低温烧结钒和钨掺杂钛酸锌介电陶瓷的相转变

采用化学法结合传统的氧化物固相烧结法制备钛酸锌陶瓷.研究了原料形态和掺杂V2O5和WO3对钛酸锌陶瓷相稳定性、显微组织以及低温烧结行为的影响,讨论了相转变机制和低温烧结机制.研究表明:以V2O5和WO3作为烧结助剂降低陶瓷的烧结温度,钛酸锌陶瓷的低温烧结行为对所选取的原料极为敏感,TiO2的活性对陶瓷低温烧结行为的影响大于ZnO.V2O5和WO3的掺入使钛酸锌陶瓷的烧结温度降至900℃以下,但同时降低了六方相ZnTiO3的分解温度;V2O5和WO3掺杂具有不同的烧结机制,前者主要是液相烧结机制,后者主要是固相反应烧结机制.掺杂导致的相分解和生成的异相降低了陶瓷的介电性能.     

原材料与钛酸铝陶瓷性能之间关系的研究

用不同纯度的二氧化钛粉体和不同晶型的氧化铝粉体为原料进行钛酸铝合成研究。结果表明:引入稳定剂和烧结助剂,在一定的烧结温度条件下,这些原材料均可生成具有良好力学性能的钛酸铝陶瓷;在相同的烧成条件下,钛黄粉反应生成的钛酸铝陶瓷比钛白粉反应生成的陶瓷具有更好的力学性能;采用钛黄粉与工业氧化铝粉合成的钛酸铝陶瓷,由于生产成本低,在耐火材料领域具有广泛的应用潜力。     

钛酸铝固溶体陶瓷的制备与性能

用工业级原料采用固相反应法合成了钛酸铝固溶体[Al2(1-0.2)Mg0.2Ti1 0.2O5].研究了氧化镁(MgO)在钛酸铝(Al2TiO5)结构中的固溶对粉体合成的影响,通过测量Al2(1-0.2)Mg0.2Ti1 0.2O5陶瓷的体密度、热膨胀系数和抗弯强度,进一步研究了其烧结行为、热膨胀行为和机械性能.结果表明:由于MgO的固溶,在相对较低的温度(1 300℃)煅烧便合成纯相Al2(1-0.2)Mg0.2Ti1 0.2O5粉体,并且具有良好的烧结活性.用1 380℃合成的粉体,经1 450℃保温4h烧结的Al2(1-0.2)Mg0.2Ti1 0.2O5陶瓷,不仅具有低膨胀特性,而且有足够高的抗弯强度.     

添加剂对钛酸镁陶瓷性能影响的研究进展

综述了添加剂对钛酸镁陶瓷性能影响的研究现状,烧结及介电性能等方面的进展。研究结果中可以看出,Bi2O3-V2O5、Co2O3、ZnO等氧化物及氧化物玻璃料的添加可以不同程度地大幅降低陶瓷的烧结温度。在Mg2TiO4中掺杂不同添加剂可适当改变其介电常数,满足其介电常数材料的应用需要;在MgTiO3中掺入不同添加剂可不同程度改变其介电常数,得到具有较高Q*f值且τf≈0的钛酸镁基陶瓷材料。从当前研究现状可以看出,掺杂改性是获得所需性能材料的强有力手段,也是今后对钛酸镁基陶瓷性能优化的主要研究方向之一。     

钛酸铝陶瓷及其改性研究

钛酸铝陶瓷作为一种重要的抗热震材料,集低热膨胀率和高熔点于一体。本文从钛酸铝陶瓷的结构、性能、常用的添加剂等几个方面,介绍了目前对钛酸铝改性方面的研究以及国内外的研究成果。     

高温耐热陶瓷坩埚的研制

研究了引入莫来石和二氧化锆复合相对钛酸铝陶瓷坩埚的热膨胀影响,借助SEM分析了材料的断 口形貌,从显微结构上解释了Al_2TiO_5基复相陶瓷坩埚热震后的断裂机制和损坏机理。     

钛酸铝陶瓷及其研究新进展

为了总结近年来国内外对钛酸铝陶瓷的最新研究进展,推动钛酸铝的研究,本文综述了钛酸铝陶瓷的易分解和低强度机理,着重介绍了采用添加剂法、复合相法以及新的合成、成形、烧结等工艺改善钛酸铝陶瓷性能方面的研究进展,并对其最新的应用研究进展作出简单的介绍,更在此基础上提出了钛酸铝陶瓷的发展动向。     

高温耐热陶瓷坩蜗的研制

研究了引入莫来石和二氧化锆复合相对钛酸铝陶瓷坩埚的热膨胀影响。借助SEM分析了材料的断口形貌，从显微结构上解释了Al2TiO5基复相陶瓷坩埚热震后的断裂机制和损坏机理。     

钛酸铝烧结材料在日本获工业化

日本明矿陶瓷克服了特殊原料调整技术问题,使工业化生产钛酸铝烧结材料(亦称特殊陶瓷SSR)获得成功。钛酸铝由氧化铝和二氧化钛制得,其烧结体是热膨胀系数低、抗热冲击非常强的陶     

凝胶注模成型技术制备低膨胀钛酸铝陶瓷的研究

研究了钛酸铝陶瓷的水基凝胶注模成型技术,讨论了该工艺中分散剂、固相体积含量、研磨时间与钛酸铝浆料粘度之间的关系,简要介绍了各种技术条件对坯体、烧结体性能的影响,并对坯体、烧结体的显微结构进行了分析.采用此种工艺制备出了具有较低线热膨胀系数(αRT～1000℃<1.0×10-6/k)的钛酸铝陶瓷样品.     

复合添加剂对钛酸铝稳定性的影响

探讨了复合添加剂对Ａｌ２ＴｉＯ５ 烧结性能、抗折强度、热膨胀系数和稳定性的影响，利用ＸＲＤ、ＳＥＭ 等手段分析了材料的物相组成和显微结构。结果表明， 利用复合添加剂在不提高Ａｌ２ＴｉＯ５ 热膨胀系数的情况下，获得了具有较高强度的稳定化Ａｌ２ＴｉＯ５ 。     

莫来石-钛酸铝陶瓷材料性能的研究

用预合成的钛酸铝制备了莫来石-钛酸铝(MT)陶瓷材料,研究了材料组成与其烧结性能、抗弯强度、热膨胀性能及抗热震性的关系。结果表明,随着钛酸铝含量的减少,MT陶瓷材料的抗弯强度提高,热膨胀系数增大,抗热震性降低,但在钛酸铝含量大于43％时,陶瓷材料的强度有所增加,仍保持较低的热膨胀系数,具有良好的抗热震性。     

钛酸铝陶瓷研究现状及其应用

钛酸铝（Al2TiO5）陶瓷具有低热膨胀、高熔点（1860℃）、优良的抗热震性等特点,被公认是制作低压铸造升液管、汽车发动机上排气阀、活塞头等对抗热震和隔热要求较高的组件最为理想的候选材料;然而其难以获得高强度产品及在一定温度范围内易分解的特点又限制了其应用。本文着重介绍了近年来材料工作者在粉料组成及粒度、添加剂、烧结温度等方面改善钛酸铝陶瓷材料性能所做的研究,并对钛酸铝材料的应用做了简要介绍。     

Preparation, Structure, and Properties of Thermally and Mechanically Improved Aluminum Titanate Ceramics Doped with Alkali Feldspar

Aluminum titanate (AT) ceramic materials doped with alkali feldspar ((Na_0.6K_0.4)AlSi₃O₈) have been prepared. These ceramics exhibited high sinterability, large resistance to thermal decomposition, and large flexure strength. The existence of liquid-phase feldspar at sintering temperatures promoted the formation of AT ceramics as the sintering agent. It was considered that silicon ions substituting for aluminum ions at the surface of AT crystal grains lowered the surface energy and hindered the diffusion of Ti⁴⁺ and Al³⁺, giving rise to the large resistance to thermal decomposition. As a result, doping with alkali feldspar was found to effectively improve the mechanical and thermal properties of AT ceramics.     

Sintering behavior and thermal shock resistance of aluminum titanate (Al2TiO5)-toughened MgO-based ceramics

In order to improve the thermal shock resistance of MgO-based ceramics, aluminum titanate (Al₂TiO₅)-toughened MgO-based ceramics were successfully prepared by solid state sintering at 1450 °C and 1550 °C for 3 h starting from MgO and as-synthesized Al₂TiO₅ powders. The effects of various contents of Al₂TiO₅ second phase on the sintering behavior and thermal shock resistance of MgO-based ceramics were investigated. The sintering behavior of sintered samples was evaluated by comparing the relative density, apparent porosity, bending strength, phase composition as well as microstructure. The thermal shock resistance of sintered samples was characterized by using the residual bending strength after three thermal cycles and thermal expansion coefficient. The obtained samples with 10 wt% Al₂TiO₅, which were sintered at 1550 °C for 3 h, showed the highest relative density, lowest apparent porosity as well as optimum bending strength. In addition, the samples added 15 wt% Al₂TiO₅ at 1550 °C with a dwell time of 3 h were the highest residual bending strength and lowest thermal expansion coefficient. It revealed that the enhancement in thermal shock resistance was ascribed to the reduction of thermal expansion coefficient.     

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.     

Microstructural Design of Silicon Nitride with Improved Fracture Toughness: II, Effects of Yttria and Alumina Additives

Significant improvements in the fracture resistance of self-reinforced silicon nitride ceramics have been obtained by tailoring the chemistry of the intergranular amorphous phase. First, the overall microstructure of the material was controlled by incorporation of a fixed amount of elongated ß-Si₃N₄ seeds into the starting powder to regulate the size and fraction of the large reinforcing grains. With controlled microstructures, the interfacial debond strength between the reinforcement and the intergranular glass was optimized by varying the yttria-to-alumina ratio in the sintering additives. It was found that the steady-state fracture toughness value of these silicon nitrides increased with the Y:Al ratio of the oxide additives. The increased toughness was accompanied by a steeply rising R -curve and extensive interfacial debonding between the elongated ß-Si₃N₄ grains and the intergranular glassy phase. Microstructural analyses indicate that the different fracture behavior is related to the Al (and O) content in the ß´-SiAlON growth layer formed on the elongated ß-Si₃N₄ grains during densification. The results imply that the interfacial bond strength is a function of the extent of Al and Si bonding with N and O in the adjoining phases with an abrupt structural/chemical interface achieved by reducing the Al concentration in both the intergranular phase and the ß´-SiAlON growth layer. Analytical modeling revealed that the residual thermal expansion mismatch stress is not a dominant influence on the interfacial fracture behavior when a distinct ß´-SiAlON growth layer forms. It is concluded that the fracture resistance of self-reinforced silicon nitrides can be improved by optimizing the sintering additives employed.     

钛酸铝陶瓷的性能及其应用

本对钛酸铝陶瓷的结构、热稳定性、微裂纹、低热膨胀性、机械强度及应用进行了综合阐述,并对工艺条件及添加剂对钛酸铝陶瓷性能的影响进行了讨论,给出了改善钛酸铝陶瓷性能的方法和途径,最后提出了钛酸铝陶瓷的研究开发方向。     

Recycle of Waste Glass into "Glass–Ceramic Stoneware"

The reuse of soda–lime–silica scrap or waste glasses as additives for traditional ceramics has been investigated extensively in the literature. Although interesting, this solution does not generally allow large quantities of glass to be recycled. This study reports a novel high glass recycle approach that replaces, in the formulation of porcelain stoneware, the feldspar flux with finely powdered glass derived from the melting of different waste products, e.g. lime from fume abatement systems, feldspar mining residues, and scrap soda–lime glass. At an optimized glass/clay ratio, the "glass–ceramic stoneware" samples sinter at 1000°C. The "glass–ceramic stoneware" has a bending strength approaching 90 MPa and a fracture toughness exceeding 2.0 MPa·m^0.5, similar to those of conventional porcelain stoneware, which requires sintering at higher temperatures. The high strength and fracture toughness are attributed to the interaction between the glass and clay residues upon sintering, which allows the development of several different crystalline phases.     

Preparation and Performance Study of Mullite/Al2O3 Composite Ceramics for Solar Thermal Transmission Pipeline

For lowering sintering temperature of mullite/Al₂O₃ composite ceramics for solar thermal transmission pipeline, kaolin, potassium feldspar, quartz, and γ‐Al₂O₃ were used as raw materials to in situ synthesize the composite ceramics with pressureless sintering method. Densification, mechanical properties, thermal expansion coefficient, thermal shock resistance, phase composition, and microstructure were investigated. The experiment results demonstrated that the introduction of potassium feldspar and quartz decreased the lowest sintering temperatures greatly to 1300°C. The optimum sample A3 sintered at 1340°C obtained the best performances. The water absorption, apparent porosity, bulk density, bending strength, and thermal expansion coefficient of A3 were 0.04%, 0.12%, 2.71 g/cm³, 94.82 MPa, and 5.83 × 10^?6/°C, respectively. After 30 thermal shock cycles (wind cooling from 1100°C to room temperature), no cracks were observed on the surfaces of the sample, and the bending strength increased by ?7.96%. XRD analysis indicated that the main phases of samples before and after 30 thermal shock cycles were consistently mullite, corundum, and α‐cristobalite, while the content of mullite increased after thermal shock. SEM micrographs illustrated that the mullite grains growth and micro‐cracks appeared after thermal shock endowed the composite ceramics with excellent thermal shock resistance.