Insights into the adhesion and delamination strength of carbon films on metals by high-throughput ab initio calculations

TL;DR

This study uses high-throughput ab initio calculations to systematically analyze the adhesion and delamination strength of diamond-like carbon films on various metals, providing predictive insights and descriptors for interface stability.

Contribution

It introduces an automated computational workflow to identify trends and predict adhesion strength of diamond/metal interfaces, including a novel method for detecting surface rehybridization.

Findings

Adhesion energy correlates with the geometric mean of surface energies.

Work of separation predicts fracture location under tensile load.

Rehybridization of surface carbon indicates improved delamination resistance.

Abstract

Diamond and diamond-like carbon (DLC) coatings are widely employed for their exceptional mechanical, thermal and chemical properties, but their industrial application is often limited by weak adhesion to metallic substrates. In this work, we employ a high-throughput ab initio approach to systematically investigate the adhesion of diamond/metal interfaces, combining a set of technologically relevant metals (Al, Ag, Au, Cr, Cu, Fe, Ir, Mg, Mo, Pt, Rh, Ti, V, W, Zn) with the C(111), C(111)-2x1 (Pandey reconstructed), C(110), C(100) surfaces, that are most common in diamond and are representative of different types of bonds present in DLC. Thanks to our automated and accurate computational protocol for interface construction and characterization, databases are populated and relevant trends are identified on the effect of surface graphitization, ability to form carbides and metal reactivity on carbon film adhesion and delamination strength. Beyond capturing trends, our workflow yields predictive insights. Indeed, we found that adhesion energy scales with the geometric mean of the constituent surface energies, providing a simple descriptor for rapid screening; while comparing the work of separation with the metal's cohesive energy anticipates the fracture location under tensile loading. A novel method based on the radial distribution function g(r) analysis is introduced to identify when contact with a metal drives rehybridization of surface carbon from sp2 to sp3, the structural signature of improved resistance to delamination. These structural changes are mirrored by an electronic rearrangement at the interface, quantified by a charge-redistribution descriptor that strongly correlates with adhesion.