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 µm. Half of the recycled powder was calcined at 900 °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´s test, and by Weibull statistics.
RESULTS: Particle size distribution of recycled powder revealed an average diameter of ∼1.60 µm. 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.
CONCLUSIONS: The calcination process improved the microstructure, optical, and mechanical properties of the recycled 3Y-TZP.
METHODS: Non-milled 3Y-TZP waste was collected, fragmented and ball-milled to a granulometric < 5 µm. Half of the recycled powder was calcined at 900 °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´s test, and by Weibull statistics.
RESULTS: Particle size distribution of recycled powder revealed an average diameter of ∼1.60 µm. 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.
CONCLUSIONS: The calcination process improved the microstructure, optical, and mechanical properties of the recycled 3Y-TZP.
摘要：
目的：为了评估煅烧过程对最小处理的回收3Y-TZP性能的影响，并将其与商业对应物进行比较。
方法：收集未研磨的3Y-TZP废物，破碎并球磨至粒度<5µm。一半的回收粉末在900°C下煅烧。将回收的3Y-TZP圆盘单轴压制并烧结以产生两个回收组：1）煅烧和2）未煅烧，以与商业CAD/CAM研磨的3Y-TZP进行比较。通过密度（n=6）评估实验组的微观结构，扫描电子显微镜（n=3）和能量色散X射线光谱（n=3）；并通过X射线衍射（XRD）（n=3）评估结晶含量。光学和机械性能进行了研究，通过反射试验（n=10），和维氏硬度，断裂韧性（n=5），和双轴弯曲强度试验(n=16)，分别。进行了分形分析以确定断裂起源和裂纹扩展。通过方差分析进行统计分析，然后进行Tukey检验。和威布尔统计。
结果：回收粉末的粒度分布显示平均直径为1.60µm。所有实验组的相对密度>98.15%，XRD分析显示，在两个回收组中，四方相占主导地位。与对照组的晶体学模式相似。横截面显微照片显示了未煅烧基团的缺陷，以及煅烧和商业组的更均匀的微观结构。与回收组相比，商业样品显示出较低的对比度和较高的半透明参数，其中非煅烧比其煅烧对应物呈现更高的半透明参数和更低的对比度。商业组表现出比回收组更高的断裂韧性和特征强度。此外，煅烧组表现出更高的硬度，特征强度,以及在比未煅烧组更高的负荷下存活的概率。分形分析描绘了未煅烧组中微观结构缺陷的存在，这可能起到了应力增加的作用，并导致在较低的抗弯强度值下失效。
结论：煅烧过程改善了微观结构，光学，和力学性能的回收3Y-TZP。
方法：收集未研磨的3Y-TZP废物，破碎并球磨至粒度<5µm。一半的回收粉末在900°C下煅烧。将回收的3Y-TZP圆盘单轴压制并烧结以产生两个回收组：1）煅烧和2）未煅烧，以与商业CAD/CAM研磨的3Y-TZP进行比较。通过密度（n=6）评估实验组的微观结构，扫描电子显微镜（n=3）和能量色散X射线光谱（n=3）；并通过X射线衍射（XRD）（n=3）评估结晶含量。光学和机械性能进行了研究，通过反射试验（n=10），和维氏硬度，断裂韧性（n=5），和双轴弯曲强度试验(n=16)，分别。进行了分形分析以确定断裂起源和裂纹扩展。通过方差分析进行统计分析，然后进行Tukey检验。和威布尔统计。
结果：回收粉末的粒度分布显示平均直径为1.60µm。所有实验组的相对密度>98.15%，XRD分析显示，在两个回收组中，四方相占主导地位。与对照组的晶体学模式相似。横截面显微照片显示了未煅烧基团的缺陷，以及煅烧和商业组的更均匀的微观结构。与回收组相比，商业样品显示出较低的对比度和较高的半透明参数，其中非煅烧比其煅烧对应物呈现更高的半透明参数和更低的对比度。商业组表现出比回收组更高的断裂韧性和特征强度。此外，煅烧组表现出更高的硬度，特征强度,以及在比未煅烧组更高的负荷下存活的概率。分形分析描绘了未煅烧组中微观结构缺陷的存在，这可能起到了应力增加的作用，并导致在较低的抗弯强度值下失效。
结论：煅烧过程改善了微观结构，光学，和力学性能的回收3Y-TZP。
