Development of protective metal coatings on aluminum by magnetron sputtering

Depositions of copper and titanium coatings on aluminum foils and polished aluminum plates for thier protection against corrosion in alkaline media were performed. The coatings were deposited in three different types of magnetron sputtering systems: a direct current (DC) magnetron discharge, a high current impulse magnetron discharge, and a DC magnetron discharge with melted cathode. Only aluminum foils coated with copper films obtained by combined ion-plasma technology, which included preliminarily sputtering of the aluminum surface with an ion beam, deposition of a dense interlayer in the DC magnetron discharge with ion assistance of initial stage of deposition, and deposition of additional layer in the magnetron discharge with melted cathode, were resistant against 30 wt % NaOH solution.     

Structural characterization of titanium oxide layers prepared by plasma based ion implantation with oxygen on Ti6Al4V alloy

Ti6Al4V alloy was implanted with oxygen by using plasma based ion implantation (PBII) at pulsed voltage ranging from −10 to −50 kV with a frequency of 100 Hz. In order to maintain a lower implantation temperature, an oil cooling working table was employed. The structure of the modified layers was characterized by X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. The results show that the thickness of the titanium oxide layer increases significantly with the increase of implanted voltage. The structure of the modified layer changes along depth. It is found that the surface layer consists of TiO₂, and the subsurface layer is a mixing structure of TiO_2, Ti₂O₃ and TiO. There is crystalline rutile phase existing in the modified layer of sample implanted at high implanted voltage. In addition, in the outmost modified surface, aluminum present as oxidized state, and vanadium could not be detected.     

Improving efficiency of organic light-emitting devices by optimizing the LiF interlayer in the hole transport layer

The efficiency of organic light-emitting devices (OLEDs) based on N,N'-bis(1-naphthyl)-N,N'-diphenyl-N,1'-biphenyl-4,4'-diamine (NPB) (the hole transport layer) and tris(8-hydroxyquinoline) aluminum (Alq₃) (both emission and electron transport layers) is improved remarkably by inserting a LiF interlayer into the hole transport layer. This thin LiF interlayer can effectively influence electrical performance and significantly improve the current efficiency of the device. A device with an optimum LiF layer thickness at the optimum position in NPB exhibits a maximum current efficiency of 5.96 cd/A at 215.79 mA/cm², which is about 86% higher than that of an ordinary device (without a LiF interlayer, 3.2 cd/A). An explanation can be put forward that LiF in the NPB layer can block holes and balance the recombination of holes and electrons. The results may provide some valuable references for improving OLED current efficiency.     

Highly stable carbon-doped Cu films on barrierless Si

Electrical resistivities and thermal stabilities of carbon-doped Cu films on silicon have been investigated. The films were prepared by magnetron sputtering using a Cu-C alloy target. After annealing at 400 °C for 1 h, the resistivity maintains a low level at 2.7 μΩ-cm and no Cu-Si reaction is detected in the film by X-ray diffraction (XRD) and transmission electron microscopy (TEM) observations. According to the secondary ion mass spectroscopy (SIMS) results, carbon is enriched near the interfacial region of Cu(C)/Si, and is considered responsible for the growth of an amorphous Cu(C)/Si interlayer that inhibits the Cu-Si inter-diffusion. Fine Cu grains, less than 100 nm, were present in the Cu(C) films after long-term and high-temperature annealings. The effect of C shows a combination of forming a self-passivated interface barrier layer and maintaining a fine-grained structure of Cu. A low current leakage measured on this Cu(C) film also provides further evidence for the carbon-induced diffusion barrier interlayer performance.     

Interlayer Exchange Coupling Across Quasi-Amorphous Ti-Co and Zr-Co Spacers

Co/Ti and Co/Zr multilayers with wedge-shaped and constant-thickness Ti and Zr sublayers were prepared using UHV DC/RF magnetron sputtering. Results showed that the Co sublayers are ferromagnetically coupled up to Ti and Zr spacer thickness of about 1.9 and 2.4 nm, respectively. Furthermore, a weak antiferromagnetic coupling of the Co sublayers was observed for a Ti (Zr) thickness range between 1.9 and 2.7 nm (2.4 and 3.2 nm). The Co sublayers are very weakly exchange coupled or decoupled for d _Ti 2.7 nm and d _Zr 3.2 nm. The rapid decrease of the interlayer exchange coupling could be explained by its strong damping due to formation of a non-magnetic quasi-amorphous Ti-Co and Zr-Co alloy layer at the interfaces.     

Fabrication of nitrogen-doped TiO2 layer on titanium substrate

In this paper, macropores TiO₂ layer was fabricated on titanium substrates based on plasma based ion implantation (PBII). In order to increase the photodegradation efficiency of fabricated TiO₂ layer, two approaches are used: (1) preparation of macropores on TiO₂ layer to increase the total photodegradation area and (2) nitrogen doping (N-doping) to increase light absorption efficiency. The fabrication process of the N-doped macropores TiO₂ layer comprises four steps: firstly, helium plasma based ion implantation (He-PBII) is employed to generate He bubbles in substrate; secondly, oxygen plasma based ion implantation (O-PBII) and a followed annealing in air are executed to obtain rutile and anatase mixture TiO₂ phases; thirdly, He bubbles are exposed to the surface via an Ar ion sputter process; lastly, the samples are doped by nitrogen PBII (N-PBII). The photodegradation of Rhodamine B solution under Xe lamp indicates that the TiO₂ layer with surface macropores and N-doping has higher light photocatalysis efficiency.     

Composition and structure of coatings formed on a VT16 titanium alloy by electro-plasma spraying combined with microarc oxidation

The composition, the structure, and the microhardness of the oxide coating formed during a combined plasma process on a VT16 titanium alloy are studied. The structure of plasma-sputtered aluminum oxide after microarc oxidation is found to change: the coating has a lower density and is melted. The phase composition of the aluminum oxide formed by electro-plasma sputtering and then subjected to microarc oxidation remains unchanged.     

Release studies of corrosion inhibitors from cerium titanium oxide nanocontainers

Cerium titanium oxide nanocontainers were synthesized through a two-step process and then loaded with corrosion inhibitors 2-mercaptobenzothiazole (2-MB) and 8-hydroxyquinoline (8-HQ). First, polystyrene nanospheres (PS) were produced using polymerization in suspension. Second, the PS spheres were coated via the sol–gel method to form a cerium titanium oxide layer. Finally, the nanocontainers were made by calcination of the coated PS nanospheres. The size of the containers was 180 ± 10 nm as determined by Scanning Electron Microscopy (SEM). X-Ray Diffraction Analysis (XRD) showed that the nanocontainers consist of anatase and cerianite crystalline phases. The presence and loading of the inhibitors in the nanocontainers was confirmed with Fourier Transform Infrared Spectroscopy (FT–IR) and Thermo Gravimetric Analysis (TGA), respectively. TGA revealed the amount of 10.43 and 4.61% w/w for 2-MB and 8-HQ in the nanocontainers, respectively. Furthermore, the release kinetics of the inhibitors from the nanocontainers was studied in corrosive environment using electrochemical impedance spectroscopy (EIS) in the presence of aluminum alloys 2024-T3 (AA2024-T3).     

The surface composition of the gold-palladium binary alloy system

The surface composition of the AuPd alloy system has been determined by Auger electron spectroscopy. Measurements were performed on polished polycrystalline alloy foils. After cleaning, the intensities of the 71 eV and 2024 eV gold Auger transitions, and the intensity of the 330 eV palladium transition were measured, and then converted to atom concentrations in the surface layer. The surfaces of the annealed samples were found to be significantly enriched in gold with respect to the bulk. This result disagrees with the regular solution theory prediction. After extensive sputtering of the AuPd alloys with 1.5 keV Ar⁺ ions, a slight surface enrichment with palladium was found, as predicted by the simple theoretical model for sputtering.     

A15Nb3Si produced by high-pressure annealing of amorphous sputter deposits

A high-pressure annealing technique has been used to convert an amorphous Nb-23.7 at.% Si alloy, prepared by sputtering, into the A15 phase alloy. X-ray diffraction examination of the alloy samples quenched to ambient conditions has shown that they are in an almost single-phased state with a lattice parameter of 0.5120 nm and a high degree of atomic ordering. An onset of superconductivity has been detected at 8.9 K and a temperature derivative of upper critical field is 14 kOe/K (MA/4π mK).