首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
At present, in cast iron fine melting, lowering phosphorus concentration with no loss ofother favorable elements at the same timeseems to be a problem, which still has notbeen solved thoroughly. Therefore, looking foran appropriate nodulizer to modify the morphology of phosphide eutectic, especially inhigh strength cast iron, is necessary. On theother hand, phosphorous can also exhibit itsfaVorable effect on mechanical properties aswell as processing behaviors. For instance,gray cast iron cont…  相似文献   

2.
Microstructures and crack extending characteristic of the YG8R,YT5R and YT14R hard alloysadding a trace cerium were studied by AEM and HVEM with a tensile holder.In the hard alloys addingcerium,the compounds of Ce_2O_3 or Ce_2O_2S could be formed,extending of stacking faults and transforma-tion from fcc Co to hcp Co were suppressed,volume fraction of fcc Co in the alloys was increased,andstrength of Co and(TiW)C phases and grain boundaries were raised.Plastic deformation in Co phase nearedges of the tensile cracks was more strong,and the tensile cracks could pass through some smaller WCgrains.  相似文献   

3.
Effect of Additive on Microstructure of Transparent YAG Ceramics   总被引:2,自引:0,他引:2  
Crystallineyttriumaluminumgarnet (Y3 Al5O12 )isanimportantlasermaterialduetoitssuperioropti calandmechanicalproperties[1,2 ] .NeodymiumdopedYAGisusedwidelyaslaserhostmaterialinvarioussolidstatelasers .SingleYAGcrystalsaregenerallysynthesizedbyCzochralskim…  相似文献   

4.
Effect of BaO on Catalytic Activity of Pt-Rh TWC   总被引:1,自引:1,他引:0  
The effect of BaO doping to the Pt-Rh catalysts on its three-way catalytic activity and water-gas transfer was investigated. The results show that the light-off temperatures of hydrocarbon and carbon monoxide and nitrogen oxides have little difference in the fresh catalysts. But after the hydrothermal-aged 5 h at 1000 ℃, the catalysts containing CeO2-ZrO2-BaO has lower light-off temperature and better catalytic activity than the catalysts containing BaO and CeO2-ZrO2,  相似文献   

5.
Metal foams are usually used as light structural/functional materials.The nucleation,evolution and the solidification behavior of the metal foams can be influenced by the stirring mode and the foaming parameters.In this paper,the effects of electromagnetic stirring on metal foaming process were investigated.Comparative tests were carried out and the optimized parameters of the stirring modes were discussed.The stirring effects of the spiral electromagnetic field are better than the travelling wave electromagnetic field.The effects of the spiral electromagnetic-mechanical combined stirring are better than the situations of the single electromagnetic stirring or the single mechanical stirring.  相似文献   

6.
7.
The effects of BaO doping on the three-way catalytic activity of Pt-Rh catalyst and on water-gas shift were investigated. The results show that the light-off temperatures of hydrocarbon and carbon monoxide and nitrogen oxides of the fresh catalysts slightly differ from those of the aged catalysts, and the catalysts containing CeO2-ZrO2-BaO have lower lightoff temperature and better catalytic activity than these containing BaO and CeO2-ZrO2 after hydrothermal aging for 5 h at 1000 ℃. The catalysts were characterized by means of the temperature-programmed reduction (TPR) in hydrogen and the temperature-programmed desorption (TPD) in oxygen. It is confirmed that the suggested route of CeO2-ZrO2-BaO by coprecipitation can improve the catalytic activity of catalysts.  相似文献   

8.
A new catalyst support, Ce-Mg-O, was prepared in a novel way macromolecule surfactant modified method and was used as a catalyst support for low-temperature methane combustion. The results indicate that the new type of FeOx/Ce- Mg-O catalyst exhibits high activity in low-temperature methane combustion, such that the T90 at which 90% conversion of methane occurs can be obtained at 560 ℃. The structure of the catalyst and the effect of the supporter on catalytic activity were characterized by transmission electronic microscopy (TEM), X-ray diffraction (XRD), and temperature-programmed reduction (TPR). The results indicate that the high catalytic activity of FeOx/Ce-Mg-O over methane combustion is strongly dependent on the particle size, typical crystal phase of the Ce-Mg-O, and the interaction of FeOx and Ce-Mg-O.  相似文献   

9.
Effect of Nd^3+ on Photosynthesis of Spinach   总被引:5,自引:0,他引:5  
The effect of Nd^3 on the photosynthesis and the growth of spinach was studied. The results show that Nd^3 improves the growth of spinach and increases chlorophyll content and photosynthetic rate. UV-Vis spectrum indicates that the Soret band of chl-a in spinach with NdCl3 treatment is blue shifted by 2 nm, and the Q band is red shifted by 1 nm, and the ratio of Soret band intensity and Q band intensity increases. FT-IR spectra show that the peak of porphyrin ring in chl-a of spinach with NdCl3 treatment is widened, suggesting that the formation of Nd^3 -chl-a. Treated by NdCl3, the fluorescence emission peak of PSⅡ in spinach leaves is blue shifted by 12 nm and the intensity declines obviously, indicating that Nd^3 is bound to the PSⅡ protein-pigment complex and the electron transfer rate increases.  相似文献   

10.
The performance of severe oxidation of methanol on 0.1%Pd supported on alumina was studied by a combined device of chromatograph-micro reactor,The results show that the addition of La intoγAl2O3as support can affect the performance of Pd catalyst greatly.By using Pd catalyst comtaining La in methanol oxidation,thouhg,the ignition temperature is not lower than than by using Pd catalyst,the presence of La does suppress the formation of oxygenic intermediates,The results by in-situ FTIR show that the presence of La in the support affects the adsorbed specties and hence the mechanism of severe oxidation of methanol on Pd catalyst.  相似文献   

11.
EffectofCeriumonLithium-AluminiumAnodeGuanCongsheng(管从胜),DuanShuzhen(段淑贞),ZhaoGuangwen(招光文)(DepartmentofPhysicalChemistry,Uni...  相似文献   

12.
In 192 2 ,AmericanMeehanappliedthefirstpatentforinoculatedcastiron .Nowtherearemorethan 10 0 0kindsofinoculantsintheworld .Thein oculationmeansthatsomematerialisputintomeltedirontocausesome physicalandchemicalchangeswhicharedifferentfromthosecausedbythealloyingelementinthecastiron .Intheearlydays ,themaincontentofinoculantwassilicon ,andsoonafterwardscalcium ,aluminium ,barium ,strontiumandmanga nese ,etcwereincluded .In 196 1,ceriumwasintro ducedintoinoculant .Nowtheinoculantsarewidelyappli…  相似文献   

13.
EffectofMicrostructureonTensilePropertiesofTiAlBasedAlloyPuZhongjie;ShiJiandong;ZouDunxu;ZhongZengyongAbstract:Themicrostruct...  相似文献   

14.
Effect of Cerium on Corrosion Resistance of Bright Zinc Electrodeposit   总被引:2,自引:0,他引:2  
EffectofCeriumonCorrosionResistanceofBrightZincElectrodepositLiShi-Jia(李士嘉);HeJian-Ping(何建平);ChenWang-Hua(陈网桦);ZhangYing(张英)(...  相似文献   

15.
Effect of Lanthanum on Disease Resistance Related Enzymes of Rape   总被引:2,自引:0,他引:2  
Thegrowthandtheabilitytoresistdiseaseofcropscanbeincreasedbyrareearthelements (REEs)ofsuitableconcentration[1,2 ] .ReportsshowedthatsprayingREEscandecreasethediseaseindexesofin fectedplants .Zhangetalfoundthatthegrowthofapathogenofrapeformingsclerotium (Sclerotiniascle rotiorum )couldbeinhibitedbyREEsofacertaincon centration[3] .ButonlyafewreportshavestudiedthemechanismofthediseaseresistanceinducedbyREEs.EspeciallytheactivityofenzymesrelatedtodiseaseresistanceaffectedbyREEs ,aswellasthe…  相似文献   

16.
Study was made on the effect of surface modification on the behaviors of cerium oxide nanopowders.A surfactant-sodium dodecyl sulfate(C12H25SO4Na)was used to modify the surface of CeO2 powder particles.The unmodified and modified CeO2 powders were characterized by using a powder comprehensive characteristic tester,laser particle size analyzer,specific surface area tester,X-ray diffraction tester,and a scanning electron microscope.The testing and analysis results showed that C12H25SO4Na surface modification might increase the flowability and dispersity,and decrease the specific surface area and agglomeration of CeO2 powders.The mechanism of the surface modification of CeO2 powder particles was also discussed.  相似文献   

17.
Effect of cerium addition on corrosion resistance of AZ91 magnesium alloy was investigated using the static weight loss and polarization curve method as well as metallographical observation. The results indicate that a small amount of cerium (0.2% - 0.8%) in AZ91 magnesium alloy can significantly reduce the corrosion rate, enhance the electrode voltage and lower corrosion current density in 3.5%NaCl aqueous solution, and AZ91-0.8% Ce alloy has better corrosion resistant performance. The reason for increasing corrosion resistance is attributed to the addition of Ce, refining the α-Mg grain, reducing the segregation of element Al, and improving the morphologies of β-Mg17 Al12 phases.  相似文献   

18.
The effects of rare earth on the growth of rice,rape and soybean in three kinds of soils were studied with the method supposed by Economic Co-operation and Development organization(OECD),and the EC50(median growth concenrtation)values were obtained,The inhibition of RE on the growth of rice and rape in red soil and on the growth of soybeanin yellow fouvo-aquic soil is higher with stronger poison effects.Compared with other heavy metals such as Hg,Cd,Pb,As,the poison of RE on crops in weaker.  相似文献   

19.
Itwasprovedbypreviousworks[1] thatrareearthelementspromotethegrowthandde velopmentofplantsandincreasetheyieldofcropsatlowconcentration ,butwhenthecon centrationishigh ,theywillinhibitthegrowthofplants .Itwasalsoproved[2 ,3] thatrareearthelementsexhibitbothpos…  相似文献   

20.
Rareearth (RE)micro fertilizershavebeenusedinagricultureproductioninChinasince 1 970s ,andthesemicro fertilizersaresaltsofmixedREs ,whichmainlyincludeLa ,Ce ,PrandNd[1,2 ] .PreviousstudiesshowthattheREinsurfacesoilalmostdoesnotmigratdownwardatallandthusbeaccumula…  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号