PVD hard coating of steels is a well-known surface technology for significantly improving friction and wear behavior. In principle, hard coating can also be carried out on cast irons and Al alloys, but due to the insufficient load-supporting capacity of the soft base materials, i.e. of the microstructural constituents, this technology is inapplicable for wear protection of cast iron and Al alloys.

This paper deals with research activities into using electron beam (EB) liquid-phase surface treatments both without additives (remelting) and with additives (alloying) to improve the conditions for the deposition of thin PVD hard coatings on these different groups of materials.

The EB remelting of cast irons is already used for wear protection on an industrial scale. The ledeburitic microstructure of the remelted layer led to increased hardness up to a value of 700 HV0.1. Moreover, EB alloying using Ni-based additives allows the generation of a broad range of different microstructures, with hardness values ranging from 400 to 900 HV0.1. The specific layer thickness (0.3 to 1 mm) depended on the energy input. The graphite was eliminated in the layer transformed by the EB, and complete coverage with PVD coatings could be achieved.

In the case of Al alloys, the EB alloying was carried out using Co-based additives. The hardness of the layers could be increased up to 400 HV0.1, with thicknesses between 0.5 and 1.0 mm.

Comparative studies of single (PVD hard coating of base materials) and duplex technologies (EB surface treatment with subsequent PVD hard coating) were carried out. The different load capacities resulting from the surface treatments were investigated, and the hardness, friction behavior, and wear behavior (ball-on-flat test) were measured. Apart from the influence of the EB layer configurations, the effect of different PVD coatings (TiN, TiAlN, TiCN) was taken into consideration.

Special attention was focused on the influence of the temperature-time cycles during the subsequent PVD hard coating on the different material-specific microstructures and hardness values of the EB-treated layers.

In addition, the research activities were focused on specific aspects and effects of the chemical composition directly at the material surface on the formation, roughness, and adhesion of the PVD coatings, especially in the case of the Al alloys. For this purpose, XPS analyses and scratch tests under increased loading conditions were performed.

Galling, the transfer of workpiece material to tool surfaces, is an important factor known to influence both wear behaviour and loading conditions of metalworking tools such as deep-drawing, blanking or fine blanking punches or dies.

In the current study, the states of a range of technically rough surfaces coated by AlCrN-based thin films using rotating cathodes arc evaporation PVD were characterized with regard to their galling behaviour. Furthermore, the influence of common post-treatment methods such as blasting or polishing on the early stages of galling of mild steel on coated surfaces was investigated in detail.

Repeated dry-sliding contact, such as tool surfaces do encounter during operation, was physically simulated by a carefully selected ball-on-disc test setup with an applied contact pressure resembling the conditions between a steel sheet and the lateral surface of a fine blanking punch.

The initial stages of galling were investigated by comparison of the development of the friction coefficient and the morphology of early iron adhesions to a range of differently post-treated coating surfaces. Depending on the surface roughness influenced by the applied post treatment method, hard coatings show a distinctively different galling behaviour in unlubricated contact conditions.

The improvement of the gas barrier properties of polypropylene (PP), one of the most frequently used materials in the packaging industry, has been greatly demanded to extend the shelf life of the packaging goods by preventing the rapid degradation of the contents. In this work, the gas barrier property of PP was significantly improved by a factor of 15 through the plasma treatment of gamma-aminopropyltrimethoxysilane (γ-APS), as compared with that of non-treated PP. It was also suggested that the γ-APS was effectively converted into crosslinked SiO_x with high gas barrier characteristics after 60 s plasma treatment.

After the corrosion tests, the surface of the borided and non-borided steels were analyzed by scanning electron microscopy (SEM), Energy Dispersive X-Ray Spectrometry (EDS) and X-Ray Photoelectron Spectroscopy (XPS) techniques to determine the corrosion mechanisms, the presence of the chemical elements on the surface of the borided and non borided steels, and the quantitative chemical composition of the specimens developed on the surface during the 10 days of exposition in the Hank’s solution.

Based in the Nyquist plots estimated from the corrosion tests over the surface of borided and non-borided steels immersed in Hank’s solution during 10 days of exposure, the borided steel provided a reasonable corrosion resistance of approximately 45 KWcm², while the corrosion resistance of the AISI 316 steel reached a maximum polarization resistance of 2138 KWcm².

In addition, according to the SEM and EDS results, pitting and crevice corrosion mechanisms were observed on the surface of the non-borided and borided steels respectively, whereas the phosphorus (or phosphates) content over the surface of borided steel increased as a function of the exposure time, and can be related by its low corrosion resistance compared with the values estimated in AISI 316 steel.

Finally, equivalent electric circuits (EEC’s) were proposed for the analysis of the resulting impedance data for both borided and non-borided steels immersed in the simulated body fluid during 10 days of exposure.