Specialized Coatings

In reality, aircraft parts can consist of several stacked layers of material, eonnected by rivets or bolts. To avoid corrosion, the layers are often protected by a special coating, so that there is no electrical connection between the layers. If there is a crack for example in the middle layer, no current will thus flow above or below the defect because of the insulating coating between the layers. There is only the possibility for the current to flow around the crack in the x-y... 

The shipment of many commodities may require special barriers on the sacks to impart resistance against hquids or vapors. Other treatments are used to provide grease resistance, acid resistance, and scuff resistance. Special coatings are used in sacks for packing commodities, eg, synthetic mbbers, asphalts, waxes (qv), and resins, to prevent the contents from sticking to the paper. 

Random copolymers of vinyl chloride and other monomers are important commercially. Most of these materials are produced by suspension or emulsion polymerization using free-radical initiators. Important producers for vinyl chloride—vinyUdene chloride copolymers include Borden, Inc. and Dow. These copolymers are used in specialized coatings appHcations because of their enhanced solubiUty and as extender resins in plastisols where rapid fusion is required (72). Another important class of materials are the vinyl chloride—vinyl acetate copolymers. Principal producers include Borden Chemicals Plastics, B. F. Goodrich Chemical, and Union Carbide. The copolymerization of vinyl chloride with vinyl acetate yields a material with improved processabihty compared with vinyl chloride homopolymer. However, the physical and chemical properties of the copolymers are different from those of the homopolymer PVC. Generally, as the vinyl acetate content increases, the resin solubiUty in ketone and ester solvents and its susceptibiUty to chemical attack increase, the resin viscosity and heat distortion temperature decrease, and the tensile strength and flexibiUty increase slightly. 

Uniform corrosion is the deterioration of a metal surface that occurs uniformly across the material. It occurs primarily when the surface is in contact with an aqueous environment, which results in a chemical reaction between the metal and the service environment. Since this form of corrosion results in a relatively uniform degradation of apparatus material, it can be accounted for most readily at the time the equipment is designed, either by proper material selection, special coatings or linings, or increased wall thicknesses. 

Anodic Metallic Coating—a special coating usually comprised, either entirely or in part, of an anodic metal, which is electrically positive to the substrate to which it is applied. 

For the examination of paint films or special coatings, e.g. pipe linings, low-voltage holiday detectors with wet sponge electrodes are available. 

Figure 8. One-gallon, high density polyethylene bottle used for cooking oil. A special coating on the exterior preserves freshness by excluding oxy-...

It is important not to chew capsules before swallowing they must be swallowed whole. The patient also should not chew tablets unless labeled as chewable. Some tablets have special coatings that are required for specific purposes, such as... 

Special coating for maximum chemical resistance. Intermediate layer for tool steel coatings. 

First prototypes have been built of separate water cooled exchanger plates, based on polypropylene double plates, which have been developed and tested within the last years. Since 1997 the tests has shown very satisfying results. A special coating of the plates and a special solution distribution element (no sprays are used) provide a uniform and almost complete coverage of the surface by the solution. 

The metallurgy selected for construction of a firewater pump is dependent on the properties of the water source to be used. For fresh water sources (i.e., public water mains), cast iron is normally adequate although bronze internals may be optional. Brackish or sea water utilization will require the use of highly corrosion resistance materials and possibly coatings. Typically specified metals include alloy bronze, monnel, ni-resistant, or duplex stainless steels sometime combined with a corrosion resistant paint or specialized coating. 

TIRF experiments often involve specially coated substrates. A glass surface can be chemically derivatized to yield special physi- or... 

Chemically modified electrode (CME) An electrode covered with a special coating (of a conductor or semiconductor unless very thin), thereby altering its electrochemical properties. 

A number of different wools are special and sold under dilferent names such as cashmere wool. These wools have their own special characteristics that increase their cost and value. It is interesting that many animals have developed their own special coats to overcome their native environment. Thus, because cashmere goats live in a cold mountain temperature, their wool is an elfective material to protest against the cold. 

Lamella settlers are gravity settlers that use a large number of inclined flat plates, closely packed, so that the distance between the plates is small. The gravitational action makes the cells move in the direction of the lower surface of the individual separating space between two plates. Once settled, the particles slide down in a layer towards the plate periphery and then into the sludge hopper. For the same required sedimentation area, lamella settlers are much more compact than vertical ones. Theoretically, their total sedimentation area is the sum of the horizontally projected areas of all plates. In practice, however, only 50% of this total area is effective [137]. The main problem with inclined settlers is that the cells tend to adhere to the plates. Special coating of the plate surface and vibration of the whole lamella pack may alleviate this problem. 

Fillers and specially coated color printer paper... 

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