As the force increases, this track may widen. No coherent information is derived from this portion of the test. An acoustic transducer, mounted on the stylus, is used to identify the point of initiation of sample micro-cracking and senses the coating or substrate failure. It is believed that techniques can be developed to measure coating tensile strength, elastic limit, scratch resistance, friction coefficient and other physical properties. A spherical diamond is pressed against a coating surface at a constant rate of loading as the sample moves at a constant rate of travel.
Force is increased until the coating catastrophically fails.
The failure force is a measure of relative adherence for samples of similar character and thickness.