Aluminium metallizing plastic

Aluminium overcaps may have a perforated metal, plastic fhp-off or peelable foil cover. Figure 6.21 shows typical combination and conventional seals. Vials have also been introduced for unit dose packs using either an aluminium two-piece tear-off closure with a Saran coated pulpboard liner or a peel-type seal. 

In the quest for the ideal adhesive system to suit an application needs, it is essential to understand the effect of the silicone properties on the mechanisms of Silicone adhesion. The primary requirement for good adhesion is the creation of an intimate interface through Wetting and spreading of the silicone onto the substrate. The low surface tension and viscosity range of silicones satisfy this necessary condition. Therefore, the mechanical mechanism of adhesion is operative and plays a key role in adhesion of silicones to many different substrates such as leather, textile fabrics, porous metals like anodized aluminium, porous plastic and composite materials, and specialty papers like glassine, super calendered kraft and clay-coated papers. 

Gotzmann [60] discusses methods used in the manufacture of metal plastic hybrid components such as glass fibre reinforced PA around a steel or aluminium profile placed in the mould used for injection moulding plastics. Some applications of such components were examined, and computer aided materials selection, finite element analysis and computer simulation systems developed for use in this technology are described. 

A wide range of metal, plastic and ceramic porous sheets and tubes are available for use in filbation processes. Of particular interest are metal fibre webs such as the Bekipor range manufactured by Bekaert in Belgium which are available in 316L stainless steel, Inconel 601 or Hastelloy X, and metal media produced by sintering bronze, stainless steel, nickel. Monel, Hastelloy, Inconel, titanium, aluminium or tantalum. 

Acrylic lacquers are used both as basecoats and topcoats in vacuum metallising applications on a number of plastic substrates, including polyester, nylon, acrylic, polyethylene, polystyrene and PVC. The function of the basecoat is to provide a good key between the substrate and the vaporised aluminium metal and to fill the imperfections in the substrate, thus enhancing the brightness and reflectivity of the deposited metal. The basecoat must also have extremely low volatility, since volatile by-products released under vacuum would lead to a poor quality deposition. The fast lacquer drying properties of acrylics and the non volatile inert nature of the polymer film make them an ideal choice for this application. 

CoiTosion prevention is achieved by correct choice of material of construction, by physical means (e.g. paints or metallic, porcelain, plastic or enamel linings or coatings) or by chemical means (e.g. alloying or coating). Some metals, e.g. aluminium, are rendered passive by the formation of an inert protective film. Alternatively a metal to be protected may be linked electrically to a more easily corroded metal, e.g. magnesium, to serve as a sacrificial anode. 

Any common metal or plastic Mild steel, aluminium, brass, or stainless steel Iron and steel... 

PVC, polythene and PTFE if moist gas is used Stainless steel, copper, nickel. Monel, brass, aluminium for dry gas <200°C. Borosilicate glass for low pressures. For moist gas, copper and polyvinylidene chloride plastics Monel and nickel Monel and nickel Most common metals so long as gas is dry... 

Most common metals Mild steel, aluminium, brass, copper or stainless steel Any common metal Any common metal Iron, steel, copper, brass, plastic for dry gas. For moist gas use stainless steel or certain plastics Copper-lined metals for... 

Many thermoplastics are now accepted as engineering materials and some are distinguished by the loose description engineering plastics. The term probably originated as a classiflcation distinguishing those that could be substituted satisfactorily for metals such as aluminium in small devices and structures from those with inadequate mechanical properties. This demarcation is clearly artificial because the properties on which it is based are very sensitive to the ambient temperature, so that a thermoplastic might be a satisfactory substitute for a metal at a particular temperature and an unsatisfactory substitute at a different one. 

This type consists of a propeller or disk-type wheel within a mounting-ring panel or cage. The wheel or housing is constructed from either sheet metal, cast aluminium, plastic, or plastic-coated material. It may be a direct drive with the wheel on the motor shaft or belt driven. 

Ducts of other materials than metal sheet (plastic, glass fiber wool and aluminium sheet, ceramics, glass, etc.)... 

Plastics are generally without action on aluminium and are widely used to provide insulation between other metals and aluminium, while the use of aluminium/plastic laminates is increasing. Rubber has no effect upon aluminium. 

In the 1970s and 1980s alloys with higher contents of aluminium have become more important, especially for casting using metal or graphite moulds. Table 4.30 has been modified to cover these alloys. A super-plastic alloy containing about 22% aluminium has also been developed, but only has very limited use. 

For some purposes where the strength and ductility of steel are not prerequisites, other metals or materials may be used to advantage, particularly when the component or article is not a load-bearing one. Some of the non-ferrous metals and plastics materials are extremely useful in this respect, especially the latter with their excellent corrosion-resistant properties and ease of formability. Non-ferrous metals in sheet form are often used as roof covering. In such situations they could well become subject to condensation. Condensation could be the result of thermal pumping or internal conditions. Under conditions in which condensation can occur, copper is not normally attacked, but lead, zinc and aluminium may be attacked and corrode from the inside of the building outwards. 

Sprayed, vacuum-deposited and plated coatings can be applied to most metals and to many non-metals, e.g. vacuum deposition is applied to many substrates including plastics spray application can be used for coating fabric, plastic and paper. Hot dipping and other diffusion processes are dependent on the nature of the substrate for the properties of the coating. Most commercial applications of aluminium coatings are on iron and steel with smaller quantities applied to aluminium alloys and plastics. 

Access of air and water will also affect the corrosion rate. Metal inserts in corrosive plastics are most actively attacked at the plastic/metal/air interfaces with certain metals, notably aluminium titaniumand stainless steel, crevice effects (oxygen shielding and entrapment of water) frequently accelerate attack. Acceleration of corrosion by bimetallic couples between carbon-fibre-reinforced plastics and metals presents a problem in the use of these composites. 

The interior surface finish, to comply with EEC and other health standards, must be rustproof, cleanable, and free from any crevices which can hold dirt. Bare timber in any form is not permitted. Most liners are now aluminium or galvanized steel sheet, finished white with a synthetic enamel or plastic coating. GRP liners are also in use. Floors are of hard concrete or tiles. Very heavy working floors may have metal grids let into the concrete surface. Floor concrete is coved up at the base of the walls to form a protective curb. 

The current (2003) edition of PD 5500 covers vessels fabricated in carbon and alloy steels, and aluminium. The design of vessels constructed from reinforced plastics is covered by BS 4994. The ASME code covers steels, non-ferrous metals, and fibre-reinforced plastics. 

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