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Auger electron spectroscopy applied to braze wettability

Conference ·
OSTI ID:6504882

The initial requirement for brazing is for the liquid metal filler alloy to wet the solid metal surfaces. While atomically clean metal surfaces are not necessary for good wettability, excessive oxygen (metal oxide) and/or carbon contaminants will leave non-wettable surfaces. The causes of non-wettable surfaces during brazing have been examined utilizing Auger electron spectroscopy. This surface spectroscopy with a sampling depth of 10 to 20A combined with sputter etching to provide film profiles was used to examine non-wettable specimens. Three different systems were studied. In the first case, carbon was found to segregate from the bulk to the surface of a nickel-copper alloy (Monel) during the braze heating. The formation of a graphitic layer was responsible for the non-wettability. In the second case, an external carbon contaminant was found on the surface of 316 stainless steel and resulted in a non-wettable surface. In the third situation, the non-wettability of 304 stainless steel was caused by a thick oxide film which formed in vacuum during brazing.

Research Organization:
Rockwell International Corp., Golden, CO (USA). Rocky Flats Plant
DOE Contract Number:
AC04-76DP03533
OSTI ID:
6504882
Report Number(s):
RFP-3202; CONF-810537-1
Country of Publication:
United States
Language:
English