A graphene and nickel coating will enhance the strength of components used in aviation and medical applications.

A protective layer made from a composite of graphene and nickel enhances the strength of the metal surface it is applied to. This conclusion was reached by scientists through computer simulations. They demonstrated that even a thin composite coating (just one nanometer thick) nearly doubles the strength of the metal surface, while a five-nanometer thick coating increases strength by four times. However, it was noted that the plasticity of the metal surface decreases as the coating thickness increases. These findings will facilitate the development of materials with adjustable strength, paving the way for their use as coatings on metal surfaces in aerospace, medical, and industrial applications.

2024-10-22 07:31:53https://naked-science.ru/article/column/pokrytie-iz-grafena-i-nik

The results of the study, supported by a grant from the Presidential program of the Russian Science Foundation (RSF), have been published in the journal Surfaces and Interfaces.

Metal surfaces of machine components and instruments wear out during operation. To reduce wear, they can be coated with composites based on graphene with metal particles (for instance, aluminum, nickel, and copper). This enhances the wear resistance and corrosion resistance of metal surfaces, making it widely used in electronics, machine engineering, and instrumentation. However, it is crucial not only to protect the surface of critical components but also to strengthen it. Therefore, scientists are striving to determine the optimal thickness of the composite for effective strengthening and protection of metal surfaces in devices.

Researchers from the Institute of Problems of Superplasticity of Metals of the Russian Academy of Sciences (Ufa) have developed a mathematical model to study the properties of composites made from graphene and nickel nanoparticles. Initially, the research team modeled the synthesis process of the composite, where graphene and nickel nanoparticles are mixed and compressed at 727°C and at a pressure four times higher than atmospheric pressure. These conditions were selected because earlier studies have shown that a strong composite structure is formed under such conditions.

Next, the scientists modeled the application of the composite onto the surface of nickel. They chose this metal specifically because it has good resistance to corrosion and oxidation by oxygen and has properties similar to titanium, which is widely used in engineering. Titanium is an extremely expensive metal, while nickel, although cheaper, has lower strength compared to titanium. Therefore, to enable nickel to compete in strength with titanium, the researchers decided to strengthen its surface with a graphene composite.

The authors examined protective layers of varying thicknesses—from one to 5.1 nanometers—to understand how this parameter affects the strength and plasticity of the sample. Composite coatings thicker than 5.1 nanometers were not investigated by the scientists, as they assumed that further increasing the thickness would result in negligible changes in tensile strength and plasticity. This assumption was made because the strength of the nickel surface with a coating thickness of 5.1 nanometers was close to the strength of pure composite based on graphene and nickel, representing the maximum possible value.

Modeling showed that the thicker the composite coating, the harder it is to break the sample. For example, the tensile strength of the nickel surface with a protective layer of five nanometers was 15 percent greater than that of a sample with a one-nanometer coating. Moreover, increasing the coating thickness from one to two nanometers resulted in a four percent decrease in plasticity. Beyond that thickness, plasticity remained nearly unchanged. Such composite coatings will make machine parts—such as gas turbine engines—stronger, while the hulls of spacecraft will be less susceptible to external impacts.

“We chose this type of coating for application on metals because the composite provides machine and instrument components with high strength and wear resistance. It will also protect metals from scratches and impacts. All these results from years of work on creating composites will help reduce wear on metal surfaces. In the future, we plan to study the practical application of composites with properties we already know,” says project leader, supported by an RSF grant, Yulia Baimova, Doctor of Physical and Mathematical Sciences, Professor of the Russian Academy of Sciences, and Head of the Youth Laboratory of "Physics and Mechanics of Carbon Nanomaterials" at the Institute of Problems of Superplasticity of Metals.