TRY-OUT OF SPRAYING MODES AND PROPERTIES OF WEAR RESISTANT Al2O3–TiO2 FLAME COATINGS OBTAINED USING FLEXIBLE CORD MATERIAL

Al₂O₃–TiO₂-based coating specimens were obtained using the method of oxyfuel gas spraying of a flexible cord. The paper studies the influence of process parameters and  composition of the sprayed material on  the structure, composition and  mechanical properties of coatings. It was shown that the increase in spraying distance and  feed rate of the sprayed material leads to reduction in their density. An increased concentration of the  low-melting TiO₂ component preconditions a decrease in coating porosity and has no significant effect on its hardness. During measuring scratching, the Al₂O₃–TiO₂ flame coatings formed with minimal porosity (porosity ~ 3,2 %) are characterized by cohesive fracture behavior and no substrate break up at the 90 N load applied to the indenter. The studied coatings show changes in their friction factor from  0,2  to 0,78  after 2800 counterbody revolutions (44  m of rubbing path). This is due to accumulated fatigue cracks in the coating material and  its subsequent cohesive fracture through formation of large fragments that serve as an abrasive.

1. Baldaev L.H., Borisov V.N., Vahalin V.A., Gannochenko G.I., Zatoka A.E., IvanovA.V., Kudinov V.V., Yaroslavcev V.M. Gazotermicheskoe napylenye: Uchebnoe posobie [Thermal spraying: themanual]. Moscow: MarketDS, 2007.

2. Utenkov V.M., Zaycev A.N. Issledovanie tribotehnicheskih haracteristik perspektivnyh iznosostoikih plazmennyh pokrytyi pri trenii skolzhenia bez smazki [The study of tribotechnical characteristics of advanced wear-resistant plasma coatings on friction sliding without lubrication]. Novye materialy i tehnologii. 2013. No. 11. P. 81—89.

3. Dorfman M. Thermal spray materials. Adv. Mater. Proces. 2002. Vol. 160. P. 49—51.

4. Kudinov V.V. Plazmennye pokrytya [Plasma coating]. Moscow: Nauka, 1977.

5. Kasparova M., Houdkova S., Cubrova J. Thermally sprayed coatings for high temperature application // Proc. 21-st Int. Conf. on Metallurgy and Material (Brno, Czech Republic, 23—25. 05. 2012). P. 144—146.

6. Vargas F., Ageorges H., Fournier P. Mechanical and tribological performance of Al2O3—TiO2 coatings elaborated by f lame and plasma spraying. Surf. Coat. Technol. 2010. Vol. 205. P. 1132—1136.

7. Habib K.A., Saura J.J., Ferrer C. Comparison of f lame sprayed Al2O3/TiO2 coatings: Their microstructure mechanical properties and tribology behavior. Surf. Coat. Technol. 2006. Vol. 201. P. 1436—1443.

8. Hazar H., Ozturk U. The effects of Al2O3—TiO2 coating in a diesel engine on performance and emission of corn oil methyl ester. Renewable Energy. 2010. Vol. 35. P. 2211—2216.

9. Yilmaz S. An evaluation of plasma-sprayed coatings based on Al2O3 and Al2O3—13%TiO2 with bond coat on pure titanium substrate. Ceram. Inter. 2009. Vol. 35. P. 2017—2022.

10. Mishra N.K., Mishra S.B., Kumar R. Oxidation resistance of low-velocity oxy fuel-sprayed Al2O3—TiO2 сoating on nickel-based superalloys at 800 °C. Surf. Coat. Technol. 2014. Vol. 260. P. 23—27.

11. Kenya Hamano, Chii-Shyang Hwang, Zenbe-e Nakagawa, Yutaka Ohya. Effect of TiO2 on sintering of alumina ceramic. J. Ceram. Soc. Jap. 1986. Vol. 94. Р. 505—511.

12. Kang J.J., Xu B.S., Wang H.D. Inf luence of spraying parameters on the microstructure and properties of plasma-sprayed Al2O3/40%TiO2 coating. Phys. Proc. 2013. Vol. 50. P. 169—176.

13. Wank A., Reisel G., Wielage B. Diffusion barrier coatings for graphite, C/C and C/SiC racks in vacuum heat treatment or high temperature brazing processes. ITSC. 2005. Vol. 4. P. 135—138.

14. Barrios de Arenas I. Reactive sintering of aluminum titanate, sintering of ceramics — new emerging techniques. Ed. A. Lakshmanan. InTech. 2012. P. 501—526.

15. Standard ASTM E2109. Standard test methods for determining area percentage porosity in thermal sprayed coatings.

16. Oliver W.C., Pharr G.M. An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments. J. Mater. Res. 1992. Vol. 7. No. 6. P. 1564—1583.

17. Blinkov I.V., Volkhonskiy A.O., Belov D.S., Blinkov V.I., Schatalov R.L., Andreev V.A. Svoistva nanostructurnih keramico-metallicheskih pokrytyi TiN—Ni, poluchennyh ionno-plazmennyh vacuumno-dugovym metodom [Properties of nanostructured ceramic and metallic coatings of a TiN—Ni obtained by ion-plasma vacuum-arc method]. Izv. vuzov. Tsvet. metallurgia. 2014. No. 4. P. 51—58.