Adhesion measurement of zirconium nitride and amorphous silicon carbide coatings to nickel and titanium alloys

Polycrystalline ZrN and amorphous Si0.57C0.43 coatings were deposited by ca thodic are evaporation and by plasma-assisted chemical vapor deposition (PA CVD) respectively on Incoloy 825 (Inc. 825), Hastelloy C22 (Hast. C22) and Titanium Grade 12 (Ti. 12) substrates. Scratch tests were employed to asses s the critical load for interfacial failure and fracture mechanisms for the various coating systems. Critical loads, characterized by continuous delam ination of the coating, occurred at 41.2 N, 44.1 N and 29.4 N for ZrN depos ited on Hast. C22, Inc. 825 and Ti. 12 respectively. Interfacial failure of the Si0.57C0.43-coated metallic substrates was dominated by brittle fractu re of the Si0.57C0.43 coating. Critical loads of 2.9 N, 3.9 N and 6.8 N wer e obtained for Si0.57C0.43 deposited on Inc. 825, Hast. C22 and Ti. 12 resp ectively. Work of adhesion values were calculated from two well-known model s, namely the Bull-Rickerby and Laugier models, and from a model that incor porates elastic-plastic indentation. The ranking of the adhesion for the co ating-metal substrate combinations is (from best to worst): ZrN-Inc. 825, Z rN-Hast. C22, ZrN-Ti, Si0.57C0.43-Ti, Si0.57C0.43-Hast. C22 and Si0.57C0.43 -Inc. 825. (C) 1999 Published by Elsevier Science S.A. All rights reserved.