity of carbon residue from straw and bran, which have a relatively low ash content for biomass, does not significantly change up to 400 °C, after which this value increases. The heat capacity of these samples increases with the temperature of their production to 300 °C, after which it sharply decreases. The carbon residue obtained at 500 °C has a higher heat capacity value compared to the residue obtained at 400 °C. These changes can be explained by decomposition of biomass organic part components – cellulose and lignin. The heat capacity and the thermal conductivity of sukhovsky peat carbon balance, have a high mineralization amount (Ad=22,8 %), decrease in all temperature range, due to the inorganic components share increase in result of organic part decomposition, which is confirmed by the solid phase density increase.