Corrosion and surface behaviour of cryogenically treated aluminium/fly ash composite

Deep cryogenic treatment (DCT) was performed at −196°C on aluminium/fly ash composite samples, followed by a tempering process. The corrosion behaviour and surface roughness characteristics were systematically evaluated. The corrosion rate of the tempered Al/fly ash composite (S-540) was 4.224 g/m2, whereas that of the deep cryogenically treated and tempered (DCTWT-540) sample was reduced to 2.421 g/m2. The surface roughness parameter Ra of the tempered Al/fly ash composite was 10.19 μm, while that of the DCTWT-540 sample was 7.28 μm. The Rockwell hardness (HRB) of the tempered Al/fly ash composite was 56.2 HRB, compared with 62.0 HRB for the DCTWT-560 sample. These results demonstrate that deep cryogenic treatment combined with tempering significantly reduces both the corrosion rate and surface roughness of Al/fly ash composites while simultaneously enhancing hardness relative to conventionally tempered Al/fly ash samples.