The Studies On Influence Of Sintering Aids On The Structure And Properties Of SiC Wear-resistant Material

Silicon carbide ceramic has many excellent properties,such as high temperaturestrength,good abrasion resistance,high hardness,chemical corrosion resistance and thermalshock resistance,it has been widely used in precision bearings,heat exchanger components,at-omic nucleus reactor materials and so on.But silicon carbide is a strong covalent bondcompound,the diffusion coefficient of it is very low in high temperature environment,theself-diffusion coefficients of c and si are only1.5×10^-10cm²/s and2.5×10^-13cm²/s at hightemperature of2100℃,it is very difficult to sinter,they bring up the difficulties of thefabrication of SiC ceramic,the mass production of it is limited.Therefore,the current researchtopic is how to minimize the sintering temperature under the condition of impacting theproperties of sic ceramiacs as small as possible.This paper bases on the theory of the close packing,and designes the maximum densityof tricomponen composition for the desirably globular grains.Through the study for thesintering aids of AlN-Y₂O₃,Al₂O₃-Y₂O₃and clay,adjusting the sintering temperature,andsetting the optimum additive amount of antioxidant,SiC wear-resistant material has beenobtained by presureless sintering.Through analysis of the density,hardness,bendingstrength,abrasion resistance,and the microstructure of SiC wear-resistant material by x-raydiffraction and scanning electron microscopy,it shows that design of the grain compositioncan get the maximum bulk density and the shortest distance between particles,and this isbeneficial for the diffusion during the sintering process,and reduces the power required of thedensification.The appropriate types,quantity,and ratio of sintering aids forms the liquidphase,which can play an active role in the activating system of sintering.It makes the particlesrearranged,benefits for decreasing the porosity of sintering body,improves the performance ofSiC wear-resistant materials,and reduces the sintering temperature.Antioxidant can effectivelyreduce the oxidation of SiC,and improve the performance of matrix.Through amount of experiments and analysis of mechanical properties and micro-struct-ure of SiC wear-resistant material,it shows that SiC wear-resistant material can be sintered atthe temperature of1500℃for3h in the air atmosphere.When the diameter of SiC particles is4:3:1,the mass ratio of them is17:7:1,the optimum ratio of the sintering aids of AlN-Y₂O₃is30:70,8%the sintering aids of AlN-Y₂O₃,4%anorthite,0.4%B₄C and2.5%silicon metal are added,the SiC wear-resistant material can get the best performance.In this situation,it has awear weight loss of0.0075g/min,a density of2.776g/cm³,a water absorption of2.6%,ahardness of2710HV,and a flexural strength of162MPa.