Enamel frit

Another large appHcation is as an ingredient in the production of charcoal briquettes. The amount of sodium nitrate used in charcoal briquette manufacture depends on the type and amount of wood and coal used. Typically charcoal briquettes contain up to almost 3% sodium nitrate. Sodium nitrate is also used in the manufacture of enamels and porcelain as an oxidizing and fluxing agent. In porcelain—enamel frits used for metal coating, the amount of sodium nitrate in a batch varies with the various metal bases to be coated, typically from about 3.8 to 7.8 wt %. 

Structural, Al alloy Oxidation catalyst Fluxes, enamel frit Glass, ceramics Detergents Fire retardants Rubber catalyst Photographic Antiknock agents Medicinals Fertilizers... 

For conventional wet processing of sheet steel, the porcelain enamel frit is ball-milled using clay, certain electrolytes, and water to form a stable suspension. This clay-supported slurry of small particles is called the sHp and has the consistency of a heavy cream. The ingredients of the mill batch are carefully controlled. The amount and purity of all materials in the mill, including the clay and water, affect the rheological character of the sHp as well as a number of the properties of the fined enamel such as chemical resistance, reflectance, gloss, color, and abrasion resistance. 

Shipment. The shipment of porcelain enamel is typically in 45-kg (100-lb) three-ply paper bags. More recently, 227-kg (500-lb) multi-ply cardboard barrels and bulk bags made of high strength woven polymers have been used. Porcelain enamel frit, powder, and premixed and premilled mill additions ate shipped in these flexible containers. 

Feldspar Silica sand Enamel frit Grog... 

Table 16.1 Typical enamel frit compositions (%) and a mill addition...

Acid resistance This property is best appreciated when the glass structure is understood. Most enamel frits are complex alkali metal borosilicates and can be visualised as a network of Si04 tetrahedra and BO, triangular configurations containing alkali metals such as lithium, sodium and potassium or alkaline earth metals, especially calcium and barium, in the network interstices. 

Anhydrous borax is used in the manufacture of glasses, glass wool, and metallurgical fluxes. Other uses are in enamels, frits, and glazes. It also is applied in fertilizers. 

The composition of enamelling frits is traditionally very variable and only recently there have been tendencies aimed at restricting the number of compositions to certain standard types. 

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 ". ... 

Titania enamel frits usually contain 38 —45 wt. % Si02, 12—17%B203, 16 — 21%Ti02, 10—15% alkali oxides, smaller amounts of MgO, AI2O3, P2O5 and... 

Frit treatment before enamelling. Enamel frit is ground in ball mills to powder of particle size below 0.1 mm, either in water or dry, depending on whether it is to be applied in the form of slip (more frequently) or of dry powder. 

The most important industrially utilized silicon compounds include chlorosilanes, methylchlorosilanes, silicones, silicon dioxide and silicic acids in different forms, silicates in the form of glass, water glass, enamel frits, silicate fillers, zeolites, silicon carbide and silicon nitride. 

Sheet steel preparation Manufacture of enamel frit... 

The manufacture of enamel frits and the actual enameling are dealt with in greater detail in Sections 5.4.4 and 5.4.5 respectively. 

Raw materials for enamel frit manufacture Oxides, carbonates, nitrates and fluorides of ... 

For wet coating, enamel frits are converted into aqueous suspensions (slips) by grinding together with ... 

Dry premilled enamel frits and mill admi, tures can be introduced in water into the slip... 

Use Vitreous enamel frits, synthetic mica, metallurgy of aluminum and magnesium, ceramics, insecticide, opalescent glass. 

Use Fluoridation, laundry sours, opalescent glass, vitreous enamel frits, metallurgy (aluminum and beryllium), insecticides and rodenticides, chemical intermediate, glue, leather and wood preservative, moth repellent, manufacture of pure silicon. 

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