The effects of different curing systems on the properties of high volume fine mineral powder RPC （reactive powder concrete） and the appearances of hydrates were studied. The experimental results show that dry-heatin...The effects of different curing systems on the properties of high volume fine mineral powder RPC （reactive powder concrete） and the appearances of hydrates were studied. The experimental results show that dry-heating curing promotes the development of pozzolanic reactivity of fine mineral powder; due to low cement content, 0.20 water-bind ratio and high reactive fine mineral powder content, the strength of RPC increases by around 200% after steam curing and subsequent dry-heating curing. Scanning electron microscopy and energy spectrum diagram showed that： after the high volume fine mineral powder RPC with 0.16 water-bind ratio underwent steam curing and dry-heating curing, there was no significant change in the appearance of hydrates; after the RPC with 0.20 water-bind ratio, the cement content of 150 kg/m3 and more steel slag powder underwent dry-heating curing, there was a certain change in the appearance of C-S-H, the structure of gel was more compact and was uniformly distributed, and the Ca/Si of C-S-H gel decreased from 1.41 to around 1.20.展开更多
The effects of preheating temperature and W powder size on the Self propagating High temperature Synthesis(SHS) of Ti W C system were studied. Preheated mixtures and the decrease of W powder size can accelerate the fo...The effects of preheating temperature and W powder size on the Self propagating High temperature Synthesis(SHS) of Ti W C system were studied. Preheated mixtures and the decrease of W powder size can accelerate the formation of (W,Ti)C powders. The uniphase (W,Ti)C (WC∶TiC=5∶5) powders with 0.32% free carbon were synthesized from Ti, W, C powders by SHS. The powder size of the product was 3～5 μm.展开更多
A dry mechanical surface treatment was described, in which irregularly shaped metal powders were impacted and sphericized by using high speed airflow impact method particles composite system(PCS). The optimum technolo...A dry mechanical surface treatment was described, in which irregularly shaped metal powders were impacted and sphericized by using high speed airflow impact method particles composite system(PCS). The optimum technological parameters for the metal powders processed were determined according to the treatment effect under different conditions. The results show that the irregularly shaped metal powders are impacted into dense spherical particles, the bulk density and tap density of the metal powders increase noticeably. The combination property of metal powders is improved greatly.展开更多
A new compound K6FeNb15O42 was prepared for the first time by solid state reaction in K2O-Fe2O3-Nb2O5 ternary system. The X-ray powder diffraction data of the title compound was measured. K6FeNb15 O42 crystallizes in ...A new compound K6FeNb15O42 was prepared for the first time by solid state reaction in K2O-Fe2O3-Nb2O5 ternary system. The X-ray powder diffraction data of the title compound was measured. K6FeNb15 O42 crystallizes in the hexagonal system with unit cell parameters, a = 9. 1320(4) A ,c = 12. 0670(9) A , and space group P63/mcm (193) , z = 1. The calculated and measured densities are 4. 489 g/cm3 and 4. 485 g. cm3, respectively.展开更多
A new compound K6FeNb15O42 u(?) prepared for the first time by solid state reaction in K2O-Fe2O3-Nb2O5 ternary system. The XRD data of the title compound was determined. K6FeNb15O42 crystallizes the hexagonal system w...A new compound K6FeNb15O42 u(?) prepared for the first time by solid state reaction in K2O-Fe2O3-Nb2O5 ternary system. The XRD data of the title compound was determined. K6FeNb15O42 crystallizes the hexagonal system with unit cell parameters a=9. 1320(4) A,c=12. 0670(9) A, and space group P63/mcm(193) , 2=1. The calculated and measured densities are 4. 489 g/ cm3 and 4. 485 g. cm3, respectively.展开更多
Self-propagating high-temperature synthesis（SHS） method was used to synthesize ZrB2/Al2O3 composite powders from B2O3-ZrO2-Al system. X-ray diffractometry（XRD） and scanning electron microscopy（SEM） analyses show...Self-propagating high-temperature synthesis（SHS） method was used to synthesize ZrB2/Al2O3 composite powders from B2O3-ZrO2-Al system. X-ray diffractometry（XRD） and scanning electron microscopy（SEM） analyses show the presence of ZrB2 and Al2O3 as the primary phases in the composite powders, while the presence of a very small amount of ZrO2 is thought to be unreacted zirconium oxide. Transmission electron microscopy（TEM） and high resolution electron microscopy（HREM） observations of microstructure of the composite powders indicate that the interfaces of ZrB2/Al2O3 bond well without any interfacial reaction products. It is proposed that the good interfacial bonding of composite powders results from the ZrB2 particles crystallizing and growing on the Al2O3 particles surface with surface defects acting as nucleation centers.展开更多
A new compound Ba6Ti7Nb9O42 was prepared for the first time by solid state reaction in BaO-TiO2-Nb2O5, ternary system. The X-ray powder diffraction data of the title compound was determined. Ba6Ti7Nb9O42 crystallizes ...A new compound Ba6Ti7Nb9O42 was prepared for the first time by solid state reaction in BaO-TiO2-Nb2O5, ternary system. The X-ray powder diffraction data of the title compound was determined. Ba6Ti7Nb9O42 crystallizes in the hexagonal system -with unit cell parameters a=9.0527(4) A,c=11.790(1) A,and space group P63/mcm(193),z=1. The calculated and measured densities are 5. 293 g/cm3 and 5.285 g/cm3, respectively.展开更多
TiB2 powders coated with BN were prepared by Hybridization System making use of dry impact blending method to achieve powder surface modification. Parameters of coating were analyzed and the most appropriate condition...TiB2 powders coated with BN were prepared by Hybridization System making use of dry impact blending method to achieve powder surface modification. Parameters of coating were analyzed and the most appropriate condition was summarized. Scan electron microscope of JSM-5610LV and transmission electron microscope of H-600STEM/EDS were used to observe the microstructure of coated powders. Results show that treatment time, rotation speed, granularity ratio of TiB2 to BN, pretreatment of materials etc influence the coating results evidently. Mixing raw materials and coating with BN under the appropriate condition can get round TiB2/BN composite powder with smooth surface and compact coating layer.展开更多
TiB2-Al2O3 composite powders were produced by self-propagating high-temperature synthesis（SHS） method with reductive process from B2O3-TiO2-AI system. X-ray diffraction（XRD） and scanning electron microscopy（SEM...TiB2-Al2O3 composite powders were produced by self-propagating high-temperature synthesis（SHS） method with reductive process from B2O3-TiO2-AI system. X-ray diffraction（XRD） and scanning electron microscopy（SEM） analyses show the presence of TiB2 and Al2O3 only in the composite powders produced by SHS. The powders are uniform and free-agglomerate. Transmission electron microscopy （TEM） and high resolution electron microscopy （HREM） observation of microstructure of the composite powders indicate that the interfaces of the TiB2-Al2O3 bond well, without any interfacial reaction products. It is proposed that the good interfacial bonding of the composite powders can be resulted from the TiB2 particles crystallizing and growing on the Al2O3 particles surface with surface defects acting as nucleation centers.展开更多
基金Funded by the Science and Technology Foundation of Beijing Municipal Education Commission (KM200410016004)
文摘The effects of different curing systems on the properties of high volume fine mineral powder RPC （reactive powder concrete） and the appearances of hydrates were studied. The experimental results show that dry-heating curing promotes the development of pozzolanic reactivity of fine mineral powder; due to low cement content, 0.20 water-bind ratio and high reactive fine mineral powder content, the strength of RPC increases by around 200% after steam curing and subsequent dry-heating curing. Scanning electron microscopy and energy spectrum diagram showed that： after the high volume fine mineral powder RPC with 0.16 water-bind ratio underwent steam curing and dry-heating curing, there was no significant change in the appearance of hydrates; after the RPC with 0.20 water-bind ratio, the cement content of 150 kg/m3 and more steel slag powder underwent dry-heating curing, there was a certain change in the appearance of C-S-H, the structure of gel was more compact and was uniformly distributed, and the Ca/Si of C-S-H gel decreased from 1.41 to around 1.20.
文摘The effects of preheating temperature and W powder size on the Self propagating High temperature Synthesis(SHS) of Ti W C system were studied. Preheated mixtures and the decrease of W powder size can accelerate the formation of (W,Ti)C powders. The uniphase (W,Ti)C (WC∶TiC=5∶5) powders with 0.32% free carbon were synthesized from Ti, W, C powders by SHS. The powder size of the product was 3～5 μm.
基金Project(50474003) supported by the National Natural Science Foundation of China
文摘A dry mechanical surface treatment was described, in which irregularly shaped metal powders were impacted and sphericized by using high speed airflow impact method particles composite system(PCS). The optimum technological parameters for the metal powders processed were determined according to the treatment effect under different conditions. The results show that the irregularly shaped metal powders are impacted into dense spherical particles, the bulk density and tap density of the metal powders increase noticeably. The combination property of metal powders is improved greatly.
基金Fund by International Centre for Dlffractlon Data.
文摘A new compound K6FeNb15O42 was prepared for the first time by solid state reaction in K2O-Fe2O3-Nb2O5 ternary system. The X-ray powder diffraction data of the title compound was measured. K6FeNb15 O42 crystallizes in the hexagonal system with unit cell parameters, a = 9. 1320(4) A ,c = 12. 0670(9) A , and space group P63/mcm (193) , z = 1. The calculated and measured densities are 4. 489 g/cm3 and 4. 485 g. cm3, respectively.
文摘A new compound K6FeNb15O42 u(?) prepared for the first time by solid state reaction in K2O-Fe2O3-Nb2O5 ternary system. The XRD data of the title compound was determined. K6FeNb15O42 crystallizes the hexagonal system with unit cell parameters a=9. 1320(4) A,c=12. 0670(9) A, and space group P63/mcm(193) , 2=1. The calculated and measured densities are 4. 489 g/ cm3 and 4. 485 g. cm3, respectively.
基金Project(KNH2021005) supported by Industrialization Programof Economic Committee of Shanghai
文摘Self-propagating high-temperature synthesis（SHS） method was used to synthesize ZrB2/Al2O3 composite powders from B2O3-ZrO2-Al system. X-ray diffractometry（XRD） and scanning electron microscopy（SEM） analyses show the presence of ZrB2 and Al2O3 as the primary phases in the composite powders, while the presence of a very small amount of ZrO2 is thought to be unreacted zirconium oxide. Transmission electron microscopy（TEM） and high resolution electron microscopy（HREM） observations of microstructure of the composite powders indicate that the interfaces of ZrB2/Al2O3 bond well without any interfacial reaction products. It is proposed that the good interfacial bonding of composite powders results from the ZrB2 particles crystallizing and growing on the Al2O3 particles surface with surface defects acting as nucleation centers.
基金Fund by International Centre for diffraction Data.
文摘A new compound Ba6Ti7Nb9O42 was prepared for the first time by solid state reaction in BaO-TiO2-Nb2O5, ternary system. The X-ray powder diffraction data of the title compound was determined. Ba6Ti7Nb9O42 crystallizes in the hexagonal system -with unit cell parameters a=9.0527(4) A,c=11.790(1) A,and space group P63/mcm(193),z=1. The calculated and measured densities are 5. 293 g/cm3 and 5.285 g/cm3, respectively.
基金Project(50372047) supported by the National Natural Science Foundation of China
文摘TiB2 powders coated with BN were prepared by Hybridization System making use of dry impact blending method to achieve powder surface modification. Parameters of coating were analyzed and the most appropriate condition was summarized. Scan electron microscope of JSM-5610LV and transmission electron microscope of H-600STEM/EDS were used to observe the microstructure of coated powders. Results show that treatment time, rotation speed, granularity ratio of TiB2 to BN, pretreatment of materials etc influence the coating results evidently. Mixing raw materials and coating with BN under the appropriate condition can get round TiB2/BN composite powder with smooth surface and compact coating layer.
文摘TiB2-Al2O3 composite powders were produced by self-propagating high-temperature synthesis（SHS） method with reductive process from B2O3-TiO2-AI system. X-ray diffraction（XRD） and scanning electron microscopy（SEM） analyses show the presence of TiB2 and Al2O3 only in the composite powders produced by SHS. The powders are uniform and free-agglomerate. Transmission electron microscopy （TEM） and high resolution electron microscopy （HREM） observation of microstructure of the composite powders indicate that the interfaces of the TiB2-Al2O3 bond well, without any interfacial reaction products. It is proposed that the good interfacial bonding of the composite powders can be resulted from the TiB2 particles crystallizing and growing on the Al2O3 particles surface with surface defects acting as nucleation centers.
