Papers by Author: Jun Cong Wei

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Authors: Jun Cong Wei, Shu Xian Liu, Sen Sen Niu, Wei Ping Ma, Jun Bo Tu
Abstract: Al2O3-MgO unfired brick were prepared by using brown corundum, white corundum, fused magnesia and α-A12O3 as main starting materials, Al2O3-SiO2 gel powder as a binder. The effects of Al2O3-SiO2 gel powder on the strength of Al2O3-MgO unfired bricks were investigated. The phase composition was characterized by X-ray diffraction (XRD). The results showed that with an increase of Al2O3-SiO2 gel powder content, room temperature strength first increased and then decreased, and reached an optimum value at 5.5% addition. The hot modulus of rupture continuously increased. This mainly was related to the reactivity of Al2O3-SiO2 gel powder and the formation of mullite at high temperature.
546
Authors: Jun Cong Wei, Li Ai, Xiu Mei Ji, Jun Bo Tu
Abstract: Unfired Al2O3-C slides were prepared by using tabular corundum, reactive Al2O3 and fused alumina zirconia (FAZ) as main starting materials, Al powder and Si powder as anti-oxidation agents, phenolic resin as a binder. The effects of addition of fused alumina zirconia on the room temperature physical properties and hot modulus of rupture (HMOR) of unfired Al2O3-C slide were investigated. The phase composition and microstructure were investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS). The results showed that with the increase of fused alumina zirconia content, bulk density of the specimens after dried increased, apparent porosity decreased and high temperature strength increased. Phase transformation in ZrO2 could take place at different temperature, accompanying a volumetric expansion and microcrack formation. This would lead to a first increase and then decrease in HMOR. A maximum value was reached at 11 wt. % ZrO2. The thickness of decarbonization increased with increasing ZrO2 content.
550
Authors: Jun Cong Wei, Jun Bo Tu
Abstract: Based on the Al-O-N phase stable diagram and adopting inverse reaction sintering process, corundum-silicon nitride composite refractories were prepared using corundum, silicon nitride, clay and aluminium powder as the main starting materials. The specimens were sintered at 1600 for 3 hours under air atmosphere with different oxygen partial pressure obtained by addition of different amount of aluminium powder. The effects of aluminium powder additions(0, 4wt.%, 8 wt.% and 12 wt.% respectively) on the hot modulus of rupture were investigated .The phase composition and microstructure were tested by means of XRD, SEM and EDAS.The results showed that aluminium would be oxidized, nitrided and displaced as aluminium powder increased during sintering, which reduced the oxygen partial pressure in the specimen. The hot modulus of rupture (HMOR) increased considerably due to large amounts of fibrous sialon formed.
3960
Authors: Jun Cong Wei, Jun Bo Tu, Jian Cao
Abstract: Molten iron corrosion resistance of silicon-corundum-silicon nitride composites were investigated using corundum, silicon nitride, clay and silicon powder as the main starting materials by static crucible method. The corrosion mechanism of the composites was analyzed by means of scanning electron microscope (SEM with EDS). The results revealed that corundum-silicon nitride composites possessed good molten iron corrosion behavior and the active oxidation of silicon nitride was the main reason for loose structure of the corroded specimen; The composites produced a dense layer by addition of silicon, which made superior molten iron corrosion resistance behavior.
210
Authors: Jun Cong Wei, Sen Sen Niu, Yi Long Wang, Wei Ping Ma, Jun Bo Tu
Abstract: Al2O3-MgO unfired bricks were prepared by using brown corundum, white corundum, fused magnesia and α-A12O3 micropowder as main starting materials, Al2O3-SiO2 gel powder as a binder. The effects of magnesia fines addition on physical performance of Al2O3-MgO unfired bricks were investigated. The phase composition and microstructure were investigated by means of X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDS). The results showed that with the increase of magnesia fines addition, bulk density of Al2O3-MgO unfired bricks after dried decreased and strength increased. After heat treatment at 1100 °C, apparent porosity (AP) slightly reduced, bulk density (BD) slightly increased. Strength had little change. After heat treatment at 1500 °C, AP first decreased and then increased, and strength change correspondingly. The hot modulus of rupture (HMOR) first increased and then decreased with increasing magnesia content. The optimum magnesia addition is at 6.0 wt. %.
554
Authors: Jun Cong Wei, Jian Kun Huang, Chun Hui Cao, Jun Bo Tu
Abstract: The effects of varying the additions of magnesium aluminate spinel (0, 3, 6, 9, 12 wt. %) on the physical properties and slag resistance of Al2O3-SiC-C based castables were investigated. The composition of the specimens was determined by X-Ray diffraction (XRD). The results revealed that the incorporation of appropriate amount of MgAl2O4 in Al2O3-SiC-C based castables could promote the sintering of the specimens, decrease apparent porosity, and improve bulk density and strength. The slag resistance of the castables was improved due to an increase in the viscosity of molten slag, caused by the solid solution of Fe2+ or Fe3+ ions from the molten slag in MgAl2O4. However, further addition would led to a decrease in slag resistance because much Mg2SiO4 was produced.
467
Authors: Jun Cong Wei, Xiu Mei Ji, Jian Kun Huang, Chun Hui Gao, Jun Bo Tu
Abstract: The effects of addition of silicon powder (1 wt. %) and Na2CO3 (converting to additional 0.5%, 1% Na2O) on the hot modulus of rupture (HMOR) of MgO-Al-C bricks were investigated. MgO-Al-C refractories were prepared by using fused magnesia and graphite flake as main starting materials, and Si, Na2CO3 or both as additives. Its phase composition and microstructure were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), and EDS. The results showed that the HMOR of MgO-Al-C bricks increased slightly with addition of Si powder. However, the HMOR decreased when adding Na2CO3 and Si powder together. Moreover, the HMOR deduced with the increase of Na2CO3 content. The mechanism is that Al powder reacted to form fibrous Al4C3 and AlN, which could improve the HMOR. When silicon was added, β-SiC and M2S were formed, which could fill the passages and pores. So the densification and strength were improved. The addition of Na2CO3 could promote the oxidation of Al powder to form Al2O3, and inhibit the formation of Al4C3 and AlN. Hence the strength of MgO-Al-C deduced.
662
Authors: Rui Sheng Wang, Jun Cong Wei, Jun Hong Zhao, Yong Wu He, Fu Hua Peng
Abstract: β-Sialon/ZrO2 composites were prepared using 10 wt. % β-Sialon powder (where the z =1, 2, 3, respectively) and 90 wt. % ZrO2 powder as the starting materials. The effects of the Z value of β-Sialon on the bulk density, apparent porosity, water absorption rate, room temperature modulus of rupture, thermal shock resistance, microstructure and composition of the composites were investigated. The microstructure of sintered specimens was analyzed by scanning electron microscope (SEM), and X-Ray diffraction (XRD). The results revealed that with increase of the Z value of β–Sialon, bulk density gradually increased, apparent porosity and water absorption rate gradually decreased. The specimen possessed a maximum MOR (71.46MPa) when the z=2. In carbon embedded condition, the residual strength ratio of the specimen reached 60% and the lowest thermal expansion rate was obtained (0.55%) when the z=1. The phase compositions were cubic ZrO2 (c-ZrO2) and monoclinic ZrO2 (m-ZrO2). β-Sialon/ZrO2 composites exhibited overall optimum performance when the z equals 2
471
Authors: Jun Cong Wei, Jun Bo Tu, Yi Long Wang, Lian Jin Zhang
Abstract: Based on thermal stability research, a binder for dry vibrating refractories was selected. A new environment-friendly dry vibrating refractory was prepared by adopting the selected binder. The permanent linear change, apparent porosity, bulk density, cold crushing strength (CCS) and modulus of rupture (MOR) of the specimens were tested by the chinese national standard. The dry vibration refractories were successfully used in the lining material for continuous casting tundish.
1335
Authors: Jun Cong Wei, Su Juan Yuan, Xiu Mei Ji, Li Xue Yu, Jun Bo Tu
Abstract: In order to improve the hydration resistance of MgO-Al-C bricks, Fe2O3 was chosen as an additive according to thermodynamic calculations. MgO-Al-C refractories were prepared by using Si, Fe2O3 or both as additives. The effects of additives on the hydration resistance of specimens were investigated. XRD was conducted to determine the phase composition. The results showed that the hydration resistance of MgO-Al-C bricks would be slightly bettered with addition of only Si. However, it was helpful when Fe2O3 was added along with Si. The mechanism is that Fe2O3 could decompose to give off oxygen during heating, which could promote the oxidation of Al powder and inhibit the formation of Al4C3 and AlN.
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