In this study,zirconia containing refractory samples were decomposed by dilute nitric acid.The chloride ion content in the leaching solution was determined by thiocyanate spectrophotometry.The influences of the leachi...In this study,zirconia containing refractory samples were decomposed by dilute nitric acid.The chloride ion content in the leaching solution was determined by thiocyanate spectrophotometry.The influences of the leaching method of the sample pretreatment and the coloration condition of the solution to be tested on the test results were studied.The precision test was carried out and the results were compared with those determined by ion chromatography.The results showed that the zirconia containing refractories were boiled with dilute nitric acid to obtain the test solution.The influence of zirconium hydrolysis on determination was removed by centrifugation.The chlorine contents in zirconia containing refractories determined by spectrophotometry have low relative standard deviation(RSD),showing slight testing difference with those determined by ion chromatograghy.展开更多
Based on the relevant phase diagrams of ternary system in MgO - CaO - ZrO2 - SiO2 quarternary systems, the phase diagram of Fe - O system and the condensed phase stability area diagram of iron oxides, the corrosion re...Based on the relevant phase diagrams of ternary system in MgO - CaO - ZrO2 - SiO2 quarternary systems, the phase diagram of Fe - O system and the condensed phase stability area diagram of iron oxides, the corrosion resistance of MgO - CaO - ZrO2 refractories to silicate cement, and the forming conditions and prepar- ing measures of hercynite are analyzed.展开更多
Oxidation of carbon is the main problem or Al2O3 - C refractories. ZrO2 - nitrides composite powder was synthesized through carbothermal reduction and nitridation （CRN） of zircon. The effect of ZrO2 - nitrides compo...Oxidation of carbon is the main problem or Al2O3 - C refractories. ZrO2 - nitrides composite powder was synthesized through carbothermal reduction and nitridation （CRN） of zircon. The effect of ZrO2 - nitrides composite powder addition on oxidation resistance of the Al2O3 - C refractories was investigated by measuring the thickness of oxidation layer. Phase compositions of the Al2O3 - C refractories before and after oxidation were investigated by X-ray diffraction （ XRD ）. Results show that the oxidation resistance of the Al2O3 - C refractories can be obviously improved by adding the synthesized ZrO2 - nitrides composite powder. The formation of mullite and zircon in the oxidation layer results in the densification of oxidation layer, which prevents oxygen diffusion and bnproves the oxidation resistance of the Al2O3 - C refractories.展开更多
In order to improve oxidation resistance and ther- mal shock resistance of Al2O3-C refractories, two groups of specimens were prepared with phenolic resin as binder, adding 0, 2 wt% , 4 wt% and 6 wt% commercial SiC or...In order to improve oxidation resistance and ther- mal shock resistance of Al2O3-C refractories, two groups of specimens were prepared with phenolic resin as binder, adding 0, 2 wt% , 4 wt% and 6 wt% commercial SiC or ZrO2-SiC composite powder synthesized from zircon respectively to Al2O3- C refractories, pressing at 200 MPa, drying fully at 250℃, and then carbon embedded firing at 1400℃ for 2 h. Oxidation resistance and thermal shock resistance were researched, phase composition was analyzed by XRD. The results showed that the oxidation of SiC in additives could protect carbon in specimens effectively and thus decreased the mass loss ratio and oxidation area, and improved the oxidation resistance of the specimen. Thermal shock resistance was improved owing to the micro crack toughening of ZrO2 and grain toughening of SiC. In this experiment, the specimens with 6 wt% ZrO2 -SiC composite powder or 6 wt% SiC powder had the best oxidation resistance and thermal shock resistance.展开更多
Using tabular alumina as aggregate,tabular alumina fines,reactive alumina ultra-fines,aluminum powders,silicon powders,carbon black,flake graphite,B4 C and zircon fines as matrix,low carbon Al2O3-C refractories were p...Using tabular alumina as aggregate,tabular alumina fines,reactive alumina ultra-fines,aluminum powders,silicon powders,carbon black,flake graphite,B4 C and zircon fines as matrix,low carbon Al2O3-C refractories were prepared.Influences of zircon powders additions （0,3%,5% and 7%,in mass,the same hereinafter） on properties,phase composition and microstructure were investigated.The results show that the ZrO2-nitride can be in-situ formed through carbothermal reduction and nitridation in Al2O3-C refractories.With the increase of zircon powder,the oxidation resistance of the Al2O3-C refractories improves obviously,the oxidized layer thickness decreases from 7.94 mm without zircon to 2.71 mm with 5% zircon.HMOR at 1 400 ℃ of the Al2O3-C refractories reaches the maximum 14.9 MPa when zircon addition is 5%.With the increase of zircon powder,the apparent porosity and bulk density change a little,CMOR and CCS increase.展开更多
ZrO2 -containing refractories have been increasingly used for cement rotary kilns. This paper discusses how the properties and performance of ZrO2-containing refractories are improved in terms of chemical attack resis...ZrO2 -containing refractories have been increasingly used for cement rotary kilns. This paper discusses how the properties and performance of ZrO2-containing refractories are improved in terms of chemical attack resistance, thermal shock resistance , thermal conductivity and mechanical stress.展开更多
Magnesia-based refractories hold a big share in the total refractories output in China because of abundance of magnesite resource. In this paper a short review has been focused on the current and future new use of mag...Magnesia-based refractories hold a big share in the total refractories output in China because of abundance of magnesite resource. In this paper a short review has been focused on the current and future new use of magnesia in the production of magnesia-based products including low carbon MgO-C bricks, MgO- CaO bricks, MgO-based castables, MgO-CaO-Fe2O3 ramming mix and MgO-CaO-C bricks for low carbon steelmaking and clean steel making, magnesite ball for slag splashing, MgO-CaO-ZrO2 for sintering and transfering zones of cement kiln and MgAlON for special use in the steel industry.展开更多
In this paper we present the results of studies on making MgO zirconia sintered parts（ intended to be used as metering nozzles in continuous casting of steel） from monoclinic zirconia and MgO powders via a granulati...In this paper we present the results of studies on making MgO zirconia sintered parts（ intended to be used as metering nozzles in continuous casting of steel） from monoclinic zirconia and MgO powders via a granulation process. The parts were pressed and sintered under different conditions,and analysed for physical properties,microstructure and phase composition. We found a strong influence of the MgO concentration and the sintering cycle,especially the cooling rate on the thermal shock resistance. The paper concludes with recommendations for the production of zirconia metering nozzles in an economic way.展开更多
The fused cast alumina-zirconia-silica(AZS)refractory is an indispensable material of the glass melting furnace,because of its outstanding corrosion resistance and low pollution to glass production.The exudation is on...The fused cast alumina-zirconia-silica(AZS)refractory is an indispensable material of the glass melting furnace,because of its outstanding corrosion resistance and low pollution to glass production.The exudation is one important index to evaluate the performance of fused cast AZS refractory products.In order to study the effects of chemical composition and microstructure on the exudation of fused cast AZS refractory materials,three types of fused-cast AZS refractory bricks(AZS33#,AZS36#and AZS41#)were selected from several companies as the research object,and their composition,bulk density,apparent porosity,the value of exudation,static corrosion rate and microstructure were discussed.The results show that the chemical composition,especially the content of SiO2 and Na2O,and the distribution of zirconia would greatly affect the content and viscosity of glass phase,thus affecting the glass exudation.This work will provide technical reference for the development of low exudation AZS refractories.展开更多
The oxidation behaviors of fused zirconium diboride and chemosynthetic zirconium diboride as well as morphology and composition of their oxidation products were researched by FESEM-EDS and XRD.The two kinds of zirconi...The oxidation behaviors of fused zirconium diboride and chemosynthetic zirconium diboride as well as morphology and composition of their oxidation products were researched by FESEM-EDS and XRD.The two kinds of zirconium diboride were heated at 700℃,900℃,1100℃and 1300℃for 3 h in air,respectively.The results show that Zr02 and B203(Ⅰ)are generated from the chemosynthetic zirconium diboride oxidized at 700℃for 3 h or the fused zirconium diboride oxidized at 800℃for 24 h;B203(Ⅰ)dissolves into water and then H3B03 crystallizes.展开更多
文摘In this study,zirconia containing refractory samples were decomposed by dilute nitric acid.The chloride ion content in the leaching solution was determined by thiocyanate spectrophotometry.The influences of the leaching method of the sample pretreatment and the coloration condition of the solution to be tested on the test results were studied.The precision test was carried out and the results were compared with those determined by ion chromatography.The results showed that the zirconia containing refractories were boiled with dilute nitric acid to obtain the test solution.The influence of zirconium hydrolysis on determination was removed by centrifugation.The chlorine contents in zirconia containing refractories determined by spectrophotometry have low relative standard deviation(RSD),showing slight testing difference with those determined by ion chromatograghy.
文摘Based on the relevant phase diagrams of ternary system in MgO - CaO - ZrO2 - SiO2 quarternary systems, the phase diagram of Fe - O system and the condensed phase stability area diagram of iron oxides, the corrosion resistance of MgO - CaO - ZrO2 refractories to silicate cement, and the forming conditions and prepar- ing measures of hercynite are analyzed.
文摘Oxidation of carbon is the main problem or Al2O3 - C refractories. ZrO2 - nitrides composite powder was synthesized through carbothermal reduction and nitridation （CRN） of zircon. The effect of ZrO2 - nitrides composite powder addition on oxidation resistance of the Al2O3 - C refractories was investigated by measuring the thickness of oxidation layer. Phase compositions of the Al2O3 - C refractories before and after oxidation were investigated by X-ray diffraction （ XRD ）. Results show that the oxidation resistance of the Al2O3 - C refractories can be obviously improved by adding the synthesized ZrO2 - nitrides composite powder. The formation of mullite and zircon in the oxidation layer results in the densification of oxidation layer, which prevents oxygen diffusion and bnproves the oxidation resistance of the Al2O3 - C refractories.
文摘In order to improve oxidation resistance and ther- mal shock resistance of Al2O3-C refractories, two groups of specimens were prepared with phenolic resin as binder, adding 0, 2 wt% , 4 wt% and 6 wt% commercial SiC or ZrO2-SiC composite powder synthesized from zircon respectively to Al2O3- C refractories, pressing at 200 MPa, drying fully at 250℃, and then carbon embedded firing at 1400℃ for 2 h. Oxidation resistance and thermal shock resistance were researched, phase composition was analyzed by XRD. The results showed that the oxidation of SiC in additives could protect carbon in specimens effectively and thus decreased the mass loss ratio and oxidation area, and improved the oxidation resistance of the specimen. Thermal shock resistance was improved owing to the micro crack toughening of ZrO2 and grain toughening of SiC. In this experiment, the specimens with 6 wt% ZrO2 -SiC composite powder or 6 wt% SiC powder had the best oxidation resistance and thermal shock resistance.
基金the Natural Science Foundation of Henan Educational Committee ( N0. 2011B430011 and N0. 13B430991)
文摘Using tabular alumina as aggregate,tabular alumina fines,reactive alumina ultra-fines,aluminum powders,silicon powders,carbon black,flake graphite,B4 C and zircon fines as matrix,low carbon Al2O3-C refractories were prepared.Influences of zircon powders additions （0,3%,5% and 7%,in mass,the same hereinafter） on properties,phase composition and microstructure were investigated.The results show that the ZrO2-nitride can be in-situ formed through carbothermal reduction and nitridation in Al2O3-C refractories.With the increase of zircon powder,the oxidation resistance of the Al2O3-C refractories improves obviously,the oxidized layer thickness decreases from 7.94 mm without zircon to 2.71 mm with 5% zircon.HMOR at 1 400 ℃ of the Al2O3-C refractories reaches the maximum 14.9 MPa when zircon addition is 5%.With the increase of zircon powder,the apparent porosity and bulk density change a little,CMOR and CCS increase.
文摘ZrO2 -containing refractories have been increasingly used for cement rotary kilns. This paper discusses how the properties and performance of ZrO2-containing refractories are improved in terms of chemical attack resistance, thermal shock resistance , thermal conductivity and mechanical stress.
文摘Magnesia-based refractories hold a big share in the total refractories output in China because of abundance of magnesite resource. In this paper a short review has been focused on the current and future new use of magnesia in the production of magnesia-based products including low carbon MgO-C bricks, MgO- CaO bricks, MgO-based castables, MgO-CaO-Fe2O3 ramming mix and MgO-CaO-C bricks for low carbon steelmaking and clean steel making, magnesite ball for slag splashing, MgO-CaO-ZrO2 for sintering and transfering zones of cement kiln and MgAlON for special use in the steel industry.
文摘In this paper we present the results of studies on making MgO zirconia sintered parts（ intended to be used as metering nozzles in continuous casting of steel） from monoclinic zirconia and MgO powders via a granulation process. The parts were pressed and sintered under different conditions,and analysed for physical properties,microstructure and phase composition. We found a strong influence of the MgO concentration and the sintering cycle,especially the cooling rate on the thermal shock resistance. The paper concludes with recommendations for the production of zirconia metering nozzles in an economic way.
文摘The fused cast alumina-zirconia-silica(AZS)refractory is an indispensable material of the glass melting furnace,because of its outstanding corrosion resistance and low pollution to glass production.The exudation is one important index to evaluate the performance of fused cast AZS refractory products.In order to study the effects of chemical composition and microstructure on the exudation of fused cast AZS refractory materials,three types of fused-cast AZS refractory bricks(AZS33#,AZS36#and AZS41#)were selected from several companies as the research object,and their composition,bulk density,apparent porosity,the value of exudation,static corrosion rate and microstructure were discussed.The results show that the chemical composition,especially the content of SiO2 and Na2O,and the distribution of zirconia would greatly affect the content and viscosity of glass phase,thus affecting the glass exudation.This work will provide technical reference for the development of low exudation AZS refractories.
文摘The oxidation behaviors of fused zirconium diboride and chemosynthetic zirconium diboride as well as morphology and composition of their oxidation products were researched by FESEM-EDS and XRD.The two kinds of zirconium diboride were heated at 700℃,900℃,1100℃and 1300℃for 3 h in air,respectively.The results show that Zr02 and B203(Ⅰ)are generated from the chemosynthetic zirconium diboride oxidized at 700℃for 3 h or the fused zirconium diboride oxidized at 800℃for 24 h;B203(Ⅰ)dissolves into water and then H3B03 crystallizes.
