Cerium carbonate powders were produced in a submerged circulation impinging stream reactor (SCISR) from Ce(NO3)3· 6H2O. NH4HCO3 was used as a precipitant in the reaction. Cerium carbonate powders were roasted...Cerium carbonate powders were produced in a submerged circulation impinging stream reactor (SCISR) from Ce(NO3)3· 6H2O. NH4HCO3 was used as a precipitant in the reaction. Cerium carbonate powders were roasted to produce ultra-fine cerium dioxide (CeO2) powders. The optimal conditions of such production process were obtained by orthogonal and one-factor experiments. The results showed that ultra-fine and narrowly distributed cerium carbonate powders were produced under the optimal flowing conditions. The concentrations of Ce(NO3)3 and NH4HCO3 solutions were 02,5 and 0.3 mol · L^-1, respectively. The concentration of PEG4000 added in these two solutions was 4 g · L^-1. The stirring ratio, reaction temperature, feeding time, solution pH, reaction time and digestion time were 900 r · min^- 1,80 ℃, 20 min, 5 - 6, 5 min and 1 h, respectively. The final product, CeO2 powders, was obtained by roasting the produced cerium carbonate in air for 3 h at 500 ℃. The finally produced CeO2 powders were torispherical particles with a narrow size distribution of 0.8 -2.5 μm. The crystal structure of CeO2 powders belonged to cubic crystal system and its space point 5 group was OH^5-FM3M. Under optimal conditions, powders produced by SCISR were finer and more narrowly distributed than that by Stirred Tank Reactor (STR).展开更多
Dynamic rheological characteristics of polypropylene (PP) filled with ultra-fine full-vulcanized powdered rubber (UFPR) composed of styrene-butadiene copolymer were studied through dynamic rheological measurements on ...Dynamic rheological characteristics of polypropylene (PP) filled with ultra-fine full-vulcanized powdered rubber (UFPR) composed of styrene-butadiene copolymer were studied through dynamic rheological measurements on an Advanced Rheometric Expansion System (ARES). A specific viscoelastic phenomenon, i.e. 'the second plateau', appeared at low frequencies, and exhibits a certain dependence on the amount of rubber particles and the dispersion state in the matrix. This phenomenon is attributed to the formation of aggregation structure of rubber particles. The analyses of Cole-Cole diagrams of the dynamic viscoelastic functions suggest that the heterogeneity of the composites is enhanced on increasing both particle content and temperature.展开更多
The ultra-fine chromic oxide powder was prepared by a novel gas-solid reduction reaction.Na2CrO4 was firstly reduced with hydrogen at 400-600 ℃.The obtained reduction products,mainly the mixture of NaCrO2 and sodium ...The ultra-fine chromic oxide powder was prepared by a novel gas-solid reduction reaction.Na2CrO4 was firstly reduced with hydrogen at 400-600 ℃.The obtained reduction products,mainly the mixture of NaCrO2 and sodium hydroxide(NaOH),were converted into chromic oxide through hydrolysis followed by calcination.The obtained chromic oxide product was characterized by powder X-ray diffraction(XRD) and SEM.The results show that the hydrolysis process of sodium chromite is the key step and lower reduction temperature helps intensify the hydrolysis process.展开更多
In this study, three kinds of modified ultra-fine ceramic powders marked A, B and C, which were prepared by each of three different modifiers mixing with a commercial SiC, were added to HT250 cast iron, respectively, ...In this study, three kinds of modified ultra-fine ceramic powders marked A, B and C, which were prepared by each of three different modifiers mixing with a commercial SiC, were added to HT250 cast iron, respectively, and the effects of the modified ultra-fine ceramic powders on microstructure, mechanical properties and wear resistance were studied. Metallographic examination, tensile test, scanning electron microscopy, and three-dimensional surface topography were applied to analyze and compare the samples containing modified powder with the original samples. The results showed that the most obvious modification effect among the powders was seen in the sample containing powder A, with the graphite and eutectic cells being refined, the tensile strength being increased by 36.9%, and the wear resistance being improved by 45.5% and 47.2% under loads of 150 N and 300 N, respectively. The improvements of mechanical properties and wear resistance in the HT250 cast iron with the modified ultra-fine ceramic powders were attributed to the synergistic effect of the grain refinement with the powder acting as a hard particle phase and the lubrication by the graphite.展开更多
Ultra-fine CeO_2-ZrO_2 mixed oxide was successfully synthesized by wet-solid phase mechanochemical processing, Ce_2(CO_3)_3·8H_2O, ZrOCl_2·xH_2O and ammonia were used as reactants. It is found that the cryst...Ultra-fine CeO_2-ZrO_2 mixed oxide was successfully synthesized by wet-solid phase mechanochemical processing, Ce_2(CO_3)_3·8H_2O, ZrOCl_2·xH_2O and ammonia were used as reactants. It is found that the crystalline Ce_2(CO_3)_3·8H_2O and ZrOCl_2·xH_2O are changed to amorphous cerium and zirconium hydroxide precursor after milling with ammonia, and Ce_(0.15)Zr_(0.85)O_2 mixed oxide with pure tetragonal phase structure and medium particle size(D_(50))less than 1μm is formed by calcining precursor over 673 K. The XRD patterns indicate that the crystal unite size increases with rising calcining temperature due to crystal growth. However, the particle size and BET surface area of the Ce(Zr)O_2 mixed oxide decreases with rising calcining temperature, which may be attributed to the contract of particles and the vanish of holes inside grains.展开更多
Silver powder was fabricated by spray pyrolysis, using 2%-20% AgNO3 solution, 336-500 mL/h flux of AgNO3 solution, 0.28-0.32 MPa flux of carrier gas and in the 620-820 ℃ temperature range. The effects of furnace set ...Silver powder was fabricated by spray pyrolysis, using 2%-20% AgNO3 solution, 336-500 mL/h flux of AgNO3 solution, 0.28-0.32 MPa flux of carrier gas and in the 620-820 ℃ temperature range. The effects of furnace set temperature, concentration of AgNO3 aqueous solution, flux of AgNO3 aqueous solution as well as carrier gas on the morphology and particle size distribution of silver powder, were investigated. The experimental results showed that with the high concentration of AgNO3 aqueous solution, the average grain size of silver decreased with the increasing of furnace set temperature. But the gain size distribution was not homogenous, the discontinuous grain growth occurred. With the low concentration of AgNO3 aqueous solution, the higher furnace set temperature made the nano sliver grains sintered together to grow. Nano silver powder about 100 nm was fabricated by spray pyrolysis, using 2wt% AgNO3 solutions, 336 mL/h flux of AgNO3 aqueous solution, 0.32 MPa flux of carrier gas at 720 ℃ furnace set temperature.展开更多
[Objectives]The effects of water chestnut powder on the gel properties and quality of silver carp surimi were investigated.[Methods]The surimi gel was prepared by adding 0%,1%,2%,3%,4%and 5%of water chestnut powder to...[Objectives]The effects of water chestnut powder on the gel properties and quality of silver carp surimi were investigated.[Methods]The surimi gel was prepared by adding 0%,1%,2%,3%,4%and 5%of water chestnut powder to the surimi of silver carp.The gel properties,water-holding capacity,cooking loss,whiteness value,puncture and texture profile analysis(TPA)indexes of surimi products were determined to assess the effects of adding different amounts of water chestnut powder on surimi gel.[Results]The results showed that the gel strength,breaking force and depression distance of surimi products increased first and then decreased with the increase of the addition of water chestnut powder.Compared with the control group,the hardness and chewiness of surimi gel in TPA could be significantly improved by adding water chestnut powder.When the addition of water chestnut powder was 2%,the maximum water-holding capacity was 83.68%;the cooking loss rate was the lowest;and the whiteness value was the highest.Adding 2%of water chestnut powder could significantly improve the gel properties of silver carp surimi and obtain a good gel product.[Conclusions]This study provides a scientific basis for the effective utilization of water chestnut resources and the development of new fish surimi products.展开更多
Antibacterial powders of titanium dioxide/silver sulfate were produced by heat-treatment of the metatitanic acid, as precursor, into which the silver nitrate was added. The influences of heating temperature on the str...Antibacterial powders of titanium dioxide/silver sulfate were produced by heat-treatment of the metatitanic acid, as precursor, into which the silver nitrate was added. The influences of heating temperature on the structure and composition of the product were investigated through XRD and SEM. The results show that the powder is spherical in the phase of TiO2-Ag2SO4. The granularity of the particles increases from 10.7nm to 28.7nm with the temperature of heat-treatment increasing from 300℃ to 800℃. The antibacterial activity of the powder was judged in the way of the minimum inhibitory contents (MiCs). When the content of silver sulfate is less than 2%, the photocatalysis of titanium dioxide and silver ions cooperate to kill bacteria. And the MiCs decrease and keep around 1.0×10 -41.5×10 -4 constantly with the increase of silver content. Furthermore, the MiCs decrease with the increase of temperature of heat-treatment when the temperature is lower than 500℃. But when the temperature is beyond 600℃ the MiCs increase quickly, which shows the inferior antibacterial performance.展开更多
Maki-e is a traditional Japanese decorative technique that uses the natural lacquer Urushi and metal powders. In 2014, there exist only two companies that manufacture silver powder for the purpose of Maki-e, and this ...Maki-e is a traditional Japanese decorative technique that uses the natural lacquer Urushi and metal powders. In 2014, there exist only two companies that manufacture silver powder for the purpose of Maki-e, and this study focuses on comparing the powders manufactured by them. Gloss and color of each silver powder were measured after Maki-e decoration was finished, and EDS (energy-dispersive X-ray spectroscopy) was used to determine the differences in their chemical composition. In addition, to verify the effect of polishing, residual gloss after sulfuration and polishing was measured. The study revealed that the shapes of the silver powders (Maru-fun, No. 1) manufactured by the two companies are different and it affects the occupancy rate of Urushi and powder, which in turn affects their gloss and color. Wakou silver has a very strong resistance to sulfuration;however, owing to its Pd content, its chroma is much lower than that of other powders. It was shown that sulfuration on powder surface can be removed by polishing irrespective of the shape and chemical composition ratio of the particles.展开更多
[Objectives]This study was conducted to improve the gel properties of freshwater surimi and its products. [Methods] Tuanfeng lotus seed powder was added to frozen silver carp, and the relationship between the addiamou...[Objectives]This study was conducted to improve the gel properties of freshwater surimi and its products. [Methods] Tuanfeng lotus seed powder was added to frozen silver carp, and the relationship between the addiamount of Tuanfeng lotus seed powder(1%, 2%, 3%, 4% and 5%) and the quality of surimi products was studied, so as to improve the quality of surimi products. [Results] The water holding capacity(86.71%±0.36%), hardness(3 566.64±51.15) g, chewiness(2 697.16±15.81) g and gel strength(692.54±23.19) of surimi products increased to the maximums when the addition amount of lotus seed powder was 3%. Meanwhile, the cooking loss rate was reduced to the minimum(13.00%±0.17%), and the sensory quality was the best, although the whiteness of surimi products decreased slightly with the increase of Tuanfeng lotus seed powder. Therefore, the quality of silver carp surimi products could be improved obviously when the dosage of Tuanfeng lotus seed powder was 3%. [Conclusions] This study provides more new ideas for improving the quality of silver carp surimi products, and simultaneously makes the development of lotus seed food more diversified.展开更多
基金Project supported by the National Natural Science Foundation of China (50474022 and 50574069 )
文摘Cerium carbonate powders were produced in a submerged circulation impinging stream reactor (SCISR) from Ce(NO3)3· 6H2O. NH4HCO3 was used as a precipitant in the reaction. Cerium carbonate powders were roasted to produce ultra-fine cerium dioxide (CeO2) powders. The optimal conditions of such production process were obtained by orthogonal and one-factor experiments. The results showed that ultra-fine and narrowly distributed cerium carbonate powders were produced under the optimal flowing conditions. The concentrations of Ce(NO3)3 and NH4HCO3 solutions were 02,5 and 0.3 mol · L^-1, respectively. The concentration of PEG4000 added in these two solutions was 4 g · L^-1. The stirring ratio, reaction temperature, feeding time, solution pH, reaction time and digestion time were 900 r · min^- 1,80 ℃, 20 min, 5 - 6, 5 min and 1 h, respectively. The final product, CeO2 powders, was obtained by roasting the produced cerium carbonate in air for 3 h at 500 ℃. The finally produced CeO2 powders were torispherical particles with a narrow size distribution of 0.8 -2.5 μm. The crystal structure of CeO2 powders belonged to cubic crystal system and its space point 5 group was OH^5-FM3M. Under optimal conditions, powders produced by SCISR were finer and more narrowly distributed than that by Stirred Tank Reactor (STR).
基金This work was supported by the National Science Fund for Distinguished Young Scholars of China (No.50125312) andSpecial Funds for Major State Basic Research Projects (No.G1999064800).
文摘Dynamic rheological characteristics of polypropylene (PP) filled with ultra-fine full-vulcanized powdered rubber (UFPR) composed of styrene-butadiene copolymer were studied through dynamic rheological measurements on an Advanced Rheometric Expansion System (ARES). A specific viscoelastic phenomenon, i.e. 'the second plateau', appeared at low frequencies, and exhibits a certain dependence on the amount of rubber particles and the dispersion state in the matrix. This phenomenon is attributed to the formation of aggregation structure of rubber particles. The analyses of Cole-Cole diagrams of the dynamic viscoelastic functions suggest that the heterogeneity of the composites is enhanced on increasing both particle content and temperature.
基金Funded by the Key Program Project of the National Natural Science Foundation of China (No.50234040)the Major Project of the Knowledge Innovation Program of the Chinese Academy of Sciences (No.KCCX1-SW-22)
文摘The ultra-fine chromic oxide powder was prepared by a novel gas-solid reduction reaction.Na2CrO4 was firstly reduced with hydrogen at 400-600 ℃.The obtained reduction products,mainly the mixture of NaCrO2 and sodium hydroxide(NaOH),were converted into chromic oxide through hydrolysis followed by calcination.The obtained chromic oxide product was characterized by powder X-ray diffraction(XRD) and SEM.The results show that the hydrolysis process of sodium chromite is the key step and lower reduction temperature helps intensify the hydrolysis process.
基金financially supported by the National Natural Science Foundation of China(grant no.51204028)
文摘In this study, three kinds of modified ultra-fine ceramic powders marked A, B and C, which were prepared by each of three different modifiers mixing with a commercial SiC, were added to HT250 cast iron, respectively, and the effects of the modified ultra-fine ceramic powders on microstructure, mechanical properties and wear resistance were studied. Metallographic examination, tensile test, scanning electron microscopy, and three-dimensional surface topography were applied to analyze and compare the samples containing modified powder with the original samples. The results showed that the most obvious modification effect among the powders was seen in the sample containing powder A, with the graphite and eutectic cells being refined, the tensile strength being increased by 36.9%, and the wear resistance being improved by 45.5% and 47.2% under loads of 150 N and 300 N, respectively. The improvements of mechanical properties and wear resistance in the HT250 cast iron with the modified ultra-fine ceramic powders were attributed to the synergistic effect of the grain refinement with the powder acting as a hard particle phase and the lubrication by the graphite.
文摘Ultra-fine CeO_2-ZrO_2 mixed oxide was successfully synthesized by wet-solid phase mechanochemical processing, Ce_2(CO_3)_3·8H_2O, ZrOCl_2·xH_2O and ammonia were used as reactants. It is found that the crystalline Ce_2(CO_3)_3·8H_2O and ZrOCl_2·xH_2O are changed to amorphous cerium and zirconium hydroxide precursor after milling with ammonia, and Ce_(0.15)Zr_(0.85)O_2 mixed oxide with pure tetragonal phase structure and medium particle size(D_(50))less than 1μm is formed by calcining precursor over 673 K. The XRD patterns indicate that the crystal unite size increases with rising calcining temperature due to crystal growth. However, the particle size and BET surface area of the Ce(Zr)O_2 mixed oxide decreases with rising calcining temperature, which may be attributed to the contract of particles and the vanish of holes inside grains.
文摘Silver powder was fabricated by spray pyrolysis, using 2%-20% AgNO3 solution, 336-500 mL/h flux of AgNO3 solution, 0.28-0.32 MPa flux of carrier gas and in the 620-820 ℃ temperature range. The effects of furnace set temperature, concentration of AgNO3 aqueous solution, flux of AgNO3 aqueous solution as well as carrier gas on the morphology and particle size distribution of silver powder, were investigated. The experimental results showed that with the high concentration of AgNO3 aqueous solution, the average grain size of silver decreased with the increasing of furnace set temperature. But the gain size distribution was not homogenous, the discontinuous grain growth occurred. With the low concentration of AgNO3 aqueous solution, the higher furnace set temperature made the nano sliver grains sintered together to grow. Nano silver powder about 100 nm was fabricated by spray pyrolysis, using 2wt% AgNO3 solutions, 336 mL/h flux of AgNO3 aqueous solution, 0.32 MPa flux of carrier gas at 720 ℃ furnace set temperature.
基金Supported by High-level Cultivation Project of Huanggang Normal University(04201711903).
文摘[Objectives]The effects of water chestnut powder on the gel properties and quality of silver carp surimi were investigated.[Methods]The surimi gel was prepared by adding 0%,1%,2%,3%,4%and 5%of water chestnut powder to the surimi of silver carp.The gel properties,water-holding capacity,cooking loss,whiteness value,puncture and texture profile analysis(TPA)indexes of surimi products were determined to assess the effects of adding different amounts of water chestnut powder on surimi gel.[Results]The results showed that the gel strength,breaking force and depression distance of surimi products increased first and then decreased with the increase of the addition of water chestnut powder.Compared with the control group,the hardness and chewiness of surimi gel in TPA could be significantly improved by adding water chestnut powder.When the addition of water chestnut powder was 2%,the maximum water-holding capacity was 83.68%;the cooking loss rate was the lowest;and the whiteness value was the highest.Adding 2%of water chestnut powder could significantly improve the gel properties of silver carp surimi and obtain a good gel product.[Conclusions]This study provides a scientific basis for the effective utilization of water chestnut resources and the development of new fish surimi products.
文摘Antibacterial powders of titanium dioxide/silver sulfate were produced by heat-treatment of the metatitanic acid, as precursor, into which the silver nitrate was added. The influences of heating temperature on the structure and composition of the product were investigated through XRD and SEM. The results show that the powder is spherical in the phase of TiO2-Ag2SO4. The granularity of the particles increases from 10.7nm to 28.7nm with the temperature of heat-treatment increasing from 300℃ to 800℃. The antibacterial activity of the powder was judged in the way of the minimum inhibitory contents (MiCs). When the content of silver sulfate is less than 2%, the photocatalysis of titanium dioxide and silver ions cooperate to kill bacteria. And the MiCs decrease and keep around 1.0×10 -41.5×10 -4 constantly with the increase of silver content. Furthermore, the MiCs decrease with the increase of temperature of heat-treatment when the temperature is lower than 500℃. But when the temperature is beyond 600℃ the MiCs increase quickly, which shows the inferior antibacterial performance.
文摘Maki-e is a traditional Japanese decorative technique that uses the natural lacquer Urushi and metal powders. In 2014, there exist only two companies that manufacture silver powder for the purpose of Maki-e, and this study focuses on comparing the powders manufactured by them. Gloss and color of each silver powder were measured after Maki-e decoration was finished, and EDS (energy-dispersive X-ray spectroscopy) was used to determine the differences in their chemical composition. In addition, to verify the effect of polishing, residual gloss after sulfuration and polishing was measured. The study revealed that the shapes of the silver powders (Maru-fun, No. 1) manufactured by the two companies are different and it affects the occupancy rate of Urushi and powder, which in turn affects their gloss and color. Wakou silver has a very strong resistance to sulfuration;however, owing to its Pd content, its chroma is much lower than that of other powders. It was shown that sulfuration on powder surface can be removed by polishing irrespective of the shape and chemical composition ratio of the particles.
基金Supported by Scientific Research Program Steering Group Project of Department of Education of Hubei Province (B2020166)。
文摘[Objectives]This study was conducted to improve the gel properties of freshwater surimi and its products. [Methods] Tuanfeng lotus seed powder was added to frozen silver carp, and the relationship between the addiamount of Tuanfeng lotus seed powder(1%, 2%, 3%, 4% and 5%) and the quality of surimi products was studied, so as to improve the quality of surimi products. [Results] The water holding capacity(86.71%±0.36%), hardness(3 566.64±51.15) g, chewiness(2 697.16±15.81) g and gel strength(692.54±23.19) of surimi products increased to the maximums when the addition amount of lotus seed powder was 3%. Meanwhile, the cooking loss rate was reduced to the minimum(13.00%±0.17%), and the sensory quality was the best, although the whiteness of surimi products decreased slightly with the increase of Tuanfeng lotus seed powder. Therefore, the quality of silver carp surimi products could be improved obviously when the dosage of Tuanfeng lotus seed powder was 3%. [Conclusions] This study provides more new ideas for improving the quality of silver carp surimi products, and simultaneously makes the development of lotus seed food more diversified.