Al2O3-ZrO2(3Y)-SiC纳米复合材料的制备及性能

本文研究了非均相沉淀法制备Al2O3－ZrO2（3Y）－SiC复合粉体的工艺过程,认为粉体的理烧温度是至关重要的,热压烧结得到了致密的Al2O3－ZrO2（3Y）－SiC纳米复合材料,ZrO2的加入对烧结温度的影响不大．通过TEM观察,SiC颗粒均匀分散于材料中,大的ZrO2颗粒位于Al2O3晶粒间,小的圆形ZrO2颗粒位于Al2O3晶粒内,一部分Al2O3晶粒呈非等轴状．80Wt％Al2O3－15wt％ZrO2－5Wt％SiC纳米复合材料的抗弯强度可达555MPa,韧性为3.8MPa．m1／2.     

ZrO_2增韧Al_2O_3陶瓷的力学性能和增韧机制

对通过热压烧结法制备的3种陶瓷99.5vol%Al2O3(AD995)、ZrO2(15vol%)/Al2O3和ZrO2(25vol%)/Al2O3的力学性能和增韧机制进行了实验和理论研究。基于复合材料细观力学理论并考虑ZrO2的相变特性,建立了描述ZrO2/Al2O3陶瓷力学性能的本构模型。结果表明:ZrO2的加入细化了基体Al2O3晶粒,ZrO2/Al2O3陶瓷的致密性得到提高;3种陶瓷试件的破坏呈现小变形到脆性破坏的特点,压缩加载下试件应力-应变曲线近似为线性关系;AD995陶瓷的断裂韧性为5.65 MPa·m1/2,ZrO2(25vol%)/Al2O3陶瓷的断裂韧性为8.42 MPa·m1/2,提高了近50%;随ZrO2增韧相含量的增加,ZrO2/Al2O3陶瓷的弹性模量降低而断裂韧性增加,这一变化趋势与实验结果有良好的一致性。     

ZTA陶瓷托槽材料的研究

采用高纯Al2O3(99.7%)粉末和3mol%Y2O3稳定的ZrO2粉末,用机械混合法制备ZTA复合材料,将制得粉体进行热压铸成型,制备陶瓷正畸托槽.研究了不同含量的ZrO2(3 mol%Y2O3)、以及添加剂对ZTA陶瓷的显微结构和弯曲强度的影响.研究表明,添加适量的ZrO2能有效提高Al2O3陶瓷的抗弯强度,可以达到580MPa以上.加入的MgO形成了MgAl2O4相,抑止基体晶粒的长大,提高了致密度.     

复合陶瓷涂层对碳钢防腐蚀性能的电化学研究

利用电化学阻抗谱法就Al2O3、SiC、ZrO2复合陶瓷涂层对碳钢的防腐蚀性能进行了研究.结果表明:ZrO2复合陶瓷涂层的防腐蚀性能明显高于Al2O3、SiC复合陶瓷涂层.讨论了阻抗谱图特征变化与涂层结构与性能变化的关系.     

添加剂对离心自蔓延高温合成陶瓷层组织结构与性能的影响

为了改善钢管内衬陶瓷层的韧性,在铝热剂中分别添加ZrO2,Al2O3,SiO2进行改性,采用离心自蔓延高温合成工艺制备了钢管内衬陶瓷层,研究了添加剂对陶瓷层形貌、结构和性能的影响.结果表明:加入ZrO2或Al2O3可以改变陶瓷层的组织结构,使Al2O3由树枝状晶变为等轴晶;加入SiO2可在Al2O3枝晶间隙形成网状Ca...     

Al2O3/ZrO2/ZrSiO4复合材料的研究

在Al2O3颗粒补强锆英石陶瓷的研究基础上,探讨了Al2O3与ZrO2共同对锆英石陶瓷的协同补强增韧行为.制备的锆英石基复合材料的室温抗弯强度和断裂韧性分别可达383.31MPa、4.39 MPa·m12.采用XRD分析了复合材料的相组成,采用SEM观察复合材料的断面形貌.结果显示:ZrSiO4为主要晶相,另外还有少量Al2O3和ZrO2存在;第二种增强体ZrO2的最佳引入量为20％(质量分数);确定复合材料的强韧化是由Al2O3和ZrO2颗粒引起的裂纹偏转、微裂纹增韧与ZrO2颗粒引起的相变增韧共同作用而实现的,断裂方式主要为穿晶断裂.     

晶粒细化对Al2O3／ZrB2／ZrO2复合陶瓷材料力学性能的影响

采用普通球磨细化工艺和两次球磨细化工艺制备出两类Al2O3/ZrB2/ZrO2复合陶瓷材料,并对材料的硬度、断裂韧性和抗弯强度进行了测试和分析.结果表明,两次球磨细化工艺可以明显降低ZrB2/ZrO2晶粒的尺寸至0.2～0.4μm,使其在Al2O3基体内的分布更均匀,并能有抑制Al2O3晶粒的异常长大.与普通细化工艺相比较,此工艺改变了材料的断裂模式,强化了晶界的结合能力,使复合材料的综合力学性能得到了更大程度的改善,其中抗弯强度和硬度最多提高了48%和41%.     

脉冲电沉积RE-Ni-W-B-PTFE-Al2 O3复合镀层性能的研究

高性能复合镀层具有优良的耐磨、耐蚀性能,能满足工业生产对材料性能的要求.研究了脉冲电沉积RE-Ni-W-B-PTFE-Al2O3复合镀层的成分、形貌及性能.结果表明:脉冲电流及Al2O3固体颗粒能明显提高RE-Ni-W-B-PTFE-Al2O3复合镀层中W和B的含量;与直流电沉积相比,脉冲电沉积RE-Ni-W-B复合镀层的表面裂纹已明显减小,但裂纹仍存在,当Al2O3耐磨颗粒及PTFE减摩微粒嵌入RE-Ni-W-B复合镀层中以后,在SEM 400倍下观察,RE-Ni-W-B-PTFE-Al2O3镀层已不存在裂纹, 而且镀液中Al2O3颗粒含量越多,晶粒就越细;此外,研究表明,镀液中Al2O3颗粒含量增加, RE-Ni-W-B-PTFE-Al2O3复合镀层镀态硬度增加,磨损率降低.     

纳米SiC颗粒对Al2O3基体中ZrO2约束稳定的影响

采用热压的方法制备了纳米SiC颗粒复合的Al2O3-ZrO2陶瓷材料，研究了纳米SiC颗粒对样品烧结性能以及对Al2O3基体中ZrO2约束稳定的影响。结果表明，纳米SiC颗粒的加入影响样品的烧结性能。处于晶界的纳米SiC颗粒降低了基体材料对ZrO2颗粒的约束，不利于四方相ZrO2在室温下的保留。     

微波法制备ZrO2/Al2O3复合载体及其性能的研究

采用真空浸溃和微波技术在经过扩孔处理的Al2O3载体上制备ZrO2/Al2O3复合载体.经XRD、DSC-TG、TPD等测试表明:ZrO2能单层分散在Al2O3表面,分散阈值为0.242gZrO2/gAl2O3;在微波条件下,ZrO2的单层分散没有明显改变Al2O3的孔径分布,复合载体具有较好的热稳定性,ZrO2单层分散的复合载体表面具有酸、碱性质,碱性中心数大于非单层分散的复合载体,同时单层分散的复合载体具有较大的比表面积和适宜的孔径分布.初步证明,Al2O3能诱导单层分散ZrO2产生新的碱性中心.     

Surface morphology,tribological properties and in vitro biocompatibility of nanostructured zirconia thin films

Deposition of nanostructured and low-wear zirconia (ZrO₂) thin films on the metallic component of a total joint implant is envisaged to reduce wear of the soft ultra-high molecular weight polyethylene (UHMWPE) counterpart. In this work, morphological surface features, wear resistance and in vitro-biocompatibility of zirconia thin films deposited by the novel Pulsed Plasma Deposition (PPD) method have been investigated. Film thickness, roughness and wettability were found to be strongly dependent on deposition gas pressure. Interestingly, wear rate of UHMWPE disks coupled to zirconia-coated titanium spheres was only poorly correlated to the contact angle values, while film roughness and thickness seemed not to affect it. Furthermore, wear of UHMWPE, when coupled with zirconia coated-titanium spheres, significantly decreased with respect to uncoated spheres under dry or NaCl-lubricated conditions; besides, when using bovine serum, similar results were obtained for coated and uncoated spheres. Finally, suitable mesenchymal stem and osteoblast cells adhesion, proliferation and viability were observed, suggesting good biocompatibility of the nanostructured zirconia films. Taken together, the results shown in this work indicate that zirconia thin films deposited by the PPD method deserve further investigations as low-wear materials for biomedical applications such as total joint replacement.     

Status of surface modification techniques for artificial hip implants

Surface modification techniques have been developed significantly in the last couple of decades for enhanced tribological performance of artificial hip implants. Surface modification techniques improve biological, chemical and mechanical properties of implant surfaces. Some of the most effective techniques, namely surface texturing, surface coating, and surface grafting, are applied to reduce the friction and wear of artificial implants. This article reviews the status of the developments of surface modification techniques and their effects on commonly used artificial joint implants. This study focused only on artificial hip joint prostheses research of the last 10 years. A total of 27 articles were critically reviewed and categorized according to surface modification technique. The literature reveals that modified surfaces exhibit reduced friction and enhanced wear resistance of the contact surfaces. However, the wear rates are still noticeable in case of surface texturing and surface coating. The associated vortex flow aids to release entrapped wear debris and thus increase the wear particles generation in case of textured surfaces. The earlier delamination of coating materials due to poor adhesion and graphitization transformation has limited the use of coating techniques. Moreover, the produced wear debris has adverse effects on biological fluid. Conversely, the surface grafting technique provides phospholipid like layer that exhibited lower friction and almost zero wear rates even after a longer period of friction and wear test. The findings suggest that further investigations are required to identify the role of surface grafting on film formation and heat resistance ability under physiological hip joint conditions for improved performance and longevity of hip implants.     

Wear behaviour of a novel aluminium–nanozirconia composite

A novel aluminium–zirconia composite, with improved wear resistance, has been produced. The method consists of compacting aluminium powder mixed with cellulose fibres, which are then eliminated by a heat treatment. The compacted piece was immersed several times in a colloidal (i.e. nanosized) zirconia solution until a constant weight was reached. The solution penetrated and infiltrated the preform. Then, the aluminium matrix presented zirconia tetragonal and monoclinic phases. Wear test was carried out in a pin-on-disc machine. By measuring the weight loss it was shown that the composite had significant improvement in wear resistance, as compared to pure aluminium.     

高性能陶瓷人工髋关节材料摩擦磨损研究发展

陶瓷已经在人工髋关节假体制作中获得一定的应用,并且有更大的潜力以待开发.对于陶瓷人工髋关节假体,其摩擦磨损性能是决定其寿命的最重要的性能之一,而体外的摩擦磨损测试对于确定其摩擦磨损性能有着重要意义.本文综述了国内外对于氧化铝、氧化锆、氮化硅和碳化硅四种陶瓷的摩擦磨损性能的研究结果,并且结合作者的工作对其进行评论.     

Improving Bearing Surfaces of Artificial Joints

The requirements for materials to be used for bearing surfaces in joint replacement are corrosion resistance in the body environment, reliability, hardness, and stiffness. Most important is coverage of the bearing surface with a stable oxide layer, so that the articulating surfaces can be lubricated by the synovial fluid. The synovial fluid, being a protein, can degenerate during frictional heating. This can be avoided if the materials used for wear couples have very good thermal conductivity. Bioceramics for joint replacement have been used since the 1970s. Alumina ceramics reduce the wear rate and solve the problem of implant loosening (osteolysis). Although the in vivo fracture rate for alumina parts is very small, further improved reliability is demanded. Alternative materials may be non‐oxide ceramics, zirconia ceramics, or hard coatings on metals. Advanced non‐oxide ceramics, such as SiC and Si₃N₄, are not suitable for bearing surfaces in knee‐ and hip‐joint replacement because the surface oxide formed is SiO₂, which chips off. Y‐TZP zirconia does not have adequate phase stability. All hard coatings tried hitherto (TiN, DLC) have not been good enough. Alumina matrix composite (AMC) is a new type of bioceramics. AMC offers excellent tribological properties, no frictional heating, improved mechanical strength and fracture toughness, thus more in vivo reliability. So far test results have been very promising.     

齿科用氧化锆陶瓷韧性研究进展

氧化锆陶瓷具有高强度、高韧性、高硬度、耐磨损、生物相容性好等优点, 广泛应用于齿科修复。但氧化锆陶瓷相变增韧会缩短其服役寿命, 尤其在极潮湿的口腔唾液等复杂的生物化学条件下, 因承受咀嚼力、温度的频繁变化, 而导致其失效断裂。本文概述了氧化锆陶瓷在齿科修复领域的应用研究进展, 总结了氧化锆陶瓷的增韧机理以及常用齿科氧化锆陶瓷的研究现状, 并对临床服役中氧化锆陶瓷的韧性老化现象进行分析, 总结了韧性老化机理及其预防措施和方法。随着齿科氧化锆陶瓷综合力学性能的提高以及健康功能化的未来需求, 其在生物医用领域的应用将会越来越广泛。     

Friction and wear properties of UHMWPE composites reinforced with carbon fiber

The artificial joint acetabular material ultrahigh molecular weight polyethylene (UHMWPE) was reinforced with carbon fibers (CF) in different contents. The effects of CF content on hardness and tribological properties of the materials were studied. The morphologies of wear surfaces were examined with a Scanning Electron Microscope (SEM). The results show that the hardness and wear resistance of CF-reinforced UHMWPE composites increased with CF content; the friction coefficients under distilled water lubrication were decreased greatly by the addition of CF; that adherence, plowing, plastic deformation and fatigue wear are dominant for the UHMWPE under dry sliding, and that abrasive wear and drawing out of CF from the wear surface of the composites are dominant for the CF-UHMWPE composites under both dry and distilled water lubrication conditions.     

Tribological Performance of Bioimplants: A Comprehensive Review

Total joint replacements(TJR) have been a huge success for orthopaedic surgery in the past century and are gaining increasing importance today due to the aging population. However, the short longevity of artificial joints is one of the major problems in bioimplant industry and needs to be rectified since an increasing number of young people, with more active lifestyles, must receive TJR. Wear mechanisms are discussed in this paper to describe the root causes of the failures and to give some general ideas to increase the lifespan of artificial joints. The suitable material combination is of great importance for the wear resistance of bioimplants, and bioceramics will exert a crucial effect in their future progress. Other materials, such as metal alloys and polymers, are also discussed in this paper. Surface finish is another factor affecting the tribological performance of bioimplants. In recent years, surface texture technology has fascinated many researchers, and a good design of texture pattern requires a comprehensive understanding of wear mechanisms, material properties, and dynamic fluid theory. This review also covers a summary of in vitro wear tests, including simulators, lubricant, and testing parameters.     

Thermal shock resistance of ZrO2 based ceramics

Thermal stress fracture behaviour of zirconia based ceramics are described. Although partially stabilized zirconia (PSZ) and tetragonial zirconia polycrystals (TZP) ceramics show superior mechanical properties such as high fracture strength/fracture toughness, the thermal shock resistance of zirconia ceramics is anomalously low. The thermal stress fracture mechanism and improvement of the thermal shock resistance are discussed.     

Wear Characteristics of Zirconia Toughened Ceramic Drawing Dies

Wear resistance of several zirconia toughened ceramics in comparison with a metal-ceramic CoWC has been studied in drawing wire field test. Result indicates that the harder the ceramic die, the longer the service life. Excellent wear resistance of ceramic die is obtained with a very high hardness (19 GPa). The service life is nearly three times that of Co-WC die. SEM observation on wear surfaces showed that material removal is mainly caused by plastic flow and ploughing process. But when the ceramic is composed of zirconia, alumina and some titanium carbide, micro-chipping and tribochemical reaction take place, and wear rate increases. Wear and friction induced martensite was detected by XRD. The T-M (tetragonal to monoclinic) phase transformation has a contribution to inhibiting microfracture.