Corrosion Resistance of Nanosized Silicon Carbide-Rich Composite Coatings Produced by Noble Gas Ion Mixing

Abstract

Ion beam mixing has been used to produce a silicon carbide (SiC)-rich nanolayer for protective coating. Different C/Si/C/Si/C/Si(substrate) 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 1-6 × 10 ion/cm, respectively. The effects of ion irradiation, including the in-depth distribution of the SiC produced, was determined by Auger electron spectroscopy depth profiling. The thickness of the SiC-rich region was only some nanometers, and it could be tailored by changing the layer structure and the ion irradiation conditions. The corrosion resistance of the layers was investigated by potentiodynamic electrochemical test in 4 M KOH solution. The measured corrosion resistance of the SiC-rich layers was orders of magnitude better than that of pure silicon, and a correlation was found between the corrosion current density and the effective areal density of the SiC.

Design of Corrosion Resistive SiC Nanolayers

“…The detailed description of the conditions of the corrosion test can be found in ref ; its brief summary is as follows. The SiC-rich layer started to grow at the interfaces and its thickness depended on ion irradiation conditions such projectile, energy, and applied fluence and on the layer structure.…”

“…In the case of the 20–20 and 10–20 samples, only a part of the top C layer was consumed by the IBM-induced compound formation and thus the sample surface contained a carbon layer of various thicknesses. Therefore, before the corrosion test this upper carbon layer was removed by means of oxidation in microwave plasma at 500 °C for 10 min …”

“…It has also been shown that the appearance of the nanosized SiC-rich layer improves considerably the corrosion resistance of the irradiated sample . Applying various irradiation conditions on various sample structures, a correlation between the corrosion resistance of the sample and the amount and distribution of SiC determined by Auger electron spectroscopy (AES) depth profiling has been found . This observation provides the possibility of the tailoring of the corrosion resistance of a given sample; one must determine and produce the SiC amount and distribution necessary to reach the desired corrosion resistance.…”

Novel method for the production of SiC micro and nanopatterns

“…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.…”

“…Recently we have shown that it is possible to produce SiC nano-coating at room temperature by applying IBM on C/Si multilayer structures [20][21]; the produced coatings exhibited excellent corrosion resistance properties [22]. The simultaneous application of masks and ion irradiation on a properly chosen C/Si multilayer system would lead to one step compound and pattern formation.…”