Study On Tribological Properties Of Epoxy Composites Modified By Ti₃C₂ MXene

Epoxy resin is a kind of important engineering polymer materials.Because of good mechanical properties,outstanding bonding properties and the easy curingcharacteristic,epoxy resin is widely used as grinding wheel bonds,engineering plastics,electronic and electrical materials.And it is widely used in aerospace,mechanical manufacturing,military equipment and other fields.However,with the development of industry and the improvement of manufacturing level,the working environment of the equipment is tougherand the performance requirements of mechanical devices are increasing.Due to the poor thermal performance and poor friction performance,traditional epoxy resin and its composite materials cannot meet the requirements of high performance equipment,machine parts and machining.In this work,epoxy resin was modified by a new two-dimensional material,Ti₃C₂MXene,to improve its microhardness,tribological properties and thermal properties.The mechanism of performance improvement is discussed,which provides experimental basesanda theoretical reference for the application and processing of epoxy resin.Firstly,Ti₃C₂ MXene was prepared by etching the purchased MAX phase（Ti₃AlC₂）powder with hydrofluoric acid solution.The preparation process andexfoliation process of Ti₃C₂ MXene were investigated.The prepared Ti₃C₂ MXene was characterized.The results show that Ti₃C₂ MXene possesses excellent tribological properties and thermal properties.Secondly,the Ti₃C₂/Epoxy composites were prepared by a solution blending method.The hardness,thermal conductivity,thermal expansion properties,glass transition temperature and thermal stability of the composites are gradually improved with an increase in the amount of Ti₃C₂ MXene fillers.When the filler content of Ti₃C₂/Epoxy composite is 1wt%,the thermal conductivity,the glass transition temperatureand the hardness are141.3%,13.6%and29.4%higher than those of neat epoxy,respectively.And the thermal expansion coefficient is decreased by 12.1%at 40°C.Underdry sliding,when the load is 5 N and the frequency is 2Hz,the friction coefficient value of epoxy composite with only 0.5 wt%Ti₃C₂ MXene fillers,is reduced by 69.8%compared with that of neat epoxy.The wear rate of epoxy composite with only 0.25 wt%Ti₃C₂ MXene fillers,is reduced by 66.4%compared with that of neat epoxy.However,when the load is increased to 15 N,the large load breaks the bonding state between the filler and the matrix.The friction coefficient of Ti₃C₂/Epoxy composite with only0.5 wt%Ti₃C₂ MXene suddenly rises at 30 min,and the wear volume is larger than that of neat epoxy.When the frequency is 4 Hz,the friction coefficient and the wear rateof each material decrease significantly.Under water lubrication,when the load is 5 N and the frequency is 2 Hz,the friction coefficient of neat epoxy and Ti₃C₂/epoxy composite with0.5wt%Ti₃C₂ MXene fillers is decreased.Due to the high fluidity of water,the wear rate is increased.Finally,a three-dimensional network structure of few-layer of Ti₃C₂ MXene nanosheets was constructed by a freeze-drying methodand Epoxy-Ti₃C₂ 3DNS composites was prepared.Compared with neat epoxy resin,the thermal conductivity and hardness of Epoxy-Ti₃C₂3DNS 3.0 composite with 3.0 g Ti₃C₂ MXene increased by 48.9%and 74.9%,respectively,and the thermal expansion coefficient decreased by 9.5%at 40°C.Underdry sliding,when the load is 5 N and the frequency is 2 Hz,the coefficient of friction（0.170）of Epoxy-Ti₃C₂ 3DNS1.0 composite with 1.0 g Ti₃C₂ MXene was reduced by 76.3%.The wear rate(9.942×10^-5mm³/mN)of Epoxy-Ti₃C₂ 3DNS 3.0 composite was reduced by 67.3%.The friction coefficients of Epoxy-Ti₃C₂ 3DNS 1.0 composite decrease to some extent with the increase of load,and the wear volume values increase.With the increase of frequency,the friction coefficient and wear volume of Epoxy-Ti₃C₂ 3DNS 1.0 composite increase and the wear rate decreases gradually.The tribological properties of Epoxy-Ti₃C₂ 3DNS 1.0 composite under water lubrication are different.When the load is 5 N and the frequency is 2 Hz,the friction coefficient and is increased.