Influence of Nanodispersed Metal Oxide Additives on the Sintering of Al2O3 Nanopowder and the Properties of the Resulting Composites

The creation of structural and functional materials based on corundum ceramics with high physical and mechanical properties is an urgent task of modern science and technology. In this regard, new methods for producing ceramics are being searched for, including those using nanodispersed components. In this work, the effect of modifying additives obtained by electric explosion of wires in a mixture of Ar and O2 on characteristics of sintered Al2O3 nanopowder was assessed for the first time. The conducted complex of studies showed that the introduction of 3 vol. % modifying additives in the form of CuO, TiO2, Fe2O3 nanopowders and compositions based on them significantly increases the relative density of the sintered compact. This is attributed to the lower homologous temperature of the modifiers relative to the matrix and to the formation of novel, less refractory ionic compounds. It was found that differences in the coefficients of thermal expansion of the matrix and modifying oxides lead to relaxation, or a noticeable increase in the second-order stresses in the matrix. At the same time, the observed strengthening of the sintered composites, compared to unmodified Al2O3, is apparently due to the increased relative density rather than to residual compressive stresses that have a dissipative effect on cracks propagating in the ceramics.