Surface tension, surface finish and contamination

The cleanliness of a surface is a key parameter in various industrial processes. It can be characterised by measuring the contact angle of a deposited droplet of liquid. 

We can derivate from this a whole series of information, such as:

  • Estimating the surface energy of a solid by using established models.
  • Testing the efficacy of an epilamisation process.

The measurement is taken by image analysis, in normal or micro mode.  

For practical purposes in production, we provide a system which can apply this droplet technique to inspect cleaning and epilamisation. The Jean-Pierre Renaud (JPR) system employs liquids with different surface tensions, each in a small PTFE-stoppered bottle as a reserve, and each with an oil sink comprising an oil-pike, a PTFE "agate", a flip lid covered with PTFE and elder.

Behaviour of JPR liquid droplets on a polished surface

Contaminants visible on the surface of a piece can be identified by microanalysis coupled with Scanning Electron Microscopy or in the case of compounds of organic origin, by Fourier Transform Infrared Spectroscopy (FTIR). The latter technique can be used as a one-off approach or provide a mapped view of the contaminants and their type.