Current Issue : October-December Volume : 2024 Issue Number : 4 Articles : 5 Articles
In this study, the tribological properties of nanocomposites based on ultra-high molecular weight polyethylene (UHMWPE) lled with nano-CuO and 2-mercaptobenzothiazole (CuO/MBT) in mass ratios of 1:1 and 2:1 were investigated. In the supramolecular structure of UHMWPE nanocomposites, spherulites of several hundred micrometers in size are formed. The density of UHMWPE nanocomposites slightly increases relative to the pure polymer, reaching a maximum at 2 wt.% CuO/MBT in both ratios. The Shore D hardness and compressive stress of the UHMWPE nanocomposites showed an improvement of 5–6% and 23–35%, respectively. The wear resistance and coecient of friction of UHMWPE nanocomposites were tested using a pin-on-disk conguration under dry friction conditions on #45 steel and on P320 sandpaper. It was shown that the wear rate of UHMWPE nanocomposites lled with 2 wt.% CuO/MBT decreased by ~3.2 times compared to the pure polymer, and the coecient of friction remained at the level of the polymer matrix. Abrasive wear showed an improvement in UHMWPE nanocomposites lled with 1 wt.% CuO/MBT compared to the polymer matrix and other samples. The worn surfaces of the polymer composites after dry friction were examined by scanning electron microscopy and IR spectroscopy. The formation of secondary structures in the form of tribolms that protect the material from wear was demonstrated. Due to this, the wear mechanism of UHMWPE nanocomposites is transformed from adhesive to fatigue wear. The developed materials, due to improved mechanical and tribological properties, can be used as parts in friction units of machines and equipment....
To mitigate the environmental hazards aroused by fossil-based lubricants, the development of eco-friendly internal lubricants is imperative. Siloxane-based internal lubricants, widely applied as plasticizers in polymeric compounds, are a promising option. However, their impacts on the tribological properties of polymeric tribocomponents are still unclarified. Therefore, in the current study, a siloxane-based internal lubricant with the product name ‘EverGlide MB 1550 (EG)’ was dispersed into a polybutylene terephthalate (PBT)-based tribological composite to investigate whether the tribological properties of the composite can be optimized. A block-on-ring (BOR) test configuration was used for this purpose. It was found that the addition of EG to the composite significantly improved the tribological behavior; the improvement was particularly significant under lower load conditions (pv-product ≤ 2 MPa·m/s). Compared to the reference PBT composite, the addition of EG reduced the friction coefficient (COF) by about 30% and the specific wear rate by about 14%. An accompanying surface analytical investigation using photoelectron spectroscopy to elucidate the effective mechanisms at the molecular level showed the availability of tribologically effective and free EG after its addition to the composite in the relevant tribocontact....
This work investigates the tribological behavior of a machined S355JR structural steel in dry sliding conditions for the development of an innovative seismic dissipation system. Flat-ended pins and disks were made of the same structural steel to simulate the conformal contact of different device parts. Pins were machined by turning, while disks were milled and turned to obtain a nominal average surface Ra roughness ranging from 0.8 μm to 6.3 μm. The influence of the surface roughness on the coefficient of friction (COF), specific wear rate (SWR), and time to steady-state (TSS) was investigated. Tribological tests were conducted reciprocating motion in dry sliding conditions to simulate the operating conditions of the device, with 1 Hz and 2 Hz reciprocating frequencies and an applied normal load of 50 N. The Rsk and Rku roughness parameters helped to better understand the tribological response of milled and turned disks, having an influence on the TSS and SWR....
With the increasingly demanding engine conditions and the implementation of “double carbon” policies, the demand for high-quality lubricants that are cost-effective and environmentally friendly is increasing. Additives, especially high-performance friction modifiers, play an important role in boosting lubricant efficiency and fuel economy, so their developments are at the forefront of lubrication technologies. In this study, 1,3-dioleoamide-2-propyloleate (DOAPO), which incorporates polar amide, ester, and nonpolar alkyl chains, was synthesized from 1,3-diamino-2-propanol to give an eco-friendly organic friction modifier. Nuclear magnetic resonance (NMR), high-resolution mass spectrometry (HR-MS), Fourier-transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA) were used to characterize the structure and thermal stability of DOAPO. Meanwhile, the storage stability and tribological behaviors of DOAPO in synthetic base oil were studied and compared with a commercial oleamide. The results show that DOAPO has better thermal stability and better storage stability in synthetic base oil. Additionally, 0.5 wt.% of DOAPO could shorten the running-in period and reduce the average friction coefficient (ave. COF) and wear scar diameter (ave. WSD) by 8.2% and 16.2%, respectively. The worn surface analysis and theoretical calculation results show that the ester bond in DOAPO breaks preferentially during friction, which can reduce the interfacial shear force and easily react with metal surfaces to form iron oxide films, thus demonstrating a better friction-reducing and anti-wear performance....
One of the primary challenges in the automotive industry is the wear of engine components, such as the crankshaft and camshaft, which is the most pronounced during the engine’s startup phase, when the amount of lubricant fluid is at its lowest. This study aims to enhance the surface wear resistance of automotive crankshaft steel by applying a boriding thermochemical process. This process forms a hard surface layer on the steel, improving its mechanical properties and bolstering its wear resistance, especially under dry conditions. Boride layers were achieved using the powder-pack boriding process in a conventional furnace, with meticulous treatment times of 2, 4, and 6 h at a constant temperature of 950 °C. The nature of the layers was analyzed using X-ray diffraction, and their tribological behavior was evaluated using the pin-on-disk test. The growth of the layers was directly proportional to the treatment time and was estimated at 145 μm and 48 μm for the 6 and 2 h of treatment, respectively. The surface hardness increased from 320 HV for the non-treated steel to 2034 HV for the sample exposed to 950 °C for 6 h. The results indicate a significant reduction in the coefficient of friction from 0.43 for the nontreated steel to 0.12 for the samples exposed to 950 °C for 6 h, suggesting potential wear protection during the engine starting period....
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