Thin, hard ceramic coatings on metals & ceramics are extensively used for wear & abrasion resistance, friction control, corrosion resistance, & tailored functional (electrical, optical & magnetic) properties across a wide range of high performance applications. Coating producers & users have to measure & control the coating-substrate adhesion strength, because adhesion failure is often the primary failure mechanism of the coating, limiting its performance & life. The quantitative test method of choice for thin hard coatings is scratch adhesion testing. In this technique, a diamond stylus is drawn across the coating on the surface under increasing normal load & the damage to the coating is assessed against the applied load. With DOE funding, & in coordination with ASTM Committees, a new scratch adhesion test standard has been published, ASTM C1624.
