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Purpose: This paper aims to study different morphology Cu6Sn5 effect on Babbitt alloy tribological properties. Design/methodology/approach: Different morphology Cu6Sn5 of Babbitt was conducted by different cooling modes. Bare Babbitt was marked by Babbitt-0, Babbitt modified by first cooling mode (marked by Babbitt-1) and Babbitt modified by second cooling mode (marked by Babbitt-2). The microstructure and microhardness of specimens were tested. Then, tribological properties of Babbitt-0, Babbitt-1 and Babbitt-2 were performed by reciprocating mode under lubricated condition. Findings: The results showed that shape Cu6Sn5 of Babbitt was changed from mixed needle and star-like shape to short rod-like or granular shape. The microhardness of Babbitt-1 was highest than that of Babbitt-0 and Babbitt-2. Compared with Babbitt-0 and Babbitt-2, tribological properties of Babbitt-1 were better under lubricated condition due to short rod-like and sparse distribution of Cu6Sn5. Moreover, the simulation result of strain and stress of Babbitt-1 was lowest than that of Babbitt-0 and Babbitt-2. Originality/value: Different morphology (shape and distributed) of Cu6Sn5 was obtained by different cooling modes. Modulated different forms of Cu6Sn5 around SnSb was beneficial to improve Babbitt alloy tribological properties. [ABSTRACT FROM AUTHOR]

Carbon fabric reinforced phenolic-based composites (CF/PF composites) often act a potential alternative to traditional materials which currently used in machine elements such as self-lubricating bearing, high-performance gears, and movable sealed. In the present study, the CNTs@MoS2 hybrids were synthesized by hydrothermal method, which were used as additives for their optimal wear resistance and lubricating properties in order to enhance the tribological properties of CF/PF composites. We found that the CF/PF composites with varying contents of CNTs@MoS2 hybrids showed improved self-lubricating properties under different sliding conditions, and the friction coefficient decreased as the content of additives increased. Nevertheless, the doping of 1 wt% hybrids decreased the wear resistance of CF/PF composites due to the occurrence of severe abrasive wear caused by peeling off of matrix in relatively large volume. However, with the contents of hybrids increased to 2 wt% and 4 wt%, the CF/PF composites exhibited improved wear resistance. The mechanism of wear resistance could be attributed to the excellent mechanical properties of CNTs and strong interfacial bonding force between hybrids and matrix as well as the formation of MoS2 transfer film on the surface of counterpart. [ABSTRACT FROM AUTHOR]

In this paper, an unbalanced Jeffcott rotor supported by the roller bearings is modelled, and the dynamic differential equations are obtained by the Lagrange’s equations. The fourth order Runge–Kutta method is employed to simulate this system in two cases. Simulation results show the combined effect of the coupled lateral and torsional vibrations and the variable compliance vibration of the rotor. In the case of that only a large and constant radial force is applied, the sum and difference between variable compliance and rotational frequency components of the torsional vibrations of the disk are induced because of the roller bearings’ rotation. And when they are near to the natural frequency of the torsional vibration, the resonance peaks appear. In the case of that a large and constant radial force and a harmonic torque are simultaneously applied, the two components, the sum and difference between rotational frequency and the frequency of the external torque, of the lateral vibrations of the disk are induced. When the frequency of the external harmonic torque approximatively equal to a special value, the two frequency band lines, variable compliance and the sum of rotational frequency and the frequency of external torque, intersect near the natural frequency of the lateral vibration, and the vibration may aggravate. [ABSTRACT FROM AUTHOR]