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1.
In general polymers are used in the form of composites (fiber reinforced, solid lubricated or both) in tribo-applications,
where they may encounter more than one type of wear situations or mechanisms to different extents. The area of investigating
the optimum concentration of fillers for best combination of tribo-performance in different wear modes and mechanical strength
is sparingly researched. In this paper, research findings on the influence of the contents of short carbon fibers (CF) and
PTFE (particulate form) in Polyamide (PA) 12 on friction and wear behavior in two wear modes (adhesive and fretting) have
been reported. With increase in contents of CF up to 30% (vol) most of the mechanical properties and tribo-performance improved
in adhesive and fretting wear modes. With a view to enhance it further, PTFE was added step by step in the best performing
composite (PA+30% CF). This boosted the tribo-performance further, however, at the cost of strength properties. With increase
in PTFE percentage (10, 15 and 20% by vol), specific wear rate (K
o) and friction coefficient (μ) both decreased appreciably in adhesive as well as fretting wear modes. The composite consisting of 30% CF and 20% PTFE showed
lowest values for μ and K
o rendering it the best tribo-combination for all practical purposes. The abrasive wear behavior of composites was also investigated.
However, wear performance in this mode showed exactly opposite trends. Inclusion of fibers or combination of fibers and PTFE
proved detrimental.
相似文献
J. BijweEmail: |
2.
《Wear》2007,262(5-6):727-735
Three composites were fabricated based on Polyetherimide (PEI) matrix and carbon fabric (CF) (55 vol.%) of different weaves, viz. plain, twill and satin (4H) by impregnation technique. These composites were evaluated for various mechanical properties and tribological performance in low amplitude oscillating wear (LAOW)/fretting wear mode. It was observed that CF reinforcement led to a significant enhancement in all strength and modulus properties of PEI except elongation to break (e). Twill weave proved to be the most effective followed by satin and plain weave in almost all the properties. The LAOW mode evaluation under various loads revealed that the wear performance order was exactly opposite to the above trend. Overall, plain weave composite was the best performer followed by twill and satin. Various wear mechanisms, such as fiber-matrix debonding due to repetitive reciprocating shearing stresses, micro-cracking, micro-cutting and pulverization of fibers followed by removal of debris from the contact zone were operative during such wear situation. Amongst these processes, generation of fiber debris, their temporary retention in fabric weaves and subsequent removal from the crater played a key role in overall wear performance. The ability of plain weave to hold back the debris was maximum that resulted in lowest wear while satin weave had the minimum retention ability that led to the highest wear. The proposed wear mechanisms were supported by SEM studies. 相似文献
3.
Three composites of Polyetherimide (PEI) reinforced with carbon fabric (CF) of three weaves viz. plain, twill and satin-4 H were developed keeping the amount of fabric constant (55% by vol.). Studies on mechanical properties confirmed that the twill weave composite (T) showed the highest strength, modulus (both tensile and flexural) and interlaminar shear strength (ILSS) followed by satin (S) and plain weave (P) composites. The performance order, however, was reverse in the case of toughness and elongation to break. Specific wear rate in a single-pass, unidirectional and un-lubricated abrasive wear mode against SiC paper showed strong influence of weave in mild wear condition (load 10 N). Composite S showed the highest wear resistance (W
R) followed by composites T and P. With increase in load, the difference in performance diminished to the extent that at 40 N, it was almost similar for all the three composites. This was correlated with the difference in the length of the fibers between crossover points which, in turn, allowed the microdisplacement of fibers in the composites during abrasion. This was supported by the SEM.
相似文献
J. BijweEmail: |
4.
Interfacial adhesion between matrix and fiber plays a crucial role in controlling performance properties of composites. Carbon
fibers have major constraint of chemical inertness and hence limited adhesion with the matrix. Surface treatment of fibers
is the best solution of the problem. In this work, cold remote nitrogen oxygen plasma (CRNOP) was used for surface treatment.
Twill weave carbon fabric (CF) (55–58 vol%) was used with and without plasma treatment with varying content of oxygen (0–1%)
in nitrogen plasma to develop composites with Polyetherimide (PEI) matrix. The composites were developed by compression molding
and assessed for mechanical and tribological (abrasive wear mode) properties. Improvement in tensile strength, flexural strength,
and interlaminar shear strength (ILSS) was observed in composites due to treatment. Similarly, improvement in wear resistance
(W
R) and reduction in friction coefficient (μ) were observed in treated fabric composites when slid against silicon carbide (SiC) abrasive paper under varying loads. A
correlation between wear resistance and tensile strength was slightly better than that in Lancaster–Ratner plot indicating
that ultimate tensile strength (S) and elongation to break (e) were contributing to control the W
R of the composites. It was concluded that enhanced adhesion of fibers with matrix was responsible for improvement in performance
properties of composites, as evident from SEM, Fourier Transform Infrared spectroscopy-Attenuated Total Reflectance (FTIR-ATR)
technique. 相似文献
5.
Abrasive wear performance of carbon fabric reinforced polyetherimide composites: Influence of content and orientation of fabric 总被引:4,自引:0,他引:4
Dry abrasive wear performance of five plain weave carbon fabric (CF) reinforced Polyetherimide (PEI) composites, developed with increasing CF contents (in the step of 10 vol%) is reported in this paper. It was observed that composite reinforced with 65 vol% CF (IP65) exhibited the best tensile and shear strength and closely followed the leader (IP75) in flexural strength. IP65 when abraded against silicon carbide paper showed highest wear resistance (WR) and lowest friction coefficient (μ) among all composites. The composites IP85 and IP40 containing highest and lowest amount of CF respectively showed least enhancement in strength properties and poorest wear performance. Parallel studies on the influence of fabric orientation with respect to the sliding plane and direction, on WR showed that when CF was oriented parallel to the sliding plane, it had poorest wear resistance. The performance improved for the composites when fabric was oriented normal to the plane. The parallel or anti-parallel orientation of warp or weft fibers with respect to sliding direction showed marginal changes in friction and wear performance. Wear mechanisms were suggested and strongly supported by worn surface analysis using SEM.Efforts were also done to investigate the wear-property correlation. It was observed that the WR was directly proportional to the product of interlaminar shear strength (Is) and elastic modulus (E). Fairly good linearity was shown for specific wear rate (K0) as a function of factor (μP/IsE) where μ is coefficient of friction and P is the normal pressure (N/mm2). 相似文献
6.
《Wear》2007,262(5-6):749-758
Polyacrylonitrile (PAN) based high strength carbon fabric (plain weave) reinforced polyetherimide (PEI) composites were fabricated using impregnation technique by selecting five different contents of carbon fabric, viz. 85, 75, 65, 55 and 40 vol.%. These bidirectional (BD) composites were evaluated for their mechanical strength as well as tribological behavior in adhesive wear mode. Dry adhesive wear studies were conducted on a custom designed wear tester in which high PV conditions can be simulated. Tests were conducted at various operating parameters such as load, temperature and orientation of fabric with respect to the sliding plane. Two important results were observed; firstly the moderate CF contents (75, 65 and 55 vol.%) proved to be the most effective in manifold increase in mechanical strength of PEI and secondly, the composites with fabric in the direction normal to sliding plane led to very high coefficient of friction (μ). When fabric was parallel to the sliding plane, significant improvement in the tribo-properties of PEI in terms of very high tribo-utility (up to 600 N), appreciably low μ and enhanced wear resistance (WR) (in the range of 10−16 m3/N m) was achieved. The extent of improvement, however, strongly depended on the operating parameters and fabric content. A fairly good correlation was obtained between WR and combination of mechanical properties such as ultimate tensile strength (S), and interlaminar shear strength (ILSS). Wear mechanism studies by SEM supported the observed wear performance of composites. 相似文献
7.
Polyethersulfone (PES) composites were developed with carbon fabric (CF). Cold remote nitrogen oxygen plasma (CRNOP) treatment
was employed to the CF to incorporate functional groups and promote fiber–matrix adhesion. This study includes the effect
of PES melt flow index (MFI) on the wettability of CF and its influence on fretting wear performance. Evaluations of fretting
wear properties of composites led to the conclusion that the CRNOP treatment proved beneficial to enhance performance properties
significantly. Polymer MFI and treatment to CF proved to be the decisive parameters for controlling performance of composites
apart from operating parameters. Perforations on the treated carbon fiber, evidently observed by FESEM, improved the fiber–matrix
adhesion, and hence the performance properties. Artificial neuron network (ANN) was used for prediction of the wear behavior
of composites. 相似文献
8.
Hayrettin Ahlatci Tolga Koer Ercan Candan Huseyin imenolu 《Tribology International》2006,39(3):213-220
In this study, dry sliding metal–metal and metal–abrasive wear behaviours of the aluminium matrix hybrid composites produced by pressure infiltration technique were investigated. These composites were reinforced with 37 vol% Al2O3 and 25 vol% SiC particles and contained up to 8 wt% Mg in their matrixes. While matrix hardness and compression strength increased, amount of porosity and impact toughness decreased with increasing Mg content of the matrix. Metal–metal and metal–abrasive wear tests revealed that wear resistance of the composites increased with increasing Mg addition. On the other hand, abrasive resistance decreased with increasing test temperature, especially above 200 °C. 相似文献
9.
A series of composites of polyetheretherketone (PEEK) containing short carbon fibre (CF) in the range of 0–30% (w/w) was developed. Their wear behaviour in low amplitude oscillating wear (LAOW) mode was studied under various operating parameters such as load and temperature. The LAOW mode was studied in ball‐on‐plate configuration against steel (100 Cr 6) at ambient temperature and at 100°C. In this mode, the coefficient of friction (µ), specific wear rate (Ko) and limiting loading pressure‐sliding speed (PV) values were investigated. It was observed that with increase in %CF, the wear performance and utility of PEEK (limiting PV value) improved significantly. Thirty percent CF was best performing composite in all aspects. The µ, however, was hardly influenced with the inclusion of CF or variation in operating parameters. The same composites were also evaluated in abrasive wear mode to study the influence of severe operating conditions on wear and friction performance. In this wear mode, the CF‐filled composites showed poorer wear resistance than did neat PEEK. The specific wear rate was correlated with strength properties and it was observed that these composites closely followed the predictions of the Ratner–Lancaster plot. Scanning electron microscopy was used to examine the microstructural features of worn surfaces. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
10.
A composite with continuous carbon fibers (CF) (80% by vol.) and high performance thermoplastic polyetherimide (PEI) matrix was developed and evaluated for various mechanical properties as a function of fiber orientation angle (0°, 30°, 45°, 60° and 90°). It was observed that Young's modulus, Poisson's ratio, toughness and % strain decreased with the increase of fiber orientation angle with respect to loading direction. In-plane shear modulus was highest for fibers with 45°. Overall, unidirectional (UD) CF reinforcement enhanced all strength properties of PEI significantly. Composites with fibers in 0° (parallel to loading direction) proved best in almost all the properties. Tribological evaluation in abrasive wear mode under different loads and fiber orientations indicated that coefficient of friction (μ) and specific wear rate (K0) decreased with load, in general. Comparatively low specific wear rate (K0), (in the order of 0.7 1×10?9 m3/Nm) was observed for 0° fiber orientation, while fibers in 90° showed almost three times higher wear rate. Overall fiber reinforcement in 0° orientations proved beneficial from both strength and tribological performance point of view. SEM proved useful to correlate wear rate with surface topography. 相似文献
11.
Oxidation treatment with concentrated HNO3 was employed to the carbon fabric (CF) for various time intervals (30–180 min) to observe the effect of treatment on two simultaneous processes involved viz. improvement in its adhesion with the matrix and reduction of fiber strength which in turn is responsible for change in the performance properties of composites. Seven composites with untreated and acid treated CF were developed based on the polyetherimide (PEI) matrix and evaluated for adhesive wear properties under various loads (200–600 N) against mild steel disc. 90 min treated CF composite indicated the best tribological properties and showed 30% reduction in specific wear rate (K0) and 23% in coefficient of friction (μ) respectively at 600 N load. Treatment beyond this time proved detrimental for improvement in properties. Field emission scanning electron microscopy (FE-SEM) showed increase in roughness with treatment time, while atomic force microscopy (AFM) studies indicated substantial increase in roughness value. Scanning electron microscopy (SEM) of worn surfaces supported the wear mechanisms and improvement in adhesion between fiber and matrix. 相似文献
12.
In fretting fatigue process the wear of contact surfaces near contact edges occur in accordance with the reciprocal micro-slippages on these contact surfaces. These fretting wear change the contact pressure near the contact edges. To estimate the fretting fatigue strength and life it is indispensable to analyze the accurate contact pressure distributions near the contact edges in each fretting fatigue process.So, in this paper we present the estimation methods of fretting wear process and fretting fatigue life using this wear process. Firstly the fretting-wear process was estimated using contact pressure and relative slippage as follows:
W=K×P×S,