On the Plasma-Chemical Synthesis of Nanopowders

This paper presents an overview of nanopowders preparation using low-temperature plasma (LTP). LTP with its unique processing capabilities provides an attractive and chemically unspecific route for powder synthesis. Nanopowders such as oxides, nitrides, carbides, catalysts and other nanopowders have been successfully synthesized in LTP reactors based on high intensity arcs, plasma jets and radio-frequency (r. f.) inductively coupled discharges.

Physical-Chemical Characterization of Nanodispersed Powders Produced by a Plasma-Chemical Technique

This article presents a review on the physical-chemical properties and characteristics of plasma-chemically produced nanodispersed powders （NDP）, such as metals, oxides, nitrides, carbides, and catalysts. The plasma-chemical preparatior~ of the powders was carried out in thermal plasma （TP） created by means of high-current electric arcs, plasma jets, high-frequency （HF） discharges, etc. We also discuss certain properties and characteristics of the NDPs, which are determined largely by the conditions of preparation.

Plasma-chemical Synthesis and Regeneration of Catalysts for CH_4 Steam Conversion

We carried out experimental studies concerning the plasma-chemicalsynthesis(PCS) of a catalyst for CH_4 steam conversion and designed and built the equipment for PCSand/ or regeneration of spent catalyst for CH_4 steam conversion. Under the conditions of anelectric-arc low-temperature plasma (LTP), we studied the Ni-O-Al system and performed acomprehensive physicochemical analysis of the ultradispersed product obtained. It's the first timeworldwide when the conditions of plasma-chemical synthesis and/ or regeneration of CH_4 steamconversion catalysts under the conditions of electric-arc LTP are investigated depending on theplasma-chemical process (PCP) parameters and the plasma-chemical reactor (PCP) type (with CW-'coldwalls' T_W = 500 K or WW-'warm walls' T_W = 1500 K), samples with a specific surface of 120 m^2/gare obtained. Plasma-chemically synthesized and/ or regenerated samples have a homogenous chemicalcomposition similar to that the Girdller (USA) conventional industrial catalyst. It is empiricallyestablished that the optimal temperature range in PCR for synthesis of samples with maximumdispersity is (2000～3000) K. Results from investigation on dynamics and kinetics ofplasma-chemically synthesized and / or regenerated catalysts for CH4 steam conversion show thatunder LTP conditions premises for the formation of catalyst compositions are established. They arereduced 3 to 4 times faster than their industrial analogues. High specific surface of the samples,homogenous composition, high rate of active chemical surface formed by reduction, faulty crystallattice of catalytically active phases and mostly high catalytic activity make them a potentialcompetitor with their industrial analogues for their probable production in catalyst shops.

High-Temperature Thermodynamic Investigation of Nano-Dispersed Nitrides Obtained in Thermal Plasma

The nitrides of transient metals have a high hardness, thermal stability, remarkable wear resistance in aggressive chemical mediums, melted metals and alloys, high corrosion resistance, and low coefficient of electric resistance. Under the conditions of low-temperature argon plasma （LTP）, thermodynamic investigations were conducted in the process of obtaining of A1N, TiN and Si3N4 in a temperature range of 1000 K to 6000 K. To investigate the thermodynamic possibility of obtaining nitrides, a computer model was used which provided the equilibrium composition of gaseous and solid phases at different temperatures. The conditions for chemical equilibrium of the system were based on the minimization of Gibbs＇ energy.

The Design and Manufacturing of Diffraction Optical Elements to form a Dot-Composed Etalon Image within the Optical Systems

The possibilities of manufacturing of diffraction optical elements (DOE), using the “Caroline 15 PE” plasma-etching machine were considered. It is established that at thickness of chromic mask of 100 nm the plasma-chemical etching (PCE) method reaches depth of surface micro-profile to 1.4 μm on optical glass. It allows increasing the diffraction efficiency of DOE to 0.3 - 0.35 on the second order of diffraction.