Characterization and modeling of laser transmission welded polyetherketoneketone (PEKK) joints: Influence of process parameters and annealing on weld properties

IF 3.8 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY
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Abstract

Welding high-performance thermoplastics has gained popularity across various industries such as automotive, aerospace, and medical. Laser transmission welding (LTW) has emerged as an effective method for joining thermoplastic parts due to its precise control and high joint quality. PAEK (polyaryletherketone) are wide spreading over various industrial applications as a substitute to metals and thermosets when high durability and performance are required. Polyetherketoneketone (PEKK) is one of these PAEK and it has received less attention than PEEK until now. PEKK, being a semi-crystalline thermoplastic, requires additional care during processing due to its propensity to crystallize. This study presents both experimental and numerical investigations into LTW of PEKK molded parts, aiming to understand the influence of welding parameters and crystallinity on weld joint morphology and mechanical properties. PEKK plates, prepared in amorphous and semi-crystalline states, are subjected to LTW using a 975 nm diode laser. Material characterization confirms differences in crystallinity between the samples, which affect their thermal and optical properties, which are crucial for welding. Welding tests are conducted with varying laser power (between 75 and 95 W) and semi-transparent part thickness (2 and 4 mm). The morphology of joints is analysed. Assemblies undergo post-weld annealing treatment to examine its influence on weld crystallinity and consequent mechanical properties. Results reveal an anisotropic distribution of crystallinity within the heat-affected zone (HAZ). The depths of the molten layer (ML) and semi-crystalline layer (scL) vary with laser power and assembly type. A notable decrease in weld strength with laser power is highlighted, while annealing leads to enhanced crystallinity and improved weld strength. Despite variations, high weld strengths are achieved with annealing. Computational modelling elucidates the complex interplay between laser irradiation, temperature distribution, and crystallization kinetics observed experimentally. Overall, this comprehensive investigation provides valuable insights into optimizing LTW parameters for PEKK parts.

激光透射焊接聚醚酮酮 (PEKK) 接头的表征和建模:工艺参数和退火对焊接性能的影响
焊接高性能热塑性塑料在汽车、航空航天和医疗等各行各业越来越受欢迎。激光传输焊接(LTW)因其精确的控制和较高的焊接质量,已成为连接热塑性塑料部件的有效方法。PAEK(聚芳基醚酮)作为金属和热固性塑料的替代品,在要求高耐用性和高性能的各种工业应用中得到了广泛的推广。聚醚醚酮(PEKK)是 PAEK 的一种,但到目前为止,它受到的关注还不如 PEEK 多。PEKK 是一种半结晶热塑性塑料,由于容易结晶,因此在加工过程中需要格外小心。本研究对 PEKK 模制件的 LTW 进行了实验和数值研究,旨在了解焊接参数和结晶度对焊点形态和机械性能的影响。在无定形和半结晶状态下制备的 PEKK 板材使用 975 nm 的二极管激光器进行 LTW。材料表征证实了样品之间结晶度的差异,这种差异会影响样品的热性能和光学性能,而这些性能对焊接至关重要。焊接测试在不同的激光功率(75 至 95 W)和半透明部件厚度(2 至 4 mm)下进行。对接头的形态进行了分析。组装件经过焊后退火处理,以检查其对焊接结晶度和由此产生的机械性能的影响。结果显示,热影响区(HAZ)内的结晶度呈各向异性分布。熔融层(ML)和半结晶层(scL)的深度随激光功率和装配类型而变化。随着激光功率的增加,焊接强度明显降低,而退火可提高结晶度并改善焊接强度。尽管存在差异,但通过退火可获得较高的焊接强度。计算建模阐明了实验观察到的激光辐照、温度分布和结晶动力学之间复杂的相互作用。总之,这项综合研究为优化 PEKK 零件的 LTW 参数提供了宝贵的见解。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
CiteScore
7.10
自引率
9.80%
发文量
58
审稿时长
44 days
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