The Experts below are selected from a list of 7110 Experts worldwide ranked by ideXlab platform
Patrick Wollants - One of the best experts on this subject based on the ideXlab platform.
-
chemical corrosion mechanisms of Magnesia chromite and chrome free refractory bricks by copper metal and anode slag
Journal of The European Ceramic Society, 2007Co-Authors: Veselin Petkov, Peter Tom Jones, Eddy Boydens, Bart Blanpain, Patrick WollantsAbstract:Abstract The penetration and corrosion resistance to copper and anode slag of six Magnesia–chromite and six chrome-free refractory brick types were tested using static finger tests at a typical copper-refining temperature (1300 °C). The microstructures of the as-delivered and tested refractory types were investigated by means of electron-probe micro-analysis (EPMA) and scanning electron microscopy (SEM) techniques. The results showed that the overall wear rate of the fingers was very low, with the exception of the alumina-based brick made of fused corundum and Magnesia–alumina spinel, and the Magnesia-based brick made of sintered Magnesia and zircon addition. In all refractory types new phases were formed as a result of slag-refractory interactions. Apart from the samples recovered from the copper zone of the latest generation of direct-bonded Magnesia–chromite bricks, all the rest were completely infiltrated by copper and slag components (copper oxide, iron oxide, alumina and silica). However, the amount of infiltrated liquid in the chrome-free types was higher than in the Magnesia–chromite bricks. Explanations are provided for the distinct infiltration behaviour. The results show that economically viable chrome-free refractory alternatives are still elusive for anode furnace linings.
-
chemical corrosion mechanisms of Magnesia chromite and chrome free refractory bricks by copper metal and anode slag
Journal of The European Ceramic Society, 2007Co-Authors: Veselin Petkov, Peter Tom Jones, Eddy Boydens, Bart Blanpain, Patrick WollantsAbstract:Abstract The penetration and corrosion resistance to copper and anode slag of six Magnesia–chromite and six chrome-free refractory brick types were tested using static finger tests at a typical copper-refining temperature (1300 °C). The microstructures of the as-delivered and tested refractory types were investigated by means of electron-probe micro-analysis (EPMA) and scanning electron microscopy (SEM) techniques. The results showed that the overall wear rate of the fingers was very low, with the exception of the alumina-based brick made of fused corundum and Magnesia–alumina spinel, and the Magnesia-based brick made of sintered Magnesia and zircon addition. In all refractory types new phases were formed as a result of slag-refractory interactions. Apart from the samples recovered from the copper zone of the latest generation of direct-bonded Magnesia–chromite bricks, all the rest were completely infiltrated by copper and slag components (copper oxide, iron oxide, alumina and silica). However, the amount of infiltrated liquid in the chrome-free types was higher than in the Magnesia–chromite bricks. Explanations are provided for the distinct infiltration behaviour. The results show that economically viable chrome-free refractory alternatives are still elusive for anode furnace linings.
Zhu Ding - One of the best experts on this subject based on the ideXlab platform.
-
cementing mechanism of potassium phosphate based magnesium phosphate cement
Ceramics International, 2012Co-Authors: Zhu Ding, Feng Xing, Biqin Dong, Ningxu HanAbstract:Magnesium phosphate cements (MPCs) are materials that belong to chemically bonded ceramic materials. They have a wide range of potential applications, due to their superior performance. In this paper, the reaction products and cementing mechanism of magnesium phosphate bonded cement based on the dead burned Magnesia and the mono-potassium phosphate (MPP) are investigated. Fine powder and grains of dead burned Magnesia were used to prepare pure cement paste and bonding cluster samples, respectively. The cement reaction products and their micro-morphology in the both different samples are examined. The microstructure of specimens is analyzed by SEM, TEM, XDR, and optical microscopy. Struvite of potassium (MgKPO4·6H2O) is observed in the reaction products. According to the analysis, it is found that struvite exists in both crystalline and amorphous form. There is also residual Magnesia in the hardened cement paste. By means of microscopy observation, it can be seen that reaction products form around the unreacted Magnesia and can develop into a continuum structure, which further produces the hardened paste. Struvite can grow up to form the more perfect crystal in a long term curing age, if large enough space is available during the hydration process.
-
study of potassium based magnesium phosphate cement
Advances in Cement Research, 2011Co-Authors: Feng Xing, Zhu DingAbstract:A novel magnesium phosphate cement made from Magnesia and potassium phosphate was studied. The objective of the study was to examine the basic characteristics and cementing mechanism of the cement. The effect of Magnesia content on setting time, temperature rise during initial reaction and strength development of the cement mortar were examined. The reaction products of cement with water, and cementing structure were also examined. The results show that the cement was rapid setting and had high early strength. With the increase of Magnesia content, the setting time of cement became shorter and the temperature rose higher during initial reaction. Compressive strength was also increased with increasing Magnesia content. The microstructure of the hardened cement was studied by X-ray diffraction and scanning electron microscopy–energy dispersive spectroscopy. The reaction product in the cement is magnesium potassium phosphate hexhydrate (MgKPO4·6H2O-MKP).
-
high early strength magnesium phosphate cement with fly ash
Aci Materials Journal, 2005Co-Authors: Zhu DingAbstract:To understand the mechanism of fly ash in a novel Magnesia phosphate cement (MPC), the microstructure and properties were investigated in the present study. Reference specimens without the incorporation of fly ash were also investigated for comparison purposes. The effect of fly ash content on the properties of MPC was studied with two dead burnt Magnesia materials with different MgO contents and fineness. The results demonstrated that fly ash does improve the bonding and compressive strength of MPC, even at very early ages. Fly ash content of 30 to 50% has the best improving effect on MPC, despite the two types of Magnesia. Due to the difference of MgO content and particle fineness of two dead burnt Magnesia materials, MPC mortars with finer Magnesia revealed higher compressive strength. The incorporation of fly ash does not retard the setting reaction of MPC, but it does reduce its total heat evolution. The hydrates and microstructure of MPC paste were examined by an x-ray diffractometer, scanning electron microscopy-energy dispersive x-ray analysis (SEM-EDX), and Fourier transform infrared (FTIR) spectroscopy. These techniques revealed that the products formed in MPC paste were crystal magnesium potassium phosphate hexahydrate and amorphous species. The particles of fly ash fill the voids of MPC paste and strongly bond together with hydrates of MPC. The microanalysis showed that the strengthening of fly ash to the cement might come from physical and chemical effects.
Veselin Petkov - One of the best experts on this subject based on the ideXlab platform.
-
chemical corrosion mechanisms of Magnesia chromite and chrome free refractory bricks by copper metal and anode slag
Journal of The European Ceramic Society, 2007Co-Authors: Veselin Petkov, Peter Tom Jones, Eddy Boydens, Bart Blanpain, Patrick WollantsAbstract:Abstract The penetration and corrosion resistance to copper and anode slag of six Magnesia–chromite and six chrome-free refractory brick types were tested using static finger tests at a typical copper-refining temperature (1300 °C). The microstructures of the as-delivered and tested refractory types were investigated by means of electron-probe micro-analysis (EPMA) and scanning electron microscopy (SEM) techniques. The results showed that the overall wear rate of the fingers was very low, with the exception of the alumina-based brick made of fused corundum and Magnesia–alumina spinel, and the Magnesia-based brick made of sintered Magnesia and zircon addition. In all refractory types new phases were formed as a result of slag-refractory interactions. Apart from the samples recovered from the copper zone of the latest generation of direct-bonded Magnesia–chromite bricks, all the rest were completely infiltrated by copper and slag components (copper oxide, iron oxide, alumina and silica). However, the amount of infiltrated liquid in the chrome-free types was higher than in the Magnesia–chromite bricks. Explanations are provided for the distinct infiltration behaviour. The results show that economically viable chrome-free refractory alternatives are still elusive for anode furnace linings.
-
chemical corrosion mechanisms of Magnesia chromite and chrome free refractory bricks by copper metal and anode slag
Journal of The European Ceramic Society, 2007Co-Authors: Veselin Petkov, Peter Tom Jones, Eddy Boydens, Bart Blanpain, Patrick WollantsAbstract:Abstract The penetration and corrosion resistance to copper and anode slag of six Magnesia–chromite and six chrome-free refractory brick types were tested using static finger tests at a typical copper-refining temperature (1300 °C). The microstructures of the as-delivered and tested refractory types were investigated by means of electron-probe micro-analysis (EPMA) and scanning electron microscopy (SEM) techniques. The results showed that the overall wear rate of the fingers was very low, with the exception of the alumina-based brick made of fused corundum and Magnesia–alumina spinel, and the Magnesia-based brick made of sintered Magnesia and zircon addition. In all refractory types new phases were formed as a result of slag-refractory interactions. Apart from the samples recovered from the copper zone of the latest generation of direct-bonded Magnesia–chromite bricks, all the rest were completely infiltrated by copper and slag components (copper oxide, iron oxide, alumina and silica). However, the amount of infiltrated liquid in the chrome-free types was higher than in the Magnesia–chromite bricks. Explanations are provided for the distinct infiltration behaviour. The results show that economically viable chrome-free refractory alternatives are still elusive for anode furnace linings.
Ningxu Han - One of the best experts on this subject based on the ideXlab platform.
-
cementing mechanism of potassium phosphate based magnesium phosphate cement
Ceramics International, 2012Co-Authors: Zhu Ding, Feng Xing, Biqin Dong, Ningxu HanAbstract:Magnesium phosphate cements (MPCs) are materials that belong to chemically bonded ceramic materials. They have a wide range of potential applications, due to their superior performance. In this paper, the reaction products and cementing mechanism of magnesium phosphate bonded cement based on the dead burned Magnesia and the mono-potassium phosphate (MPP) are investigated. Fine powder and grains of dead burned Magnesia were used to prepare pure cement paste and bonding cluster samples, respectively. The cement reaction products and their micro-morphology in the both different samples are examined. The microstructure of specimens is analyzed by SEM, TEM, XDR, and optical microscopy. Struvite of potassium (MgKPO4·6H2O) is observed in the reaction products. According to the analysis, it is found that struvite exists in both crystalline and amorphous form. There is also residual Magnesia in the hardened cement paste. By means of microscopy observation, it can be seen that reaction products form around the unreacted Magnesia and can develop into a continuum structure, which further produces the hardened paste. Struvite can grow up to form the more perfect crystal in a long term curing age, if large enough space is available during the hydration process.
Chi Sun Poon - One of the best experts on this subject based on the ideXlab platform.
-
mixture design and reaction sequence for recycling construction wood waste into rapid shaping Magnesia phosphate cement particleboard
Industrial & Engineering Chemistry Research, 2017Co-Authors: Lei Wang, Iris K M Yu, Daniel C W Tsang, Shuang Li, Chi Sun PoonAbstract:This study has elucidated the roles of hydration chemistry and reaction sequence of Magnesia–phosphate cement (MPC) in the upcycling of construction wood waste into rapid-shaping cement-bonded particleboards. The mineralogy and microstructure were evaluated using thermogravimetry, quantitative X-ray diffraction, scanning electron microscopy, and mercury intrusion porosimetry. The results showed that the Magnesia-to-phosphate (M/P) ratio controlled the formation of magnesium potassium phosphate hexahydrate (MgKPO4·6H2O, MKP) for strength development. Low M/P ratios gave ill-formed MKP, whereas high M/P ratios resulted in unreacted Magnesia. The optimal M/P ratio of 7 led to a much shorter setting time and greater compatibility with wood waste than for ordinary Portland cement. Wood waste can provide a platform for cement hydration and porosity for harboring crystalline MKP and also regulate water release to maintain a moderate MPC reaction. We also highlight the importance of reaction sequence for promotin...
-
Mixture Design and Reaction Sequence for Recycling Construction Wood Waste into Rapid-Shaping Magnesia–Phosphate Cement Particleboard
2017Co-Authors: Lei Wang, Daniel C W Tsang, Chi Sun PoonAbstract:This study has elucidated the roles of hydration chemistry and reaction sequence of Magnesia–phosphate cement (MPC) in the upcycling of construction wood waste into rapid-shaping cement-bonded particleboards. The mineralogy and microstructure were evaluated using thermogravimetry, quantitative X-ray diffraction, scanning electron microscopy, and mercury intrusion porosimetry. The results showed that the Magnesia-to-phosphate (M/P) ratio controlled the formation of magnesium potassium phosphate hexahydrate (MgKPO4·6H2O, MKP) for strength development. Low M/P ratios gave ill-formed MKP, whereas high M/P ratios resulted in unreacted Magnesia. The optimal M/P ratio of 7 led to a much shorter setting time and greater compatibility with wood waste than for ordinary Portland cement. Wood waste can provide a platform for cement hydration and porosity for harboring crystalline MKP and also regulate water release to maintain a moderate MPC reaction. We also highlight the importance of reaction sequence for promoting matrix homogeneity and MKP crystallinity. Our approach enables fast production of value-added construction products from wood waste
