Purpose
The content of pore-foaming agent directly affects pore characteristics and oil-absorption properties of polyimide (PI) porous materials, which further influence the tribological performance of PI pore material. This research paper aims to discuss these issues.
Design/methodology/approach
Thermal vacuum molding technology was adopted to prepare PI porous material with different structures by changing the content of the pore-forming agent to control pore size and porosity of the PI material. PI oil-bearing materials were obtained by vacuum oil immersion. The tribological experiments of PI oil-bearing materials were conducted on the CETR friction and wear testing machine.
Findings
The study results showed that PI porous material with a specific structure can be obtained by controlling the content of a pore-forming agent. In a certain range, with the increase in the content of the pore-forming agent, the average pore size and porosity increased, also the oil content increased, which means that the friction coefficient and wear rate decreased to a very large extent, and antifriction and wear resistant properties of the PI porous materials greatly improved. When the content of the pore-forming agent exceeds 8 per cent, the wear rate and friction coefficient of the PI porous materials began to increase.
Originality/value
Because the complexity of the tribological system consists of lubricating oil, porous material and friction pair, the physical understanding of the mechanism of this process remains limited. Therefore, the present research was undertaken to identify the phenomena involved, which will provide practical guidance for the tribological application in the field of bearing parts.
Sixteen groups of GF/Nano‐Al2O3/PA66 composite samples were prepared by injection molding process and orthogonal experimental design method. The water absorption, hardness, compressive strength, and tribological properties under water conditions were measured. The wear surface morphology and material transfer from mate pair were analyzed by scanning electron microscopy (SEM) and energy spectroscopy (EDS). The results show that the minimum friction coefficient of G25A1 ratio is 0.064, which is 54.3% and 72.2% lower than the two common used sucker rod centralizer materials, respectively; the wear rate of G20A7 is the minimum 7.46 × 10−5 mm3 (N m)−1, 63.6% and 19.9% lower than the two commonly used sucker rod centralizer materials, respectively; the water absorption, hardness and compression strength properties of 16 groups were improved; PA66 matrix composites with the best ratio of 20% GF and 7% Al2O3 were selected in this paper; the wear mechanism of the composite is fatigue wear and a little adhesive wear at moderate additive content, and it is easy to form a transfer film on the mating surface.
Purpose
The purpose of this study is to improve the dispersion of nanoserpentine modified with OA, KH550 and KH550/oleic acid in lubricating oil. The main aims are to analyze the influence of the dispersion and stability of nanoserpentine modified by different modifiers on the friction properties of lubricating oil.
Design/methodology/approach
The nanoserpentine particles obtained by ball-milling were modified by silane coupling agent KH550, OA and KH550/OA, respectively. The dispersity and stability of nanoserpentine in base lubricating oil were characterized by the absorbance value method, centrifuge precipitation rate method and static observation method. The MMU-5G screen display friction and wear tester was used to evaluate the tribological properties of C45E4/C45E4 friction pairs in corresponding lubricating oils. The surface morphology of the friction pairs was observed by scanning electron microscopy and energy dispersive spectroscopy.
Findings
The results showed that the dispersity and stability of nanoserpentine particles in lubricating oil were best modified by OA, followed by the KH550/OA and finally, the KH550. Nanoserpentine particles modified with oleic acid showed optimum tribological properties as lubricant additives.
Originality/value
This study can improve the dispersion stability of nanoserpentine particles in lubricating oil, increasing the antiwear and antifriction performance of lubricating oil, which has great significance in economic and military aspects.
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