IADR Abstract Archives
Effect of Surface Finishing Assessed by Quantitative and Qualitative Fractography
Objectives: The aim of the present study was to evaluate the influence of surface finishing in three resin-based composits (RBC) on the result of a 3-point bending test using quantitative and qualitative fractography as well as microstructural characteristics.
Methods: 270 rectangular specimens (n=30) of three RBCs (Table 1) were prepared, stored and tested according to ISO 4049:2009. Prior testing, the samples were subjected to three surface treatments: 1) no treatment (oxygen inhibition layer was preserved), 2) wet-ground with SiC abrasive paper P1200 and 3) polishing up to P4000. A three-point bending test was followed by quantitative and qualitative fractography, surface roughness and SEM analysis. The mirror radius that runs in the direction of constant stress was used to calculate the mirror constant (A) using Orr’s equation. Statistical analysis was performed using multifactorial ANOVA, Tukey’s post hoc test, and Weibull analysis.
Results: The inorganic filler amount has a direct impact on FS and E. Surface finishing influenced less the fracture mode. Failures initiated by volume defects were the most common failure mode (77.4%) with surface defects accounting for 14.9% (edge) and 7.7% (corner). Polishing resulted in comparable or slightly lower roughness compared to no treatment, both 7-8 times lower compared to the P1200 treatment. The increase in roughness within the analyzed range did not lead to an increase in surface-related failures. Within the analyzed roughness range, there is no direct influence of surface finishing on the measured mechanical parameters.
Conclusions: The clear dominance of volume defects in all examined materials as a cause of material failure reduces the influence of roughness on the measured properties. This insight was only possible using qualitative and quantitative research fractography.
Methods: 270 rectangular specimens (n=30) of three RBCs (Table 1) were prepared, stored and tested according to ISO 4049:2009. Prior testing, the samples were subjected to three surface treatments: 1) no treatment (oxygen inhibition layer was preserved), 2) wet-ground with SiC abrasive paper P1200 and 3) polishing up to P4000. A three-point bending test was followed by quantitative and qualitative fractography, surface roughness and SEM analysis. The mirror radius that runs in the direction of constant stress was used to calculate the mirror constant (A) using Orr’s equation. Statistical analysis was performed using multifactorial ANOVA, Tukey’s post hoc test, and Weibull analysis.
Results: The inorganic filler amount has a direct impact on FS and E. Surface finishing influenced less the fracture mode. Failures initiated by volume defects were the most common failure mode (77.4%) with surface defects accounting for 14.9% (edge) and 7.7% (corner). Polishing resulted in comparable or slightly lower roughness compared to no treatment, both 7-8 times lower compared to the P1200 treatment. The increase in roughness within the analyzed range did not lead to an increase in surface-related failures. Within the analyzed roughness range, there is no direct influence of surface finishing on the measured mechanical parameters.
Conclusions: The clear dominance of volume defects in all examined materials as a cause of material failure reduces the influence of roughness on the measured properties. This insight was only possible using qualitative and quantitative research fractography.
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