Synthesis And Properties Of Ceramic Mo₂TiAlC₂

Ternary carbide ceramic MAX phase has a unique valence bond type and crystal structure,M layer is almost closed,X almost filled the octahedral gap and M_n+1 X_n layer and A layer of alternating,Between M-X is the metallic bond and covalent bond,the M-X with A layer of van der Waals bond.Type and structure characteristics of the key causes the not only retain the characteristics of traditional ceramics,also with metal properties,namely the good electrical conductivity,easy workability,due to the M-X with A layer of Van Der Waals force is weak,easy to produce sliding,so greatly improved compared with the traditional ceramic fracture toughness,has a broad application prospect.First,use the Reflex module in the Material Studio software to simulate the Mo₂TiAlC₂standard X-ray diffraction peak.This paper uses the commercial molybdenum powder,titanium powder,aluminum powder and graphite powder,which is optimized by composition and temperature optimization,and finally the best preparation technology is determined.In accordance with the molar ratios of Mo:Ti:Al:C=2.2:0.8:1.1:1.8 the method of using in-situ hot-pressing sintering reaction,heats up with the heating rate of the 10 k/min to 1650?,30min insulation of 30 MPa pressure at the same time,The compact single phase can be prepared,up to 97.6%of theoretical density.Using X-ray diffraction to identify the type of object;The SEM with EDS has explored its grain size,grain morphology,microstructure and fracture mechanism.The mechanical,electrical and thermal properties are characterized by its young modulus and mass modulus,Vickers-hardness,fracture toughness,thermal conductivity and conductivity.It also explores the effect of Mo elements on the replacement of Ti position by systematically comparing the performance with the data and Ti₃AlC₂,which is calculated by the density functional theory.We hypothesized that it is possible that the Mo atomic radius?139 pm?is smaller than Ti atomic radius?147 pm?,and the electronegativity of Mo?2.16?is larger than the electronegativity of Ti atoms?1.54?,lead to the lattice parameters of bond length shorter,stronger bond between atoms.Mxene is the MAX phase of A atoms by other means such as HF acid etching of the formation of a class of two-dimensional graphene structure material,in electrical mechanical,photocatalytic and absorbing shielding should has a vast potential.It is easier to get the Mxene when MAX is in phase A for aluminum.This project explores the microstructure and valence structure of Mxene,which contains Mo,for the first time,by using a concentration of HF acid and other solutions to etch Mo₂TiAlC₂ as Mo₂Ti C₂Tx with double transitional elements.Raman spectra and XPS explored the microstructure and valence structure of Mxene with Mo.The results show that the Mo-Al bond vanished after the etching,and the Mo-F and Mo-O bonds are present,while the Ti atom changes relatively small.In energy storage,lithium ion battery and absorbing waves have potential application value.