Russian Researchers: Carbon Nanofibers Increase The Hardness Of Aluminum Composites

Ivan Pelevin, a researcher at the hydrocarbon catalysis and Processing Laboratory of Russia's State Research University, said: "According to the most stringent requirements, there are only two ways to improve the operability of the alloy: to create a new composite with a more complex composition, or to treat the surface of the finished product by applying an additional coating. We combine these two methods to achieve a synergistic effect of several factors in the interaction between micron alumina and carbon nanofibers.

Based on cast and 3D printed aluminum samples, surface properties can be improved by applying a composite coating by cold spraying, pereven said. The composite coating is based on a powder mixture of industrial raw materials for aluminum, with 30% pure metal particles added. In the process of synthesis, aluminum particles will be crushed when encountering hard oxides, thus filling the gaps in the structure. This combination of hard and plastic particles provides a strong bond for the coating on the surface of aluminum parts. In addition, nano carbon fibers penetrate into the space of metal powder particles, further increase the density of micro layer, greatly reduce the number of cracks and voids, and improve the hardness and strength of the coating. Adding only 1.5% carbon nanofibers can increase the hardness of the coating by 20%.

Another active factor, the researchers explained, is the high friction properties of carbon, which also contributes to the formation of a dense, defect free coating structure by "lubrication" during particle collisions. In addition, adding carbon to the coating by "self lubrication" (in-situ lubrication) can improve the friction and wear resistance.