My research focuses on the design of the process for optimum deposition of thermal spray coatings. The objective is to deposit coatings of desired properties to enhance their performance on applications. The approach used towards understanding coating formation involves process maps (particle state control by process parameters), real-time monitoring of stress evolution (design of the intersplat interface and crack architecture) and property evaluation. Successful management of process parameters has allowed us to tailor properties, for example: tailoring residual stress increases fatigue resistance of coatings, tailoring particle state can reduce oxidation and increase hardness of alloys and cermet coatings, tailoring particle flux and substrate temperature produces strain tolerant coatings, etc. Case studies have been developed for WC-CoCr, WC-Co, CrC-NiCr, YSZ, MCrAlY’s, NiCr, Stellite, T-800, etc, with various torches: DJ, JK,JP-5000, HV-2000, Triplex, Plasma 4MB, 7MB, F4, etc. Special consideration is given for reproducibility in production and reliability in-service of theses coatings.
My interests are in the plasma and HVOF processing for applications in turbines for aerospace industry, corrosion and wear resistant coatings for Hard Chrome Replacement, sensors via thermal spray and development of new materials and torches.
Publications
- A. Valarezo. Process Design for Reliable High Velocity Thermal Spray Coatings: An Integrated Approach through Process Maps And Advanced Insitu Characterization. SUNY Stony Brook, Materials Science and Engineering Department, Thesis Dissertation.
- A. Valarezo, E. Mari and S. Sampath, Understanding Coating Formation in Real Time via Monitoring of Residual Stress Development, International Thermal Spray Conference, Maastricht ,Netherlands, June 2008
Best Young Scientist Contribution Award
- A.Valarezo, J.Japson, A.Gouldstone and S.Sampath, Residual stress development in metallic coatings by HVOF spraying, Proceedings of International Thermal Spray Conference, China, May 2007
- A.Valarezo, W.B.Choi, W.Chi, A.Gouldstone and S.Sampath, Process maps of NiCr coatings by HVOF spraying, Proceedings of International Thermal Spray Conference, China, May 2007.
- T.Varis, E.Turunen, A.Valarezo, S.Sampath, X.Liu, S.P.Hannula, Formation mechanisms, structure and properties of HVOF sprayed WC-CoCr coatings: An approach towards process maps, Proceedings of International Thermal Spray Conference, Beijing, China, May 2007.
- A. Valarezo, T. Varis, S. Sampath, A Fundamental Approach to the Tribological Response of Cermet Coatings by HVOF Spraying. International Cocoa Beach Conference on Advanced Ceramics and Composites, American Ceramic Society, Daytona Beach, USA. January 2007.
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