石英陶瓷材料的研究进展

主要介绍了有关石英陶瓷的原料、成型技术、烧结方法、影响石英陶瓷性能的因素以及应用现状和发展前景.     

等静压成型熔融石英陶瓷的研究

介绍了等静压成型熔融石英陶瓷的技术,研究了水分含量、粒径分布、粘合剂的加入量及烧成温度对制品的成型性能、体积密度、弯曲强度和显气孔率等性能的影响.结果表明:当水分含量在0.3%～1.0%(质量分数)之间,粒径分布为双峰分布,PVA加入量为1.5%,最高烧成温度为1250 ℃时,能成功制备出性能优异的熔融石英陶瓷天线罩.     

陶瓷成型加工技术新进展

陶瓷材料以其优异的耐高温?高强度?耐磨损?耐腐蚀等性能和优点被广泛应用在各个领域中。文中介绍了陶瓷成型加工技术的新方式?新特点和新进展。     

熔融石英陶瓷的性能及其应用

介绍了石英陶瓷的性能特点、制备过程及应用领域     

注凝成型技术在制备石英纤维—石英复合陶瓷中的应用

石英具有很好的热稳定性和透波性能，是制备天线罩很有吸引力的材料之一，其最大的缺点是强度较低，本文论述了用注凝成型技术制备出抗拉强度达到39MPa以上，抗弯强度可达70MNPa的石英纤维－石英复合陶瓷的工艺过程，并对其进行了讨论。     

石英陶瓷注凝成型影响因素的研究

介绍了熔融石英陶瓷的注凝成型机理及其工艺过程,分析讨论了影响熔融石英陶瓷注凝成型的主要因素,通过研究确定了合理的制备工艺参数.     

熔融石英陶瓷制备工艺的比较研究

分别介绍了注凝成型和等静压成型熔融石英陶瓷的技术,对两种成型工艺制品的生产周期、烧成制度、制品性能和灯检效果等作了比较.结果表明:等静压成型制品生产周期比注凝成型大大缩短,制品结构均匀,无阴影,性能优异.     

凝胶法制备熔石英纳米复合陶瓷工艺及性能的研究

对凝胶法制备熔石英纳米复合陶瓷的工艺进行了探讨,并对不同工艺参数下的材料性能进行了分析和对比,讨论了影响材料性能的主要因素,寻求其最佳工艺参数.研究结果表明,用凝胶法可以使纳米相粒子均匀分散于陶瓷基体中,并能方便快速制备熔石英纳米复合陶瓷,纳米相引入后明显改善了材料的烧结性能,增加了材料的密度和强度.     

石英陶瓷色斑污染原因分析及解决措施

研究了石英陶瓷在生产过程中出现的一种蓝色色斑．分析和验证了石英陶瓷内表面蓝包色斑产生的原因和机理．并提出了解决色斑问题的技术途径和措施。研究了蓝包色斑对石英陶瓷电性能的影响．准确评价了色斑对石英陶瓷性能的影响规律及影响程度．彻底解决了石英陶瓷色斑污染的问题。     

石英陶瓷烧结过程中氮化硅的影响

本文研究了氮化硅加入物对石英陶瓷性能的影响。结果表明,氮化硅有助于石英陶瓷的烧结,而对烧结温度无影响。烧成在1150℃~1200℃温度范围内,石英陶瓷的强度、体积密度随氮化硅的添加量增大和烧结温度提高而增大,而石英陶瓷的显气孔率随氮化硅添加量的增大和烧结温度的升高而减小。     

高固相、低粘度熔石英陶瓷料浆特性的研究

制备高固相、低粘度、高分散性和稳定性的料浆是原位凝固成型高性能熔石英陶瓷的基础.本文通过研究熔石英颗粒在液相介质中的某些胶体特性,分别讨论了pH值对料浆稳定性和流动性的影响;乳酸对熔石英、水系统的稀释和分散机理;分散剂的用量对胶体性质的调节作用.     

Preparation and properties of fused silica ceramics by Isobam spontaneous coagulation casting

By surface modification with APTMS, spontaneous coagulation casting (SCC) of fused silica based on Isobam was achieved and the possible coagulation and molding mechanism is proposed. Through the interaction between the polar groups on the Isobam molecular chain and the incorporated –NH₂ groups on the surface of the silica particles, Isobam molecular chains were adsorbed on the surface of particles, which initiate the formation of flocs and the solidification of the suspension. The addition of dispersant TMAH results in the hydrolyzation of Isobam, forming more –COO^–, which effectively improves the fluidity and stability of the suspension. Then the zeta potential, rheological properties and coagulation behavior of the suspension were systematically investigated and the fused silica suspension with high solid content (up to 52 vol%), low viscosity and good coagulation properties were prepared at 1.8 wt% TMAH and 0.5 wt% Isobam dosage. After sintering at 1260 °C for 4 hours, the fused silica ceramics (50 vol% solid content) shows a high bending strength of 61.59 MPa, the lowest dielectric loss tanδ of 8.46×10^-4 and the dielectric constant of 3.72. Thus, this work provides a simple and effective method for preparing fused silica and other ceramics with negative surface charge by Isobam SCC.     

石英陶瓷的应用

介绍了石英陶瓷在玻璃行业以外，冶金、化工、航空航天等领域的应用，包括应用的石英陶瓷制品、应用特点及条件。     

浮法玻璃窑炉用熔融石英陶瓷制品的注凝成型研究

介绍了熔融石英陶瓷的注凝成工艺，并通过注凝成型工艺制作出了大规格异型的浮法玻璃窑炉用熔融石英陶瓷产品。     

Erosion Behavior of Gelcast Fused Silica Ceramic Composites

In this paper, the characteristics of solid particle erosion on fused silica ceramics are investigated. Gelcasting, a near net shape forming process, is adopted for the fabrication of ceramics. Three types of ceramics with a combination of pure fused silica, fused silica+5 wt% silicon nitride (Si₃N₄)?+?1 wt% boron nitride (BN) and fused silica+5 wt% silicon nitride (Si₃N₄) +1 wt% alumina (Al₂O₃) are prepared at a constant 52 vol% solid loading, 10 wt% monomer content and 10:1 monomer ratio. Different impingement angles (30^o, 45^o, 60^o and 90^o) and three impact velocities (86 m/s, 101 m/s and 148 m/s) were chosen to examine the behavior of erosion on gelcasted ceramics using SiO₂ particles as erodent. The maximum rate of erosion is obtained at normal impingement angle (90^o), which shows the brittle nature of ceramics. The impact velocity and angle of impingement have an appreciable effect on erosion rate. Resistance to erosive wear is found to have improved with the inclusion of reinforcements in the fused silica ceramics. The erosion rates of different ceramics are compared. Ceramic composite with a combination fused silica+5 wt% Si₃N₄+ 1 wt% BN shows the highest resistance to wear. The surface roughness and morphology of the eroded surfaces have also been studied.

     

Influence of β-Si3N4 whiskers on sintering and crystallization of fused silica ceramics

Fused silica ceramics are widely applied for radome materials, crucibles, and vanes, but the mechanical properties were deteriorated due to the cristobalite crystallization. The fused silica ceramics added with by β-Si₃N₄ whiskers were prepared by a slip-casting method to retard the cristobalite crystallization. The influences of the sintering environments and the β-Si₃N₄ whiskers on the microstructure and phase structure were investigated. The silanol (Si-(OH)_n) and oxygen vacancies (V_O) in the fused silica in formed in different conditions were studied by Fourier Transform Infra-Red (FT-IR) and X-ray photoelectron spectroscopy (XPS), and the results indicated that the ball-milled produced a large amount of the silanol groups onto the surface of the fused silica particles. The fused silica heated in the vacuum created the maximum oxygen vacancies (24.2%) on the surfaces. Silanol groups reacted with the β-Si₃N₄ whiskers, and the O atoms in the silanol groups were fixed into the bulk materials. And the crystallization kinetics and the activation energy of Si₃N_4w/SiO₂ ceramics at the temperature ranging from 1200 to 1400°C were calculated based on the JMA(Johnson-Mehl-Avrami) model. The activation energy of the fused silica ceramics with the addition of the β-Si₃N₄ is 506.2 kJ/mol, increased by 23.6% than that of the pure fused silica ceramic.     

The sound absorption performance of the highly porous silica ceramics prepared using freeze casting method

Highly porous silica ceramics with unidirectional pores were prepared using the freeze casting method. By adjusting the solid content and freezing temperature, the porosity of the ceramics was tailored in the range of 78.20%-84.59% and pore size in the range of 8.4-71.4 μm, respectively. Sound absorption properties of porous silica ceramics was studied and the effect of structural factors was systematically investigated. The results showed that higher porosity and smaller pores of the porous ceramics favored the sound absorption in the entire sound wave frequency. By backing the sample with small pore size porous ceramics, the sound absorption property was enhanced, particularly in the low and medium frequency range, thus the sound absorption peak shifted towards lower frequency. The presence of air gap in the back would also favor sound absorption in low and medium frequency range. The as-fabricated porous silica ceramics owed excellent sound absorption properties due to their unidirectional pores and low flow resistances.     

Fabrication of porous silica with controllable and tunable porosity via freeze casting

Porous ceramics offer unique properties that can bring advances to many application areas. The freeze-casting process has a strong potential for fabricating porous ceramics; however, the effects of process parameters on part porosity must be well understood for scalable manufacturing via freeze casting. This paper presents an experimental analysis of the freeze-casting process that correlates the freeze-casting parameters with pore characteristics. A full-factorial design of experiments is conducted on a unidirectional freeze-casting testbed using silica as the ceramic material and camphene as the solvent. The effects of solid loading, particle size, cooling temperature, and the distance from the cooling surface on porosity characteristics are evaluated. The fabricated samples are cross-sectioned vertically and horizontally and imaged using scanning electron microscopy. Image processing is used to obtain the porosity characteristics of areal porosity, pore size, pore shape, and pore orientation. The capability to steer the pore orientation is also demonstrated through bidirectional freezing experiments supported by a finite-element model. As a result, a quantitative understanding of the effects of freeze-casting process parameters on porosity characteristics is gained for the silica–camphene system. These results and the presented approach can be used for reproducible manufacture of porous ceramics with controlled porosity.     

辊道窑陶瓷辊棒的化学矿物组成与性能研究

选取了三种不同组成的优良陶瓷辊棒对其化学-矿物组成和显微结构特征进行了研究,发现以莫来石为基质结合的刚玉复相材料,具有较高耐高温性能和抗热震性能。刚玉莫来石复相中分别引入适量的MgO,K2O,ZrO2可以更好的改善陶瓷辊棒的显微结构及性能。