基于圆锥过渡型变幅杆的颗粒增强钎料超声辅助半固态涂覆钎焊行为研究

发布时间：2018-01-31 02:47

  本文关键词： 变幅杆 超声辅助半固态涂覆钎焊 钎缝组织 力学性能 界面行为　出处：《太原理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：在低温条件下超声钎焊接头强度较低,性能较差,无法满足工业生产需求的问题。因此,为了低温钎焊更好的发展,无论是工艺优良且接头性能好的超声钎焊方法,还是新型的铝合金钎料都是亟待解决的问题。本研究从超声钎焊装置中变幅杆的设计出发,力求设计出的钎焊装置能够有利于促进润湿。继而研究超声参数对于钎料铺展的影响,以期得到超声辅助半固态涂覆钎焊试验的最优工艺参数。最后,使用Sn-9Zn-x Al_2O_3钎料超声辅助半固态涂覆钎焊6061铝合金,研究其接头组织及力学性能。进一步研究了不同尺寸颗粒对钎焊接头组织和性能的影响。主要的研究内容和结果如下:首先,振幅大的变幅杆有利于钎料的铺展。采用ANSYS有限元分析法进行变幅杆设计,最终得到变幅杆的尺寸:大端直径为40mm,小端直径为10.4mm,总长度为142.6mm,振幅比达到7.2。应力集中系数比阶梯型变幅杆的应力集中系数小且易加工的圆锥过渡型变幅杆。其次,采用自行装配的超声钎焊装置进行超声涂覆试验,确定超声辅助半固态涂覆钎焊的最优工艺参数。超声变幅杆与钎料相隔30mm左右,对钎料的铺展十分有利。当超声作用时间和超声功率增加时,钎料的铺展面积均有所变大,但不是无限变大。超声作用时间超过4s,面积不再增加,润湿角不再变化,处于一种稳定状态。当超声功率的数值超过350W时,面积的增加幅度减小,而厚度的减小幅度依旧维持,从而证明雾化作用对钎料有不良的影响。最终确定的超声辅助半固态涂覆钎焊工艺参数:超声时间5s(保证其充分铺展),超声功率350W,温度210℃,频率24k Hz,压力为3N。最后,采用Sn-9Zn,Sn-9Zn-1nm Al_2O_3和Sn-9Zn-1nm1μm Al_2O_3钎料超声辅助半固态涂覆钎焊6061铝合金。因纳米尺寸和双尺寸Al_2O_3颗粒的加入,提高了钎焊接头的强度。此外,钎料中加入不同尺寸的Al_2O_3颗粒,可以不同程度地细化钎缝中的富Zn相和Sn-Zn共晶组织,提高了Al和Zn的扩散深度,但是对界面处的冶金产物影响不大。进而分析Sn-9Zn,Sn-9Zn-1nm Al_2O_3和Sn-9Zn-1nm1μm Al_2O_3钎料超声辅助半固态涂覆钎焊6061铝合金接头断口,Sn-9Zn接头的断口是脆性断裂,而加入Al_2O_3颗粒钎料的接头断口都是韧性断裂,特别是Sn-9Zn-1nm1μm Al_2O_3钎料的断口,出现明显的韧窝。并在钎缝中央发生断裂并扩展。且其断口组织主要是基体β-Sn相、白色细长状的Sn-Zn共晶组织以及少量的富Zn相。通过上述的结果和分析可知,超声辅助半固态涂覆钎焊的性能优良,其接头强度最少为88MPa。
[Abstract]:At low temperature, ultrasonic brazing joints have low strength and poor performance, which can not meet the demand of industrial production. Therefore, the development of low-temperature brazing is better. Both the ultrasonic brazing method with excellent technology and good joint properties and the new aluminum alloy solder are the problems to be solved urgently. This study starts from the design of the variable amplitude rod in the ultrasonic brazing device. The designed brazing device can help to promote wetting. Then the influence of ultrasonic parameters on solder spreading is studied in order to obtain the optimal technological parameters of ultrasonic assisted semi-solid coating brazing test. Finally. 6061 aluminum alloy was brazed by Sn-9Zn-x Al_2O_3 solder assisted by semi-solid coating. The microstructure and mechanical properties of brazed joints were studied. The effects of different sizes of particles on the microstructure and properties of brazed joints were further studied. The main contents and results were as follows: first of all. The ANSYS finite element analysis method is used to design the variable amplitude rod. The size of the horn is 40 mm at the big end and 10.4 mm at the small end. The total length is 142.6mm, the amplitude ratio is 7.2. The stress concentration coefficient is smaller than that of the step horn. The ultrasonic coating test was carried out by using self-assembled ultrasonic brazing device to determine the optimum technological parameters of ultrasonic assisted semi-solid coating brazing. The distance between ultrasonic horn and solder was about 30mm. When the ultrasonic action time and ultrasonic power increase, the spread area of the filler metal becomes larger, but not infinitely larger. The ultrasonic action time is more than 4 s, the area will no longer increase. The wetting angle is no longer changed and is in a stable state. When the ultrasonic power exceeds 350 W, the increase of the area decreases, while the decrease of the thickness is maintained. It is proved that the atomization has a bad effect on the solder. The final parameters of ultrasonic assisted semi-solid coating brazing are: ultrasonic time 5s (ensure its full spread, ultrasonic power 350W). The temperature is 210 鈩，

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