Tribological Experiments And Numerical Analysis Of Polymeric Borate Ester

Tribology includes three main components – friction,wear and lubrication.In most cases,our aim of study tribology is to obtain a lower friction coefficient as well as a lower wear rate,so that machines can work for a longer time and that the energy can be saved as much as possible.Some solid materials have very low friction coefficients even though without any lubrication.Most polymers have this kind of self-lubrication effect.Polytetrafluoroethylene(PTFE)is one of them,which is called “the king of plastics”.It has a better tribological property when it is added some other anti-wear materials such as glass fiber.However,most solid materials do not have low friction coefficient as polymers do.So some liquid lubricants are needed.Generally,lubricating oils are often added some additives in order to achieve better tribological properties.Nowadays,hundreds of thousands of researches all around the world are working on discovering better anti-wear and friction-reducing materials.So do us.Start with solid and liquid polymers,combining theory and practice,we have done the following works:1.We chemically synthesized several polymeric lubricant additives,including polyethylene glycol 200 borate ester(LPEG200B),polyethylene glycol 400 borate ester(LPEG400B),polyethylene glycol 600 borate ester(LPEG600B),and polypropylene glycol 200 borate ester(LPPG200B).After that,we respectively added them to rapeseed oil,and then tested their lubricating property.The result shows that with these borate ester additives,rapeseed oil's anti-wear and friction-reducing abilities are greatly improved.We also noticed that the higher molecular weight the better tribological properties additives have;2.A new mold for manufacturing PTFE-glass fiber samples was designed and made.Then the manufactured PTFE-glass fiber were tested by pin and disk wear tester.Results indicate that when properly added glass fiber,PTFE composites has lower friction coefficient and wear rate than pure PTFE does.It's also discovered that PTFEglass fiber can work in low friction coefficient and wear rate under sea water lubricating condition,due to its extraordinary corrosion resistance ability;3.Taking PTFE-glass fiber as the material of pins and disks,using the polymeradditives enhanced rapeseed oil as lubricant,pin and disk wear tests were conducted.An extremely low friction coefficient was detected.Unsurprisingly,the wear rate is also much lower comparing with the previous experiments in this thesis;4.By mechanical analysis,we built a mathematical model for pin and disk wear test and developed a numerical calculation program.Pin and disk's wear rate,wear volume can be automatically calculated by given parameters such as rotating speed,load,radius of pin,wear coefficients of pin and disk,and time duration.Pin and disk's wear rate and wear coefficients can also be deduced by experimental data such as wear volume,load,rotating speed and so on.5.To examine the validity of the theoretical model we built,five groups of pin and disk tribological experiments were conducted.The dimensional surface profiles were studied after PTFE-glass fiber pins and disks slided against each other.The results shows that the experimental data are highly consistent with the data calculated by our program,which proves our wear theory.