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This paper aims to explore the damage mechanism of a lubricating film on the worn surface of solid self-lubricating composites under different loads.

By comparing the actual stress with the strength, it is possible to determine the approximate wear state of the lubricating film. To prove the validity of the mathematical model that can predict the initiation of micro cracks or even the failure of the lubricating film, M50-5 Wt.% Ag self-lubricating composites (MA) was prepared. Tribological tests of the composites against Si₃N₄ ceramic balls were conducted at room temperature from 2 to 8 N. The electron probe microanalysis images of the lubricating film verify the wear state of the lubricating film.

The study found that the back edge of the contact area is the most vulnerable to destruction. The tensile stress and the equivalent shear stress have a positive correlation with load and friction coefficient. When the load is 4 N, an intact lubricating film covers the worn surface because the tensile stress and the equivalent shear stress are below the tensile strength and the shear strength, respectively; under other working conditions, the lubricating film is destroyed.

This paper has certain theoretical guidance for the study of tribological properties of solid self-lubricating composites. Moreover, this mathematical model is appropriate to be applied for the other composites.

This paper aims to study the micro-structure evolution of friction layers to optimize the friction and wear behaviors of TiAl-based material. It further enlarges the scope of using TiAl alloys and increase in the service life of TiAl alloy-made mechanical components, especially under some extreme conditions.

To study the structure evolution of friction layers, the HT-1000 tribometer is used to study the friction and wear properties of as-prepared samples. With the assistance of field emission scanning electron microscopy and an electron probe micro-analyzer, the stratified structures in cross-sections and a surface morphology of the wear scars are well characterized. A ST400 surface profiler helps in better understanding of the three-dimensional texture profiles of wear scars. X-ray diffractometer (XRD) is also used to analyze phases in the as-prepared samples.

An analysis method on the micro-structure evolution can provide better views to understand the influence of friction layers on the tribological behavior, at different wear stages. It finds that the micro-structure evolution of friction layers has an immediate effect on the friction coefficients and wear rates of TiAl-based material. It also proves to be a useful tool for evaluating the behaviors in friction and wear of TiAl-based material.

The findings of this paper provide better assistance to explore the effect of friction layers on the friction and wear behaviors of TiAl-based materials. The results help in deep understanding of the micro-structure evolution of friction layers. It also increases the service life of TiAl-based mechanical components.

The main aim of this paper was to study the self-lubricating behavior and failure mechanism of silver-rich solid film for in-depth analyzing of the friction and wear property of TiAl-10 wt. per cent Ag self-lubricating composite.

The friction and wear property of TiAl-10 wt. per cent Ag self-lubricating composite sliding against Si3N4 ball was tested under the testing conditions of ball-on-disk wear system. Field emission scanning electron microscopy and electron probe microanalyzer were used to analyze the surface morphology of silver-rich solid film. The main element contents were tested by energy dispersive spectroscopy. Silver phase on wear scar could be well identified using X-ray photo-electron spectroscopy. The theory calculation of shearing stress on wear scar was executed to discuss the local failure mechanism of silver-rich solid film. The lubricating role of silver was also discussed to analyze the anti-friction and anti-wear behavior of silver-rich solid film.

The friction coefficients and wear rates of TASC gradually reduced at 0-65 min, and approached to small values (0.31 in friction coefficient and 3.10×104 mm3N-1m-1 in wear rate) at 65-75 min. The excellent friction and wear behavior of TASC was mainly attributed to the lubricating property of silver-rich film at 65-75 min. At 12→20 N, surface shearing stress increased up to 146.31 MPa, and exceeded more than the shearing strength (125 MPa) of silver-rich film, which caused the propagating of fatigue crack and the destroying of silver-rich film, leading to high friction and severe wear.

It is important that the self-lubricating behavior and local failure of solid film is explored for further understanding the friction and wear property of TiAl alloys.

This study aims to investigate how the public formed their need for information in the early stage of the COVID-19 outbreak. Exploring the formation of information needs can reveal why the public's information needs differ and provide insights on targeted information service during health crises at an essential level.

The data were collected through semi-structured interviews with 46 participants and analyzed using the grounded theory approach. Concepts, sub-categories and categories were developed, and a model was built to examine how the public formed the need for information about the pandemic.

The authors found that participants were stimulated by information asymmetry, severity of the pandemic and regulations to control the pandemic, which triggered their perceptions of information credibility, threat and social approval. After the participants perceived that there was a threat, it activated their basic needs and they actively formed the need for information based on cognitive activities. Moreover, information delivered by different senders resulted in a passive need for information. Participants' individual traits also influenced their perceptions after being stimulated.

Long-term follow-up research is needed to help researchers identify more detailed perspectives and do comparative studies. Besides, this study conducted interviews through WeChat voice calls and telephone calls, and might be limited compared with face-to-face interviews.

The findings of this study provide theoretical contributions to the information needs research and practical implications for information services and public health management.

There is little systematic research on how the public formed information needs in the early stage of the COVID-19 outbreak.

Unconventional machining processes, particularly ultrasonic vibration cutting (UVC), can overcome such technical bottlenecks. However, the precise mechanism through which UVC affects the in-service functional performance of advanced aerospace materials remains obscure. This limits their industrial application and requires a deeper understanding.

The surface integrity and in-service functional performance of advanced aerospace materials are important guarantees for safety and stability in the aerospace industry. For advanced aerospace materials, which are difficult-to-machine, conventional machining processes cannot meet the requirements of high in-service functional performance owing to rapid tool wear, low processing efficiency and high cutting forces and temperatures in the cutting area during machining.

To address this literature gap, this study is focused on the quantitative evaluation of the in-service functional performance (fatigue performance, wear resistance and corrosion resistance) of advanced aerospace materials. First, the characteristics and usage background of advanced aerospace materials are elaborated in detail. Second, the improved effect of UVC on in-service functional performance is summarized. We have also explored the unique advantages of UVC during the processing of advanced aerospace materials. Finally, in response to some of the limitations of UVC, future development directions are proposed, including improvements in ultrasound systems, upgrades in ultrasound processing objects and theoretical breakthroughs in in-service functional performance.

This study provides insights into the optimization of machining processes to improve the in-service functional performance of advanced aviation materials, particularly the use of UVC and its unique process advantages.

The effects of the thermo-mechanical treatment on the properties and microstructure of the Al–Cu–Mg–Ag alloy were investigated.

A short-duration preprecipitation process is designed prior to predeformation aging. The novel predeformation aging (solution treatment + holding at 185 °C for 15 min+ rolling deformation + aging at 185 °C, also named T8) was performed on a heat-resistant Al–Cu–Mg–Ag alloy.

The purpose of this study indicate that a short-duration heat treatment before predeformation is beneficial to the precipitation of O during the aging process. The precursors of O during this process might pin the dislocation and cause the grains to orient along some specific direction, which might be advantageous to the precipitation of O while disadvantageous to that of θ′. This novel thermal-mechanical process could result in an increase in the quantity and decrease in the size of the precipitation of O, which leads to a remarkable strength effect. The potential increases while the current density decreases with an increase in the deformation amount, which implies a smaller intergranular corrosion rate. The fine deformed structure leads to an opposite behavior in the exfoliation corrosion test compared with that for intergranular corrosion.

The intergranular corrosion resistance of the Al–Cu–Mg–Ag alloy is enhanced, whereas the exfoliation corrosion resistance is reduced by novel predeformation aging.

The purpose of this paper is to review the evolution of policies and practices of open innovation (OI) in China under globalization.

This is a review paper. It combines historical archives and case study approaches, covering policies and practices at both the macro‐ and micro‐levels.

It is found that Chinese firms have in practice employed a variety of OI models since the reforms of science and technology systems in the mid‐1980s. Policies introduced by the Chinese Government with respect to inbound and outbound OI, as well as policies encouraging OI networks, have encouraged Chinese firms to adopt various OI modes and practices. Some critical institutional challenges still need urgent attention and effective efforts to reinforce them.

This paper aims to fill the gap in the literature by providing the first systematic review of the evolution of the policies and practices of OI in China, and exploring the implications for latecomer firms in building indigenous innovation capability. As far as the authors are aware, this is one of the first systematic review studies on OI policies and practices with a focus on emerging economies.

This paper aims to study the corrosion inhibition behavior of imidazopyridine and its three derivatives on brass.

The authors performed weight loss experiments, electrochemical experiments including the polarization curve and electrochemical impedance spectrum, corrosion morphology observation using scanning electron microscope (SEM) and atomic force microscope (AFM) and surface composition analysis via X-ray photoelectron spectroscopy (XPS) to analyze the corrosion inhibition behavior of imidazopyridine and its three derivatives on brass by using quantum chemical calculation (Gaussian 09), molecular dynamics simulation (M-S) and Langmuir adsorption isotherm.

According to the results, imidazole-pyridine and its derivatives were found to be modest or moderately mixed corrosion inhibitors; moreover, they were spontaneously adsorbed on the metal surface in a single-layer, mixed adsorption mode.

The corrosion inhibition properties of pyrazolo-[1,2-a]pyridine and its derivatives on brass in sulfuric acid solution were analyzed through weight loss and electrochemical experiments. Moreover, SEM and AFM were simultaneously used to observe the corrosion appearance. Furthermore, XPS was used to analyze the surface. Then, Gaussian 09 and M-S were combined along with the Langmuir adsorption isotherm to investigate the corrosion inhibition mechanism of imidazole-[1,2-a]pyridine and its derivatives.