Compactability of Stabilized Zirconium Dioxide Powder

Features of compacting articles from stabilized zirconium dioxide powder synthesized by the sol-gel method, and also their structure and properties are studied. Compaction parameters are determined. It is shown that the relationship between compact density and extrusion pressure may be described by the Bal'shin equation. It is established that parameters of this equation depend linearly on the duration of zirconium dioxide synthesis.     

Effect of Nanosized Powders on the Structure and Properties of Electrospark Alloyed Coatings

The influence of nanosized additives ZrO₂, Al₂O₃, W, WC, WC-Co, NbC, Si₃N₄ on mass transfer of the SHS electrode material of the Ti-Cr-Ni-C system (SHIM-3B alloy trade mark) is considered. The thickness, continuity, and microhardness of the electrospark coatings alloyed onto the nickel alloy, as well as the coating structure, wear resistance, and the nanosized powder distribution in the coating have been studied. The coatings obtained have been subjected to X-ray analysis. An optimum performance regime of the ALIER-METAL setup for high-frequency electrospark alloying has been determined. It has been found that addition of nanosized powders to the electrode material facilitates thickening of the electrospark alloying (ESA) coatings and improvement of their continuity, hardness, and wear resistance.     

Structure and properties of dispersion-strengthened-with-nanosized particles refractory hard material TiC—Ni-alloy

Some particularities of the effect of nanocomponents such as ZrO₂,Al₂O₃, W, WC, WC—Co, NbC, Si₃N₄ on the combustion process, the structure, and mechanical properties of a novel electrode dispersion-strengthened alloy TiC—40% Ni have been studied. The refractory hard alloy based on titanium and a nickel alloy has been produced by the method of self-propagating high-temperature synthesis. It has been shown that introduction of a nanosized powder causes reduction of the combustion velocity depending on the specific surface area of the additive. It has been found that upon introduction of nanodispersed powders into the green mixture the product structure undergoes significant modification. The ZrO₂ and NbC additives produce a positive effect on the main mechanical characteristics of the alloy (its strength, hardness, and crack resistance). In contrast, these properties are negatively affected by the Al₂O₃ and Si₃N₄ nanopowders. Enhancement of the material bending strength and crack resistance can be achieved by respective addition of WC—Co and W, WC. © 2003 Elsevier Ltd. All rights reserved.     

Effects of Nanocrystalline Powders Additions on the Characteristics of Combustion Process, Phase- and Structure-Formation, and Properties of SHS Alloys on Titanium Carbide Base

A study was made of the effect of different nanocrystalline powders additives on the macrokinetics of combusting Ti-Cr-C-Ni mixtures as well as on the composition, structure, and physical-mechanical properties of SHIM-SB alloy produced by the power SHS-compaction technique. An additive of nanocrystalline powder is found to result in 2- to 5-fold modification of alloy structure and, in most cases, in improving physical and mechanical properties (bending strength, hardness, microhardness, and crack growth resistance).     

Effect of Nanocrystalline Powders on the Structure and Properties of Dispersion-Hardened Alloy TiC – 40% KhN70Yu

This article examines aspects of the effect of nanocrystalline powders of ZrO₂, Al₂O₃, W, WC, WC–Co, NbC, and Si₃N₄ on the combustion, structure, and physical and physico-mechanical properties of new dispersion-hardened electrode alloy TiC – 40%KhN70Yu. This heat-resistant hard alloy, based on titanium carbide and a nickel alloy, was obtained by self-propagating high-temperature synthesis (SHS). It is shown that the addition of a nanocrystalline powder decreases combustion rate, with the magnitude of the reduction depending on the specific surface of the addition. It was determined that the structure of the synthesis products is modified appreciably by introducing a mixture of nanocrystalline powders into the initial charge. Here, additions of ZrO₂ and NbC have a positive effect on the main physico-mechanical characteristics of the alloy (strength, hardness, fracture toughness). Nano-powders of Al₂O₃ and Si₃N₄ have a negative effect on the alloy's physico-mechanical properties. The addition of WC–Co increases the flexural strength of the material, while the addition of W and WC increases its fracture toughness.