Thermal oxidative stability of Al-Mn-graphene composite material under thermocycles conditions

Aluminum-graphene composite material was synthesized by direct chemical interaction of boron carbide with molten matrix of Al-Mn alloy (analogue of АА 3003 alloy) with 1.22 wt. % of manganese, in molten alkali halides media. Initial Al-Mn alloy consists from aluminum base with formation of minor intermetallic amounts of MnAl₆, but in aluminum-graphene composite except of aluminum base by the means of XRD the additional formation of double carbide AlMn₃С. The formation of aluminum carbides was never detected no in pure aluminum, neither in all its alloys which was studied earlier. It was shown that the formation of three-layered graphene with linear dimensions up to 50 µm with total carbon concentration 0.055 wt.% decreases the onset point from 657.6℃for alloy AA3003 till 648℃for aluminum-graphene composite and results in an additional small peak at 650.1℃, which may be due to graphene oxidation. The original alloy AA 3003 in the air flow increases the mass when heated to 700℃by 0.16%, and the aluminum-graphene composite by 0.14 % which indicates a more significant oxidation of the original alloy AA 3003 compared the aluminum-graphene composite material. The effect of introduction of graphene into a metal matrix on the thermal properties of the composite was investigated, including under conditions of thermal cycling – triple heating up to 750℃and cooling up to 300℃in the air. It was shown that when graphene is introduced in the content up to 0.04 wt.% it does not change the mass of composite during thermal cycling as well as original alloy, while an increase in content up to 0.05 wt.% leads to an increase in mass of composite. Therefore, the composite material Al-Mn-graphene with a content of graphene up to 0.04 wt.%, which has higher mechanical properties compared to the alloy can be successfully used as plates of heat and radiators, since it is not subject to oxidation during thermal cycling.