A reaction bonding technique and a method of layer coating were developed to fabricate porous SiC.The green body was prepared using 250.0μm SiC particles as the raw material,fineα-Al2O3 and SiC powders with mass rat...A reaction bonding technique and a method of layer coating were developed to fabricate porous SiC.The green body was prepared using 250.0μm SiC particles as the raw material,fineα-Al2O3 and SiC powders with mass ratio of 2.5:1as sintering additives,65.2μm graphite as the pore-forming agent and polyvinyl alcohol(PVA)as the binder.The micro powders were coated on the surface of coarse SiC particles.After sintering,fine SiC particles were oxidized to silica(SiO2)then transforming into cristobalite,which finally reacted withα-Al2O3 to produce mullite(3Al2O3·2SiO2).The results show that SiC particles are bonded by the mullite and oxidation-derived SiO2.The apparent porosity of the specimens decreases from 31.3%to 20.5%with the amount of micro powders increasing from 5 mass%to 20 mass%.The bending strength increases at the first stage and then decreases with the increase of fine powders,and the specimen with 10 mass%of fine powders shows relatively high bending strength of 23.5 MPa.展开更多
Ceramic membranes are effective to reduce PM2.5 emission when used for hot flue gas filtration.The properties of the sealing material play a decisive role infiltration efficiency.However,there are few studies on seali...Ceramic membranes are effective to reduce PM2.5 emission when used for hot flue gas filtration.The properties of the sealing material play a decisive role infiltration efficiency.However,there are few studies on sealing materials for hot flue gas filtration above 700 ℃.This investigation was performed to develop flexible sealing materials which can be used for a long time at high temperatures.In order to obtain sufficient mechanical strength and continuous flexibility,three kinds of binders were selected as coating binders.The sealing materials based on high silica fiber fabric and aluminum silicate fiber fabric were successfully prepared.The effect of aging on mechanical properties and microstructural characteristics of the composites subjected to coating had been investigated by XRD,SEM and EDS.The results show that waterborne polyurethane (WPU) is a suitable coating binder for the sealing materials,which can be used for a long time at 1 000 ℃ and 700 ℃,respectively,without significant decrease in strength.However,the other two binders,aluminum dihydrogen phosphate and aluminum chromium phosphate will weaken the flexibility,resulting in frangibility and reducing sealing performance.The developed composites possess required thermo-stability and desired mechanical strength as flexible sealing materials,indicating their strong application possibility in hot flue gas filtration.展开更多
The research findings of the project of tracing the origins of Chinese civilization substantiate China's million years of human history,10,000-plus years of cultural history,and 5,000-plus years of civilizational ...The research findings of the project of tracing the origins of Chinese civilization substantiate China's million years of human history,10,000-plus years of cultural history,and 5,000-plus years of civilizational history.Cities and capitals have been the foremost tangible embodiment throughout the formation and development of Chinese civilization.By examining the sites of ancient Chinese capitals and palaces,noting the transition from“shrines side by side with palaces”to“the imperial ancestral shrine on the left and the altar to the gods of earth and grain on the right,”and observing the evolution from“dual axis”to“central axis”in city planning,we can delve into the cultural genes that have shaped the development of Chinese civilization.Throughout history,China's first inhabitants and their descendants have forged strong traditions of ancestral identification,the unity and commensurability of family and state,and identification with the state.Characterized by powerful cohesiveness and inclusiveness,these traditions form the subtly ingrained and daily practiced cultural genes of Chinese civilization.They are the fundamental reasons behind the enduring continuity of Chinese civilization for over 5,000 years.展开更多
基金financially supported by National Key R&D Program of China (Grant No.: 2016YFB0601100)State Key Laboratory of Multi-phase Complex Systems (MPCS-2017- A-06)
文摘A reaction bonding technique and a method of layer coating were developed to fabricate porous SiC.The green body was prepared using 250.0μm SiC particles as the raw material,fineα-Al2O3 and SiC powders with mass ratio of 2.5:1as sintering additives,65.2μm graphite as the pore-forming agent and polyvinyl alcohol(PVA)as the binder.The micro powders were coated on the surface of coarse SiC particles.After sintering,fine SiC particles were oxidized to silica(SiO2)then transforming into cristobalite,which finally reacted withα-Al2O3 to produce mullite(3Al2O3·2SiO2).The results show that SiC particles are bonded by the mullite and oxidation-derived SiO2.The apparent porosity of the specimens decreases from 31.3%to 20.5%with the amount of micro powders increasing from 5 mass%to 20 mass%.The bending strength increases at the first stage and then decreases with the increase of fine powders,and the specimen with 10 mass%of fine powders shows relatively high bending strength of 23.5 MPa.
基金financially supported by National Key R&D Program of China(Grant No:2016YFB0601100)
文摘Ceramic membranes are effective to reduce PM2.5 emission when used for hot flue gas filtration.The properties of the sealing material play a decisive role infiltration efficiency.However,there are few studies on sealing materials for hot flue gas filtration above 700 ℃.This investigation was performed to develop flexible sealing materials which can be used for a long time at high temperatures.In order to obtain sufficient mechanical strength and continuous flexibility,three kinds of binders were selected as coating binders.The sealing materials based on high silica fiber fabric and aluminum silicate fiber fabric were successfully prepared.The effect of aging on mechanical properties and microstructural characteristics of the composites subjected to coating had been investigated by XRD,SEM and EDS.The results show that waterborne polyurethane (WPU) is a suitable coating binder for the sealing materials,which can be used for a long time at 1 000 ℃ and 700 ℃,respectively,without significant decrease in strength.However,the other two binders,aluminum dihydrogen phosphate and aluminum chromium phosphate will weaken the flexibility,resulting in frangibility and reducing sealing performance.The developed composites possess required thermo-stability and desired mechanical strength as flexible sealing materials,indicating their strong application possibility in hot flue gas filtration.
文摘The research findings of the project of tracing the origins of Chinese civilization substantiate China's million years of human history,10,000-plus years of cultural history,and 5,000-plus years of civilizational history.Cities and capitals have been the foremost tangible embodiment throughout the formation and development of Chinese civilization.By examining the sites of ancient Chinese capitals and palaces,noting the transition from“shrines side by side with palaces”to“the imperial ancestral shrine on the left and the altar to the gods of earth and grain on the right,”and observing the evolution from“dual axis”to“central axis”in city planning,we can delve into the cultural genes that have shaped the development of Chinese civilization.Throughout history,China's first inhabitants and their descendants have forged strong traditions of ancestral identification,the unity and commensurability of family and state,and identification with the state.Characterized by powerful cohesiveness and inclusiveness,these traditions form the subtly ingrained and daily practiced cultural genes of Chinese civilization.They are the fundamental reasons behind the enduring continuity of Chinese civilization for over 5,000 years.
