Abstract
Borides and carbides attract the attention of developers of heat-resistant and super hard structural materials due to a unique combination of their resistance to high-temperature oxidation, high hardness, wear resistance, electrical and thermal conductivity and etc. The article presents experimental results on obtaining composites based on TiB2-TiC-Al2O3, CrB2-Al2O3 by a method combining self-propagating high-temperature synthesis (SHS) and mechanical activation (MA). The influence of the composition of the initial components, the conditions of SHS and preliminary MA on the formation of the microstructure and phase composition of the SHS-composite based on titanium carbide and titanium, chromium borides has been studied. The SHS products were examined by X-ray diffraction analysis and a scanning electron microscope. High-temperature phases of borides of chromium, titanium, aluminum oxide and their spinel are found in SHS products.
Highlights
Transition metal borides with unique properties are of interest for the preparation of ceramic composites intended for use in high-temperature abrasive wear [1]
Synthesis of borides from simple substances by sintering, hot compaction realized at temperatures lower than the melting points of the initial materials is based on solid phase interaction [1]
The change in the external pressure makes it possible to control the depth of the synthesis, preventing or reducing the loss of the volatile elements of the system, contributing to the retention
Summary
Transition metal borides with unique properties (high refractoriness, wear resistance, thermal conductivity) are of interest for the preparation of ceramic composites intended for use in high-temperature abrasive wear [1]. Strong covalent bonds inherent in the phases of transition-metal diborides lead to low plasticity and low bending and strength, which largely limits their application in pure form. In this regard, currently much attentions paid to the tech-. The use of a heterogeneous mixture with a high combustion temperature, at which the liquid phase forms, allows the first two conditions to be met Under these conditions, SHS products with a large-dispersed microstructure are formed. The use of the preliminary MA to SHS in a planetary mill significantly reduces the temperature of the onset of exothermic interaction of the mixture components, shortens the synthesis time of the combustion product, leads to a more complete course of chemical reactions in the combustion wave. The use of MA at the stage pretreatment of slightly exothermic and difficult to ignite mixtures for synthesis in the combustion mode, in particular for technologies of power SHS-compacting, significantly expands the class obtained ceramics and composites [8,9,10,11,12]
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