Periclase-spinel bricks were prepared using sintered magnesia,flotation magnesia,fused magnesium aluminate spinel and calcined Al_(2)O_(3)fines as the starting materials and calcium lignosulfonate as the binder,mixing...Periclase-spinel bricks were prepared using sintered magnesia,flotation magnesia,fused magnesium aluminate spinel and calcined Al_(2)O_(3)fines as the starting materials and calcium lignosulfonate as the binder,mixing,shaping and firing at 1650℃.Flotation magnesia particles were used to replace ordinary sintered magnesia particles and different amounts of calcined Al_(2)O_(3)fines were extra-added(0%,3%and 5%,by mass)to investigate their effects on the properties of periclase-spinel bricks.The results show that:the periclase-spinel bricks prepared with flotation magnesia particles have reduced apparent porosity and cold compressive strength,and enhanced bulk density,thermal shock resistance,hot strength and hot toughness.As the calcined Al_(2)O_(3)fines addition increases,the apparent porosity and the cold compressive strength decrease,and the bulk density,the thermal shock resistance,the hot strength and the hot toughness are improved.展开更多
The magnesia -hercynite bricks offer a new lining to rotary cement kiln. They are well adopted and widely used in the high temperature zone of cement kiln, and have obtained good performance at rigorous and severe wor...The magnesia -hercynite bricks offer a new lining to rotary cement kiln. They are well adopted and widely used in the high temperature zone of cement kiln, and have obtained good performance at rigorous and severe working conditions. The synthesis of hercynite requires a suitable atmosphere with proper O2 partial pressures which makes sure FeO can stably exist at the synthesizing temperature. Current industrial production of hercynite mainly adopts fused method. The other method, sinte- ring method, is not mature and needs further research. The magnesia - hercynite brick shows high hot toughhess, high adhesion strength to kiln crust, and good corrosion resistance to alkali salt in cement kilns. The mismatching of thermal expansion between magnesia and hercynite can improve the thermal shock resistance of the bricks, but the oxidation of partial Fe^2＋ , the high temperature solution, and low temperature exsolution of transgranular secondary spinel lead to cubical expansion, .formation of more cracks, and poor thermal shock resistance of the bricks.展开更多
Currently the service life of CDQ shafts in China is mainly restricted by the properties of the inclined flue bricks.In this work,based on the systematic analysis of the damage mechanism of inclined flue refractories,...Currently the service life of CDQ shafts in China is mainly restricted by the properties of the inclined flue bricks.In this work,based on the systematic analysis of the damage mechanism of inclined flue refractories,high performance mullite-SiC bricks were developed.The bricks were produced by corundum,andalusite,SiC and other high purity raw materials.Metal silicon and alumina ultra micropowder were added to form dispersion multi-phase structure,fortifying the matrix and improving the microstructure.The products have excellent properties such as low porosity,high density,good wear resistance,high refractoriness under load,and good thermal shock resistance.The products can replace the ordinary mullite-SiC bricks and obtain a good service life.展开更多
In order to improve the thermal shock resistance of chrome-corundum bricks,different amounts of andalusite were added to the formulation of chrome-corundum bricks to replace the equivalent white fused corundum with th...In order to improve the thermal shock resistance of chrome-corundum bricks,different amounts of andalusite were added to the formulation of chrome-corundum bricks to replace the equivalent white fused corundum with the same particle size.After mixing,shaping,drying and firing,the density,the cold strength,the cold wear resistance,the hot modulus of rupture and the thermal shock resistance were tested.XRD,SEM and elemental surface scanning were used to characterize the specimens.The results show that:(1)the volume expansion of andalusite mullitization reduces the apparent porosity of chrome-corundum bricks;(2)the density and the hardness of mullite are lower than those of corundum so the decrease of the corundum content in brick leads to the decrease of the bulk density,the strength and the cold wear resistance;(3)the cross-distributed columnar mullite in the matrix can effectively improve the hot modulus of rupture and the thermal shock resistance of the specimens;(4)considering comprehensively,the andalusite addition shall not exceed 18%.展开更多
文摘Periclase-spinel bricks were prepared using sintered magnesia,flotation magnesia,fused magnesium aluminate spinel and calcined Al_(2)O_(3)fines as the starting materials and calcium lignosulfonate as the binder,mixing,shaping and firing at 1650℃.Flotation magnesia particles were used to replace ordinary sintered magnesia particles and different amounts of calcined Al_(2)O_(3)fines were extra-added(0%,3%and 5%,by mass)to investigate their effects on the properties of periclase-spinel bricks.The results show that:the periclase-spinel bricks prepared with flotation magnesia particles have reduced apparent porosity and cold compressive strength,and enhanced bulk density,thermal shock resistance,hot strength and hot toughness.As the calcined Al_(2)O_(3)fines addition increases,the apparent porosity and the cold compressive strength decrease,and the bulk density,the thermal shock resistance,the hot strength and the hot toughness are improved.
文摘The magnesia -hercynite bricks offer a new lining to rotary cement kiln. They are well adopted and widely used in the high temperature zone of cement kiln, and have obtained good performance at rigorous and severe working conditions. The synthesis of hercynite requires a suitable atmosphere with proper O2 partial pressures which makes sure FeO can stably exist at the synthesizing temperature. Current industrial production of hercynite mainly adopts fused method. The other method, sinte- ring method, is not mature and needs further research. The magnesia - hercynite brick shows high hot toughhess, high adhesion strength to kiln crust, and good corrosion resistance to alkali salt in cement kilns. The mismatching of thermal expansion between magnesia and hercynite can improve the thermal shock resistance of the bricks, but the oxidation of partial Fe^2＋ , the high temperature solution, and low temperature exsolution of transgranular secondary spinel lead to cubical expansion, .formation of more cracks, and poor thermal shock resistance of the bricks.
文摘Currently the service life of CDQ shafts in China is mainly restricted by the properties of the inclined flue bricks.In this work,based on the systematic analysis of the damage mechanism of inclined flue refractories,high performance mullite-SiC bricks were developed.The bricks were produced by corundum,andalusite,SiC and other high purity raw materials.Metal silicon and alumina ultra micropowder were added to form dispersion multi-phase structure,fortifying the matrix and improving the microstructure.The products have excellent properties such as low porosity,high density,good wear resistance,high refractoriness under load,and good thermal shock resistance.The products can replace the ordinary mullite-SiC bricks and obtain a good service life.
文摘In order to improve the thermal shock resistance of chrome-corundum bricks,different amounts of andalusite were added to the formulation of chrome-corundum bricks to replace the equivalent white fused corundum with the same particle size.After mixing,shaping,drying and firing,the density,the cold strength,the cold wear resistance,the hot modulus of rupture and the thermal shock resistance were tested.XRD,SEM and elemental surface scanning were used to characterize the specimens.The results show that:(1)the volume expansion of andalusite mullitization reduces the apparent porosity of chrome-corundum bricks;(2)the density and the hardness of mullite are lower than those of corundum so the decrease of the corundum content in brick leads to the decrease of the bulk density,the strength and the cold wear resistance;(3)the cross-distributed columnar mullite in the matrix can effectively improve the hot modulus of rupture and the thermal shock resistance of the specimens;(4)considering comprehensively,the andalusite addition shall not exceed 18%.
