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Manufacture of MoO3 Coating Layer Using Thermal Spray Process and Analysis of Microstructure and Properties

Hwang Yu-Jin, Kim Kyu-Sik, Park Jae-Sung, Lee Kee-Ahn

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 4

1535--1538

EN

MoO3 thick film was manufactured by using a thermal spray process (Atmospheric Plasma Spray, or APS) and its micro-structure, phase composition and properties of the coating layer were investigated. Initial powder feedstock was composed of an orthorhombic α-MoO3 phase, and the average powder particle size was 6.7 μm. As a result of the APS coating process, a MoO3 coating layer with a thickness of about 90 μm was obtained. Phase transformation occurred during the process, and the coating layer consisted of not only α-MoO3 but also β-MoO3, MoO2. Phase transformation could be due to the rapid cooling that occurred during the process. The properties of the coating layer were evaluated using a nano indentation test. Hardness and reduced modulus were obtained as 0.47 GPa and 1.4 GPa, respectively. Based on the above results, the possibility of manufacturing a MoO3 thick coating layer using thermal spray is presented.

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Comparative Rolling Contact Behavior of Two APS Coatings with Different Matrix

Chicet Daniela, Toma Stefan, Haraga Radu, Bejinariu Costica

Archives of Metallurgy and Materials

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2022

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Vol. 67, iss. 3

869--878

EN

In this study we analyzed the rolling contact fatigue behavior of two types of coatings made by thermal coating, by the method of atmospheric plasma spraying (APS) from two commercially available powders: Ni5Al5Mo and Al2O3 - 13 TiO2. The contact fatigue behavior was studied on an installation specially designed. The specimens were tested for 54 hours (at 1380 rpm), at a load of 944 N. For both types of coatings, the appearance of a wear path was observed, much more obvious in the case of the Ni matrix layer, also confirmed by profilometry. The mechanism of the wear phenomenon was predominantly of plastic deformation type (the material was pushed towards the edges of the wear path) in the case of NiAlMo coating. In the case of ceramic coating, the wear path width was very small (300-450 μm), with very few changes at the surface level of the coating, which recommends this type of material for applications that require wear resistance to rolling.

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Research into morphology and properties of TiO2 – NiAl atmospheric plasma sprayed coating

Maruszczyk A., Dudek A., Szala M.

Advances in Science and Technology. Research Journal

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2017

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Vol. 11, no 3

204--210

EN

Titania (TiO2) based coatings are ceramic products with unique properties that make them widely applicable (e.g. in automotive industry, optoelectronics, chemical processing or medicine). Atmospheric plasma spray process enables to deposit TiO2 with addition of NiAl feedstock material which has an influence on coating cohesion and adhesion to substrate. However, the literature and technical notes give little information about parameters of spraying of TiO2-10 wt.% NiAl feedstock powders enables producing coating without nonuniformities including cracks and delamination form substrate. The aim of the work was to verify the parameters of plasma spraying by evaluation of the morphology and properties of manufactured the TiO2-10 wt.% NiAl coatings. Titania based coatings were deposited by means of atmospheric plasma sprayed on steel substrate using TiO2-10 wt.% NiAl feedstock powders. Morphology and microstructure were examined using light optical microscope (LOM) and scanning electron microscope (SEM). Coating chemical composition were analysed by means of SEM-EDS method. Coating surface topography and Knoop microhardness were determined. Porosity and thickness were evaluated by using quantities image analysis programme. Plasma spraying parameters used in our research allow to obtain uniform coating without cracks and delamination at coating-substrate interface. It acknowledges that uniformity of coating technological properties as well manufactured coatings can be put to wear tests, such as high temperature oxidation, corrosion, erosion or cavitation erosion resistance evaluation.