Design of Corrosion Resistive SiC Nanolayers

Abstract

Recently, we have shown that the protecting layer of nanosize can be produced by means of ion beam mixing (IBM) of a Si/C multilayer system. The corrosion resistance of the layer correlated with the SiC amount and distribution, determined by Auger electron spectroscopy depth profiling. It has also been shown that the IBM of the Si/C system can be well described by TRIDYN simulation. By combining these two findings, it is possible to design protective layers for various arrangements of layer structure and irradiation conditions. Three different multilayer structures (with individual layer thicknesses falling in the range of 10-20 nm) have been irradiated by Ar and Xe ions at room temperature in the energy and fluence ranges of 40-120 keV and 0.25 × 10 to 6 × 10 ion/cm, respectively. The carbon and silicon depth distributions have been calculated by TRIDYN simulation. From these profiles applying a simple rule for compound formation, the SiC in-depth distributions were calculated. The resulting corrosion resistance has been measured by potentiodynamic corrosion test in 4 M KOH solution. Excellent correlation between these results and the in-depth distribution (calculated by TRIDYN simulation) of SiC has been found. Thus, the design of a protective SiC coatings operating in harsh environments is possible by applying fast and cheap simulation techniques.

Corrosion Resistance of Tungsten-Carbide-Rich Coating Layers Produced by Noble Gas Ion Mixing

“…The TRIDYN simulation cannot handle the compound formation. On the other hand, the experimental observations were similar to those in the case of the mixing of Si/C [37] which allows to make a simple model. The experimental observations: a./ unreacted W and C have only rarely found, b./ the WC concentration reached even 100% (in case of SiC it was only 80% [37]).…”

“…On the other hand, the experimental observations were similar to those in the case of the mixing of Si/C [37] which allows to make a simple model. The experimental observations: a./ unreacted W and C have only rarely found, b./ the WC concentration reached even 100% (in case of SiC it was only 80% [37]). Thus we assume that all minority C or W forms carbide and there is no limit in carbide formation.…”

“…The intermixing results in high SiC formation which is made by consuming all the carbon but it also destroys the WC layer replacing W by Si. During this process besides the formation of SiC, which exhibits also a good chemical resistance [18,37], metallic W and Si appears in the WC and SiC layers, which corrupt the chemical resistance (see later) of the sample.…”

Novel method for the production of SiC micro and nanopatterns

“…Based on experimental depth profiles measured by AES depth profiling we created a simple rule regarding the SiC compound formation: if concentration of C is lower than that of Si the whole amount of C converts to SiC and vice versa, but the amount of SiC cannot be larger than 80% (mole fraction). Therefore applying our simple rule the SiC concentration can be calculated from the results of the simulation [25].…”

“…From this 2D pattern, a 3D structure can be made utilizing the different chemical entities on the surface; the etching and/or oxidation rates of the SiC rich region is strongly different from those of Si and C [22,25]. E.gs, by etching the sample in HF/HNO3 solution for 10 min the pristine silicon layer is removed while the SiC rich region remains untouched resulting in a hole with a diameter determined by the arrangement of the SiO2 spheres (typically 600 nm) and a depth of 20 nm.…”