B. Suresha

Friction and Wear Characteristics of Carbon-epoxy and Glass-epoxy Woven Roving Fiber Composites

Polymer materials when reinforced with high modulus fibers yield higher strength, higher stiffness, better toughness, and good dimensional stability. Fiber reinforcements are effective in reducing wear in adhesive situations in addition to increasing the strength and stiffness. The adhesive conditions are generally encountered in automotive and aerospace applications. In such applications, the types of reinforcement material used are important from the point of improved performance under different tribo situations. In this particular investigation, carbon-epoxy (C-E) composite is compared with that of glass-epoxy (G-E) composites for tribological properties using a pin-on-disc set up. The tests are conducted by subjecting C-E samples sliding against a hard steel disc (62 HRC) under different sliding and loading conditions. This article highlights the friction and wear behavior of these composites run for a constant sliding distance, where in the C-E composites show lower friction and lower slide wear loss compared to G-E composites irrespective of the load or speed employed. Some of the wear data are supported by the scanning electron microscope (SEM) images.

Mechanical and Three-body Abrasive Wear Behavior of Carbon-Epoxy Composite With and Without Graphite Filler

Fiber and particulate reinforced polymeric composites are known to possess high strength and attractive wear resistance in dry sliding conditions. Though the reinforcement and/filler type are known to control the properties, less is known about their tribo performance especially with graphite as filler material. How these composites perform in abrasive wear situations needs a proper understanding. Hence, the present investigation reports on the mechanical and three-body abrasive wear behavior of carbon fabric reinforced epoxy (C-E) and silane treated graphite filled C-E (Gr-C-E) composites. The mechanical properties were evaluated using Universal testing machine. In three-body wear tests, quartz particles of size 150-200 μm were used as dry and loose abrasives. Three-body abrasive wear tests were conducted using rubber wheel abrasion tester under different loads/abrading distances. The results showed that the wear volume increased with increasing abrading distance and the specific wear rate decreased with abrading distance/load and depends on filler loading. However, the presence of silane treated graphite filler in C-E showed a promising trend. Further, the abrasive wear volume of composites has been correlated with mechanical properties such as hardness, tensile strength and percentage elongation. The worn surface features, when examined through scanning electron microscopy, showed more number of broken carbon fibers in C-E compared to graphite filled C-E composites.

Investigation of the Friction and Wear Behavior of Glass-Epoxy Composite With and Without Graphite Filler

Polymeric composites have steadily gained importance in recent years for industrial applications. The increase in use calls for a better understanding of their behavior under different working environments. Friction and wear are considered two important parameters that govern tribological behavior. In this study, the friction and wear characteristics of E-glass-epoxy (G-E) and graphite filler of three different levels in G-E composites were experimentally investigated using a pin-on-disc set-up at varied loads and sliding velocities. From this investigation, it was found that a 7.5 wt% graphite filled G-E composite system showed least coefficient of friction and highest wear resistance compared to the plain G-E composite system, irrespective of the load/speed adopted. Besides conventional weighing, determination of coefficient of friction and examination of worn surface features were undertaken using a scanning electron microscope (SEM) for interpretation of wear behavior.

Dry Sliding Wear Behaviour of Carbon Fabric-Reinforced Epoxy Composite with and without Silicon Carbide

Carbon fabric-reinforced epoxy composites with and without silicon carbide filler were prepared by hand lay-up technique followed by compression moulding. These composites were tested on a pin-on-disc wear tester. The dry sliding wear test conditions include different applied load and sliding velocity. In this study, friction and dry sliding wear behaviour of silicon carbide (SiC)-filled carbon fabric-reinforced epoxy (C-E) composites were investigated. The weight fraction of SiC filler was varied (0, 5 and 10 wt%) so as to obtain composite samples of three different compositions. Sliding wear experiments were conducted using a pin-on-disc wear tester. The tests were conducted at a fixed sliding distance by varying the applied load and sliding velocity. The results show that for increased load and sliding velocity, higher wear loss was recorded. Excellent wear characteristics were obtained with C-E containing SiC as filler. Especially, 10 wt% of SiC in C-E gave a low wear rate. Moreover, the results reveal that 5 and 10 wt% of SiC in C-E showed 21 and 35 percentage of increase, respectively, in the wear resistance as compared with unfilled C-E composite. The wear resistance of the C-E and SiC-filled C-E composites was found to be related to the stability of the transfer film on the counterface. Moreover, incorporation of SiC in C-E showed improved mechanical properties. The results have been supplemented with scanning electron micrographs to help understand the possible wear mechanisms.

Three-body Abrasive Wear Behavior of Filled Epoxy Composite Systems:

Particulate filled epoxy composites have been studied for the three-body abrasive wear behavior using the rubber wheel abrasion test (RWAT) apparatus. The epoxy composites were fabricated with 0—20 wt% of the boron carbide in steps of 5wt%. In the present investigation, angular silica sand particles of size in the range 200—250 μm were used as dry and loose abrasives. The wear volume and wear rate were determined as a function of abrading distance. The filler additions have shown significant influence on three-body abrasive wear behavior at different loads. It was observed that inclusion of boron carbide filler in particulate form into epoxy matrix showed improved abrasion resistance. Scanning electron microscopy was used to study the worn surface features to understand the mechanisms involved in the removal of material.

Mechanical and abrasive wear behavior of carbon fabric reinforced epoxy composite with and without fly ash cenospheres

Carbon fabric reinforced epoxy and carbon fabric reinforced epoxy containing different weight fraction of silane-treated fly ash cenospheres filled composites were cast, sectioned, and subjected to three-body abrasive wear tests for evaluating the abrasive wear behavior. Mechanical characterization was done and a comparison was made between the different samples. Abrasive wear tests were performed on a rubber wheel abrasion tester under different loads, abrading distances using quartz and silica sand as abrasives. The results showed that both unfilled carbon fabric reinforced epoxy and fly ash cenospheres filled carbon fabric reinforced epoxy composites exhibit differing magnitudes of wear volume loss, it being highest for unfilled carbon fabric reinforced epoxy composite. The data trends point to the fact that the wear volume and specific wear rate decreases with increasing fly ash cenospheres loading in carbon fabric reinforced epoxy composites. It was found that silane-treated fly ash cenospheres could effectively reduce the wear rate especially under silica sand as abrasives. To explain these differences, the worn surfaces were examined using scanning electron microscope and the features thus observed were correlated with the selected mechanical properties.

Friction and Dry Slide Wear of Short Glass Fiber Reinforced Thermoplastic Polyurethane Composites

The friction and dry slide wear behavior of short glass fiber (SGF) reinforced thermoplastic polyurethane (TPU) composites was studied in this article. The SGFs were mixed by 20, 30, and 40 wt% in TPU matrix. Composites were processed by the injection molding technique. The un-lubricated pin—on-disk wear tests were conducted by varying the load and sliding velocity. The results reveal that the slide wear loss increases with increasing load/sliding velocity. The coefficient of friction increases with increase in sliding velocity. The coefficient of friction and wear rate of the composites decreased with increase in SGF content. Further, 40% SGF reinforced TPU composite exhibited lower friction coefficient and wear rate than 20 and 30% SGF reinforced TPU composites. The worn surface features have been explained using scanning electron microscopy.

Influence of micro and nanofillers on mechanical properties of pultruded unidirectional glass fiber reinforced epoxy composite systems

This paper reports, fabrication and characterization of unidirectional glass fiber reinforced epoxy composite filled with nano-size alumina, silica and micron-size alumina trihydrate fillers using pultrusion technique. Tensile, flexural and impact strengths were determined to evaluate the effectiveness of fillers on the mechanical properties. Results show that the micro and nanofillers act as secondary reinforcement. The tensile, flexural and impact strengths of 10 wt% (combined alumina, silica and alumina trihydrate)-filled glass fiber reinforced epoxy composite improved by 9, 20 and 28%, respectively, as compared to the unfilled and alumina/silica-filled glass fiber reinforced epoxy composites. The enhanced performance of micro and nanofillers-filled glass fiber reinforced epoxy composites is due to better adhesion and good dispersion of particulates in the epoxy matrix providing increased surface area for strong interfacial interaction and better load transfer. The improved mechanical properties indicate that the unidirectional glass fiber reinforced epoxy with combined micro- and nanofillers-filled composite is a good candidate for structural application.

Physico-mechanical behaviour of thermoplastic co-polyester elastomer/polytetrafluroethylene composite with short fibers and microfillers

Short fibers and particulate fillers are known to enhance the mechanical properties of the polymers. The type of fiber and filler morphology, size, loading, and dispersion homogeneity influence extensively the composite’s performance. In the present study, various amounts of short fiber (glass and carbon) and micro-scale particles (silicon carbide, alumina and molybdenum disulphide) were systematically introduced into thermoplastic copolyester elastomer/polytetrafluroethylene (TCE/PTFE) composite for reinforcement purpose. The influence of these fibers and fillers on the tensile, flexural, and impact properties was investigated. All composite samples were fabricated using twin-screw extruder followed by injection molding. The incorporation of short glass fiber (SGF) yielded an effective improvement in mechanical properties of TCE/PTFE composite at a fiber loading of 20 wt.%. Choosing the 20 wt.% SGF-reinforced TCE/PTFE composite, short carbon fiber and microparticles were further added in order to achieve additional improvement in the mechanical properties. In fact, synergistic effects were in the form of a further increase in hardness, tensile modulus, flexural and impact strength. Various reasons to explain these effects in terms of reinforcing mechanisms were discussed. Also, dispersion of the fiber and fillers were studied using scanning electron microscopy.

Dynamic mechanical analysis and three-body wear of carbon–epoxy composite filled with SiC particles

The changes that can occur in particulate filled and carbon fabric reinforced epoxy polymer matrix (carbon–epoxy) composites with aging (temperature change) can affect its application, performance, and life time. Fiber and particulate-reinforced composites are known to posses the high strength and attractive wear resistance in dry siding conditions. Though reinforcement and/filler type are known to control the properties, less is known about their abrasive wear performance especially with SiC particulates. How these composites performed in abrasive wear situation needs a proper understanding. Hence in this investigation, reports on dynamic mechanical and three-body abrasive wear behavior of carbon–epoxy and silane-treated SiC particulates filled carbon-epoxy composites. The dynamic mechanical analysis test were conducted using DMA Q800 instrument and abrasive wear tests were conducted using the Rubber wheel abrasive wear tester. From the dynamic mechanical analysis result, it was found that the glass transition temperature (Tg) of 10% SiC-filled carbon–epoxy composite was changed up to maximum 75°C, compared with that of unfilled carbon–epoxy composite. This change in Tg was believed to be due to the interface modification in SiC-filled carbon–epoxy composite. Three-body abrasive wear test results showed that the wear volume loss increased with increasing abrading distance and specific wear rate decreased with abrading distance/load and depends on SiC filler loading. However, the presence of silane-treated SiC in carbon–epoxy showed a promising trend. The worn surface features, when examined through scanning electron microscopy, showed differing trends for unfilled and SiC-filled carbon–epoxy composites.