Critical Issues for Chrome-free Pretreatment of Aluminium Alloys
Critical Issues for Chrome-free Pretreatment of Aluminium Alloys
Critical Issues for Chrome-free Pretreatment of Aluminium Alloys
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<strong>Critical</strong> <strong>Issues</strong> <strong>for</strong> <strong>Chrome</strong>-<strong>free</strong> <strong>Pretreatment</strong> <strong>of</strong> <strong>Aluminium</strong> <strong>Alloys</strong><br />
Testing<br />
• Most useful in<strong>for</strong>mation has been derived from carefully monitored sets <strong>of</strong><br />
test panels on exposure sites (FICARP, Alcan, TNO/ECCA)<br />
• The results <strong>of</strong> these studies correlate well with the results <strong>of</strong> fili<strong>for</strong>m<br />
corrosion tests and with certain cyclic corrosion tests like the TNO test.<br />
• The is generally poor correlation with the results <strong>of</strong> acidified salt spray tests<br />
either in terms <strong>of</strong> per<strong>for</strong>mance ranking or in the observed mode <strong>of</strong> corrosion.<br />
Low temperature ASS testing can provide good results although panels<br />
<strong>of</strong>ten develop fili<strong>for</strong>m after removal from the test cabinet.<br />
• Generally tests derived <strong>for</strong> steel substrates are not appropriate <strong>for</strong><br />
aluminium.<br />
• A simple <strong>for</strong>m <strong>of</strong> fili<strong>for</strong>m testing has been developed that can be used to<br />
optimise alloy and process route selection and to tune cleaning treatments<br />
• The exposure site condition is not reproduced in most cabinet based<br />
corrosion tests.<br />
International Conference on Environmental friendly <strong>Pretreatment</strong>s fo <strong>Aluminium</strong> and other Metals, Oslo, Norway, June 16-18, 2004
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