分散剂及氧化铝微粉对钢包用Al_2O_3-MgO浇注料施工性能的影响

Effects of dispersive agent and alumina micropowder on workability of Al_2O_3-MgO castables for steel ladles

为了提高Al_2O_3-Mg O浇注料的施工性能,以板状刚玉颗粒(粒度分别为5~3、3~1、≤1 mm)和细粉(粒度≤0.074 mm)、电熔镁砂(粒度≤1 mm)、活性氧化铝微粉(PFR40、PBR和CL)、煅烧氧化铝微粉(AC34B5和CT)为主要原料,以铝酸钙水泥(Secar 71)为结合剂,以聚羧酸类减水剂WS、FS和AD为分散剂,制备了Al_2O_3-Mg O浇注料。研究了分散剂种类和外加量[分别为0.4%(w)的WS、0.2%(w)的FS和1%(w)的AD],单一活性氧化铝微粉种类(分别为PFR40和PBR),以及复合氧化铝微粉种类(分别为PFR40-AC34B5复合粉和CL-CT复合粉)及其复合比例(质量比,均从9/0逐渐减小至3/6)对浇注料的流动值及烘干后试样的显气孔率、体积密度、常温抗折强度和常温耐压强度的影响。结果表明:1)在加入单一氧化铝微粉PBR或PFR40时,外加0.4%(w)WS的浇注料的流动性能及烘干后试样的综合性能比外加0.2%(w)FS或1%(w)AD的好。2)加入PFR40-AC34B5复合粉的浇注料的流动值比加入CL-CT复合粉的浇注料的略大;随着PFR40与AC34B5或CL与CT复合比例的减小,浇注料的流动值及烘干后试样的致密度均呈减小趋势,烘干后试样的强度变化不大;但考虑到活性氧化铝微粉的价格较高,应选择合适的复合比例。

This work aims at enhancing the workability of Al2O3-MgO castables. Al2O3-MgO castables were prepared using tabular alumina particles （5 -3,3 -1, ≤1 mm） ,tabular alumina fines （ ≤0. 074 mm） ,fused magnesia （ ≤1 mm）, reactive alumina micropowder （ PFR40, PBR, and CL） and calcined alumina micropowder （AC34B5 and CT） as the main starting materials,calcium aluminate cement （Secar 71） as the binder, and polycarboxylic acid water reducer WS, FS, and AD as the dispersive agent, respectively. Effect of the dispersive agents （0.4 mass% WS,0.2 mass% FS or 1 mass% AD）, reactive alumina micropowder （PFR40 or PBR）, composite alumina micropowder （PFR40-AC34B5 or CL-CT, the ratio from 9/0 to 3/6） on the flow value of the castables as well as the apparent porosity, bulk density, cold crushing strength and cold modulus of rupture of the dried castable specimens were investigated. The results show that： （1）with PBR or PFR40,the castables with 0.4 mass% WS own better performance than those with 0.2 mass% FS or 1 mass% AD; （2）compared with the castables with CL-CT composite powder, the castables with PFR40-AC34B5 composite powder have slightly higher flow value;with the decreasing ratio of PFR40 to AC34B5, or the decreasing ratio of CL to CT,the castables have declined flow value and the dried castable specimens have decreased density but the mildly changed strength; in consideration of the high price of reactive alumina,a proper composite ratio shall be selected.