Metal connection to all types of surfaces

Through such a "nano-sculpting" process, metals such as aluminum, titanium or zinc can be permanently linked with almost all other types of materials, become water-repellent surfaces, or improve their biological compatibility with the body. The variety of possible applications of these "super connections" is particularly wide, starting with metal works in industry

[Translation by Dr. Nachmani Moshe]

The way metals can be used depends mainly on the properties of their surface. A team of researchers discovered how to change the properties of the surface without affecting the mechanical stability of the metals or changing their properties. The new method is based on an electrochemical etching process during which the outermost layer of the metal is roughened at the micrometric level in a controlled manner.

Through such a "nano-sculpting" process, metals such as aluminum, titanium or zinc can be permanently linked with almost all other types of materials, become water-repellent surfaces, or improve their biological compatibility with the body. The range of possible applications of these "super connections" is extremely wide, starting from metal works in industry and ending with the development of safer implants in the field of medical technology. "The technology we used now to adapt the metal surfaces was previously known only in the field of semiconductors. Using this process in this way is completely new," said Dr. Jürgen Carstensen, one of the authors of the article. As part of the process, the surface of the metal is converted into a semiconductor, and thus can be changed as we wish. "With this method, we were able to develop an innovative process - which, unlike other digestion processes - does not damage the metal and does not affect its stability", the researcher emphasizes. "In this way, we are able to permanently join types of metals that could not be joined before, such as copper and aluminum."

The surface of metals is composed of many different types of crystals and nuclei, some of which are less chemically stable than others. These unstable particles can be specifically removed from the surface of the metal with targeted etching. The uppermost surface layer is roughened as a result of the digestion process, while creating a three-dimensional structure. This process changes the properties of the surface only, but not the metal itself. The reason for this lies in the fact that digestion occurs at a depth of only 20-10 micrometers - a layer about a quarter of the diameter of a human hair. The change that takes place as a result of the eating is noticeable: the treated surface becomes a kind of rough mesh. "If, for example, we rub a metal surface with sandpaper, even then we will get a change in appearance, however - this change occurs on a two-dimensional level only, and it does not change the properties of the surface," explains the chief researcher. With the help of the new digestion process, a three-dimensional structure with tiny protrusions is created. If you then insert a polymer that binds to each of the metals, the surfaces connect to each other in all directions like a XNUMXD attachment. "These XNUMXD connections almost never break down. In our experiments, it is usually the metal or the polymer that breaks, but not the connection itself," said Melike Baytekin-Gerngross, the lead author of the publication.

Even a thin layer of grease, such as remains on the surface after touching it with the fingers, does not affect the connection. "During our research we even applied a layer of grease to the metal surfaces. The connection still connected the surfaces", explained the lead researcher. The new method also eliminates the need for laborious cleaning of the surfaces as a preliminary step. In addition, the researchers exposed the connections to heat and humidity at extreme levels, in order to simulate the environmental conditions. These conditions also did not affect the stability of the connected surfaces. The lead researcher concludes and says: "Our connections are extremely stable and resistant to extreme weather conditions." In addition, a useful side effect of the method lies in the fact that the etching process makes the metal surfaces water repellent. The resulting lug structure functions like a densely packed XNUMXD labyrinth with no holes that can host water molecules. Therefore, in the metal lies an internal protection against fusion. "Actually, we don't know this phenomenon, that is - the lotus will come out (Lotus Effect), in pure metals without adding a water-repellent coating," explains the lead researcher.

"The range of potential applications is extremely wide, starting from the metal processing industries in the fields of ship and aircraft construction, to printing and fire protection technologies and ending in medical applications," explains the researcher. Since the nano-etching process not only produces three-dimensional structures that can be linked purely physically without the need for chemicals, the etching can also remove harmful particles from the surface, a particularly important result in medical technologies. Titanium metal is usually used in medical implants. In order to fix the titanium in place, it is necessary to add small amounts of aluminum. However, the aluminum metal itself may cause unwanted side effects in the body. "Within our process, it is possible to remove the aluminum particles from the surface of the metal layer and thereby obtain a completely clean surface, which is much more suitable for the human body. In light of the fact that we eat only the outermost layer and at a micrometric level, the stability of the implant as a whole is not impaired," explains the researcher. The researchers have so far filed four patent applications regarding their invention and various corporations dealing in the field have already expressed great interest in the innovative process and the possible applications inherent in it.

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