A research program has been developed to characterize the corrosion behavior of the metals most widely used in solar collector systems. Common heat transfer fluids such as glycol/water solutions show a low aggressivity, unless pollution or high temperature exposure (degradation) occur. This paper deals with the study of the corrosion behavior of the aluminium alloy 6351 (nominal composition: 1 percent Si, 0. 6 percent Mg, 0. 3 percent Mn, the balance Al) in ethylene or propylene glycol (EG or PG)/water solutions (1:1 in volume) degraded at 108 degree C in contact with AA 6351 as glycol oxidative degradation catalyzer. The tests in degraded solutions, performed at 80 degree C over a period of 60 days, showed that degradation causes an increase in the uniform corrosion rates and a remarkable pitting attack. Pitting corrosion has been mainly attributed to the action of copper ions dissolved from the alumunium alloy and detected in the solutions by atomic adsorption analysis.
Corrosion behaviour of AA 6351 in glycol/water solutions degraded at elevated temperature
MONTICELLI, Cecilia;BRUNORO, Giancarlo;FRIGNANI, Alessandro;ZUCCHI, Fabrizio
1988
Abstract
A research program has been developed to characterize the corrosion behavior of the metals most widely used in solar collector systems. Common heat transfer fluids such as glycol/water solutions show a low aggressivity, unless pollution or high temperature exposure (degradation) occur. This paper deals with the study of the corrosion behavior of the aluminium alloy 6351 (nominal composition: 1 percent Si, 0. 6 percent Mg, 0. 3 percent Mn, the balance Al) in ethylene or propylene glycol (EG or PG)/water solutions (1:1 in volume) degraded at 108 degree C in contact with AA 6351 as glycol oxidative degradation catalyzer. The tests in degraded solutions, performed at 80 degree C over a period of 60 days, showed that degradation causes an increase in the uniform corrosion rates and a remarkable pitting attack. Pitting corrosion has been mainly attributed to the action of copper ions dissolved from the alumunium alloy and detected in the solutions by atomic adsorption analysis.I documenti in SFERA sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
