Dank seiner Vorteile hat sich das Laserschweißen von Kunststoffen zu einem etablierten Fügeverfahren entwickelt und es ersetzt mehr und mehr die bisher üblichen Fügeverfahren. Neue Entwicklungen beim Laserdurchstrahlschweißen ermöglichen nun das Überschreiten bisheriger Grenzen und eröffnen diesem Schweißverfahren weitere Anwendungsfelder.
Laser beam micro joining is known as one of the most promising applications of laser technology. The paper will give an overview of new applications in microtechnology using laser beams with high beam quality such as fiber lasers. Hence two new processes will be reported. The combination of small focus dimensions with high feed rates for scanning has advantages for metal welding as well as for polymer welding. Advanced Microsystems with complicated welding contours especially from the medical and biotechnological applications are challenging the limits of laser welding of polymers.
Plastics play an important role in almost every facet of our lives and constitute a wide variety of products, from everyday products such as food and beverage packaging, over furniture and building materials to high tech products in the automotive, electronics, aerospace, white goods, medical and other sectors [1]. The objective of PolyBright, the European Research project on laser polymer welding, is to provide high speed and flexible laser manufacturing technology and expand the limits of current plastic part assembly. New laser polymer joining processes for optimized thermal management in combination with adapted wavelengths will provide higher quality, high processing speed up to 1 m/s and robust manufacturing processes at lower costs. Key innovations of the PolyBright project are fibre lasers with high powers up to 500 W, high speed scanning and flexible beam manipulation systems for simultaneous welding and high-resolution welding, such as dynamic masks and multi kHz scanning heads. With this initial step, PolyBright will break new paths in processing of advanced plastic products overcoming the quality and speed limitations of conventional plastic part assembly. Completely new concepts for high speed processing, flexibility and quality need to be established in combination with high brilliance lasers and related equipment. PolyBright will thus open new markets for laser systems with a short term potential of over several 100 laser installations per year and a future much larger market share in the still growing plastic market. PolyBright will hence establish a comprehensive and sustainable development activity on new high brilliance lasers that will strengthen the laser system industry
The water-confinement of nanosecond-pulsed laser generated plasma provides great potential for preparation of ambient-stable silicon nanocrystals (Si-ncs) with quantum confinement size effect. Here, we report on blue-luminescent Si-ncs prepared by nanosecond KrF excimer laser ablation of doped-crystalline silicon target immersed in water. The Photoluminescence (PL) at low temperature show typical red-shift of the maxima assigned to the quantum confinement effect in Si-ncs. An introduction of ambient stable and less luminescent p-type doped Si-ncs into conjugated (poly(3-hexylthiophene) (P3HT) polymer leads to an interaction between electronic states of the nanocrystal and the polymer. An exciton transfer from the polymer into the nanocrysatal is observed. At the same time Si-ncs blended with P3HT polymer form a bulk-heterojunction. Dissociation of the exciton and the photoconductivity generation under 1.5AM irradiation is evidenced. The ratio value of ~1.7 between photo-and dark-conductivity is achieved at ~55 wt. % concentration of Si-ncs in P3HT polymer.
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