Ask the Expert Question-and-Answer Archive
(Hard Chrome Plating)
by Randy Taylor, Advanced Tooling Corporation
X-ray vs. SEM testing
Q. We are getting mixed results on our plating thickness tests. Plating is 55 microinches of Type II Gold over 220 Microinches electroless nickel. Base metal is 360 Brass.
Can you tell me which of the 2 testing methods listed below is more accurate? X-Ray or Scanning Electron Microscope (SEM)
A. X-rays provide non-destructive thickness checks by giving you an average value over a wide swath. The equipment requires calibration and interpretation.
SEM? I'm assuming that your equipment requires a photo-micrograph cross section of the coating on parts or specimens from which a measurement is taken.
I would presume that, albeit destructive, SEM which provides a direct visual measurement is the most accurate.