Carbon-ceramic Composites Research Articles

Effect of fiber orientation on tribological properties of fiber‐reinforced C/C–SiC composites mated with ceramic ball

AbstractCarbon fiber–reinforced SiC ceramic matrix composites (C/C–SiC composites) with advantages of high wear resistance and corrosion resistance are of high application potential as ceramic bearings. In this study, the frictional and wear behaviors of C/C–SiC with different fiber orientations mating with Al2O3 and SiC balls, respectively, have been investigated. Results reveal that fiber orientation effectively affects the friction and wear properties of carbon–ceramic composites in paired friction experiments with ceramic balls. In comparison to C/C–SiC with unidirectional fiber orientation, C/C–SiC pads with randomly arranged fibers exhibited a more stable coefficient of friction and lower volume wear, presenting the best performance among the pads considered herein, which may have the potential to be applied to bearing materials. The factors affecting the formation of continuous tribo‐film, which influence the comprehensive performance, are researched. It is proposed that the amount of wear debris and the formation of SiC/SiC micro‐hard frictional pairs may inhibit or promote the formation of continuous friction film. The dominant wear mechanisms for friction pairs of C/C–SiC and ceramic are abrasive wear and oxidation wear.

Ion-Beam Surface Modification of Carbon Fibers

Carbon fibers are used in the production of automobiles, airplanes, sporting goods, energy, and biomedicine due to their unique properties such as high specific strength, high specific tensile strength, low coefficient of thermal expansion, and low density. The research and development of both the technology of carbon fibers production and their modification for a wide range of applications have been and remain relevant. The summary of the accumulated experience in the modification of carbon fibers shows that ion-beam treatment allows to obtain a variety of geometry of the developed surface topography, in particular, whisker-shaped and corrugated oriented across or along the fiber. Such processing compares favorably with ordinary fiber whiskering both by a variety of geometry of the composite interface, and by the absence of the problem of whisker-fiber adhesion. Ion-beam treatment also makes it possible to modify the surface layer structure from amorphized to ordered with different degrees of graphitization. Irradiation with chemically active ions leads to functionalization of carbon fiber due to formation, for example, of nitrides and carbon oxides. The choice of nitrogen ions for the technology of carbon-carbon and carbon-ceramic composites seems to be more preferable due to less stringent requirements for the temperature of the irradiated fiber. For ion-beam corrugation of polyacrylonitrile-based carbon fiber surface, only its heating above the temperature of dynamic annealing of radiation damage is required. The use of helium ions in technological plasma acceleration systems leads to a significant efficiency increase in ion-beam processing.

Electrical conduction mechanism in carbon-ceramic composites

Carbon-ceramic composites (C/Cer) have been prepared by chemical vapor deposition of coal tar pitch onto clay substrates and characterized by thermogravimetric analyses, powder X-ray diffraction, Raman spectroscopy, and scanning and transmission electron microscopies (SEM and TEM). The study of the dc electrical conductivity, together with the determination of the Hall voltage sign, proves that such C/Cer composites are n-type semiconductors. Our results demonstrate that: 1) the mechanism of electrical conduction of C/Cer semiconductors proceeds through the pathways expected for amorphous solids (ie. variable-range hopping and heat-activated pathways at low and high temperatures, respectively); and 2) their transport properties are strongly dependent on the clay components, as evidenced by microscopy experiments.

Assessment of machined surface for SiCf/SiC ceramic matrix composite during ultrasonic vibration-assisted milling-grinding

As a new advanced material, silicon carbon fiber-reinforced silicon carbon ceramic matrix composite has attracted increasing attention and would have a promising application in prospect owing to its superior properties such as low density, high strength, and high-temperature resistance. However, there is still no such standard criterion for machined surface quality evaluation of fiber-reinforced ceramic matrix composites or fiber-reinforced composites. Thus, in this paper, investigations have been performed on ultrasonic vibration-assisted milling-grinding SiC fiber-reinforced SiC-based ceramic matrix composite. It aims to propose a primary criterion for the machined surface assessment of fiber-reinforced composites. This study considered and tested fiber-reinforced composites such as SiCf/SiC CMC, Cf/SiC CMC, and CFRP. Due to the large size of pits and voids in the machined surface, it was recommended to use non-contact measuring equipment for surface quality measurement. The 2D surface roughness value of every single machined surface differed much along different measuring directions and regions. Then, the 3D surface roughness was suggested for describing the machined surface quality as its data fluctuation was much more minor than the 2D roughness. The comparative analysis found that the measuring area size significantly influenced the 3D roughness result. This study used a measuring area of 13 × 13 mm2, 11 × 11 mm2, 7 × 7 mm2 for SiCf/SiC CMC, Cf/SiC CMC, and CFRP, respectively, taking into consideration the measuring time consumption and the reliability of measured data.

Asymmetrical Damage Aspects Based Investigations on the Disc Brake of Long-Range UAVs through Verified Computational Coupled Approaches

In recent years, the use of unmanned aerial vehicles (UAVs) has increased significantly. Asymmetrical factors, or frictional studies on the disc brake of UAVs, are one of the safety considerations taken into consideration during the design process because UAVs and their components have been built with the best safety in mind. This study focuses on choosing the optimal material for a UAV’s disc brake by using transient structural and thermal models. In order to compare the asymmetry-based frictional force produced by the two ways; the processes used in the transient simulation are validated using pin-on-disc (POD) testing. The foundation for this validation investigation is a metal matrix composite made of an aluminum alloy, and the basis tool is an ASTM G99-based computational test specimen. Steel-EN24 and carbon ceramic matrix composites testing are expanded using the same POD tests. A range of 3 percent to 8 percent error rates is found. As a result, the calculation techniques are applied to the UAV’s disc brake after they have proven to be trustworthy. This fixed-wing UAV’s extensions have a 5 kg payload capacity. The weight, avionics components, tire dimensions, and disc brake dimensions of the other UAV design parts are calculated using analytical formulas. The final designs are made using CATIA as a result. The grid convergence experiment is organized using a traditional finite element analysis tool. Finally, at its maximum rotational speed, a UAV’s disc brake is put through asymmetrical friction testing based on structural and thermal consequences. The correct materials for critical applications, such as carbon fiber-woven-wet-based reinforced polymer and Kevlar unidirectional-49-based reinforced polymer composites for changing rotating speeds, have now been made possible by fixed-wing UAVs.

Influence of synergistic strengthening effect of B4C and TiC on tribological behavior of copper-based powder metallurgy

High-speed rail brake pads mainly face the lack of stability of tribological performance under high temperature. An effective approach that is often employed is to reinforce copper-based powder metallurgy (PM) with single ceramic particle to obtain superior properties. In this paper, preparation of the dual ceramic particles (B4C–TiC) reinforced copper-based PM by powder metallurgy route, and paired as friction discs using the self-made carbon-ceramic composite. Influence of synergistic strengthening effect of B4C and TiC on tribological behavior and wear mechanisms were investigated. The result reveals that the more content of TiC (less 5%) in B4C–TiC, the greater the performance improvement, especially when the ratio of TiC/B4C is 5:3, the copper-based PM obtains exceptional mechanical and thermal performance, but different tribological behavior at different braking speed. The main factor affecting the tribological behavior at middle-speed (4500 rpm) is TiC, while is B4C at high-speed (6000 rpm) due to the generation of B2O3 tribo-film. With the ratio of TiC/B4C increases, the generation of B2O3 tribo-film goes through a change of first increased to the maximum, and then disappeared. While wear mechanism of copper-based PM goes through the transitional stage from abrasive wear to slight oxidative wear, severe oxidative wear, abrasive wear and adhesive wear, respectively.

The effects of double ceramic particles (B4C-SiC) on the performance, microstructure, and friction-wear mechanisms of copper-based PM

The copper-based powder metallurgy reinforced by double ceramic particles (B4C-SiC) were prepared by powder metallurgy route and the self-made carbon-ceramic composite was used as the friction disc. The effects of different proportions B4C-SiC on performance, microstructure, and friction-wear mechanisms were examined. The result reveals that the presence of SiC (less 3%) in B4C-SiC has great promotion effect on mechanical-properties, but small weakened effect on thermal-performance. The main factor affecting the friction-performance at low-speed is SiC, while is B4C at high-speed. With the ratio of SiC/B4C increases, the formation of B2O3-tribo-film experiences a change of first-decreased, then-increased, and finally-disappeared. While wear-mechanism experiences the transition stage from abrasive wear to slight fatigue wear, abrasive wear, severe fatigue wear, and adhesive wear, respectively.

Transient investigation of nozzle erosion in a long-time working hybrid rocket motor

Nozzle erosion is a common problem in a hybrid rocket motor with the passive thermal protection structure. Nozzle profile and erosion rate distribution are changing with time due to the chemical erosion. Serious erosion greatly influences the performance of the hybrid rocket motor. This paper is aimed to analyze the characteristics of nozzle erosion during the firing process. For this purpose, an unsteady numerical model of carbon-based nozzle erosion is established. The thermochemical erosion of nozzle is simulated coupled with the flow field. A dynamic grid technique is adopted to simulate the regression process of the nozzle surface. Based on this model, numerical simulations on a hydrogen peroxide(HP)/hydroxyl-terminated polybutadiene (HTPB) hybrid motor have been performed in a long-time working process. To validate the numerical results, a full-scale hybrid rocket motor is tested. The simulated nozzle erosion rate is about 0.069 mm/s in the steady state simulation, which agrees well with the test data (0.072 mm/s). The material properties of the carbon ceramic composite are affected by the high-temperature gas and suffering performance degradation in the firing process. Both of the combustion chamber pressure and oxidizer to fuel ratio have great influence on the erosion rate.

Synthesis and characterization of carbon–silicon carbide particulate composites by powder metallurgical route

AbstractCarbon–silicon carbide composites have been prepared using powder metallurgical route. Phenolic resin, cokes, silicon powder, and silicon carbide in varying amounts were dry mixed and co‐ball milled. The co‐ball milled powders were then compacted and cured simultaneously in hot press. The compacted blocks were carbonized at 1000°C and further heat‐treated at 1400°C in an inert atmosphere. Silicon carbide was formed in carbon–ceramic composites due to the reaction of silicon with carbon matrix during heat treatment at 1400°C. The densities of the final carbon–ceramic composites obtained were in the range of 1.66–1.83 gm/cm3 with open porosities of 2–7%. Scanning electron microscopy and X‐Ray diffraction were used to characterize the microstructures and compositions, respectively, of the composites processed at 1000 and 1400°C. It is found that the sintered composites consist of β‐SiC with particle size varying from 1 to 5 μm. Mechanical strengths of the composites were found to be highly dependent on the percentage of silicon carbide formed due to the reaction of silicon with carbon matrix at 1400°C. Friction coefficient, measured by pin‐on‐disc method, was found to be higher for 1400°C heat‐treated composites as compared to 1000°C heat‐treated composites due to formation of SiC.

Анализ комбинированного радиационно-кондуктивного теплообмена при деструкции пористого углерод-керамического композиционного материала тепловой защиты

Carbon-ceramic composites are considered promising materials to be used in thermal protection shields of innovative descent vehicles that are currently being designed. The development of thermal shield material requires modelling its thermal-phase state under operational conditions. In this paper, physical and mathematical models are proposed for analysis of the destruction and radiation-conductive heat transfer in a porous carbon-ceramic composite material consisting of carbon fibres covered by silicon carbide. The models take into account all main physical and chemical processes of heating up and thermo-chemical destruction. A software package DMA based on the finite element method was developed, and modelling of heating up and destruction of the material was conducted. It was established that when the temperature was above 800 °С, the contribution of the radiation heat exchange became considerable. A comparison of the surface microstructures obtained through modelling and gas-dynamic testing in a plasmatron facility showed their qualitative agreement, while the mass loss did not exceed 16%.

Разработка структурно-функциональной модели технологического процесса изготовления углерод-керамических композитов методом пропитки расплавами

В статье рассмотрены принципы использования процессов жидкофазной технологии для решения задач научно-технического прогресса и использования передовых технологий. В ходе ознакомления с методами моделирования был выбран метод IDEF3 как наиболее оптимальный для решения поставленных задач. Разработаны модели технологического процесса получения углерод-керамического композиционного материала методом пропитки расплавами, которые не были представлены ранее в литературных данных. Представлены рекомендации по практическому использованию полученных результатов работы. The article discusses the principles of using liquid-phase technology processes to solve the problems of scientific and technological progress and the use of advanced technologies. During familiarization with the modeling methods, the IDEF3 method was chosen. The developed models of the technological process for producing a carbon-ceramic composite material by the method of impregnation with melts, which were not previously presented in the literature. Recommendations on the practical use of the results are presented.

Development of carbon-ceramic composites employing SiC and graphite as reinforcement with phenolic matrix

Development of carbon-ceramic composites employing SiC and graphite as reinforcement with phenolic matrix

Prolonging the Cycle Life of a Lithium-Air Battery by Alleviating Electrolyte Degradation with a Ceramic-Carbon Composite Cathode.

Carbon materials with a high specific surface area are usually preferred to construct the air cathode of lithium-air batteries due to their abundant sites for oxygen reduction and discharge product growth. However, the high surface area also amplifies electrolyte degradation during charging, which would become the threshold of cyclability after addressing the issue of electrode passivation and pore clogging, but is usually overlooked in relevant research. Herein, it is proven that the critical influence of cathode surface area on electrolyte consumption by adopting carbon-ceramic composites to reduce the surface area of the air cathode. After screening several potential ceramic materials, an optimal composite of Ketjenblack (KB) and La0.7 Sr0.3 MnO3 (LSM) delivered a discharge capacity that was even higher than that of pure KB. This composite effectively mitigated the parasitic reaction current by 45 % if polarized at 4.4 V versus Li+ /Li. Correspondingly, this composite prolonged the cycle life of the cell by 156 %. The results demonstrate that electrolyte consumption during charging is one of the critical boundary conditions to restrain the cyclic stability of lithium-air batteries.

A Study on the Laser-Assisted Machining of Carbon Fiber Reinforced Silicon Carbide.

In recent years, as replacements for traditional manufacturing materials, monolithic ceramics and carbon fiber reinforced silicon carbide (C/SiC) ceramic matrix composites have seen significantly increased usage due to their superior characteristics of relatively low density, lightweight, and good high temperature mechanical properties. Demand for difficult-to-cut materials is increasing in a variety of area such as the automotive and aerospace industries, but these materials are inherently difficult to process because of their high hardness and brittleness. When difficult-to-cut materials are processed by conventional machining, tool life and quality are reduced due to the high cutting force and temperatures. Laser-assisted machining (LAM) is a method of cutting a workpiece by preheating with a laser heat source and lowering the strength of the material. LAM has been studied by many researchers, but studies on LAM of carbon–ceramic composites have been carried out by only a few researchers. This paper focuses on deducing the optimal machining parameters in the LAM of C/SiC. In this study, the Taguchi method is used to obtain the major parameters for the analysis of cutting force and surface roughness under various machining conditions. Before machining experiments, finite element analysis is performed to determine the effective depth of the cut. The cutting parameters for the LAM operation are the depth of cut, preheating temperature, feed rate, and spindle speed. The signal to noise (S/N) ratio and variance analysis (ANOVA) of the cutting force and surface roughness are analyzed, and the response optimization method is used to suggest the optimal machining parameters.

Microstructure Characterization by X-Ray Computed Tomography of C/C-SiC Ceramic Composites Fabricated with Different Carbon Fiber Architectures

The microstructure morphologies have been characterized by high resolution laboratory X-ray computed tomography in Carbon Fiber Reinforced Carbon and Silicon Carbide (C/C-SiC) ceramic composites fabricated by Gaseous Silicon Infiltration (GSI) from C/C preforms of three different architectures: 3D stitched cloth fabric; 3D orthogonal woven fabric; and needled short-cut felt. Each composites’ microstructure was influenced by the structure of the C/C preform. By incorporating tomography with gravimetric analysis, the 3D distribution of the SiC was visualized, showing a connected SiC network in the needled short-cut felt, and more heterogeneous SiC formation on the surfaces of the fiber bundles in the stitched and woven fabrics. The needled short-cut felt provided the largest contact surface for the GSI reaction and generated ~56% volume fraction of SiC, which is almost twice and three times that achieved in the stitched and woven fabrics respectively. Differences in the open and closed pore distributions were also measured by mercury intrusion porosimetry and tomography.

OPERATING CAPACITY OF ANTI-OXIDIZING COATING IN HYPERSONIC FLOWS OF AIR PLASMA

In this paper, we present the results of investigations of degradation processes that occur in the structure promising high-temperature anti-oxidizing of heat-resistant coating of the Si–TiSi2–MoSi2–B–Y system in hypersonic flows of air plasma. The coating is designed to protect a wide range of heat-resistant materials (carbon–carbon and carbon–ceramic composites, coal–graphite materials, alloys based on Nb, Mo, W, etc.). It is found that the coating operating capacity at surface temperatures [Formula: see text] 1820–1830∘C is provided by the structural-phase state of its microcomposite main layer and formation on the coating surface of a heterogeneous passivating protective film. It is based on borosilicate glass reinforced by rutile microneedles. The mechanism of coating destruction at [Formula: see text] 1850–1860∘C is erosion loss of oxide film as well as generation and growth of gas-filled cavities at the “coating main layer–oxide film” interface. As the pressure of saturated vapor of gaseous oxidation products (SiO, CO, MoO3 and B2O3) exceeds that of the ambient, the oxide film integrity is disrupted and oxidation process becomes active. The rates of erosion loss and sublimation grow as operating temperature increases and ambient pressure decreases.

Properties of wear rate and electrical conductivity of carbon ceramic composites

Properties of wear rate and electrical conductivity of carbon ceramic composites

Development of Elements of Reusable Heat Shields from a Carbon–Ceramic Composite Material 1. Theoretical Forecast

For the new generation of space vehicles with a reusable heat shield, it is promising to use carbon-ceramic composite materials resistant to powerful heat flows arising by the descent of such a vehicle in the atmosphere. This paper presents the results of the theoretical forecast of characteristics of a heat shield from a porous carbon–ceramic composite made on the basis of testing specimens of this composite on a gas-dynamic stand simulating real operating conditions of the heat shield. Methods have been developed for simulating the heating and ablation of specimens of carbon–ceramic composites under their convective heating in a plasmatron. It has been established that the diameter of the nozzle of the gas-discharge channel of the plasmatron and its distance to the frontal surface of the specimen influence the temperature regime of tests. We propose an experimental procedure for attaining a temperature of 273 K on the frontal surface of a cylindrical specimen of a carbon–ceramic composite material of diameter 70 mm and height 70 mm.

Fabrication of low specific resistance ceramic carbon composites by colloidal processing using glucose as soluble carbon source

Ceramic carbon composites were fabricated by colloidal processing using glucose as soluble carbon source. Glucose is converted into conducting carbon at high temperature treatment. Ceramic carbon composites were sintered in flowing argon at \(1400{^{\circ }}\hbox {C}\) showing resistor behaviour even at low carbon content (1 wt%). In this work, ceramic carbon composites were fabricated using alumina–clay slurries with addition of glucose as a soluble carbon source. Morphology of the sintered samples was characterized by field emission gun (FEG) electron microscopy. Phase analysis was done by X-ray diffraction (XRD). Electrical properties of ceramic carbon composites were measured by broad band dielectric spectrometer. Carbon produced from glucose at high temperature was characterized independently by BET surface area, dynamic light scattering, field emission gun scanning electron microscopy, field emission gun transmission electron microscopy, XRD and Raman spectroscopy.

In situ-growth of silica nanowires in ceramic carbon composites

An understanding of the processing and microstructure of ceramic–carbon composites is critical to development of these composites for applications needing electrically conducting, thermal shock resistant ceramic materials. In the present study green compacts of carbon ceramic composites were prepared either by slurry processing or dry powder blending of one or more of the three — clay, glass, alumina and carbon black or graphite. The dried green compacts were sintered at 1400 °C in flowing argon. The ceramic carbon composites except the ones without clay addition showed formation of silica nanowires. The silica nanowire formation was observed in both samples prepared by slip casting and dry powder compaction containing either carbon black or graphite. TEM micrographs showed presence of carbon at the core of the silica nanowires indicating that carbon served the role of a catalyst. Selected area electron diffraction (SAED) suggested that the silica nanowires are amorphous. Prior studies have reported formation of silica nanowires from silicon, silica, silicon carbide but this is the first report ever on formation of silica nanowires from clay.