用显微结构法以及观察钎焊接头形成条件的方法,研究了钎焊时铝氧化膜在钎剂作用下脱除的机理.实验表明,钎剂中的F-是破坏氧化膜的主要成分,它使氧化膜起皱、破损形成窗口.钎剂中重金属离子本身没有破膜能力,在有F-存在时,则从窗口破损处渗入膜下,并在基底铝上沉积出重金属.铝氧化膜与基底铝分离的动力是界面上铝价态的被抬高,从而破坏了二者的结合.实验证明,完全不含氧化剂的钎剂不能去膜.
A study was made on the mechanism of oxide film removal in Al brazing byobserving the microsctructures and scanning the conditions of fillet formation.Ex-periments show that the F-ion can only break the film to form openning windowswhich act as entrance for the permeation of flux.The heavy metal ions them-selves are incapable of breaking film,but act as surfactant gradually permeate intothe film beneath at the site of grain boundaries,and are finally precipitated there.The effective removal occurs only when both F~- and surfactant are present.Thefinal removal of the film results from the spreading of molten filler.The causeof detaching film from the substrate metal is the increase of valence of Al effectedby certain oxidant contained in flux and thus disintegrates the combination betweenthem.It is concluded that the flux sheer free from oxidant can not remove thefilm.
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