尖晶石对Al_2O_3-SiC-C质铁沟浇注料性能的影响

Effect of MgAl_2O_4 on properties of Al_2O_3-SiC-C castables for iron runner

以新型亚白刚玉（8～5mm、5～3mm、3～1mm、≤1mm、≤0．044mm）、SiC（≤1mm、≤0．088mm）、尖晶石粉（≤0．044mm）、SiO2微粉、α-Al2O3微粉、铝酸钙水泥、Si粉和球状沥青等为主要原料，在Al2O3-SiC—C质铁沟浇注料的配料组成中分别加入质量分数为0、4％、7％、10％、13％的镁铝尖晶石粉，混练均匀后振动成型为40mm×40mm×160mm的条状试样和＋50／20mm×50／20mm的坩埚试样，经110℃24h和1450℃3h热处理后测定试样的体积密度、显气孔率、常温抗折强度、常温耐压强度、烧后线变化率和抗渣性能，并且进行了XRD、SEM和EDS分析。结果表明：加入适量镁铝尖晶石粉后，由于改善了试样的成型密度，促进了试样的烧结，因而提高了试样的密度、强度、体积稳定性和抗渣性；但是，由于尖晶石和刚玉的热膨胀系数不同，加入过多的镁铝尖晶石粉会导致试样中产生过多的微裂纹，从而对试样的密度、强度、体积稳定性和抗渣性不利；本试验中，尖晶石粉的最佳加入量（质量分数）为10％；尖晶石加入量为10％的试样中有长度为30～80μm的SiC晶须生成，并且其颗粒与基质之间结合紧密。

Al2O3 -SiC -C castables for iron runner with MgAl2O4 powder （0,4% ,7% ,10% ,13% respectively） were prepared with new type sub-white corundum（8-5 mm,5-3 mm,3- 1 mm, ≤1 mm and 〈0.044 mm）,SiC （≤1 mm and ≤0.088 mm） ,MgAl2O4 powder（ ≤0.044 mm）,ultrafine SiO2,α-Al2O3 micropowder,calcium aluminate cement,Si powder and spherical pitch as starting materials,milling well,vibrating moulding into the bar specimens of 40 mm x40 mm x160 mm and crucible specimens of Ф50/20 mm x50/20 mm,firing at 110 ℃ for 24 h and 1 450 ℃ for 3 h. Bulk density, apparent porosity, cold modulus of rupture, cold crushing strength, linear change rate and slag resistance of fired specimens were tested ,and the specimens were analyzed by XRD,SEM and EDS. The results show that：（ 1）Appropriate MgAl2O4 powder improves bulk density,strength ,volume stability and slag resistance of fired specimens because of improving the moulding density and sintering; （2）Because .spinel and corundum have different thermal expansion coefficients,the excess MgAl2O4 powder can result in excess micro-cracks forming in specimens,which is bad for density,strength,volume stability and slag resistance;（3）The optimum addition of MgAl2O4 powder is 10% ;（4）The specimen with 10% MgAl2O4 powder has 30 -80 μm SiC whisker and close bonding between particles and matrix.