I. Pavlenko

MICROSTRUCTURE AND MECHANICAL PROPERTIES OF ALUMINA POWDER COATINGS BY A NEW MULTI-CHAMBER DETONATION SPRAYER

The dense ceramic coatings based on alumina with hardness of 1100±25 HV0.3 and porosity of less than 1% have been prepared by multi-chamber detonation sprayer (MCDS) with a barrel length of 500mm. The intermetallic compound of type FeAl was revealed in the area of the coating that adjoins the substrate.

Synthesis of Magnesium Oxide Nanopowder by Thermal Plasma Using Magnesium Nitrate Hexahydrate

Magnesium oxide (MgO) nanopowder was synthesized by thermal plasma in a novel thermal DC plasma torch using magnesium nitrate hexahydrate. Magnesium nitrate hexahydrate (Mg(NO3)2·6H2O) was obtained from serpentinite (Mg3Si2O5(OH)4; lizardite) (Halilovskiy array, Orenburg region, Russia). The synthesized samples were characterized by analytical techniques including X-ray diffraction (XRD) and transmission electron microscopy (TEM). XRD and TEM characterization studies confirmed that MgO nanopowder obtained has periclase structure with high purity, and the particle sizes vary within the range of 100 nm to 150 nm. We believe that the present work will promote further experimental studies on the physical properties and the applications of MgO nanopowders in the fields such as high-densed ceramics, additives in bactericide, and refractory products.

Properties and Peculiarities of WCCoCr Coatings Formed by Multi-Chamber Detonation Sprayer

Multi-chamber detonation sprayer (MCDS) was applied for deposition of WC-Co-Cr powder coatings on corrosion-resistant steel. Powder AMPERIT®554.074 WC-Co-Cr was used to deposit of a coatings. The coatings microstructures and phase compositions were characterized using SEM, OM and XRD techniques. Measurement of the microhardness of samples was done with a micro-hardness tester DM – 8B using a Vickers’s indenter with load on of 0.3 N. It was established that MCDS has provided the conditions for formation of a dense layer with porosity of less than 1.5 % and microhardness 750±50 HV0.3.

Structure and Microhardness of Titanium-Based Coatings Formed by Multichamber Detonation Sprayer

A series of titanium-based coatings (50–550 μm thick) on an aluminium substrate was deposited via multichamber detonation sprayer with different barrel lengths (300, 400, and 500, all in mm). The titanium-based coatings obtained in these three experiments were examined by optical microscopy, scanning electron microscopy, and X-ray phase analysis. The hardness tests were carried out by the Vickers method with a test load of 50 g. The multichamber detonation sprayer with a barrel length of 500 mm produced the dense layers of coating with hardness of  HV0.05 and porosity of 0.24%, the best result in the experiments.

Deposition and Characterization of CoCrAlY Coatings by Multi-Chamber Detonation Sprayer

In this study, a multi-chamber detonation sprayer (MCDS) was applied for deposition of Co-Cr-Al-Y powder coatings (200-250 mm thick) on nickel base superalloy JS6U (Russia). Powder Co-25Cr-11Al-1Y (d(0.1): 6.6 μm, d(0.5): 62.7 μm, d(0.9): 123,4 μm) was used to deposit of a coatings. The coatings microstructures and phase compositions were characterized using SEM, OM and XRD techniques. Measurement of the microhardness of samples was done with a micro-hardness tester DM – 8B using a Vickers’s indenter with load on of 0.1 N. It was established that MCDS has provided the conditions for formation of a dense layer with porosity 0.05% and microhardness 600±50 HV0.1.