Effect of Sintering Time and Temperature on Various Properties of Monolithic Translucent Zirconium Oxide Ceramic
Kamal Khaled Ebeid Ahmed;
Abstract
This study was designed to evaluate the effect of different sintering times and temperatures on the color reproduction, translucency, surface roughness, biaxial flexural strength and surface hardness of monolithic translucent zirconia.
Ninety disc shaped specimens having 15mm diameter and 1mm thickness were milled using a Datron milling machine from Bruxzir translucent zirconia blanks with the shade A3. Specimens were divided into three groups (n=30) according to the sintering temperature (1460°C, 1530°C, 1600°C) and each group was later subdivided into three subgroups (n=10) according to the sintering time (2, 7, 9 hours).
E was obtained for the specimens after measuring the CIELAB coordinates for each disc using a Vita Easyshade spectrophotometer and comparing the outcome to the standard coordinates of the shade A3.
The contrast ratio (CR) was calculated for each specimen to assess translucency after obtaining the CIELAB coordinates when backed with a white and black background. This ratio tends toward unity for opaque materials and toward zero for transparent materials.
A Keyence VX-100 3D laser microscope was used to scan the discs surface and measure the surface roughness.
Three specimens from each subgroup were analyzed using X-ray diffraction to detect the ZrO2 crystalline phases available. Specimens were subject to Cu K alpha radiation with a range of 20°-40°, step size of 0.02° and the scan time per step was 10 seconds.
The biaxial flexural strength test was performed using piston-on-three balls technique according to the ISO 6872 specifications. A Zwick universal testing machine was used to conduct the test and the fracture load was used to calculate the biaxial flexural strength in MPa.
Vickers surface hardness test was performed using a Zwick hardness testing machine on the broken samples. A load of 5kg was applied using the indenter on the specimens for a period of 10 seconds and the indentation was observed under a magnification of 20X.
Results were tabulated and statistically analyzed using two-way ANOVA and Tukeys HSD post hoc test. Statistical analysis revealed a significant decrease in the E and the CR as the sintering time and temperature increased. No significant changes were observed among the groups regarding the surface roughness, biaxial flexural strength and surface hardness. Regarding the XRD analysis, all of the tested samples showed only tetragonal phase characteristic peaks.
Ninety disc shaped specimens having 15mm diameter and 1mm thickness were milled using a Datron milling machine from Bruxzir translucent zirconia blanks with the shade A3. Specimens were divided into three groups (n=30) according to the sintering temperature (1460°C, 1530°C, 1600°C) and each group was later subdivided into three subgroups (n=10) according to the sintering time (2, 7, 9 hours).
E was obtained for the specimens after measuring the CIELAB coordinates for each disc using a Vita Easyshade spectrophotometer and comparing the outcome to the standard coordinates of the shade A3.
The contrast ratio (CR) was calculated for each specimen to assess translucency after obtaining the CIELAB coordinates when backed with a white and black background. This ratio tends toward unity for opaque materials and toward zero for transparent materials.
A Keyence VX-100 3D laser microscope was used to scan the discs surface and measure the surface roughness.
Three specimens from each subgroup were analyzed using X-ray diffraction to detect the ZrO2 crystalline phases available. Specimens were subject to Cu K alpha radiation with a range of 20°-40°, step size of 0.02° and the scan time per step was 10 seconds.
The biaxial flexural strength test was performed using piston-on-three balls technique according to the ISO 6872 specifications. A Zwick universal testing machine was used to conduct the test and the fracture load was used to calculate the biaxial flexural strength in MPa.
Vickers surface hardness test was performed using a Zwick hardness testing machine on the broken samples. A load of 5kg was applied using the indenter on the specimens for a period of 10 seconds and the indentation was observed under a magnification of 20X.
Results were tabulated and statistically analyzed using two-way ANOVA and Tukeys HSD post hoc test. Statistical analysis revealed a significant decrease in the E and the CR as the sintering time and temperature increased. No significant changes were observed among the groups regarding the surface roughness, biaxial flexural strength and surface hardness. Regarding the XRD analysis, all of the tested samples showed only tetragonal phase characteristic peaks.
Other data
| Title | Effect of Sintering Time and Temperature on Various Properties of Monolithic Translucent Zirconium Oxide Ceramic | Other Titles | تاثير زمن و حرارة التلبد على مختلف خصائص خزفيات أكسيد الزركونيوم الشافه المتآلفة | Authors | Kamal Khaled Ebeid Ahmed | Issue Date | 2014 |
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