Tribological improvements of polished chemically vapor deposited diamond films by fluorination

In an effort to realize wear resistant and lubricating surfaces, polished chemically vapor deposited (CVD) diamond films are fluorinated. The effect of these films on improving frictional properties is then investigated. On fluorinated diamond surfaces, C—F bonds are formed and carbon and oxygen contents decrease. Fluorination can reduce the surface energy, as evaluated by contact angle to the water. The relationship between friction coefficient and initial Hertzian stress of polished diamond film can be expressed as one curve designated as the ‘‘master curve’’ independent of tip radius and material. Fluorination decreases friction coefficient and change of friction coefficient of polished CVD diamond with increasing load and opposing tip radius.