The Research On Synthesis And Application Of Ternary Layered Carbide Cr₂AlC

Mn+iAXn compounds,with unique layer structure and excellent mechanical properties,have got the favor of researchers.Cr2AlC,one of the representative of Mn+1AXn,has many properties like high thermal conductivity,high electric conductivity and good anti thermal shock properties,and also owns high intensity,high sheer modulus,high Young modulus,good corrosion resistance,high-temperature oxide resistance and all that.Thus,Cr2AlC has a wide application prospect.In this paper,the synthesis technology of Cr2AlC powder has been studied at 950-1050? in normal atmosphere by using aluminum powder,chromium powder and graphite power as raw materials.Firstly,the orthogonal test method has been designed based on literature reports and primary experiment results,the process parameters,such as the synthesis temperature,the ratio of raw materials.Results show that the increase of Al,reduce the quality of raw materials and cosolvent,enhance the synthesis temperature,would improve the production rate of Cr2AlC.Secondly,On the basis of preliminary experiment designed orthogonal experiment,the synthesis temperature,ratio of raw materials,ratio of raw materials and cosolvent,Cr:Al:C and other process parameters are optimized,the optimal level combination for:ratio of raw material and cosolvent is 1:1,the synthesis temperature is 1050 ?,Cr:Al:C is 2:1.2:1,the holding time is 3h;To validate the optimal level combination experiment,the results from orthogonal experiment nine times in the test results are good,and based on the result amplification tests have been carried out,can get 50?100 g Cr2AlC powders one-time,the particle size in the range of 5?20 microns.Threedly,the compositions of molten salt are researched,and the specific measurements to reduce the dissipation of molten salt are put forward.Adding BaCl2 in KC1 + NaCl can effectively inhibit latent solvent volatilization,and using BaCl2 KC1 + NaCl synthesize Cr2AlC powders of yield was the highest.Finally,the effects of the circumstance,including vacuum,carbon thermic aerosphere and aerosphere,have been studied on the synthesis procedure,and it is found that the oxidization of raw materials occurred in the heating-up process.So a new synthesis method,synthesis powder in salt-bath,is presented,that is,the raw material block is directly pressed into the salt bath to syntheses Cr2AlC powder,in order to avoid using special circumstances such as vacum,carbon thermic aerosphere,and this greatly reduce the synthesis cost of Cr2AlC powder.In addition,the copper base composite reinforced with Cr2AlC powder has also been prepared,and the properties of Cu/Cr2AlC composite are investigated simply,which will lay the foundation for the application of Mn+1AXn compounds.