In Situ Synthesis of Cr2AlC Gradient Coating by Plasma Transferred Arc Cladding

The high-purity MAX phase coatings with thickness lower than 10 μm are mainly deposited by physical vapor deposition. Still, they typically fail to meet the long-term stability demand of heavy load and high-temperature applications. In the present study, a process for in situ synthesis of Cr 2 AlC MAX phase coating based on plasma transferred arc cladding directly from pure Cr, Al and Cr 3 C 2 powder has been proposed for the first time. The as-received powders were mixed at a molar ration Cr:Al:C = 2:1.1:1 in a mortar manually for 1800s. To reveal the possible in situ synthesis mechanism, the effects of the plasma gas flux on the phase formation and microstructure evolution of coatings were investigated. The results indicated that a Cr 2 AlC gradient coating with a 1 mm high-purity Cr 2 AlC top layer was formed on low-carbon steel by plasma gas flux 0.03 and 0.04 L/s. If plasma gas flux continued to increase to 0.05 L/s, no Cr 2 AlC MAX phase was observed in the coating. The study proved the possibility of in situ synthesis of Cr 2 AlC coating by plasma transferred arc cladding and revealed the in situ synthesis mechanism.