2023 Annual International Solid Freeform Fabrication Symposium (SFF Symp 2023): Materials: Metals-Novel AM Methods II
Program Organizers: Joseph Beaman, University of Texas at Austin
Wednesday 1:10 PM
August 16, 2023
Room: 415 AB
Location: Hilton Austin
Session Chair: Yaguo Wang, University of Texas at Austin
1:10 PM
A Hybrid Aerosol Jet Printing and Electrochemical Deposition Process for Manufacturing Multi-layer Inductors and Transformers: Lok-kun Tsui1; Yongkun Sui2; Thomas Hartmann2; Joshua Dye2; Judith Lavin2; 1University of New Mexico; 2Sandia National Laboratories
A hybrid additive manufacturing approach combining aerosol jet printing (AJP) and electrochemical deposition process was developed for manufacturing multi-layer inductors and transformers. AJP deposits metals and dielectrics with high resolution for printed electronics applications; however, nanoparticle inks have lower conductivity than bulk. Electrochemical deposition is used to address the low conductivity of the printed metal. An Ag seed layer is aerosol printed followed by the electrochemical deposition of high density, high conductivity Cu and Ni, decreasing the resistance and passivating the inductor surface respectively. We manufactured 8-layer spiral inductors with inductances of 2.5 µH. Flyback transformers consisting of 2-layer primary and 2-layer secondary spiral inductors were manufactured using this hybrid method. These transformers took an input voltage of 17V at 400 kHz and output a voltage of 1250 volts, a gain of 73.5. COMSOL modelling validated the designs. SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.
1:30 PM
Double-pulse Femtosecond Laser Sintering of Metal Nanoparticles on Flexible Substrate: Janghan Park1; Yaguo Wang1; 1The University of Texas at Austin
Selective laser sintering (SLS) is a branch of additive manufacturing, utilizing powder beds and laser irradiation. SLS is a promising manufacturing method for flexible electronics because it does not require a high-temperature environment, which is not suitable for flexible substrates. Femtosecond laser (fs-laser) has received attention due to its ultra-short irradiance time which is less than electron-phonon coupling time, resulting in minimized heat-affected zones. Despite the advantages, it has been challenged to utilize fs-laser due to a high possibility of having ablation caused by hot electron blast effects. Here, we propose double-pulse fs-laser sintering which can reduce ablation by avoiding high peak power. We verified there is a suppression of metal nanoparticle ablation with double-pulse laser for spot sintering. We plan to further develop our study from spot sintering to line sintering on flexible substrate. Lowering surface roughness and enhanced electrical properties are expected with applying double-pulse sintering.
1:50 PM
Effect of Surface State and Material on Surface Quality Enhancement by Dual Laser Powder Bed Fusion: Daniel Ordnung1; Jitka Metelkova1; Brecht Van Hooreweder1; 1KU Leuven
Parts produced by Laser Powder Bed Fusion typically exhibit a limited surface quality often requiring systematic post-processing. The KU Leuven AM team recently developed a Dual Laser Powder Bed Fusion strategy to improve the quality of inclined up-facing surfaces during building. It consists of two steps: (1) a pulsed laser induces shock waves to remove powder from inclined surfaces, followed by (2) in-situ laser remelting of the newly exposed surfaces. The first part of this paper covers the effect of the used material and initial surface state on the powder removal efficiency using shock waves. A design of experiments was performed for horizontal samples of tool steels, titanium and aluminium alloys. The second part deals with the powder removal efficiency for inclined surfaces of variable initial surface state (Ra<20µm, Ra>30µm). Finally, the third part demonstrates the surface quality improvement, resulting in a reduction of Ra by 48% for 15° inclinations.
2:10 PM
Fabrication of Crack-free Aluminum Alloy 6061 Parts using Laser Foil Printing Additive Manufacturing Process: Yu-Xiang Wang1; Chia-Hung Hung1; 1National Cheng Kung University
In this paper, aluminum alloy 6061 (AA6061) parts were fabricated using a laser foil printing (LFP) process. The process window of AA6061 in LFP was investigated to optimize the process parameter for eliminating the formation of pores and cracks. Although AA6061 is challenging for laser additive manufacturing, the optimal laser power (700 W) and scanning speed (100 mm/s) were used to fabricate AA6061 parts with a high relative density (99.8%). The line energy density was controlled properly to effectively reduce porosity and no micro-cracks were found in any LFP-fabricated AA6061 parts. The hardness, X-Ray diffraction, and tensile strength of LFP-fabricated parts were measured and compared with the original foils. The hardness was enhanced from the original foil of 41 HV to the LFP-fabricated part of 70 HV. The orientation of preference of column grains in LFP-fabricated part was [200].
2:30 PM
Identification of Nanoparticles Dispersion Mechanism in 316L Matrix Additively Manufactured By
hybrid Process of Ink Jetting and Laser Powder Bed Fusion
: Somayeh Pasebani1; Milad Ghayoor1; Joshua Gess1; Bryce Cox1; 1Oregon State University
Oxide dispersion strengthened (ODS) alloys are metal-matrix composites in which oxide nanoparticles suppress grain boundary mobility at elevated temperature; enhancing grain growth and creep resistance. In this work, two different additive manufacturing processes were proposed to disperse nanoparticles of Al2O3 into the 316L stainless steel matrix with the aid of laser powder bed fusion (LPBF), and the microstructural evolution was investigated. First, 316L SS powder and alumina particles were mixed and used as feedstock for producing 316L ODS alloy. Second, ink-jetting in the LPBF process was utilized to manufacture 316L ODS. The ink, containing Al13 nanoclusters, was selectively deposited into the 316L powder bed, and then laser consolidated metal powder and nanoclusters into nanocomposite. Detailed microstructural characterization revealed that both Al2O3 and Al13 were melted, precipitated as Al-enriched nanoparticles, and homogenously dispersed in the matrix upon solidification.
2:50 PM Break
3:20 PM
Liquid Metal Jet-on-Demand Printing of Al-6061: Eric Elton1; Kellen Traxel1; Andrew Pascall1; Jason Jeffries1; 1Lawrence Livermore National Laboratory
Many traditional aluminum alloys, including 6000 and 7000 series alloys, are difficult to additively manufacture using laser-based techniques due to hot tearing, problems with microstructure, and other issues. To avoid these problems, much effort has been placed on developing new alloys with similar properties. Here we demonstrate droplet-based printing of Al-6061 and produce nearly fully dense parts from rod feedstock. We show that by heating the build plate to sufficiently high temperatures, hot tearing can be avoided. Furthermore, by post-processing the printed parts using the traditional Al-6061 T6 heat treatment, the part microstructure and strength becomes comparable to traditionally manufactured Al-6061. Finally, we demonstrate that the tensile parts of printed tensile bars are comparable to wrought parts. This suggests that droplet based methods are a suitable way to additively manufacture Al-6061 parts with comparable properties to traditionally manufactured parts. Prepared by LLNL under Contract DE-AC52-07NA27344. LLNL-ABS-847001.
3:40 PM
Advancing the Process Window for Reliable Metal Droplet-on-demand Manufacturing: Nicholas Watkins1; Phillip Paul1; Viktor Sukhotskiy1; Jason Jeffries1; Andrew Pascall1; 1Lawrence Livermore National Laboratory
Liquid metal droplet-on-demand additive manufacturing is an attractive alternative to the industry-standard, laser-based techniques: powder-free, low feedstock footprint, minimal material waste, less contamination and inclusions from feedstock, and compatible with a large range of materials. Despite substantial ink jetting research in the past, little effort has been made to understand the parameter space to reliably eject stable, satellite-free liquid metal droplets. We previously empirically mapped the extreme region of a droplet-on-demand printability window based on the Ohnesorge and Weber jet numbers, showing that satellite-free ejections are possible for any molten metal. We continue to map an unexplored intermediate region of this window using our custom printer, finding that additional parameters to the Ohnesorge and Weber jet numbers may be needed to fully describe the printability space. This added dimensionality may permit the printability window to inform essentially any droplet-on-demand process using any feedstock. Prepared by LLNL under Contract DE-AC52-07NA27344. LLNL-ABS-846903
4:00 PM
Nanoparticle-modification of NiCu-based Alloy 400 for Laser Powder Bed Fusion: Jan-Philipp Roth1; Ivo Šulák2; Zdeněk Chlup2; Jörg Fischer-Bühner3; Ulrich Krupp4; Katrin Jahns1; 1Osnabrück University of Applied Sciences; 2Institute of Physics of Materials; 3INDUTHERM Gießtechnologie GmbH; 4Steel Institute IEHK, RWTH Aachen University
Alloy 400 is a widely used material being known for its excellent corrosive resistance. Within the chemical industry and in contrast to conventional manufacturing processes, Laser Powder Bed Fusion (LPBF) of Alloy 400 opens up for functional components that withstand harsh environments. On the basis of a holistic process route, the present work focusses on modifying the chemical composition of the base material with Titanium in order to allow the formation of TiN nanoparticles during powder production. Parameter optimization for gas atomization and LPBF is carried out and the microstructure of both powders and parts is examined. It was found that TiN nanoparticles were present along the entire manufacturing process. TiN-enhanced parts resulted in superior mechanical properties due to these fine dispersoids. Hence, nanoparticle integration proved to be feasible and effective for the present alloy system.
4:20 PM Cancelled
Diode Area Melting – A Multi-laser Alternative to Traditional Laser Powder Bed Fusion: Anqi Liang1; Mohammad Alsaddah2; Alkim Aydin2; Kristian Groom2; Kamran Mumtaz2; 1University of Southampton; 2University of Sheffield
The traditional Laser Powder Bed Fusion (LPBF) processing methodology relies on a galvo-scanning approach with high-power fiber lasers (1070nm wavelength) to selectively melt thin layers of feedstock from a powder bed. This approach creates challenges with regard to LPBF system scalability, processing efficiency (due to poor laser absorption and wall-plug efficiency) and thermal process control due to rapid melt-pool solidification. Diode Area Melting (DAM) is an alternative approach, integrating multiple individually addressable low-power fiber-coupled diode lasers into a laser head, these traverse across a powder bed to melt powdered feedstock. The highly scalable and compact diode lasers operate at a shorter wavelength (450-808nm) and lower powers (3-4W) compared to traditional LPBF fiber lasers, enabling a more efficient energy absorption with reduced cooling rates. This work presents DAM processing of Ti64 feedstock with multiple 450nm and 808nm laser sources examining effects on melt pool formation and resultant microstructures.