Aluminium substrates

Pig. 2. (a) The cell mount design of the integrated PV array of Pigure 1, which uses laminated conductive and insulating layers on top of an aluminium substrate in a printed circuit board-type panel (7). The array produces 20 kW at 20°C ambient and 850 W/m direct sunlight, and measures 155 m. The lens is a molded acryUc Presnel lens parquet mounted on the front of the array stmcture. The PV panel is mounted on the back of the array stmcture and is... 

P.V.D.F. Polyvinylidene fluoride (p.v.d.f. or p.v.f.2) dispersions are applied by the coil-coating process. They are blends of p.v.d.f. resin and acrylic. The combination produces a system which has excellent weather-ability and which can be bonded via an adhesive primer to a galvanised steel or aluminium substrate. 

Figure 3.7 DMTA spectrum for an alkyd paint film attached to an aluminium substrate, Tg = 43.5 °C...

Equation (4.4) stresses that the surface plasma wave propagates within the aluminium substrate whose frequency is modified by the dielectric response of the molecular adlayer. From the measurements reported, with hcog = 8.5 eV and hcob = 15 eV, one obtains e = 2.1 for CuPc, a value in agreement with those measured for other planar organic molecules, with an extended delocalization of 7T-electrons (Alonso et al, 2003). 

The appearance of the optical absorption bands (Q and B) has a clear threshold at a low non-zero coverage, implying that the electronic structure of the first adsorbed molecules is different from that of the bulk ones. Thus, a clear distinction between molecules directly bonded to the aluminium substrate d- < 0.3 run) and molecules not directly bonded to the substrate d- >0.3 nm) can be made. In the latter case the electronic structure, as revealed by EELS, is identical to that of bulk CuPc, while in the former case modification of the electronic structure prevents transitions toward the LUMO orbital. Above 1.0 nm the Q and B band intensities saturate. The optical transitions are inhibited for molecules directly bonded to the alumiiuum substrate... 

The high electrical resistivity of aluminum oxide is believed to be the major reason why coatings continue to exhibit very strong adhesion to aluminium substrates even when localized corrosion is observed to occur. Therefore, by developing a pretreatment process for any metal substrate which produces a metal oxide with high electrical... 

HPC (Klucel E5, Hercules hydroxypropyl molar substitution, MS-3) and HPMC (Methocel E15, Colorcon hydroxypropyl molar subsitution, MS-0.23s degree of methoxyl substitution DS-1.88) were studied as a thin film of approximate thickness of 5-10 urn cast from an aqueous solution onto a clean aluminium substrate and allowing the solvent to evaporate. Scanning electron microscopy of films prepared in this manner revealed a continuous surface free from cracks and aberrations. 

In the following, we present two examples related to analysis of the mechanical stability of CVD films on substrates. One case describes systems intended for microelectronic devices (passivation films on a aluminium substrate), and the other describes coatings intended for wear and corrosion protection of steels. 

The fullerenes used were synthesized according to the electric arc method, giving a mixture of Qo and C o in the ratio —85 15. Thin films of the fullerene-doped polymer are prepared by spin-coating fullerene and PVK (molecular weight —5x10 ) from solution in toluene (typically 40 mg of fullerene and 1.5 g of PVK in 12 ml of toluene) onto aluminium substrates. The samples are dried in an oven at 100 °C for several hours before use. The film thickness can be varied from 1 to 30 xm, by changing the concentration of PVK and the spin speed. The films are optically clear and air-stable for at least several months. 

Xerography The high electrical resistivities and optical absorptivities of chalcogenides have lead to many important applications. One of the most remarkable applications is in xerography (dry writing). The principle involved is simply as follows (i) Se film coated on an aluminium substrate is exposed to corona discharge in order to charge the selenium... 

Ca(OH)2, respectively. The mechanical properties of the deposits such as critical load, scratch hardness and friction coefficient were determined by scratch testing under loads of 3-9 N. The coatings sprayed onto titanium alloy indicated critical load of 12.3 N and the ones onto aluminium substrate were lower and equal to 10.5 N. 

A study aimed at devising a strategy to optimise the properties of Ti02 coating deposited by SPS onto aluminium substrates was performed by Jaworski et al. 

Figure 2. SEM images of an anodicaUy oxidized and roughened aluminium substrate. Top view (a), tilted (35 ) and magnified image (b), and pobshed cross-section (c).

Fig. 4. Auger depth profile of an anodized aluminium substrate. The oxide is approximately 300-nm thick...

Fig. 2. RAIR spectra of plasma-polymaized siUca-like films deposited onto aluminium substrates for diffoent times and thus at diffaent thickness. Copyright (2002) from (Journal of Adhesion) by (F. J. Boaio). Reproduced by permission of Taylor Francis, Inc., http //www.taylorandfrancis.com...

The more common environmental problem with metal joints is attack by water. In addition to alloy composition, pre-treatment and primer, durability is affected by the adhesive used (see Pre-treatment of metals prior to bonding. Pre-treatment of polymers. Primers for adhesive bonding). Sell has ranked adhesives in the order of durability they provide with aluminium substrates ... 

In the alkaline solutions (pH 10) on flat aluminium substrate globular powders of silver were produced (a), while in acidic solution (pH 2) dendritic stmctures are observed (b). 

The production of silver powder from an acidic solution using the aluminium substrate can be explained by the following reaction ... 

Heimann, R.B., Pentinghaus, H.J., and Wirth, R. (2007) Plasma-sprayed 2 l-mullite coatings deposited on aluminium substrates. Eur. J. Mineral, 19, 281-291. 

Aluminium substrates are frequently pre-treated by anodic oxidation to generate a porous surface, which may serve as the catalyst support itself or as an adhesion layer for a catalyst support [122]. The surface area of the obtained alumina layer may reach 25 m g , with a thickness of 70 pm or higher. Assembled alumina micro-channel reactors can also be oxidised. The layer generated by anodic oxidation of aluminium and aluminium alloys is amorphous hydrated alumina. It is believed to contain boehmite, pseudoboehmite and physically adsorbed water [123]. It has the morphology of a packed array of hexagonal cells, each containing a pore in the centre. Thus the layer has a highly ordered porous structure and uniform thickness, when an... 

However, this nature oxide film does not offer sufficient protection against aggressive anions and dissolution of aluminium substrate occurs when exposed to corrosive solution. 

Seawater predominantly consists of about 3.5% of sodium chloride (NaCl) and many other ions. Chloride ions are very strong and could easily penetrate the passive film Thus, dissolution of the aluminium substrate occurs and results in corrosion. The adsorption of the corrosion inhibitor competes with anions such as chloride. By assuming that the corrosion inhibitor molecules preferentially react with Al - to form a precipitate of salt or complex on the surface of the aluminum substrate, the anodic and cathodic processes subsequently suppressed by inhibitor molecules. Thus, this result suggests that the protective film that was formed comprise aluminium hydroxide, oxide and salts or complexes of the corrosion inhibitor anions. 

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