Plasma-sprayed coatings

The Tribaloy aUoy T-800, is from an aUoy family developed by DuPont in the eady 1970s, in the search for resistance to abrasion and corrosion. Excessive amounts of molybdenum and sUicon were aUoyed to induce the formation during solidifica tion of hard and corrosion-resistant intermetaUic compounds, known as Laves phase. The Laves precipitates confer outstanding resistance to abrasion, but limit ductUity. As a result of this limited ductUity the aUoy is not generaUy used in the form of plasma-sprayed coatings. 

In summary, preliminary studies indicate that plasma spray coatings show great potential for improving the bondability of steel. Potential drawbacks include the requirement for relatively expensive plasma spray equipment and the necessity to keep the substfate temperature below that which would lead to undesirable metallurgical changes. 

The electronic conductivity depends significantly on the preparation and crystalline structure of the LSM specimen. Li et al. [7] prepared LSM samples by conventional sintering and plasma spraying. Depending on the composition, the electronic conductivity of the sintered sample is between 40 and 485 Scm 1 at 1,000°C and that of plasma-sprayed coatings between 50 and 201 Scm . The electronic conductivity of the plasma-sprayed samples is 50% lower than that of the sintered sample. On an... 

Early bubbling FBC units were designed to burn coal, and the heat released was removed by heat transfer to in-bed tubes and/or to the water-wall tubes used to enclose the furnace. These surfaces experienced high rates of metal loss through the combined effects of erosion and abrasion. Protective measures such as plasma-sprayed coatings and metal fins to disrupt the solids flow pattern were used. These were effective for only short periods before requiring replacement, and so maintenance requirements were high. 

W.J. Dhert, C.P. Klein, J.G. Wolke, E.A. van der Velde, K. de Groot, P.M. Rozing, A mechanical investigation of fluorapatite, magnesium whitlockite, and hydroxylapa-tite plasma-sprayed coatings in goats, J. Biomed. Mater. Res. 25 (1991) 1183-1200. 

In the field of metallic powder applications, a method of plasma spray coating suitable for biomedical materials has been developed using titanium and calcium phosphate composite powder. By means of the mechanical shock process, the appropriate composite powder was prepared, and plasma sprayed on Ti substrate under a low-pressure argon atmosphere. A porous Ti coating layer was obtained in which the surface and the inside of the pores were covered thinly with hydroxyapatite. This surface coating is expected to show excellent bone ingrowth and fixation with bone (21). 

Plasma spray coatings have been evalnated as snrface treatments for aluminnm, titanium and steel snbstrates prior to adhesive bonding. These treatments are environ-... 

Obviously the tertiary structure of the catalyst obtained by cold rolling is optimal and is least efficient for the plasma-sprayed coating. It should be stressed that by variation of the process parameters, also galvanically generated NiZn codeposits yield optimal performance, which is comparable to that of cold-rolled coatings (83). 

The physical and metallurgical properties of plasma sprayed coatings are generally superior to all other flame spraying methods, with the exceptions of hypersonic combustion and detonation gun systems. 

Hetman, H. Plasma-Sprayed Coatings Sci. Amer., 112 (September 1988). Lambourne, R. Paint and Surface Coatings Theory and Practice, Prentice-Hall, Inc., Upper Saddle River, NJ, 1993. 

Windes, W.E. and Lessing, P.A., Plasma spray coatings for SOEC, in 2002 Fuel Cell Seminar Abstracts, Courtesy Associates, Washington, DC, 471-474, 2002. 

Hydroxyapatite Plasma Sprayed Coatings on Ti Substrate for Biomedical Applications... 

G. (2001) Plasma-sprayed coatings in the system Ca0-Ti02-Zr02-P205 for longterm stable endoprostheses. Materialwiss. Werkstofftech., 32, 166-171. 

Thickness of APS (atmospheric plasma spraying) coating can be selected between 50 and 250 pm, depending on application however, novel deposition techniques such as suspension or solution plasma-spraying allow coatings with thickness <10 pm. 

Chen, D.Y., Jordan, E.H., and Gell, M. (2010) The solution precursor plasma spray coatings influence of solvent type. Plasma Chem. Plasma Process., 30 (1), 111-119. 

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