RESEARCH OF STRUCTURE AND PHYSICAL AND MECHANICAL PROPERTIES OF CERAMICS BASED ON ALUMINUM AND ZIRCONIUM OXYNITRIDES

Abstract

Relevance. The development of geology in the XXI century is impossible without solving the fundamental problems of modern materials science, caused by the tasks of creating new materials for functional purposes. Despite the variety of methods for aluminum and zirconium oxynitride synthesis and consolidating ceramic based on them, currently being developed, scientific and practical interest is the solid phase synthesis during compaction of corresponding mixtures in inert atmosphere. In this case, powders can be pressed into compacts, both before and during sintering. In the latter case various variants of hot pressing and spark plasma sintering can be applied. For refractory ionic-covalent transition metal oxynitrides, the activated sintering is an urgent problem, since it is carried out by a diffusion mechanism. To solve this problem, it is necessary to study the patterns and mechanisms of consolidation of oxynitride ceramic materials and to search for appropriate activating additives and activation methods. The main aim of the research is to develop a method for obtaining high-density durable ceramics based on aluminum and zirconium oxynitride, including the synthesis of combustion of powder mixtures followed by hot pressing in inert atmosphere and to investigate the structure and physico-mechanical properties of the resulting compacts. The methods: sieve analysis of coarse powders using the A20 analyzer, X-ray phase analysis of the samples under study, hydrostatic weighing to determine the apparent density of sintered samples, measurement of the microhardness of sintered samples, scanning electron microscopy, scratch testing. The results. Using a unique method, including the synthesis of Al2O3-AlN powder by burning Al nanopowder and subsequent hot pressing in inert atmosphere, an oxynitride ceramic based on aluminum oxynitride was obtained. The resulting ceramics had the following physical and mechanical properties: modulus of elasticity during indentation EIT=286537 MPa, indentation hardness HIT=13160 MPa, specimen strength σs=2912 MPa. The ultra-high solid oxynitride ceramic ZrO2-ZrN (modulus of elasticity during indentation EIT=323897 MPa, indentation hardness HIT=19244 MPa, specimen strength σs=3381 MPa) was obtained by hot pressing. The obtained materials are proposed for use in the technology of new generation functional ceramics.

Keywords

• aluminum nanopowder
• zirconium dioxide
• aluminum oxynitride
• ceramics
• combustion synthesis
• hot pressing
• nanoindentation