DEPOSITION OF WEAR-RESISTANT ALN-DIAMOND COMPOSITE COATINGS

We have prepared composite coatings of aluminum nitride (AIN) and diam ond on silicon, copper and steel substrates and investigated their tri bological properties. To control interfacial stresses, the coatings ar e prepared with a novel microstructure in which diamond forms a cellul ar network in a background matrix of AlN. This type of microstructure also imparts enhanced toughness and adhesion properties. Owing to matc hing of temperature variation in thermal expansion coefficients of AIN and diamond, thermal stresses within the compostie films are minimize d while substrate-composite interfacial stresses are effectively accom odated in the background matrix of AIN, which is relatively softer tha n diamond. Selective abrasion and indentation measurements are carried out to investigate the utility of coatings for wear protection. The i mportance of AlN as a component material for forming high quality diam ond composites is discussed.