Abstract
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 (PECVD), 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 a N2 plasma for 10 min, 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.
Highlights
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
These results indicate that coating glass-ceramics in silicon carbide (SiC) could be an effective way to mitigate corrosion effects, further optimization is required to enhance the chemical durability of SiC films to prevent delamination and bubbling
We have demonstrated that post-deposition processing steps such as annealing and N2 plasma treatment can be utilized to improve the chemical durability of SiC-based protective coatings
Summary
Glass-ceramics are often used in fixed dental prostheses such as crowns, veneers, and bridges to restore missing parts of a patient’s dentition. Over time, these glass-ceramics have been shown to undergo corrosion due to the caustic environment of the oral cavity [1,2,3,4,5,6,7,8]. Previous clinical studies have confirmed this, but demonstrate that the severity of the corrosion process is strongly correlated to the pH levels that the ceramics are exposed to [9,10] These corrosion mechanisms lead to a reduced fracture strength of the glass ceramic and cause a roughened surface topography [11,12,13,14]. External modifications do not alter the composition of the glass-ceramic but Materials 2020, 13, 2375; doi:10.3390/ma13102375 www.mdpi.com/journal/materials
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