SusChEM: Sustainable material use in laser deposition: integrating experimental design, environmental impact assessment and economic evaluation

用于制造金属部件的传统方法通常需要铸造或锻造制造工艺，如挤压或锻造。为了达到规定的表面光洁度、尺寸精度和几何复杂性，通常需要二次加工步骤。但加工既浪费材料，即从大块（加工芯片）中去除的废料，也浪费能源，从可持续发展的角度来看，传统方法效率极低。作为一种替代方案，人们正在探索直接金属沉积技术，这种技术通过熔化金属粉末并仅在需要的地方沉积材料来制造固体金属部件，从而通过添加而不是减少材料来制造部件。这种制造策略的改变旨在通过避免（或减少）所需二次加工的程度，从本质上减少能源需求和材料浪费。然而，实际的沉积效率，即实际成为固结成分一部分的原料的比例，已被证明低至~5%。在实践中，粉末的剩余部分一般不重复使用，而成为废物（废粉），就像加工芯片一样。因此，这些直接金属沉积工艺在可持续性方面也提出了关键问题。本研究计划有三个主要研究目标：制定金属直接沉积技术环境影响评价和经济评价的定量评估框架，利用该框架指导利用废粉末和加工芯片作为金属直接沉积替代原料的实验设计空间，并实施实验设计，包括精心控制的组件制造，以及深入的表征和测试。本研究将各种评估和评估工具纳入定量评估框架，以捕获与直接金属沉积相关的实验变量，特别是在使用替代原料时。该框架的制定将与实验设计空间相结合，从而指导实验设计空间，而不是像目前评估研究的规范那样，在所有实验参数都已严格定义之后进行。总体而言，该研究将促进对直接金属沉积的性能-可持续性-经济权衡空间的理解。直接金属沉积是一项相对较新的技术，由于它能够通过增加而不是减少材料来制造零件，因此被推广为具有成本效益和可持续性。然而，该工艺目前在材料利用方面有局限性，但似乎足够强大，可以通过利用替代原料来克服这些局限性。从广泛的角度来看，这些主题提供了一个基本的机会，以突出性能，可持续性和经济性之间的权衡，进一步促进可持续性和经济评估在设计过程的早期结合。

1605392 Schoebubg, Julie M.Conventional methods used to fabricate metallic components generally require casting or wrought fabrication processes such as extrusion or forging. Secondary machining steps are generally necessary in order to achieve specified surface finish, dimensional accuracy and geometrical complexity. But machining wastes both material, i.e., the scrap material removed from the bulk part (machining chips), and energy, rendering conventional methods highly inefficient from a sustainability perspective. As an alternative, direct metal deposition techniques are being explored, which create solid metal parts by melting metal powder and depositing material only where it is wanted, thus fabricating the component by adding, rather than subtracting material. This change in fabrication strategy is intended to inherently reduce both energy requirements and material waste by avoiding (or reducing) the extent of secondary machining required. However, the actual deposition efficiency, i.e., fraction of feedstock material that actually becomes part of the consolidated component, has been demonstrated to be as low as ~5%. In practice, the remainder of the powder is generally not reused, and becomes waste (waste powder), just like the machining chips. Consequently, these direct metal deposition processes also present critical issues in terms of sustainability. This research program has three primary research objectives: to formulate a quantitative assessment framework for environmental impact assessment and economic evaluation of direct metal deposition technologies, to utilize this framework to guide the experimental design space for utilizing waste powder and machining chips as alternative feedstock materials in direct metal deposition, and to implement the experimental design, including carefully controlled component fabrication, coupled with in-depth characterization and testing. This research incorporates various assessment and evaluation tools into a quantitative assessment framework that captures the experimental variables associated with direct metal deposition, especially when utilizing alternative feedstock materials. This framework will be formulated so that it is integrated with and therefore guides the experimental design space, rather than being carried out after all the experimental parameters have been rigidly defined, as is the current norm for assessment studies. Overall, the research will advance the understanding of the performance-sustainability-economics trade-off space for direct metal deposition. Direct metal deposition is a relatively new technology that is promoted to be cost effective and sustainable, due to its ability to create parts through addition, rather than subtraction, of material. Yet the process currently has limitations in materials utilization, but moreover appears to be sufficiently robust to potentially overcome these limitations through the utilization of alternative feedstock materials. From a broad perspective, these topics present a foundational opportunity to highlight trade-offs between performance, sustainability and economics, and furthermore to promote the incorporation of sustainability and economic assessment early in the design process.