Search

Solid lubricants are added to polymers to upgrade their tribological properties, especially in cases where adhesive and abrasive friction are valid. However, there are not enough studies on the effects of solid lubricants on particle erosion. This study investigated the effects on solid particle erosion behavior of three different well known solid lubricants (molybdenum disulfide, polytetrafluoroethylene, and graphite). These solid lubricants were added at three different ratios (5, 10, and 15 wt.%) to the two different type (rigid and toughened) epoxy resins. Garnet abrasive particles (180–400 μm) were blasted to the sample surface under 1.5 bar for 15 s to conduct solid particle erosion tests. The erosive wear mechanisms of neat and solid lubricant‐reinforced epoxy resins were investigated in relation to the epoxy type, solid lubricant type, and solid lubricant reinforcement ratio. Statistical analysis was performed according to response surface methodology to support the experimental results, and ANOVA tables were obtained. The wear and deformations that occurred on the surface after solid particle erosion were examined using a noncontact optical profilometer system and scanning electron microscopy, and a significant relationship was detected between the deformation on the surface and particle erosion. Analysis results showed that the factor causing the greatest erosion rate change was the epoxy resin type. Finally, it has been observed that all solid lubricants reduce the erosive wear resistance, and this resistance decreases as the weight ratio increases. Highlights: Investigations were conducted into the erosion behavior of two types of epoxy resins: rigid and toughened. The toughened epoxy resin exhibited greater resistance to erosion. Although it has the same type of content, on average, rigid epoxy worn 2–4 times more than toughened epoxy.The effect of adding polytetrafluoroethylene tended to increase the erosion rate of both rigid and toughened epoxy resin less than that of other solid lubricants.Graphite particles increased the erosion rate of toughened epoxy by 1.5–3 times and that of rigid epoxy by 2–3 times, depending on the value of the reinforcement ratio.MoS2 increased the erosion rate of toughened epoxy by 1.5–3 times and that of rigid epoxy by 2–3 times.Using a noncontact optical profilometer (for investigating surface topography), it was proven that there is a significant relationship between the erosion rate and roughness characteristics. Wear mechanisms were identified by SEM analysis. [ABSTRACT FROM AUTHOR] more...

As it is known, Polytetrafluoroethylene (PTFE) is one of the most preferred polymeric materials for tribological applications. This study investigates the performance of PTFE and its composites under different tribological conditions. The effects of short glass fiber (GF), carbon particle (CP) and bronze particle (BP) reinforcement agents and their hybrid filling with molybdenum disulfide (MoS2) on sliding, erosive and abrasive wear were examined. Sliding tests were carried out with a ball‐on‐disc test apparatus, erosive wear tests were carried out with solid particle erosion and abrasive wear tests were carried out with a scratch test. It has been found that reinforcement agents improve sliding and abrasive wear resistance but worsen the erosion resistance. The hardness and contact angle of the samples were associated with their wear performances. Topographic and morphological analyzes of worn surfaces were performed using optical profilometer and scanning electron microscopy (SEM), respectively, and wear mechanisms were discussed. Highlights: Filling materials (glass fiber, carbon particle and bronze particle) increase the adhesion and abrasion resistance of PTFE, while decreasing its erosion resistance.The effect of hybrid addition of MoS2 solid lubricant on wear performances depends on the type of filler.There is a correlation between surface properties (hardness and contact angle) and wear performances.Optical profilometer and scanning electron microscopy were used to examine wear mechanisms. [ABSTRACT FROM AUTHOR] more...

Epoxy resins inherently have low resistance to scratching. To increase the scratch resistance of epoxy resins, reinforcing solid lubricants into the resin is an option. For this purpose, in this study, polytetrafluoroethylene (PTFE) and graphite were reinforced in two different epoxy resins (rigid and toughened) at different reinforcement ratios (5, 10, and 15 wt%). The effects of solid lubricant reinforcement on the scratch behavior of rigid and toughened epoxy resins were examined both experimentally and statistically. Scratch tests were performed throughout a distance of 10 mm using a test apparatus under a load of 15 N and a scratch speed of 30 mm/min. Following the scratch tests, the COF (Coefficient of Friction) values, scratch hardness, scratch width, and depth of all samples were determined and compared to neat epoxy for each resin. In general, it has been determined that solid lubricant reinforcement at higher reinforcement ratios has a positive effect on the COF value (15 wt%). In the case of 15 wt% graphite reinforced rigid and toughened epoxy, a decrease of 15.90% and 17.77%, respectively, was obtained in the COF value compared to the neat epoxy. After the scratch tests, statistical analysis was performed according to RSM to support the experimental results, and ANOVA tables were obtained. Highlights: Epoxy adhesives exhibit low scratch resistance.Examining the impact of PTFE and graphite reinforcement on scratch behavior.Two types of epoxy and varied reinforcement ratios (5, 10, and 15 wt%) were studied.Solid lubricant reinforcement to epoxy positively affected scratch behavior. [ABSTRACT FROM AUTHOR] more...

This study investigated the tribological performance of hybrid composites composed of scrap carbon fiber (CF), glass fabric (GF), and polyamide 6.6 (PA6.6) through an innovative approach for reusing scrap CFs in high‐value composite structures. The experimental setup included CF/GF/PA6.6 hybrid composite laminates with varying CF contents and surface‐modified GFs, as well as PA6.6 sheets and GF/PA6.6 composite laminates. Solid particle erosion and scratch tests were conducted to assess the influence of scrap CF hybridization and GF surface modification on the tribological properties of the composites. The results demonstrated that neat PA6.6 sheets exhibited the lowest erosion rate, while the incorporation of CF and GF reinforcements had a detrimental effect on erosion resistance. The highest erosion rate was observed within the impact angle range of 15°–30° for pure PA6.6 sheets, whereas for composite laminates, it occurred within the range of 30°–45°. In contrast, CFs positively affected scratch hardness despite their negative impact on erosion resistance. Additionally, the silane treatment of GFs, which enhanced interfacial strength, improved the erosion resistance and scratch hardness of GF/PA6.6 composite laminates without CF. Profilometer‐based topographic analysis revealed a correlation between the average surface roughness of the eroded surfaces and the weight loss resulting from solid particle erosion. [ABSTRACT FROM AUTHOR] more...

In this study, various heat treatments (annealings) were applied to carbon fiber reinforced polyetheretherketone (CF/PEEK) samples at four different temperatures (185, 225, 265, and 305°C) along two different holding times (30 and 270 min). The effects of changing matrix morphology, degree of crystallinity, and fiber‐matrix interface properties on thermo‐mechanical properties were investigated by differential scanning calorimetry (DSC) and dynamic mechanical analysis analyzes. Also, annealed CF/PEEK samples were tested to determine solid particle erosion characteristics. It was observed that the matrix crystallinity, fiber/matrix interface properties, and tribological properties of the CF/PEEK composites changed significantly with the thermal history. There was an increase in the degree of crystallinity with the increase in annealing temperature. It was observed that the degree of crystallinity increased up to about 27% and the damping factor decreased up to about 45%. As a result of the solid particle erosion tests performed under normal impact conditions, it was determined that the formation of the transcrystalline layer formed by heat treatment adversely affected the solid particle erosion resistance of the CF/PEEK. Erosion resistance of the heat‐treated samples (having higher fiber/matrix interface) was approximately 50% lower compared to the quenched sample. While the erosion rate for quenched samples is 14.5 × 10−5 g/g, this rate rises to 26.1 × 10−5 g/g for annealed samples. In addition, surface topography was examined by means of an optical profilometry, and surface morphology was examined by means of scanning electron microscopy. These examinations confirmed the experimental results. [ABSTRACT FROM AUTHOR] more...

Modern-day engineering applications favor polymers and polymer composites on the grounds of their high specific properties. They can offer many different advantages compared to metals; such as high strength-to-weight ratio, ease of production, but their erosion resistance is weaker. In polymer composites, material loss occurs because of high-speed and repeated exposure to erosive particles, therefore service performance and life of the parts are adversely affected. Due to this, it is crucial to predict the particle erosion that may occur in engineering applications and to know the erosive wear behavior of the materials well. Polytetrafluoroethylene and its composites are widely used in tribological applications because of their load-carrying capacity, self-lubricating, and low-density properties, but there is inadequate literature on particle erosion behavior. In this study, particle erosion behaviors of polytetrafluoroethylene, its randomly oriented short glass fiber, and carbon particle and bronze particle-reinforced composites were investigated under different test conditions. Two different types of erosive particles (garnet and alumina) were used to present the effect of erodent type on particle erosion behavior. After particle erosion tests, surface topographies were examined by an optical profilometer, and surface morphologies were examined by scanning electron microscopy. It has been found that the type of reinforcement and the type of erodent significantly affects the particle erosion behavior of polytetrafluoroethylene and its composites. [ABSTRACT FROM AUTHOR] more...

Polymer materials with high specific strength properties are widely used in engineering applications. Poly (methyl methacrylate) (PMMA) is a rigid and brittle thermoplastic with a high glass transition temperature. It is used in many engineering applications due to its low density, lightweight, high transparency, chemical resistance, and high toughness properties. Intense research efforts have been carried out in recent years regarding the scratching behavior of polymers. The scratch test is performed by moving a hard abrasive indenter across the surface of relatively soft material and is used to determine the mechanical resistance of the surfaces of materials. Scratches on the surfaces of amorphous polymeric materials such as PMMA cause optical and mechanical performance loss. For this reason, it is important to determine the scratching behavior of materials under different operating conditions. Within the scope of the study, the scratching behavior and multi-pass scratch behavior of PMMA were investigated. Experimental studies were carried out with Rockwell and Vickers abrasive indenters at different scratch force and velocity values. Scratch and wear marks were examined by means of an optical microscope, optical profilometer and Scanning Electron Microscope (SEM), and scratch hardness, volumes removed, surface topographies and surface morphologies are presented. It has been observed that these results vary remarkably depending on the type of abrasive indenter, scratch force and velocity. [ABSTRACT FROM AUTHOR] more...