Air-abrasion using new silica-alumina powders containing different silica concentrations: Effect on the microstructural characteristics and fatigue behavior of a Y-TZP ceramic

• Published in: Journal of the mechanical behavior of biomedical materials 2019-10, Vol.98, p.11-19
• Main Authors: Cadore-Rodrigues, Ana Carolina, Prochnow, Catina, Rippe, Marília Pivetta, Oliveira, Jivago Schumacher de, Jahn, Sérgio Luiz, Foletto, Edson Luiz, Pereira, Gabriel Kalil Rocha, Valandro, Luiz Felipe
• Format: Article
• Language: English
• Subjects: Accelerated fatigue; Flexural fatigue strength; Mechanical cycling; Silica concentration; Surface treatment; Zirconium oxide partially stabilized by yttrium
• ISSN: 1751-6161; 1878-0180
• DOI: 10.1016/j.jmbbm.2019.05.032

This study assessed the fatigue performance (biaxial flexure fatigue strength), surface characteristics (topography and roughness) and structural stability (t-m phase transformation) of a Y-TZP ceramic subjected to air-abrasion using new powders (7% and 20% silica-coated aluminum oxide particles) in comparison to commercially available powders. Disc-shaped specimens were manufactured (ISO 6872–2015) and randomly allocated into four groups considering the air-abrasion materials: SiC: commercially available silica-coated aluminum oxide; AlOx: commercially available aluminum oxide; 7%Si and 20%Si: experimentally produced materials consisting of 7% and 20% silica-coated AlOx, respectively. Air-abrasion was executed by a blinded researcher (1 cm distance from the tip to the specimen surface, under 2.8 bar pressure for 10 s). The fatigue tests (n = 15) were performed by the staircase method under a piston-on-three-balls assembly. Topography and roughness assessments (n = 30) of abraded samples and fractography of failed discs were performed. The highest fatigue strength (MPa) was observed for 7%Si (887.20 ± 50.54) and SiC (878.16 ± 29.81), while the lowest fatigue strength for 20%Si (773.89 ± 46.44) and AlOx (796.70 ± 46.48). Topography analysis depicted similar surface morphology for all conditions. However, roughness (μm) was only statistically different between 7%Si (Ra = 0.30 ± 0.09; Rz = 2.31 ± 0.63) and SiC (Ra = 0.26 ± 0.04; Rz = 1.99 ± 0.34). Monoclinic phase grains appeared on Y-TZP surface in a similar content (≈11–12%) for the protocols. Fractography showed all failures starting on air-abraded surface/sub-surface defects from the tensile side. In terms of roughness, phase transformation and fatigue, the new 7% silica-coated aluminum oxide presented similar behavior to the commercially available powder. Increasing silica-coating concentration to 20% did not lead to a gentle air-abrasion protocol. •7% silica-coating experimental material showed to be an adequate alternative for air-abrasion treatment.•The increase of silica-coating concentration to 20% did not lead to a gentle protocol.•Air-abrasion with aluminum oxide and 20% silica-coating led to the worst fatigue performance.