The effects of boriding on metal-ceramic bond strength of Co–Cr alloy fabricated by selective laser melting

Abstract

Boriding is a method used to increase the biocompatibility and strength of metallic materials. However, by this time, no study has been encountered in the literature regarding investigation of the effects of boriding on metal-ceramic bond strength of Co–Cr alloy fabricated by selective laser melting. Boriding of metallic surfaces may be an alternative to increase the roughness and adhesion strength of the metal surface. The aim of this study was to analyze the effects of boriding on the metal-ceramic bond strength of a Co–Cr alloy fabricated by selective laser melting. In this study, metal substructures of 0.1 mm, 0.2 mm and 0.3 mm thickness values were produced from CoCrW powders with the method of selective laser melting, borided at 900 °C for 1 h and coated with porcelain. After the procedures, the effects of the boriding process on metal-porcelain bonding were determined by in vitro fracture tests. The 0.1 mm 900 °C 1 h (521.22 ± 56.37 N), (p < 0.001), 0.2 mm 900 °C 1 h (619.55 ± 20.94 N), (p = 0.051) and 0.3 mm 900 °C 1 h (592.11 ± 260.58 N) specimens showed the highest bond strength, significantly higher than that of the 0.1 mm Untreated (299.88 ± 61.56 N), 0.2 mm Untreated (480.55 ± 11.87 N) and 0.3 mm Untreated (520.00 ± 165.52 N), (p = 0.29) specimens. According to the results, with the help of the boriding process applied on the surfaces of the metal substructure samples, the bonding resistance of the porcelain applied onto the metal substructures increased by approximately 74, 29 and 14% in comparison to the samples that were not borided respectively for the thicknesses of 0.1, 0.2 and 0.3 mm. Boriding of metallic surfaces increased the bond strength of the metal material with ceramics.