Self-ordering of the cell arrangement of the anodic porous alumina was prepared in oxalic acid solution at a constant potential of 40V and at a temperature of 20C. The honeycomb structure made by one step anodization...Self-ordering of the cell arrangement of the anodic porous alumina was prepared in oxalic acid solution at a constant potential of 40V and at a temperature of 20C. The honeycomb structure made by one step anodization method and two step anodization method is different. Pores in the alumina film prepared by two step anodization method were more ordered than those by one step anodization method.展开更多
The cyclic oxidation behavior of Hf/Y-doped B2 FeAl intermetallics at 1373 K was investigated.For an undoped FeAl alloy,premature spallation of the alumina film occurs due to the formation of numerous voids at the fil...The cyclic oxidation behavior of Hf/Y-doped B2 FeAl intermetallics at 1373 K was investigated.For an undoped FeAl alloy,premature spallation of the alumina film occurs due to the formation of numerous voids at the film/alloy interface and apparent shrinkage in the film.In contrast to this,doping with either Hf or Y significantly improves the interfacial adhesion between the alumina film and the alloy substrate,particularly with Hf-doping.Microstructural observation in combination with Anger electron spectroscopic analysis suggests that in addition to prohibiting interfacial void formation and alleviating film shrinkage,the addition of Hf in the FeAl alloy could consolidate the film/alloy interface by directly participating in chemical bonding across the interface as a Hf ion.This causes the spallation of alumina film from the equiaxed grains/columnar grains interface rather than the bottom of the film.展开更多
Photoluminescence (PL) properties of porous anodic alumina (PAA) films prepared by using electrochemical anodization technique in a mixed solution of oxalic and sulfuric acid have been investigated. The PAA films have...Photoluminescence (PL) properties of porous anodic alumina (PAA) films prepared by using electrochemical anodization technique in a mixed solution of oxalic and sulfuric acid have been investigated. The PAA films have an intensive ultraviolet PL emission around 350 nm, of which a possible PL mechanism has been proposed. It was found that the incorporated oxalic ions, which could transform into PL centers and exist in the PAA films, are responsible for this ultraviolet PL emission.展开更多
Magnetic Co nanodots embedded in the porous anodic alumina films(AAFs)on silicon substrate can be used as the magnetic recording material with high area recording density.For this purpose,pure aluminum films were depo...Magnetic Co nanodots embedded in the porous anodic alumina films(AAFs)on silicon substrate can be used as the magnetic recording material with high area recording density.For this purpose,pure aluminum films were deposited on Si substrate with the Electron Cyclotron Resonance(ECR)plasma sputtering technique,and AAFs with vertical nano holes were synthesized with the two-step anodization process in oxalic acid.Finally magnetic material Co was deposited into the nano holes with electrochemical method.The results showed that polycrystalline ECR-Al films are homogenous and fit for the synthesis of AAFs with uniform distributed nano holes when ion sheath formed in front of the substrate surface.The diameters of AAF nano holes were in the range from 30 to 70 nm,and the hole pitches were approximately 100 nm,the AAF on silicon substrate was about 100 nm thick after two-step anodization.Magnetic Co nanodots filled into the nano holes of AAF exhibited both fcc and hcp structures.展开更多
文摘Self-ordering of the cell arrangement of the anodic porous alumina was prepared in oxalic acid solution at a constant potential of 40V and at a temperature of 20C. The honeycomb structure made by one step anodization method and two step anodization method is different. Pores in the alumina film prepared by two step anodization method were more ordered than those by one step anodization method.
基金financially supported by the Basic Research Program of State Grid(No.GCB17201600179)
文摘The cyclic oxidation behavior of Hf/Y-doped B2 FeAl intermetallics at 1373 K was investigated.For an undoped FeAl alloy,premature spallation of the alumina film occurs due to the formation of numerous voids at the film/alloy interface and apparent shrinkage in the film.In contrast to this,doping with either Hf or Y significantly improves the interfacial adhesion between the alumina film and the alloy substrate,particularly with Hf-doping.Microstructural observation in combination with Anger electron spectroscopic analysis suggests that in addition to prohibiting interfacial void formation and alleviating film shrinkage,the addition of Hf in the FeAl alloy could consolidate the film/alloy interface by directly participating in chemical bonding across the interface as a Hf ion.This causes the spallation of alumina film from the equiaxed grains/columnar grains interface rather than the bottom of the film.
基金This work was supported by the Natural Science Foundation of China(Grant No.19974055)the National Major Project of Fundamental Research(Grant No.19994506).
文摘Photoluminescence (PL) properties of porous anodic alumina (PAA) films prepared by using electrochemical anodization technique in a mixed solution of oxalic and sulfuric acid have been investigated. The PAA films have an intensive ultraviolet PL emission around 350 nm, of which a possible PL mechanism has been proposed. It was found that the incorporated oxalic ions, which could transform into PL centers and exist in the PAA films, are responsible for this ultraviolet PL emission.
基金NSFC(90923027 and 51050110137)The Fundamental Research Funds for Central Universities
文摘Magnetic Co nanodots embedded in the porous anodic alumina films(AAFs)on silicon substrate can be used as the magnetic recording material with high area recording density.For this purpose,pure aluminum films were deposited on Si substrate with the Electron Cyclotron Resonance(ECR)plasma sputtering technique,and AAFs with vertical nano holes were synthesized with the two-step anodization process in oxalic acid.Finally magnetic material Co was deposited into the nano holes with electrochemical method.The results showed that polycrystalline ECR-Al films are homogenous and fit for the synthesis of AAFs with uniform distributed nano holes when ion sheath formed in front of the substrate surface.The diameters of AAF nano holes were in the range from 30 to 70 nm,and the hole pitches were approximately 100 nm,the AAF on silicon substrate was about 100 nm thick after two-step anodization.Magnetic Co nanodots filled into the nano holes of AAF exhibited both fcc and hcp structures.
