Objectives

To characterize the optical and mechanical properties of a commercial and in-house translucent Y-TZP before and after aging in autoclave or hydrothermal reactor.

Methods

In-house experimental discs were obtained through uniaxial and isostatic pressing a translucent Y-TZP powder and sintering at 1,550 °C/1 h. Commercial discs were milled from pre-sintered blocks fabricated with the same powder through uniaxial and isostatic pressing and sintering. Discs were allocated into three groups according to aging condition: immediate, aged via autoclave, or reactor (134 °C, 20 h, 2.2 bar). Crystalline content and microstructure were evaluated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Residual compressive stress (CS) was determined by Raman spectroscopy. Optical properties were determined by the contrast ratio (CR) and translucency parameter (TP) using reflectance data. Mechanical properties were assessed by Vickers hardness, fracture toughness and biaxial flexural strength tests.

Results

XRD and SEM revealed a typical Y-TZP crystalline content, chiefly tetragonal phase, and a dense crystalline matrix for both processing protocols. Reactor aging triggered a more pronounced t-m transformation relative to autoclave. In-house and commercial Y-TZPs demonstrated similar CR and TP, with reactor aging significantly increasing their translucency. Similarly, reactor aging influenced Vickers hardness and fracture toughness. In-house processed Y-TZP clearly demonstrated the presence of CS, whereas commercial Y-TZP showed no presence of CS. Non-aged in-house Y-TZP resulted in significantly lower characteristic strength relative to commercial Y-TZP. While aging protocols significantly increased the characteristic strength of in-house Y-TZP, reactor significantly decreased commercial Y-TZP characteristic strength. Both Y-TZP processing protocols demonstrated high reliability at high-stress missions, with no detrimental effect of aging.

Conclusions

Laboratory aging methodology significantly influenced optical and mechanical properties of a commercial and in-house translucent Y-TZP.

中文翻译：

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水热降解方法影响半透明氧化锆的性质和相变深度。

目标

表征商用和内部半透明Y-TZP在高压釜或水热反应器中老化前后的光学和机械性能。

方法

通过单轴和等静压半透明的Y-TZP粉末并在1,550°C / 1 h烧结获得内部实验盘。通过单轴，等静压和烧结，从用相同粉末制成的预烧结块中研磨出商用圆盘。根据老化条件，将圆盘分为三组：即刻，通过高压釜或反应器（134°C，20 h，2.2 bar）老化。使用X射线衍射（XRD）和扫描电子显微镜（SEM）评估晶体含量和微观结构。通过拉曼光谱法测定残余压应力（CS）。使用反射率数据通过对比度（CR）和半透明参数（TP）确定光学特性。机械性能通过维氏硬度，断裂韧性和双轴弯曲强度测试进行评估。

结果

XRD和SEM揭示了两种处理方案的典型Y-TZP晶体含量，主要是四方相和致密的晶体基质。反应堆老化引发更明显的TM相对于高压灭菌器的转化。内部和商业Y-TZP表现出相似的CR和TP，反应堆的老化大大提高了其半透明性。同样，反应堆的老化也会影响维氏硬度和断裂韧性。内部加工的Y-TZP清楚地表明了CS的存在，而商业Y-TZP则没有了CS的存在。与商用Y-TZP相比，未老化的内部Y-TZP导致特征强度明显降低。虽然老化方案显着增加了室内Y-TZP的特征强度，但反应堆显着降低了商业Y-TZP的特征强度。两种Y-TZP处理协议在高压力任务中均显示出高可靠性，并且没有老化的有害影响。

结论

实验室老化方法极大地影响了商业和内部半透明Y-TZP的光学和机械性能。