Abstract: In a method for brazing a sheet material without use of flux, an inert gas is firstly introduced into an oxygen pump to reduce an oxygen partial pressure in the inert gas to 1×10?10 Pa or less, and the sheet material is heated in a brazing furnace in an atmosphere of the inert gas discharged from the oxygen pump. A core alloy of the sheet material or a brazing filler alloy cladded to a surface of the core alloy contains Mg. Both the core alloy and the brazing filler alloy may contain Mg. Accordingly, brazability of the sheet material is sufficiently improved.

Abstract: In a method for brazing a sheet material without use of flux, an inert gas is firstly introduced into an oxygen pump to reduce an oxygen partial pressure in the inert gas to 1×10?10 Pa or less, and the sheet material is heated in a brazing furnace in an atmosphere of the inert gas discharged from the oxygen pump. A core alloy of the sheet material or a brazing filler alloy cladded to a surface of the core alloy contains Mg. Both the core alloy and the brazing filler alloy may contain Mg. Accordingly, brazability of the sheet material is sufficiently improved.

Abstract: The oxygen partial pressure control unit includes a gas purification section for purifying the gas having the oxygen partial pressure controlled within a range of from 0.2 to 10?30 atm, and a tank for storing the purified gas produced by the gas purification section. The purified gas stored within the tank is supplied to the another unit. The oxygen partial pressure control unit includes a circulation circuit including the tank and the gas purification section. The gas filled in the tank 20 is caused to circulate along the circulation circuit, and the purified gas produced by the gas purification section is stored in the tank.

Abstract: Work W to which oil has adhered is heated in the heating furnace 28 and adhering oil is evaporated. Gas containing the evaporated oil component is burned in the combustor 35. A portion of the generated combustion gas is circulated into the heating furnace 28 through the circulating duct 38, and an amount of the circulating combustion gas is controlled in accordance with a temperature in the heating furnace 28. Processing of aluminum materials is carried out using a base oil of hydrocarbon, the maximum molecular weight M of which is not less than 282 and not more than 378, and an additive of not less than 3% by weight of alcohol or carboxylic acid, the maximum molecular weight M of which is not more than 378.