Effect of calcination on minimally processed recycled zirconia powder derived from milling waste

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Strazzi-Sahyon, H. B. ; Campos, T. M. B. ; dos Santos, C. ; Piza, M. M. T. ; Alves, L. M. M. ; Jalkh, E. B. Benalcazar ; Bergamo, E. T. P. ; Tebcherani, S. M. ; Witek, L. ; Coelho, P. G. ; Yamaguchi, S. ; Bonfante, E. A.

• Document type: Journal article
• Source: Dental Materials; v. 40, n. 9, p. 10-pg., 2024-08-14.

Abstract

Objective: To assess the influence of calcination process on the properties of minimally processed recycled 3Y-TZP, and to compare it with its commercial counterpart. Methods: Non-milled 3Y-TZP waste was collected, fragmented and ball-milled to a granulometric < 5 <mu>m. Half of the recycled powder was calcined at 900 degrees C. Recycled 3Y-TZP disks were uniaxially pressed and sintered to create two recycled groups: 1) Calcined and 2) Non-calcined to be compared with a commercial CAD/CAM milled 3Y-TZP. The microstructure of experimental groups was assessed through density (n = 6), scanning electron microscopy (n = 3) and energy-dispersive X-ray spectroscopy (n = 3); and the crystalline content was evaluated through X-ray diffraction (XRD) (n = 3). Optical and mechanical properties were investigated through reflectance tests (n = 10), and Vickers hardness, fracture toughness (n = 5), and biaxial flexural strength tests (n = 16), respectively. Fractographic analysis was performed to identify fracture origin and crack propagation. Statistical analyses were performed through ANOVA followed by Tukey<acute accent>s test, and by Weibull statistics. Results: Particle size distribution of recycled powder revealed an average diameter of similar to 1.60 mu m. The relative density of all experimental groups was > 98.15 % and XRD analysis exhibited a predominance of tetragonal-phase in both recycled groups, which were similar to the crystallographic pattern of the control group. Cross-section micrographs presented flaws on the non-calcined group, and a more homogeneous microstructure for the calcined and commercial groups. Commercial samples showed lower contrast-ratio and higher translucency-parameter than the recycled groups, where non-calcined presented higher translucency-parameter and lower contrast-ratio than its calcined counterpart. The commercial group presented higher fracture toughness and characteristic strength than the recycled groups. Moreover, the calcined group exhibited higher hardness, characteristic strength, and probability of survival at higher loads than the non-calcined group. Fractographic analysis depicted the presence of microstructural flaws in the non-calcined group, which may have acted as stress-raisers and led to failures at lower flexural strengths values. Significance: The calcination process improved the microstructure, optical, and mechanical properties of the recycled 3Y-TZP. (AU)

• FAPESP's process: 21/07440-2 - Graduated glass infiltration in an ultra-translucent zirconia (5Y-PSZ): synthesis, processing and characterization of physical and mechanical properties
• Grantee: Larissa Marcia Martins Alves
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 21/06730-7 - Towards sustainable zirconia recycled from milling waste and boosted by glass infiltration for restorative use, and of the development of strong, graded, and aging resistant multilayered zirconia blocks
• Grantee: Estevam Augusto Bonfante
• Support Opportunities: Research Grants - Young Investigators Grants - Phase 2
• FAPESP's process: 16/18818-8 - Multi-User Equipment approved in grant 2012/19078-7: ElectroPuls E3000 Linear-Torsion All-Electric dynamic test instrument package
• Grantee: Estevam Augusto Bonfante
• Support Opportunities: Multi-user Equipment Program
• FAPESP's process: 20/12874-9 - Infiltration graded by glass in an experimental composite based on whiskers of alumina and zircônia: development, microstructural characterization and optical and mechanical properties
• Grantee: Tiago Moreira Bastos Campos
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 19/08693-1 - Experimental glass-infiltrated alumina-zirconia composites: characterization of microstructure, optical and mechanical properties.
• Grantee: Edmara Tatiely Pedroso Bergamo
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 22/12118-5 - Development of the recycling process of 3Y-TZP and application in the production of composites with elastic module gradients
• Grantee: Henrico Badaoui Strazzi Sahyon
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 22/07157-1 - Physical and mechanical characterization of a multilayered system using recycled zirconia
• Grantee: Ernesto Byron Benalcazar Jalkh
• Support Opportunities: Scholarships in Brazil - Post-Doctoral