Aluminum layer

It should be noted that a number of aluminum alloys are available (see Table 28-16). Many have improved mechanical properties over pure aluminum. The wrought heat-treatable aluminum alloys have tensile strengths of 90 to 228 MPa (13,000 to 33,000 Ibf/in ) as annealed when they are fuUy hardened, strengths can go as high as 572 MPa (83,000 Ibf/in"). However, aluminum alloys usually have lower corrosion resistance than the pure metal. The alclad alloys have been developed to overcome this snortcoming. Alclad consists of an aluminum layer metaUurgicaUy bonded to a core alloy. 

In Figure 5-12 is a set of core level spectra shown, which have been recorded between successive steps during the growth of an aluminum metallic overlayer on top of PPV [59]. The thickness of the aluminum layer for the lowest and highest coverage correspond to 2 and 20 A, respectively. 

Figure 5-11. XPS core level spccira recorded during successive removals of ihe aluminum layer oil PPV (adapted from 1551).

Assuming axi-symmetrical deformation, simulation of the complete micromirror surface has been found to have a "palm-tree" shape, with t5q)ical maximum deformation less than 2 nm. This shape can be explained by strain relaxation in the thin aluminum layer constituting the mirror surface (Zamkotsian and Dohlen, 1999). 

The Alclad alloys have been developed to overcome this shortcoming. Alclad consists of a pure aluminum layer metallurgically bonded to a core alloy. The corrosion resistance of aluminum and its alloys tends to be very sensitive to trace contamination. Very small amounts of metallic mercury, heavy-metal ions, or chloride ions can frequently cause rapid failure under conditions which otherwise would be fully acceptable. When alloy steels do not give adequate corrosion protection—particularly from sulfidic attack—steel with an aluminized surface coating can be used. 

The result was the compact disc (CD). Made from 1.2 mm of polycarbonate plastic, the disc is coated with a much thinner aluminum layer that is then protected with a film of lacquer. The lacquer layer (10) can be printed with a label. CDs are typically 120 mm in diameter, and can store about 74 minutes of music. There are also discs that can store 80, 90, 99, and 100 minutes of music, but they are not as compatible with various stereos and computers as the 74—minute size. 

H Aziz, Z Popovic, S Xie, A-M Hor, N-X Hu, C Tripp, and G Xu, Humidity-induced crystallization of tris(8-hydroxyquinoline) aluminum layers in organic light-emitting devices, Appl. Phys. Lett., 72 756-758, 1998. 

Injection molding requires the barrel temperature to be about 350°C with a barrel pressure in excess of 138 MPa. The mold is maintained at 110°C to ensure uniform flow and high definition, and to discourage an uneven index of refraction, birefringence. The CD is about four one-hundredths of an inch (0.5 mm) thick. For prerecorded CDs, the PC is compression-molded on a stamper imprinted with the recorder information. This takes about 4 sec. Once the clear piece of polycarbonate is formed, a thin, reflective aluminum layer is sputtered onto the disc. Then, a thin acrylic layer is sprayed over the aluminum to protect it. The label is then printed onto the acrylic surface and the CD is complete. This process is described later in greater detail. 

GP[2] zones, or two Cu 001 layers separated by a few aluminum layers, have also been observed in the field ion microscope in an aged Al-4 wt% Cu alloy.71 A GP[2] zone formed on the (200) plane and observed on the (022) surface of the [001] oriented tip can be observed as two rows of bright image spots if an odd number of the (200) atomic layers are present between the Cu layers. The imaging condition at the (022) surface is more complicated if an even number of the (022) layers are present... 

The simplest recording medium is a bilayer structure. It is constructed by first evaporating a highly reflective aluminum layer onto a suitable disk substrate. Next, a thin film (15-50 nm thick) of a metal, such as tellurium, is vacuum deposited on top of the aluminum layer. The laser power required to form the mark is dependent on the thermal characteristics of the metal film. Tellurium, for example, has a low thermal diffusivity and a melting point of 452 °C which make it an attractive recording material. The thermal diffusivity of the substrate material should also be as low as possible, since a significant fraction of the heat generated in the metal layer can be conducted to the substrate. For this reason, low cost polymer substrates such as poly (methylmethacrylate) or poly (vinyl chloride) are ideal. 

A 5.5 (xm photoresist layer was patterned as the sacrificial layer, followed by the deposition of a second 4.5 p,m parylene layer. The parylene/photoresist/ parylene sandwich structure formed the electrospray nozzle and channel when the photoresist was subsequently dissolved. A 1500 A sputtered aluminum layer was used as a mask for parylene etching to define the shape of the nozzle. Aluminum was removed by a wet etching process. After SU-8 developing, wafers were left inside the SU-8 developer for 2 days to release the photoresist. A serpentine channel (250 pan x 500 pm x 15 mm) extending from the junction of pump channels to the edge of the chip was patterned in the SU-8 layer. Platinum/titanium lines spaced 200 pm apart were patterned under the channel after the electrode deposition step. 

A practical unit of detector is composed of a silicon wafer, an indium foil of 0.5 mm thick and a substrate of machinable glass. The indium foil makes electric contact with the aluminum layer on the wafer. The dimensions of the wafers and the substrates are as follows ... 

The Al(2p) spectra for aluminum on P30T, as a function of the coverage, are shown in Fig. 7.4. These spectra exhibit two interesting features. First, the main Al(2p) line gradually shifts towards lower binding energy as the thickness of the aluminum layer increases. This is a consequence of the improved core-hole screening for... 

In this protocol we describe an electroplating procedure for mild steel with an adhesive aluminum layer in Lewis acidic ionic liquid l-ethyl-3-methylimidazolium chloride [EMIMJC1 containing AICI3. We aim to electroplate mild steel with dense, adherent and uniform aluminum layers in the employed ionic liquids at room temperature. 

The SEM micrograph of Figure 12.1 shows the surface morphology of an electroplated aluminum layer obtained at a current density of—20mAcm-2 for 2h in Lewis acidic [EMIMJCl/AlClj at room temperature on mild steel. As can be seen, the obtained A1 deposit consists of coarse crystallites forming rather a compact layer without observable cracks. 

The SEM micrograph of Figure 12.7(a) shows the surface morphology of a deposited aluminum layer obtained galvanostatically at a current density of—5 mAcrn-2 for 2h in the upper phase of the biphasic mixture [EMIM] TFSA/6M AICI3 at room temperature. Prior to Al electrodeposition, the electrode was anodically polarized at a potential of 1V (vs. Al) for 2 min. As seen, the deposited Al layer is dense and contains crystallites in the micrometer regime. 

Figure 12.8 shows the photo of a deposited aluminum layer obtained potentio-statically on a mild steel substrate at -0.3 V (vs. Al) for 4h in the upper phase of the mixture [EMIM] TFSA/6 M AICI3. The substrate was electrochomically etched at 1V (vs. Al) for 2 min prior to electrodeposition. The aluminium layer adheres so well that it can be mechanically polished to a mirror appearance. 

Eidmann K, Andiel U, Pisani F, Hakel P, Mancini RC, Junkel-Vives GC, Abdallah Jr. J, Witte K (2003) K-shell spectra from hot dense aluminum layers buried in carbon and heated by ultrashort laser pulses. J. Quant. Spectrosc. Ra. 81 133-146... 

For this reason the consumable anodes must be replaced periodically. The cathode consists of a molten aluminum layer on the bottom of the cell, and the anode-cathode distance is 4-5 cm. Alumina is periodically added to the cell in the proportion that it is consumed by electrolysis. The electrode processes during aluminum electrolysis are very complex [141] and a proper understanding of these processes is important because of the economic implications energy and carbon consumption, cell control, pollution of the environment, etc. 

Another very important group of materials, the clays, are formed from silicon-oxygen sheets. In this case, however, the sheet is not the simple one shown in Fig. XXVI-4, but each sheet is bound by homopolar valences to another sheet of different composition. For instance, in kaolinite, one form of clay, one starts with a silicon-oxygen sheet. Above that, there is an aluminum layer, with as many aluminums as silicons, bonded to the oxygens. The other bonds of the aluminums extend to a... 

Chisem, I. C. and Jones, W. (1994). Ion-exchange properties of lithium aluminum layered double hydroxides. J. Mater. Chem. 4, 1737. 

Boclair, J. W., Braterman, R S., Brister, B. D. and Yarberry, F. (1999). Layer-anion interactions in magnesium aluminum layered double hydroxides intercalated with cobalticyanide and nitroprusside. Chem. Mater. 11, 2199. 

Metallized polymers are used nowadays in numerous industrial applications (food packaging, capacitors, magnetic tapes etc...). The adhesion and the durability of metal/polymer systems represent the most important concepts that concern many research groups (1-3). Obviously, any aggressive medium which corrodes the metal film will be directly related to some loss of adhesion and durability. The aim of this work is to investigate the influence of corrosive environments on aluminum layers evaporated onto PET film and especially on both the A1 surface and interface. 

Two kinds of morphology have been found in the specimens observed by cross-section TEM. The aluminum films evaporated on the control film and the corona treated film have the usual "Rod Like structure (RLS) morphology whilst on the fluorine treated film the aluminum layer presents a " Non Rod Like structure" (NRLS) i.e. the grain boundaries are not crossing the full thickness of the metallic layer. A schematic representation of both morphologies is shown in figure 2. 

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