Automobiles phosphate coating

In corrosion-resistant automobile bodies, the first—and probably the most important—layer of the paint system is the phosphate coating. Although it is the thinnest coating in the paint system [about 3 pm (0.1 mil) thick], it is the anchor for the subsequent layers [1]. 

Automobile bodies are generally fabricated from steel [9-11], therefore corrosion protection is one of the most important functions of automotive coatings. After the fabrication of the car body, the surface is coated (phosphate coating) by dipping into... 

Standards of Performance for Automobile and Tight Duty Truck Surface Coating Operations Standards of Performance for Phosphate Rock Plants Standards of Performance for Ammonium Sulfate Manufacture... 

The most common metal swarfs are iron-based [9,10] and produced by the machine tool and automobile industries. The resulting fine Fe particles oxidize in storage and form magnetite and hematite. Because they also contain flammable machine oils, this oxidation makes them pyrophoric and hence a liability. Because the particle surfaces are coated with oil, they cannot be incorporated in conventional cement. As demonstrated by Wagh and Jeong [3], the acid phosphate in the CBPC process acts like a detergent and exposes the surface of these particles to the acid-base reaction and binds them. 

The electrolytic deposition of a coating that is known as E-coat provides an excellent corrosion protection as evidenced by automotive coating. Today nearly all automobiles are corrosion protected by applying the cathodic E-coat, in which the steel body of a car is used as the cathode of the electrolytic deposition of a primer coat, on the surface of zinc phosphated steel. It is quite logical to consider that if an E-coat is applied to a chromate conversion-coated aluminum alloy surface, a significant improvement of the corrosion protection of aluminum alloys could be realized because such an attempt represents the combination of the two best components, i.e., chromate conversion coating and E-coat. We could find the best example that demonstrates the need of SAIE in such attempts. 

Organic phosphates are not chemically bonded to the polymer but can move in and out of the material. Evaporation of organic phosphates from car seats can result in a tacky coating on windows and other surfaces in the interior of the automobile, which can result in human exposure by skin contact and inhalation. 

The use of electrocoat or e-coat paints and primers is another technology that found extensive use in the 1980s. Electrocoated paint is applied on the part to be coated in a paint bath, and electrical current is applied. This method enables painting of the most intricate parts. The electrocoated automobiles were more corrosion resistant. The surface rust was approximately three times higher, and the number of perforations were also higher in vehicles that were treated in the standard conventional manner. Some of these differences may be because of zinc coating on the steel and phosphatizing. However, electroplated paint systems had a noticeable effect on corrosion resistance. 

One of the applications of CCTP polymers and macromonomers has been in the automotive industry. Typically, automobile steel panels require several paint layers to achieve hardwearing coatings. The first layer is commonly an inorganic mst proofing zinc or iron phosphate layer. Primer comprises... 

Fifiform Cemsien in Automobiles. The inqxx--tance of filiform corrosion of aluminum is increasing due to the increase use of aluminum for outer body sheet in automotive applications. An all-aluminum body shell made entirely of aluminum alloys is about 35% lighter than an all-steel body and meets the same stiffriess requirements (Ref 25). Sheet panels are first conversion coated (phosphated) and then painted with a three-coat paint system consisting of a cathodic electrocoat, a primer/surfacer coat, and a top coat Present experience indicates that the potential for fill-... 

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