Cold-Sprayed Ni-Al 2 O 3 Coatings for Applications in Power Generation Industry
- PDF / 1,018,434 Bytes
- 11 Pages / 593.972 x 792 pts Page_size
- 76 Downloads / 228 Views
F. Sevillano, P. Poza, C. J. Mu´nez, S. Vezzu`, S. Rech, and A. Trentin (Submitted September 27, 2012; in revised form December 3, 2012) Cermets coatings are extensively used in energy applications both because of their high wear resistance as required, for example, in components like gas turbine sealants, and because of their specific functionality as required in solar absorbers. So far, high-temperature thermal spraying and physical vapor deposition have traditionally been used to deposit this kind of coatings. In this study, Ni-Al2O3 coatings have been deposited using a KineticÒ3000 cold-spray system starting from Ni and Al2O3 powders blend; five blends have been prepared setting the alumina content in the feedstock to 10, 25, 50, 75, and 90 wt.%. The embedded alumina ranges between a few percent weight up to 16 and 31 wt.%, while the microhardness shows a deep increase from 175 Vickers in the case of pure Ni coatings up to 338 Vickers. The spray and coating growth mechanism have been discussed, with special attention to the fragmentation of the ceramic particles during the impact. Finally, the coating behavior at high temperature was analyzed by oxidation tests performed in air at 520 °C emphasizing a good oxidation resistance that could represent a very promising basis for application in power generation systems.
Keywords
cermet coatings, cold spray, isothermal oxidation, scanning electron microscopy (SEM)
1. Introduction Cermets coatings are formed by ceramic particles embedded in a metallic matrix. They are extensively used in several industrial applications to combine the structural integrity of metals with the higher operating temperature and wear resistance of the ceramics. These coatings exhibit better toughness and thermal sock resistance than the pure ceramic coatings, although the maximum operating temperature and thermal stability is reduced. The powder metallurgy is one of the most considered ways to obtain cermet materials thanks to the great versatility of processable materials and conditions. In this field, thermal-spray techniques are traditionally devoted to produce thin and thick protective cermet coatings and, for example, several industrial case studies in mechanic and mechatronic show that WC-Co and WC-Ni wear-resistant coatings produced mainly by high-velocity oxy-fuel (HVOF) represents today one of the most diffused and successful example of potentiality of cermet materials (Ref 1). Different powder feedstock materials could be employed to deposit cermet coatings; first of all, the use of F. Sevillano, P. Poza, and C.J. Mu´nez, Departamento de Tecnologı´a Meca´nica, Universidad Rey Juan Carlos, Escuela Superior de Ciencias Experimentales y Tecnologı´a, C/ Tulipa´n s.n., 28933 Mo´stoles, Madrid, Spain; and S. Vezzu`, S. Rech, and A. Trentin, Veneto Nanotech scpa, Nanofab Laboratory, via delle industrie, 5, 30157 Marghera, VE, Italy. Contact e-mail: [email protected].
Journal of Thermal Spray Technology
powder blend is reported (Ref 2) and represents the easiest and more ve
Data Loading...
