Cathodic Cage Plasma Deposition of DLC Film on D2 Steel Substrate
A diamond-like carbon (DLC) film was deposited on AISI D2 substrates by a cathode cage plasma deposition technique using a plasma nitriding surface treatment/nitriding system, assembled with a graphite cage. The deposition was done at a temperature of 450°C, in a gas mixture of Ar (25%)+H2 (75%) with a deposition time of 5 hours under a constant pressure of 2 mbar. The structural analysis using SEM and optical microscopy revealed the existence of material islands arranged as clusters of approximately 20 μm in diameter, while the layer obtained has a thickness of around 4 micrometers. Microhardness tests showed hardness values of around 1300 HV, a figure much higher than that of the substrate (250 HV). With the aid of X-ray diffraction, peaks were identified as Fe3C (cementite) and carbon, in the diamond phase (DLC). Raman spectroscopy was performed in two regions: in the islands and outside them. In the islands Raman peaks from a highly crystalline structure, identified as DLC, were observed and, around these islands, those from an amorphous region identified as amorphous carbon (a-C) were seen. It was concluded that the plasma deposition process using graphite cathodic cage generated an amorphous carbon coating with crystal islands of DLC on D2 steel substrate.
De Sousa RRM, Carvalho Costa TH, Da Costa JAP, Dos Santos FEP, Nascimento IO, Souzab IA
and Viana BC