Pulsed laser deposition of diamond-like carbon coatings for industrial tribological applications

The aim of the present work is the investigation of the structural, mechanical and tribological properties of low-wear diamondlike carbon (DLC) coatings for industrial applications. Amorphous hydrogen-free (a-C) and hydrogenated (a-C:H) DLC coatings were coated onto various steel substrates (AISI 104511, B7, H13, D2, M2) with hardness levels varying from 28 to 66 HRC, by employing the pulsed laser deposition (PLD) method. Therefore, graphite targets were ablated with the 1064 nm wavelength of an Nd:YAG laser in argon and CA atmospheres. The high mean laser power of the applied PLD equipment guarantees deposition rates competitive to other physical vapour deposition (PVD) techniques. Because of the specific process conditions and the use of pure titanium adhesive interface layers, coatings with high adhesion to the substrates were produced at room temperature. The investigations of the coatings by means of light and scanning electron microscopy reveals the high surface quality and extremely dense coating structures. XRD measurements indicated the amorphous structure of the coatings. The nature of the chemical bonding was examined by XPS, indicating different amounts of sp(3) carbon bonds. Pin-on-disc tests against 100Cr6 ball-bearing steel balls as counterparts show an excellent wear resistance of a-C and a-C:H DLC coatings on all different steel substrates. These results, demonstrated the applicability of PLD-DLC coatings for wear protection of high precision components in the field of tools and mechanical components. (C) 2003 Elsevier Science B.V All rights reserved.