不锈钢低真空加热过程去膜机理分析

Analysis on mechanism of removing oxide film on stainless steel by heating in low vacuum

关键词:  不锈钢低真空钎焊  去膜机理  碳还原作用  氧化膜  溶解

Key words:  brazing of stainless steel in low vacuum condition  mechanism of removing oxide film  carbon reductive  oxide film  solution

摘要:

在低真空条件下对供应态及800℃空气中氧化过的0Cr18Ni9不锈钢进行加热,同时对供应态不锈钢板进行熔融铜中浸泡试验.结果表明,低真空加热使不锈钢表面氧化膜结构发生变化,而这种氧化膜不能阻止熔融铜对不锈钢板的大量溶解.通过对真空钎焊不锈钢去膜机理的探讨以及热力学计算,提出低真空条件下碳能够起到还原松动氧化膜的作用;当熔融铜沿着开裂的氧化膜流动接触到不锈钢基体,在Ni原子向液态铜中优先扩散的带动下,不锈钢快速溶解并将氧化膜抬起,在表面张力作用下最终实现低真空钎焊氧化膜的彻底破除.

Abstract:

In low vacuum condition,0Cr18Ni9 stainless steel sheets,with one in supply state and the other pre-oxidized at 800℃ in air,were heated,and the steel sheet in supply state was soaked in molten copper. It was found that the structure of oxide film changed after heating in low vacuum environment,and this film can not prevent the solution of stainless steel by the molten copper. Through investigation into the mechanism of removing oxide film on stainless steel sheet in vacuum condition and thermodynamic calculations,it was proposed that carbon could deoxygenate and weaken the oxide film. Once the molten copper met the stainless steel substrate by flowing through the cracked oxide film,the stainless steel would rapidly dissolve due to the diffusion of Ni atoms into the molten copper,and subsequently the oxide film would float on the molten copper. Finally,the oxide film would be removed under the action of surface tension in low vacuum condition.