Laser Thermal Investigation on Wet Friction Material - A New Method of Non-Destructive Porosity Determination 930913
Since porosity is known to have a very significant influence on the coefficient of friction of wet friction material, a new technique was developed to determine porosity.
To measure porosity, “Laserthermographie” uses the fact, that thermal properties of any friction material are specifically influenced by pores. Any increase or decrease of the pore volume will lead to a change in heat capacity, heat conductivity and apparent density of the friction material:
Using a modulated energy source (laser) thermal waves are generated on a friction material surface. The “thermal response” of this surface is then detected by an infrared radiation detector.