抄録
The effects of Cl ion on deposition mechanism and film properties in electrophoretic coating bath of water soluble alkyd primer were studied on steel and aluminum alloys, and the following conclusions were drawn.
(1) In aluminum alloys, the amount of deposition at first remarkably increased with the increase in addition of Cl ion and attained to maximum, and then, decreased. The above phenomena can be explained by the following reason: the increase in deposition amount in the first range was attributed to the prevention of passivity of anode during electrophoresis and the decrease in that amount in the next range was attributed to the increase in film resistance due to the dissolution of anode caused by the addition of Cl ion.
(2) In steel, there is no range of increase in deposition amount due to the addition of Cl ion, because of no passivity of anode. The amount of deposition gradually increased from the outset. The above phenomenon may be attributed to the increase in film resistance due to the dissolution of anode caused by the addition of Cl ion.
(3) In aluminum alloys, the oxidized film on anode formed during electrodeposition had considerable corrosion resistance.
(4) The properties of coated film, both chemical and physical, were not affected by the addition of Cl ion in the range of 0-70ppm.
