The production of traditional cementitious binders such as calcium-based Portland cement poses a serious challenge to the environment and society.Therefore,low-carbon,green and sustainable magnesium-based cementitious...The production of traditional cementitious binders such as calcium-based Portland cement poses a serious challenge to the environment and society.Therefore,low-carbon,green and sustainable magnesium-based cementitious materials are developed to replace fully or partly Portland cement and reduce the consumption of natural resources and CO_(2)emissions.Three interesting techniques,including reactive MgO-activated industrial solid wastes,MgO-based cement and carbonation of magnesium-bearing materials,are elucidated to point to the necessity for developing novel magnesium-based cementitious materials.In the coming future,the carbonation of magnesium-rich industrial solid wastes or its combination with reactive MgO for application in various construction sectors such as soft ground improvement and concrete fabrication would be a promising approach to generate high-value products based on industrial solid wastes.展开更多
The relative performance of coatings for furan resin sand moulds [P-toluol sulphonic acid(PTSA) as hardener] [FRS-PTSA moulds], was compared by analyzing the surface layer for degenerated graphite in Mg treated iron w...The relative performance of coatings for furan resin sand moulds [P-toluol sulphonic acid(PTSA) as hardener] [FRS-PTSA moulds], was compared by analyzing the surface layer for degenerated graphite in Mg treated iron with 0.020 wt.% to 0.054 wt.% Mgres. It was found that the iron nodularising potential(Mg, Ce, La content) and whether the mould coatings contained S, or were capable of desulphurizing were important factors. These moulds have S in the PTSA binder, which aggravates graphite degeneration in the surface layer, depending strongly on the Mgres with lower Mgres increasing the layer thickness. The application of a mould coating strongly influenced graphite deterioration in the surface layer of castings. It either promoted graphite degeneration to less compact morphologies when using S-bearing coatings, or conversely, limited the surface layer thickness using desulphurization type coatings. Independently of the S-source at the metal – mould interface, the presence of sulphur had an adverse effect on graphite quality at the surface of Mg-treated irons, but its negative effect could also reach the graphite phase within the casting section. If the coatings employed desulphurization materials, such as Mg O, or a mixture(Ca O + Mg O + Talc) or Mgbearing Fe Si, they protected the graphite shape, improving graphite nodularity, at the metal – mould interface, and so decreased the average layer thickness in FRS-PTSA moulds. Fe Si Mg was highly efficient in minimizing the casting skin by improving graphite nodularity. It is presumed that the Mg O or(Mg O + Ca O + Talc) based coatings acted to remove any S released by the mould media. The Mg-Fe Si coatings also reacted with S from the mould but additionally supplemented the Mg nodularising potential prior to solidification. This dual activity is achievable with coatings containing active magnesium derived from fine Mg-Fe Si materials.展开更多
Titanite is a widespread accessory mineral in metamorphic rocks. The united exchange Ti+O=(Al, Fe<sup>3+</sup>)+（OH, F） is now recognized as a common substitution in metamorphic titanite. Five theoretica...Titanite is a widespread accessory mineral in metamorphic rocks. The united exchange Ti+O=(Al, Fe<sup>3+</sup>)+（OH, F） is now recognized as a common substitution in metamorphic titanite. Five theoretical titanite end-members were recognized by Smith: CaTiSiO<sub>4</sub>O （oxy-titano-titanite）, CaAlSiO<sub>4</sub>OH （hydroxy-alumino-titanite）, CaAlSiO<sub>4</sub>F （flour-aluminotitanite）, CaFeSiO<sub>4</sub>OH （hydroxy-ferri-titanite） and CaFeSiO<sub>4</sub>F （flour-ferri-titanite）.展开更多
文摘The production of traditional cementitious binders such as calcium-based Portland cement poses a serious challenge to the environment and society.Therefore,low-carbon,green and sustainable magnesium-based cementitious materials are developed to replace fully or partly Portland cement and reduce the consumption of natural resources and CO_(2)emissions.Three interesting techniques,including reactive MgO-activated industrial solid wastes,MgO-based cement and carbonation of magnesium-bearing materials,are elucidated to point to the necessity for developing novel magnesium-based cementitious materials.In the coming future,the carbonation of magnesium-rich industrial solid wastes or its combination with reactive MgO for application in various construction sectors such as soft ground improvement and concrete fabrication would be a promising approach to generate high-value products based on industrial solid wastes.
基金funded by the Sectoral Operational Programme Human Resources Development 2007-2013 of the Romanian Ministry of Labour,Family and Social Protection through the Financial Agreement POSDRU/6/1.5/S/19
文摘The relative performance of coatings for furan resin sand moulds [P-toluol sulphonic acid(PTSA) as hardener] [FRS-PTSA moulds], was compared by analyzing the surface layer for degenerated graphite in Mg treated iron with 0.020 wt.% to 0.054 wt.% Mgres. It was found that the iron nodularising potential(Mg, Ce, La content) and whether the mould coatings contained S, or were capable of desulphurizing were important factors. These moulds have S in the PTSA binder, which aggravates graphite degeneration in the surface layer, depending strongly on the Mgres with lower Mgres increasing the layer thickness. The application of a mould coating strongly influenced graphite deterioration in the surface layer of castings. It either promoted graphite degeneration to less compact morphologies when using S-bearing coatings, or conversely, limited the surface layer thickness using desulphurization type coatings. Independently of the S-source at the metal – mould interface, the presence of sulphur had an adverse effect on graphite quality at the surface of Mg-treated irons, but its negative effect could also reach the graphite phase within the casting section. If the coatings employed desulphurization materials, such as Mg O, or a mixture(Ca O + Mg O + Talc) or Mgbearing Fe Si, they protected the graphite shape, improving graphite nodularity, at the metal – mould interface, and so decreased the average layer thickness in FRS-PTSA moulds. Fe Si Mg was highly efficient in minimizing the casting skin by improving graphite nodularity. It is presumed that the Mg O or(Mg O + Ca O + Talc) based coatings acted to remove any S released by the mould media. The Mg-Fe Si coatings also reacted with S from the mould but additionally supplemented the Mg nodularising potential prior to solidification. This dual activity is achievable with coatings containing active magnesium derived from fine Mg-Fe Si materials.
文摘Titanite is a widespread accessory mineral in metamorphic rocks. The united exchange Ti+O=(Al, Fe<sup>3+</sup>)+（OH, F） is now recognized as a common substitution in metamorphic titanite. Five theoretical titanite end-members were recognized by Smith: CaTiSiO<sub>4</sub>O （oxy-titano-titanite）, CaAlSiO<sub>4</sub>OH （hydroxy-alumino-titanite）, CaAlSiO<sub>4</sub>F （flour-aluminotitanite）, CaFeSiO<sub>4</sub>OH （hydroxy-ferri-titanite） and CaFeSiO<sub>4</sub>F （flour-ferri-titanite）.
