Alumina-based foam ceramic filters were fabricated by using alumina,SiC,magnesia powder as major materials.It has been found that this ceramic filter has a uniform macrostructure for filtering molten metals.The influe...Alumina-based foam ceramic filters were fabricated by using alumina,SiC,magnesia powder as major materials.It has been found that this ceramic filter has a uniform macrostructure for filtering molten metals.The influences of SiC and magnesia content,the sintering temperatures on ceramic properties were discussed.Alumina-based foam ceramic filters containing 2.2 mass% magnesia and 7.6 mass% SiC has a compressive strength of 1.36 MPa and a thermal shock resistance of 5 times.Its main phases after 1 hour sintering at 1 500℃ consist of alumina,silicon carbide,spinel and mullite.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
The fracture toughness and fracture work of A12O3/SiC prismatic ceramic composites was evaluated in this paper, which showed the fracture energy was improved greatly. Based on the observation 'for crack propagat...The fracture toughness and fracture work of A12O3/SiC prismatic ceramic composites was evaluated in this paper, which showed the fracture energy was improved greatly. Based on the observation 'for crack propagation and fracture morphology, the fracture behavior of the prismatic composites was analyzed. In the bending test, the composites displayed a non-catastrophic behavior and a graceful failure with reasonable load-carrying capability.展开更多
The performance of supported catalysts is significantly affected by the dispersion degree of the active components on the support.In this study,citric acid(CA)was used as a modifier to prepare Al_(2)O_(3)supported Mn-...The performance of supported catalysts is significantly affected by the dispersion degree of the active components on the support.In this study,citric acid(CA)was used as a modifier to prepare Al_(2)O_(3)supported Mn-Ce oxides(Mn-Ce/CA-Al_(2)O_(3))by the impregnation-calcination method.The characterization results showed that adding citric acid enhanced the dispersion of Mn-Ce oxides on the support,rendering Mn-Ce/CA-Al_(2)O_(3)with a larger specific surface area and abundant surface hydroxyl groups,thereby providing more reaction sites for catalytic ozonation.The Mn-Ce/CA-Al_(2)O_(3)exhibited excellent catalytic ozonation performance in degrading Reactive Black 5(RB5)dye.It achieved nearly complete decolorization of RB5 within 60 min,with a COD removal efficiency of 60%,which was superior to the sole ozonation(30%).Furthermore,the Mn-Ce/CA-Al_(2)O_(3)system demonstrated significant degradation of RB5 over a wide pH range of 3e11.Based on the XPS and EPR analysis results,a preliminary mechanism of catalytic ozonation over the Mn-Ce/CA-Al_(2)O_(3)was proposed.The redox cycle of Mn^(3+)/Mn^(4+)and Ce^(3+)/Ce^(4+)effectively accelerated the electron transfer process,thus promoting the generation of reactive oxygen species(ROS)and improving the degradation of RB5.Meanwhile,the Mn-Ce/CA-Al_(2)O_(3)exhibited superior catalytic stability and effective treatment capabilities for real dye wastewater.展开更多
Alumina-based composites containing 0-15wt% Ni metallic phase were produced by hot press-sintering Ni-coated alumina powders. The Ni-coated alumina powders were prepared by the aqueous heterogeneous precipitation of a...Alumina-based composites containing 0-15wt% Ni metallic phase were produced by hot press-sintering Ni-coated alumina powders. The Ni-coated alumina powders were prepared by the aqueous heterogeneous precipitation of alumina micro-powders and nickel sulfate salt followed by reduction process. The microstructural features and dispersion of Ni phase in Ni-coated alumina powders and the subsequent alumina-Ni cermets were investigated using scanning electron microscope （SEM）, X-ray diffractometer （XRD）, and transmission electron microscope （TEM）. The relative density of the hot press-sintered composites was measured with the Archimedes＇ method while the fracture strength and the fracture toughness were defined with the three-point bending method and the micro-indentation fracture method. In the formation of alumina-Ni cermets from sintered Ni-coated alumina powders, Ni phase to some extent limits the densification rate and stifles the coarsening and growing process of alumina grains. The Ni phase is found to be located at the interfaces and the triple-joint junctions of alumina grains which results into alteration of the fracture mode of alumina and its increased fracture strength and fracture toughness if compared with monolithic alumina.展开更多
基金The project is supported by National Natural Science Foundation of China:50334030PhD Fund of Liaoning Province:20041010.
文摘Alumina-based foam ceramic filters were fabricated by using alumina,SiC,magnesia powder as major materials.It has been found that this ceramic filter has a uniform macrostructure for filtering molten metals.The influences of SiC and magnesia content,the sintering temperatures on ceramic properties were discussed.Alumina-based foam ceramic filters containing 2.2 mass% magnesia and 7.6 mass% SiC has a compressive strength of 1.36 MPa and a thermal shock resistance of 5 times.Its main phases after 1 hour sintering at 1 500℃ consist of alumina,silicon carbide,spinel and mullite.
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The fracture toughness and fracture work of A12O3/SiC prismatic ceramic composites was evaluated in this paper, which showed the fracture energy was improved greatly. Based on the observation 'for crack propagation and fracture morphology, the fracture behavior of the prismatic composites was analyzed. In the bending test, the composites displayed a non-catastrophic behavior and a graceful failure with reasonable load-carrying capability.
基金supported by the National Key Research and Development Program(2023YFC3207003)the National Natural Science Foundation of China(51878448).
文摘The performance of supported catalysts is significantly affected by the dispersion degree of the active components on the support.In this study,citric acid(CA)was used as a modifier to prepare Al_(2)O_(3)supported Mn-Ce oxides(Mn-Ce/CA-Al_(2)O_(3))by the impregnation-calcination method.The characterization results showed that adding citric acid enhanced the dispersion of Mn-Ce oxides on the support,rendering Mn-Ce/CA-Al_(2)O_(3)with a larger specific surface area and abundant surface hydroxyl groups,thereby providing more reaction sites for catalytic ozonation.The Mn-Ce/CA-Al_(2)O_(3)exhibited excellent catalytic ozonation performance in degrading Reactive Black 5(RB5)dye.It achieved nearly complete decolorization of RB5 within 60 min,with a COD removal efficiency of 60%,which was superior to the sole ozonation(30%).Furthermore,the Mn-Ce/CA-Al_(2)O_(3)system demonstrated significant degradation of RB5 over a wide pH range of 3e11.Based on the XPS and EPR analysis results,a preliminary mechanism of catalytic ozonation over the Mn-Ce/CA-Al_(2)O_(3)was proposed.The redox cycle of Mn^(3+)/Mn^(4+)and Ce^(3+)/Ce^(4+)effectively accelerated the electron transfer process,thus promoting the generation of reactive oxygen species(ROS)and improving the degradation of RB5.Meanwhile,the Mn-Ce/CA-Al_(2)O_(3)exhibited superior catalytic stability and effective treatment capabilities for real dye wastewater.
基金Innovation Foundation of Jiangsu University(04CX01)
文摘Alumina-based composites containing 0-15wt% Ni metallic phase were produced by hot press-sintering Ni-coated alumina powders. The Ni-coated alumina powders were prepared by the aqueous heterogeneous precipitation of alumina micro-powders and nickel sulfate salt followed by reduction process. The microstructural features and dispersion of Ni phase in Ni-coated alumina powders and the subsequent alumina-Ni cermets were investigated using scanning electron microscope （SEM）, X-ray diffractometer （XRD）, and transmission electron microscope （TEM）. The relative density of the hot press-sintered composites was measured with the Archimedes＇ method while the fracture strength and the fracture toughness were defined with the three-point bending method and the micro-indentation fracture method. In the formation of alumina-Ni cermets from sintered Ni-coated alumina powders, Ni phase to some extent limits the densification rate and stifles the coarsening and growing process of alumina grains. The Ni phase is found to be located at the interfaces and the triple-joint junctions of alumina grains which results into alteration of the fracture mode of alumina and its increased fracture strength and fracture toughness if compared with monolithic alumina.
