Search

This study aims to investigate a novel high‐efficient antioxidant for synthetic ester oils. An ester‐bridged antioxidant, phloroglucinol tris (3‐[3,5‐di‐tert‐butyl‐4‐hydroxyphenyl]) propionate (PTP), was successfully synthesised in high yield under relatively mild reaction conditions. Thermal stability and oxidation resistance of diisooctyl adipate (DOA) ester oil were determined and compared to the typical commercial phenol antioxidants, including its tribological properties. The results indicate that the prepared PTP antioxidant exhibits considerably higher thermal stability than commercial antioxidants, and it also improves the oxidation resistance of the synthetic ester oil more effectively. Moreover, the addition of PTP antioxidant enhanced the wear protection of DOA ester oil without deteriorating its lubricating performance. The ester‐bridged antioxidant can be used as a multifunctional additive, which not only exerts excellent thermal stability and oxidation resistance, but can also act as an efficient anti‐wear agent in synthetic ester oils. [ABSTRACT FROM AUTHOR]

Polymer blends have been widely used as tribological materials for replacements of traditional metals and ceramics. Polymer blends consist of the reinforced phase, the matrix phase and interfaces between reinforced and matrix phase. Although the interface structure of polymer blends is usually small in size, it is one of the key factors for deciding the physical and tribological properties of polymer blends. Thus, this review highlights the most recent trends in the field of influences of interface structure on tribological properties of engineering polymer blends. Emphasis is given to the improvement methods of interfacial compatibility of polymer blends and the behavior variation of interface structure during friction process. [ABSTRACT FROM AUTHOR]

[Display omitted] • Low power density laser treatment causes oxidation and amorphization of UHMWPE. • High power density laser treatment results in carbonization of UHMWPE. • Laser-induced carbonization can improve the tribological properties of UHMWPE. The influencing mechanism of laser treatment on the tribological behavior of ultrahigh molecular weight polyethylene (UHMWPE) in a seawater environment was studied. The relation between the surface chemical composition and morphology of UHMWPE under different laser processing parameters and tribological properties in seawater environment was obtained. Oxidation and amorphization occurred when UHMWPE was laser-treated at relatively low-power densities (1.92 × 105 and 3.94 × 105 W/cm2), causing the slightly increase in wear rate of UHMWPE. Carbonization occurred after relatively high-power densities laser treatment (6.01 × 105, 8.12 × 105 and 1.00 × 106 W/cm2), causing significantly increase in wear resistance and decrease in friction coefficient. The laser-induced carbonization products were mainly composed of amorphous and graphitic carbon, which served as a solid lubricant during friction, thereby significantly improving the tribological properties of UHMWPE in the seawater environment. A method of laser-induced carbonization was proposed to improve the tribological properties of polymer materials in a seawater environment. Controlling the degrees of surface oxidation and carbonization of UHMWPE effectively regulated its tribological properties in seawater environments. [ABSTRACT FROM AUTHOR]

Polyimide/ultrahigh molecular weight polyethylene (PI/UHMWPE) blends with different mass ratio were produced. A ratio-image method was adopted by plotting the ratio of Raman peak intensity of a typical band of PI with that of UHMWPE as a function of position, Raman Mapping images with a relatively high accuracy and enhanced visualization were obtained. Two-phase distribution morphologies of the blends were studied using Raman Mapping. Effects of blend phase morphology and phase distribution on the tribological properties of blend composites were investigated. The results indicated that both the phase structures and their distribution are obviously different for the PI/UHMWPE blends with different mass ratios, which significantly influence the tribological properties of the blends. PI phase disperses in an island form in the UHMWPE matrix phase when the mass ratio of PI/UHMWPE is relatively small (10/90). The scattered PI dispersed phase effectively reduces the friction coefficient of the blend and improves the wear resistance. For the PI/UHMWPE blend composite with the mass ratio of 30/70, layered PI phase forms and distributes in the UHMWPE matrix phase, improving bearing capacity and wear resistance of the blends. Large continuous area structure and phase separation occurs in the blend when the mass ratio of PI/UHMWPE increases to 50/50, resulting in a significant reduction in the wear resistance of the blend composite. Image 1 • A ratio-image method was adopted by plotting the ratio of Raman peak intensity of a typical band of PI with that of UHMWPE as a function of position. • Different phase morphologies and their distribution are formed for the PI/UHMWPE blends with different mass ratios. • PI/UHMWPE blend with island or layered morphology of PI improves the tribological properties of UHMWPE. [ABSTRACT FROM AUTHOR]

In this work, the causes of failure of electroplating silver coatings on aero-engine nuts were explored. And the microhardness of low temperature pulsed DC magnetron sputtering silver coatings was increased by 25%, and the bonding force was increased by about 1.2 times. At high temperature, the friction coefficients of magnetron sputtering silver coatings was about 20% lower than that of electroplating silver coatings, and the wear volume was about 90% lower than that of it at maximum. The wear mechanism of magnetron sputtering silver coatings was mainly abrasive wear, while that of electroplating silver coatings was mainly adhesive wear. Besides, the results of molecular dynamics showed that silver coatings would move and aggregate in layers during the friction. • Adhesive wear and abrasive wear cause failure of silver coatings on aero-engine nuts. • Low hardness, poor bonding, and thickness uniformity are defect of silver coatings. • Magnetron sputtering silver coatings better perform at high temperature. • Silver coatings transfers and aggregates during friction. [ABSTRACT FROM AUTHOR]