氧化锆陶瓷凝胶注模成形研究

试验采用高纯超细氧化锆粉伴为原料,通过凝胶注模成形工艺,获得氧化锆陶瓷刀具的坯体。参照已有经验,通过研究氧化锆陶瓷凝胶注模成形工艺流程及工艺参数与所得样品的关系,进行探索性试验。通过对比试验结果,获得最佳工艺参数,确定了氧化锆凝胶注模成形的最佳配方。按照试验提供的原料配方,严格控制干燥过程和烧成制度,可以得到结构致密、性能稳定、强度较高的陶瓷刀具,为凝胶注模成形方法的工业化推广提供了可靠的参考依据。     

Al2O3/YSZ离位复合及性能研究

采用水基料浆注模、凝胶离位复合法制备Al2 O3 /YSZ材料 ,工艺关键是高质量水基料浆的配制、注模和凝胶固化的物理—化学过程的控制。研究结果表明 ,Al2 O3 与YSZ几乎不固溶 ,Al2 O3 主要作为第二相存在于YSZ晶界 ,Al2 O3 可有效抑制YSZ晶粒长大 ,从而提高了YSZ的强度。     

凝胶注模成型制备Sialon陶瓷的研究进展

本文系统阐述了凝胶注模成型制备Sialon陶瓷的研究与进展,根据凝胶来源分成非水基凝胶注模体系和水基凝胶注模体系,介绍它们的工艺过程和原理。最后提出了凝胶注模成型制备Sialon陶瓷目前应当注意的问题,并展望了它的前景。     

水基凝胶注模法制备稳定氧化锆坯体的研究

采用水基凝胶注模法制备稳定氧化锆坯体，测试其气孔分布，并与干压成型法制备的坯体在密度、强度和形貌上进行比较。结果表明，水基凝胶注模法制备的坯体微观结构较为均匀，气孔分布范围较窄，颗粒分布好，团聚少，坯体强度和密度较干压法高。随固相体积分数的增加，水基凝胶注模法坯体密度逐渐增加，但强度逐渐降低。     

氧化锆陶瓷的凝胶注模成型研究

研究了氧化锆陶瓷凝胶注模成型工艺中单体、引发剂、固相含量、固化温度对料浆的凝胶固化时间的影响及坯体在干燥、烧成中的影响因素.     

凝胶注模成形氧化锆陶瓷性能研究

笔者以氧化锆陶瓷浆料,采用凝胶注模法制备氧化锆坯体,并对其坯体和烧结体进行性能分析。     

凝胶注模成形氧陀锆陶瓷性能研究

笔者以氧化锆陶瓷浆料,采用凝胶注模法制备氧化锆坯体,并对其坯体和烧结体进行性能分析。     

反应烧结碳化硼/碳化硅凝胶注模成形工艺的研究

以碳化硼颗粒为增强相,采用凝胶注模成形工艺制备反应烧结B_4C/SiC复合材料。通过对低粘度、高固相含量碳化硼、炭黑和碳化硅浆料的制备技术以及凝胶注模成形工艺参数的研究,制备出了结构均匀、致密度高的反应烧结碳化硼/碳化硅复合陶瓷。并分析了碳化硼、炭黑和碳化硅料浆制备过程中不同碳化硅颗粒级配、碳化硼含量和碳化硼颗粒大小、球磨时间、料浆pH值、固相含量对料浆粘度的影响。     

注凝成型工艺对熔融石英陶瓷生坯的制备研究

采用了水基注凝成型工艺制备熔融石英陶瓷生坯,凝胶体系为甲基丙烯酸羟基乙酯/三羟甲基丙烷三丙烯酸酯,研究制备高固相、低粘度、流动性好的料浆,研究生坯成型的影响因素如:p H值、固相含量、分散剂等。实验结果表明:当制备的料浆固相含量为60%,pH=4,分散剂为1.5wt%时,可获得高固相含量、良好流动性、低粘度、稳定分散的陶瓷料浆,这是是注凝成型生坯的最关键性步骤。     

ZrO2表面改性及凝胶注模研究

凝胶注模成型工艺能够制备出高强度,高致密性,且形状复杂的氧化锆陶瓷.粉体团聚对凝胶注模成型工艺存在不良影响,粉体团聚导致陶瓷内部产生缺陷,导致致密性、均匀性变差,力学性能降低.本文通过对氧化锆粉体表面改性,改善粉体团聚,将改性粉体用于凝胶注模成型,制备出低粘度浆料.通过SEM、粘度仪、显微镜等仪器,对强度、粘度及粉体分...     

氧化铝陶瓷原位注凝成形技术的研究

本文以研究氧化铝陶瓷的水基注凝成形工艺为目的,详细研究了单体含量、固相含量、浆料陈腐时间对浆料粘度、生坯弯曲强度的影响,以及聚乙二醇对抑制坯体表面起皮的作用。结果表明：坯体的弯曲强度与单体含量成正比;控制氧化铝质量分数在70%可满足制备高固相分数、低粘度浆料的要求;浆料陈腐15h左右对降低浆料粘度、提高坯体强度有明显的效果;浆料中引入2.5wt%的PEG,坯体表面的起皮现象得到有效抑制,但坯体弯曲强度有所降低。     

结构陶瓷的新型凝胶注模成型技术研究与进展

凝胶注模成型是一种先进的陶瓷成型方法,为高性能复杂形状陶瓷的制备提供了有效的技术途径.凝胶注模常用的体系为丙烯酰胺,但由于丙烯酰胺单体具有神经毒性,因此限制了其应用范围.近十余年来无毒体系凝胶注模成型技术受到了国内外学者的广泛重视.本文综述了无毒性凝胶大分子的种类,凝胶成型的基本原理、工艺过程及国内外最新研究成果.这种无毒性凝胶体系具有环境友好、有机物含量少、坯体均匀等优点,将成为今后凝胶注模成型发展的一个重要方向.     

The hydrolysis process of γ-AlON powder and preparation of highly transparent ceramics with aqueous gel-casting

The untreated γ-AlON powders were proposed to prepare highly transparent γ-AlON ceramics by aqueous gel-casting technique and two-step sintering process. The related mechanism of hydrolysis of γ-AlON powders was discussed. The surface of the synthesized γ-AlON powders is covered with a layer of aluminum hydroxides compound. As the period of hydrolysis extends, the surface layer dissolved, and the boehmite and bayerite gradually formed, which is characterized by various techniques including XRD, FT-IR, XPS and TEM. The low viscosity slurry with high solids loading (53 vol%) was obtained by γ-AlON powders without any surface modification treatments as a result of the slow hydrolysis process. In addition, compared with the dry pressed sample, the sample (4.12 mm in thickness) prepared by aqueous gel-casting exhibits superior in-line transmittance of 81–83% in the visible region, which could be ascribed to the more homogenous and denser microstructure of the green body. Finally, the Weibull modulus and characteristic strength of γ-AlON transparent ceramic were determined to be 4.85 and 295 MPa, respectively.     

复杂形状中空陶瓷部件的凝胶注模成型

通过仔细设计模具,并在研究了催化剂等对凝胶注模成型过程的影响以及脱模和干燥对成型坯体质量的影响的基础上,制备出了强度在24MPa以上、外观质量很好的复杂形状中空陶瓷部件。扫描电镜分析可知坯体的显微结构均匀,坯体比较致密,高聚物通过三维网络把陶瓷颗粒紧密地联结在了一起。     

Preparation of porous Y2SiO5 ceramics with high porosity and extremely low thermal conductivity for radome applications

It is well known that aqueous gel-casting is challenging to prepare high-porosity ceramics due to the considerable drying shrinkage, cracking, and deformation of green bodies during drying caused by the high surface tension of water. Porous Y₂SiO₅ ceramics with high porosity were prepared by introducing carbon fibers as a support material in the drying process of aqueous gel-casting to reduce shrinkage during drying. Burning out the carbon fibers after drying does not negatively affect the properties of the porous ceramic. As prepared green bodies by aqueous gel-casting have low shrinkages of 8.69%–6.81% during drying processes and high compressive strength of 13.73 ± 1.55–10.66～0.49 MPa. The higher compressive strength of the green body has a positive significance for processing porous ceramics into special-shaped structures. As prepared porous Y₂SiO₅ ceramics have high porosity of 73.94%–87.71%, lightweights of 1.16–0.55 g?cm³, extremely low thermal conductivities of 0.134 ± 0.006 to 0.051 ± 0.001 W?m^?1?k^?1, relatively low dielectric constants of 2.34–1.58, and tan δ are lower than 1.25 × 10^?3. Porous Y₂SiO₅ ceramics with excellent dielectric properties and thermal insulation properties meet the requirements of thermal insulation and wave transmission integration of radome materials. Aqueous gel-casting also enriches the preparation methods of high-porosity Y₂SiO₅ ceramics.     

Effect of mullite phase formed in situ on pore structure and properties of high-purity mullite fibrous ceramics

Porous mullite ceramics are potential advanced thermal insulating materials. Pore structure and purity are the main factors that affect properties of these ceramics. In this study, high performance porous mullite ceramics were prepared via aqueous gel-casting using mullite fibers and kaolin as the raw materials and ρ-Al₂O₃ as the gelling agent. Effects of addition of mullite fibers on the pore structure and properties were examined. The results indicated that mullite phase in situ formed by kaolin, and ρ-Al₂O₃ ensured the purity of mullite samples and mullite fibers bonded together to form a nest-like structure, greatly improving the properties of ceramic samples. In particular, the apparent porosity of mullite samples reached 73.6%. In the presence of 75% of mullite fibers, the thermal conductivity was only 0.289 W/m K at room temperature. Moreover, the mullite samples possessed relatively high cold compressive strength in the range of 4.9–9.6 MPa. Therefore, porous mullite ceramics prepared via aqueous gel-casting could be used for wide applications in thermal insulation materials, attributing to the excellent properties such as high cold compressive strength and low thermal conductivity.     

Influence of Silicon Nitride (Si3N4) on Mechanical and Dielectric Properties of a Novel Fused Silica Ceramic Composites

Silicon - Porous fused silica (SiO2) ceramic composites were fabricated using a novel gel-casting process and the experiments were conducted using Response Surface Methodology (RSM) central...     

注凝成型工艺的研究进展

介绍了陶瓷的注凝成型工艺原理、工艺流程、浆料分散机理、凝胶固化过程和素坯干燥理论,分析了pH值、分散剂、固相含量及粉体特性对注凝成型浆料流变性能的影响,指出了陶瓷注凝成型工艺的发展趋势及存在的问题。     

Gelcasting of dense and porous ceramics by using a natural gelatine

An improved gel-casting procedure was successfully exploited to produce porous ceramic bodies having controlled porosity features in terms of mean pore size, total pore volume as well as pore geometry. The gel-casting process in which a natural gelatine for food industry is used as gelling agent was firstly set-up to prepare dense alumina and zirconia components. Then, commercial PE spheres, sieved to select proper dimensional ranges, were added to the starting slurries as pore-forming agent. Both alumina and zirconia porous bodies were then produced, having a porosity ranging between 40 and 50 vol%. The fired components were characterised by spherical pores surrounded by highly dense ceramic walls and struts, having a homogeneous and fine microstructure. Their mean pore size was directly dependent on the sieved fraction of the starting PE spheres selected as pore-forming phase.