During calcining the aluminum hydroxide according to the Bayer process in a rotary kiln,the process of incomplete conversion to alpha alumina by soft calcination leads to a special intermediate alumina product contain...During calcining the aluminum hydroxide according to the Bayer process in a rotary kiln,the process of incomplete conversion to alpha alumina by soft calcination leads to a special intermediate alumina product containing microcrystalline of primary crystal alpha alumina particles less than 0.4μm,and other alumina phases with finer microcrystalline of less than 0.2μm particles.This special alumina powder has similar properties to silica fume or clay,such as high surface area and reactivity,fast wetting,low water demand and high stick-ability.It can partially or completely replace silica fume and clay in dry gunning mixes.It works towards improving the high temperature resistance of the gunning material matrix as well as the corrosion resistance and service life of the gunning materials.The application results show that:the ladle cementfree alumina-magnesia dry gunning mix with this special alumina sub-micro powder,compared with traditional dry gunning materials,has lower rebound loss(<10%),better adhesion rate,higher corrosion resistance and peeling resistance;and it can replace the veneering casting repair to achieve the similar performance.A further improvement goal is to replace the initial casting linings,thus this concept will give a new revolution to the monolithic steel ladles.展开更多
This study aimed to investigate the erosion behavior and mechanism of a newly developed 25Cr3Mo2WNiV steel with a chrome coating using promoted ignition combustion tests.The erosion threshold pressure and temperature ...This study aimed to investigate the erosion behavior and mechanism of a newly developed 25Cr3Mo2WNiV steel with a chrome coating using promoted ignition combustion tests.The erosion threshold pressure and temperature of the chrome-coated 25Cr3Mo2WNiV steel were determined to be 0.2 MPa and 254.3 K higher than those of traditional chrome-coated 30SiMn2MoV steel.Furthermore,Kirkendall voids and inter-diffusion between the Cr coating and matrix were first observed before ero-sion.The improved erosion resistance of the chrome-coated 25Cr3Mo2WNiV steel was attributed to the suppression of the Kirkendall effect,which minimized heat generation at the Cr/matrix interface by pre-venting oxygen diffusion and reducing oxygen affinity.展开更多
文摘During calcining the aluminum hydroxide according to the Bayer process in a rotary kiln,the process of incomplete conversion to alpha alumina by soft calcination leads to a special intermediate alumina product containing microcrystalline of primary crystal alpha alumina particles less than 0.4μm,and other alumina phases with finer microcrystalline of less than 0.2μm particles.This special alumina powder has similar properties to silica fume or clay,such as high surface area and reactivity,fast wetting,low water demand and high stick-ability.It can partially or completely replace silica fume and clay in dry gunning mixes.It works towards improving the high temperature resistance of the gunning material matrix as well as the corrosion resistance and service life of the gunning materials.The application results show that:the ladle cementfree alumina-magnesia dry gunning mix with this special alumina sub-micro powder,compared with traditional dry gunning materials,has lower rebound loss(<10%),better adhesion rate,higher corrosion resistance and peeling resistance;and it can replace the veneering casting repair to achieve the similar performance.A further improvement goal is to replace the initial casting linings,thus this concept will give a new revolution to the monolithic steel ladles.
基金Technology Fund of the Ministry of science and technology(No.2020-JCJQ-JJ-248)Fundamental Research Funds for the Central Universities(No.FRF-GF-20-21B)+1 种基金National Natural Science Foundation of China(No.52101072)The authors would like to express their gratitude for the experimental contributions and helpful suggestions from Dr.T.L.Sun.
文摘This study aimed to investigate the erosion behavior and mechanism of a newly developed 25Cr3Mo2WNiV steel with a chrome coating using promoted ignition combustion tests.The erosion threshold pressure and temperature of the chrome-coated 25Cr3Mo2WNiV steel were determined to be 0.2 MPa and 254.3 K higher than those of traditional chrome-coated 30SiMn2MoV steel.Furthermore,Kirkendall voids and inter-diffusion between the Cr coating and matrix were first observed before ero-sion.The improved erosion resistance of the chrome-coated 25Cr3Mo2WNiV steel was attributed to the suppression of the Kirkendall effect,which minimized heat generation at the Cr/matrix interface by pre-venting oxygen diffusion and reducing oxygen affinity.
