人造湿磨法云母粉在丁腈橡胶中的应用

采用机械共混的方法研究了人造湿磨法云母粉代替部分炭黑用于丁腈橡胶的补强效果.结果表明:在研究范围内,人造湿磨法云母粉对丁腈橡胶的硫化特性和耐油性能没有明显的影响,对硫化胶有一定的补强作用,能提高其曲挠性能和耐热老化性能,德墨西亚曲挠次数从0.8万次可增加至4.6万次,老化后拉伸强度保持率从86%可提高到99.1%,但耐磨性能和高温压缩永久变形性能稍微下降.     

Physico-mechanical and Surface Wear Assessment of Magnesium Oxide Filled Ceramic Composites for Hip Implant Application

Silicon - In the present study, applicability of ceramic composites as ceramic-on-ceramic hip prostheses is explored. Hence, ceramic composites containing zirconium oxide, silicon nitride, chromium...     

Rheology and Processability of Natural Rubber Composites with Mica

This work is concerned with the influence of mica in natural rubber compounds on properties such as Mooney viscosity, processability and rheological behavior. The amount of this filler was varied from 0 to 40 phr and the stabilized and totalized torques, specific and mechanical energies were determined in a HAAKE torque rheometer. The elastic torque (S′) and complex dynamic viscosity (η?) were measured on a rubber processing analyzer (RPA). The results show that mica influences processability and rheological properties, by acting as a processing agent in natural rubber composites.     

Nucleation of Solid-State Reactions between Nickel Oxide and Aluminium Oxide

The initial stages of the solid-state reaction between high-quality thin films of nickel oxide and single-crystal aluminum oxide have been investigated. Thin films were grown on specially cleaned and annealed basal-plane (0001) alumina substrates by pulsed-laser deposition. The thin-film reaction couples were then heat-treated in air at 1080° and 1100°C for different times in order to induce the formation of the nickel aluminate spinel. The reaction couples were characterized in cross section by high-resolution scanning electron microscopy and conventional transmission electron microscopy. The films of nickel oxide consisted of two twin variants with a common {111} plane, parallel to the basal plane of alumina, but rotated by 60° or 180° about the 〈111〉 direction normal to that plane. The spinel nucleated where the twin boundaries in the nickel oxide film met the alumina substrate and contained the same twin variants as the original NiO film.     

连续纤维增强陶瓷基复合材料合成技术及发展趋势

作为结构材料,陶瓷具有耐高温能力强、抗氧化能力强、硬度大、耐化学腐蚀等优点,然而呈现脆性,不能承受剧烈的机械冲击和热冲击等缺点,严重影响了它的实际应用。为此,人们通过采用连续纤维增韧方法改进其特性,研发出连续纤维增强陶瓷基复合材料。本文综述了陶瓷基连续纤维增强复合材料的制备方法,分析了各种工艺的优缺点。在总结了现阶段连续纤维增强复合材料研究中存在的问题基础上,提出了今后连续纤维增强复合材料的主要研究方向。     

金属间化合物/陶瓷基复合材料的制备工艺与研究进展

金属间化合物材料具有许多优良的性能,可以将金属间化合物与陶瓷材料相复合形成金属间化合物/陶瓷基复合材料.金属间化合物/陶瓷基复合材料是近年来发展起来的一种新型复合材料,制备的金属间化合物/陶瓷基复合材料具有很多优异的性能.本文主要介绍金属间化合物/陶瓷基复合材料的制备工艺和力学性能以及研究进展,研究和开发的金属间化合物/陶瓷基复合材料主要包括Fe-Al金属间化合物/陶瓷复合材料,Ti-Al金属间化合物/陶瓷复合材料和Ni-Al金属间化合物/陶瓷复合材料.本文对金属间化合物/陶瓷基复合材料未来的发展趋势进行了分析和预测.     

Ceramic Properties of Samarium Oxide and Gadolinium Oxide; X-Ray Studies of Other Rare-Earth Oxides and Some Compounds

Samarium oxide forms a ceramic of medium strength and density (6.0) when it is fired at 1300°C. When it is fired at 1500°C., its density is increased to 7.4 but it loses its stability toward boiling water. X-ray data are given concerning the structure of the oxide as received and at 1300°C. and of the reaction product of Sm203 with water. Gadolinium oxide forms a ceramic of somewhat higher density (7.0) at 1300° than does Sm₂O₃; at 1500°C. its density is slightly higher (7.6) whereas its stability toward water is unchanged. Data concerning both oxides include density, shrinkage, moduli of elasticity and of rupture, linear thermal expansion, differential thermal analysis, and specific heat as well as X-ray data. Results are given of a brief survey of the reaction products obtained when Sm₂O₃ and Gd₂O₃ are heated at 1500°C. in equimolecular quantities with Al₂O₃, BaO, CaO, CdO, Fe₂O₃, HfO₂, MgO, SO₂, SrO, ThO₂, and ZrO₂. X-ray data for the following rare-earth oxides as received and after calcination at 1400°C. are given: ceria, praseodymia, neodymia, europia, dysprosia, holmia, erbia, thulia, and ytterbia.     

Synthetic Mica Investigations: IV, Dielectric Properties of Hot-Pressed Synthetic Mica and Other Ceramics at Temperatures up to 400°C.

The dielectric properties of hot-pressed synthetic mica were studied in comparison with those of other ceramic insulating materials with special attention to the variation of these properties with temperatures up to 400° C. Power-factor and dielectric-constant measurements were made at 1 mc., and the volume resistivity was determined on a d.-c. resistance bridge with a voltage of 22.5. The comparison revealed the importance of evaluating the electrical properties of a dielectric material at the temperature at which the insulator is expected to operate. A plot of the power-factor data against the reciprocal of the absolute temperature did not permit the results to be represonted by two intersecting straight lines, as has been previously reported.     

包覆天然云母粉填充聚丙烯复合材料的界面和性能

采用聚丙烯(PP)-马来酸酐(MAH)接枝物(PP-g-MAH)对天然云母粉进行包覆后制备出PP/包覆天然云母粉复合材料,并对材料的界面形态和包覆云母粉用量与材料的力学性能、加工性能及耐热性的关系进行了研究.结果表明,包覆云母可以有效改善复合材料中云母与基体的界面结合程度,减少缺陷的出现.随包覆云母用量的增加,除材料的断裂伸长率相应降低外,材料的屈服强度、弹性模量和冲击韧性都有较明显的提高,可达到同时增强增韧的目的.另外,包覆云母的使用还可以改善材料的加工流动性与维卡软化点.     

Investigation of the Physical and Mechanical Properties of Hot-Pressed Boron Nitride/Oxide Ceramic Composites

Billets of hexagonal boron nitride powders ( h -BN) were hot-pressed, varying the alignment of the platelike particles and the amount of oxide additives. Increasing either alignment of individual grains or the amount of additives was shown to increase flexural strength, to approximately 120 MPa at ambient temperatures. h -BN was shown to deflect cracks initially propagating normal to its basal planes.     

Interface Reactions between Silicon Dioxide-Lead Oxide Glass and Manganese Zinc Ferrite

The interface reations between SiO₂–PbO melt and Mn-Zn ferrite were studied using electron probe microanalysis (EPMA) and X-ray diffraction (XRD). Intermediate layers were formed at the interface between the glass and the Mn-Zn ferrite which were heated at 800° and 900°C, although those layers were not found in specimens heated at 1000°C. Using EPMA and XRD, the intermediate layers were found to be Pb₂(Mn, Fe)₂Si₂O₉ and Pb₈(Mn, Fe)Si₆O₂₁. The mechanisms of interface reactions are discussed, related to glassforming regions. It was concluded that the interface reaactions between SiO₂–PbO melt and Mn-Zn ferrite are controlled by the dissolution of Zn ions and Mn ions from the Mn-Zn ferrite.     

Reactions between α-Silicon Carbide Ceramic and Nickel or Iron

The interactions of very pure and practically 100% dense α-SiC with nickel and iron at 850°C were investigated. Large reaction zones, consisting of carbon and silicides of Ni and Fe, were examined by microprobe analysis. By means of marker experiments, the diffusion mechanisms were investigated: only Ni and Fe migrate through the reaction layer. Isothermal sections of the ternary phase diagrams Ni-Si-C and Fe-Si-C at 850°C are presented.     

碳纤维增强碳化硅陶瓷基复合材料的研究进展及应用

碳纤维增强碳化硅陶瓷基复合材料具有密度低、高强度、高韧性和耐高温等综合性能,已得到世界各国高度重视.本文综述了碳纤维的研究进展,C_f/SiC复合材料的制备方法,并分析了各种制备方法的优缺点.概述了C_f/SiC复合材料作为高温热结构材料和制动材料的应用状况.最后,指出了有待解决的问题和今后的主要研究方向.     

菲的精制工艺及其氧化产物的利用

简述了菲的物理化学性质和存在形式,介绍了菲的提取、精制方法,详细地介绍了工业中常用的两种精菲生产工艺:双溶剂结晶法和蒽油双溶剂萃取法,并简述了菲的氧化产物菲醌、联苯二甲酸的利用。     

Diffusion and Convection in Reactions of Slag with Porous Ceramic Bodies

Reactions between slag and porous ceramic bodies in the CaO-SiO₂-Al₂O₃ system at 1450°C were investigated. Varying rates of slag absorption and differences in the manner of precipitation of anorthite (CaAl₂Si₂O₈) were observed. The results are rationalized in terms of mass transport in the liquid phase. Local viscosities of melts are particularly important in the interpretation.     

Unique Opportunities for Microstructural Engineering with Duplex and Laminar Ceramic Composites

Duplex (two-phase) microstructures and laminar composites offer some unique opportunities for improving the room-temperature mechanical reliability (e.g., flaw tolerance) and the high-temperature microstructural stability (e.g., resistance to grain growth and creep damage) of structural ceramic materials. Examples illustrating the approach to designing novel multiphase microstructures and laminar composites with enhanced structural reliability are given. These are based on current work on various alumina-based ceramics as well as zirconia-, silicon nitride-, and silicon carbide-containing ceramics. Critical issues and areas for future work are discussed.     

Fabrication and Properties of Ceramic Composites with a Boron Nitride Matrix

Boron nitride (BN) matrix composites reinforced by a number of different ceramic fibers have been prepared using a low-viscosity, borazine oligomer which converts in very high yield to a stable BN matrix when heated to 1200°C. Fibers including Nicalon (SiC), FP (A1₂O₃), Sumica and Nextel 440 (Al₂O₃-SiO₂) were evaluated. The Nicalon/BN and Sumica/BN composites displayed good flexural strengths of 380 and 420 MPa, respectively, and modulus values in both cases of 80 GPa. On the other hand, FP/BN and Nextel/BN composites exhibited very brittle behavior. Nicalon fiber with a carbon coating as a buffer barrier improved the strength by 30%, with a large amount of fiber pullout from the BN matrix. In all cases except for Nicalon, the composites showed low dielectric constant and loss.