SiC multi-layer protective coating on carbon obtained by thermionic vacuum arc method

Abstract

SiC single-layer or multi-layer on C used to improve the oxidation resistance and tribological properties of C have been obtained by Thermionic Vacuum Arc (TVA) method. The 200nm thickness carbon thin films was deposed on glass or Si substrate and then 100÷500 nm thickness SiC successively layers on carbon thin film was deposed. The microstructure and mechanical characteristics of as-prepared SiC coating were investigated by Transmission Electron Microscopy (TEM, STEM), Energy Dispersive X-Ray Spectroscopy (EDS), Electron Scattering Chemical Analysis (ESCA) and tribological techniques.Samples containing SiC single-layer or multi-layer coating on carbon were investigated up to 1000 o C. The results of thermal treatments reveals the increase of oxidation resistance with increase of the number of SiC layers. The mechanism of oxidation protection is based on the reaction between SiC and elemental oxygen resulting SiO 2 and CO.The tribological behavior of SiC coatings was evaluated with a tribometer with ball-on-disk configuration from CSM device with 6mm diameter sapphire ball, sliding speed in dry conditions being 0.2m/s, with normal contact loads of 0 .5N, 1N, 1.5N and 2N, under unlubricated conditions. The friction coefficient on SiC was compared with the friction coefficient on uncoated carbon layer.Electrical surface resistance of SiC coating on carbon at different temperatures was measured comparing the potential drop on the sample with the potential drop on a series standard resistance in constant mode.

Thermionic Vacuum Arc—A Versatile Technology for Thin Film Deposition and Its Applications

“…1-cathode, 2crucible 3-material to be deposited 4-holder with substrates 5-thickness monitor This simplest arrangement, one electron gun and one crucible, is applicable also in cases when the intention is to deposit a film from several materials, which can be put together into one crucible; see e.g., ref. [36][37][38][39][40].…”

“…In ref. [37][38][39][40] were studied silicon-carbide multilayer protective coatings at temperatures up to 1000 • C. Measurements showed that the third layer acts as a stopping layer for oxygen. Characterization of ternary C-Si-Al nanocomposite thin films obtained by TVA presented in [122].…”