Microstructure and adhesive-cohesive strenght of nickel, tungsten carbide and chromium oxide thermal spray coatings
Abstract
Four thermal spray coatings were applied by oxy-fuel process onto ASTM A743 CA6NM (13Cr-4Ni) steel, namely: two Ni-rich alloys, a chromium oxide and a combined tungsten carbide/Ni-Cr particles coating. The microstructure and adhesive/cohesive strength of the coatings were studied and related to the surface preparation parameters (preheating temperature and surface roughness). The microstructures were studied by XRay diffraction (XRD), scanning electron (SEM) and light optical (LOM) microscopy and hardness was measured according to ASTM E384 standard. The adhesive/cohesive strength was measured according to ASTM C633 standard. The microstructure of the coatings showed porosity (8% for bond coatings and from 15 to 30% for ceramic coatings) within acceptable values for flame spraying Homogeneous coating thicknesses of circa 0.5 mm were obtained. Adhesive strength was among 10 to 19 MPa for most of coatings. The coating-substrate adhesive strength was satisfactory in most cases and significant variations (higher than 25%) in adhesive/cohesive strength were induced by changes in surface preparation parameters, especially in the case of WC/Co-Ni coating.References
D. Crawner, “Thermal Spray Processes, Handbook of Thermal Spray Technology, J,” Int. ASM, 2004.
I. M. Hutchings, “Tribology: friction and wear of engineering materials,” 1992.
K.-H. Zum Gahr, Microstructure and wear of materials, vol. 10. Elsevier, 1987.
J. R. Davis, Handbook of Thermal Spray Technology. ASM International, 2004.
C. Salinas, J. J. Coronado, and G. Latorre, “Evaluación de la multicapa Ni, Al, Mo/Al2O3TiO2, aplicada por el proceso de rociado térmico por combustión,” Rev. Tecnura, vol. 8, no. 16, pp. 15–25, 2005.
R. S. C. Paredes, S. C. Amico, and a. S. C. M. D’Oliveira, “The effect of roughness and pre-heating of the substrate on the morphology of aluminium coatings deposited by thermal spraying,” Surf. Coatings Technol., vol. 200, no. 9, pp. 3049–3055, 2006.
M. Mellali, P. Fauchais, and A. Grimaud, “Influence of substrate roughness and temperature on the adhesion/cohesion of alumina coatings,” Surf. Coatings Technol., vol. 81, no. 2–3, pp. 275–286, 1996.
P. Fauchais, A. Vardelle, M. Vardelle, and M. Fukumoto, “Knowledge concerning splat formation: an invited review,” J. Therm. Spray Technol., vol. 13, no. 3, pp. 337–360, 2004.
A. Nistal, E. García, C. García-Diego, M. I. Osendi, and P. Miranzo, “Flame spraying of adherent silicon coatings on SiC substrates,” Surf. Coatings Technol., vol. 270, pp. 8–15, 2015.
L. Jin, G. Liu, P. Li, H. Zhou, C. Wang, and G. Zhou, “Adhesion strength and thermal shock properties of nanostructured 5La3TiYSZ, 8LaYSZ and 8CeYSZ coatings prepared by atmospheric plasma spraying,” Ceram. Int., vol. 41, no. 9, pp. 12099–12106, 2015.
ASTM, “ASTM NORMA C633. Standard guide to testing adhesion/cohesion of thermal spray coatings.” p. 13, 2001.
A. Toro, “Informe de Proyecto de investigación EPM-UN-COLCIE,” Medellin, 2005.
J. D. Osorio, H. P. Gómez, and A. Toro, “Efecto del tratamiento térmico post soldadura sobre la microestructura del acero inoxidable grado ca6nm para la construcción de rodetes hidráulicos,” Sci. Tech., vol. 1, no. 36, 2007.
J. D. Crawford, “CA6NM an update,” in 29th Annual Steel Founder’s Society of America Techical and Operating Conference, 1974, pp. 1–13.
J. F. Santa, J. C. Baena, and A. Toro, “Slurry erosion of thermal spray coatings and stainless steels for hydraulic machinery,” Wear, vol. 263, no. 1, pp. 258–264, 2007.
R. C. Tucker Jr, “On the relationship between the microstructure and the wear characteristics of selected thermal spray coatings,” Therm. Spraying--Current Status Futur. Trends., vol. 1, pp. 477–482, 1995.
P. Araujo, D. Chicot, M. Staia, and J. Lesage, “Residual stresses and adhesion of thermal spray coatings,” Surf. Eng., vol. 21, no. 1, pp. 35–40, 2005.
J. H. Lindsay, “Coatings and coating processes for metals,” ASM Int. Member/Customer Serv. Center, Mater. Park. OH 44073-0002, USA, 1998. 353, 1998.
D. C. Montgomery, D. C. Montgomery, and D. C. Montgomery, Design and analysis of experiments, vol. 7. Wiley New York, 1984.
J. F. Santa, “Adherencia y resistencia al desgaste erosivo de recubrimientos por aspersión térmica,” Universidad Nacional de Colombia, 2008.
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