A Review on Wear and Friction Performance of Carbon-Carbon Composites at High Temperature (original) (raw)
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Influence of thermal properties on friction performance of carbon composites
Carbon, 2001
Three different needled felt C / C composites containing from 5 to 25% fiber oriented normal to the friction surface (z-fiber) were evaluated and tested for friction performance. A laboratory dynamometer was used to simulate cold taxi, hot taxi and normal landing braking events utilizing a single stator and rotor pair. Temperatures measured near the friction surface were lowest for highest thermal diffusivity material demonstrating the effectiveness of z-fiber content at reducing friction surface temperature. Low friction coefficient (|0.12) under cold taxi conditions increased by a factor of two under hot taxi conditions due to water-desorption transitions. Composites with high diffusivity needed greater braking power to experience transition relative to lower diffusivity materials. Higher braking power was needed to produce a transition under higher humidity conditions. Highest z-fiber content discs showed the lowest wear rate which was attributed to higher in-plane shear strength. The wear rate was highest under hot taxi conditions and it was concluded that mechanisms other than oxidation loss were primarily responsible for the wear rate of the C / C composites tested in this study. The C / C composite surfaces had a polished appearance suggesting that the removal of nano-scale particles occurs from the friction process.
Wear, 2009
Due to their thermo-mechanical performances maintained at high temperature, C/C composites demonstrate their advantages in high energy aeronautical braking. During friction a typical tribological behavior was observed. At first, an abrupt transition of friction coefficient takes place systematically from a weak value (∼0.15) to a high value (∼0.35). Before this transition, an extremely weak wear rate is associated to a weak friction coefficient value and no gas exchanges occur in the contact, this regime being called non-reactive. From the abrupt transition, a very high wear rate and strong gas exchanges associated to the high friction value occur (reactive regime). In this paper, for a better understanding of the mechanisms governing the abrupt transition during C/C composites tribological, mechanical, thermal and physicochemical data are analyzed. Friction tests are performed on a 3D C/C composite consisting of PAN-based fibers and CVI pyrocarbon matrix in using a pin-on-disc tribometer equipped with a mass spectrometer allowing the in situ gas exchange analysis (CO 2 production, O 2 consumption) in the contact. To follow the disc surface temperature evolution before, during and after the transition, a thermal infrared camera is used. After friction, worn surfaces and interfaces are characterized by optical microscopy and scanning electron microscopy. In a final analysis, a mechanism is proposed to explain the abrupt transition.
Fiber–matrix unbonding and plastic deformation in C/C composites under tribological loading
Wear, 2010
Carbon/carbon composites exhibit specific tribological behaviour during friction, i.e. the friction coefficient and wear rate decrease as temperature in the contact increases. In order to better understand the wear mechanisms involved at low and high temperatures, friction experiments were performed under air on a tribometer in disc-on-disc configuration and the worn surfaces were characterized at different length scales by OM, SEM and AFM techniques. It was seen that the high wear rate occurring at low temperature was due to severe mechanical abrasion. Worn and scratched surfaces were observed, with the presence of fiber-matrix unbonding and broken and torn-out fibers and the formation of high amounts of third body, demonstrating the fragile behaviour of the C/C composite at low temperature. On the contrary, the low wear rate obtained at high temperature was due to a soft mechanical process, since the main phenomena observed were pyrocarbon matrix exfoliation and expansion and plastic deformation of Z-fiber surfaces, modifying the stress field close to the rubbed surfaces. This involved the detachment of small particles, leading to smooth surfaces.
Comparative Study of Friction and Wear of Two Generation of CVI CC Composite
The physical changes in the braking material due to wear will reduce the brake lifetime and change both the material properties and braking capacity. Humidity has great effects on the coefficient of friction and wear. In this study the wear and friction behavior of a new and old generation of carbon-carbon composite were investigated. Identical samples were tested on a subscale dynamometer at different humidity, environment, and operating conditions. The friction coefficient was recorded and wear was measured. Visual examination, surface topography characterization, microscopy and spectroscopy techniques were used to determine the friction and wear mechanisms. Scanning Electron Microscopy, Raman Spectroscopy, and X-Rays were also used. The change in wear and friction coefficient with energy input were studies and wear transitional zones were detected. It is shown that friction, and wear are dependant on bulk material properties, environment (humid, dry and inert) and the produced friction film. It was shown that the relative humidity has strong influence on the tribological behavior of the old and new generation of composites. Wear and friction transitional zones were detected for both type of Composite.
Impact Abrasive Wear Response of Carbon/Carbon Composites at Elevated Temperatures
Tribology Letters, 2010
Three types of carbon/carbon composites were fabricated using pitch as matrix material. Performance of these composites was evaluated under continuous impact abrasion tests (CIAT). Towards this purpose, a novel testing equipment was designed and developed at AC 2 T. Tests were carried out at room temperature and 500°C. The angle of impact was chosen to be 45°and 90°. Analysis of tribological performance was carried out by mass loss. Characterization of the worn surface was done by means of scanning electron microscopy (SEM) and optical 3D profilometry. In this work, it was shown that wear rates are higher for 45°impact angle compared to 90°for all composites investigated. Fibre debonding and fibre pull out was observed to be the dominating wear mechanisms for these composites during CIAT procedure under normal impact abrasion. Removal of chunk of material contributes to wear under oblique impact abrasion.
Internal friction behavior of carbon–carbon composites
Carbon, 2000
The fundamental internal friction behavior of carbon-carbon composites is studied. Two internal friction mechanisms are proposed according to the special internal friction characteristics in carbon-carbon composites. A thermoelastic mechanism, which is independent of amplitude, mainly leads to the internal friction increase with increasing frequency. The other is a static hysteresis mechanism that internal friction depends on the amplitude but is independent of frequency. Moreover, it is very interesting that some abnormal internal friction phenomena can be observed. The variation characteristics of internal friction and dynamic modulus versus temperature in carbon-carbon composites are quite different from other materials. This special behavior may be a result of interfacial CTE effects, as well as the coordination effects of the individual response of the fibers, matrix and interface of carbon-carbon composites. Finally, the validity of internal friction analysis methods for densification process monitoring and non-destructive inspection of carbon-carbon composites is discussed for the first time. The results indicate that internal friction testing methods have great potential for monitoring process and inspecting components of carbon-carbon composites non-destructively.
Journal of Egyptian Society of Tribology, 2023
Aircraft brakes are very critical for its safe operation. During landing, the brakes takes 40% of the energy while aerodynamic brakes, reverses thrust and rolling friction takes the rest of energy, [1]. Thus superior tribological behavior at high temperatures is required to carry out this mission. Carbon fiber reinforced Carbon(C/C) composites have outstanding low density and high thermomecanical properties, [2]. For these reasons, more aircraft manufacturers convert to C/C brakes. The tribological behavior of C/C composites is examined in this paper by exploring the parameters that affect weight loss. The Taguchi method is used to conduct a design of experiment (DOE) to optimize the experiments size. The response surface methodology is utilized to ascertain the most favorable blend of process operating parameters. The Carbon/Carbon composite's wear and friction characteristics were evaluated using a dry sliding wear test, employing the disc-ondisc method. The findings revealed that the duration of contact between the stator and rotor discs was the most significant contributor to weight loss, followed by the applied load and rotational speed. The most predominant factor was the braking pressure then the time and vehicle speed. KEYWORDS Carbon/carbon composites, taguchi method, analysis of variances, carbon/carbon tribology.
C/C-SiC Composites for Advanced Friction Systems
Advanced Engineering Materials, 2002
Ceramic Matrix Composites (CMC), based on reinforcements of carbon fibres and matrices of silicon carbide, show superior tribological properties in comparison to grey cast iron or carbon/carbon. In combination with their low density, high thermal shock resistance and good abrasive resistance, these Si-infiltrated carbon/carbon materials, called C/SiC or C/C-SiC composites, are promising candidates for advanced friction systems. Generally, the carbon fibres lead to an improved damage tolerance in comparison to monolithic SiC, whereas the silicon carbide matrix improves the wear resistance compared to carbon/carbon. In combination with new design approaches cost-efficient manufacturing processes have been developed and have lead to successfully tested prototypes of brake pads and disks, especially for passenger cars and emergency brake systems.
Characterizations of C/C composites and wear debris after heavy braking demands
Carbon, 2009
Carbon/Carbon disks worn by a reduced scale braking test were characterised by an experimental set-up allowing the analysis of the whole disk. In this way, the structure and the surface chemistry of the wear debris formed during the braking and trapped at the sliding interface were determined. The evolution of the surface chemistry and the structure during rubbing at different braking energies were studied by temperature programmed desorption with mass spectrometry analysis and by measuring the active surface area. The analysis of the composites before and after rubbing highlights the formation of highly disordered and oxygen-rich carbon wear debris at the sliding surface. The surface chemistry of the carbon dust trapped on the disk surface was found to be very similar to that of the wear debris ejected during braking. From this similarity a rough estimation of the amounts of carbon dust lying on the worn composites surface was made. (C. Vix-Guterl). C A R B O N 4 7 ( 2 0 0 9 ) 8 5 -9 3 a v a i l a b l e a t w w w . s c i e n c e d i r e c t . c o m j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / c a r b o n
The Influence of Carbon Fiber Heat Treatment Temperature on Carbon-Carbon Brakes Characteristics
Carbon letters, 2013
The effects of heat treatment temperature (HTT) of polyacrylonitrile-based carbon fiber (CF) on the mechanical, thermal, and tribological properties of C/C composites were investigated. It was found that HTT (graphitization) of CF affects the thermal conductivity and mechanical and tribological characteristics of C/C composites. Thermal treatment of fibers at temperatures up to 2800°C led to a decrease of the wear rate and the friction coefficient of C/C composite-based discs from 7.0 to 1.1 μm/stop and from 0.356 to 0.269, respectively. The friction surface morphology and friction mechanism strongly depended on the mechanical properties of the CFs. The relief of the friction surface of composites based on CFs with final graphitization was also modified, compared to that of composites based on initial fibers. This phenomenon could be explained by modification of the abrasive wear resistance of reinforcement fibers and consequently modification of the friction and wearing properties of composites. Correlation of the graphitization temperature with the increased flexural and compressive strength, apparent density, and thermal conductivity of the composites was also demonstrated.