{"title":"Powder stream characteristics of replaceable alumina and brass nozzle tips for directed energy deposition","authors":"Hong Seok Kim, Sang Hu Park","doi":"10.1016/j.addma.2025.104734","DOIUrl":null,"url":null,"abstract":"<div><div>This study explores the performance of a replaceable alumina nozzle tip for directed energy deposition (DED), highlighting its advantages over traditional copper and brass nozzles, which are prone to high-temperature wear. Key innovations include a modular design for easy replacement of worn sections and the use of alumina, which provides superior resistance to mechanical, thermal, and chemical degradation, along with low laser absorption, making it ideal for prolonged high-temperature deposition. CFD simulations combined with a discrete phase model predict that alumina’s higher restitution coefficient (<em>e</em>) increases powder stream divergence and shifts the powder focus plane upward. High-speed camera observations confirmed that the alumina nozzle tip results in a wider powder spot size (∼26.1 %) and an elevated powder focus plane (∼19.3 %) compared to brass. Deposition experiments showed that the optimal substrate position for maximizing deposition height is well below the powder focus plane. To explain this, the study introduces powder incorporating efficiency (<em>η</em><sub><em>i</em></sub>), which, alongside powder focusing efficiency (<em>η</em><sub><em>f</em></sub>), significantly affects powder deposition efficiency (<em>η</em><sub><em>d</em></sub>), expressed as <em>η</em><sub><em>d</em></sub> = <em>η</em><sub><em>f</em></sub> × <em>η</em><sub><em>i</em></sub>. The alumina nozzle tip demonstrated a ∼5 % higher deposition height and ∼16 % lower nozzle tip temperatures compared to brass, making it suitable for high-powder-flow processes, such as high-deposition-rate DED and high-speed laser material deposition.</div></div>","PeriodicalId":7172,"journal":{"name":"Additive manufacturing","volume":"102 ","pages":"Article 104734"},"PeriodicalIF":10.3000,"publicationDate":"2025-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Additive manufacturing","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2214860425000983","RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ENGINEERING, MANUFACTURING","Score":null,"Total":0}
引用次数: 0
Abstract
This study explores the performance of a replaceable alumina nozzle tip for directed energy deposition (DED), highlighting its advantages over traditional copper and brass nozzles, which are prone to high-temperature wear. Key innovations include a modular design for easy replacement of worn sections and the use of alumina, which provides superior resistance to mechanical, thermal, and chemical degradation, along with low laser absorption, making it ideal for prolonged high-temperature deposition. CFD simulations combined with a discrete phase model predict that alumina’s higher restitution coefficient (e) increases powder stream divergence and shifts the powder focus plane upward. High-speed camera observations confirmed that the alumina nozzle tip results in a wider powder spot size (∼26.1 %) and an elevated powder focus plane (∼19.3 %) compared to brass. Deposition experiments showed that the optimal substrate position for maximizing deposition height is well below the powder focus plane. To explain this, the study introduces powder incorporating efficiency (ηi), which, alongside powder focusing efficiency (ηf), significantly affects powder deposition efficiency (ηd), expressed as ηd = ηf × ηi. The alumina nozzle tip demonstrated a ∼5 % higher deposition height and ∼16 % lower nozzle tip temperatures compared to brass, making it suitable for high-powder-flow processes, such as high-deposition-rate DED and high-speed laser material deposition.
期刊介绍:
Additive Manufacturing stands as a peer-reviewed journal dedicated to delivering high-quality research papers and reviews in the field of additive manufacturing, serving both academia and industry leaders. The journal's objective is to recognize the innovative essence of additive manufacturing and its diverse applications, providing a comprehensive overview of current developments and future prospects.
The transformative potential of additive manufacturing technologies in product design and manufacturing is poised to disrupt traditional approaches. In response to this paradigm shift, a distinctive and comprehensive publication outlet was essential. Additive Manufacturing fulfills this need, offering a platform for engineers, materials scientists, and practitioners across academia and various industries to document and share innovations in these evolving technologies.