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In recent years, the sudden rise of high entropy alloys (HEAs) has become a hot research topic in the field of metal materials. The high entropy alloy is located in the central region of phase diagram, which has broad alloy composition space and possible formation of microstructure. The synergistic regulation of composition and preparation process can obtain richer structure. Unconventional chemical structure is expected to break through the performance limit of traditional anti-wear and lubricating alloys. In this work, the classification of wear-resistant HEAs was discussed. The effects of the addition of chemically active metals, soft metals and refractory metals on the wear resistance and lubrication properties of HEAs were analyzed. The effects of non-metallic elements and ceramic phases on the tribological properties of HEAs matrix composites were summarized. The effects of heat treatment and surface engineering technology on the surface microstructure and tribological behavior of HEAs were reviewed. The design method of HEAs with anti-wear lubrication under severe working conditions was discussed. The future research and application of HEAs in the field of friction and wear were prospected. High entropy alloys have great potential to solve the bottleneck problems of traditional alloys, such as to realize stable lubrication and anti-wear under extreme working conditions and to ensure anti-wear under specific functions.

Porous flower-like SnO2/CdSnO3 microstructures self-assembled by uniform nanosheets were synthesized using a hydrothermal process followed by calcination, and the sensing performance was measured when a gas sensor, based on such microstructures, was exposed to various volatile organic compound (VOC) gases. The response value was found to reach as high as 100.1 when the SnO2/CdSnO3 sensor was used to detect 100 ppm formaldehyde gas, much larger than those of other tested VOC gases, indicating the high gas sensitivity possessed by this sensor especially in the detection of formaldehyde gas. Meanwhile, the response/recovery process was fast with the response time and recovery time of only 13 and 21 s, respectively. The excellent gas sensing performance derive from the advantages of SnO2/CdSnO3, such as abundant n–n heterojunctions built at the interface, high available specific surface area, abundant porosity, large pore size, and rich reactive oxygen species, as well as joint effects arising from SnO2 and CdSnO3, suggesting that such porous flower-like SnO2/CdSnO3 microstructures composed of nanosheets have a high potential for developing gas sensors. [ABSTRACT FROM AUTHOR]

Three-dimension solid model of helical gear limited slip differential is built by using CATIA,and then the virtual prototype model is established through importing the 3D solid model into ADAMS/View. In the virtual environment,based on the kinematics dynamics simulation and analysis with two different typical work conditions,including straight-line driving on good pavement and double tire-road friction coefficients,the torque curve,the force and angular velocity curves of helical gear of limited slip differential are acquired.By comparing with theoretical calculations values,the correctness of model and the effectiveness of simulation method are verified. The study results provide the basis for the dynamic optimization and fatigue life prediction of the helical gear limited slip differential.

This project is the construction project of the academic report comprehensive building of the Central Youth League School. The main function of the project is the academic report room, including an 800-person lecture hall, a 300-person multi-function lecture hall, a 500-person multi-function lecture hall, an exhibition hall, etc., and three underground floors. There are three floors above the ground, and one floor is partially high. There are 12.8, 13.8, 15.7, 18.2, 18.6, 20.8, 27.8 meters in the sub-regions of the roof structure elevation. This article introduces the structural system, the judgment of structural out-of-limit situations, prestress design, steel truss design, suspension steel structure design, cantilevered large-span concrete beams, etc., through a variety of structural calculation and analysis methods, and find out structural weaknesses, and adopt Corresponding seismic strengthening measures, the calculation results show that the structure has good seismic performance and can meet the requirements of the code.