（Ce—TZP）—Al2O3陶瓷力学性能及其增韧机理的研究

本文研究了不同Al2O_3含量对(Ce-TZP)-Al_2O_3陶瓷强度、硬度及断裂韧性的影响。结果表明:Al_2O_3含量在10—20wt%时,具有明显的增强效果,较大幅度地提高了硬度及强度,并保留较高的韧性。借助于磨损试验和X射线衍射分析,研究了Ce-TZP材料的增韧机理。结果表明:材料的磨损抗力与磨损面上单斜相增量呈一致增加的关系。可以认为,该材料的增韧以相变增韧为主要机制。     

ZrO2—Al2O3系陶瓷复合材料力学性质

本文研究了ZrO_2-Al_2O_3系统陶瓷复合材料的力学性质,发现有两个最佳区域存在:在Al_2O_3基的陶瓷中,添加第二相ZrO_2颗粒可以使Al_2O_3瓷得到增韧和强化;在ZrO_2基的陶瓷中,添加少量Al_2O_3则可以通过Al_2O_3晶粒的裂纹弯曲和分叉增韧,强化ZrO_2的相变增韧,使ZrO_2瓷的强度和断裂韧性得到进一步的提高。适宜地控制YMSZ(Y_2O_3亚稳定ZrO_2)中Y_2O_3和TZP(四方相氧化锆多晶瓷)中的Al_2O_3量,可以获得高韧性和高强度的ZrO_2-Al_2O_3系陶瓷复合材料。     

Al2O3—TiB2陶瓷刀具材料的研制及其耐磨性能研究

本文研制成功了一种新型陶瓷刀具材料即Al_2O_3-Ti B_2陶瓷刀具材料。文中讨论了该材料的研制方法,力学性能和微观结构特点,并对该材料的磨损行为和磨损机理进行了研究。结果表明:Ti B_2粒子的弥散可以明显提高该材料的耐磨性。加工淬火钢时该材料的抗磨损能力明显优于Al_2O_3-TiC陶瓷刀具材料。Al_2O_3-Ti B_2陶瓷刀具材料的磨损过程主要受粘着、耕犁和微破损机制的控制。     

ZrO2增韧Al2O3／SiCnano复合陶瓷的力学性能及微结构

本文对Al_2O_3/SiC nano ZrO_2(3Y)复相陶瓷的力学性能和微结构进行了研究,探讨了ZrO_2(t)应力诱导相交增韧机制和纳米粒子增韧机制相互迭加的可能性。结果表明:适量的第二相纳米粒子ZrO_2(3Y)加入对材料的微结构有很大影响,同时对材料的力学性能的提高作出贡献。     

MgO含量对Al_2O_3/ZrO_2/莫来石复相陶瓷性能的影响

采用ZrSiO_4和Al_2O_3为原料,通过无压烧结法制备了不同MgO含量的Al_2O_3/Zr O_2/莫来石复相陶瓷,研究了复合陶瓷的显微组织、弯曲强度、断裂韧性和抗热震性能。结果表明:添加MgO有利于ZrO_2四方相的稳定,从而提高了陶瓷的弯曲强度、断裂韧性和抗热震性。MgO添加量为4%时,Al_2O_3/ZrO_2/莫来石复相陶瓷的弯曲强度达到最大值365 MPa,陶瓷的断裂韧性达到5.31 MPa·m~(1/2)。复相陶瓷热震后强度的损失率仅为5.61%。     

Al_2O_3含量对ZrO_2/Al_2O_3复相陶瓷流变性能和抗弯强度的影响

采用有机泡沫浸渍法制备ZrO_2/Al_2O_3复相陶瓷,分析Al_2O_3添加量对泡沫陶瓷显微形貌、相结构、抗弯强度和浆料流变性能的影响,确定制备复相陶瓷的最佳工艺参数。实验结果表明,ZrO_2/Al_2O_3复相陶瓷由m-ZrO_2相、t-ZrO_2相和Al_2O_3相组成;当Al_2O_3的含量为20 wt%时,烧结的陶瓷颗粒致密均匀,陶瓷的抗弯强度最佳,浆料表观粘度增加;增加Al_2O_3的含量到40 wt%,陶瓷出现较多气孔,浆料的表观粘度增加幅度不大;Al_2O_3的添加影响了复相陶瓷的致密性、晶粒尺寸、相结构等因素;制备ZrO_2/Al_2O_3复相陶瓷时,最佳工艺参数为20 wt%Al_2O_3和80 wt%ZrO_2。     

增韧Z_rO_2陶瓷的研究

以Y_2O_3为固溶剂采用机械粉碎法制备的亚微米级ZrO_2粉末为原料,制造出高强度、高韧性的ZrO_2陶瓷。通过制定合理的配方以及控制烧成工艺条件,可以在坯体中获得大量的亚稳四方ZrO_2。当Y_2O_3加入量为2.5mol％时,抗折强度达978MPa,断裂韧性达15.1MPam~1/2。其增韧机理属于应力诱导相变增韧。     

低温烧结20wt% ZrB_2(ZrO_2)/Al_2O_3复相陶瓷及微观结构表征

在高纯亚微米Al_2O_3粉中添入质量分数为20 wt%的亚微米ZrB_2(ZrO_2)粉体,采用高压干压的成型方法和恒速升温多阶段小保温的烧结方法制备出ZrB_2(ZrO_2)/Al_2O_3复相陶瓷。采用XRD、EDS和SEM对ZrB_2(ZrO_2)粉体和复相陶瓷进行相组成、元素分布和微观结构表征。结果表明:1500℃/8 h烧结制备的20 wt%ZrB_2(ZrO_2)/Al_2O_3复相陶瓷微观结构优良;杂质元素诱导晶粒生长,导致复相陶瓷表面出现Al_2O_3和ZrB_2(ZrO_2)聚集相;引入的ZrB_2(ZrO_2)颗粒使复相陶瓷发生剧烈的穿晶断裂,ZrB_2(ZrO_2)晶粒带动周围的Al_2O_3晶粒发生明显的撕裂,断裂模式为穿晶-沿晶混合断裂。     

添加聚醚醚酮对Al_2O_3陶瓷组织及性能的影响（英文）

为改善氧化铝陶瓷的耐磨性和耐蚀性,用喷雾造粒的方法将PEEK(聚醚醚酮)加入到由亚微米氧化铝粉末制备的团聚粉中,制备了Al_2O_3陶瓷基复合涂层材料。用扫描电子显微镜分析了复合材料的组织结构,测试了复合陶瓷涂层的耐磨性和耐腐蚀性,并与纯氧化铝的性能进行对比。结果表明:添加PEEK的Al_2O_3复合陶瓷涂层在磨损试验中的摩擦系数低于Al_2O_3陶瓷,摩擦磨损更稳定,耐磨性更高,在20和30 N载荷下,复合涂层的平均摩擦因数分别为0.593 0和0.589 6,降低了15.8%和15.6%,平均磨损量分别降低了15.7%和17.6%;相对于Al_2O_3陶瓷涂层,复合陶瓷涂层的自腐蚀电位提高15.3%,电流密度降低47.5%,耐腐蚀性提高。     

添加聚醚醚酮对Al_2O_3陶瓷组织及性能的影响（英文）EI北大核心CSCD

为改善氧化铝陶瓷的耐磨性和耐蚀性,用喷雾造粒的方法将PEEK(聚醚醚酮)加入到由亚微米氧化铝粉末制备的团聚粉中,制备了Al_2O_3陶瓷基复合涂层材料。用扫描电子显微镜分析了复合材料的组织结构,测试了复合陶瓷涂层的耐磨性和耐腐蚀性,并与纯氧化铝的性能进行对比。结果表明:添加PEEK的Al_2O_3复合陶瓷涂层在磨损试验中的摩擦系数低于Al_2O_3陶瓷,摩擦磨损更稳定,耐磨性更高,在20和30 N载荷下,复合涂层的平均摩擦因数分别为0.593 0和0.589 6,降低了15.8%和15.6%,平均磨损量分别降低了15.7%和17.6%;相对于Al_2O_3陶瓷涂层,复合陶瓷涂层的自腐蚀电位提高15.3%,电流密度降低47.5%,耐腐蚀性提高。     

ZTA陶瓷ZrO_2的韧化机制与断裂特征

选用无压烧结和热压烧结两种系列不同成分配比的ＺｒＯ＿２韧化Ａｌ＿２Ｏ＿３（ＺＴＡ）陶瓷，在较宽的力学性能范围内研究７ｒＯ２的韧化机制对材料强度、韧性的贡献及其与断裂特征之间的关系。压痕裂纹揭示出ＺｒＯ＿２的不同韧化机制有不同的开裂特征：微裂纹韧化的材料，压痕裂纹弯曲行进，并且沿着ｍ－ＺｒＯ＿２颗粒与基体的交界面扩展；相变韧化的材料，压痕裂纹穿越ｔ－ＺｒＯ＿２颗粒。此特征能很好地解释：微裂纹韧化可以提高材料的断裂韧性，但有可能降低材料的断裂强度，相变韧化既可以提高材料的断裂韧性，又可以提高材料的断裂强度。     

ZrO2增韧Al2O3—TiC系陶瓷复合材料的力学性能及其耐磨性能

本文通过对ＺｒＯ２增韧Ａｌ２Ｏ３－ＴｉＣ系复相陶瓷材料的制备工艺以及ＺｒＯ２含量的变化对材料断裂韧性、抗弯强度以及硬度的影响研究，采用Ｘ射线衍射法分析断口相变量随组成变化对多元系相陶瓷断裂韧性、抗弯强度的影响，同时分析在不同冲击工况下其耐冲蚀磨损特性与力学性能之间的关系。     

Sliding Wear Behavior of ZTA with Different Yttria Stabilizer Content

In this study, tribological investigations were carried out on ZTA ceramics with 17 vol% Y‐TZP and different stabilizer contents (1, 1.5, and 2 mol% yttria) to analyze the influence of zirconia transformation on wear properties. Samples were tested in a linearly reciprocating ball on flat setup with different applied loads. Raising the fracture toughness by transformation toughening, microcracking, and residual stresses improves the wear resistance only at transition load but increases the wear at high loads. Higher yttria content of 2 mol% and lower zirconia grain size and thus low transformability, decreases fracture toughness but increases the wear resistance at high loads. Therefore the adjustment of stabilizer content on zirconia volume fraction in ZTA plays a decisive role in tribological applications.     

Al_2O_3–ZrO_2复相陶瓷的低温力学性能和热学性能

采用无压烧结法制备Al2O3–15%（质量分数）ZrO2（简称ZTA）复相陶瓷,研究了ZTA复相陶瓷在293～77K的力学性能以及300～5K的热学性能,分析了ZTA复相陶瓷在不同温度断裂时断面上ZrO2发生的相变量和相变区宽度。结果表明：ZTA复相陶瓷的抗弯强度、断裂韧性和Vickers硬度均随温度下降而逐渐提高;77K时抗弯强度、断裂韧性和Vickers硬度比293K时分别提高了10.8%、19.7%和10.4%;ZTA复相陶瓷的热导率随温度下降先增大,在97K时达到最大值,然后随温度下降而降低。低温环境增强了ZTA复相陶瓷中应力诱导t-ZrO2→m-ZrO2的相变增韧效应,提高了ZTA复相陶瓷的低温力学性能。ZTA复相陶瓷具有良好的低温力学性能和较小的低温热导率,是一种有广阔应用前景的低温结构陶瓷材料。     

Improved ageing-resistance and fracture toughness of zirconia-toughened alumina bioceramics via composition and microstructure design

Low-temperature degradation (LTD) is the main obstacle that hinders the application of zirconia-toughened alumina (ZTA) ceramics as artificial hip joints. In this study, a new type of ZTA bioceramic with LTD resistance, high fracture toughness, and superior wear resistance was prepared by the in-situ formation of plate-like crystals and co-stabilised tetragonal phase zirconia (t-ZrO₂). This new design is realised by synthesising nanocrystalline PrAlO₃ through a one-step solution combustion method and introducing it into a ZTA matrix to form praseodymium hexaaluminate (Pr_0.833Al_11.833O₁₉, PHA) plate-like crystals by solid-state sintering. PHA plays a key role in toughening and Y–Pr co-doped t-ZrO₂ slows down the low-temperature degradation of ZTA bioceramics. After hydrothermal ageing, the combination strategies have a positive influence on the flexural strength, fracture toughness, and Vickers hardness of the ceramics. This study provides a novel direction for ensuring long-term safety of bioceramics.     

Mechanical properties of zirconia toughened alumina with 10–24 vol.% 1.5 mol% Y-TZP reinforcement

Structural ceramics such as ZTA require high bending strength, fracture toughness and wear resistance. In order to achieve optimum mechanical properties, processing and compositional parameters have to be adjusted. ZTA ceramics with an yttria content of 1.5 mol% and zirconia contents ranging from 10 to 24 vol.% were hot-pressed at 1475 °C at 50 MPa axial pressure. Stabilization of the reinforcement phase in ZTA with yttrium oxide was performed by coating of monoclinic zirconia nanopowders via the nitrate route and subsequent blending with sub-micron size alumina. Three different dwell times of 1–3 h were applied to test the sensitivity to heat treatment conditions. Mechanical and microstructural properties were investigated. Bending strength strongly depends on zirconia content and reaches a maximum of 1288 MPa at 24 vol.%. In a second step a variation of yttria stabilizer content from 1 to 2 mol% in 24 vol.% ZTA was tested to achieve further improvements of mechanical properties.     

四方氧化锆多晶瓷的磨料磨损

四方氧化锆多晶瓷在实验条件下，由于磨损表层发生了由四方氧化锆转变为单斜氧化锆的马氏体相变，其磨料磨损率随施加载荷的增加反而减小，耐磨料磨损性能优于氧化锆增韧氧化铝瓷、普通氧化铝瓷。实验用陶瓷材料的表面磨损破坏主要为显微断裂脱落和由于晶粒部分破碎而形成的粉末刻划式磨痕。尽可能提高材料的断裂韧性并适当改善其硬度，将提高材料的磨料靡损性能。     

Wear properties of Y–α/β composite sialon ceramics

The tribological properties of yttrium containing α/β composite sialon ceramics have been studied under non-lubricated conditions by means of block-on-ring and ball-on-disk type experiments against a commercial silicon nitride material. The sialon ceramics were produced by hot pressing powder mixtures of Si₃N₄, AlN, Al₂O₃ and Y₂O₃, resulting in composite ceramics containing different amounts of the α/β phases. The effects of microstructural differences on the mechanical properties of the ceramics, and their wear characteristics under a range of testing conditions have been assessed. It was found that Vickers hardness decreased whilst both fracture toughness and bending strength increased with increasing amount of β phase in the composite. Under mild testing conditions, material removal was considered to occur by polishing of the surface, and in this case the high α-sialon composites exhibited the highest wear resistance, reflecting their higher hardness. Under severe testing conditions, the wear behaviour was characterised as microcracking caused by the higher Hertzian stress levels, and resulted in grain removal or “dropping” from the surface of the materials. Under these conditions, the elongated microstructure and higher fracture toughness of the low α-sialon composites hinder the crack propagation and result in better wear characteristics when compared to the fine equiaxed α-sialon materials.     

Toughening mechanisms of ZTA ceramics at cryogenic temperature (77 K)

ZTA ceramics containing 20 wt% ZrO₂ were fabricated at different sintering temperatures (1450, 1500 and 1550 °C) by SPS and HP processes, respectively. The influence of sintering process on the mechanical properties of ZTA ceramics at 298 K and 77 K was investigated. It can be seen that the bending strength and fracture toughness of samples prepared by the two processes both improved at cryogenic temperature. The stress-induced martensitic transformation toughening mechanism was confirmed by the in-situ Raman technique. The tetragonal ZrO₂ would be even more easy to transform because of the residual stress generated when temperature decreased from 298 K to 77 K. Therefore, the transformation toughening effect would become stronger, result in the increase of mechanical properties.     

莫来石陶瓷的摩擦磨损特性

采用环-块式摩擦副,研究了自相配莫来石陶瓷在不同的介质和载荷下的摩擦磨损特性.试验结果显示,莫来石陶瓷以水为介质时在20N、以机油为介质时在1000N附近存在磨损突变.磨损突变前主要的磨损机理为塑性变形和犁耕;磨损突变后断裂磨损成为主要的磨损机理.机油为介质时,磨损率与载荷基本成线性关系;在以水为介质时,磨损突变前,这种关系更接近于0.40次幂.弹性模量和抗弯强度高、断裂韧性和硬度低的样品,其磨损率高.通过扫描电子显微镜形貌观察,发现在水为介质时,磨损表面被一层反应膜所覆盖.