Abstract
The methods for activating sintering ceramics based on Al2O3 by mechanical activation in the planetary mill, by adding in the mixture of nanopowders (NP) Al, Al2O3, and submicron powder TiO2, and by applying the technology of spark plasma sintering (SPS) are developed. It has been shown that adding the nanopowder up to 20 wt. % Al2O3 in a coarse powder α-Al2O3 activates the sintering process resulting in increased density and hardness of the sintered alumina ceramics. Substantial effect of increasing density of alumina ceramics due to adding the submicron powder TiO2 in the compound of initial powder mixtures has been established.
Highlights
Compacting ceramic powders can be carried out using cold pressing with static one- or two-sided application pressure; hot pressing; cold or hot isostatic pressing in hydro- or gazostats; hot extrusion; slip casting; magnetic pulse, impact molding and explosive compacting; ultrasonic compaction
It is shown that adding the nanopowder Al2O3 to the content of 20 wt. % to the coarse-dispersed powders α-Al2O3 of grades technical and white alumina activated a sintering process of corundum ceramics that led to increase in its relative density and hardness from 70.2 to 72.2% and from 62.3 to
When adding of nano-dispersed Al in the NP Al2O3 decrease in the density and the hardness of sintered ceramics due to the additive oxidation up to α-Al2O3 was observed. This led to reduced specific volume of the final product of the added additive caused by significant difference of Al and α-Al2O3 density, and decrease in density of sintered ceramics
Summary
Compacting ceramic powders can be carried out using cold pressing with static one- or two-sided application pressure; hot pressing; cold or hot isostatic pressing in hydro- or gazostats; hot extrusion; slip casting; magnetic pulse, impact molding and explosive compacting; ultrasonic compaction. The complexity and poor performance technology of hot and hot isostatic pressing [1,2]. Allowing to obtain materials with high strength properties [3] prevent the wide practical use of solid alumina ceramics. A relatively simple technique of uniaxial pressing with following sintering generally cannot produce ceramics with the high level of mechanical properties [4]. The problem of activating processes of consolidation alumina ceramics is of practical importance. The aim of this work is to develop methods to activate the sintering process of the ceramics based on Al2O3 powders by mechanical treatment in a planetary ball mill and adding to the mixture of nanopowders (NP) Al, Al2O3 and submicron powder TiO2 as well as application of spark plasma sintering (SPS) technology
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