氧化铝/氮化铝陶瓷显微组织研究

氮化铝具有良好的热学、电学和机械等性能,是理想的电子封装材料和高性能陶瓷基板材料.本文研究了AlN加入量和烧结温度对Al2O3/AlN复相陶瓷相组成和显微组织的影响.结果表明该陶瓷在1400～ 1550℃烧结时,AlN被部分保留,少量氧原子进入AlN晶格,烧结生成4种铅锌矿结构新相,有利于提高复相陶瓷热导率;氮化铝含量和烧结温度的提高,有利于形成大尺寸晶粒.     

添加稀土氧化物对氧化铝复相陶瓷性能的影响

采用复合烧结助剂降低氧化铝复合陶瓷（zironia-toughened aluminum,ZTA)烧结温度并保持优良力学性能，着重就不同稀土氧化物对材料烧结性，力学性能和显著结构的影响进行了研究，复合添加剂促进了ZTA陶瓷的烧结，但不同添加剂对材料力学性能产生了不同影响，含Y2O3添加剂因生成富钇晶界相而使材料的强度受到损害，而含La2O3和／或CeO2添加剂使材料力学性能获得提高，在1400－1450℃烧结强度超过500MPa，断裂韧性达6．5MPa.m^1/2以上，该ZTA陶瓷断裂路径曲折，裂纹出现架桥，分叉等现象，使断裂能提高。     

Cr2O3添加对ZTA复相陶瓷显微结构和力学性能的影响

采用无压烧结制备ZTA复相陶瓷,探究Cr2O3的添加对ZTA复相陶瓷显微组织和力学性能的影响.结果表明:Cr2O3会促进Al2O3晶粒的生长,并出现长条状Al2O3晶粒;随着Cr2O3的增加,复相陶瓷的密度、硬度、断裂韧性均呈现先增大后减小趋势.在Cr2O3添加量为0.6％时具有最佳性能,但过多的Cr2O3会使陶瓷内部...     

常压烧结莫来石／氧化锆／碳化硅复相陶瓷的研究

本文对莫来石／氧化锆／碳化硅复相陶瓷进行了Ｎ２气氛中常压烧结的研究。实验结果表明：ＳｉＣ粒子添加量≤２０ｖｏｌ％，材料均可致密烧结并可获得均匀的微观结构。ＳｉＣ粒子的加入使材料人力学性能较莫来石／氧化锆陶瓷有明显的提高，并在ＳｉＣ含量为１０ｖｏｌ％时达到峰值，室温强度和断裂韧性分别为６０１ＭＰａ和５．８ＭＰａ＾Ｃ２，接近热压材料。     

晶内型结构的Al2O3/SiCp纳米复相陶瓷

利用非均匀成核的方法在纳米SiC粒子表面包覆一层Al2O3,通过胶态悬浮液将其均匀分散于Al2O3基体中,制备出晶内型结构为主的Al2O3/SiCp纳米复相陶瓷。通过对材料显微结构及断口形貌分析,发现Al2O3/SiCp纳米复相陶瓷中,含纳米SiC粒子的Al2O3晶粒内,在残余热应力作用下产生了大量的位错,位错的交截,组合导致微裂纹成核,从而诱发材料发生非平面穿晶断裂,说明晶内SiC粒子是改变材料断裂模式的主要原因。     

氧化锆基纳米复相陶瓷磨介剪裁设计

机械研磨是当前制备超细粉体最广泛使用的方法，但目前市场上难以找到与之配套使用的价格不太高、耐磨性等综合性能好的磨介。本文在深入理解TZP材料耐磨机理及其配方工艺技术的基础上，进行正确设计、裁剪、组合，设计生产了质优价廉、适用性强的氧化锆基纳米复相陶瓷磨介，它低廉的价格和超值的质量将为非金属矿超细加工行业的规模化发展，提供一个重要的基础。     

ZrSiO4/Al2O3烧结氧化铝-莫来石复相陶瓷微观结构的研究

将氧化铝和锆英石混合物试样分别在1350℃、1550℃下烧成，结果发现在1350℃烧成、保温3h的样品中有莫来石生成，而在1550℃烧成、保温3h的情况下却未发现莫来石生成，本文对此作了分析和探讨。关键词：氧化铝一莫来石，复相陶瓷，微观结构。     

氧化锆基纳米复相陶瓷研磨介质的研制与应用

用Y-TZP作为基础相,采用成功的粉体制作工艺,复合AlCl3·6H2O进行化学法混合,然后加入自制的纳米莫来石A3S2和纳米SiO2进行混磨,制备了纳米氧化锆复相陶瓷ZTC。利用Y-TZP材料优良的室温力学性能,同时加入适量的添加剂SiO2和Al2O3,促进莫来石材料的形成,提高其在较高温度下抗水解、抗老化、硬度高的性能。所制得的ZTC材料,既保留了TZP材料优良的室温耐磨性,同时又避免了在水热蒸汽下温度高于60℃时TZP材料较易水解老化的问题,与TZP、Al2O3磨介相比,其性能价格比最优,铝球的价格低、锆球的质量好,使材料的应用领域得到扩展。     

冲击加载下氧化铝/碳化硅复相陶瓷局部变形特征分析

为深入研究复相陶瓷在冲击加载下的宏观力学响应特性与微观断裂机制,选取Al₂O₃/SiC复相陶瓷为研究对象,设计了一维应力波和平面冲击波加载测试方法,研究了材料动态强度及其应变率效应、高压Hugoniot曲线以及不同受力特征下的材料局部变形机制。结果表明：不同的宏观受力特征下复相陶瓷对应有不同的微观断裂机理;冲击加载下材料的宏观变形主要是脆性破坏,但从微观角度观察,大尺寸晶粒穿晶断裂以及小尺寸晶粒沿晶断裂存在明显的局部塑性变形特征;第二相SiC颗粒在晶界和晶粒内部诱导裂纹传播,起到了冲击能量再分配的作用。     

原位合成TiB2-TiCx复相陶瓷的显微组织

应用光学显微镜(OM)、X射线衍射(XRD)、透射电镜(TEM)和扫描电镜(SEM)对原位合成的TiB2-TiCx复相陶瓷显微结构进行了分析。并分析了Ti-B4C反应的原位生成机理。结果表明,Ti3B4相稳定存在于生成物中,其形态与形成温度和反应机理有关。     

High-density nanoprecipitation mechanism and microstructure evolution of high-performance Al2O3/ZrO2 nanocomposite ceramics

Al₂O₃/ZrO₂ supersaturated solid solution micro-powders (AZ-SSP) with three components were successfully obtained by combustion synthesis assisted rapid water cooling, and their nanoprecipitation mechanism and microstructure evolution were studied by phase field simulation and hot-press sintering. The results show that AZ-SSP could be used to fabricate Al₂O₃/ZrO₂ nanocomposite ceramics (AZNC) with intragranular-intercrystalline microstructures by high-density nanoprecipitation, consistent with microstructures of heat-treated AZ-SSP via the phase field simulation. There were three simulated nanostructures of spherical and elongated particles in A57Z-SSP or A15Z-SSP and interlocking structures in A36Z-SSP. The submicro-crystals of A57ZNC and A15ZNC contain high-density nano- and supra-nano-particles, and the fracture toughness of these two ceramics can reach up to 10.37 ± 0.37 MPa·m^1/2 and 12.63 ± 0.36 MPa·m^1/2, respectively. Hence, the preparation method of ultra-fine structures by supersaturated solid solution has far-reaching guiding significance for various nanoceramics.     

Phase transformation induced fatigue of a Ce-TZP/Al2O3 composite

In this study, the stress–cycle number (S–N curve) of a composite consisting of ceria-stabilized zirconia (Ce-TZP) and alumina (Al₂O₃) was measured. First, the initial bending strength of the Ce-TZP/Al₂O₃ composite was determined using a four-point bending technique. Next, stress above 70% of the initial bending strength was applied on the composite for up to 1,000,000 cycles. Transformation bands were formed on the tensile surface in the first several cycles as the stress was higher than a critical value. The number and width of bands then changed marginally after their fomraiton. Fatigue failure occured at the band with the largest width, as a result of slow crack growth process. The transformation bands could be removed using a post-fatigue heating treatment. After removal of these bands, the strength was consequently enhanced.     

Fabrication and Mechanical Property of BaNb2O6/Al2O3 Composite Ceramics

为研究功能材料对结构陶瓷微观结构和力学性能的影响,将铁电相 BaNb2O6引入到 Al2O3陶瓷中,分别采用无压和热压烧结技术于 1350 ℃制备 BaNb2O6/Al2O3复相陶瓷,对其物相组成、微观结构和力学性能进行了研究。结果表明：BaNb2O6与 Al2O3经过高温烧结能够稳定共存,BaNb2O6的加入促进了 Al2O3陶瓷的烧结。BaNb2O6加入量为 10%（体积分数）时,1350 ℃无压烧结和热压烧结制备的 BaNb2O6/Al2O3复相陶瓷的致密度、抗弯强度和断裂韧性分别为 94.6%、214MPa、2.28 MPa m1/2和 99.3%、332 MPa、3.55MPa m1/2。当裂纹扩展遇到 BaNb2O6晶粒时发生穿晶断裂,但在晶粒内部出现裂纹偏转,说明铁电相 BaNb2O6晶粒内部的微观结构有助于陶瓷的强韧化。     

Effect of CeO2 and Al2O3 contents on Ce‐ZrO2/Al2O3 composites

Effect of CeO₂ and Al₂O₃ contents on phase composition, microstructures, and mechanical properties of Ce–ZrO₂/Al₂O₃ composites was studied. The CeO₂ content in CeO₂–ZrO₂ varied from 7 to 16 mol%, and the Al₂O₃ content in Ce‐ZrO₂/Al₂O₃ composites were 7 and 22 wt%. When CeO₂ content was ≤10 mol%, high Al₂O₃ content contributed to hinder the tetragonal‐to‐monoclinic ZrO₂ phase transformation during cooling and decrease the density of microcracks in the composites. Tetragonal ZrO₂ single‐phase was obtained in the composites with ≥12 mol% CeO₂, regardless of the Al₂O₃ content. Hardness, flexural strength, and toughness were dependent on CeO₂ and Al₂O₃ contents which were related to the microcracks, grain size, and phase transformation. The high flexural strength and toughness of the composites with 7wt% Al₂O₃ could be obtained at an optimum CeO₂ content of 12 mol%, whereas those of the composites with 22 wt% Al₂O₃ could be achieved in the wide CeO₂ content range of 8.5‐12 mol%.     

Microstructure and electrical properties of 3Y-TZP/Al2O3 composite obtained using the citrate gel method

3Y-TZP sinters with 1, 5, 10, and 15 mol% of Al₂O₃ were prepared using two different procedures from a 3-YSZ powder synthesized via the citrate process. In the first procedure, alumina was introduced during synthesis via the citrate method. In the second one, the 3-YSZ powder was impregnated with aluminum nitrate. All samples were sintered at 1773 K. The prepared composites were evaluated in terms of their microstructure, chemical and phase composition, and electrical properties. The total conductivity of the 3Y-TZP/Al₂O₃ composite material, which contained primarily the tetragonal phase, was found to increase with temperature, and to decrease for reduced concentrations of alumina in 3Y-TZP. In the case of the samples which had alumina introduced via impregnation, its higher content was not associated with significantly lower electrical conductivity. These samples generally exhibited higher conductivity than the samples to which alumina had been added via chemical synthesis.     

Al2O3-SiC复相陶瓷材料制备方法的研究现状

简要论述了Al2O3-SiC复相陶瓷材料的常用制备方法,如无压烧结法、热压烧结法、气压烧结法和溶胶-凝胶法等,重点介绍了碳热还原法。对以不同原料制备Al2O3-SiC复相陶瓷材料的碳热还原法进行了比较,指出了这方面研究的不足之处和下一步研究的方向。     

添加ZrSiO4制备Al2O3/ZrO2/莫来石复相陶瓷的组织及力学性能研究

将一定质量的硅酸锆和氧化钇加入无水乙醇湿法研磨、干燥后,加入Al2 O3陶瓷粉料中,1550℃常压烧结,保温3h,制得陶瓷.研究所制备陶瓷的微观组织及其力学性能.结果表明:添加ZrSiQ之后,陶瓷中生成了t-ZrO2,ZrO2相变时的体积效应弥补了部分气孔,使复相陶瓷气孔减少,致密度提高;界面生成的ZrO2改变了材料的断裂方式,使材料的抗弯强度、断裂韧性、抗热震性能都得到明显的改善.     

Al2O3/SiC复合陶瓷的反应烧结

在空气中于1600℃对Al2O3/0.78%SiC纳米复合体进行2h的反应烧结,制得Al2O3/5%莫来石复合陶瓷,其中的莫来石分为两类,即3Al2O3·2SiC和Al5.65Si0.35O9.175。采用SEM和TEM研究Al2O3/莫来石复全陶瓷的微观结构。对Al2O3/莫来石复合陶瓷的密度和力学性能如杨氏模量、泊松比、硬度、韧性和强度进行了研究。     

Al2TiO5／ZrO2纳米复相陶瓷的制备及性能研究

以氧氯化锆((ZrOCl2·8H2O)、硫酸铝(Al2(SO4)3·18H2O)、硫酸氧钛(TiOSO4·2H2O)为初始原料,以氨水为沉淀剂,将液相共沉淀法得到的Al2TiO5/ZrO2纳米复合粉体前驱体,经1000℃焙烧2h,制备了ZrO2含量(w)为2%、5%、8%的Al2TiO5/ZrO2纳米复合粉体;复合粉体经造粒后以100Mpa压力成型试样,试样尺寸为53mm×10mm×10mm,经1350、1400、1450、1500℃2h制备了Al2TiO5/ZrO2(缩写AT/Z)纳米复相陶瓷试样。研究了ZrO2含量、烧结温度对试样的烧结性能、热膨胀性能、抗热震性能的影响,并借助XRD、SEM分析了试样的物相组成、显微结构。结果表明:随着ZrO2含量的增加和烧结温度的提高,试样的显气孔率减小,抗弯强度增大。烧结温度为1500℃、ZrO2含量(w)为5%的ATZ-54试样,抗弯强度最大,为103.2MPa;在1250℃的热膨胀率仅为0.08%,其热膨胀系数α约为0.65×10-6℃-1;AT/Z纳米复相陶瓷试样具有细晶镶嵌结构;从室温到1100℃急冷急热冲击31次后,试样表面仍保持完整,抗热震性能明显高于其他...     

Al2O3-ZrO2系共晶组成研究

配制了Al2O3-ZrO2系含ZrO2的质量分数分别为25%,30%,35%,40%,45%和48%的6个组成的试样于电炉中熔融并快速冷却.借助SEM-EDAX研究了试样的显微结构,结果表明:在含ZrO2的质量分数为25%～40%的试样中可观察到初晶刚玉和细卵状共晶相组成;在含ZrO2的质量分数为45%～48%的试样中可观察到初晶ZrO2相和细卵状共晶显微结构.借助于EDAX测定了含ZrO2的质量分数为40%和45%两试样的共晶组成,其结果为含ZrO2的质量分数为43.3±0.4%.