In this paper, friction and wear tests were carried out: 45# steel (carbon steel) was rubbed with aluminum bronze, aluminum bronze-based inlaid solid self-lubricating bearing (ISSLB) material, tin bronze, and tin bronze-based ISSLB material under different loads. The friction and wear properties (friction coefficient, wear amount and friction temperature) of the above four materials were studied. The friction and wear properties of the new self-lubricating bearing material and the traditional copper alloy under the same load were compared. The friction mechanism of each material in the friction process was discussed. The effect and mechanism of C-MoS2 composite solid lubricant on friction and wear properties were analyzed. Under the experimental loads of 100 to 500 N, the average friction coefficients of aluminum bronze-based ISSLB material were maintained in the range of 0.18~0.14, while the average friction coefficients of tin bronze-based ISSLB material were maintained between 0.26~0.20, which is much lower than those of copper alloy. The wear amounts of tin bronze-based ISSLB material were always in the range of 14.7~34.4 mg, which were much less than those of aluminum bronze-based ISSLB materials and copper alloy. The results show that the copper-based ISSLB materials possess excellent wear resistance, and the friction and wear properties of tin bronze-based ISSLB material are better than that of aluminum bronze-based ISSLB material. Therefore, if the copper-based ISSLB materials are applied to self-lubricating bearings, the friction and wear resistance of bearings will be greatly improved and the service life of bearings prolonged.

In order to address the shortcomings of the traditional bidirectional RRT* algorithm, such as its high degree of randomness, low search efficiency, and the many inflection points in the planned path, we institute improvements in the following directions. Firstly, to address the problem of the high degree of randomness in the process of random tree expansion, the expansion direction of the random tree growing at the starting point is constrained by the improved artificial potential field method; thus, the random tree grows towards the target point. Secondly, the random tree sampling point grown at the target point is biased to the random number sampling point grown at the starting point. Finally, the path planned by the improved bidirectional RRT* algorithm is optimized by extracting key points. Simulation experiments show that compared with the traditional A*, the traditional RRT, and the traditional bidirectional RRT*, the improved bidirectional RRT* algorithm has a shorter path length, higher path-planning efficiency, and fewer inflection points. The optimized path is segmented using the dynamic window method according to the key points. The path planned by the fusion algorithm in a complex environment is smoother and allows for excellent avoidance of temporary obstacles.

In this study, a multi-element microalloyed GCr15Si1MoNbV bainitic bearing steel was designed by adding trace amounts of Nb and V. The bainite/martensite/retained austenite/undissolved carbide multiphase bearing steel with a short heat-treated cycle and remarkable comprehensive mechanical properties was prepared via low-temperature austempering, which was compared with a traditional quenched and tempered martensitic microstructure. The results showed that the comprehensive mechanical properties of the low-temperature bainitic microstructure of the Nb/V microalloyed bearing steel were better than those of a traditional tempered martensitic microstructure. In addition, as the isothermal temperature increased, the impact toughness of experimental steel was significantly improved, and the hardness decreased slightly. The tensile strength was improved with the increase in isothermal time. As the isothermal temperature increased, the bainite content of the experimental steel rose, and the stability of the retained austenite enhanced due to more carbon atoms being partitioned into it. The research work in this paper made a preliminary exploration for the application of Nb/V microalloyed bainitic bearing steel in the bearing field and provided some basic data for reference.

In this paper, a new low-carbon alloy gear steel is designed via Si/Al alloying. The carburizing and austempering, at a temperature slightly higher than the martensitic transformation point (Ms) of the surface and much lower than the Ms of the core, for different times, were carried out on the newly designed gear steel. After heat treatment, a series of different microstructures (superfine bainitic ferrite + retained austenite, superfine bainitic ferrite + martensite + retained austenite, and martensite + retained austenite) were obtained on the surface, whilst the low-carbon lath martensitic microstructure was obtained in the core. The microstructure of the surface was examined using optical microscopy (OM), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The phase composition was analyzed using X-ray diffraction (XRD). The hardness and wear resistance of the surface as well as the hardness distribution of carburizing layer of the samples with different microstructures were studied. The results show that the Si/Al-rich gear steel, after carburizing and austempering at 200 °C for 8 h, not only has excellent mechanical properties but also has high wear resistance, which meets the technical requirements of heavy-duty gear steel. The research work in this paper can provide a data reference for the application of carburized steel with mixed microstructures of bainitic ferrite and martensite in the design of heavy-duty gear.