Powders

10 pages, 4153 KiB

Open AccessArticle

Influence of Process Parameters on Porosity and Hot Cracking of AISI H13 Fabricated by Laser Powder Bed Fusion

by Siyuan Qin, Yutao Bo, Simone Herzog, Bengt Hallstedt, Anke Kaletsch and Christoph Broeckmann

Powders 2022, 1(3), 184-193; https://doi.org/10.3390/powders1030012 - 09 Sep 2022

Cited by 9 | Viewed by 1918

Laser powder bed fusion is an attractive manufacturing technology promising novel components for the aircraft, automobile, and medical industries. However, depending on the material, some defects in the parts, especially pores or microcracks, cannot be avoided in the LPBF process. To achieve a part with low defect density, the optimal parameter sets must be determined. Many investigations have focused on how laser speed and laser power influence the melting process and the relative density of as-built parts. In this study, we considered laser and heated powder beds as two energy input sources, represented by volume energy density and preheating temperature, respectively. The interaction of these two energy inputs for the fabrication of AISI H13 was investigated. It was found that high preheating temperatures shifted the optimal parameter sets from the low energy density area to the high energy density area. In addition, high preheating also led to hot cracking, which was confirmed with Scheil solidification simulations. Full article

(This article belongs to the Special Issue Feature Papers in Powders)

► Show Figures

Figure 1

29 pages, 4316 KiB

Open AccessReview

Advances in Microfluidic Synthesis of Solid Catalysts

by Huihui Chen, Zhenhua Dong and Jun Yue

Powders 2022, 1(3), 155-183; https://doi.org/10.3390/powders1030011 - 04 Aug 2022

Cited by 2 | Viewed by 2494

Abstract

Heterogeneous catalysis plays a central role in the chemical and energy fields, owing to the high and tunable activities of solid catalysts that are essential to achieve the favorable reaction process efficiency, and their ease of recycle and reuse. Numerous research efforts have been focused on the synthesis of solid catalysts towards obtaining the desired structure, property and catalytic performance. The emergence and development of microfluidic reactor technology provide a new and attractive platform for the controllable synthesis of solid catalysts, primarily because of its superior mixing performance and high heat/mass transfer efficiency. In this review, the recent research progress on the synthesis of solid catalysts based on microfluidic reactor technology is summarized. The first section deals with the synthesis strategies for solid catalysts, including conventional methods in batch reactors and microfluidic alternatives (based on single- and two-phase flow processing). Then, different kinds of solid catalysts synthesized in microflow are discussed, especially with regard to the catalyst type, synthetic process, structure and property, and catalytic performance. Finally, challenges in the microreactor operation and scale-up, as well as future perspectives in terms of the synthesis of more types of catalysts, catalyst performance improvement, and the combination of catalyst synthesis process and catalytic reaction in microreactors, are provided. Full article

(This article belongs to the Special Issue Feature Papers in Powders)

► Show Figures

Graphical abstract

26 pages, 15999 KiB

Open AccessFeature PaperReview

Microstructural and Micromechanical Characterization of Feedstock for Cold Spray Additive Manufacturing and Processing

by Bryer C. Sousa, Kyle Tsaknopoulos and Danielle L. Cote

Powders 2022, 1(3), 129-154; https://doi.org/10.3390/powders1030010 - 29 Jul 2022

Cited by 1 | Viewed by 1682

Abstract

Due to the processes solid-state nature, cold gas-dynamic spray metal additive manufacturing may be considered microstructurally and micromechanically retentive, such that properties of the feedstock material are refined and partially retained, influencing component performance. As a result, cold spray processing enables unique freedoms regarding feedstock, which can be pre-processed using chemical, thermal, and mechanical treatments to produce powder properties that achieve finely controlled consolidations with application-specific behaviors. Given such features of the cold spray process, the present review article is concerned with the through-process integration of mechanically and microstructurally characterized feedstocks for optimizable cold spray metal additive manufacturing. Therefore, in this paper, we consider how nanoindentation (dynamic, static, and quasi-static) was coupled with microstructural characterization for experimental feedstock evaluation, testing, and characterization. Atomized aluminum alloys, atomized stainless steel, and copper feedstocks, among others, were considered. Accordingly, the review validates how microparticle feedstock pre-processing and characterization in cold spray metal additive manufacturing and processing lead to controllable component performance and properties. Full article

(This article belongs to the Special Issue Powders for Cold Spray Coatings)

► Show Figures

Figure 1

Journal Menu

Journal Browser

Powders, Volume 1, Issue 3 (September 2022) – 3 articles

Further Information

Guidelines

MDPI Initiatives

Follow MDPI