[求助] 镀锌件锌层破损，用环氧富锌底漆进行修补，在此处环氧富锌底漆的主要作用是屏蔽还是其中的锌粉的

chgzh0101:Sacrificial coatings, which are rich in zinc. Whenever a scratch or other damage occurs to the zinc exposed to the steel, the zinc acts as a sacrificial anode and corrodes to protect the steel surface.
以上内容是我从NACE CIP Level 1 Coating Inspector Progra .. (2013-06-04 12:00) 

我所查询的资料中也提到了

The electrochemical protection provided to steel by zinc coatings is a vital element in the effectiveness of galvanized coatings in protecting steel from corrosion.

While the potential difference between metals is the prime driving force providing the corrosion current, it is not a reliable guide to the rate and type of corrosion occurring at a particular point. The severity of galvanic corrosion also depends on the ratio of the areas of metals in contact, the duration of wetness (galvanic corrosion can only occur in the presence of a conductive solution) and the conductivity of the electrolyte. The presence of oxide films on the surface of one or both of the metals can greatly inhibit galvanic corrosion.

chgzh0101:Sacrificial coatings, which are rich in zinc. Whenever a scratch or other damage occurs to the zinc exposed to the steel, the zinc acts as a sacrificial anode and corrodes to protect the steel surface.
以上内容是我从NACE CIP Level 1 Coating Inspector Progra .. (2013-06-04 12:00) 

可是，上课时老师（老外）是这样讲的。

是否有阴极保护作用取决于所含锌粉能否形成桥接。有实验数据表明干膜内所含锌量超过92%才有可能形成桥接。
要达到这么高的含锌量，对成膜物质的选用是十分挑剔的。