Gray irons

Graphite is essentially an inert material and is cathodic to iron. This results in rapid attack of the iron in even mildly corrosive enviromnents. As the iron is removed, the reducing graphite flakes and corrosion products may form a barrier to further attack. This process is called graphitization because the 

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Gravure process Gray cast iron Gray iron... 

The life of a cage may be a few months and may produce 9000 Mg (10,000 tons) of quany rock. A gray-iron cage is used for alumina grinding, with metal particles removed magnetically. The advantage of... 

Gray iron has outstanding damping properties—that is, ability to absorb vibration—as well as wear resistance. However, gray iron is brittle, with poor resistance to impact and shock. Machinability is excellent. 

With some important exceptions, gray-iron castings generally have corrosion resistance similar to that of carbon steel. They do resist atmospheric corrosion as well as attack by natural or neutral waters and neutral soils. However, dilute acids and acid-salt solutions will attack this material. 

Gray iron is resistant to concentrated acids (nitric, sulfuric, phosphoric) as well as to some alkahne and caustic solutions. Caustic fusion pots are usually made from gray cast iron with low silicon content cast-iron valves, pumps, and piping are common in sulfuric acid plants. 

Generally, corrosion resistance is similar to gray iron. But duc tile iron can be used at higher temperatures—up to 590°C (I,I00°F) and sometimes even higher. 

Generally, nickel-alloy castings have superior toughness and impact resistance compared with gray irons. The nickel-alloy castings can be welded and machined. 

Venmri scrubbers have been applied to control PM emissions from utility, industrial, commercial, and institutional boilers fired with coal, oil, wood, and liquid waste. They have also been applied to control emission sources in the chemical, mineral products, wood, pulp and paper, rock products, and asphalt manufacrnring industries lead, aluminum, iron and steel, and gray iron production industries and to municipal solid waste incinerators. Typically, venturi scrubbers are applied where it is necessary to obtain high collection efficiencies for fine PM. Thus, they are applicable to controlling emission sources with high concentrations of submicron PM. 

Castings are designed to be loaded in compression because the compressive strength of gray iron is about three times that of its tensile strength. 

Table 3.2. Typical Data Showing llie Effect of Strengtii on Gray Iron Castings (11...

Gray iron to BS1452 A Tensile strengtii, N/mm-, of casting with section thickness of ... 

Cast Iron (e.g. BS1453) Oxyacetylene Gray irons but not malleable Matching color Not machinable... 

Nickel Copper (70/30) Metal arc I or all gray irons Easy to machine... 

Code of Practice for the Repair and Reclamation of Gray Iron Castings by Welding and Allied Methods, Proc. Inst. Brit. Foundrymen, 43 A1 14-122 (1950). 

Typical data showing the effect of strength on gray iron... 

Grau-gultigerz, n. tetrahedrite. -guss, m. gray cast iron, gray iron gray-iron casting, -kalk,... 

Iron/ carbon alloy, poured as a hot molten liquid into a mold. Usually produced as either gray iron (where flakes of graphite are embedded in an iron matrix) or nodular iron (spheroids of graphite in the matrix). 

Matsunaga, M. and I. Nakai (2000), Study of the origin of the silver luster on gray iron age pottery, Anatolian Archaeol. Stud. 9, 207-211. 

The suitability of gas absorption as a pollution control method is generally dependent on the following factors (1) availability of suitable solvent (2) required removal efficiency (3) pollutant concentration in the inlet vapor (4) capacity required for handling waste gas and (5) recovery value of the pollutant(s) or the disposal cost of the unrecoverable solvent. Impingement plate scrubbers are typically used in the food and agriculture industry, and at gray iron foundries. 

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