Adhesion, tensile and shear properties of a-C/TiC interface: A first-principles study

Abstract

TiC nanocrystals in amorphous carbon (a-C) films can improve the adhesion property between a-C films and substrate. The service life of a-C films is related to the interfacial adhesion property between a-C films and TiC. However, it is difficult to explain its interfacial adhesion mechanism by experimental methods. In this paper, based on the stacking of the interface models, two a-C/TiC interface models named as the C(110)/C-edge-TiC(110) and C(110)/Ti-edge-TiC(110) interfaces were constructed by first-principles method. After relaxation, their interfacial adhesion work are 3.624 and 3.622 J/m2, and interfacial energy are 6.831 and 6.833 J/m2, respectively. The interfacial electronic characteristic of CC bond at the interface is a mixture of non-polar covalent bond and metal bond, and the CTi bond is a mixture of polar covalent bond and metal bond. The tensile strains of both the C(110)/C-edge-TiC(110) and C(110)/Ti-edge-TiC(110) interfaces in the fracture stage are ranged from 9 % to 14 %, and the fracture location of the interface models all occur in the inner of the TiC surface model near the interface. The maximum tensile stresses of the C(110)/C-edge-TiC(110) and C(110)/Ti-edge-TiC(110) interfaces are 36.873 and 36.955 GPa, respectively. Therefore, the tensile strength of the C(110)/Ti-edge-TiC(110) interface is stronger than that of the C(110)/C-edge-TiC(110) interface. The sliding potential energy maximum of the C(110)/TiC (110) interface is 0.335 J/m2, and the sliding potential barrier on the minimum energy path is 0.090 J/m2 with an ideal shear strength (τMEP) of 0.030 GPa.