氧化物陶瓷增韧技术的研究

本文以工业纯ＺｒＯ２和工业纯Ａｌ２Ｏ３的原料,采用多元稳定剂的复合添加技术和弥散颗粒预合成工艺制备ＺＴＡ（氧化锆增韧氧化铝）复相陶瓷。通过对材料的制备、烧结性能和力学性能的研究,找出了与ＺＴＡ材料最佳抗弯强度和断裂韧性相对应的最佳工艺参数,并讨论了稳定剂含量以及弥散颗粒含量对ＺＴＡ材料力学性能的影响。     

无机盐先驱体溶胶—凝胶法制备50%Al2O3—50%ZrO2结晶复相陶瓷

采用无机盐先驱体，溶胶－凝胶法制备出超细５０％Ａｌ２Ｏ３－５０％ＺｒＯ２复合粉体，ＢＥＴ法测得其比表面积达２２７．４ｍ＾２／ｇ。复合粉体经热压烧结得到具有互渗结构的结晶复相陶瓷，其Ａｌ２Ｏ３晶粒约１００ｍｍ，ＺｒＯ２晶粒约０．６μｍ。     

无机盐先驱体溶胶凝胶法制备50%Al_2O_3-50%ZrO_2细晶复相陶瓷

采用无机盐先驱体，溶胶凝胶法制备出超细５０％Ａｌ２Ｏ３５０％ＺｒＯ２（以体积计）复合粉体，ＢＥＴ法测得其比表面积达２２７．４ｍ２／ｇ。复合粉体经热压烧结得到具有互渗结构的细晶复相陶瓷，其Ａｌ２Ｏ３晶粒约１００ｍｍ，ＺｒＯ２晶粒约０．６μｍ。     

添加Al2O2对ZrO2（Y2O3）粉末性能的影响

采用化学共沉淀法制备了ＺｒＯ２（Ｙ２Ｏ３）和ＺｒＯ２（Ｙ２Ｏ３）／Ａｌ２Ｏ３超细粉末，研究了添加Ａｌ２Ｏ３对粉末性能的影响。添加Ａｌ２Ｏ３提高了ｔ－ＺｒＯ２的结晶化温度，抑制了ＺｒＯ２－ｍ－ＺｒＯ２相变。Ａｌ２Ｏ３相变。Ａｌ２Ｏ３添加量超过２０ｗｔ％时，粉末烧结活性降低，烧结温度提高。     

热压Al2O3—ZrO2（6mol%Y2O3）陶瓷复合材料的组织性能研究

本文考察了全稳定ＺｒＯ２对Ａｌ２Ｏ３陶瓷的组织性能的影响。结果表明，热压Ａｌ２Ｏ３－ＺｒＯ２（６ｍｏｌ％Ｙ２Ｏ３）陶瓷材料的显微形貌与其它Ａｌ２Ｏ３－ＺｒＯ２陶瓷的几乎完全一样，小量ｃ－ＺｒＯ２的存在可促进Ａｌ２Ｏ３陶瓷的烧结并细化晶粒，从而提高材料的力学性能，但其增韧增强能力有限。大量ｃ－ＺｒＯ２的存在因其本身低的力学性能、缺乏相变韧化和存在残余拉应力而使材料的力学性能下降。     

ZrO_2_-3Al_2O_3-2Sio_2/SiC_n纳-微米复相陶瓷的反应烧结技术

概述复相陶瓷和纳米陶瓷的主要内容和机理,介绍反应烧结ＺｒＯ２－３Ａｌ２Ｏ３·２ＳｉＯ２－Ａｌ２Ｏ３／ＳｉＣｎ纳米复相陶瓷技术的研究内容、技术路线、工艺原理和发展前景。     

ZTA复相陶瓷凝胶注模成形工艺的研究

本文研究了ＺｒＯ２（３Ｙ）－Ａｌ２Ｏ３复相陶瓷的凝胶注模成形工艺,着重研究了低粘度高固相体积分数浓悬浮体的制备。     

Al2O3添加量对Y—TZP陶瓷烧结及力学性能的影响

研究了Ａｌ２Ｏ３添加量对Ｙ－ＴＺＰ陶瓷烧结及力学性能的影响，结果表明，微量Ａｌ２Ｏ３可固溶于ＺｒＯ２中而提高材料致密度，使Ｙ－ＴＺＰ的强度、耐磨性等力学性能也同时得到提高，过量Ａｌ２Ｏ３处ＺｒＯ２晶界上阻碍致密化，２０ｗｔ％Ａｌ２Ｏ３，１５５０℃，４ｈ未能烧结，使各项力学性能明显下降。     

纳米级ZrO2（Y2O3）／Al2O3粉末的制备及其烧结性能

本文采用化学共沉淀凝胶法制备了２ｍｏｌ％Ｙ２Ｏ３－ＺｒＯ２－２０ｗｔ％Ａｌ２Ｏ３纳米级超细复合的陶瓷粉末，在常压下对该粉末进行了不同温度下的烧结试验，利用ＸＲＤ分析了粉末的相组成；用ＸＲＤ－ＢＬ法计算了粉晶尺寸，用ＴＥＭ研究了粉末的形貌，大小及其分布，用Ａｒｃｈｉｍｅｄｅｓ法测定了烧结体的体积密度，用ＳＥＭ观察测定了烧结体的显微结构，结果表明，该法制备的粉末尺寸分布范围窄，分散性好，粉体烧结活性高     

湿化学法制备微晶（Y,Mg）—PSZ／MgAl2O4陶瓷的研究

研究了用湿化学法制备Ｙ２Ｏ３－ＭｇＯ－ＺｒＯ２－Ａｌ２Ｏ３四元系超细粉的工艺技术，探讨了包裹沉和包裹沉淀－乙酸镁混合两种制备工艺组成对微晶ＰＳＺ材料结构、性能的影响。经１１００℃适当时间的热处理获得了在ｃ－ＺｒＯ２中具有ｔ－ＺｒＯ２梭形析出体的微晶ＰＳＺ复相陶瓷，其室温强度达８００ＭＰａ，断裂韧笥在１４ＭＰａ，Ｍ＾１／２左右，１０００℃下高温强度可达４５８ＭＰａ。     

Influence of feedstock preparation on ceramic injection molding and microstructural features of zirconia toughened alumina

Feedstocks for ceramic injection molding of ZTA containing 90 vol.% of sub-μm alumina and 10 vol.% of zirconia nanopowder were prepared by different processing techniques. Feedstocks were prepared by mixing in a sigma-blade kneader and subsequent homogenizing by twin-screw extrusion or shear roll compaction. Two other feedstocks were previously bead milled and subsequently processed by the same procedure. Compounding technology strongly influences the injection molding behavior and microstructures of the final product. Despite higher energy input of the shear roll compactor, powder agglomerates cannot be completely avoided. Pre-milling is effective to disperse and deagglomerate ceramic powders. Injection pressures of feedstocks from pre-milled powders were about 200 bar lower compared to pressures needed for non-milled feedstocks. Present feedstock preparation methods are feasible to produce homogeneous feedstocks, which strongly influence microstructures. In order to produce high solid loaded sub-μm/nm feedstocks, processing methods, pre-treatment and solid content have to be carefully chosen.     

Aging effects on the characteristics and sintering behavior of coprecipitated Al2O3---ZrO2 powders

Effect of gel aging on the characteristics of zirconia-toughened alumina (ZTA) composites were investigated. The composite powders were prepared by coprecipitation processes using a mixed solution of aluminum nitrate and zirconium oxynitrate. The coprecipitates were aged in an aqueous solution of pH 9 at room temperature. The occurrence of either intra- or intergranular ZrO₂ particles in the Al₂O₃ matrix depended on the aging condition, which also affected the content of tetragonal ZrO₂ (t-ZrO₂). Aging treatment decreased the amount of intragranular ZrO₂, as well as the agglomerate strength of calcined powders, both of which seemed to improve the sintered densities of ZTA ceramic bodies. Through suitable aging processes, sintered ZTA specimens with relative density >99% and intergranular ZrO₂ particles were fabricated.     

Advancing spray granulation by ultrasound atomization

The influence of the atomization technique on the suitability of granules for dry pressing is the focus of the presented investigations. Therefore, destabilized alumina, zirconia, and zirconia toughened alumina (ZTA) slurries were spray dried and the obtained granules were used to fabricate green and finally sintered bodies for evaluation. Granules made in a laboratory spray dryer with a two-fluid nozzle served as a reference. An ultrasonic atomizer was integrated into the same spray dryer and the influence on the granule properties was evaluated. Untapped bulk density, granule size distribution, and flowability are among the evaluated granule-related properties as well as the granule yield which is used as an indicator of the process efficiency. Yield and flowability as most important granule properties are clearly improved when atomization is realized with ultrasound. The investigated sinter body properties include porosity, sinter body density, and biaxial strength and are as well positively affected by switching the atomization technique to ultrasound. Therefore, the approach to improve the compressibility of granules by ultrasonic atomization, which leads to an improved microstructure, density, and strength of sintered bodies, has proven to be successful for single-component ceramics (alumina and zirconia) as well as for the multicomponent ceramic ZTA.     

纳米ZrO2-微米Al2O3复合陶瓷中"内晶型"结构的形成与机理

考察了不同烧结状态的氧化错增韧氧化铝陶瓷(zirconia—toughened alumina,ZTA)的晶粒长大与“内晶型”形成的关系。烧结过程中,ZTA陶瓷中晶粒生长与温度、保温时间、第二相ZrO2含量有关,其中温度的影响最为显著。第二相粒子有沿主晶相晶界移动聚集的趋向。内晶结构的形成机理可概括为第二相粒子被夹在主相两晶粒之间不能移动,在随后的主晶相长大过程中,两晶粒共同晶界发生迁移或晶粒“合并”,将第二相粒子纳入晶粒内部。而没有被主相颗粒挤住的可移动的第二相粒子则聚集成较大的晶问第二相颗粒。     

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。     

Formation Mechanism of Hydrous-Zirconia Particles Produced by Hydrolysis of ZrOCl2 Solutions

The secondary particle size of hydrous-zirconia fine particles that have been produced by the hydrolysis of various ZrOCl₂ solutions, with and without the addition of NH₄OH or HCl, was measured using transmission electron microscopy to investigate the effects of the H+ and Cl−ion concentrations on the formation of secondary particles. The average secondary particle size of hydrous zirconia increased as the H+ion concentration increased, attaining a maximum of 200 nm at an H−ion concentration of 0.44 moldm-3. Further increases in the H+ion concentration then caused a decrease in the average particle size. The present experimental results revealed that the secondary particle size of hydrous zirconia is controlled primarily by the concentration of H+ ions that are produced during hydrolysis. The formation mechanism for the secondary particles in hydrous zirconia was determined on the basis of the present experimental results.     

不同工艺制备的水合氧化锆凝胶之特性

用水解沉淀法和中和沉淀法两种工艺制备了水合氧化锆凝胶，并与经乙醇脱水处理后的水合氧化锆凝胶的形貌、热性能、相态以及红外吸收光谱作了比较。     

Al2O3增强ZrO2陶瓷的制备及性能研究

本文采用热分解法制备Al2O3微粉、化学共沉淀法制备(Y,Ce)—ZrO2超细粉,通过适当工艺制备出ZrO2／Al2O3复合陶瓷。经研究发现,添加Al2O3,可抑制ZrO2晶粒的长大,提高基体的强度和韧性。当Al2O3含量达到30%(质量分数)时,复合陶瓷的抗弯强度为986MPa,断裂韧性为13.7MPa*m1／2。材料性能的提高可归结为Al2O3颗粒的弥散增韧和ZrO2陶瓷的相变增韧叠加作用的结果。     

Phase transition and interface evolution of Al2O3/ZrO2 particles in plasma-sprayed coatings

Alumina and zirconia ceramic particles exhibit high hardness and excellent wear resistance at high temperature, and hence are used as ceramic reinforcement phases in some plasma sprayed coatings. In this study, the interface evolution of a zirconia/alumina eutectic ceramic and the phase transition of zirconia in a plasma-sprayed coating were investigated. Scanning electron microscopy and transmission electron microscopy combined with focused-ion beam and energy dispersive X-ray were used to analyze the microstructure and composition of the ceramic interface. The results showed that the eutectic ceramic particles consisted of alumina (outer) and columnar zirconia (inner) before and after the plasma spraying process. The inner zirconia part showed the martensitic transformation of t-type zirconia to stripe-like m-type zirconia. After the plasma spraying, the interface between alumina and zirconia changed significantly, which formed a new oxide layer. The phase transition mechanism in the ceramic particle and oxide layer formation mechanism at the alumina/zirconia interface were investigated.     

溶胶-悬浮液混合制备ZrO_(2(n))-Al_2O_3纳米复合陶瓷

采用微波加热水解氧氯化锆及醇水混合液体,制得ZrO_2前驱物——纳米水合氧化锆溶胶。讨论了反应液体中氧氯化锆浓度和醇/水比对生成物平均粒度及其分布的影响;得出了采用聚甲基丙烯酸铵作为电空间稳定剂的亚微米级氧化铝水悬浮液的稳定条件;阐述了溶胶-悬浮液混合制备复合陶瓷的工艺过程。