Research On Diffusion Expansion And Mechanical Properties Of Sodium Based On Meso-structures In Cathode Carbon Blocks Of Aluminum Electrolysis

Aluminum electrolytic cathode carbon block with first failure can lead to aluminum electrolytic cell shortened lifespan.Sodium and electrolyte seepage erosion into cathode lining,cathode carbon block lining caused by inflation,then failure damage is the most core factor of cathode carbon block first failure.Cathode carbon block for multiphase composite material,the spatial distribution of various phase composition and the interaction between material in,will make carbon blocks show different macro performance.The cathode carbon block from the mesoscopic structure research will lead to internal damage,revealing the mesoscopic structure of sodium osmotic swelling and the influence of the mechanical properties of carbon blocks.The paper under the national natural science fund project(No.51264011)funding,in view of the present simulation study of cathode carbon block will see mostly as uniformity of material,the lack of mesoscopic structure of cathode carbon block under study,from the perspective of cathode carbon block mesoscopic,mesoscopic heterogeneity model is established,the mesoscopic structure is studied by using finite element software,the simulation study,the research content is as follows:Provides an aluminium electrolytic cathode carbon block detection technology.Through microscopic CT technology of cathode carbon block for digital image,calculate the each size and area of the carbon aggregate particles,got the proportion of each component of the cathode carbon block,pore content is 0.031,the asphalt content is 0.183,the carbon content of aggregate is 0.756,impurity content at 0.029,on the analysis of the carbon aggregate composition on a deep level,it is concluded that the proportion of the carbon aggregate particles in different area,the powder of area ratio was 37.42%,the small particles is 55.51%,the middle particle is 4.31%,larger particles was 2.74%.Based on mesoscopic structure are studied aluminum electrolytic sodium diffusion process of cathode carbon block.Mesoscopic structure of cathode carbon block,as carbon aggregate and asphalt two-phase composites,the finite element software ANSYS,establish a cathode carbon block mesoscopic two-dimensional random aggregate model,to simulate the diffusion process of sodium in the homogenization of carbon blocks,respectively investigates the carbon composition and content of aggregate size and morphology of the influence of sodium diffusion process.Results show that the carbon aggregate relative to the asphalt sodium diffusion of carbon block has more effect,oval aggregate,gradation 3-6 mm carbon aggregate,sodium content of 60% carbon aggregate diffusion rate of the slowest.Circular aggregate,gradation 3-15 mm carbon aggregate,sodium content of 80% carbon aggregate diffusion rate is the fastest.Based on mesoscopic structure are studied sodium aluminum electrolytic cathode carbon block expansion stress.At the mesoscopic level two-dimensional random aggregate model is set up,the sodium expansion stress model is solved using ANSYS software,the different shape,grading,content of sodium aggregate model expansion stress numerical simulation analysis.Results show that the circular smallest carbon aggregate expansion amount of sodium,sodium oval carbon aggregate expansion quantity biggest;Grading 3-15 mm carbon aggregate expansion quantity minimum,grading 3-6 mm biggest carbon aggregate sodium inflation;80% sodium expansion quantity minimum aggregate content,aggregate content of 60% sodium expansion amount is the largest.Based on mesoscopic structure aluminum electrolytic cathode carbon blocks are studied the mechanical behavior of damaged process.Of cathode carbon block from the Angle of mesoscopic structure,the establishment of two-dimensional,the on the model of random aggregate of cathode carbon block using ls-dyna finite element software to simulate the mechanical behavior under uniaxial compression,studies and analyzes the different shape,content,gradation of aggregate on the mechanical behavior of carbon blocks.Results show that the circular aggregate breakdown the slowest,oval aggregate fastest burst;Aggregate content 80% minimum burst degree,60% rupture most aggregate content,grading 3-6 mm aggregate damage extension is minimized,aggregate gradation 3-15 mm damage extension degree is the largest.