METHOD OF MANUFACTURING BRAZED ARTICLES PARTICULARLY HEAT EXCHANGERS,申请号GB19730023425-传众专利搜索

METHOD OF MANUFACTURING BRAZED ARTICLES PARTICULARLY HEAT EXCHANGERS

申请公布号：GB1432066(A)

申请号：GB19730023425

申请日期：1973.05.16

申请公布日期：1976.04.14

申请人：

DES USINES CHAUSSON SA

分类号：B23K1/19;B23K1/00;B23K1/20;B23K35/28;B23P15/26;C22F1/05;(IPC1-7):23K1/04;23K1/12

主分类号：B23K1/19

摘要：1432066 Brazing SOC ANON DES USINES CHAUSSON 16 May 1973 [23 May 1972] 23425/73 Heading B3R In a method of manufacturing a brazed article, e.g. a heat exchanger, the parts of the article are formed from aluminium alloy sheet containing magnesium and silicon and up to 0À05% copper, the parts are assembled and degreased, the assembly is heated to 580- 600‹ C., with a brazing alloy containing aluminium and 7-15% silicon in the presence of a metal or metal salt to promote removal of oxides on the parts to melt the brazing alloy and produce magnesium silicide in solution in the aluminium alloy of the parts, the assembly is cooled at a rate of at least 1‹ C. per sec. to about 300‹ C. to solidify the brazing alloy and maintain at least some of the magnesium silicide in solution, the assembly is heated to 180-250‹ C. to precipitate the magnesium silicide and then the assembly is cooled to ambient temperature. Sheets or strips of an aluminium alloy containing 0À1-0À5% silicon and 0À3-0À8% magnesium and possibly up to 0À3% iron, 0À5% zinc, 0À5% manganese and 0À05% copper, are heated to 250-290‹ C. for softening and header tank parts, louvres or straps are produced therefrom. The parts are assembled with an aluminium alloy containing 7-15% silicon and possibly 0À1-12% zinc, 0À005-3% boron or lithium, 0À01-10% magnesium and bismuth or antimony coated, hot or cold, on the parts, applied as a paste or by flame spraying with an anhydrous flux. If a simple aluminium silicon alloy is employed scraping, followed by dipping in acid or alkaline, rinsing in water and drying is necessary. These steps are unnecessary if the additives are present. The parts are temporarily joined by local welding or by jigs and are degreased in trichloroethylene and steam. The assembled parts may be brazed in an oven when they are dipped in or sprayed with aqueous flux containing metal salts and then heated in the oven to 580-600‹ C. at which temperature the brazing alloy melts and the magnesium and silicon of the parts form magnesium silicide. The parts are cooled by blowing air or gas thereon until the temperature reaches 300‹ C. when water is sprayed on the parts. The parts are then washed in an acid bath to remove residual flux and then in a water bath and then dried at 180-250‹ C. for 15 hours when the magnesium silicide is precipitated. Alternatively the parts are brazed in a salt bath by preheating to 540-560‹ C. in an oven and then dipping in a salt bath to melt the brazing alloy. The parts are then rapidly cooled as before. In a further alternative the brazing is effected in a vacuum or neutral atmosphere oven and in this case metallic magnesium is present adjacent the parts. The magnesium may be provided in the brazing alloy, by diffusion under vacuum or as a suspension in methylcellulose.