Preparation And Study On Properties Of SiAlON-SiC Composite Material

SiAlON-SiC composite material has been prepared by pressure molding and Gel-casting in air pressure sintering with Si,Al,SiO₂,and SiC as raw material.In research of the best craft of preparation by pressure molding, appropriate grainseries, content of cohered phase and sintering temperature have been found. The testresults show that material in highest performance is sintered for 2 hours at 1550℃,whichgrain series of raw material is mixed in proportion of 6:1:3 with 35 percent SiAlONphase according to molecular formula of Si₄Al₂O₂N₆ when the value of Z is equal to 2.During preparation by Gel-casting, influence rule of modified Si and Al to rheology inslurry suspension is studied. The test results show that modified Si powder restrains tohydrolyze and overcomes drawbacks that hydrolyzing speed and degree would increaseaccording to the consistence rise of [OH]^-, and modified Al powder has higher negativeZeta value, so that they are suitable to disperse steadily in the value 8.5 of pH. Besides,fineness influence of modified Si and Al to rheology in slurry suspension is studied.The test results show that the performance of Y1 is the best, that of Y2 inferior. Theperformance of Z1 is the better. Moreover, size shrinkage rate of Z1 is -0.167, while that ofY1 and Y2 is expansible to about 13%. Actual value of Z of SiAlON phase in SiAlON-SiCcomposite material is in some sort less than designed that, but both are very contiguous.Thermal shock resistance performance of SiAlON-SiC composite material is studied.The test results show that the trend of thermal shock resistance of Y1 and Y2 is similar, butZ1 show the better at 200℃to 1400℃. Resistance ability to corrosion in alkali of it isstudied. The test results show that resistance ability to corrosion Z1 is superior to that ofY1 and Y2 in fused alkali at 930℃and in alkali steam at 1200℃and 1500℃as a whole.Resistance ability to corrosion in CaCl₂ of it is studied. The test results show that blendingstrength of Y1 ,Y2 and Z1 increases in some sort and they all show benign resistanceability to corrosion in CaCl₂ at 930℃. As a whole, resistance ability to corrosion in CaCl₂of Z1 is superior to that of Y1 and Y2 at 1200℃and 1500℃.