| 摘要 |
1,222,764. Brazing. OLIN CORP. 5 June, 1969 [5 July, 1968], No. 28462/69. Heading B3R. A brazing slurry comprises a brazing metal or metal alloy powder having a melting point above 1000‹ F. and a particle size of 80 mesh or smaller in admixture with a hydroxy-containing polyoxyalkylene organic compound in an amount from 3 to 10% of the weight of the brazing powder and having a boiling point between 500‹ and 1000‹F. and a molecular weight of at least 200. The slurry may be used to braze sheet, plate, strip, angle tube or bar or powder or shot, the brazing alloy may be copper- 5 to 15% phosphorus, copper base alloy containing tin and manganese, pure copper and nickel base alloy, and the organic compound may be polypropylene diols, polypropylene thiols, nonyl phenol-oxyethylene adducts or polyethoxylated higher alcohols. A brazing flux and a volatile solvent, e.g. acetone or methyl ethyl ketone may be added to the slurry. In one example different shot materials viz. commercial purity copper and stainless steel containing 19% chromium, 10% nickel were brazed using copper-8% phosphorus alloy and nickel base alloy containing 0À36% carbon; 4À5% silicon; 0À2% iron; 2À9% boron balance nickel respectively. The shot was charged into a tumbler with polypropylene diol (molecular weight 1000) and the mixture was blended to wet the shot with the polypropylene diol. The brazing alloy powder was then added gradually and the mass was placed in a fixture and heated in a furnace in excess of 1000‹ F. to melt the brazing alloy and volatilize the polypropylene diol and produce a bonded porous mass permitting gas flow therethrough. In another example the brazing alloy powders as in the previous example were mixed with the same polypropylene diol to provide pastes to which acetone solvent was added just prior to use. This involved applying the slurry to, e.g. copper tubes in a copper header and heating the assembly to over 1000‹F. in a furnace to effect brazing. |
