(162af) Annealing & N2 Plasma Treatment to Minimize Corrosion of SiC Coated Glass-Ceramics

Within the dental industry, glass-ceramics are often used in fixed dental prostheses such as crowns, veneers, and bridges to restore missing parts of a patient’s dentition. Overtime, these glass-ceramics have been shown to undergo corrosion due to the caustic environment of the oral cavity. Out of many potential materials that could protect a glass-ceramic from corrosion, silicon carbide (SiC) is drawing significant interest due to this material’s high strength, lack of reactivity to the oral environment, and ease of deposition. In addition to SiC’s durability, it has also shown favorable biocompatibility in various applications. Although initial reports have shown the promise of SiC based ceramic coatings, significant work is still needed to optimize the chemical durability of the SiC film and ensure the coating does not delaminate over time.

To improve the chemical durability of SiC based coatings on glass-ceramics, the effects of annealing and N₂ plasma treatment were investigated. Fluorapatite glass-ceramic disks were coated with SiC via plasma enhanced chemical vapor deposition, treated with N₂ plasma followed by an annealing step, characterized, and then immersed in a pH 10 buffer solution for 30 days to study coating delamination. Post-deposition annealing was found to densify the deposited SiC and lessen SiC delamination during the pH 10 immersion. When the SiC was treated with an N₂ plasma for 10 minutes, the bulk properties of the SiC coating were not affected but surface pores were sealed, slightly improving the SiC’s chemical durability. By combining N₂ plasma-treatment with a post-deposition annealing step, film delamination was reduced from 94% to 2.9% after immersion in a pH 10 solution for 30 days. X-ray Photoelectron spectroscopy (XPS) detected a higher concentration of oxygen on the surface of the plasma treated films, indicating a thin SiO₂ layer was formed and could have assisted in pore sealing. In conclusion, post-deposition annealing and N₂ plasma treatment where shown to significantly improve the chemical durability of PECVD deposited SiC films used as a coating for glass-ceramics.