Calorizing

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Calorizing

 

in Europe, aliting, the saturation of the surface of steel or other metal parts with aluminum for the purpose of increasing resistance against scaling at temperatures up to 1100°C and of increasing resistance to atmospheric corrosion. Most frequently parts of low carbon austenitic steels and refractory alloys are calorized. Calorizing is performed in powder mixtures (50 percent Al or fer-roaluminum, 49 percent Al2O3 and 1 percent NH4Cl or 99 percent ferroaluminum and 1 percent NH4Cl). At 1000°C with a soaking of eight hours, a layer of 0.4–0.5 mm saturated with aluminum is formed. Calorizing is also done by metallizing (a layer of aluminum powder is deposited on the surface of the parts, and after the deposition of an insulating coating the part is subjected to diffusion heat treatment), by painting the parts with aluminum paint (with subsequent heat treatment in a protective atmosphere), by an aluminum melt (with 6–8 percent iron) at 700–800°C followed by soaking, and by other methods. Calorizing is used in the production of valves for automotive engines, blades and nozzles of gas turbines, oil and gas cracking equipment parts, steam superheater pipes, furnace parts, and so on. Calorizing in molten aluminum is widely used instead of hot zinc plating (sheet, wire, pipes, construction parts).

REFERENCE

Gorodnov, P. T. Povyshenie zharostoikosti stal’nykh izdelii metodom alitirovaniia. Moscow, 1962.

A. N. MINKEVICH

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.