Nickel Formation on Graphite Sheet Surface for Improving Wettability with Magnesium Alloy

Abstract

Magnesium-calcium alloy-based composites reinforced with vapor grown carbon fibers (VGCFs) are supposed to possess satisfactory high-temperature applications. However, poor wettability of magnesium with carbon fiber is a technical problem encountered in fabrication of the composites. In order to cover the wetting problem, wetting behavior of magnesium alloys on graphite sheet, pure nickel, and nickel coated graphite sheet were investigated using sessile drop method. The graphite was non-wetting by both Mg-5Al alloy and Mg-5Al-3Ca alloy with contact angles about 120°. The droplet of magnesium alloys on nickel plate spread rapidly. Contact angle of Mg-5Al-3Ca alloy decreased from about 94°to 43°. Wettability of magnesium alloys on nickel coated graphite sheet was improved through the dissolution of nickel into the liquid magnesium alloy. Calcium addition showed negative effect on contact angle of nickel substrate, and also slightly hindered the spread of magnesium alloy droplet on nickel coated graphite sheet.

Fabrication of Vapor-Grown Carbon Fiber-Reinforced Magnesium-Calcium Alloy Composites by Compo-Casting Process

“…This alloy was fabricated by permanent mold casting using the following chemical composition (mass%): 4.62 Al and 2.95 Ca, with the balance Mg, as described in Ref. 22). The Mg-5Al alloy was also fabricated for comparison.…”

“…Then, the slurry was again heated to a fully liquid state and mechanically mixed, which further dispersed the Ni-coated VGCF clusters. Moreover, according to our previous work, 22) a nickel coating on graphite improves the wettability of a magnesium alloy through the dissolution of nickel into the liquid magnesium alloy. With nickel coatings diffused into the metal, a homogeneous VGCF distribution and high bond strength with the matrix were obtained.…”

“…Our previous study revealed that an improvement in the wettability of a magnesium alloy on a nickel-coated graphite sheet was achieved through the dissolution of the nickel into the liquid magnesium alloy. 22) In this study, Ni-coated VGCF-reinforced Mg-Al-Ca alloy composites were fabricated using a compo-casting process. Then, the effects of the Ni-coated VGCFs on the microstructure and mechanical properties of the magnesium alloy were investigated, as well as the strengthening mechanism of the Ni-coated VGCF-reinforced Mg-Al-Ca alloy composites.…”

Lightweight metallic matrix composites: Development of new composites material reinforced with carbon structures

“…The production of MMC materials with these types of structures can be achieved with different techniques, for example additive manufacturing, casting, and powder metallurgy, as extensively studied by Saboori et al 5,6 Despite these advantages, the production of MMC still has some issues-such as poor wettability between carbon and molten metals or chemical reactions during the manufacturing process-that can lead to the formation of some brittle products phases that may reduce physical properties of the composites. 7 Functional coating, obtained by various processes, 8,9,10 is one of the most promising techniques to protect fibers and to enhance the interaction with the molten matrix. In particular, metallic coating is the best candidate to overcome difficulties due to the production process of composites: in fact, molten metals can easily wet solid metals, and the formation of brittle phases because of chemical reactions is less probable.…”