2012/11/07
下面是一篇科技英语，描述的是关于Mercedes-Benz车上出现掉漆导致腐蚀现象和原因分析。
http://www.honestjohn.co.uk/forum/post/index.htm?t=49706
The rust problems on MB cars are not traditional tin worm (i.e. perforation from within) they are due to poor adhesion of the primer coating under the paint. I think the move to water-based primer coatings was around 1995.
MB used to use an epoxy-based weldable primer coating (Bonazinc) which is supposed to have a 30 year life. The snag with Bonazinc is that it has a relatively high resistance and so welder tip erosion is high. Also it needs a high curing temperature. They moved to a water-based primer to get around these problems - but unfortunately the results have turned out to be a bit 'unpredictable'. This was coupled with a move to water-based top coats and they put them on very thin (100um, as opposed to a more typical 250um). So you have a less stable primer coating and a thinner and harder top coat which made chipping more likely.
