Detect the thickness of metal or oxide coating on the surface of the material. Detection methods are:

 

Metallographic method: enlarge coating thickness by using the principle of metallographic microscope, in order to accurate observation and measurement.

 

Coulomb method: dissolving accurate finite area coating by using appropriate electrolyte anodic dissolution, the coating dissolved completely when the electrolytic cell voltage changes dramatically, and calculate the coating thickness through the consumption of electricity. The coating consumes different quantity of electric owing to the different dissolution methods. It can be calculated by the experiment began to end time when dissolved with a constant current density. And calculated by power consumption when dissolved with a nonconstant current density.

 

X - ray method:

 

It is based on the strong and narrow beam of polychromatic X-ray interaction with substrate and coating to determine coating thickness.