ThinLayerAnalysis
Chrome finished plastic shower head
The
ability to coat plastic with thin metal layers enables attractive and
complex designs to be made in a cost effective way. The
showerhead shown here is typical of such a product.
It has a very attractive mirror finish and, unlike a chrome plated
brass showerhead, it is light to handle.
The area of the showerhead investigated is near to the screw thread at
the bottom.
An initial crater was made, using a 30mm ball, through the
chrome layer, as shown below, and exposed a copper flash underlayer.
The crater is elliptical owing the fact that it was made on a
curved surface. It is a particular advantage of the ball
crater method that curved surface can be measured with ease.
The chrome layer was measured as being 3.3µm
thick.
This particular showerhead has been in
use
for about five years and has a number of scratches on it. A
apparantly significant scratch is
shown intersecting the crater wall just to the top right of centre in
the picture. However, the this is only about one micron deep
and shows the resiliance of the chrome layer to this type of damage.
A second crater was abraded, this time through both the chrome and
copper layers and into the plastic substrate.
The picture also shows the scale used to measure distances in the
micrographs in order to determine the thickness of the layers.
In this particular micrograph one unit is equivalent to
32µm on the surface, making the long axis of the ellipse
approximately 1.4mm.
The thickness of the copper flash layer was found to be
9.7µm.