Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


Breakthrough in materials science: Kiel research team can bond metals with nearly all surfaces


How metals can be used depends particularly on the characteristics of their surfaces. A research team at Kiel University has discovered how they can change the surface properties without affecting the mechanical stability of the metals or changing the metal characteristics themselves. This fundamentally new method is based on using an electro-chemical etching process, in which the uppermost layer of a metal is roughened on a micrometer scale in a tightly-controlled manner. Through this “nanoscale-sculpturing” process, metals such as aluminium, titanium, or zinc can permanently be joined with nearly all other materials, become water-repellent, or improve their biocompatibility.

The potential spectrum of applications of these “super connections” is extremely broad, ranging from metalwork in industry right through to safer implants in medical technology. Their results have now been published in the prestigious journal “Nanoscale Horizon” of the Royal Society of Chemistry.

The targeted etching process of “nanoscale-sculpturing” roughens the upper layer of metal (here aluminium, 20 µm = 0.02 mm), thereby creating a 3D-structure with tiny hooks.

Melike Baytekin‐Gerngroß

“We have now applied a technology to metals that was previously only known from semiconductors. To use this process in such a way is completely new,” said Dr. Jürgen Carstensen, co-author of the publication. In the process, the surface of a metal is converted into a semiconductor, which can be chemically etched and thereby specifically modified as desired.

“As such, we have developed a process which – unlike other etching processes – does not damage the metals, and does not affect their stability,” emphasised Professor Rainer Adelung, head of the “Functional Nanomaterials” team at the Institute for Materials Science. Adelung stressed the importance of the discovery: “In this way, we can permanently connect metals which could previously not be directly joined, such as copper and aluminium.”

How does the “nanoscale-sculpturing” process work exactly?

The surfaces of metals consist of many different crystals and grains, some of which are less chemically stable than others. These unstable particles can be specifically removed from the surface of a metal by a targeted etching. The top surface layer is roughened by the etching process, creating a three-dimensional surface structure. This changes the properties of the surface, but not of the metal as a whole. This is because the etching is only 10 to 20 micrometers deep – a layer as thin as a quarter of the diameter of human hair. The research team has therefore named the process “nanoscale-sculpturing”.

The change due to etching is visible to the naked eye: the treated surface becomes matt. “If, for example, we treat a metal with sandpaper, we also achieve a noticeable change in appearance, but this is only two-dimensional, and does not change the characteristics of the surface,” explained Dr. Mark-Daniel Gerngroß of the research team on materials sciences from Kiel.

Through the etching process, a 3D-structure with tiny hooks is created. If a bonding polymer is then applied between two treated metals, the surfaces inter-lock with each other in all directions like a three-dimensional puzzle. “These 3-D puzzle connections are practically unbreakable. In our experiments, it was usually the metal or polymer that broke, but not the connection itself,” said Melike Baytekin-Gerngroß, lead author of the publication.

Surfaces with multifunctional properties

Even a thin layer of fat – such as that left by a fingerprint on a surface – does not affect the connection. “In our tests, we even smeared gearbox oil on metal surfaces. The connection still held,” explained Baytekin-Gerngroß. Laborious cleaning of surfaces, such as the pre-treatment of ships' hulls before they can be painted, could thus be rendered unnecessary.

In addition, the research team exposed the puzzle connections to extreme heat and moisture, to simulate weather conditions. This also did not affect their stability. Carstensen emphasised: “Our connections are extremely robust and weather-resistant.” A beneficial side-effect of the process is that the etching makes the surfaces of metal water-repellent. The resulting hook structure functions like a closely-interlocked 3D labyrinth, without holes which can be penetrated by water. The metals therefore possess a kind of built-in corrosion protection. “We actually don't know this kind of behaviour from metals like aluminium. A lotus effect with pure metals – i.e. without applying a water-repellent coating – that is new,” said Adelung.

Potentially limitless applications

“The range of potential applications is extremely broad, from metalworking industries such as ship-building or aviation, to printing technology and fire protection, right through to medical applications,” said Gerngroß. Because the “nanoscale-sculpturing” process not only creates a 3D surface structure, which can be purely physically bonded without chemicals – the targeted etching can also remove harmful particles from the surface, which is of particularly great interest in medical technology.

Titanium is often used for medical implants. To mechanically fix the titanium in place, small quantities of aluminium are added. However, the aluminium can trigger undesirable side-effects in the body. “With our process, we can remove aluminium particles from the surface layer, and thereby obtain a significantly purer surface, which is much more tolerable for the human body. Because we only etch the uppermost layer on a micrometer scale, the stability of the whole implant remains unaffected,” explained Carstensen.

The researchers have so far applied for four patents for the process. Businesses have already shown substantial interest in the potential applications. “And our specialist colleagues in materials sciences have also reacted enthusiastically to our discoveries,” said a delighted Adelung.

Original publication:
M. Baytekin-Gerngross, M.D. Gerngross, J. Carstensen and R. Adelung: Making metal surfaces strong, resistant, and multifunctional by nanoscale‐sculpturing. Nanoscale Horizon. DOI: 10.1039/C6NH00140H!divAbstract

Photos are available to download:
Caption: A strip of aluminium – the surface of which has been treated with an electro-chemical etching process – is permanently bonded with thermoplastic by heating.
Photo/Copyright: Julia Siekmann / Kiel University
Caption: Large metal surfaces can also be treated with nanoscale sculpturing. Although the etching is only applied to a thin layer on a micrometer scale, the resulting change is visible to the naked eye: the treated surface of the aluminium in the foreground has become matt.
Photo/Copyright: Julia Siekmann / Kiel University
Caption: The Kiel-based research team of Melike Baytekin-Gerngroß (on the left), Mark-Daniel Gerngroß, Jürgen Carstensen and Rainer Adelung compares test results in the laboratory.
Photo/Copyright: Julia Siekmann / Kiel University
Caption: Aluminium plates which have only been sandblasted (in the background of the picture) cannot be glued successfully. The two glued plates separate again at the interface between glue and metal – this can be seen by the fact that there is no white glue residue visible on one of the two plates.
The aluminium plates in the foreground of the picture were treated with the etching process “nanoscale-sculpturing” before being glued. These plates could also be separated. But the white glue particles left on both plates demonstrate that the bond between metal and glue is not broken, but rather the glue itself.
Photo/Copyright: Julia Siekmann / Kiel University
The targeted etching process of “nanoscale-sculpturing” roughens the upper layer of metal (here aluminium, 20 µm = 0.02 mm), thereby creating a 3D-structure with tiny hooks. A surface treated with this process can inter-lock like a three-dimensional puzzle with the surfaces of almost all other materials, forming unbreakable bonds. With this method, it is even possible to create bonds between aluminium and copper.
Photo/Copyright: Melike Baytekin‐Gerngroß
The roughened surface structure of zinc in 10,000x magnification (2 µm = 0.002 mm).
Photo/Copyright: Melike Baytekin‐Gerngroß

Prof. Dr. Rainer Adelung
Functional Nanomaterials
Institute for Materials Science
Kiel University
Tel.: +49 (0)431/880-6116

Dr. Jürgen Carstensen
Functional Nanomaterials
Institute for Materials Science
Kiel University
Tel. +49 (0)431/880-6181

Dr. Boris Pawlowski | Christian-Albrechts-Universität zu Kiel

More articles from Materials Sciences:

nachricht From ancient fossils to future cars
21.10.2016 | University of California - Riverside

nachricht Study explains strength gap between graphene, carbon fiber
20.10.2016 | Rice University

All articles from Materials Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

Im Focus: New Products - Highlights of COMPAMED 2016

COMPAMED has become the leading international marketplace for suppliers of medical manufacturing. The trade fair, which takes place every November and is co-located to MEDICA in Dusseldorf, has been steadily growing over the past years and shows that medical technology remains a rapidly growing market.

In 2016, the joint pavilion by the IVAM Microtechnology Network, the Product Market “High-tech for Medical Devices”, will be located in Hall 8a again and will...

Im Focus: Ultra-thin ferroelectric material for next-generation electronics

'Ferroelectric' materials can switch between different states of electrical polarization in response to an external electric field. This flexibility means they show promise for many applications, for example in electronic devices and computer memory. Current ferroelectric materials are highly valued for their thermal and chemical stability and rapid electro-mechanical responses, but creating a material that is scalable down to the tiny sizes needed for technologies like silicon-based semiconductors (Si-based CMOS) has proven challenging.

Now, Hiroshi Funakubo and co-workers at the Tokyo Institute of Technology, in collaboration with researchers across Japan, have conducted experiments to...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Resolving the mystery of preeclampsia

21.10.2016 | Health and Medicine

Stanford researchers create new special-purpose computer that may someday save us billions

21.10.2016 | Information Technology

From ancient fossils to future cars

21.10.2016 | Materials Sciences

More VideoLinks >>>