| SiC heating dements have some disadvantages such as high resistance distribution,low working temperature,short service life etc.Those problems restrict the development of the SiC heating elements industry.So improving the performance and studying the relationship between performance and structure of the SiC heating elements are useful for enhancing the working temperature,service life and xploring new application field.In recent years the request of high performance SiC heating elements is increasing fast becauce of the development of industrial furnace high temperature technology and the special application.In this paper,(SiC heating elements whose density reached 2.58 g.cm-3was prepared with the commonly used extrusion moulding and recrystallization sintering process by using well packing SiC grain and suit water-soluble plasticizer.)And we discussed the influence of water-soluble plasticizer and packing grain on extrusion moulding process.We also analysed the connection between the products structure and performance.The result revealed that during the SiC heating element extrusion molding process,the extrusion pressure mainly exhausted by the friction among the grains or between grain and barrel.Suitable water-soluble plasticizer solution can have high maximum shear stress and good surface combination with the ceramic particle surface.With those character it can decrease the friction in the extrusion course.The performance of the water-soluble plasticizer can be predicted by some parameters such as viscosity,surface tension and contact angles with ceramic particle.Using the same plasticizer and molding pressure,we have studied the influence of grain grading grainon the density and other performances of the Silica Carbide Heating.The experiment result indicate that:1)In the extruding plastic process of Silica Carbide Heating Elements,particle packing is determined by replacement policy;the plasticizer and water volume shoud be regarded as part of the volume of fine grain;the optimum volume ratio of coarse grain and fine grain is 7:5for the density of Silica Carbide Heating Elements work section.2)Both coarse and fine grain's particle size have great influence on the density of the Silica Carbide Heating Elements work section.And when the 1.4mm diameter Coarse grain accounts for 40%,600um diameter Coarse grain accounts for 25%;100μm diameter middling grain accounts for 10%;5um diameter fine grain accounts for 25%,the density get its highest point that is 2.58 g/cm-3.In this paper we analysed the connection between the product performance and structure,the result shows that:1)The product with low porosity rate have better performance in electrical conductivity,anti-oxidation,service life.2)If the product have the similar porosity rate,the one which has better connectiong of grain get more excellent performance.3)The abnormal damage of the SiC heating element is always caused by overheating in some section,this phenomena is always connected with the connection of grain.
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