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Assessment tribological properties of coatings applied by HVOF technology

Brezinová J., Guzanová A., Draganovská D., Egri M.

Acta Mechanica et Automatica

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2013

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Vol. 7, no. 3

135--139

EN

In this article, the attention is paid to the HVOF (High Velocity Oxygen Fuel) thermal spraying method by which the progressive coatings are applied on basic material C15E (STN 412020). These coatings are based on C-17CO, WC-CO-Cr and Cr3C2-25NiCr. There was made determination of the chemical composition of the coatings and assessment of coatings quality - adhesion, microhardness, porosity and wear resistance at room temperature (21°C) and also at operational elevated temperature (900°C). Results of adhesive wear showed high quality of all evaluated coatings and their suitability to extreme tribological conditions.

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High-temperature corrosion resistance of NiAl(Cr)-Al2O3 coating in N2+9%O2+0.2% HCl+0.08%SO2 atmosphere

Formanek B., Szczucka-Lasota B.

Journal of Achievements in Materials and Manufacturing Engineering

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2010

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Vol. 43, nr 2

586--596

EN

Purpose: The aim of this study was to determine the resistance of nickel and aluminium intermetallic phase-based coatings, modified with chromium and aluminum oxides, and to determine the hypothetical mechanism of these materials’ corrosion. Design/methodology/approach: The selected results of high temperature corrosion resistance of HVOF sprayed coatings with NiAl intermetallic phases are presented. The aggressive corrosion gas included: N2+9%O2+0.2% HCl+0.08%SO2. The temperature of cyclic corrosion test was 927 K and the exposure time was 500 h. The macro and microstructure of coatings after and before corrosion test were analyzed by optics and scanning microscopy. The thermodynamically diagrams and phase diagrams of corrosion products after the test are presented. The phase composition of corrosion products was determined by X-ray analysys. Findings: The proposed mechanism and growth of corrosion products on the NiAl(Cr)-Al2O3coatings are shown. The carried out tests allow the characterisation of the properties of coatings with NiAl phase, and supplement the state of knowledge in the scope of their high temperature corrosion resistance. Practical implications: The new elaborated coating can be applied in elevated temperature and aggressive environments for protection of water walls boilers or waste combustors. Originality/value: The elaboration of proposed mechanism of growth corrosion products on the NiAl(Cr)-Al2O3coating and the presentation of reaction during the corrosion process and degradation of coating.

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Mechanizm odporności korozyjnej powłok NiAl(Cr) w środowisku utleniającym

Formanek B., Szczucka-Lasota B., Hernas A.

Ochrona przed Korozją

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2008

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nr 4-5

140-143

PL

Artykuł przedstawia wybrane wyniki badań odporności korozyjnej powłok NiAl(Cr) w środowisku utleniającym. Powłoki wytwarzano w procesie naddźwiękowego natryskiwania cieplnego, HVOF. Prezentowane rezultaty wraz z analiza literaturową zagadnienia stanowiły podstawę opracowania zaprezentowanego mechanizmu korozji wysokotemperaturowej omawianych materiałów. W artykule podkreślono wpływ tlenku glinu i chromu na odporność korozyjną powłok z fazami międzymetalicznymi NiAl. Prezentowane powłoki z fazami międzymetalicznymi i dyspersyjnymi tlenkami charakteryzują się wysoką odpornością korozyjną.

EN

Selected results of investigations of corrosion resistance of NiAl(Cr) coatings in oxidative environment are presented in the article. Coatings were obtained by HVOF thermal spraying method. Experimental results and study of literature data are the basis for the elaboration of the high temperature corrosion mechanism of those materials. The influence of alumina and chromium oxide on the corrosion resistance of the coatings with intermetalic NiAl phase are also shown. The intermetalic coatings strengthened by dispersion oxides have high oxidation resistance.

4

Korozja wysokotemperaturowa natryskiwanych HVOF powłok z fazami FeAl-FexAly w atmosferze: N2 + 9% O2 + 0,2% HCl + 0,08% SO2

Formanek B., Szczucka-Lasota B.

Ochrona przed Korozją

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2007

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nr 4

163-169

PL

W artykule przedstawiono wybrane wyniki badań korozji wysokotemperaturowej powłok, typu FexAly-Al2O3, natryskiwanych metodą naddźwiękową. Cykliczny test korozyjny, przeprowadzono w warunkach laboratoryjnych w temperaturze 600oC, czasie 500 godzin, w agresywnej atmosferze zawierającej związki chloru i siarki. Podczas testu obserwowano zmiany korozyjne zachodzące na powierzchni badanych materiałów, rejestrowano krzywe zmian masy próbek oraz wyznaczono stałe przyrostu masy. Przy pomocy mikroanalizy rentgenowskiej oraz rentgenowskiej analizy fazowej określono skład chemiczny i fazowy powstałych produktów korozji. Analizując drogę dyfuzji siarki dla układów trójskładnikowych, diagramy termodynamicznej stabilności faz i porównując uzyskane wyniki z danymi literaturowymi zaproponowano mechanizm korozji wysokotemperaturowej powłok z fazami międzymetalicznymi FexAly. Przeprowadzone badania potwierdziły wysoką odporność kompozytowych powłok z fazami międzymetalicznymi i ich przydatność dla zastosowań do pracy w temperaturze podwyższonej i wysokiej w korozyjnych atmosferach.

EN

Selected results of high temperature corrosion resistance investigations of HVOF sprayed coatings type FeAl-FexAly have been presented. The cyclic laboratory corrosion test was carried out in a sulfur and chlorine contaminated atmosphere at a temperature of 600oC in 500 hours. Corrosion changes on the surface of the investigated materials were observed, weight change curves of the samples were registered and the weight growth constants were determined. The phase and chemical composition of the corrosion products on the surface of the coatings was determined by X-ray phase analysis and X-ray microanalysis. Following an analysis of the sulfur diffusion length for three component systems and of the thermodynamic phase stability diagrams as well as having compared the obtained results with the literature, a high temperature intermetallic FexAly coating corrosion mechanism was proposed. The conducted research has proven the high resistance of composite coatings with intermetallic phases and their applicability for use under increased or high temperatures in corrosive atmospheres.

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The corrosion resistance of HVOF sprayed coatings with intermetallic phases in aggressive environments

Formanek B., Cizner J., Szczucka-Lasota B., Przeliorz R.

Journal of Achievements in Materials and Manufacturing Engineering

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2006

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Vol. 16, nr 1-2

46--50

EN

Purpose: The cyclic corrosion behavior of coatings with intermetallic matrix ( FeAl, NiAl and FeAl-TiAl) was investigated in aggressive gases. Design/methodology/approach: The composite coatings strengthened by a fine dispersive Al2O3 and other ceramic phases were thermally sprayed by HVOF method in Jet Kote 2 system. A kinetics test was carried out by periodic method for exposure times of up to 500 hours. Mass changes of the studied coatings during the corrosion test are presented. The surfaces of the composite coatings after the corrosion test in aggressive environments were analyzed by scanning microscopy observation. Findings: All the results confirm good heat proofness of HVOF sprayed coatings with an AlFe and AlNi intermetallics. Practical implications: Owing to the properties of intermetallic phases and HVOF sprayed coatings, they are anticipated to be applied for the protection of super heater tubes in conventional boilers or in boilers burning multicomponent waste, and combusted biomass including chlorides. Originality/value: The results show that the coatings with AlFe and AlNi intermetallic phases have very good corrosion resistance and they are the best coatings from all the coatings investigated in aggressive environments.