This paper summarizes the selected results of an extensive investigation of application of two methods （hydrothermal and mechanochemical） assisted by calcination for synthesizing belite cement from reactive mixtures...This paper summarizes the selected results of an extensive investigation of application of two methods （hydrothermal and mechanochemical） assisted by calcination for synthesizing belite cement from reactive mixtures （CaO/SiO2 molar ratio of 2） consisting of various waste kinds from fluidized brown coal combustion in Slovakian power plant and CaO addition. Based on XRD diffraction patterns and infrared spectra ofpre-treatment products, the formation of the new profiles corresponding to CSH phases with low degree of ordering as belite precursors after hydrothermal treatment as well as metastables calcium silicates and aluminosilicates in mechanosynthesized products was confirmed. Calcination of hydrothermally treated products led to transformation of CSH phases to wollastonite （CS）, belite and gehlenite phase, whereas creation oft^- and I^-C2S or wollastonite in milled reactive mixture took place. Differences in phase composition of products before and after calcination depend upon waste quality and precursor＇s synthesis conditions. Bottom ash isn＇t suitable as raw material for synthesizing belite phase because of high CaO content fixed in anhydrite form （44.1%）. Coal fly ash with low CaO content in anhydrite form （4.2%） and its mechanochemical or hydrothermal treatment in combination with subsequent heating offer opportunities for the utilization of coal fly ash as raw material for belite production.展开更多
In this paper, the results of an extensive investigation of hydrothermal pre-treatment for synthesizing belite phase from reactive mixtures （CaO/SiO2 molar ratio of 2） consisting of one waste kinds （bottom ash-BA o...In this paper, the results of an extensive investigation of hydrothermal pre-treatment for synthesizing belite phase from reactive mixtures （CaO/SiO2 molar ratio of 2） consisting of one waste kinds （bottom ash-BA or fly ash-FA） from fluidised brown coal combustion in Slovakian power plant and CaO （analytical grade reagent） addition are summarized. Changes in structure and phase composition of hydrothermally synthesized belite precursors and subsequent calcinated products were compared with those of starting mixtures. Based on XRD diffraction patterns, the formation of the new profiles corresponding to CSH phases with low degree of ordering as belite precursors after hydrothermal treatment was confirmed. Calcination of hydrotermally treated products at 900℃ led to transformation of CSH phases to wollastonite, belite and gehlenite phase. Differences in phase composition of products before and after calcination depend upon waste quality and precursor＇s synthesis conditions. Bottom ash isn＇t suitable as raw material for synthesizing belite phase because of high CaO content fixed in anhydrite form （44.1%）. Coal fly ash with low CaO content in anhydrite form （4.2%） and its hydrothermal treatment in combination with subsequent heating offer opportunities for the utilization of coal fly ash as raw material for belite production.展开更多
Recent developments and trends spinel ferrite nanomaterial synthesis are briefly of sol-gel auto-combustion method for discussed and critically analyzed. The analysis of various parameters of reaction which could be u...Recent developments and trends spinel ferrite nanomaterial synthesis are briefly of sol-gel auto-combustion method for discussed and critically analyzed. The analysis of various parameters of reaction which could be used for better understanding of synthesis process and control of microstructure and property of spinel ferrite nanopowder products was the main objective of this review article. Special attention was paid to variety of particle size and phase purity. For these purposes the correlation between complexant, oxygen balance and combustion process chemical additives, as well as heating mechanism and atmosphere, was established. These results are relevant from standpoints of both application and processing of ferrites.展开更多
Recently, with the increasing use of TEM technique in mineralogy, more and more space groups of high-temperature phases and low-temperature phases and the domain structures of phase transitional minerals have been det...Recently, with the increasing use of TEM technique in mineralogy, more and more space groups of high-temperature phases and low-temperature phases and the domain structures of phase transitional minerals have been determined. Therefore, on the basis of summarizing the numerous results of individual minerals, it is necessary to discuss the relationship between the types of space groups of two phases and the nature of展开更多
Basaltic columnar jointing is a protogenetic-tensile-cracking structure of basalt, which includes two tiers of polygonal (usually hexagonal) prisms with their thickness and length being different. The origin of column...Basaltic columnar jointing is a protogenetic-tensile-cracking structure of basalt, which includes two tiers of polygonal (usually hexagonal) prisms with their thickness and length being different. The origin of columnar jointing had been explained by the traditional hypothesis of cooling-contraction for a long time. In 1981, the hypothesis of double-diffusive convection, which is analogous to the theory of salt fingers in marine physics, was proposed by Kantha, and 'basalt fingers'—a new concept was adopted.展开更多
Most cosmic dusts possess distinctive surfacial textures. The investigation on these textures greatly contributes to the research of ablation for meteorite and the geneses of cosmic dusts.
Domain structures in mineral crystals could be categorized into three groups and several subgroups within each group, based on characteristics of domain structures and mechanisms causing domain structures: (ⅰ) domain...Domain structures in mineral crystals could be categorized into three groups and several subgroups within each group, based on characteristics of domain structures and mechanisms causing domain structures: (ⅰ) domain structures constituted by domains with the same (or identical) crystal structure and chemical composition, including anti-phase domain structures, twinning domain structures, inversion domain structures, and translationtwinning domain structures; (ⅱ) domain structures constituted by two or more than two kinds of domains with the same chemical composition but different crystal structures; and (ⅲ) domain structures constituted by two kinds of compositional and structural different domains, including exsolution-induced and polysomatic reaction-induced domain structures. Different types of domain structures may display different phenomena in their TEM images and SAED patterns, due to different crystallographic characteristics of different domain structures. The domain structures in minerals may affect physical properties, chemical composition, and thermodynamic properties of minerals, and can also indicate the evolution history of minerals.展开更多
文摘This paper summarizes the selected results of an extensive investigation of application of two methods （hydrothermal and mechanochemical） assisted by calcination for synthesizing belite cement from reactive mixtures （CaO/SiO2 molar ratio of 2） consisting of various waste kinds from fluidized brown coal combustion in Slovakian power plant and CaO addition. Based on XRD diffraction patterns and infrared spectra ofpre-treatment products, the formation of the new profiles corresponding to CSH phases with low degree of ordering as belite precursors after hydrothermal treatment as well as metastables calcium silicates and aluminosilicates in mechanosynthesized products was confirmed. Calcination of hydrothermally treated products led to transformation of CSH phases to wollastonite （CS）, belite and gehlenite phase, whereas creation oft^- and I^-C2S or wollastonite in milled reactive mixture took place. Differences in phase composition of products before and after calcination depend upon waste quality and precursor＇s synthesis conditions. Bottom ash isn＇t suitable as raw material for synthesizing belite phase because of high CaO content fixed in anhydrite form （44.1%）. Coal fly ash with low CaO content in anhydrite form （4.2%） and its mechanochemical or hydrothermal treatment in combination with subsequent heating offer opportunities for the utilization of coal fly ash as raw material for belite production.
文摘In this paper, the results of an extensive investigation of hydrothermal pre-treatment for synthesizing belite phase from reactive mixtures （CaO/SiO2 molar ratio of 2） consisting of one waste kinds （bottom ash-BA or fly ash-FA） from fluidised brown coal combustion in Slovakian power plant and CaO （analytical grade reagent） addition are summarized. Changes in structure and phase composition of hydrothermally synthesized belite precursors and subsequent calcinated products were compared with those of starting mixtures. Based on XRD diffraction patterns, the formation of the new profiles corresponding to CSH phases with low degree of ordering as belite precursors after hydrothermal treatment was confirmed. Calcination of hydrotermally treated products at 900℃ led to transformation of CSH phases to wollastonite, belite and gehlenite phase. Differences in phase composition of products before and after calcination depend upon waste quality and precursor＇s synthesis conditions. Bottom ash isn＇t suitable as raw material for synthesizing belite phase because of high CaO content fixed in anhydrite form （44.1%）. Coal fly ash with low CaO content in anhydrite form （4.2%） and its hydrothermal treatment in combination with subsequent heating offer opportunities for the utilization of coal fly ash as raw material for belite production.
文摘Recent developments and trends spinel ferrite nanomaterial synthesis are briefly of sol-gel auto-combustion method for discussed and critically analyzed. The analysis of various parameters of reaction which could be used for better understanding of synthesis process and control of microstructure and property of spinel ferrite nanopowder products was the main objective of this review article. Special attention was paid to variety of particle size and phase purity. For these purposes the correlation between complexant, oxygen balance and combustion process chemical additives, as well as heating mechanism and atmosphere, was established. These results are relevant from standpoints of both application and processing of ferrites.
基金Project supported by the National Natural Science Foundation of China
文摘Recently, with the increasing use of TEM technique in mineralogy, more and more space groups of high-temperature phases and low-temperature phases and the domain structures of phase transitional minerals have been determined. Therefore, on the basis of summarizing the numerous results of individual minerals, it is necessary to discuss the relationship between the types of space groups of two phases and the nature of
文摘Basaltic columnar jointing is a protogenetic-tensile-cracking structure of basalt, which includes two tiers of polygonal (usually hexagonal) prisms with their thickness and length being different. The origin of columnar jointing had been explained by the traditional hypothesis of cooling-contraction for a long time. In 1981, the hypothesis of double-diffusive convection, which is analogous to the theory of salt fingers in marine physics, was proposed by Kantha, and 'basalt fingers'—a new concept was adopted.
基金Project supported by the National Natural Science Foundation of China.
文摘Most cosmic dusts possess distinctive surfacial textures. The investigation on these textures greatly contributes to the research of ablation for meteorite and the geneses of cosmic dusts.
基金This research program was supported by the National Natural Science Foundation of China, and Laboratory of Solid State Microstructures of Nanjing University.
文摘Domain structures in mineral crystals could be categorized into three groups and several subgroups within each group, based on characteristics of domain structures and mechanisms causing domain structures: (ⅰ) domain structures constituted by domains with the same (or identical) crystal structure and chemical composition, including anti-phase domain structures, twinning domain structures, inversion domain structures, and translationtwinning domain structures; (ⅱ) domain structures constituted by two or more than two kinds of domains with the same chemical composition but different crystal structures; and (ⅲ) domain structures constituted by two kinds of compositional and structural different domains, including exsolution-induced and polysomatic reaction-induced domain structures. Different types of domain structures may display different phenomena in their TEM images and SAED patterns, due to different crystallographic characteristics of different domain structures. The domain structures in minerals may affect physical properties, chemical composition, and thermodynamic properties of minerals, and can also indicate the evolution history of minerals.
