Tribological Properties Of Epoxy Composites Research Articles

Wear and friction of epoxy based nanocomposites with silica nanoparticles and wax-containing microcapsules

When subjected to wear by metal surfaces, epoxy normally exhibits rather high frictional coefficients (COF), causing high wear rate, exacerbated noise and frictional heat, thus limiting their service life. Liquid lubricants are known to reduce friction effectively, but they can be easily lost in operation. Therefore, encapsulating them is a proper solution to this issue. Herein, tribological properties of epoxy composites filled with wax-containing microcapsules (WMCs) and/or silica nanoparticles were investigated systematically. Results exhibited a tremendous decrease in the specific wear rates (Ws) and COF for the silica/WMC/epoxy ternary nanocomposites, specially three orders of magnitude reduction in Ws and a 10-fold reduction in COF were observed in specific test conditions. The wear mechanism was investigated based on worn surfaces and transfer films developed during wear tests. Furthermore, incorporating hybrid fillers negligibly deteriorates the mechanical properties of epoxy. Hence, the combination of rigid nanoparticles with WMCs is an appropriate choice when excellent tribological and mechanical properties are required.

Influence of the multi-walled carbon nanotube and short carbon fibre composition on tribological properties of epoxy composites

The present research work deals with the development of a novel polymer composite for brake pad applications. The composite that was used consists of epoxy resin, carbon fibre and carbon nanotubes in varying weight percentage. The tribological performance of three different samples was tested using a pin-on-disc under dry contact condition. The results indicated that the sample filled with short carbon fibres (SCF), and multi-walled carbon nanotube (MWCNT) had superior performance. Reduction in wear rate was observed due to synergism between SCF and MWCNT as compared to SCF only. Scanning electron microscopy was subsequently performed on all samples. The micrographs show changes in the structural formation after the incorporation of SCFs and MWCNT. This increased composite structural strength and explains why SCF and MWCNT’s hybrid-filled composite material has better tribological properties.

Tribological studies of epoxy composites with solid and liquid fillers

Epoxy-based composites are promising tribological coatings. The tribological properties of epoxy composites with filler materials such as graphene, graphite, and liquid lubricants (base-oil SN150 and perfluoropolyether) are studied. The composite coatings were applied on cylindrical steel surface and a steel ball was used as the counterface. Tests were conducted at 10N normal load and 0.63m/s linear sliding speed. Among all coatings, epoxy filled with graphene and SN150 lubricant provided the lowest coefficient of friction of 0.09 with wear cycles exceeding 200,000 and specific wear rate of 5.4×10−7mm3/N-m. Speed effects on friction were also evaluated.

Preparation of high thermal stability polysulfone microcapsules containing lubricant oil and its tribological properties of epoxy composites

Polysulfone (PSF) microcapsules containing lubricant oil have been successfully prepared using solvent evaporation method. The results show that lubricant oil was successfully encapsulated and the encapsulation capacity of about 56.0 wt.% was achieved. The uniform microcapsules have nearly spherical shape and quite smooth outer surface. The mean diameter is approximately 156 and 169 μm by using different dispersant solutions. The wall material is porous in structure with wall thickness of about 20 μm. The initial decomposition temperature of PSF is 480 °C. It is higher than traditional poly(urea-formaldehyde) (PUF) and poly(melamine-formaldehyde) (PMF) wall materials with 245 °C and 260 °C initial decomposition temperature, respectively. High thermal stability of PSF microcapsules can be considered as additives in high temperature resistant polymer materials. The frictional coefficient and wear rate of epoxy composites decreased significantly by incorporating microcapsules containing lubricant oil into epoxy. When the concentration of microcapsules was 25 wt.%, the frictional coefficient and specific wear rate were reduced by 2.3 and 18.3 times, respectively, as compared to the neat epoxy.

Mechanical and Tribological Properties of Graphene Modified Epoxy Composites

The effects of graphene content on the mechanical and tribological properties of epoxy composites were systematically investigated. The stiffness, hardness and elastic modulus of the composites increased with increased graphene content due to the higher hardness and elastic modulus of graphene sheets than those of epoxy matrix. The friction and wear of the composites measured using steel ball-on-disc microtribological test decreased with increased graphene content due to the solid lubricating effect of graphene sheets. It could be concluded that the mechanical and tribological properties of the epoxy composites could be significantly influenced by the incorporation of graphene sheets.

Effect of type, percentage and dispersion method of multi-walled carbon nanotubes on tribological properties of epoxy composites

In this work the wear behaviour of epoxy matrix composites with different types and percentages of multiwalled carbon nanotubes (MWCNTs) has been studied. Three different types (NC3100, NC3150 and NC3152) and percentages (0.1 and 0.5wt%) of MWCNTs were dispersed into an epoxy resin by a calendering process. The tribological properties of epoxy-MWCNTs nanocomposites were investigated using “pin-on disc” wear testing machine under different conditions (counterpart material, distances and sliding speeds test). Scanning electron microscopy and 3D optical profilometer were used to observe the worn surfaces of the samples. Compared with neat epoxy, the composites with MWCNTs showed a lower mass loss, friction coefficient and wear rate, and these parameters decreased with the increase of MWCNT percentage. Also, the results demonstrated that the epoxy composites with 0.5wt% of amino-MWCNT (NC3152) have the best tribological properties.

Short Carbon Fiber-Reinforced Epoxy Tribomaterials Self-Lubricated by Wax Containing Microcapsules

The effects of wax lubricant filled microcapsule content on the tribological properties of epoxy composites without or with 8 wt.% short carbon fibers (SCFs) were systematically investigated. The core percentage of the microcapsules used in this study was about 70 wt.%. The tribological results clearly showed that the friction and wear of the epoxy composites without or with SCFs tested against a 6 mm steel ball significantly decreased with increased microcapsule content from 2.5 to 10 wt.% as a result of the increased amount of released wax lubricant to lubricate rubbing surfaces. The epoxy composites with 8 wt.% SCFs exhibited the lower friction and wear than the ones without SCFs due to the combined lubricating effects of SCFs and released wax lubricant and the improved mechanical strength of the composites. It can be concluded that the higher microcapsule content gives rise to the lower friction and wear of the epoxy composites as the epoxy composites with 8 wt.% SCFs have the better tribological performance than the ones without SCFs.

Self-Lubricating and Wear Resistant Epoxy Composites Incorporated With Microencapsulated Wax

Self-lubricating and wear resistant epoxy composites were developed via incorporation of wax-containing microcapsules. The effects of microcapsule size and content and working parameters on the tribological properties of epoxy composites were systematically investigated. The incorporation of microcapsules dramatically decreased the friction and wear of the composites from those of the epoxy. The increased microcapsule content or the incorporation of larger microcapsules decreased the friction and wear of the epoxy composites due to the larger amount of released wax lubricant via the rupture of microcapsules during the wear test. The friction of the composites decreased with increased normal load as a result of the promoted wear of the composites and the increased release of the wax lubricant.

Mechanical and tribological properties of epoxy matrix composites modified with microencapsulated mixture of wax lubricant and multi-walled carbon nanotubes

Abstract The mechanical and tribological properties of epoxy composites modified with microencapsulated wax lubricant and multi-walled carbon nanotubes (MWCNTs) were investigated. The increased soft microcapsules embedded in the epoxy matrices were responsible for the reduced micro-hardness and Young’s modulus of the epoxy composites. It was found that the friction of the epoxy composites greatly decreased with increased microcapsule content due to combined lubricating effects of the both wax lubricant and MWCNTs. As a result, the wear of the epoxy composites apparently decreased with increased microcapsule content.