The mullitization of andalusite from Xinjiang, Chi- na and influence of aggregates on properties of alumino- silicate refractories were studied by XRD, SEM, EDS, DSC. It was found that mullitization was obvious at 1 4...The mullitization of andalusite from Xinjiang, Chi- na and influence of aggregates on properties of alumino- silicate refractories were studied by XRD, SEM, EDS, DSC. It was found that mullitization was obvious at 1 400 ℃, but considerable at 1 500 ℃. The refractories with corundum aggregates had the highest RUL and the lowest creep rate, but refractories with bauxite aggregates had the lowest RUL and the highest creep rate.展开更多
The effect of tempering temperature on the microstructure and mechanical properties of ultra-high strength, copperbearing, low-carbon bainitic steel has been investigated in the experiment. The results showed that the...The effect of tempering temperature on the microstructure and mechanical properties of ultra-high strength, copperbearing, low-carbon bainitic steel has been investigated in the experiment. The results showed that the microstructure was mainly the laths of bainite in the as-quenched steel. The bainitic laths were restored and combined after the steel tempered at various tempera- tures. There were rnartensite/austenite （M/A） islands and numerous dislocations within and between the bainitic laths, while very t-me precipitates of ε-Cu were also observed within the laths. With increasing the tempered temperature from 400 to 600℃, the yield strength （YS） increased from 877 to 957 MPa, whereas the ultimate tensile strength （UTS） decreased from 1020 to 985 MPa. The Charpy V-notch （CVN） varied from 68.5 to 42 J, and the value was minimal for the steel tempered at 500℃. 2008 University of Science and Technology Beijing. All rights reserved.展开更多
This paper summarizes the pollution, situation and solutions of chrome bearing materials used in high temperature industry. Hexavalent chromium compounds are readily soluble in water and associated with carcinogen. Th...This paper summarizes the pollution, situation and solutions of chrome bearing materials used in high temperature industry. Hexavalent chromium compounds are readily soluble in water and associated with carcinogen. Therefore, serious environmental problems appeal for the study and application of chrome free materials. Chrome free products include： magnesia based materials, dolomite based materials, magnesia spinel materials, magnesia hercynite or magnesia galaxite materials and zirconia containing materials,and other substitutes. Although any product has its advantages and disadvantages, the trend to development of chrome free products is inevitable.展开更多
The Al-AlN bonded corundum based refractories was synthesized with the starting materials of fused alumina and metallic aluminium in nitrogen atmosphere through in-situ reaction. The study indicated that with the addi...The Al-AlN bonded corundum based refractories was synthesized with the starting materials of fused alumina and metallic aluminium in nitrogen atmosphere through in-situ reaction. The study indicated that with the addition of 14% metallic aluminium （13% of Al powder and 1% of Al fiber） , the material nitridized at 1100℃ for 3h has excellent physical properties. It is found that a massive quantity of alN in the forms of both whiskers and hexagon pellet particles is formed, and a large quantity of Al remained in the matrix. This multiple bonding system resulted in the excellent mechanical properties of the material. It is also found that the hydration tendency of the prepared material is inhibited, and the material exhibited excellent thermal shock resistance. The nature of protective oxidation of the bonding system is characterized. Thus, this material may become a new candidate of carbon-free sliding plate material for continuous casting.展开更多
Galaxite clinker as refractory starting material has been fabricated using chemically pure MnO2 and Al2O3 as starting materials at various processing atmospheres and temperatures under the guidance of thermodynamic si...Galaxite clinker as refractory starting material has been fabricated using chemically pure MnO2 and Al2O3 as starting materials at various processing atmospheres and temperatures under the guidance of thermodynamic simulation. A dense galaxite clinker can be synthesized at low cost under 0. 04% -99. 98% CO partial pressure created by coke bed in sealed sagger.展开更多
Simple three-point bending test at ambient tempera- ture characterized the mechanical behavior of burned Al2O3 -C refractories before and after thermal shock in association with the processing parameters （graphite co...Simple three-point bending test at ambient tempera- ture characterized the mechanical behavior of burned Al2O3 -C refractories before and after thermal shock in association with the processing parameters （graphite content and coking temperature, etc. ）. The results showed that non-linear plastic-elastic behavior under load lower than cold modulus of rupture （CMOR） was registered in all specimens and real linear elastic behavior could be identified after the first load, The total deformation could be divided into two parts, plastic and elastic areas. The graphite content and joint bonding system of carbon and ceramic phases were responsible for mechanical behavior of Al2O3 - C refractories.展开更多
The effect of Ti （ C, N） on properties of low-carbon MgO - C bricks was investigated. The phase composition and the microstructure of the matrix of low-carbon MgO - C brick containing Ti （ C, N） were studied by XR...The effect of Ti （ C, N） on properties of low-carbon MgO - C bricks was investigated. The phase composition and the microstructure of the matrix of low-carbon MgO - C brick containing Ti （ C, N） were studied by XRD and SEM analysis together with EDS. The results showed that Ti （ C, N） distributed in the matrix of lowcarbon MgO - C brick uniformly after being treated at 1 600 ~C for 3 h in coke powder bed, and Ti （C, N） and MgO formed a solid solution. After the treatment at 1 600 ℃ for 3 h in coke powder bed, the bulk density and cold crushing strength of low-carbon MgO - C brick with Ti （ C, N） decreased, and the apparent porosity and linear change rate of specimens increased. The oxidation resistance of low-carbon MgO - C brick with Ti（ C, N） was superior to that of low-carbon MgO - C brick with no additives, but inferior to that of low-car- bon MgO - C brick with Al powder. The slag resistance of the specimen with Ti （ C, N） was excellent as well.展开更多
文摘The mullitization of andalusite from Xinjiang, Chi- na and influence of aggregates on properties of alumino- silicate refractories were studied by XRD, SEM, EDS, DSC. It was found that mullitization was obvious at 1 400 ℃, but considerable at 1 500 ℃. The refractories with corundum aggregates had the highest RUL and the lowest creep rate, but refractories with bauxite aggregates had the lowest RUL and the highest creep rate.
文摘The effect of tempering temperature on the microstructure and mechanical properties of ultra-high strength, copperbearing, low-carbon bainitic steel has been investigated in the experiment. The results showed that the microstructure was mainly the laths of bainite in the as-quenched steel. The bainitic laths were restored and combined after the steel tempered at various tempera- tures. There were rnartensite/austenite （M/A） islands and numerous dislocations within and between the bainitic laths, while very t-me precipitates of ε-Cu were also observed within the laths. With increasing the tempered temperature from 400 to 600℃, the yield strength （YS） increased from 877 to 957 MPa, whereas the ultimate tensile strength （UTS） decreased from 1020 to 985 MPa. The Charpy V-notch （CVN） varied from 68.5 to 42 J, and the value was minimal for the steel tempered at 500℃. 2008 University of Science and Technology Beijing. All rights reserved.
文摘This paper summarizes the pollution, situation and solutions of chrome bearing materials used in high temperature industry. Hexavalent chromium compounds are readily soluble in water and associated with carcinogen. Therefore, serious environmental problems appeal for the study and application of chrome free materials. Chrome free products include： magnesia based materials, dolomite based materials, magnesia spinel materials, magnesia hercynite or magnesia galaxite materials and zirconia containing materials,and other substitutes. Although any product has its advantages and disadvantages, the trend to development of chrome free products is inevitable.
文摘The Al-AlN bonded corundum based refractories was synthesized with the starting materials of fused alumina and metallic aluminium in nitrogen atmosphere through in-situ reaction. The study indicated that with the addition of 14% metallic aluminium （13% of Al powder and 1% of Al fiber） , the material nitridized at 1100℃ for 3h has excellent physical properties. It is found that a massive quantity of alN in the forms of both whiskers and hexagon pellet particles is formed, and a large quantity of Al remained in the matrix. This multiple bonding system resulted in the excellent mechanical properties of the material. It is also found that the hydration tendency of the prepared material is inhibited, and the material exhibited excellent thermal shock resistance. The nature of protective oxidation of the bonding system is characterized. Thus, this material may become a new candidate of carbon-free sliding plate material for continuous casting.
文摘Galaxite clinker as refractory starting material has been fabricated using chemically pure MnO2 and Al2O3 as starting materials at various processing atmospheres and temperatures under the guidance of thermodynamic simulation. A dense galaxite clinker can be synthesized at low cost under 0. 04% -99. 98% CO partial pressure created by coke bed in sealed sagger.
文摘Simple three-point bending test at ambient tempera- ture characterized the mechanical behavior of burned Al2O3 -C refractories before and after thermal shock in association with the processing parameters （graphite content and coking temperature, etc. ）. The results showed that non-linear plastic-elastic behavior under load lower than cold modulus of rupture （CMOR） was registered in all specimens and real linear elastic behavior could be identified after the first load, The total deformation could be divided into two parts, plastic and elastic areas. The graphite content and joint bonding system of carbon and ceramic phases were responsible for mechanical behavior of Al2O3 - C refractories.
文摘The effect of Ti （ C, N） on properties of low-carbon MgO - C bricks was investigated. The phase composition and the microstructure of the matrix of low-carbon MgO - C brick containing Ti （ C, N） were studied by XRD and SEM analysis together with EDS. The results showed that Ti （ C, N） distributed in the matrix of lowcarbon MgO - C brick uniformly after being treated at 1 600 ~C for 3 h in coke powder bed, and Ti （C, N） and MgO formed a solid solution. After the treatment at 1 600 ℃ for 3 h in coke powder bed, the bulk density and cold crushing strength of low-carbon MgO - C brick with Ti （ C, N） decreased, and the apparent porosity and linear change rate of specimens increased. The oxidation resistance of low-carbon MgO - C brick with Ti（ C, N） was superior to that of low-carbon MgO - C brick with no additives, but inferior to that of low-car- bon MgO - C brick with Al powder. The slag resistance of the specimen with Ti （ C, N） was excellent as well.
