发展中的光纤保护性涂料

本文对发展中的光纤保护性涂料进行了介绍，重点介绍了热固化和紫外光固化两大类光纤涂料的固化原理、组成特性、涂覆工艺及主要性能。     

Conductive, Polypyrrole Coating on Mullite/Alumina Fibers for Electrophoretic Deposition of Oxide Matrices

Mullite/alumina fibers (Nextel™ 720) have been rendered conductive for electrophoretic deposition (EPD) by coating with polypyrrole (Ppy) from an aqueous solution of pyrrole (Py). The polymer coating was characterized by thermogravimetric (TG) analysis, scanning electron microscopy (SEM), and conductivity measurements. The Ppy coating thickness is ∼0.1 μm and the fiber resistance 1–2 (kΩ/cm)/fiber tow. A maximum conductivity of ∼48 S/cm was achieved from a 0.005 M pyrrole solution. A Nextel 720/Al₂O₃ composite was synthesized using Ppy-coated fibers as the cathode in an EPD cell. The green and sintered microstructures of the resultant composites are reported.     

Novel Method for Coating Magnetic Iron Oxide Particles with Carbon Black

Magnetic particles with finer size, higher coercive force, higher blackness, and lower electrical resistance are required to produce better magnetic tape materials. A new method to coat iron oxide particles with carbon black using an adhesive agent is reported in this paper. Magnetic tapes prepared using the coated particles in the recording layer exhibit improvements in both light transparency and electrical resistance. A decrease in transparency of ∼20% and a reduction in electrical resistance of ∼1 order of magnitude relative to conventionally prepared tapes are achieved when ∼5% of the particle weight is carbon black. Surface smoothness and the orientation ratio are also improved because the dispersibility of these particles in magnetic lacquer is better than that of uncoated magnetic iron oxide particles. Higher electromagnetic performance relative to the conventionally prepared layers is also obtained. TEM photographs indicate that all the carbon black is firmly bound to the surface of the magnetic iron oxide particles in a distinct layer.     

Fugitive Interfacial Carbon Coatings for Oxide/Oxide Composites

The effectiveness of fugitive interfacial carbon coatings in Nextel™ 720-based composites was investigated. Dense (>90%) matrix (calcium aluminosilicate, 0° and ±45°) composites and porous matrix (mullite/alumina, eight-harness satin fabric) composites were fabricated and tensile tested in two control conditions (uncoated or carbon-coated) and with the carbon removed (fugitive interface). Results indicated that carbon removal in dense matrix composites did not significantly change unidirectional composite strength, even after long-term exposure at 1000°C. For porous matrix composites, composite strength was independent of the fiber/matrix interface, even after exposure at 1150°C for 500 h in air.     

Fiber Coating Concepts for Brittle-Matrix Composites

The current interest in tough, high-temperature materials has motivated fiber coating development for brittle-matrix composites with brittle reinforcements. Such coatings are needed for controlled interface debonding and frictional sliding. The system investigated in this study was sapphire fiber-reinforced alumina. This system is thermochemically stable for severe use conditions, exhibits little thermal expansion mismatch, and utilizes the excellent strength and creep resistance of sapphire reinforcements. Porous oxide and refractory metal coatings which satisfy requirements for toughness improvement in these composites were identified by employing a variety of newly developed mechanical testing techniques for determining the interfacial fracture energies and sliding resistances.     

硼纤维及其复合材料

在美国第４５届材料与加工工程促进学会年会与展览上,著名的美国ＴＥＸＴＲＯＮ ＳＹＳＴＥＭＳ公司展出了碳化硅纤维、硼纤维及其复合材料等产品。本文简要介绍ＴＥＸＴＲＯＮ ＳＹＳＴＥＭＳ公司硼纤维及其复合材料的现状与发展。     

镀层和氧化膜厚度的显微镜测量技术

对GB/T 6462-2005进行了简单介绍,着重介绍了显微镜法测量镀层和氧化膜厚度的原理、测量仪器和操作步骤、测量不确定度及其控制等,同时对横断面的制备进行了补充说明.该方法的突出特点是直观、重现性好,因而常用于仲裁,或检测精度要求较高的产品和校验其它测厚方法.     

玻璃纤维水性防火涂料的研制

介绍了玻璃纤维水性防火涂料组分的选择,涂料的制备。通过选用硅丙树脂乳液和水性三聚氰胺树脂作为涂料的基料,膨胀型防火体系,季戊四醇和玉米淀粉为成炭剂,磷酸三聚氰胺和高聚合度的聚磷酸铵为催化剂,三聚氰胺为发泡剂,研制一种水性防火涂料。经测试,该涂料在110-120℃成膜后的性能,适用于玻璃纤维防火制品的生产。     

Developments in Oxide Fiber Composites

Prospects for revolutionary design of future power generation systems are contingent on the development of durable high-performance ceramic composites. With recent discoveries in materials and manufacturing concepts, composites with all-oxide constituents have emerged as leading candidates, especially for components requiring a long service life in oxidizing environments. Their insertion into engineering systems is imminent. The intent of this article is to present a synopsis of the current understanding of oxide composites as well as to identify outstanding issues that require resolution for successful implementation. Emphasis is directed toward material systems and microstructural concepts that lead to high toughness and long-term durability. These include: the emergence of La monazite and related compounds as fiber-coating materials, the introduction of the porous-matrix concept as an alternative to fiber coatings, and novel strategies for enabling damage tolerance while retaining long-term morphological stability. Additionally, materials and mechanics models that provide insights into material design, morphology evolution, and composite properties are reviewed.     

吸波纤维研究进展

介绍了目前复合吸波材料中所用的吸波纤维，包括碳纤维、碳化硅纤维、多晶铁纤维等及其改性纤维的吸波机理和性能。简述了吸波纤维在复合材料中的排布方式、长度和含量对材料吸波性能的影响。综述了吸波纤维的研究现状和进展。     

Multilayered Oxide Interphase Concept for Ceramic-Matrix Composites

Hi-Nicalon/SiC minicomposite specimens containing three oxide interphase layers (amorphous SiO₂, monoclinic ZrO₂, and amorphous SiO₂) were prepared by chemical vapor deposition. The minicomposites exhibited graceful composite failure behavior with reasonable load-carrying capability in room-temperature tensile tests. Much of the composite behavior and load-carrying capability was retained even after matrix precracking and subsequent oxidation in air at 960°C for 10 h. In both the as-prepared and oxidized specimens, crack deflection and fiber pull-out occurred preferentially within the multilayered interphase region. The potential merits and uncertainties associated with this multilayered oxide interphase approach were discussed in the context of designing environmentally durable interfaces for ceramic-matrix composites.     

软木纤维增强PP复合材料的研究

采用软木纤维作为增强材料提高聚丙烯性能。为了改善软木纤维和聚丙烯母体之间的相容性,用马来酸酐接枝聚丙烯(MAPP)对软木纤维进行接枝处理,用MAPP或用三元乙丙橡胶(EPDM)对软木纤维进行改性处理。结果表明,与未经处理木纤维的复合材料相比,三种处理方法都使复合材料的热性能、加工性能和力学性能有了较大的提高。用MAPP接枝和用MAPP表面处理木纤维的方法比用EPDM表面处理木纤维的方法在提高复合材料热性能、加工流动性和拉伸强度方面更为显著。用EPDM表面处理木纤维在改善复合材料的冲击强度、断裂伸长率上更明显。此外,木纤维在复合材料中的浓度对复合材料其它性能的影响,以及MAPP接枝木纤维和MAPP处理木纤维的不同实验结果也进行了评价。     

A Novel Technique for Producing Fine Metal Fibers for Enhancing Mechanical Properties of Glass-Matrix Composites

Micrometer-sized refractory metal fibers of Nb were produced by an unconventional method of mechanically reducing arc-cast ingots of Nb-Cu in which the original microstructure contains ductile Nb precipitates. During mechanical reduction the precipitates were elongated into fibers, which were extracted by chemically dissolving the Cu matrix. Composite specimens of Nb fibers in a glass matrix were fabricated by dry-blending a mixture of fibers and powdered glass, then hot-pressing into disks. Fracture toughness, K _{I C} , was measured using microin-dentation and three-point bending methods. The fracture toughness increased with increasing volume fraction of fibers with the greatest improvement noted at 0.10≤ v_f ≤0.20. The values of K _{I C} increased as the interfiber spacing and the fiber diameter decreased. Both the effective fracture surface energy and the fracture strength were enhanced by increasing v_f . The small fibers embedded in the brittle matrix showed virtually no evidence of microcracking; Nb fibers and glass matrices also demonstrated good interfacial adhesion. Fractographs suggested that the fibers were very effective in resisting crack propagation. Experimental observations were explained using the concept of crack-front bowing and fiber bridging.     

Superfast Densification of Oxide/Oxide Ceramic Composites

Superfast densification of ceramic composites in the pseudobinary system Al₂O₃-Y₃Al₅O₁₂ was carried out by using a new technique called spark plasma sintering (SPS). Dense ceramic composites were obtained by heating appropriate powder mixtures to 1573 K in an SPS unit at a rate of 600 K/min. No holding time at 1573 K was applied. Scanning electron microscopy studies showed the compacted materials to contain submicrometer-sized grains of the same sizes as the precursor powder mixtures; i.e., no significant grain growth had occurred.     

异形纤维复合材料研究进展

本文综述了生物复合材料的结构特征和性能特点、复合材料的仿生研究以及异形纤维复合材料的研究发展和应用现状。     

Nanocrystalline Yttria-Stabilized Zirconia Fibers from Plant Fibers and their Polymer Composites

Nanocrystalline zirconia–8-mol% yttria (yttria-stabilized zirconia (YSZ): ZrO₂–8-m% Y₂O₃) fibers have been prepared from aqueous poly vinyl alcohol (PVA)–zirconium oxy nitrate solution and jute (plant fiber). Soluble Zr and Y ions in PVA solution formed a uniform coating on the surface of jute once it dried completely. Slow hydrolysis of zirconium ion with ammonium hydroxide deposited zirconium hydroxide on the jute surface. Decomposition of the dried zirconium hydroxide-coated jute at high temperature (1200°C/2 h) resulted in the formation of single-phase, nanocrystalline cubic-YSZ with the corresponding average X-ray crystallite size 30–35 nm. Heat-treated fibers have been characterized by X-ray diffraction and scanning electron microscopy. We also prepared polymer composites by incorporating chopped, ground YSZ fibers into epoxy matrix and investigated polymer/fiber interface by transmission electron microscopy analysis.     

四种烧蚀复合材料用纤维的对比

对比了T–700碳纤维(T–700 CF),高硅氧玻璃纤维(HSGF),S–2高强玻璃纤维(S–2高强GF),连续玄武岩纤维(CBF)4种纤维的密度和拉伸性能,并采用扫描电子显微镜、X射线荧光光谱,差示扫描量热及热重等测试技术对这4种纤维的表面形貌、化学组成、比热容及热稳定性进行了表征和对比。结果表明,T–700 CF,HSGF,S–2高强GF和CBF 4种纤维的密度由小到大的顺序为T–700 CFHSGFS–2高强GFCBF,拉伸强度由小到大的顺序为HSGFS–2高强GFCBFT–700 CF,T–700 CF的拉伸弹性模量最高,而S–2高强GF的断裂伸长率最高。T–700 CF的直径最小,CBF的表面最粗糙。在相同温度下,200℃以前T–700 CF和CBF的比热容基本一致,200℃以后4种纤维的比热容由小到大的顺序为S–2高强GFHSGFCBFT–700 CF。在相同温度下,4种纤维的失重率由小到大的顺序为CBFS–2高强GFHSGFT–700 CF。     

Surface Modification of Reinforcement Fibers for Composites by Acid Treatments

In this study, we investigated the surface modification of reinforcement fibers for composites by acid treatments, including PBO fiber, Kevlar fiber and carbon fiber. The corresponding changes in the surface free energy components were carefully evaluated using a Cahn dynamic contact angle analysis system. In addition, the fiber's surface elemental composition and topography were studied using X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The results showed that the surface nitrogen-to-carbon (N/C) and oxygen-to-carbon (O/C) ratios were significantly increased after the treatments. The surface free energy of PBO fiber was increased from 43.3 mJ/m² to 58.5 mJ/m² or by 35% with 60 wt% methanesulfonic acid solution treatment for 36 h. However, the increase with 60 wt% nitric acid solution was only by 14% (to 49.5 mJ/m²) for the same treatment time.