添加剂对Y-TZP烧结及力学性能影响

通过在Ｙ－ＴＺＰ中加入少量的添加剂,使得材料的烧结温度明显降低,并且制备出具有较细晶粒的Ｙ－ＴＺＰ材料,添加剂所形成的玻璃相主要存在于３个晶粒所形成的三角区内,在Ｙ－ＴＺＰ中加入少量的添加剂后,尽管得到的晶粒尺寸较小,但当材料发生断裂时,仍可使一些四方相氧化锆发生Ｍａｒｔｅｎｓｉｔｅ相变转变为单斜相,并使材料仍具有较高的抗折强度和断裂韧性。     

3Y-TZP材料的液相烧结

通过在3Y-TZP(Tetragonal Zirconia Polycrystals stabilized with 3mol% Y2O3)中加入适当含量的硅酸盐玻璃添加剂,使其烧结温度明显降低,并且制备出具有细晶粒、高强度的四方相氧化锆增韧陶瓷材料.本文分析了添加剂对3Y-TZP材料烧结特性及显微结构的影响.发现液相烧结的3Y-TZP具有良好的抗弯强度,但韧性有待于提高.     

Al2O3/Y-TZP复相陶瓷的力学性能及耐磨性

通过常压烧结制备了Al2O3/Y-TZP复相陶瓷,研究了Al2O3含量对材料力学性能及耐磨性的影响。体积分数为35%Al2O3的Al2O3/Y-TZP复相陶瓷具有相对高的韧性(12.5MPa·m1/2)和较低的磨损率(9.2×10-6mm3/(m·N))。     

烧结法制备Y-TZP/微晶玻璃复合材料的研究

用烧结法制备了Y-TZP，微晶玻璃复合材料，结合DTA分析制定了热处理制度，研究了烧结温度和Y-TZP的加入对复合材料力学性能的影响。     

超塑性Y-TZP增韧陶瓷超细粉末的研究

用化学共沉淀法制备了3mol％Y_2O_3-ZrO_2超细粉末。利用热分析,x射线,透射电镜,颗粒粒度分析仪分析了粉料的相组成;颗粒形貌、大小;粉料的团聚状态;化学组成的均一性以及其烧结性能,并结合烧结试样的显微结构和力学性能对粉末的性能做出了评价。实验表明,所制备的粉料组成较为均匀;粒度分布窄;团聚体尺寸小,烧结活性高;颗粒粒度约为200(?)。粉料的相组成主要为四方相和约26％的单斜相。3Y-TZP陶瓷材料三点弯曲强度达1479.14MPa,断裂韧性为13.2MPa·m~(1/2),超塑性压缩变形达190％。     

纳米3Y-TZP粉体的制备及烧结曲线研究

采用共沉淀法制备纳米3Y-TZP粉体,并利用DSC-TG,XRD和TEM等测试方法对3Y-TZP的物理化学性能进行表征。通过研究纳米3Y-TZP粉体的烧结曲线,分析3Y-TZP素坯在烧结过程的致密化和显微结构。结果表明:在600℃下煅烧2h后,可获得晶粒尺寸为13nm,晶形发育良好、团聚较少的纳米3Y-TZP粉体。在烧结过程中,不同烧结阶段中的扩散机制不同,在烧结后期晶粒尺寸发生显著长大。     

液相烧结 3Y-TZP 陶瓷的相组成与力学性能

以 CaO-MgO-SiO2 玻璃为烧结助剂,用液相烧结法制备了物质的量分数为 3% 氧化钇稳定四方氧化锆陶瓷(3Y-TZP).研究了烧结助剂对材料致密化、显微结构、相组成及力学性能的影响.结果表明:烧结助剂的引人显著降低了材料的烧结温度,使材料具有细晶显微结构,并对材料的相组成产生影响,同时也使材料具有良好的力学性能.材料的力学性能主要与其致密化程度有关,在最佳条件下,材料的抗弯强度和断裂韧性可分别达到 691MPa 和6.6MPa·m1/2.     

Y-TZP/微晶玻璃牙科复合材料的物相和性能研究

采用烧结法制备了Y -TZP/微晶玻璃牙科复合材料。本文主要研究了不同烧结温度 ,Y -TZP的含量对复合材料物相组成和性能的影响。当烧结温度达到 110 0℃时 ,复合材料中的Y -TZP开始和微晶玻璃中的SiO2反应生成ZrSiO4,并且有大部分t-ZrO2 转变为m -ZrO2 。提高烧结温度可以增大复合材料的抗弯强度 ,但烧结温度超过 10 5 0℃以后 ,抗弯强度会随温度的升高而降低。Y -TZP起到了提高材料强度的作用。     

添加Al2O3的Y-TZP基陶瓷材料研究及其应用前景

介绍了Y-TZP材料中引入Al2O3后,Al2O3对Y-TZP材料的烧结性、力学性能及老化性能的影响.简述了Al2O3/Y-TZP材料的显微结构分析及其韧性变化的理论估计.此种材料有广阔的应用前景.     

钇稳定四方氧化锆精细陶瓷老化性能检测方法的研究

钇稳定四方氧化锆(Y-TZP)精细陶瓷依靠钇掺杂来稳定四方相结构,在实际应用中,特别是在潮湿环境1000 ℃以上的中低温区,长期使用时由于发生四方相向单斜相的转变,而表现出老化现象.因此Y-TZP这类重要精细陶瓷的可靠性及失效分析的关键是其低温老化性能的检测和分析.在对Y-TZP老化性能研究中,通过设定温度、时间、气氛等参数,对氧化锆陶瓷样品进行老化实验.然后通过实验前后对样品称重,X射线粉末衍射仪进行物相分析等手段,对老化样品进行分析,从而了解在老化条件下对氧化锆陶瓷材料的样品表面相结构影响,分析氧化锆陶瓷材料的老化机理.通过多种检测分析方法的对比研究,确定XRD相定量分析是一种可靠、可行、高效、准确的Y-TZP老化性能检测分析手段.     

热压Y－TZP的超塑性压缩变形特性

研究了热压法制备的Ｙ２Ｏ３稳定的四方ＺｒＯ２多晶体（Ｙ－ＴＺＰ）在单轴压缩试验中的超塑性变形特性。结果表明热压Ｙ－ＴＺＰ可以超塑性压缩变形至－１．３０。讨论了应变速率和温度对超塑性变形的影响。本试验中最佳变形条件为温度１４５０～１５５０℃，初始应变速率ε＝１０－４～１０－５Ｓ－１。研究了变形前后试样的显微结构的变化。     

Y—TZP陶瓷材料的近期研究动态

本文综述了近年来Ｙ２Ｏ３稳定的四方氧化锆多晶体（ＴＺＰ）材料的发展情况。主要岂以下四方面来叙述：（１）原料和制备工艺：（１）组成优化和低温烧结；（３）换制低温老化和改善高温力学性能；（４）耐磨性。     

超塑性Y－TZP陶瓷拉伸变形研究

研究了超塑性Ｙ－ＴＺＰ陶瓷拉伸变形，结果表明，超塑性Ｙ－ＴＺＰ在１４５０℃，初始应变速率ε＿０为１０￣（－４）～１０￣（－５）ｓ￣（－１）条件下拉伸变形量达到２４０％，而应变速率敏感性指数ｍ＝０．４２。实验是在气氛为空气的炉中进行的，冷却到常温后测定试件的伸长量。对超塑性变形前后的试件进行了显微结构观察。     

Low temperature degradation of laser patterned 3Y-TZP: Enhancement of resistance after thermal treatment

The aim of this study is to characterize the resistance to low temperature degradation (LTD) of the surface of dental-grade zirconia (3Y-TZP) patterned with a Nd:YAG laser (532 nm harmonic and pulse duration of 10 ns) employing an interference setup.Laser patterning decreases the resistance to LTD of 3Y-TZP because of the presence of monoclinic phase and residual stresses, induced by the thermal shock during laser-material interaction. A thermal treatment (1 h at 1200 °C) anneals the affected microstructure and increase the resistance to LTD of laser patterned 3Y-TZP. Transformation delay may be attributed to monoclinic phase reversion, texture in the tetragonal phase and the existence of a net of shallow microcracks on the surface, accommodating autocatalytic transformation.     

Fabrication and high-temperature properties of Y-TZP ceramic helical springs by a gel-casting process

A rectangular cross-section ceramic helical spring of yttria-stabilized tetragonal zirconia polycrystals (Y-TZP) was prepared by the gel-casting process. Both the compressive curves and comprehension rebound curves were tested at room temperature and high temperature. The results showed that springs obeyed Hooke׳s Law at room temperature, as the compression resilience ratio of the samples was nearly 100% under the condition of spring׳s security and no damping loss occurred during the process. Besides, mechanical failures of springs occurred under loads around 128 N with the deformation of 10%. With increasing test temperature the maximum load-carrying capacity of the spring decreased, while the maximum deformation increased. Besides, the load–compression curve showed a yield step when the test temperature was above 800 °C. At elastic stage of spring under high temperature, the compression resilience ratio was also nearly 100%; however, the anelastic effect took place and energy loss increased with the increase in test temperature.     

Assessment of low-temperature degradation of Y-TZP ceramics based on Raman-spectroscopic analysis and hardness indentation

This paper focuses on the analysis of hydrothermally induced phase transformation of yttria-stabilized tetragonal polycrystalline zirconia (Y-TZP) and its influence on the hardness. Due to the hydrothermal exposure and the accompanied low-temperature degradation (LTD), a micro-cracked transformation zone is generated at the surface and progresses into the subjacent material. Raman-spectroscopic analysis of hydrothermally loaded and cross-sectioned samples revealed complete phase transformation within this zone. Its depth as well as its temperature-dependent growth rate was verified. Raman-spectroscopic measurements at the surfaces were correlated with the progression of the transformation zone. An efficient model, which assumes one extinction coefficient for tetragonal and monoclinic microstructure, enables to determine the depth of the transformation zone from the measured Raman signals. Furthermore, an exponentially decreasing Vickers hardness with increasing depth was determined. Finally, a differently sintered Y-TZP ceramic revealed enhanced resistance against LTD for the same hydrothermal loading conditions.     

Oral degradation of Y-TZP ceramics

The aim of this work was to study the degradation of yttria-stabilized tetragonal zirconia (Y-TZP) directly exposed to the oral environment. Four groups of Y-TZP were tested G1: TZ-PX-242A, Zpex^®; G2: TZ-PX-357, Zpex Yellow^®; G3: ProtMat^®, and G4: LAVA Frame^®. The samples were attached to the base of temporary full dentures of patients and aged for 100 days. In this way, one surface of the samples was exposed to the oral environment. The samples (25?×?2?×?1.5?mm) were cut from noncommercial (G1 and G2) and commercially available (G3 and G4) presintered zirconia blocks. Quantitative and qualitative analyses were performed by X-ray fluorescence (XRF). Microstructural characterization was performed by scanning electron microscopy (SEM), X-ray diffraction (XRD), 3D surface roughness measurements and grain size measurements. The mechanical properties were determined by a four-point bending test. The data were analyzed by one-way ANOVA (p?≤?0.05), Tukey's test and Weibull analysis. The results showed a tetragonal-monolithic transformation in the zirconia after oral aging. The surface roughness increased in all groups, and groups G3 and G4 showed increases in their flexural strengths.     

A review on the hydrothermal ageing behaviour of Y-TZP ceramics

The state of understanding on the devastating effects of hydrothermal ageing on the properties of yttria-tetragonal zirconia polycrystal (Y-TZP) when exposed to humid environment are reviewed. The prime factors governing the ageing-induced tetragonal to monoclinic phase transformation include the tetragonal grain size, sintering techniques particularly two-step sintering, microwave sintering and electric field assisted sintering, and yttria content are discussed. In addition, the beneficial effects of sintering additives or dopants in promoting sintering as well as suppressing the ageing-induced monoclinic formation are also deliberated. Selective dopants and co-dopants such as copper oxide, alumina, iron oxide and magnesium oxide were found to be beneficial in suppressing hydrothermal ageing in zirconia. Other important boundary conditions to be considered when evaluating the ageing behaviour of Y-TZP includes the ageing environment i.e. temperature, medium and applied pressure which were discovered to have an impact on the rate of phase transformation. Furthermore, the effects of ageing-induced monoclinic formation on the surface topography and mechanical properties of Y-TZP are reviewed. This review indicated that the ageing of Y-TZP can be rather intricate as there are many combinatory factors that needs to be tailored in order to develop an ageing-resistant zirconia without compromising on the transformation toughening effect and other properties.     

Effect of 1-D and 2-D carbon-based nano-reinforcements on the dry sliding-wear behaviour of 3Y-TZP ceramics

The dry sliding-wear behaviour of a zirconia doped with 3 mol% yttria (3Y-TZP) monolithic and of two 3Y-TZP composites, these latter with the same ultrafine-grained microstructure as the former but reinforced with either 1-D carbon nanofibres (CNFs) or 2-D reduced graphene oxide (rGO) nanoplatelets, was evaluated by ball-on-disk tests at moderate load, and compared critically. It was found that 3Y-TZP, 3Y-TZP/CNFs, and 3Y-TZP/rGO undergo mild wear, in the three cases by abrasion with contributions from both plastic deformation and fracture (with varying severities depending on the sample). It was also found that wear resistance does not correlate with hardness or toughness, but with whether or not there is formation of self-lubricating tribofilms on the contact surface. Specifically, once pulled-out, 2-D rGO nano-reinforcements impose solid-state lubrication that reduces the coefficient of friction (CoF), thus providing 3Y-TZP/rGO with superior wear resistance relative to both 3Y-TZP and 3Y-TZP/CNFs. 1-D CNF nano-reinforcements, however, do not form such tribofilms, or hardly do so, thus having no effect on the CoF and wear resistance. Implications are discussed of both the dimensionality of the carbon-based nano-reinforcements and the testing conditions for the microstructural design of ceramic composites for tribological applications.