【摘要】 以电熔棕刚玉为骨料,碳化硅、白刚玉、硅粉、球沥青、硅微粉、氧化铝微粉及高铝水泥为细粉,按大颗粒、中颗粒、细粉的质量比为55∶15∶30配料,分别外加0、0.2%、0.4%、0.6%的碳化硼细粉,加水和少量减水剂共混后,振动成型为160 mm×40 mm×40 mm的试样。自然干燥24 h脱模后,再自然干燥24 h,在空气气氛中分别于800、1 000、1 200、1 550℃下热处理3 h。检测各温度热处理后试样的线变化率、显气孔率、体积密度、耐压强度、抗折强度以及抗氧化性,高温抗折强度是在空气气氛中于1 400℃0.5 h进行检测,并利用XRD分析部分试样经高温抗折试验后的物相组成。结果表明:由于B4C在较低温度下氧化产生少量液相,一方面促进了材料的烧结,增大了中温强度;另一方面在材料表面形成防氧化膜,阻碍了炭素材料的氧化,利于次生β-SiC的形成,因而增大了浇注料的高温抗折强度。在本试验条件下,B4C加入量为0.4%时,浇注料的力学性能最好。更多还原

【Abstract】 The specimens were prepared using fused brown corundum as aggregates,SiC,white corundum,silicon powder,ball pitch,microsilica,microalumina and high alumina cement as fine(the mass ratio among large particle,middle particle and fine was 55∶15∶30),adding into 0,0.2%,0.4% and 0.6% B4C fine,respectively,adding into water and a little water reducing agent and mixing,then shaping into 160 mm×40 mm×40 mm by vibration.After 24 h curing in mould and another 24 h curing after demoulding,the specimens were heat treated at 800,1 000,1 200 and 1 550 ℃ for 3 h in air,respectively.The permanent linear change,apparent porosity,bulk density,CCS,MOR,oxidation resistance,HMOR(at 1 400 ℃ for 0.5 h in air) of the specimen were determined,and the phase composition after high temperature rupture test was examined by XRD.The results showed that,at low temperature,B4C was oxidized and formed a little liquid phase,which could contribute to sintering and improve the medium temperature strength.Meanwhile,a antioxidation film was formed on the surface of the specimen,which could restrain the oxidation of carbon containing materials and contribute to the formation of secondary β-SiC phase,so the HMOR of the castables increased.Under the experimental conditions,the castables performed the best mechanical properties when 0.4% B4C was added.更多还原