Microstructures, mechanical properties, and grease-lubricated sliding wear behavior of Cu–15Ni–8Sn–0.8Nb alloy with high strength and toughness

Alloys used as bearings in aircraft landing gear are required to reduce friction and wear as well as improve the load‐carrying capability due to the increased aircraft weights.Cu–15Ni–8Sn–0.8Nb alloy is well known for possessing good mechanical and wear properties that satisfy such requirements.In this study,the microstructure,mechanical properties,and grease‐lubricated sliding wear behavior of Cu–15Ni–8Sn–0.8Nb alloy with 0.8 wt%Nb are investigated.The nanoscale NbNi3 and NbNi2Sn compounds can strengthen the alloy through the Orowan strengthening mechanism.A Stribeck‐like curve is plotted to illustrate the relationship among friction coefficient,normal load,and sliding velocity and to analyze the grease‐lubricated mechanism.The wear rate increases with normal load and decreases with sliding velocity,except at 2.58 m/s.A wear mechanism map has been developed to exhibit the dominant wear mechanisms under various friction conditions.When the normal load is 700 N and the sliding velocity is 2.58 m/s,a chemical reaction between the lubricating grease and friction pairs occurs,resulting in the failure of lubricating grease and an increase in wear.

A review on food oral tribology

Food entering the oral cavity undergoes a series of complex processing behaviors.It is subjected to compression and shearing by the teeth,tongue,and palate to reduce its size and mix with saliva until it is swallowed.The oral processing behaviors are thought to be closely related to both food and oral frictional properties.Much effort has been made in recent decades about food oral tribology to explore this complicated lubrication behavior.Understanding the lubrication mechanism of food in the mouth is important for improving the consumption experience and developing the novel food.This paper provides a new perspective on the effects of composition,texture,structure,and saliva-food component interactions on lubrication properties of different foods,the relationship between sensory perception and oral frictional behavior,and the mechanism and pattern of lubrication categorized by common food types.The roles of tribology in the improvement of food taste,the search for healthier ingredient substitutes,functional foods,and the development of green foods are analyzed.Conceptual and numerical prediction models among physical properties,sensory perception,and frictional behavior of food are discussed.Studies of simulating oral processing,such as the selection of friction pair materials,physical modification of contact surfaces,addition of saliva,different modes of motion,and contact forms are concluded and classified.The progress of commercial friction apparatus as well as customized friction devices applied to the food sector in recent years are described.The characteristics,performances,and applications of these tribological instruments are analyzed and compared.In addition,the results achieved by oral tribology in identifying adulterated foods and ensuring food safety are presented.Finally,some suggestions are put forward for the current challenges and future development of food oral tribology.