Enamel Coatings

The demand for pipe-coating enamels tends to fluctuate, depending on the success of oil and gas exploration. In the United Kingdom plastic-coated pipes are used on shore. Most production is exported for use in the Middle and Far Eastern regions. 

Residual Compressive Stress. Residual compressive stress ia commercial ground coat enamels varies with enamel thickness ... 

Thermal shock resistance is a direct function of enamel thickness. The greater the residual compressive stress in the porcelain enamel, the greater is the resistance to thermal shock failure. Thin coatings, such as one-coat enamels or the two-coat enamels having alow expansion titania covet coat, provide excellent thermal, shock resistance. 

Aluminum does not require a ground coat. Enamel is generally applied by spraying, with firing accomplished by heating to 450-550°C (850-1040°F) for 2-10 min. 

Epoxy c Ketone, ethers, esters, toluene, xylene Marine coatings, enamels, containers... 

Kelly-Moore Enviro-Coat Enamel No i5.io/gallon kellymoore.com 650-595-1654 Interior... 

Solvent, insecticides, synthesis of organic chemicals. Manufacture of protective coatings, enamels, rubber cements, dyes, motor fuels, pharmaceuticals, and vitamins. 

In the traditional enamelling methods, the adhesion is aided by the ground coat enamel and by adhesive oxides which arc responsible for galvanic corrosion of the metal and thus for coarsening the surface. More recent advances in technology allow direct application of the cover coat enamel onto the metal surface. This method is possible in the case of titania enamels and requires steel of special composition, either alloyed with titanium or carbon-free. Another possibility is based on the deposition of Ni on the metal surface. It is also necessary to adjust the slip composition and the coating thickness suitably the fired enamel thickness is only 0.1 —0.2 mm, compared with the usual 0.4 mm. 

The volume thermal expansion coefficient of iron is 360 — 400 x 10". That required for ground cover enamel is about 280 x 10 because its expansion increases by the dissolving of iron oxides. The expansion coefficient of the cover coat enamel frit should be in the range 325 — 345 x 10 ". ... 

The chemical composition of frit of an average ground coat and white cover coat enamel of the classical type is as follows (wt. %) ... 

In principle, enamels can be applied as a single layer or in multiple (two) layers The layers can be stoved separately or together. The classic processes operate with ground coat and cover coat enamels and one stoving per layer. 

Typical ground coat enamel compositions are given in Table 5.4-1. 

Table 5.4-1. Oxide Composition of a hard and soft Ground Coat Enamel for Steel- plate (in % by weight).

After stoving the ground coat enamel layer, the cover coat is applied and stoved. The purpose of the cover coat enamel layer is to endow the enameled object with its... 

Ground coat enamel contains cobalt and nickel oxide,s as adhesion-promoting oxides (good adhesion to the substrate)... 

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