电镀锡银钎料的均匀腐蚀性和抗氧化性分析

Analysis on corrosion behavior and oxidation resistance of Sn-electroplated silver brazing filler metals

为了评价电镀锡银钎料的腐蚀行为和抗氧化性,采用3.5%Na Cl水溶液评价其均匀腐蚀性,利用失重法、扫描电镜(SEM)及能谱分析仪(EDS)对钎料的腐蚀速率、腐蚀形貌及腐蚀物相进行观察分析.结果表明,Sn元素含量为2.4%时,电镀锡银钎料是全面腐蚀兼不均匀的局部点腐蚀,主要是富铜相、Cu Zn相及少量银相被腐蚀;当Sn元素含量为4.8%时,钎料为均匀面腐蚀,主要是银相、Ag Sn相、富铜相被腐蚀;当Sn元素含量升高至6.0%时,钎料为面腐蚀,主要是Ag Sn相、Cu Sn相、银相被腐蚀.镀锡前BAg50Cu Zn基体钎料主要是点腐蚀,镀锡后钎料主要是均匀腐蚀,随着Sn元素含量升高其耐蚀性降低.经60℃的3.5%Na Cl水溶液腐蚀80 h后,电镀锡银钎料的腐蚀速率介于0.6~0.75 mm/y之间,其耐腐蚀等级为2级.随着Sn元素含量升高,电镀锡银钎料的抗氧化性下降,但不影响其使用性能.

To reveal the corrosion behavior and oxidation resistance of Ag Cu Zn Sn brazing alloys with electroplating tin,3. 5% Na Cl solution was used to evaluate the uniform corrosion characteristic of brazing alloys. The weight loss method,scanning electron microscope(SEM) and energy dispersive spectrometer(EDS) were applied to analyze the corrosion rate,corrosion morphology and corrosion phases. 2. 4% Sn of brazing alloys presented general corrosion and uneven local pitting corrosion.Mainly Cu rich phase,Cu Zn compound phase and a small amount of Ag phase were corroded. When Sn content of silver brazing filler metals with electroplating tin was 4. 8%,it was uniform face corrosion. Mainly Ag phase,Ag Sn phase,Cu-rich phase corroded. When Sn content increase to 6. 0%,silver brazing filler metals with electroplating tin also occured face corrosion,then Ag Sn,Cu Sn,Ag phase was uniform corroded. SEM and EDS analysis showed that the pitting corrosion presented in the ABg50 Cu Zn substrate brazing alloys without electroplating tin. The uniform corrosion characteristic was found on the brazing filler metal with electroplating tin. With the increase of Sn content,the uniform corrosion resistance decreased. The corrosion rate of brazing alloys was 0. 6 ~ 0. 75 mm/y when it was dipped in the solution of 3. 5% Na Cl at 60 ℃ for 80 h,and its anti corrosion level was II grade. With the increase of Sn content,the oxidation resistance of brazing alloys with electroplatingt in decreased.