Laser welding of brass and stainless steel alloys is of special importance due to its wide application in the industries related to energy production. In this study, laser welding of heterogeneous metals was performed in a laboratory. Measurements of the temperature around the molten pool showed changes in the welding conditions. By changing different parameters such as welding speed, frequency, and pulse width, different thermal gradients were obtained. The results showed that the formation of the molten pool was asymmetric, and it was mostly done by melting the brass alloy. Due to the lower melting temperature and the high heat transfer rate of the brass alloy, the measured temperature and the molten volume of this alloy were higher. The microstructure of the molten pool also included intermetallic compounds. Increasing the dimensions of the molten pool (width and depth) by raising the peak power and reducing the welding speed was more effective than other parameters. The microhardness results also indicated the higher weld strength of the brass alloy with stainless steel rather than pure copper. At the range of the investigated process parameters, the adjacent temperature near the molten pool was about 20% (30 °C) higher for the brass alloy, in comparison to stainless steel, when the pulse frequency and pulse width were changed.
Although polymer-based nanocomposites have great application potential in many fields, compared with the application of ferroelectric nanocomposites in functional microscale structures and devices, especially in the field of photonics microdevices fabricated by laser processing, the development of polymer-based nanocomposites is relatively lagging behind. In this study, the polyvinylidene fluoride ferroelectric composite material was taken as the research object, and the preparation method of polymer nanocomposite material suitable for laser microstructure processing was solved by exploring the material functionalization method. The control of the optical properties of polyvinylidene fluoride ferroelectric composites was achieved through material design, control of the size of nanoparticles in the prepared polymer nanocomposites, and characterization of their structures and properties. Two-dimensional and three-dimensional structures of polymer nanocomposites were prepared by laser microstructure processing technology, and the optical properties of the microstructures were evaluated. When the applied stress field was zero, the macroscopic coercive field was larger, and the hystereswas loop was wider, while the butterfly curve changed rapidly near the coercive field, and the strain was negative. From the test results of the scanning electron microscope, it can be concluded that the lowest average power to find ablation traces was 0.06 mw, and the affected area was very small, and there was no damage to the surrounding nanotubes. Therefore, this paper believes that the damage threshold of carbon nanotubes was slightly less than 0.06 mw. This study contributes to the development of nanocomposite preparation methods for laser micromachining.
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