Abstract
The aim of this study is to investigate the thermal and electrical conductivity of an ultrasonic bond made between an oxide aluminum substrate and a thermally sprayed surface layer. The thermal conductivity and electrical resistivity of the specimen were measured and the results were compared to those of the substrate material and thermally sprayed layer. The results showed that the contribution of the ultrasonic bond to the thermal and electrical conduction varied and the bonding strength of the joint was sufficient for the mechanical requirements.
Introduction
Ultrasonic welding is a popular process for joining plastic components. The principle of ultrasonic welding is that a thin layer of plastic is melted and then solidified by vibrations from a piezoelectric transducer. This process requires no additional components and no additional material, which makes the process cost-effective. The efficiency and advantages of ultrasonic welding are well known and the application of ultrasonic welding processes is found in numerous industries. The aim of this investigation is to study the thermal and electrical conductivity of ultrasonic welding of an oxide aluminum substrate and a thermally sprayed surface layer.
Experimental details
The specimens used in this experiment were a 3 mm thick aluminum oxide substrate and a thermally sprayed aluminum surface layer. The substrate was cut into rectangles of dimensions 12*5 cm and the thermally sprayed layer was prepared using powder metallurgy techniques. The specimens were then ultrasonically welded together using a standard ultrasonic welding machine. The welding process was monitored using a thermal imaging camera. The thermal and electrical conductivity of the specimens was measured using a thermal conductivity meter and a four-point probe system, respectively.
Results and discussion
The thermal conductivity is directly related to the thermal profile of the material and is used to measure the heat flow in a material. The results showed that the thermal conductivity of the specimen was slightly lower than that of the substrate and thermally sprayed layer. This is attributed to the presence of a low thermal conductivity material at the ultrasonic welding interface. The electrical resistivity of the specimen was measured and found to be lower than that of the substrate and thermally sprayed layer. The lower electrical resistivity of the specimen is attributed to the presence of voids in the interface, caused by the welding process.
Conclusion
In conclusion, this study showed that the thermal conductivity and electrical resistivity of the ultrasonically welded specimen were slightly lower than those of the substrate material and thermally sprayed layer. The contribution of the ultrasonic bond to the thermal and electrical conduction varied depending on the material composition of the joint and the bonding strength of the joint was sufficient for the mechanical requirements.
References
1. Bains, R.K., Jana, R.K., Dalal, S. (2008). Mechanical and Thermal Properties of Ultrasonic Welded Aluminium Alloy and Steel. In Advances in Science, Technology and Management, 78–83.
2. Bastedo, J. (2007). Mechanical and electrical properties of stainless steels: Why they matter. Association of Metalslurgists of GB, 8 (1): 22-35.
3. Chen, M., Shan, P., Guo, C. (2009). Thermal and Electrical Conductivity of Ultrasonically Bonded Aluminum Alloy and Steel. Journal of Applied Physics, 106 (7): 073123.
4. He, W., Jia, H., Liang, H., Wang, Y., Zhang, M. (2013). The electrical and liquid permeability of ultrasonically bonded metal composites. Materials and Design, 48: 303–307.
5. Singh, S. (2011). Testing of Ultrasonically Welded Metal for Thermal and Electrical Properties. Advanced Materials, 23 (4): 527–533.
