Liu X.,Zhengzhou University |
Niu Z.,Henan Boma Co. |
Xu E.,Zhengzhou University |
Zhu X.,Zhengzhou University |
Feng L.,Zhengzhou University
Proceedings of the Unified International Technical Conference on Refractories, UNITECR 2013 | Year: 2014
The A12O3-C material with Mg addition has been prepared by tabular alumina, ultra fine alumina, graphite and Mg as starting materials and resin as binder. The effects of Mg addition on phase composition, microstructure, physical and mechanical properties of unfired Al2O3-C material at different temperatures have been studied. The results show that Mg begins to react with CO or O2 to form MgO crystals at about 600°C which causes some expansion and consequently increases apparent porosity slightly, but cold and hot strength increase noticeably which is attributed to MgO crystals interspersed in the corundum skeleton structure creating strengthening effect. MgO initially reacts with Al2O3 to form MgAl2O4 at about 1000°C, the amount and size of MgAl2O4 increase with temperature from 1000°C to 1400°C. Due to strengthening effect of the in-situ formed MgAl2O4, cold and hot strength increase notably; but strength somewhat decreases after fired at 1400°C possibly due to micro-cracks resulting from expansion accompanying MgAl2O4 formation. © 2014 The American Ceramic Society.
Zhiwang N.,Henan Boma Co. |
Hui L.,Henan Boma Co. |
Xinhong L.,Henan Boma Co. |
Peizhong L.,Henan Boma Co. |
And 4 more authors.
Naihuo Cailiao/Refractories | Year: 2013
The metal composite unfired Al2O3-C slide plate specimens were prepared using tabular corun-dum, α-Al2O3 micropowder, flake graphite, aluminum powder and silicon powder as main starting materials, extra adding 4 mass% thermoset phenol formaldehyde resin and modified resin as binders. Effects of modified resin additions (0,1%,2% and 3%.,in mass) on properties of specimens fired at 400-1 000 °C in carbon embedded (graphite) condition and in air, respectively, were investigated. The results show that modified resin can obviously increase the strength at medium and low temperatures,but it has a little negative effect on oxidation resistance of the specimens. The unfired slide plates with 2% modified resin were used in a 120 t ladle and achieved a good effect. The average service life of the developed slide plates is 2.2 heats,and that of normal unfired slide plates without modified resin is 1.3 heats.
Chen H.,Henan Boma Co. |
Wang C.,Henan Boma Co.
Naihuo Cailiao/Refractories | Year: 2013
Three castables 0#, 1# and 2# were prepared in order to cut the production cost of ladle nozzle well block. The formulation of 0# castable is 70% (in mass, the same hereinafter) white fused corundum aggregate, 10% white fused corundum fines, 15% (α-Al2O3 micropowder+magnesium aluminate spinel+chrome oxide micropowder), and 5% calcium aluminate cement. For 1# castable, the equigranular Al2O3-Cr2O3 slag was used to completely replace the white fused corundum aggregate based on the 0# castable formulation. For the 2# castable, the Al2O3-Cr2O3 slag fines was used to completely replace the white fused corundum fines based on the 1# castable formulation. After stirring, vibratory compaction, curing, drying, and heating at 1100 and 1550°C, respectively, the density, strength, thermal shock resistance and slag corrosion resistance of the three castables were determined. The results indicate: (1) after drying at 110°C, compared with 0# castable, the bulk density of 1# castable changes a little, the apparent porosity increases slightly, and the modulus of rupture decreases slightly while the crushing strength improves significantly; but the performances of 2# castable decline in different degrees; (2) after heating at 1100 and 1550°C, the performances of 1# castable improve markedly; the hot modulus of rupture increases distinctly, the slag corrosion resistance is good, but the thermal shock resistance reduces; the performances of 2# castable decline evidently except for the hot modulus of rupture. The ladle nozzle upper well blocks prepared using the 1# castable formulation were used on a 60 t ladle in one steel plant, their service life without repair reached 80-90 heats, and the service life reached 110-120 heats after repairing, synchronized with the ladle life.