Effect of ceramic density and curing pressure on properties of a resin infused alumina
Jokhadar, Hossam Faisal
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OBJECTIVES: To investigate the effect of sintering temperature on the microstructure and density of resin infused alumina, to investigate effect of sintering temperature and curing pressure on flexural strength, surface roughness, Young’s modulus, hardness and fracture toughness of resin infused alumina. MATERIALS: Alumina infused polymer and Vita In-ceram alumina. METHODS: Alumina powders were dry-pressed in a stainless steel mold to produce cylindrical alumina blocks. Blocks were divided into four different groups sintered at four different temperatures (1050ºC,1150ºC,1200ºC,1250ºC). The density of each block was measured. They were silane treated, and then infused with a UDMA mixture under vacuum condition. Infused alumina blocks were cured with an Isopress machine at two different pressures (20,001 psi and 23,187 psi) then cut into discs 1.5 mm thick x 14 mm diameter, n=8 for each group. Biaxial flexural strength was measured using an Instron Universal Testing machine at 0.5 mm/min crosshead speed. Surface roughness was measured with a Mitotoyu profilometer. Hardness was measured using a Vickers hardness test using Instron-produced indentations at 15 newton load for 30 seconds. Young’s modulus was measured by compressive Young’s modulus method using the Instron machine at 0.5 mm/min crosshead speed. Fracture toughness was measured using the Vickers indentation fracture toughness test. Microstructure of each group was investigated with a scanning electron microscope (SEM). RESULTS: Data were analyzed with One-way ANOVA with Tukey-Kramer HSD for comparison of all pairs at p<0.05 was used to determine statistical difference between groups. CONCLUSION: The biaxial flexural strength, surface toughness, hardness, Young’s modulus and fracture toughness increase as density of resin infused alumina increases. Interpenetrating phase material provides greater biaxial flexural strength and fracture toughness than single-phase alumina ceramics. Curing pressure has a significant effect on the biaxial flexural strength of polymer infused alumina blocks.