Sintering and physico-mechanical properties of materials based on silicon nitride nanoscale powders

Obtained a high-density material (ρ = 3,28 g/cm3, a porosity of 1,4 %) on the basis of silicon nitride powder by liquid phase sintering nanoscale. Displaying pressing pressure on the density of sintered materials the based silicon nitride. The process of pattern formation material during sintering. The main physico-mechanical characteristics: the density, porosity and grain size of the solid phase, the modulus of elasticity, flexural strength, fracture toughness ratio, Vickers hardnes

Spark plasma sintering, phase composition, and properties of AlMgB14 ceramic materials

AlMgB14-based materials have been synthesized by spark plasma sintering of an Al12Mg17–B powder mixture at 1300 and 1400°C. The phase composition, structure, and properties of these materials have been studied. According to X-ray powder diffraction evidence, spark plasma sintering leads to the formation of the AlMgB14 phase and the MgAl2O4 spinel. The content of the AlMgB14 phase in the materials is ~95 wt %. At a sintering temperature of 1400°C, the resulting material has a hardness and relative density of 30.1 GPa and 99.3%, respectively. It has been demonstrated that a major source of oxygen in the powder mixture is a B2O3 oxide film on the boron powder surface. Thus, when the Al12Mg17 intermetallic powder is used as a precursor, the reaction of AlxMgy intermetallic compounds with B2O3 leads to the formation of the MgAl2O4 spinel

Structural and mechanical state of AlNiCO35 alloy produced by selective laser melting

The results of studying the structure of additively manufactured permanent magnets based on AlNiCo35 alloy are presented. Structural features are identified with optical and electron microscopy, and the phase composition is determined with X-ray diffractometry. The possibility of manufacturing magnets by selective laser melting of metal powder is show

Effect of Diamond Phase Dispersion on the Properties of Diamond-SiC-Si Composites

The research aimed at the composition optimization for diamond-SiC-Si composites. The effect of a porous diamond workpiece was studied on the properties (porosity, density, modulus of elasticity, phase composition) of the product of its siliconization with molten silicon. The lowest porosity and highest modulus of elasticity were observed in the case of using mixed matrices with the maximum size of diamond grains of 250/200 μm for siliconization. The best results in terms of the sound speed (16,600 m/s) and elasticity modulus (860 GPa) were achieved by microwave processing of a composite containing detonation nanodiamonds

The use of intermetallic AlxMgy powder to obtain AlMgB14-based materials

In this work, AlMgB14-based materials were obtained from powders of the intermetallic compound Al12Mg17 and boron using hot pressing method and mechanical treatment with a planetary mill. The method for producing intermetallic Al12Mg17 powder is presented. The effect of the mechanical treatment on the dispersion of the Al12Mg17 powder was investigated. The phase composition, microstructure, and properties (density, hardness and coefficient of friction) of the AlMgB14-based materials were investigated. The hardness of the obtained sample is 31.9 GPa, and the density is 2.35 g/cm3 (90% of theoretical density). The friction coefficient under dry conditions is 0.38. The friction coefficient under lubricated conditions (LITOL-24 lubricant) is 0.18. The mechanism of AlMgB14 formation was investigated. When using the intermetallic Al12Mg17 powder as a raw precursor of the Al-Mg-B powder mixture, the AlMgB14 phase is formed by direct boration of AlxMg1-xB2 diboride, while the formation of spinel MgAl2O4 phase is due to contamination of the raw boron powder