Industrial protective coatings

Furane resins are generally used in the manufacture of molding materials, adhesives, and impregnating varnishes. As an acid- and alkali-proof cement, they are extensively used as bonding media for chemical stoneware in the processing industries. Protective coatings have been developed for imparting chemical resistance to surfaces subject to attack. 

Industrial protective coatings cover heavy duty, maintenance and marine systems including coatings for structural steel, ships, tanks, off shore installations, mining, oil and gas pipelines and refineries. 

Commercially available acrylics suitable for industrial protective coatings include ... 

The naturally occurring isomer, a-licanic acid, has m.p. 74-75" C. It is unstable, and is readily isomerized to the / -form, m.p. 99-5 C. It occurs in oiticica and other oils which were previously used in the protective-coating industry. 

The importance of polymer composites arises largely from the fact that such low density materials can have unusually high elastic modulus and tensile strength. Polymers have extensive applications in various fields of industry and agriculture. They are used as constructional materials or protective coatings. Exploitation of polymers is of special importance for products that may be exposed to the radiation or temperature, since the use of polymers make it possible to decrease the consumption of expensive (and, sometimes, deficient) metals and alloys, and to extent the lifetime of the whole product. 

These foams are used for board stock in commercial and industrial buildings as insulation for internal cavity and external walls, roof, floor, and foundations. Spray-appHed foam, covered subsequently with one of a variety of protective coatings, is widely used for large roofing appHcations and has limited use as external walls. Eor residential buildings, the principal use is as external sheathing board. 

Unilver Table 1. Worldwide 1992 Electronics Industry Value/ x 10 adhesives, dielectric coatings, protective coatings, dielectric interlayers, electronic functional coatings... 

Zinc is often used as a protective coating over iron to form galvanized iron. In industrial settings exposed to SOj and humidity, this zinc coating is subject to sufficient corrosion to destroy its protective capacity. Haynie and Upham (5) used their results from a zinc corrosion study to predict the useful life of a zinc-coated galvanized sheet in different environmental settings. Table 9-2 shows the predicted useful life as a function of SO concentration. 

Thin polymeric films have important industrial apphcations (e.g., as protective coatings, lubricants, adhesives, dielectric or nonlinear optic devices, etc.) and pose many fundamental problems of film stability [1,2,4]. An important question, therefore, is whether these films break up and spontaneously dewett the substrate, resulting in the formation of droplets. The... 

Marine and industrial atmospheres (without the use of protective coatings), because of high corrosion rates ... 

The corrosion resistance of zinc is discussed in Section 4.7, and it is only necessary here to say that zinc is protected against further attack by a film of corrosion products. It is remarkably resistant to atmospheric corrosion except perhaps in the most heavily contaminated industrial areas, and even there its use as a protective coating is still a sound practical and economic proposition. The value of zinc coatings as a basis for painting under very aggressive conditions has been clearly demonstrated. 

Chromate treatments can be applied to a wide range of industrial metals. They are of two broad types (a) those which are complete in themselves and deposit substantial chromate films on the bare metal and (b) those which are used to seal or supplement protective coatings of other types, e.g. oxide and phosphate coatings. Types of treatment for various metals are summarised in Table 15.16. 

Galvanic current Measurement of the galvanic current between two different metals can be easily measured using a zero resistant ammeter ". This method can have specific application, e.g. to provide a signal indicating failure of a protective coating in a process vessel. Commercial probes are available for industrial monitoring. 

Tin finds widespread use because of its resistance to corrosion, or as foil or to provide protective coats/plates for other metals. Properties of lead which make industrial application attractive surround its soft, plastic nature permitting it to be rolled into sheets or extruded through dies. In the finely-divided state lead powder is pyrophoric in bulk form the rapidly-formed protective oxide layer inhibits further reaction. It dissolves slowly in mineral acids. Industrial uses include roofing material, piping, and vessel linings, e.g. for acid storage. 

Catalysts were expensive, however, so the petroleum industry did not solve the problem of cheap, lead-free, knock-free gasoline until the 1970s, after General Motors adopted the catalytic converter. Lead compounds inactivate the catalysts, and sophisticated catalytic cracking techniques had to be developed to replace the fuel additive. Ironically, an even more difficult job was finding a substitute for the protective coating that tetraethyl lead formed on exhaust valve seats not even newly developed, extremely hard materials prevent wear and tear on them as well as tetraethyl lead did. 

---