In order to prolong the service life of castables for hot blast stove pipes,effects of SiO2 micropowder addition and aggregate kind on properties of castables for hot blast stove pipes,and properties of silica sol bon...In order to prolong the service life of castables for hot blast stove pipes,effects of SiO2 micropowder addition and aggregate kind on properties of castables for hot blast stove pipes,and properties of silica sol bonded castables were researched using homogenized bauxite,andalusite particles,andalusite fines,white fused corundum fines,α-Al2O3 micropowder,pure calcium aluminate cement,SiO2 micropowder,and silica sol as starting materials. The results show that：（1） as SiO2 micropowder addition increases,the shrinkage rate of fired specimens increases; BD increases firstly,reaches the highest at 4 mass%,and then decreases; CMOR and CCS of all specimens increase gradually; so the appropriate SiO2 micropowder addition is 4 mass%;（2） the specimens with bauxite aggregate have better CCS and volume stability,but specimens with andalusite aggregate have better thermal shock resistance;（ 3） for castables for hot blast stoves using silica sol as binder,the addition of pure calcium aluminate cement can decrease the linear change rate after treatment at 1 400℃ and can slightly enhance CCS and CMOR,but has very little influence on AP and BD; and the introduction of citric acid worsens the thermal shock resistance of specimens.展开更多
The magnesia - alumina based wet gunning mix was prepared using tabular corundum aggregates,fused mag- nesia aggregates, tabular corundum micropowder, silica mieropowder and pure calcium ahuninate cement as the main s...The magnesia - alumina based wet gunning mix was prepared using tabular corundum aggregates,fused mag- nesia aggregates, tabular corundum micropowder, silica mieropowder and pure calcium ahuninate cement as the main starting materials. Effects of silica micropowder ad- ditions （0, 0. 2% , 0. 5% , 1.0% , 1.5% , 2. 0% , and 2.5%, by mass, the same hewinafier） on properties oJ the gunning mix were researched. The results show that when ttze silica micropowder addition is i. 0% -2. 0% , the gunning mix has good .flou,ability and pumpability. Adding 2.5% silica micropowder, the nepheline forms at 1 600 ℃, which will reduce the high. temperature proper- ties of ntagnesia -ahtmina wet gunning mix. The intro- duction qf silica micropowder has obvious effects on cold mechanical properties of the gunning mix. For the speci- tnens dried at 110 ℃ , the strength increases slightly with the silica micropowder addition increasing. For the specimens heat-treated at 1 600 ℃ for 3 h, the strength in- creases nutrkedlv with the silica micropowder addition in- creasing. When keeping the water addition and particle size di, stribution constant, the residual linear expansion rate qf the specimen with 1.5% of silica micropowder is the lowest, ltot modulus tf rupture at 1 450 ℃ .for 0. 5 h oJ the specimens decreases gradually with the increase of silica fame addition. A small amount of silica micropow- der is beneficial for the slag penetration resistance.展开更多
文摘In order to prolong the service life of castables for hot blast stove pipes,effects of SiO2 micropowder addition and aggregate kind on properties of castables for hot blast stove pipes,and properties of silica sol bonded castables were researched using homogenized bauxite,andalusite particles,andalusite fines,white fused corundum fines,α-Al2O3 micropowder,pure calcium aluminate cement,SiO2 micropowder,and silica sol as starting materials. The results show that：（1） as SiO2 micropowder addition increases,the shrinkage rate of fired specimens increases; BD increases firstly,reaches the highest at 4 mass%,and then decreases; CMOR and CCS of all specimens increase gradually; so the appropriate SiO2 micropowder addition is 4 mass%;（2） the specimens with bauxite aggregate have better CCS and volume stability,but specimens with andalusite aggregate have better thermal shock resistance;（ 3） for castables for hot blast stoves using silica sol as binder,the addition of pure calcium aluminate cement can decrease the linear change rate after treatment at 1 400℃ and can slightly enhance CCS and CMOR,but has very little influence on AP and BD; and the introduction of citric acid worsens the thermal shock resistance of specimens.
文摘The magnesia - alumina based wet gunning mix was prepared using tabular corundum aggregates,fused mag- nesia aggregates, tabular corundum micropowder, silica mieropowder and pure calcium ahuninate cement as the main starting materials. Effects of silica micropowder ad- ditions （0, 0. 2% , 0. 5% , 1.0% , 1.5% , 2. 0% , and 2.5%, by mass, the same hewinafier） on properties oJ the gunning mix were researched. The results show that when ttze silica micropowder addition is i. 0% -2. 0% , the gunning mix has good .flou,ability and pumpability. Adding 2.5% silica micropowder, the nepheline forms at 1 600 ℃, which will reduce the high. temperature proper- ties of ntagnesia -ahtmina wet gunning mix. The intro- duction qf silica micropowder has obvious effects on cold mechanical properties of the gunning mix. For the speci- tnens dried at 110 ℃ , the strength increases slightly with the silica micropowder addition increasing. For the specimens heat-treated at 1 600 ℃ for 3 h, the strength in- creases nutrkedlv with the silica micropowder addition in- creasing. When keeping the water addition and particle size di, stribution constant, the residual linear expansion rate qf the specimen with 1.5% of silica micropowder is the lowest, ltot modulus tf rupture at 1 450 ℃ .for 0. 5 h oJ the specimens decreases gradually with the increase of silica fame addition. A small amount of silica micropow- der is beneficial for the slag penetration resistance.
