连续纤维增强SiC复合材料制备工艺与性能研究进展

综述了国内外碳纤维与碳化硅纤维增强碳化硅复合材料的制备工艺与性能的研究进展,并介绍了其氧化性能及防护措施.认为连续纤维增强SiC复合材料的制备工艺复杂,成本较高,生产周期长,但是如果采用连接技术制备成陶瓷/金属复合构件使用,既有利于降低成本,又能够扩大该先进陶瓷基复合材料的应用范围.目前,国内对连续纤维增强的SiC复合材料与金属(如高温合金等)的连接技术研究较少.     

Interlaminar shear strength of SiC matrix composites reinforced by continuous fibers at 900 °C in air

To reveal the shear properties of SiC matrix composites, interlaminar shear strength (ILSS) of three kinds of silicon carbide matrix composites was investigated by compression of the double notched shear specimen (DNS) at 900 °C in air. The investigated composites included a woven plain carbon fiber reinforced silicon carbide composite (2D-C/SiC), a two-and-a-half-dimensional carbon fiber-reinforced silicon carbide composite (2.5D-C/SiC) and a woven plain silicon carbon fiber reinforced silicon carbide composite (2D-SiC/SiC). A scanning electron microscope was employed to observe the microstructure and fracture morphologies. It can be found that the fiber type and reinforcement architecture have significant impacts on the ILSS of the SiC matrix composites. Great anisotropy of ILSS can be found for 2.5D-C/SiC because of the different fracture resistance of the warp fibers. Larger ILSS can be obtained when the specimens was loaded along the weft direction. In addition, the SiC fibers could enhance the ILSS, compared with carbon fibers. The improvement is attributed to the higher oxidation resistance of SiC fibers and the similar thermal expansion coefficients between the matrix and the fibers.     

Hochleistungsbremsscheiben aus Faserverbundkeramik

High performance brake discs made of fiber reinforced ceramics The Audi AG is one of the worldwide leading car manufacturers of the premium class. One of the main aims of the technical development department at Audi is the use of novel and innovative materials. The Audi AG has intensively worked on the development and introduction of ceramic brake discs for several car types. These brake discs are made of a short carbon fiber reinforced silicon carbide ceramic, a so called CMC‐material (ceramic matrix composite). This material is produced in a very complex process by silicon melt infiltration of carbon preforms. The advantages of these innovative and powerful brake discs out of C/SiC‐ceramic are the low weight and thus the reduction of the unsprung rotating masses, the low wear rate during completed service life, the temperature and fading stability and the corrosion resistance. The complete braking system and its periphery had to be reengineered and adjusted because of the specific material properties.     

Manufacture of a polymer-based carbon nanocomposite as bipolar plate of proton exchange membrane fuel cells

The aim of this paper is to prepare a polymer-based carbon nanocomposite reinforced by carbon fiber cloth (CF) to be utilized as bipolar plate of proton exchange membrane (PEM) fuel cell. For this purpose, some single, double, and triple-filler composites were manufactured by using phenolic resin as polymer (P) and graphite (G), carbon fiber (CF) and expanded graphite (EG) as fillers. The production method was compression-molding technique. The electrical conductivity, flexural strength, toughness, hardness, porosity, and hydrogen permeability tests were then measured to determine the mechanical and physical properties. A triple-filler composite containing 45 wt.% G, 10 wt.% CF, 5 wt.% EG, reinforced by a layer of CF cloth, was selected as composite bipolar plate. The electrical conductivity, thermal conductivity, and flexural strength of this composite were 74 S/cm, 9.6 W/m K, and 74 MPa, respectively, which are higher than the specified value by department of energy in USA (DOE). The composite bipolar plate used in the single fuel cell assembly showed a maximum power density 810 mW/cm². In this paper, a material selection was performed on the different materials of bipolar plates. It can be concluded that the composite bipolar plates are more suitable for high life time stationary applications.     

Tension–compression fatigue of a SiC/SiC ceramic matrix composite at 1200 °C in air and in steam

Tension–compression fatigue behavior of a non-oxide ceramic composite with a multilayered matrix was investigated at 1200 °C in laboratory air and in steam. The composite was produced via chemical vapor infiltration (CVI). The composite had an oxidation inhibited matrix, which consisted of alternating layers of silicon carbide and boron carbide and was reinforced with laminated woven Hi-Nicalon™ fibers. Fiber preforms had pyrolytic carbon fiber coating with boron carbide overlay applied. Tension–compression fatigue behavior was studied for fatigue stresses ranging from 80 to 200 MPa at a frequency of 1.0 Hz. Presence of steam significantly degraded the fatigue performance. Specimens that achieved fatigue run-out were subjected to tensile tests to failure to characterize the retained tensile properties. The material retained 100% of its tensile strength. Composite microstructure, as well as damage and failure mechanisms were investigated.     

Silicon carbide fibre-reinforced resin matrix composites

Resin matrix composites reinforced with silicon carbide yarn and silicon carbide monofilament were fabricated and evaluated. Both composite systems exhibited excellent mechanical properties. Composite thermal expansion behaviour, fibre electrical resistance, and fibre thermal oxidation resistance are also reported. Advantages with respect to carbon fibre-reinforced resins are discussed.     

连续纤维补强增韧碳化硅基陶瓷复合材料研究进展

连续纤维补强增韧碳化硅基陶瓷复合材料具有密度低、强度和韧性高、抗氧化、耐高温等综合性能,已在国外宇航领域得到了广泛的应用.综述了国内外连续纤维补强增韧C/SiC陶瓷复合材料的研究进展,主要包括国内外在增韧机理、基体复合技术、界面技术以及应用等方面的研究进展情况.     

碳纳米管-聚碳硅烷陶瓷先驱体的制备研究

通过化学修饰得到一种改性的碳纳米管,可均匀分散于聚碳硅烷中形成一种碳纳米管掺混的陶瓷先驱体CNT-PCS,实验表明,该CNT_PCS熔体的流动指数大于1,粘流活化能为195．4kJ／mol。该新型先驱体可用于制备高性能碳纳米管增强碳化硅陶瓷材料,也可进行熔融纺丝,以制备碳纳米管增强的碳化硅纤维。     

Mechanical behavior of SiCf/SiC composites with alternating PyC/SiC multilayer interphases

In order to tailor the fiber–matrix interface of continuous silicon carbide fiber reinforced silicon carbide (SiC_f/SiC) composites for improved fracture toughness, alternating pyrolytic carbon/silicon carbide (PyC/SiC) multilayer coatings were applied to the KD-I SiC fibers using chemical vapor deposition (CVD) method. Three dimensional (3D) KD-I SiC_f/SiC composites reinforced by these coated fibers were fabricated using a precursor infiltration and pyrolysis (PIP) process. The interfacial characteristics were determined by the fiber push-out test and microstructural examination using scanning electron microscopy (SEM). The effect of interface coatings on composite mechanical properties was evaluated by single-edge notched beam (SENB) test and three-point bending test. The results indicate that the PyC/SiC multilayer coatings led to an optimum interfacial bonding between fibers and matrix and greatly improved the fracture toughness of the composites.     

Carbon fiber reinforced hafnium carbide composite

Hafnium carbide is proposed as a structural material for aerospace applications at ultra high temperatures. The chemical vapor deposition technique was used as a method to produce monolithic hafnium carbide (HfC) and tantalum carbide (TaC). The microstructure of HfC and TaC were studied using analytical techniques. The addition of tantalum carbide (TaC) in the HfC matrix was studied to improve the microstructure. The microstructure of HfC, TaC and co-deposited hafnium carbide-tantalum carbide (HfC/TaC) were comparable and consisted of large columnar grains. Two major problems associated with HfC, TaC, and HfC/TaC as a monolithic are lack of damage tolerance (toughness) and insufficient strength at very high temperatures. A carbon fiber reinforced HfC matrix composite has been developed to promote graceful failure using a pyrolytic graphite interface between the reinforcement and the matrix. The advantages of using carbon fiber reinforcement with a pyrolytic graphite interface are reflected in superior strain capability reaching up to 2%. The tensile strength of the composite was 26 MPa and needs further improvement. Heat treatment of the composite showed that HfC did not undergo any phase transformations and that the phases comprising composite were are thermochemically compatible.     

单向碳纤维增强碳化硅基复合材料的拉伸试验

采用手工精细加工板状双哑呤拉伸试件,并配以恰当的加强块,避免了因试件较短和加工等引起的夹持段压环,从夹持段拔出及试件在试验段根部破坏等问题,成功地实施了短试件（热压法制备的单向碳纤维增强碳化硅基体复合材料）的拉伸试验,微实时观察表明,由于界面强度非常弱,试件中首先出现因界面破坏而形成的沿纤维方向的裂纹,随着载荷的增加,裂纹数量迅速增多且裂纹均平行于纤维方向,最终,这些平行裂纹横向连接使试件被拉断,因此,对于界面强度过弱的单向纤维增强陶瓷基复合材料不可能产生横向的饱和裂纹。     

Effect of structure of interfacial coating layer on mechanical properties of continuous fiber reinforced reaction sintered silicon carbide matrix composite

A dense silicon carbide matrix composite reinforced by Hi-Nicalon fibers CVD coated with boron nitride and silicon carbide was fabricated by slurry impregnation and subsequent reaction sintering with molten silicon. The effect of the structure and the thickness of the silicon carbide layer of the fiber coating on the mechanical properties of the composite were investigated. That is, three types of silicon carbide layers, namely a dense structure with a thickness of 0.15 m and two porous structures with a thickness of 0.15 m and 0.48 m, respectively, were investigated. As a result, excellent strength property of ceramic matrix composite (CMC) was obtained in the case of the dense silicon carbide (SiC) layer. The thickness effect of the SiC layer on the strength was smaller than that of the structure.     

C/SiC复合材料的制备及性能研究

本文对聚碳硅烷化学转化法制备碳纤维增强碳化硅复合材料的生产工艺进行了研究,探讨了工艺参数对材料性能的影响.研究结果表明,聚碳硅烷分子量是影响材料性能的重要参数,纤维和基体间热膨胀系数的不匹配可通过向基体内加少量二氧化锆进行改善.材料的力学和热学性能测试结果表明,C/SiC复合材料具有较好的综合性能,其断裂韧性比未增强的单一陶瓷提高较多.利用电镜分析了弯曲试样的断口形貌.     

Ceramic thin film thermocouples for SiC-based ceramic matrix composites

Conductive ceramic thin film thermocouples were investigated for application to silicon carbide fiber reinforced silicon carbide ceramic matrix composite (SiC/SiC CMC) components. High temperature conductive oxides based on indium and zinc oxides were selected for testing to high temperatures in air. Sample oxide films were first sputtered-deposited on alumina substrates then on SiC/SiC CMC sample disks. Operational issues such as cold junction compensation to a 0 °C reference, resistivity and thermopower variations are discussed. Results show that zinc oxides have an extremely high resistance and thus increased complexity for use as a thermocouple, but thermocouples using indium oxides can achieve a strong, nearly linear response to high temperatures.     

连续纤维增强SiCf/SiC陶瓷复合材料的发展

连续纤维增强SiCf／SiC陶瓷基复合材料具有良好的高温力学性能、抗氧化性和化学稳定性，是航空航天和核能等领域新的高温结构材料研究的热点之一。回顾了增强体连续SiC纤维的发展，综述了SiCf／SiC材料的成型制备工艺、界面相对力学性能的影响和目前的应用研究，展望了连续纤维增强SiCf／SiC陶瓷基复合材料以后的研究重点及发展前景。     

SiCf/SiC陶瓷复合材料的研究进展

SiCf/SiC陶瓷复合材料具有良好的力学性能、高温抗氧化性和化学稳定性，是航空航天和原子能等领域理想的新一代高温结构材料。本文概述了增强体SiCt的发展状况及存在的问题，对SiCt/SiC材料的制备工艺、界面相的研究状态、材料的损伤破坏机理和目前的应用研究进展做了综述，并分析了SiCf/SiC陶瓷复合材料的研究重点和发展前景。     

Creep Behavior in Interlaminar Shear of a SiC/SiC Ceramic Composite with a Self-healing Matrix

Creep behavior in interlaminar shear of a non-oxide ceramic composite with a multilayered matrix was investigated at 1,200 °C in laboratory air and in steam environment. The composite was produced via chemical vapor infiltration (CVI). The composite had an oxidation inhibited matrix, which consisted of alternating layers of silicon carbide and boron carbide and was reinforced with laminated Hi-Nicalon? fibers woven in a five-harness-satin weave. Fiber preforms had pyrolytic carbon fiber coating with boron carbide overlay applied. The interlaminar shear properties were measured. The creep behavior was examined for interlaminar shear stresses in the 16–22 MPa range. Primary and secondary creep regimes were observed in all tests conducted in air and in steam. In air and in steam, creep run-out defined as 100 h at creep stress was achieved at 16 MPa. Larger creep strains were accumulated in steam. However, creep strain rates and creep lifetimes were only moderately affected by the presence of steam. The retained properties of all specimens that achieved run-out were characterized. Composite microstructure, as well as damage and failure mechanisms were investigated.     

高温氧化气氛下3D C/SiC质量变化率与剩余强度的相关性

通过三维编织炭纤维增强碳化硅基复合材料(3D C/SiC)在各种氧化气氛中的环境实验, 研究了氧化气氛中材料的质量变化率和剩余强度随温度变化规律及其相关性。根据3D C/SiC复合材料各组元的作用, 对其微观组织及炭纤维预制体的氧化损伤演变进行了分析。结果表明, 在各个氧化温度区间内, 3D C/SiC质量变化率与剩余强度随温度变化的规律基本相同, 两者结果相互对应。对于3D C/SiC, 用质量变化率作为对环境损伤敏感性表征的一个基本指标, 比用剩余强度表征更科学可靠。      

Mechanical properties and corrosion behavior of lead-silicon carbide fiber and lead-carbon fiber composites made by electrodeposition

Multifilament silicon carbide fibers (Nippon Carbon, Nicalon type) and carbon fibers (Thornel, Pan T 300 and Pitch type) were used to produce lead-matrix composite materials for battery plate grid applications. Lead was impregnated into the fibers by electrodeposition from fluoborate baths. The electrical conductivity of carbon fibers was sufficient for direct electroplating; silicon carbide fibers were electroless plated with copper beforehand. The experimental conditions for good penetration of lead into the fiber tows were determined.Unidirectional composite samples with a fiber volume fraction of 5 to 25% were prepared from both lead impregnated fiber sheets and rods by hot-pressing (280°C, 50 MPa, 5–30 mm). The flexural strength and modulus of these samples were measured as a function of the infiltration current density and of the fiber volume fraction. Ultimate strengths in the range 300–400 MPa were attained for both lead-silicon carbide and lead-carbon composites, at a fiber volume fraction of about 25%. These latter composites exhibited a good corrosion resistance towards 38.5 wt-% sulfuric acid under non-anodic conditions.     

Comparative study of high temperature composites

Two classes of composite made using either ceramic matrix with high temperature fibers or carbon/carbon have been used for various applications that require high temperature resistance, over three decades. However, their use has been limited to special applications because of the high costs associated with fabrication. Typically the composites are cured at more than 1000°C, and in most instances the heating has also to be carried out in controlled environments. In addition, because of the high processing temperature, only certain type of expensive fibers can be used with the ceramic matrices. A recently developed inorganic matrix, called polysialate can be cured at temperatures less than 150°C, making it possible to use carbon and glass fibers. Composites made using carbon, glass and combinations of carbon and glass fibers have been tested in bending and tension. This paper presents the comparison of processing requirements and mechanical properties of carbon/carbon composites, ceramic matrix composites made with silicon carbide, silicon nitride and alumina fibers and carbon/polysialate composites. The results indicate that carbon/polysialate composite has mechanical properties comparable to both carbon/carbon and ceramic matrix composites at room and high temperatures. Since the polysialate composites are much less expensive, the authors believe that it has excellent potential for more applications in aerospace, automobile and naval structures.