High alumina slag will cause severe corrosion at the interface of alumina refractory,and the wetting behavior of slag is a key factor influencing the corrosion resistance of refractory ceramics.The static magnetic fie...High alumina slag will cause severe corrosion at the interface of alumina refractory,and the wetting behavior of slag is a key factor influencing the corrosion resistance of refractory ceramics.The static magnetic field is a promising solution for improvement in the slag resistance of refractory.The wetting of alumina refractory ceramics with different basicities of high alumina slags under a weak static magnetic field was analyzed,given that a weak static magnetic field can affect the corrosion behavior of refractory ceramics.Taking slag S_(3) as an example,when there was an external static magnetic field of 1.0 mT at 1600 ℃,the thickness of calcium aluminate reaction layer at the interface decreased by 36.7%,the denting depth of interface decreased by 35.6%,and the apparent wetting angle increased by 20%.The living radicals and their formation path in oxide melts were verified by first-principles calculation combined with electron paramagnetic resonance spectroscopy analysis.The influence of the flux density of a weak static magnetic field on the wetting behavior of slags was also explored.The contact angle of the slags increased owing to the inhibitory effect of magnetic field on the radicalinvolved reaction at the interface of the slag and the alumina refractory ceramic.The relationships between the magnetic flux density,diffusion coefficient,slag microstructure(hyperfine coupling constant),and contact angle were established.This provides a theoretical basis for the field control of radical involved reactive wetting between inorganic oxide slags and solid oxide ceramics.展开更多
The dissolution of alumina-based refractory ceramics in CaO-Al2O3-SiO_(2)slag melts was performed based on the in-situ observation system of an ultra-high-temperature laser confocal microscope,and the effect of the Ca...The dissolution of alumina-based refractory ceramics in CaO-Al2O3-SiO_(2)slag melts was performed based on the in-situ observation system of an ultra-high-temperature laser confocal microscope,and the effect of the CaO/SiO_(2)slag mass ratio(C/S ratio)on the dissolution rate of alumina-based refractory ceramics was investigated.The results indicate that the dissolution rate increases with an increase of the C/S ratio and is mainly controlled by diffusion.During the early stage of dissolution,for all C/S ratios,the dissolution process conforms to the classical invariant interface approximation model.During the later stage of dissolution,when the C/S ratio is≥6,the dissolution process is significantly different from the model above because of the formation of a thick interfacial layer,which can be explained by dissolution kinetics.展开更多
Ordinary refractory ceramics are multi-phase materials,and their inhomogeneous microstructures induce the scatter of properties.The definition of a reasonable number of samples is important to obtain representative re...Ordinary refractory ceramics are multi-phase materials,and their inhomogeneous microstructures induce the scatter of properties.The definition of a reasonable number of samples is important to obtain representative results from experiments and simulations,and this reasonable number might be property or microstructure relevant.Stochastic discrete element(DE)simulations of cold crushing tests with homogeneous interface properties were performed.Three minimum DE size ranges were used to represent matrix variation at different levels.Statistical methods,i.e.,Kolmogorov–Smirnov(K–S)test,t-test,and correlation analysis,were utilized to study the influences of minimal number of samples on mechanical properties and crack density.It revealed that a relatively small number of samples are sufficient to obtain representative cold crushing strength(CCS)and Young’s modulus,whilst a large number of samples are favourable when the fracture energy and crack density under cold crushing conditions are of interest.The analysis also showed that the fracture energy under cold crushing condition generally correlates positively with CCS,and the static Young’s moduli determined from the stress–piston displacement curves with different definitions are divergent,caused by contact compliance and premature cracking.The data from the stress–strain curves recorded directly on the sample are required for the accurate static Young’s modulus calculation.展开更多
The strong covalent bonding characters of zirconium diboride（ Zr B2） and hafnium diboride（ Hf B2） with natural hexagonal Al B2-type crystal structure give them high melting points（ 〉 3 200 ℃）, high bending str...The strong covalent bonding characters of zirconium diboride（ Zr B2） and hafnium diboride（ Hf B2） with natural hexagonal Al B2-type crystal structure give them high melting points（ 〉 3 200 ℃）, high bending strength, high elastic modulus and high hardness.Zr B2- and Hf B2-based ceramics are promising candidates for the thermal protection components of propulsion systems,rocket nozzles,sharp leading edges and nose cones. This paper introduces the recent research progress on Zr B2- and Hf B2-based ceramics,including the synthesis methods of the boride powders,the sintering methods of the boride-based ceramics and their properties.The advantages of different synthesis methods and sintering methods are compared. The influence factors on the mechanical properties,oxidation resistance and thermal shock resistance are summarized.展开更多
As one of the most mature aluminum sheet continuous strip-casting processes,Hazelett strip-casting has been successfully industrially applied.This work introduced the key refractory materials for Hazelett strip-castin...As one of the most mature aluminum sheet continuous strip-casting processes,Hazelett strip-casting has been successfully industrially applied.This work introduced the key refractory materials for Hazelett strip-casting process,including large-scaled Al_2O_3 ceramic foam filters,wide-feed head boxes,monolithic strip-stream nozzles,and coatings on twin-belt.Besides,the localization of the refractory materials was discussed.展开更多
SiC whiskers were synthesized in a coke bed using a two-step heat treatment process.The temperature was held for 3 h at 1 200 ℃ before heating to 1 430 ℃ and holding for 3 h.The morphologies of SiC synthesized by th...SiC whiskers were synthesized in a coke bed using a two-step heat treatment process.The temperature was held for 3 h at 1 200 ℃ before heating to 1 430 ℃ and holding for 3 h.The morphologies of SiC synthesized by the two-step heat treatment method were much more different from those produced by direct heating to 1 430 ℃.SiC whiskers formed at 1 200 ℃ firstly and grew at1 430 ℃ to obtain a mean diameter about 326 nm,while the SiC grains with a size range from 0.70 to2.30 μm were obtained by direct heating to the target temperature of 1 430 ℃.This was explained by the different formation mechanisms.The result proposes a promising alternative technical process for whisker-reinforced ceramic/refractory composites in-situ during sintering.展开更多
Volume 50,Number 3,2016 Preparation and properties of infrared ceramics with high infrared emissivity/Yang Jinping,Wang Chunmei,Wei Hengyong,Chen Yang//Naihuo Cailiao.-2016,50（4）：241Abstract：This work aims at prep...Volume 50,Number 3,2016 Preparation and properties of infrared ceramics with high infrared emissivity/Yang Jinping,Wang Chunmei,Wei Hengyong,Chen Yang//Naihuo Cailiao.-2016,50（4）：241Abstract：This work aims at preparing ceramics with high infrared emissivity.Analytically pure Fe_2O_3,Co_2O_3,CuO,MnCO_3,Bi_2O_3,MgCO_3,talcum（≤0.1mm industrially pure）,kaolin clays,high temperature solid state synthesized spinel type ferrite.展开更多
基金supported by the National Natural Science Foundation of China(52272022)Key Program of the Natural Science Foundation of Hubei Province of China(2021CFA071).
文摘High alumina slag will cause severe corrosion at the interface of alumina refractory,and the wetting behavior of slag is a key factor influencing the corrosion resistance of refractory ceramics.The static magnetic field is a promising solution for improvement in the slag resistance of refractory.The wetting of alumina refractory ceramics with different basicities of high alumina slags under a weak static magnetic field was analyzed,given that a weak static magnetic field can affect the corrosion behavior of refractory ceramics.Taking slag S_(3) as an example,when there was an external static magnetic field of 1.0 mT at 1600 ℃,the thickness of calcium aluminate reaction layer at the interface decreased by 36.7%,the denting depth of interface decreased by 35.6%,and the apparent wetting angle increased by 20%.The living radicals and their formation path in oxide melts were verified by first-principles calculation combined with electron paramagnetic resonance spectroscopy analysis.The influence of the flux density of a weak static magnetic field on the wetting behavior of slags was also explored.The contact angle of the slags increased owing to the inhibitory effect of magnetic field on the radicalinvolved reaction at the interface of the slag and the alumina refractory ceramic.The relationships between the magnetic flux density,diffusion coefficient,slag microstructure(hyperfine coupling constant),and contact angle were established.This provides a theoretical basis for the field control of radical involved reactive wetting between inorganic oxide slags and solid oxide ceramics.
基金supported by the National Natural Science Foundation of China(52272022)the Special Project of Central Government for Local Science and Technology Development of Hubei Province(2019ZYYD076)the Innovation and Entrepreneurship Fund of Wuhan University of Science and Technology(D202202171045002669).
文摘The dissolution of alumina-based refractory ceramics in CaO-Al2O3-SiO_(2)slag melts was performed based on the in-situ observation system of an ultra-high-temperature laser confocal microscope,and the effect of the CaO/SiO_(2)slag mass ratio(C/S ratio)on the dissolution rate of alumina-based refractory ceramics was investigated.The results indicate that the dissolution rate increases with an increase of the C/S ratio and is mainly controlled by diffusion.During the early stage of dissolution,for all C/S ratios,the dissolution process conforms to the classical invariant interface approximation model.During the later stage of dissolution,when the C/S ratio is≥6,the dissolution process is significantly different from the model above because of the formation of a thick interfacial layer,which can be explained by dissolution kinetics.
文摘Ordinary refractory ceramics are multi-phase materials,and their inhomogeneous microstructures induce the scatter of properties.The definition of a reasonable number of samples is important to obtain representative results from experiments and simulations,and this reasonable number might be property or microstructure relevant.Stochastic discrete element(DE)simulations of cold crushing tests with homogeneous interface properties were performed.Three minimum DE size ranges were used to represent matrix variation at different levels.Statistical methods,i.e.,Kolmogorov–Smirnov(K–S)test,t-test,and correlation analysis,were utilized to study the influences of minimal number of samples on mechanical properties and crack density.It revealed that a relatively small number of samples are sufficient to obtain representative cold crushing strength(CCS)and Young’s modulus,whilst a large number of samples are favourable when the fracture energy and crack density under cold crushing conditions are of interest.The analysis also showed that the fracture energy under cold crushing condition generally correlates positively with CCS,and the static Young’s moduli determined from the stress–piston displacement curves with different definitions are divergent,caused by contact compliance and premature cracking.The data from the stress–strain curves recorded directly on the sample are required for the accurate static Young’s modulus calculation.
基金Financial supports from the National Natural Science Foundation of China ( No. 51272266 )the Science and Technology Commission of Shanghai ( No. 15ZR1445200 )the State Key Laboratory of High Performance Ceramics and Superfine Microstructure
文摘The strong covalent bonding characters of zirconium diboride（ Zr B2） and hafnium diboride（ Hf B2） with natural hexagonal Al B2-type crystal structure give them high melting points（ 〉 3 200 ℃）, high bending strength, high elastic modulus and high hardness.Zr B2- and Hf B2-based ceramics are promising candidates for the thermal protection components of propulsion systems,rocket nozzles,sharp leading edges and nose cones. This paper introduces the recent research progress on Zr B2- and Hf B2-based ceramics,including the synthesis methods of the boride powders,the sintering methods of the boride-based ceramics and their properties.The advantages of different synthesis methods and sintering methods are compared. The influence factors on the mechanical properties,oxidation resistance and thermal shock resistance are summarized.
文摘As one of the most mature aluminum sheet continuous strip-casting processes,Hazelett strip-casting has been successfully industrially applied.This work introduced the key refractory materials for Hazelett strip-casting process,including large-scaled Al_2O_3 ceramic foam filters,wide-feed head boxes,monolithic strip-stream nozzles,and coatings on twin-belt.Besides,the localization of the refractory materials was discussed.
基金supported by the 973 Program Earlier Research Project,under Grant No.2014CB660802
文摘SiC whiskers were synthesized in a coke bed using a two-step heat treatment process.The temperature was held for 3 h at 1 200 ℃ before heating to 1 430 ℃ and holding for 3 h.The morphologies of SiC synthesized by the two-step heat treatment method were much more different from those produced by direct heating to 1 430 ℃.SiC whiskers formed at 1 200 ℃ firstly and grew at1 430 ℃ to obtain a mean diameter about 326 nm,while the SiC grains with a size range from 0.70 to2.30 μm were obtained by direct heating to the target temperature of 1 430 ℃.This was explained by the different formation mechanisms.The result proposes a promising alternative technical process for whisker-reinforced ceramic/refractory composites in-situ during sintering.
文摘Volume 50,Number 3,2016 Preparation and properties of infrared ceramics with high infrared emissivity/Yang Jinping,Wang Chunmei,Wei Hengyong,Chen Yang//Naihuo Cailiao.-2016,50（4）：241Abstract：This work aims at preparing ceramics with high infrared emissivity.Analytically pure Fe_2O_3,Co_2O_3,CuO,MnCO_3,Bi_2O_3,MgCO_3,talcum（≤0.1mm industrially pure）,kaolin clays,high temperature solid state synthesized spinel type ferrite.
