焊丝药芯成分中FeSi45和FeS的添加量对焊缝金属润湿铺展性的影响

焊缝金属的润湿铺展性对装甲装备备件的焊接快速成形精度具有重要影响。采用焊缝熔宽、余高和润湿角表征焊缝金属的润湿铺展性,通过单道焊试验研究了焊丝药芯成分中FeSi45和FeS的添加量对焊缝金属润湿铺展性的影响规律,采用高速摄像研究了焊丝的熔滴过渡形式。结果表明:药芯成分中FeSi45和FeS的添加量分别为11.21%、0.2%时,可以获得润湿铺展性较好的焊缝;在小电流焊接条件下,药芯中添加FeSi45和FeS不会致使熔滴过渡形式发生改变,仍为大滴过渡,并且熔滴过渡稳定,无明显飞溅;在大滴过渡情况下熔滴的热焓较大,是焊缝金属润湿铺展良好的重要原因。

Ag,Cu对Sn-40Bi钎料合金钎焊性能和显微组织的影响

利用DSC,显微硬度仪以及SEM研究了合金元素Ag,Cu对Sn-40Bi钎料合金熔化特性、润湿铺展性、显微硬度以及焊点显微组织的影响。试验结果表明,在试验参数内随着Ag,Cu含量的增加,钎料的熔程减少,润湿铺展面积和维氏硬度增加,焊点中的Bi相得以细化。

CuSnTi钎料焊膏与焊片钎焊性能对比

为验证CuSnTi_(8-5)焊膏的熔化条件可以使用与焊片相同的焊接工艺,以及其钎焊接头性能不低于焊片接头性能,分别使用差热分析(DSC)、铺展性试验及测试接头力学性能,并使用扫描电子显微镜(SEM)与能谱仪(EDS)对接头进行组织分析,研究比较了焊膏与焊片相关性能表现。试验结果表明,CuSnTi_(8-5)焊膏与焊片有着接近的固液相温度,其完全满足焊片的焊接工艺;焊膏的润湿铺展性能优于焊片,且其钎焊接头强度高于焊片接头。分析其原因,在于同样的钎焊温度下,焊膏与基材作用时间长,可获得更多的润湿动能,因此呈现更高的铺展系数。另外,焊片无法像焊膏在焊缝周围形成明显的润湿圆角,影响了接头力学性能。通过组织分析,二者钎缝与母材间形成的Cu-Ti固溶体状态不同是造成了润湿性与接头力学性能差异的原因。

Liquid spreading behavior and surface wettability of copper ore under controlled sulfuric acid solution and surfactants

To reveal the potential effect of surfactant on improving surface wettability of copper ore,the droplet spreading behavior of sulfuric acid solution contained surfactant was visualized using high-speed camera and an image processing method,and the solid-liquid interaction was discussed in this study.The results show that liquid surface tension and ore surface roughness are the main factors affecting surface wettability.The effect of sulfuric acid solution concentration and surfactants on the surface wettability of ore is revealed via quantitative spreading area,spreading coefficient,and contact angle.The results of droplet spreading experiment show that the higher concentration of surfactant and sulfuric acid solution result in improving the wettability of ore,spreading coefficient,and decreasing contact angle.The“leaching reaction coefficient”and“surface activity coefficient”are introduced to modify the mathematical expression of the equilibrium contact angle.