结合剂对Al_2O_3-MgAl_2O_4-SiC-C质铁沟浇注料性能的影响

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

以电熔镁铝尖晶石(粒度为5～3mm、3～1mm)和电熔白刚玉颗粒(粒度<1mm)以及白刚玉细粉、碳化硅细粉、活性αAl2O3微粉、Si粉和球状沥青等为主要原料,在保持基料的配比不变的条件下分别采用铝酸钙水泥(w,3%)+SiO2微粉(w,2%)及ρAl2O3(w,4%)为结合剂,振动成型为Al2O3-MgAl2O4-SiC-C试样,室温养护24h后脱模,分别于110℃24h、1100℃3h和1500℃3h(埋炭)条件下热处理,然后测定试样的体积密度、显气孔率、线变化率、抗折强度、耐压强度和抗渣性。试验结果表明:铝酸钙水泥+SiO2微粉结合的浇注料流动性较好,经110℃24h、1100℃3h和1500℃3h(埋炭)热处理后,试样的显气孔率较小,体积密度较大,常温耐压强度和常温抗折强度优于以ρAl2O3为结合剂的;但是,采用铝酸钙水泥+SiO2微粉作结合剂的试样经1500℃埋炭3h处理后的线变化率较大,试样的高温抗折强度和抗侵蚀性能也明显低于ρAl2O3结合试样的。

AlO3 - MgAl2O4 - SiC - C specimens were prepared with fused magnesia - alumina spinel （5 - 3 mm,3 -1 mm）, white fused alumina （ 〈 1 mm）, white fused alumina powder, silicon carbide powder, α-Al2O3 micropowder,silicon powder and spherical pitch as starting materials. Calcium aluminate cement（ω,3%） ＋fume SiO2 （ ω,2% ） or ρ-Al2O3 （ ω,4% ） were added respectively as binder on the base of fixed proportioning ratio of starting materials. The specimens were demoulded after curing at room temperature for 24 h, then were heat-treated at 110 ℃ for 24 h,1100 ℃ for 3 h and 1500 ℃ for 3 h（carbon embedded） respectively. The bulk density, apparent porosity, linear change, modulus of rupture, cold crushing strength and corrosion resistance were determined. The result shows that the specimen using calcium aluminate cement ＋ ultrafine SiO2 as binder was characterized by better flowability and after heat treatment at 110 ℃ for 24 h, 1100℃ for 3 h and 1500 ℃ for 3 h （carbon embedded）, it exhibited lower porosity, higher bulk density, cold crushing strength and modulus of rupture compared with that using ρ-Al2O3 as binder. However,the linear change of the former after treatment at 1500 ℃ for 3 h （carbon embedded） was higher, and the HMOR and corrosion resistance were poorer.