Corrosion behavior of aluminium composite coatings
- Univ. of South Australia (Australia). Ian Wark Research Inst.
- Commonwealth Scientific and Industrial Research Organization (Australia). Div. of Mfg. Technology
The corrosion behavior of metal-matrix composite (MMC) coatings (3 mm to 5 mm [0.12 in. to 0.2 in.] thick) fabricated by the plasma-transferred arc (PTA) surfacing process was investigated by potentiostatic and immersion techniques. The test electrolyte was a 3.5 wt% sodium chloride (NaCl) solution. Composites were reinforced with angular particles of aluminum oxide (Al{sub 2}O{sub 3}), silicon carbide (SiC), or titanium carbide (TiC) of varying volume fractions (V{sub f} {approx} 2.5% to 40%) and of two sizes (70 {micro}m and 140 {micro}m). The matrix was predominantly aluminium with 2 wt% Ni, which was added to enhance the matrix`s wear resistance. The reinforcement type significantly influenced corrosion behavior of the MMC coatings. The immersion study showed the corrosion rate increased in the following order of reinforcement addition: Al{sub 2}O{sub 3} < SiC < TiC. Al{sub 2}O{sub 3} particles appeared to play no role in the corrosion process, whereas SiC and TiC particles participated actively. Reinforcement surface area appeared to be a significant parameter influencing the corrosion mechanism of the SiC- and TiC-reinforced composites. An increase in V{sub f} generally resulted in a higher corrosion rate for the SiC- and TiC-reinforced composites. Coating porosity, electrical conductivity of the reinforcement, and the presence of nickel aluminide (NiAl{sub 3}, formed during the surfacing process) all influenced corrosion behavior.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 556415
- Journal Information:
- Corrosion, Vol. 53, Issue 11; Other Information: PBD: Nov 1997
- Country of Publication:
- United States
- Language:
- English
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