Microstructure, mechanical properties and machining performance of hot-pressed Al2O3 - ZrO2 - TiC composites

M Grigoriev,N Kotelnikov,S Buyakova,S Kulkov

doi:10.1088/1757-899x/116/1/012002

Abstract

The effect of adding nanocrystalline ZrO2 and submicron TiC to ultrafine Al2O3 on mechanical properties and the microstructure of the composites developed by hot pressing was investigated. It was shown that by means of hot pressing in an argon atmosphere at a sintering temperature of 1500 °C one can obtain the composites Al2O3 - ZrO2 - TiC with a fine structure and minimal porosity. It has been shown that in material a multi-scale hierarchical structure is formed, which possesses high physical and mechanical properties: the hardness and fracture toughness was 21.5 GPa and 5.2 MPa*m1/2 respectively, the modulus of elasticity was 500 GPa and bending strength was 390 MPa. Tests on composites’ cutting properties were carried out on interrupted cutting of hardened steel. All samples had wear of the cutting edge in the form of chips of the grain rear working surface of the tool, but the cutting tool which was made by Al2O3 - 10% ZrO2 - 10% TiC had a minimum width of wear.

Highlights

The development of ceramic composites with high hardness and chemical inertness, able to withstand prolonged exposure to corrosive environments, high pressure, shock, and temperature, with high resistance to brittle fracture and fracture toughness is the main problem of materials science [1]
Alumina - TiC composites are widely used as cutting tool inserts due to their ability to machine at higher speeds than cemented carbides and their superior hardness, toughness and strength compared to alumina [5]
Alumina - zirconia composites are used as cutting tool inserts where zirconia toughens the alumina matrix by stress induced tetragonal to monoclinic martensitic phase transformation

Summary

Introduction

The development of ceramic composites with high hardness and chemical inertness, able to withstand prolonged exposure to corrosive environments, high pressure, shock, and temperature, with high resistance to brittle fracture and fracture toughness is the main problem of materials science [1] This problem is very important, for example, in the cutting of high-strength tempered steel due to the non-uniform loading of the tool, resulting in the tool life being greatly reduced [2]. Alumina - TiC composites are widely used as cutting tool inserts due to their ability to machine at higher speeds than cemented carbides and their superior hardness, toughness and strength compared to alumina [5] They are commonly known as ‘black ceramics’, having a composition of 70% alumina and 30% TiC, has a high hardness of about 22GPa but insufficient toughness - not more than 4 MPa*m1/2[6].

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Conclusion