The Effect of Al2O3（Mul.） on Phase Compositions of O′—Sialon Cermics

O′-Sialon Cermics are formed by reaction sintering of silicon nitride and silica with Al2O3(Y2O3) additive,The phase compositions of O′-Sialon Cermics are highly affected by addition of Al2O3( mul.) and are measured by X-ray diffraction techinque.The range of additions which could impaire the stucture of O′-Sialon Cermics is given in this article.     

Microstructures and Corrosion Resistance of Al2O3—C Based Refractories to the Melts Containing Titania

The corrosion resisance of the Al2O3-C based refrac-tories in melts containing titania has been studied by quasi-station immersion and rotary immersionThe corrosion rate is decreased with the addition of graphite carbon and ZrO2 in the refractories.The corrosion mehanism of Al2O3-C refractories is the oxidization of graphite carbon by the oxides of the melts and the formation of deteriorate layer,For the Al2O3-C-ZrO2 refractories,the corrosion behavior is due to the interaction between melts and refrac-tories,The new compounds of FeO.SiO2,SiZrO4,Feo.3CaO,2CaO.SiO2 and CaO.SiO2 are formed in the deteriorate layer.     

Production and properties of Cr2O3 Raw Material for Refractories

There are many processes to produce Cr2O3 from chrome-ores,Different particle size ranges of Cr2O3 powder,fine pinment grade green Cr2O3 and coarse metallurgy grade black Cr2O3, are made by different processes in China,Green Cr2O3 as superfine and addition and metallurgy grade black Cr2O3 used to synthesize Cr2O3 grain can be applied to refractories.It is very difficult for high purity Cr2O3 to sinter to densification and TiO2 addition is contributed to densification of Cr2O3 sintered at high temperature,Cr2O3 grains with relative density of 91%-95% are gained by sintering Cr2O3 with TiO2 addition and electrofusing Cr2O3 raw materials.     

Influence of Synthesized Super Al2O3 Powder on the Properties of Alumina Castable

The in fluence of three different Al2O3 powder on self-flowing alumina castable was studied.Maximum compaction of sample was computed by Andresen Equation.The result showed that the Al2O3 powder.which has much smaller particle size,could improve the microstructure and the mechanical properties of castable under room temperature and high temperature.With the same powder size,the room tem perature strength of the castable added with Al2O3 powder properties of which were altered by adding mineralizing agent,was higher than that of the castable added with common Al2O3 powder ,but the flowability of these three different castable was almost the same.     

Effect of Additives on Sintering of Cr2O3 in Reductive Atmosphere

The influence of additives TiO2,Y2O3 and composite rare earth on sintering of Cr2O3 in reductive atmosphere was studied.Results show that TiO2 can effectively increase the sinteed density at low temperature,As the increase of sintering temperature,such kind of effect becomes more and more unobvious and finaly disappear at 1550℃.Moreover,Y2O3 and composite rare earth have negative effect on sintering.     

The Formation of γ—AlON Spinel in the Reaction of Al2O3—AlN—MgO System

The stabilization of γ-aluminium oxyni-tride spinel(γ-AlON) has been investigated by addition of MgO,MgAl2O4,etc.,in reaction process.The results indicated that there are wider solid solution areas near ,Al2O3-rich side in AlN-Al2O3-MgO ternary systems,The content of stabilized AlON phase in samples is related to heating temperatures,additives,etc.The lattice parameters of their AlON phases could be well describedby the equation: a0=0.7900 0.0375[MgO] 0.015[AlN](nm)     

Effects of Additives on Properties of Unburned MgO—Al2O3 Refractory

The influences of four kinds of additives added into the matrix of MgO-Al2O3 unbuned products were investigated,The results show that samples with proper MgO/Al2O3 ration and proper addition of Cr2O3(2%- 4%) have good thermal shock resistance and slag corrosion resistance as well,XRD and SEM determination results indicate that a kind of compound spinel(Mg,Al, Cr) O4 was formed and the microstucture of the samples are denser.     

Synthesis of high purity Li_2CO_3 and MgCO_3·3H_2O in a homogeneous-like organic phase

Herein, three kinds of Li_2CO_3 and two kinds of MgCO_3·3H_2O crystals are easily synthesized in a homogeneouslike organic phase. The morphology and size of synthesized crystals are controllable and adjustable in the single organic phase, with the morphology of Li_2CO_3 ranging from micro-flaky, flower to nanobranch, MgCO_3·3H_2O ranging from nanosphere to nanorod. Compared with coupled reaction and solvent extraction process, of which the crystallization process occurred in the interface of two phase, our proposed method made it possible that the crystallization process occurred in the single organic phase, which resulted in better crystal morphology.Moreover, the formation mechanism of different crystal morphologies is discussed, the results showed that the crystals in micron size and nano size are involved in two crystallization mechanism, the micron particles in the form of flake and flower-like is a typical radial growth, which means that the growth occurs by diffusion around a nucleus as starting point, while the reaction model for small particles should be similar to a water-in-oil structure. As the reaction carried out, the crystal should be restricted in a constrained organic structure.     

Microstructure and Grain Boundary Character of Al2O3—Mullite—ZrO2—SiC Ceramic Compostie

Microstructure and grain boundary character of hot pressed binary Al2O3(mullite,ZrO2)-SiC omposites and quaternary Al2O3-mullite-ZrO2-SiC composite were studied by electron microscopy and microanalysis,Results suggest that there exist grain boundary solid solutions due to elemental diffusion near SiC and matrix oxides grain boundaries.     

用于VOC回收的PVDMS-Al2O3中空纤维复合膜

Sorption isotherm of chloroform in polyvinyl dimethylsiloxane （PVDMS） polymer film was measured via the gravimetric method, and this film was confirmed experimentally to be good membrane material to recover chloroform from gas stream with high sorption capacity. A new PVDMS-Al2O3 composite hollow fibre membrane was further prepared by coating a PVDMS film on the outer surface of Al2O3 hollow fibre porpous substrate prepared by a dry/wet phase inversion method. Microstructure of the composite membranes was examined by scanning electron microscopy （SEM）, indicating the PVDMS coating layer was uniform, free of defects, and around 15μm thick. Performance of the PVDMS-Al2O3 composite hollow fibre membranes for chloroform recovery was investigated. By comparing the experimental data that derived from a mathematical model, the permeabilities of chloroform and nitrogen in the PVDMS polymer membrane were obtained. The effects of temperature and feed flow rate on the chloroform recovery and permeate concentration were investigated both experimentally and theoretically.     

Development of Self—flowing Al2O3—SiC—C Castable and Its Application to Troughs of Large Blast Furnaces

The developed self-flowing Al2O3-SiC-C castable for troughs of blast furnace(BF) can self-flow under its own gravity,leveling,degassing,compacting and setting without vibration by aplication of external energy,The self-flwoing castable with high strength,improved thermal shock resistance and good resistance to molten slag and hot metal,has been used to troughs of large blast furnace,resulting in molten iron throughput of more than 100000 tons.     

Sintering Behaviour of Al2O3-SiC-C Ramming Mix

Silicon fines, boron acid solid powders and microfine SiO2 as sintering agents were incorporated into Al2O3-SiC-C ramming mix in order to investigated their effects on the microstructure , mechanical properties and sintering behavior of the ramming mix. Results show that all the three agents could improved both densification and mehanical properties markedly, compared to that of non-agent specimens and the effect of the composite of boron acid solid powders and microfine SiO2 is the best. The oxidation resistance increased with the addition of agents, which is supported by densification. Microstructures showed that agent powders could fill pores or produce liquid phases at high temperature, therefore, improve the sintering of the ramming mix.     

The Preparation and Gas-sensing Property of Nanosize γ-Fe2O3／SiO2

Nanostructured γ-Fe2O3/SiO2 complex oxide was prepared by sol-gel method with tetraethoxysilane and iron nitrate as precursors. The particle size distribution, thermal and phase stabilities and gas sensing properties were systematically characterized by TEM, granularity distribution, TG-DTA, XRD and gas sensitivity measurements. The particle size is about 10 nm and size distribution is very narrow. The sensitivity of the sensing element to CO, H2, C2H4, C6H6 and the effects of calcination temperature on the sensitivity and conductance of gases were examined. The combination of excellent thermal stability and tunable gas sensing properties through careful control of the preparation and judicious selection of material compositions gives rise to novel nanocomposites, which is attractive for the sensitive and selective detection of reducing gases and some hydrocarbon gases.     

Application Study on β-Sialon-AI_2O_3 Brick in Iron Ladle

The microstructure and slag erosion fractal dimension of reaction interface of β-Sialon-Al2O3 brick used in 300 Mt iron ladle of Baosteel have been studied by SEM and XRD. The results indicated that β-Sialon-Al2O3 brick exhibited excellent slag resistance. The main wear mechanism of β-Sialon-Al2O3 brick is mainly from the spalling caused by thermal mechanical stress and attacked by slag secondly.     

Effects of Precursors for Preparing Intermediate Layer on the Performance of Ti/SnO2+Sb2O3/PbO2 Anode

The Ti/SnO2+Sb2O3/PbO2 anode with SnO2+Sb2O3 intermediate layer obtained by the polymeric precursor method (PPM) and with the conventional route was studied. The morphology and microstructure of SnO2+Sb2O3 intermediate layer derived from different precursors and the top PbO2 active layer were examined by means of ESEM and XRD. The lifetime and electrocatalytic activity of the anode were also assessed by the cyclic voltammetry and accelerated lifetime test in 1.0 mol/L H2SO4 solution. It was found that precursor solvents affected lifetime, microstructure and morphology of the anode, and had little influence on electrocatalysis activity of the electrodes. The accelerated lifetime of Ti/SnO2+Sb2O3/PbO2 anode with intermediate layer prepared by PPM was 29.5 h in 1.0 mol/L H2SO4 solution, which was respectively about four times and twice that of the anode prepared with ethylene glycol and ethanol. After the anode was subjected to thermal corrosion, the lifetime still reached 27 h in contrast to the others.     

WP/γ-Al2O3催化剂的制备、表征及加氢脱硫和加氢脱氮活性

Two series of WP/Al2O3 catalyst precursors with WP mass loading in the range 18.5%-37.1% were prepared using the impregnation method and mixing method, respectively, and the catalysts were then obtained by temperature-programmed reduction of supported tungsten phosphate (precursor of WP/Al2O3 catatlysts) in H2 at 650℃ for 4h. The catalysts were characterized by XRD, BET, TG/DTA, XPS and 31p MAS-NMR. The activities of these catalysts were tested in the hydrodenitrogenation (HDN) of pyridine and hydrodesulfurization (HDS) of thiophene at 340℃ and 3.0MPa. The results showed that owing to the stronger interaction of the support with the active species, the precursor of WP/Al2O3 catalyst was more difficultly phosphided and a greater amount of W species was in a high valence state W6 on the surface of the catalyst prepared by the impregnation method than that by the mixing method. 31p MAS-NMR results indicated that 31p shift from 85% H3PO4 of 2.55 × 10-4 for WP and 2.57 × 10-4 for WP/γ-Al2O3 catalysts prepared by mixing method. Such WP/Al2O3 catalysts showed higher HDN activities and lower HDS activities than those prepared by the impregnation method under the same loading of WP.WP/γ-Al2O3 catalysts with weak interaction between support and active species were favorable for HDN reaction while the WP/γ-Al2O3 catalysts with strong interaction were favorable for HDS reaction.     

Application Study onβ—Sialon—Al2O3 Brick in Iron Ladle

The microstructure and slag erosion fractal dimension of reaction interface of β-Sialon-Al2O3 brick used in 300 Mt iron ladle of Baosteel have been studied by SEM and XRD.The results indicated that β-Sialon-Al2O3 brick exhibited excellent slag resistance.The main wear mechanism of β-Sialon-Al2O3 brick is mainly from the spalling caused by thermal mechanical stress and attacked by slag secondly.     

Influence of Raw Material on the Properties of MgO—Al2O3—Cr2O3 Ramming Mixes

MgO-Al2O3-Cr2O3 ramming mixes made of different raw materials have different mineral structure and different physical properties though with the identical particle size distribution, the same amount of binder and chemical composition. The residual carbon content of the fused magnesia-chrome material made in reducing atmosphere is very high, if this materials is used in the MgO-Al2O3-Cr2O3 ramming mix, it would cause spalling of the furnace lining during drying-out.     

纳米固体超强酸SO2-4/Fe2O3的催化性能

In order to minimize the pollution of ferrous sulfate, a by-product of titanium dioxide, and increase the yield of synthetic ester, the SO4^2-/Fe2O3 nanosolid superacid has been produced by chemical precipitation and its micrographs was determined by SEM. The effect of preparation conditions of SO4^2-/Fe2O3 nanosolid superacid on catalysis synthesis butyl acetate and synthesis conditions of butyl acetate were studied. From experimental data, as compared with liquid acid, SO4^2-/Fe2O3 nanosolid superacid showed higher catalytic performance in catalytic synthesis of butyl acetate, and the yield of butyl acetate was obviously increased in the same reaction time.     

Effect of Al_2O_3-SiC Composite Powder on Properties of Al_2O_3-SiC一C Bricks

Al2O3- SiC- C specimens were prepared using white fused corundum( 3- 1,≤1 and ≤0. 044 mm),Al2O3- SiC composite powders( d50≤5 μm),α-Al2O3micropowder( d50= 1. 2 μm),SiC powder( ≤0. 044mm),flake graphite( ≤0. 088 mm),Si powder( d50= 42. 8 μm) and B4C powder( d50≤10 μm) as main starting materials,and thermosetting phenolic resin as binder. 4%,8%,12% and 16%( in mass,the same hereinafter) of Al2O3- SiC composite powders substituted the same quantity of α-Al2O3micropowder + SiC powder.Effects of composite powder additions on apparent porosity,bulk density,cold modulus of rupture,cold crushing strength,hot modulus of rupture( 1 400 ℃),therma shock resistance( 1 100 ℃,water quenching) and oxidation resistance( 1 000 and 1 500 ℃) of Al2O3- SiC- C specimens after 180 ℃ curing,1 000 ℃ 3 h carbon-embedded firing and 1 500 ℃ 3 h carbon-embedded firing,respectively,were researched. The results indicate that:( 1) with the increase of Al2O3- SiC composite powder,cold strengths of the cured specimens decline,those of the specimens fired at 1 000 ℃ change a little,and those of the specimens fired at 1 500 ℃ change a little except for an obvious improvement of cold crushing strength;( 2) with the increase of Al2O3- SiC composite powder,hot modulus of rupture at 1 400 ℃ decreasesand thermal shock resistance enhances significantly;( 3) when Al2O3- SiC composite powder addition is4%,the oxidation resistance at 1 500 ℃ is the best,and the reason may be the composite powder is finer and more active,which is beneficial to form dense mullite protective layer to retard the O2diffusion into the specimens.