Nanostructured 2024Al–SiC_p composite coatings

Abstract

The microstructure and mechanical properties of plasma sprayed nanostructured 2024Al alloy were investigated before and after adding SiC particles on weathering steel (Cor-Ten A242) substrate. Mechanical alloying (MA) was used to synthesise the nanostructured 2024Al and 2024Al–15 wt-%SiC composite powders. X-ray diffraction studies showed SiC_p embedment in the Al matrix after MA and nanograins in the MA powder and coatings. It was found that the porosity level in the coating was reduced to 2% and the coating hardness was increased to 3276 MPa. The high adhesion strength of the coatings observed can be attributed to the higher degree of diffusion at the interface. In these experiments, there was 60% decrease in the wear rate of the coatings. Results show that MA decreases the size of the matrix grains to 45 nm for the MA powder and 17 nm for the coating. The results of mechanical and wear tests also indicate that MA and the addition of SiC particles increased the strength, hardness and wear resistance of 2024Al and remarkably decreased its ductility.

Keywords:

• 2024 aluminium alloy
• Metal matrix composites (MMCs)
• Mechanical alloying (MA)
• Adhesion
• Wear
• Plasma spray coatings

Acknowledgement

The work was carried out with financial support from the Ministry of Education and Science of the Russian Federation in the framework of Increase Competitiveness Program of NUST ‘MISiS’ (No. k4–2014–081).