Coatings main requirements

Two-pack epoxy Section 12.3.3. These are widely used to give the maximum protection to concrete surfaces, floors and walls. They can be applied as relatively thin coatings by spray or as thick epoxy surfaces applied by trowel. In all cases, the application must be preceded by adequate surface preparation (see Section 12.6.1). To allow maximum penetration into the concrete the first coat must have a low viscosity. Coal tar epoxies are used where protection is the main requirement. 

The finish This coat is required to provide all decorative properties (colour and gloss) and the main resistance to external damage (e.g. u.v. degradation). 

The main requirements for a coating are that it is easy to apply (i.e., low viscosity) and dries to a non-tacky finish within a reasonable time. Originally, this equated to the solution and evaporation of the solvent. However, because of environmental concerns, formulations have tended to shift the concentration of solvents from 80% to less than 20% (known as high solids coatings). Many industrial processes use polymer powders (of approximately 40 pm diameter),... 

Burners. The main requirements for commercial burners are the maintenance of a large safety factor and ability to pass solutions of highly dissolved solids without blockage. Usually acidic solutions are prepared for the AA analysis, which means that burners are made from stainless steel or titanium in order to avoid corrosion. Also the inner surfaces of the burner shell are coated with an inert plastic material, like poly (phenyl sulfide). 

Winchester discs are molded as blanks in engineering plastics, usually General Electric s Ultem polyetherimide, then coated with an epoxy-ferric oxide layer. The main requirement in manufacturing these discs is absolute flatness because the magnetic read/write head moves only 8-20 microinches above the disc surface and is spinning at a high speed of 3,600 rpm. Any microscopic bump can thus cause damage to both the disc and head. 

The properties of coating systems used for car components differ considerably from those of systems used for exterior car surfaces. Color is not important (and is mainly black or gray), but anticorrosive properties similar to those of car body coatings are required. Since car components are produced in large numbers, coatings are commonly baked at high temperature to ensure a high reaction rate and rapid film formation. 

The painting areas of a ship are shown in Figure 11.1. The main requirement of marine coating systems is corrosion prevention. Detailed requirements vary with the particular internal or external area (e.g., chemical resistance in cargo tanks resistance to seawater in ballast spaces heat resistance in engine rooms impact and abrasion resistance on boottoppings, external hulls, and decks cosmetic qualities on superstructure and topsides). 

Application of coatings to FRP exposed top surfaces, i.e. those not in contact with a mould, may be required for similar reasons to using gel coats. These flow coats mainly differ in their method of application and consolidation. Flow coats should be applied if possible when the exposed surface is still at the green stage in order to obtain the highest adhesion if similar materials are being used to the main resin system. Adhesion to time-delayed exposed FRP surfaces can be low and considerable additional effort may be required in surface preparation to attain the required bond strengths. 

The main requirements for coatings are dnrability, opacity, gloss, adhesion to snbstrate, colour, protection, and specific physical properties. Dnrability is considered as the degree to which surface coating systems withstand the destructive effects of the environment which can involve weathering as well as mechanical wear and attack by corrosive substances [57, 58]. 

The pultruded part is evaluated by ultrasonic C-scan or ir scanning. Uniform fiber dispersion and even coating by the matrix resin are the main requirements. 

The concentrations of UV absorbers usually used in engineering thermoplastics cover a range of 0.1 to 5% [529]. High concentrations up to 10% are mainly required in multi-layer coatings. 

Electrical and/or thermal conductivities are the main requirements in these types of adhesives, and conductive (metalHc or metal coated) fillers are used for this purpose. Most fillers that... 

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