Helmut Freller

Influence of intermediate layers and base materials on adhesion of amorphous carbon and metal-carbon coatings

Abstract Metal carbon (Me : C) and hydrogen-containing amorphous carbon (a-C : H) layers offer interesting possibilities for coating of tools because of their remarkable tribological features. But normally adhesion to steels used as base materials for tools is very low. A hybrid physical vapour deposition (PVD)-plasma chemical vapour deposition (PCVD) process was used to deposit zirconium (Zr)/intermediate layer/Zr : C. The a-C : H layers were deposited in a parallel plate reactor by PCVD with RF plasma. The graded Zr : C coating adheres well to various steels, very low adhesion is observed to a cobalt-containing steel and to cobalt-based hard metals. a-C : H adheres very well to silicon, glass, and aluminium (Al), but delamination in the bulk of the base material can occur due to high compressive stress. Adhesion to steel can be improved by thin layers of Al and tungsten (W), but different mechanisms seem to be the reasons for the improvement. The adhesion to hard metals increases with increasing WC content.

Deposition of ternary hard compounds with a graded composition by the use of a hybrid source ion-plating technique

Abstract Different ternary compounds consisting of two metals (type (M1 M2)X) were deposited by the use of a hybrid ion-plating deposition set-up with two cathodic sources, namely an arc source and a magnetron source. Simultaneous ablation from these two elemental metallic sources allows deposition of ternary compounds in a broad range of coating compositions without using expensive alloy sources. Deposition of graded coatings with different concentrations of the individual metals M, and M2 in the thickness of the film can be easily controlled by changing the source power of the individual sources during the deposition process. The usefulness of the process is demonstrated by deposition examples of various ternary compounds, such as (Ti, A1)N, (Ti, Cr)N, (Ti, Nb)N, (Ti, Ta)N, (Ti, W)N, (Ti, Zr)N, (Cr, A1)N, (Cr, Ta)N and (Cr, W)N.