Nowadays plasma techniques are getting more and more involved in production technologies because the traditional chemical treatments are sometimes less feasible and/or environmentally harmful. Besides the plasma pre-treatments, the plasma technology can also be utilized to develop thin protective layers. Day by day new techniques come into sight, so the categorization and review of them is an important task, which was the primary aim in this paper by trying to make an account on the most up-to-date ones. In this way, some important characteristic features and major advantages are presented here for the plasma treatment of plastic surfaces under ambient atmosphere, ultrafine surface cleaning with low-pressure plasma sources, and an example for the RF-PACVD deposition of protective and highly corrosion resistant thin glassy layers by plasma polymerization of HMDSO precursors. Envisaged future utilization of a small-scale atmospheric pressure plasma (APP) jet system installed in the Laboratory of Surface Techniques at University of Miskolc is also discussed.

In this study, the structure of Zr4/Cr3 based conversion coating on aluminium alloys was studied by using the Glow Discharge-Optical Emission Spectroscopy (GD-OES) method. Samples were examined before and after exposure to high vacuum. The results revealed that the structure of the coating has two different phases, solute and gelatinous state. The growth kinetics of conversion coating is investigated by considering the thickness of the coating under various immersion times inside the coating bath. The present data suggest that coating growth kinetics has five different states, namely activation, linear growth, limited growth, saturation limit and detachment state. The conversion coating structure over aluminium alloys such as AA2024 and AA6082 was investigated in detail to understand the influence of the substrate in coating formation. The results imply that the formation mechanism strongly depends on alloying elements of the substrate. Conversion layer growth involves dissolution and deposition of ions. It was found that the alloying elements have a slowdown influence on aluminium dissolution. The results imply that high alloyed aluminium tends to form a coating with less thickness and lower Zr-Cr concentration.

The cobalt depleted layer of WC–Co composite materials was investigated after selective cobalt etching in diluted Caro’s acid. The time dependence of Co etching and the thickness of the etched layer was determined by using Glow Discharge Optical Emission Spectrometer (GD-OES) depth profiling as well as by calculation method based on determination of the dissolved Co by Atomic Absorption Spectrophotometric (AAS) measurement. The integrity of the modified outermost layer of the WC–Co composite materials were qualified using Rockwell C indentation test. This test methods were found usable for optimisation of the pre-treatment applied before the diamond thin film deposition.

Sophisticated metallographic techniques helped reveal numerous new features developed at the inner interfaces of the hot-dip aluminized C45 carbon steel specimens. Multi-intermetallic phases composing of Fe 2 Al 5 , Fe 4 Al 13 , FeAl 3 , and FeAl were identified whereby it was also found that the FeAl 3 phase did not inherent from Fe 2 Al 5 , rather it is the Fe 4 Al 13 phase that exists at the outermost layer of Fe 2 Al 5 toward the aluminum topcoat where the Fe 2 Al 5 layer has the most prominent grain size. In addition, the Gibbs free energies are consistent and underline the preferential growth of the Fe 2 Al 5 phase having ΔG° = − 197.6 kJ/mol at 700°C.

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