| 摘要 |
Purpose – This research aims to provide a theoretical method and data supports for a future study on interfacial reaction mechanism and spreading
mechanism between molten solder and V-shaped substrate, which also gives guidance for those complicated welding operation objects in brazing
technique.
Design/methodology/approach – Wetting experiments were performed to measure the contact angles at different temperatures of molten
Sn-3.0Ag-0.5Cu wetting on the quartz substrate with an included angle of 90°. According to the experimental results, the theoretical spreading
morphology of molten solder on V-shaped substrate at corresponding temperature was simulated by Surface Evolver.
Findings – The theoretical morphology profiles of the molten solder sitting on the V-shaped substrate are simulated using Surface Evolver when
the molten solder reaches spreading equilibrium. The spreading mechanisms as well as the impact of surface tension and gravity on interfacial energy
of the molten solder wetting on the V-shaped groove substrate are also discussed where theoretical results agree well with experiment results. The
contact area between the gas and liquid phases shows a tendency of first increasing and later decreasing. Otherwise, the spreading distance and
the height of the molten solder increases as the droplet volume increases as the included angle and the contact angle are given as constants, and
both the interfacial energy and the gravitational energy increase as well. This research has a wide influence on predicting the outcomes in commercial
impact and also gives guidance for those complicated welding operation objects in brazing technique.
Research limitations/implications – It is of very important significance in both science and practice to investigate the differences between the
flat surface and V-shaped surface. Some necessary parameters including intrinsic contact angle and surface tension need to be directly measured
when the droplet spreads on the flat surface. The relevant simulation conclusions on the inherent characteristics can be given based on these intrinsic
parameters. Compared with the flat surface, the V-shaped substrate is chosen for further discuss on the effects of gravity on the droplet spreading
behavior and the changes of apparent contact angle which can only occurs as the substrate is inclined. Therefore, this research provides theoretical
method and data supports for a future study on interfacial reaction mechanism and spreading mechanism between molten solder and substrate.
Practical implications – The research is developed for verifying the accuracy of the model built in Surface Evolver. Based on this verified model,
other researches on the spreading distance along y-axis and the contact area that are especially difficult to be experimentally measured can be
directly simulated by Surface Evolver, which can provides a convenient method to discuss the changes of horizontal spreading distance, droplet
height and contact area with increasing the included angle of V-shaped substrate or with increasing the droplet volume. Actually, the modeling
results are calculated for supplying the theoretical parameters and technical guidance in the welding process.
Social implications – This research provides theoretical method and data supports for a future study on interfacial reaction mechanism and
spreading mechanism between molten solder and substrate, which has a wide influence on prediction the outcomes in commercial impact and also
gives guidance for those complicated welding operation objects in brazing technique.
Originality/value – Surface Evolver, can also be used to discuss the structure and spreading mechanism of droplets on V-shaped substrates, which
have not been discussed before. |