Synthesis And Properties Of Ti₃C₂T_x/Al Composites

MXene is a new two-dimensional layered material,which is obtained by selective etching of A atomic layer in MAX phases(where M represents a transition metal element,A represents a ?,? main group element,and X represents nitrogen or carbon).The MXene material prepared from it as a precursor has only been discovered in recent years.MXene has a graphene-like structure and a eombination of mechanieal properties,electrical properties and magnetic properites.Up to now,most of the investigations have focused on functional performance of Ti3C2Tx prepared by acid etching of Ti3AlC2 precursor powders.Aluminiun matrix composites are the most studied and widely used as light metal materials.In recent years,one-dimensional carbon nanotubes(CNT)and two-dimensional graphene(GR)reinforced Al matrix composites with improved properties have attracted much attension.However,the easy agglomeration of CNT and GR in the Al matrix and their poor wettability with Al causes weak interfaces in the composites.It is still a challenge to overcome the above problems.Ti3C2Tx has a large number of-OH,-O and-F functional groups on the surfaces,which promotes the wettability of Ti3C2Tx and Al.Hence,it is desirable to make new Ti3C2Tx/Al composites with stronger interfacial strength.To prepare Ti3C2Tx/Al composites,we first studied the chemical stability of Ti3C2Tx and Al.Differential scanning calorimetry analysis,X-ray diffraction analysis,scanning electron microscopy and transmission electron microscopy were used to characterize the reaction,phase composition and microstructure.The results showed that Ti3C2Tx react with Al to form Al3Ti at above 700?,but they are stable at temperatures below 700?.To obtain dense Ti3C2Tx/Al composites,hot pressing,pressurless sintering followed by hot extruding,and SPS sintering followed by hot extruding were used.In addition,the effect of Ti3C2Tx eontent on the properties of Ti3C2Tx/Al composites was investigated.It was found that sintering followed by hot extruding can make the dense composites with enhanced tensile strength and hardness.The hardness and tensile strength of the composites also increase with increasing Ti3C2Tx content.As the content of Ti3C2Tx was up to 3 wt.%,the hardness and tensile strength of the composites were 0.3 GPa and 98 MPa,respectively,corresponding to 92%and 50%increase,respectively,as compared with 0.59 GPa and 148 MPa for pure Al.The wear tests for the pure Al and Ti3b2Tx/Al composites showed that the latter has a friction coefficient of 0.15,lower than 0.45 for pure Al,indicating that Ti3C2Tx lubricates the surfaces and improves the friction and wear propertries of composites.