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As a fundamental component of aviation equipment, the gear has an essential effect on the service performance of the whole machine. Fine particle peening (FPP) technology is a good choice for the precision requirements of aviation gears. Therefore, a FPP model of aviation gears was constructed based on the discrete element‐finite element coupling method (DEM‐FEM) to simulate the evolution of surface roughness and residual compressive stress, and its results were verified by experiments. The effects of FPP intensity, coverage rate, and particle diameter on surface integrity were investigated. In addition, the importance degree of the intensity, coverage rate, and particle diameter of FPP on surface integrity was carried out by the random forest decision method. It demonstrates that the surface roughness Sa was mainly influenced by the FPP intensity and particle diameter. And the distribution state of the residual compressive stress was mainly affected by the particle diameter. Highlights: 1. The simulation model of FPP strengthening aviation gear based on DEM‐FEM was established. 2. The coefficient of restitution was taken into account in the damping force. 3. The importance degree of surface integrity was carried out by random forest method [ABSTRACT FROM AUTHOR]

Fine particle peening (FPP) technology offers an effective method to achieve outstanding surface integrity and fatigue performance in aviation gears. However, the lack of sufficient research on the correlation between process parameters, surface integrity parameters, and fatigue life undermines the full potential of FPP in strengthening aviation gears. Therefore, we have developed an elastic–plastic contact fatigue life model to predict the fatigue life of AISI 9310 gear steel after different strengthening processes. This model can consider surface integrity parameters such as surface micro‐topography, residual stress gradient, and hardness gradient. To validate the model, we conducted rolling contact fatigue tests and compared the results with the predictions from our model. The influence of process parameters on the rolling contact fatigue of AISI 9310 gear steel was further investigated. A process window for FPP was established, and an optimization method was proposed in order to provide guidance for selecting process parameters for FPP on high‐performance aviation gears. HIGHLIGHTS: 1. The rolling contact fatigue life of aviation gear after strengthening is predicted. 2. The simulation results are in good agreement with the rolling contact fatigue tests. 3. A process window for aviation gear steel after FPP is established. [ABSTRACT FROM AUTHOR]

Under extreme conditions such as high speed and heavy load, 18Cr2Ni4WA steel cannot meet the service requirements even after carburizing and quenching processes. In order to obtain better surface mechanical properties and tribological property, a hollow cathode ion source diffusion strengthening device was used to nitride the traditional carburizing and quenching samples. Unlike traditional ion carbonitriding technology, the low-temperature ion carbonitriding technology used in this article can increase the surface hardness of the material by 50% after 3 h of treatment, from the original 600 HV0.1 to 900 HV0.1, while the core hardness only decreases by less than 20%. The effect of post-ion carbonitriding treatment on mechanical properties and tribological properties of the carburized and quenched 18Cr2Ni4WA steel was investigated. Samples in different treatment are characterized using optical microscopy (OM), scanning electron microscopy (SEM), optimal SRV-4 high temperature tribotester, as well as Vickers hardness tester. Under two conditions of 6N light load and 60 N heavy load, compared with untreated samples, the wear rate of ion carbonitriding samples decreased by more than 99%, while the friction coefficient remained basically unchanged. Furthermore, the careful selection of ion nitrocarburizing and carburizing tempering temperatures in this study has been shown to significantly enhance surface hardness and wear resistance, while preserving the overall hardness of the carburized sample. The present study demonstrates the potential of ion carbonitriding technology as a viable post-treatment method for carburized gears. [ABSTRACT FROM AUTHOR]

Surface texture shape significantly influences the tribological and sealing properties of fluid mechanical face seals. Considering that it is a contradiction to simultaneously improve load capacity and reduce leakage, a numerical multi-objective optimization model is proposed herein to improve the load-carrying capacity while reducing the volume leakage rate via texture shape optimization. The mass-conserving cavitating boundary condition and the non-dominated sorting genetic algorithm II are employed for the optimization. The numerical results indicate that the optimal texture shape is spiral-like under the lowest volume leakage rate, which becomes an asymmetric flat-front chevron with increasing load-carrying capacity and volume leakage rate. The optimal shape outperforms four regular shapes (all obtained by multi-objective optimization) at different rotation speeds and sealing pressures. The cavitation within the optimal shape ensures zero leakage in fluid face seals. The comprehensive performance of the texture shape obtained by multi-objective optimization is superior to that obtained by single-objective optimization. [ABSTRACT FROM AUTHOR]

Titanium alloy has the advantages of high specific strength, good corrosion resistance, and biocompatibility and is widely used in marine equipment, biomedicine, aerospace, and other fields. However, the application of titanium alloy in special working conditions shows some shortcomings, such as low hardness and poor wear resistance, which seriously affect the long life and safe and reliable service of the structural parts. Tribocorrosion has been one of the research hotspots in the field of tribology in recent years, and it is one of the essential factors affecting the application of passivated metal in corrosive environments. In this work, the characteristics of the marine and human environments and their critical tribological problems are analyzed, and the research connotation of tribocorrosion of titanium alloy is expounded. The research status of surface protection technology for titanium alloy in marine and biological environments is reviewed, and the development direction and trends in surface engineering of titanium alloy are prospected. [ABSTRACT FROM AUTHOR]

Low-temperature plasma nitriding of austenitic stainless steel can ensure that its corrosion resistance does not deteriorate, improving surface hardness and wear performance. Nevertheless, it requires a longer processing time. The hollow cathode discharge effect helps increase the plasma density quickly while radiatively heating the workpiece. This work is based on the hollow cathode discharge effect to perform a rapid nitriding strengthening treatment on AISI 304 stainless steels. The experiments were conducted at three different temperatures (450, 475, and 500 °C) for 1 h in an ammonia atmosphere. The samples were characterized using various techniques, including SEM, AFM, XPS, XRD, and micro-hardness measurement. Potentiodynamic polarization and electrochemical impedance spectroscopy methods were employed to assess the electrochemical behavior of the different samples in a 3.5% NaCl solution. The finding suggests that rapid hollow cathode plasma nitriding can enhance the hardness, wear resistance, and corrosion properties of AISI 304 stainless steel. [ABSTRACT FROM AUTHOR]

In aerospace, aviation, nuclear power, and other high-tech fields, some essential moving parts must operate under high vacuum, high load, intense radiation, and other conditions. Under such extreme conditions, only solid lubricating materials can meet the lubrication requirements. Traditional material modification methods have problems such as high energy consumption, severe pollution, and narrow scope of application. Plasma modification technology can overcome these shortcomings. This paper focuses on several commonly used plasma preparation techniques for solid lubricating coatings, including plasma chemical heat treatment, physical vapor deposition, plasma immersion ion implantation and deposition, plasma spraying, and plasma electrolytic oxidation. Subsequently, the material systems of metal-based solid lubrication coatings are reviewed: soft metals, oxides, sulfides, nitrides, and carbon-based materials. Finally, found that the development of new solid lubricants, the improvement of existing preparation technology, and the development of new processes are the key development directions in the future. [ABSTRACT FROM AUTHOR]