A study of the influence of TiO2 addition in Al2O3 coatings sprayed by suspension plasma spray

In this work, five different concentrations of a mixture of TiO2/Al2O3 nanopowders in an alcoholic suspension at 10wt.% solid content were sprayed by Suspension Plasma Spraying on steel discs. The influence of the presence of TiO2 at 0, 13, 40 and 75wt.% in Al2O3 was analysed by studying the properties of the sprayed coatings. Microscopy analysis of the projected coatings revealed a homogeneously distributed microstructure, where the densification of the coating increases with TiO2 content, while the original nanostructure is maintained. A nanoindentation study revealed an increment of nanohardness and elastic modulus due to the densifying effect of TiO2. The addition of significant amounts of TiO2 has been revealed as necessary in order to favour the fusion of Al2O3 in the SPS process

Microstructure and photocatalytic activity of suspension plasma sprayed TiO2 coatings on steel and glass substrates

In this study, TiO 2 coatings were deposited by suspension plasma spraying (SPS) from a commercial TiO 2 nanoparticle suspension on two different substrates: a standard stainless steel and a Pyrex glass. Coatings were sprayed on both substrates with an F4-MB monocathode torch; a Triplex Pro tricathode torch was also used to spray coatings just on the stainless steel substrates. Spraying distance and cooling were varied.The anatase content in the coatings, determined by XRD, ranged from 32 to 72 wt% A significant amount of anatase to rutile transformation was found to occur during cooling. Examination of the microstructure revealed that the coating microstructure was bimodal, involving a non-molten region consisting mainly of anatase nanoparticle agglomerates and a molten region. The glass substrate coatings displayed a segregated phase distribution, particularly when the surface to be coated was cooled. Photocatalytic activity was determined by a methylene blue test.The experimental data fitted well to a first-order kinetic. All the coatings exhibited high photocatalytic activity in comparison with that of a commercial sol-gel coating. However, unlike much of the previous research, photocatalytic activity did not correlate with the anatase content determined by XRD. © 2011 Elsevier B.V.This work has been supported by the Spanish Ministry of Science and Education (MAT2009-14144-C03-01), by the Spanish Ministry of Science and Innovation (PID-600200-2009-5) and by the European Commission in the frame of the Interreg IV B Sudoe programme (Eliare: SOE1/P1/F169).Bannier, E.; Darut, G.; Sánchez, E.; Denoirjean, A.; Bordes, M.; Salvador Moya, MD.; Rayón Encinas, E.... (2011). Microstructure and photocatalytic activity of suspension plasma sprayed TiO2 coatings on steel and glass substrates. Surface and Coatings Technology. 206(2):378-386. https://doi.org/10.1016/j.surfcoat.2011.07.039S378386206

Sliding Wear Behavior of Al2O3-TiO2 Coatings Fabricated by the Suspension Plasma Spraying Technique

[EN] The friction and dry sliding wear behavior of alumina and alumina-titania near-nanometric coatings were examined. Coatings were obtained by the suspension plasma spraying technique. Dry sliding wear tests were performed on a ball-on-disk tribometer, with an Al2O3 ball as counterpart material, a normal load of 2 N, a sliding distance of 1200 m and a sliding speed of 0.1 m/s. The effect of including TiO2 in the fabricated coatings on friction coefficient behavior, wear rates and wear damage patterns was determined. The addition of TiO2 to the coatings was found to greatly increase wear resistance by, for example, 2.6-fold for 40 wt% of TiO2. The analysis of the wear surface was correlated with microstructural parameters, mechanical properties and wear rates.The authors wish to thank for the Spanish Ministry of Economy and Competitiveness (MAT2012-38364-C03) and the Autonomous Government of Valencia for funding for the stay in SPCTS-UMR CNRS (France), and the French FCENANOSURF consortium funded by the French Ministry and Industry and local governments of Region Centre and Region Limousin.Klyatskina, E.; Espinosa Fernández, L.; Darut, G.; Segovia López, EF.; Salvador Moya, MD.; Montavon, G.; Agorges, H. (2015). Sliding Wear Behavior of Al2O3-TiO2 Coatings Fabricated by the Suspension Plasma Spraying Technique. Tribology Letters. 59(1):1-9. https://doi.org/10.1007/s11249-015-0530-5S19591Pawlowski, L.: The Science and Engineering of Thermal Spray Coatings. Wiley: Hoboken (2008)Lampe, Th, Eisenberg, S., Cabeo, E.R.: Plasma surface engineering in the automotive industry—trends and future prospective. Surf. Coat. Technol. 174–175, 1–7 (2003)Wang, Y., Jiang, S., Wang, M., Wang, S., Xiao, T.D., Strutt, P.R.: Abrasive wear characteristics of plasma sprayed nanostructured alumina/titania coatings. Wear 237, 176–185 (2000)Kabacoff, L.T.: Nanoceramic coatings exhibit much higher toughness and wear resistance than conventional coatings. AMPITAC Newslett. 6(1), 37–42 (2002)Wang, M., Shaw, L.L.: Effects of the powder manufacturing method on microstructure and wear performance of plasma sprayed alumina–titania coatings. Surf. Coat. Technol. 202, 34–44 (2007)Shaw, L.L., Goberman, D., Ren, R., Gell, M., Jing, S., Wang, Y., Xiao, T.D., Strutt, P.R.: The dependency of microstructure and properties of nanostructured coatings on plasma spray conditions. Surf. Coat. Technol. 130, 1–8 (2000)Dahotre, N.B., Nayak, S.: Nanocoatings for engine application. Surf. Coat. Technol. 194(1), 58–67 (2005)Sathish, S., Geetha, M., Aruna, S.T., Balaji, N., Rajam, K.S., Asokamani, R.: Sliding wear behavior of plasma sprayed nanoceramic coatings for biomedical applications. Wear 271, 934–941 (2011)Pawlowski, L.: Finely grained nanometric and submicrometric coatings by thermal sparing: a review. Surf. Coat. Technol. 202, 4318–4328 (2008)Xiao, D., Wang, Y., Strutt, P.: Fabrication and evaluation of plasma sprayed nanostructured alumina–titania coatings with superior properties. Mater. Sci. Eng. 301, 80–89 (2001)Tjong, S.C., Chen, H.: Nanocrystalline materials and coatings. Mater. Sci. Eng. 45, 1–88 (2004)Fauchais, P., Montavon, G., Bertrand, G.: From powders to thermally sprayed coatings. J. Therm. Spray Technol. 19, 56–80 (2010)Lima, R.S., Marple, B.R.: Thermal spray coatings engineered from nanostructured ceramic agglomerated powders for structural, thermal barrier and biomedical applications: a review. J. Therm. Spray Technol. 16, 40–63 (2007)Fauchais, P., Etchart-Salas, R., Delbos, C., Tognonvi, M., Rat, V., Coudert, J.F., Chartier, T.: Suspension and solution plasma spraying of finely structured layers: potential application to SOFCs. J. Phys. D Appl. Phys. 40, 2394–2406 (2007)Ramachandran, K., Selvajaran, V., Ananthapadmanabhan, P.V., Sreekumar, K.P.: Microstructure, adhesion, micro hardness, abrasive wear resistance and electrical resistivity of the plasma sprayed alumina and alumina–titania coatings. Thin Solid Films 315, 144–152 (1998)Lee, S.W., Morillo, C., Lira-Olivares, J., Kim, S.H., Sekino, T., Niihara, K., Hockey, B.J.: Tribological and microstructural analysis of Al2O3/13TiO2 nanocomposites to use in femoral head of hip replacement. Wear 225, 1040–1044 (2003)Dejang, N., Watcharapasorn, A., Wirojupatump, S., Niranatlumpong, P., Jiansirisomboon, S.: Fabrication and properties of plasma-sprayed Al2O3/TiO2 composite coatings: a role of nano-sized TiO2 addition. Surf. Coat. Technol. 204, 1651–1657 (2010)Yimaz, S.: An evaluation of plasma sprayed coatings based on Al2O3 and Al2O3–13wt% TiO2 with bond coat on pure titanium substrate. Ceram. Int. 35, 2017–2022 (2009)Fervel, V., Normand, B., Coddet, C.: Tribological behavior of plasma sprayed Al2O3-based cermet coatings. Wear 230(1), 70–77 (1999)Vargas, F., Ageorges, H., Fauchais, P., López, M.E.: Mechanical and a tribological performance of Al2O3 coatings elaborated by flame and plasma spraying. Surf. Coat. Technol. 205, 1132–1136 (2010)Bacciochini, A., Ilavsky, J., Montavon, G., Denoirjean, A., Ben-ettouil, F., Valette, S., Fauchais, P., Wittmann-teneze, K.: Quantification of void network architectures of suspension plasma-sprayed (SPS) yttria-stabilized zirconia (YSZ) coatings using ultra-small-angle X-ray scattering (USAXS). Mater. Sci. Eng. 528, 91–102 (2010)ASTM International: ASTM G99-03: Standard test method for wear testing with a pin-on-disc apparatus. ASTM annual book of standards. 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Experimental and numerical investigation of cavitation-induced erosion in thermal sprayed single splats

Hydraulic components are coated by thermal spraying to protect them against cavitation erosion. These coatings are built up by successive deposition of single splats. The behavior of a single splat under mechanical loading is still very vaguely understood. Yttria-stabilized zirconia (YSZ) and stainless-steel splats were obtained by plasma spraying onto stainless steel substrates. The velocity and temperature of particles upon impact were measured and the samples were subsequently exposed to cavitation erosion tests. An acoustic cavitation simulation estimated the water jet velocity and hammer stresses exerted by bubble collapse on the surface of the specimen. Although the results suggested that high stress levels resulted from cavitation loading, it was clear that weak adhesion interfaces played a crucial role in the accelerated cavitation-induced degradation.EPSRC (UK

Tribological performances of YSZ composite coatings manufactured by suspension plasma spraying

International audienceNanostructured coatings are more and more considered in scientific literature because of their benefit contributions in improving coating properties such as toughness, wear resistance or thermal properties. In conventional plasma spraying, agglomeration of nanometer-sized particles into micrometer-sized feedstock can be injected using a carrier gas to obtain a bimodal structure. Or, since now ten years, a liquid carrier (Suspension Plasma Spray process, SPS) is employed to drive nanometer or sub-micrometer sized particles into the plasma jet with a limited agglomeration of the particles. With SPS, the reduced microstructural size of coatings improves their tribological properties, especially for ceramic coatings. This study aims at studying yttria stabilized zirconia (YSZ) coatings manufactured by suspension plasma spraying. The primary objective of this work is to improve tribological performances of YSZ coatings, which is found to be better when a higher plasma enthalpy is used to elaborate them. The second objective is to incorporate reinforcements within the YSZ matrix to improve further performances. In that way SiC has been included in the YSZ matrix resulting in a higher wear resistance

Effect of the structural scale of plasma sprayed alumina coatings on their friction coefficients

International audienceThe objective of this study is to compare the tribological properties of alumina coatings with two different structural scales, a micrometer-sized one manufactured by atmospheric plasma spraying and a sub-micrometer-sized one manufactured by suspension plasma spraying. Coating architectures were analyzed and their friction coefficients in dry sliding mode measured. Sub-micrometer-sized structured coatings present a lower friction coefficient than micrometer ones, thanks to their higher cohesion and smaller characteristic structural feature size

Towards hybridization of ultra-high molecular weight polyethylene composites by thermally sprayed alumina: Feasibility and bond strength assessment

International audienc

Towards hybridization of ultra-high molecular weight polyethylene composites by thermally sprayed alumina: Feasibility and bond strength assessment

International audienc