Additive manufacturing of metals at small length scales – microstructure, properties and novel multi-metal electrochemical concepts
dc.contributor.author
Reiser, Alain
dc.contributor.supervisor
Spolenak, Ralph
dc.contributor.supervisor
Niederberger, Markus
dc.contributor.supervisor
Greer, Julia R.
dc.date.accessioned
2020-04-15T08:04:09Z
dc.date.available
2020-04-14T16:53:29Z
dc.date.available
2020-04-15T08:04:09Z
dc.date.issued
2019
dc.identifier.uri
http://hdl.handle.net/20.500.11850/409601
dc.identifier.doi
10.3929/ethz-b-000409601
dc.description.abstract
Many emerging applications in microscale engineering demand the fabrication of threedimensional
architectures in inorganic materials. Small-scale additive manufacturing (AM) aspires
to provide access to these geometries with feature sizes in the micro- and submicrometer range.
Yet, the synthesis of device-grade inorganic materials is still a challenge for AM, and the properties
of additively manufactured materials are typically inferior to those of materials deposited
via traditional, subtractive 2D fabrication routes – a major handicap for incorporating AM in advanced
micro- and nanofabrication processes. Materials engineering is thus necessary to improve
the quality of printed inorganic materials.
This thesis revolves around the materials science of small-scale AM of metals, focusing on both,
contemporary techniques and novel concepts introduced in this thesis. The work covers two major
topics: first, it establishes a comprehensive overview of the microstructure and properties of metals
synthesized by modern additive methods. Second, it explores new techniques that enable facile
electrochemical AM of high-quality metals and unlock multi-metal printing of chemically architected
geometries with spatially modulated properties at the submicron-scale. In combination,
these studies present a further step towards the integration of AM into modern microfabrication
routines.
The first part of the thesis defines the state of the art of small-scale metal AM, providing a detailed
literature review of current techniques and an experimental survey of their materials’ properties.
Note that the thesis in general concentrates on the study and development of methods that enable
direct additive deposition of metals. Thus, it considers indirect concepts based on the fabrication
of organic templates by two-photon lithography in combination with subsequent metallization procedures
in little detail only. Today, almost a dozen different methods are available for the direct
deposition of metal 3D geometries with a resolution better than 10 μm. As these approaches build on different physico-chemical principles, their characteristics such as feature size, speed and complexity
of printable geometries, as well as the synthesized metals and their microstructure, vary
greatly. A discussion of the individual principles and capabilities puts the concepts in perspective
to each other and projects their potentials. The thesis then presents an experimental study
on the "quality" of metals deposited by these methods. In collaboration with most of the groups
active in the field of small-scale metal AM, the thesis explores the microstructure and resulting
mechanical properties of today’s materials. On one hand, we show that metals with a wide range
of microstructures and elastic and plastic properties are synthesized. Especially electrochemical
methods deposit dense and crystalline metals with excellent mechanical properties that compare
well to those of thin-film nanocrystalline materials. On the other hand, the results reveal large
variations in materials performance that can be related to the microstructure of the individual materials.
Thus, the study provides practical guidelines for users of small-scale additive methods and
establishes a baseline for the necessary optimization of printed metals.
The second part of the thesis presents novel electrochemical AM methods that offer a spatial resolution
1 μm. First, two chapters introduce electrohydrodynamic redox printing (EHD-RP).
This technique enables the direct, ink-free fabrication of polycrystalline multi-metal 3D structures
with a resolution of 250 nm and a feature size of 100 nm. The electrochemical concept enables
outstanding as-printed materials properties (for example a strength of copper that competes with
highest values reported for nanocrystalline copper) printed at speeds that outperform current electrochemical techniques by one order of magnitude. Although neither its speed, its resolution nor
its overall materials properties are unrivaled by competing methods, EHD-RP excels in an advantageous
combination of these characteristics, readily permitting applications in microfabrication.
Additionally, as a most unique feature, EHD-RP enables multi-metal printing with unprecedented
detail. As shown, the additive control of the chemical architecture of metals with a chemical feature
size <400 nm unlocks the synthesis of 3D bi-metal structures with spatially varying microstructure
and thus locally modified properties.
The last chapter discusses the potential of tip-induced deposition in the electrochemical scanning
tunneling microscope (STM) for nanoscale AM. A strong confinement of deposition below the
nanometer-sized probe enables 2D patterning of cobalt with a feature size of 50 nm. The potential
for 3D printing is demonstrated, but reliable 3D fabrication is hampered by unsatisfactory
stability of employed gold STM probes. Consequently, the chapter concludes with the development
of more stable Pt and Pt-20at.%Ir probes, readying the designed setup for true 3D deposition.
Nevertheless, a low deposition speed, a narrow processing window and a comparably complex
instrumentation are identified as significant challenges for the proposed concept.
In conclusion, the thesis experimentally identifies materials challenges for contemporary smallscale
AM of metals but at the same time presents a potential solution by introducing EHD-RP – an
electrochemical concept that offers ink-free printing of high-quality metals. Additionally, the
demonstrated multi-metal printing with submicrometer resolution sketches a route towards the
bottom-up fabrication of chemically designed 3D devices and materials with properties tuned at
single-voxel level – staking out a niche for small-scale AM as an enabling technology for chemically
architected, inorganic materials that could spark the development of novel materials for e.g.
catalysis, active chemical devices, sensors, or metamaterials that combine architected geometry
and chemistry.
en_US
dc.format
application/pdf
en_US
dc.language.iso
en
en_US
dc.publisher
ETH Zurich
en_US
dc.rights.uri
http://rightsstatements.org/page/InC-NC/1.0/
dc.subject
Additive manufacturing
en_US
dc.subject
Electrochemistry
en_US
dc.subject
3D printing
en_US
dc.subject
Microscale
en_US
dc.subject
Nanoscale
en_US
dc.subject
Mechanical properties
en_US
dc.subject
Microstructure
en_US
dc.subject
Metals
en_US
dc.title
Additive manufacturing of metals at small length scales – microstructure, properties and novel multi-metal electrochemical concepts
en_US
dc.type
Doctoral Thesis
dc.rights.license
In Copyright - Non-Commercial Use Permitted
dc.date.published
2020-04-15
ethz.size
330 p.
en_US
ethz.code.ddc
DDC - DDC::5 - Science::500 - Natural sciences
en_US
ethz.identifier.diss
26184
en_US
ethz.publication.place
Zurich
en_US
ethz.publication.status
published
en_US
ethz.leitzahl
ETH Zürich::00002 - ETH Zürich::00012 - Lehre und Forschung::00007 - Departemente::02160 - Dep. Materialwissenschaft / Dep. of Materials::02645 - Institut für Metallforschung / Institute of Metals Research::03692 - Spolenak, Ralph / Spolenak, Ralph
en_US
ethz.relation.continues
20.500.11850/190707
ethz.relation.isSourceOf
10.3929/ethz-b-000339619
ethz.date.deposited
2020-04-14T16:53:38Z
ethz.source
FORM
ethz.eth
yes
en_US
ethz.availability
Open access
en_US
ethz.rosetta.installDate
2020-04-15T08:04:25Z
ethz.rosetta.lastUpdated
2021-02-15T10:13:22Z
ethz.rosetta.versionExported
true
ethz.COinS
ctx_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:journal&rft.atitle=Additive%20manufacturing%20of%20metals%20at%20small%20length%20scales%20%E2%80%93%20microstructure,%20properties%20and%20novel%20multi-metal%20electrochemical%20concepts&rft.date=2019&rft.au=Reiser,%20Alain&rft.genre=unknown&rft.btitle=Additive%20manufacturing%20of%20metals%20at%20small%20length%20scales%20%E2%80%93%20microstructure,%20properties%20and%20novel%20multi-metal%20electrochemical%20concepts
Dateien zu diesem Eintrag
Publikationstyp
-
Doctoral Thesis [30188]