Page 107 - 20250602 EEA QM Edition 6.0

Quality Requirements Edition 6.0 European Enamel Association

A – measuring cell of PTFE Measuring Principle
steel keep their electrical charge for some time. The Coulomb interaction between
B – electrode stamp
the negatively charged particle (powder) layer and the positively charged steel plate
C – bottom plate
will only continue as a long as the charge difference remains. After the entire loading
D – vertical adjustment
of the particles has flown off, the particles fall down. Consequently, enamel particles
E – steering rods
must have dielectric properties and have therefore a high current flow resistance.
F – clamp
Untreated enamel powder does not adhere because of the relatively high conductivity
G – ground
of the surface bound OH- groups and adsorbed water. By coating the powder with
H – diode socket
reactive Silanol components the harmful influence of the OH-groups and traces of
I – printer connection
water can be eliminated and the surface conductivity can be reduced considerably.
K – electrode connection
As a result, coated powders show an increased surface resistance of about 7 orders
L – power supply
of magnitude!
M – switch button
N – voltage control
The surface resistance is a measure of the efficiency of the particle coating.
O – resistance range
Moreover, it indicates whether the coated powder withstands any attack by humidity
P – resistance display
out of the air after ageing. Powders with a high surface resistance (>10 Ω) result in
14
good figures for the powder adhesion.

Standard Cell Commercial Measuring Unit

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