The Si_(3)N_(4)-bonded silicon carbide(SiC)bricks in the sloped zone of dry quenching coke ovens support the weight of upper refractory materials and equipment.These bricks endure frequent temperature fluctuations and...The Si_(3)N_(4)-bonded silicon carbide(SiC)bricks in the sloped zone of dry quenching coke ovens support the weight of upper refractory materials and equipment.These bricks endure frequent temperature fluctuations and intense abrasion from coke dust,demanding extremely high performance.After three years of service,an analysis of the Si_(3)N_(4)-bonded SiC bricks revealed that oxidation,which reduces thermal shock resistance,is the primary cause of degradation.In the unused Si_(3)N_(4)-bonded SiC bricks,short columnar β-Si_(3)N_(4) forms an interwoven network around SiC particles and contains a small amount of plate-like Si_(2)N_(2)O.Under the complex N_(2)(84.42 vol.%)-CO_(2)(10.44 vol.%)-CO(4.43 vol.%)-H_(2)(0.56 vol.%)-O_(2)(0.15 vol.%)atmosphere in the dry quenching coke oven,O_(2)(0.15 vol.%)exhibits a stronger oxidizing effect than CO_(2)(10.44 vol.%)and CO(4.43 vol.%),making it the primary oxidizing agent.The short columnarβ-Si_(3)N_(4) is more susceptible to oxidation than the particulate SiC.Based on thermodynamic and kinetic analyses,the chemical stability of the phases in Si_(3)N_(4)-bonded SiC bricks ranks from strongest to weakest as follows:Si_(2)N_(2)O,SiC,Si_(3)N_(4).Future development of Si_(2)N_(2)O-bonded SiC bricks could improve the longevity of refractory materials in the sloped zone of dry quenching coke ovens.展开更多
Transition metal oxides(TMOs),thanks to their elevated theoretical capacitance and pseudocapacitive properties,are of particular interest in exploring the advanced supercapacitor electrode materials.The present work r...Transition metal oxides(TMOs),thanks to their elevated theoretical capacitance and pseudocapacitive properties,are of particular interest in exploring the advanced supercapacitor electrode materials.The present work reports the rapid laser-assisted synthesis of SiC@-Fe_(2)O_(3-x)anode materials with engineered oxygen vacancies in seconds,which improve the charge transport,redox activity,and structural stability,thus facilitating a substantial enhancement in electrochemical performance.As a result,the resultant SiC@Fe_(2)O_(3-x)nanowires exhibit excellent performances with an areal capacitance of 1082.16 at 5 mA cm^(-2),and retain 86.7%capacitance over 10,000 cycles.Furthermore,the assembled asymmetric supercapacitors(ASC),employing SiC@Fe_(2)O_(3-x)as the negative electrode and Ni(OH)2as the positive electrode,delivers a 1.5 V operating voltage,an energy density of 197μWh cm^(-2),and 80.6%capacitance retention after 14,000cycles,representing their promise toward the applications in next-generation energy storage materials.展开更多
Monolithic catalysts have been widely investigated for CO_(2) methanation due to their fast mass and heat transfer rate,but the effect of the interaction between the catalyst layer and the monolithic support has been ...Monolithic catalysts have been widely investigated for CO_(2) methanation due to their fast mass and heat transfer rate,but the effect of the interaction between the catalyst layer and the monolithic support has been little studied.In this work,Ni/Al_(2)O_(3)/SiC monolithic catalysts,Ni/Al_(2)O_(3) powder catalysts and Ni/Al_(2)O_(3)/SiC-M catalysts were prepared to explore the effect of Si-Al interaction between the catalyst layer and SiC ceramic for CO_(2) methanation performance.Ni/Al_(2)O_(3)/SiC exhibited a CO_(2) conversion of 53% and a CH_(4) specific reaction rate of 0.05 m mol·g^(-1)·s^(-1) under conditions of 0.1 M Pa,4 00℃,and a WHSV of 60000 ml·g^(-1)·h^(-1).The CO_(2) conversion raised by 0.15-fold and the CH_(4) specific reaction rate raised by 0.25-fold compared to Ni/Al_(2)O_(3) with the same catalyst content.SEM,XRD,Raman,and other characterization results revealed that the formation of Si-Al interaction between the catalyst layer and SiC ceramic could weaken the interaction between Ni and Al_(2)O_(3),thereby improving the catalytic activity of Ni/Al_(2)O_(3)/SiC catalyst.However,the Si-Al interaction was further strengthened during the hightemperature reaction process,which significantly weakened the interaction between Ni and Al_(2)O_(3),thereby leading to a decline in the catalytic performance of Ni/Al_(2)O_(3)/SiC catalyst during an 80-h stability test.This study provides valuable insights for future research and development of monolithic catalysts.展开更多
Ti3SiC2-reintbrced Ag-maJxix composites are expected to serve as eleclrical contacts. In this study, the wettability of Ag on a Ti3SiC2 subslxate was measured by the sessile drop melkod. The Ag-Ti3SiC2 composites were...Ti3SiC2-reintbrced Ag-maJxix composites are expected to serve as eleclrical contacts. In this study, the wettability of Ag on a Ti3SiC2 subslxate was measured by the sessile drop melkod. The Ag-Ti3SiC2 composites were prepared from Ag mad Ti3SiC2 powder mix- tures by pressureless sintering. The effects of compacting pressure （100-800 MPa）, sintering temperature （850-950~C）, mad soaking time （0.5-2 h） on the microslxucture mad properties of the Ag-Ti3SiC2 composites were investigated. The experimental results indicated that Ti3SiC2 paxticulates were uniformly distxibuted in flae Ag matrix, wiflaout reactions at the interthces between flae two phases. The prepared Ag-10wt%Ti3SiC2 had a relative density of 95% mad an electrical resistivity of 2.76 x 10 3 m~）＇cm when compacted at 800 MPa mad sintered at 950~C for 1 h. The incorporation of Ti3SiC2 into Ag was found to improve its hardness without substantially compromising its electrical conductivity; INs behavior was attxibuted to the combination of ceramic and metallic properties of the Ti3SiC2 reinforcement, suggesting its potential application in electrical contacts.展开更多
基金support from the National Natural Science Foundation of China(52172023 and 52302027).
文摘The Si_(3)N_(4)-bonded silicon carbide(SiC)bricks in the sloped zone of dry quenching coke ovens support the weight of upper refractory materials and equipment.These bricks endure frequent temperature fluctuations and intense abrasion from coke dust,demanding extremely high performance.After three years of service,an analysis of the Si_(3)N_(4)-bonded SiC bricks revealed that oxidation,which reduces thermal shock resistance,is the primary cause of degradation.In the unused Si_(3)N_(4)-bonded SiC bricks,short columnar β-Si_(3)N_(4) forms an interwoven network around SiC particles and contains a small amount of plate-like Si_(2)N_(2)O.Under the complex N_(2)(84.42 vol.%)-CO_(2)(10.44 vol.%)-CO(4.43 vol.%)-H_(2)(0.56 vol.%)-O_(2)(0.15 vol.%)atmosphere in the dry quenching coke oven,O_(2)(0.15 vol.%)exhibits a stronger oxidizing effect than CO_(2)(10.44 vol.%)and CO(4.43 vol.%),making it the primary oxidizing agent.The short columnarβ-Si_(3)N_(4) is more susceptible to oxidation than the particulate SiC.Based on thermodynamic and kinetic analyses,the chemical stability of the phases in Si_(3)N_(4)-bonded SiC bricks ranks from strongest to weakest as follows:Si_(2)N_(2)O,SiC,Si_(3)N_(4).Future development of Si_(2)N_(2)O-bonded SiC bricks could improve the longevity of refractory materials in the sloped zone of dry quenching coke ovens.
基金financially supported by the National Natural Science Foundation of China(No.52372063)China Postdoctoral Science Foundation(No.2023M730391)
文摘Transition metal oxides(TMOs),thanks to their elevated theoretical capacitance and pseudocapacitive properties,are of particular interest in exploring the advanced supercapacitor electrode materials.The present work reports the rapid laser-assisted synthesis of SiC@-Fe_(2)O_(3-x)anode materials with engineered oxygen vacancies in seconds,which improve the charge transport,redox activity,and structural stability,thus facilitating a substantial enhancement in electrochemical performance.As a result,the resultant SiC@Fe_(2)O_(3-x)nanowires exhibit excellent performances with an areal capacitance of 1082.16 at 5 mA cm^(-2),and retain 86.7%capacitance over 10,000 cycles.Furthermore,the assembled asymmetric supercapacitors(ASC),employing SiC@Fe_(2)O_(3-x)as the negative electrode and Ni(OH)2as the positive electrode,delivers a 1.5 V operating voltage,an energy density of 197μWh cm^(-2),and 80.6%capacitance retention after 14,000cycles,representing their promise toward the applications in next-generation energy storage materials.
基金the National Natural Science Foundation of China (22325804 and 22308148)the Natural Science Foundation of Jiangsu Province (BK20230344)the Natural Science Research Project of Jiangsu University (22KJB610001)。
文摘Monolithic catalysts have been widely investigated for CO_(2) methanation due to their fast mass and heat transfer rate,but the effect of the interaction between the catalyst layer and the monolithic support has been little studied.In this work,Ni/Al_(2)O_(3)/SiC monolithic catalysts,Ni/Al_(2)O_(3) powder catalysts and Ni/Al_(2)O_(3)/SiC-M catalysts were prepared to explore the effect of Si-Al interaction between the catalyst layer and SiC ceramic for CO_(2) methanation performance.Ni/Al_(2)O_(3)/SiC exhibited a CO_(2) conversion of 53% and a CH_(4) specific reaction rate of 0.05 m mol·g^(-1)·s^(-1) under conditions of 0.1 M Pa,4 00℃,and a WHSV of 60000 ml·g^(-1)·h^(-1).The CO_(2) conversion raised by 0.15-fold and the CH_(4) specific reaction rate raised by 0.25-fold compared to Ni/Al_(2)O_(3) with the same catalyst content.SEM,XRD,Raman,and other characterization results revealed that the formation of Si-Al interaction between the catalyst layer and SiC ceramic could weaken the interaction between Ni and Al_(2)O_(3),thereby improving the catalytic activity of Ni/Al_(2)O_(3)/SiC catalyst.However,the Si-Al interaction was further strengthened during the hightemperature reaction process,which significantly weakened the interaction between Ni and Al_(2)O_(3),thereby leading to a decline in the catalytic performance of Ni/Al_(2)O_(3)/SiC catalyst during an 80-h stability test.This study provides valuable insights for future research and development of monolithic catalysts.
基金financially supported by the National Natural Science Foundation of China(Nos.51731004,51671054,and 51501038)“the Fundamental Research Funds for the Central Universities”in China
文摘Ti3SiC2-reintbrced Ag-maJxix composites are expected to serve as eleclrical contacts. In this study, the wettability of Ag on a Ti3SiC2 subslxate was measured by the sessile drop melkod. The Ag-Ti3SiC2 composites were prepared from Ag mad Ti3SiC2 powder mix- tures by pressureless sintering. The effects of compacting pressure （100-800 MPa）, sintering temperature （850-950~C）, mad soaking time （0.5-2 h） on the microslxucture mad properties of the Ag-Ti3SiC2 composites were investigated. The experimental results indicated that Ti3SiC2 paxticulates were uniformly distxibuted in flae Ag matrix, wiflaout reactions at the interthces between flae two phases. The prepared Ag-10wt%Ti3SiC2 had a relative density of 95% mad an electrical resistivity of 2.76 x 10 3 m~）＇cm when compacted at 800 MPa mad sintered at 950~C for 1 h. The incorporation of Ti3SiC2 into Ag was found to improve its hardness without substantially compromising its electrical conductivity; INs behavior was attxibuted to the combination of ceramic and metallic properties of the Ti3SiC2 reinforcement, suggesting its potential application in electrical contacts.
