Scott E. Julien, Nathaniel Hanson, Joseph Lynch, Samuel Boese, Kirstyn Roberts, Taşkin Padir, Ozan C. Ozdemir, Sinan Müftü
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引用次数: 0
Abstract
Cold spray is a material deposition technology with a high deposition rate and attractive material properties that has great interest for additive manufacturing (AM). Successfully cold spraying free-form parts that are close to their intended shape, however, requires knowing the fundamental shape of the sprayed track, so that a spray path can be planned that builds up a part from a progressively overlaid sequence of tracks. Several studies have measured track shape using ex situ or quasi-in situ approaches, but an in situ measurement approach has, to the authors’ knowledge, not yet been reported. Furthermore, most studies characterize the track cross section as a symmetric Gaussian probability density function (PDF) with fixed shape parameters. The present study implements a novel in situ track shape measurement technique using a custom-built nozzle-tracking laser profilometry system. The shape of the track is recorded throughout the duration of a spray, allowing a comprehensive investigation of how the track shape evolves as the deposit is built up. A skewed track shape is observed—likely due to the side-injection design of the applicator used—and a skewed Gaussian PDF—a more generalized version of the standard Gaussian PDF—is fit to the track profile. The skewed Gaussian fit parameters are studied across two principal nozzle path parameters: nozzle traverse speed and step size. Empirical relationships between the fit parameters and the nozzle path parameters are derived, and a physics-based inverse relationship between nozzle speed and powder mass deposition rate is obtained. One of the fit parameters is shown to be an effective means of monitoring deposition efficiency during spraying. Overall, the approach presents a promising means of measuring track shape, in situ, as well as modeling it using a more general shape function.
冷喷涂是一种材料沉积技术,具有沉积率高、材料性能优越等特点,对增材制造(AM)具有极大的吸引力。然而,要成功冷喷出接近预定形状的自由形状零件,需要了解喷涂轨迹的基本形状,这样才能规划喷涂路径,从逐渐叠加的轨迹序列中生成零件。有几项研究使用原位或准原位方法测量了轨迹形状,但据作者所知,还没有关于原位测量方法的报道。此外,大多数研究将轨道横截面描述为具有固定形状参数的对称高斯概率密度函数(PDF)。本研究使用定制的喷嘴跟踪激光轮廓测量系统,实施了一种新颖的原位轨道形状测量技术。在整个喷涂过程中记录轨迹的形状,以便全面研究轨迹形状是如何随着沉积物的形成而演变的。可以观察到倾斜的轨迹形状--可能是由于所使用的喷头采用了侧喷设计--并对轨迹轮廓拟合出倾斜高斯 PDF(标准高斯 PDF 的更广义版本)。在两个主要喷嘴路径参数(喷嘴横移速度和步长)之间对倾斜高斯拟合参数进行了研究。得出了拟合参数与喷嘴路径参数之间的经验关系,并得出了喷嘴速度与粉末质量沉积率之间基于物理学的反比关系。其中一个拟合参数被证明是监测喷涂过程中沉积效率的有效手段。总之,该方法提供了一种现场测量轨迹形状以及使用更通用的形状函数对其进行建模的可行方法。
期刊介绍:
From the scientific to the practical, stay on top of advances in this fast-growing coating technology with ASM International''s Journal of Thermal Spray Technology. Critically reviewed scientific papers and engineering articles combine the best of new research with the latest applications and problem solving.
A service of the ASM Thermal Spray Society (TSS), the Journal of Thermal Spray Technology covers all fundamental and practical aspects of thermal spray science, including processes, feedstock manufacture, and testing and characterization.
The journal contains worldwide coverage of the latest research, products, equipment and process developments, and includes technical note case studies from real-time applications and in-depth topical reviews.