Materials Science Forum Vol. 782

Abstract: Commercially pure aluminium powder and a mixture of aluminium and silicon powders, both in a liquid amyl acetate-based organic binder, were sprayed onto the surface of Inconel 713LC nickel base superalloy. A two-stage heat treatment process in an argon atmosphere flow was designed and applied to produce nickel aluminide diffusion coatings. Two coating systems composed of different layers with gradual changes in chemical composition and phase quantities were formed. Scanning electron microscope, scanning electron microscope/focused ion beam, both equipped with energy dispersive microanalyzers, were utilized to characterize the microstructure and chemical composition of the coatings.

Abstract: The slurry aluminide coatings are produced on the three kind of substrates: hightemperature creep resistant cast steel, titanium alloy and nickel alloy. The slurry as active mixture containing aluminium and silicon powders, an activator and an inorganic binder. The coating were obtained by annealed in air atmosphere. The structure of these coatings is two zonal and depend on the type of substrate and technological parameters of producing.

Abstract: Nickel superalloy was coated by aluminide coatings by the slurry method. The slurry as active mixture containing aluminium and silicon powders, an activator and a binder. The coating were obtained by annealed in argon atmosphere. The structure of these coatings is two zonal and depends on time and temperature of producing. The phase composition was determined using following techniques: scanning electron microscopy (SEM) equipped with Xray microanalysis (EDS) combined with electron backscatter diffraction (EBSD) and Xray diffraction (XRD).

Abstract: The paper deals with nickel – cobalt coatings on the copper substrate prepared by electroplating process. The different Co content in the alloy coating depending on chemical composition of sulphate electrolyte and current density. The microstructure and composition of Ni-Co coating were observed with use of light and scanning electron microscopy. The mechanical properties were determined with use of the test according to EN ISO 6892-1:2009 standard and means of a Vickers microhardness tester. The results showed that under the same bath composition and technological parameters of process the Ni-Co alloy coating exhibited laminated structure. Their strength and hardness of the deposited coatings were higher than those for the Ni coatings.

Abstract: This paper is focused to structure characterization of two differently electrodeposited Ni-Co alloys on the copper surface. The chemical composition of the layers was determined by the EDX analysis in the scanning electron microscope. Phase analysis was realized by diffraction in the transmission mode using synchrotron radiation. Diffraction patterns also show the preferred orientation in the coating with saccharine addition.

Abstract: Magnetic nanoparticles used in biomedicine have to be biocompatible what can be achieved by the modification of the magnetic particle surface with an appropriate biocompatible substance. In the work protein bovine serum albumin (BSA) was chosen to modify the surface of magnetite nanoparticles. BSA coated magnetite nanoparticles (MFBSA) with different feed weight ratios of BSA to the magnetite Fe₃O₄ were prepared and thermally characterized using thermogravimetric analysis.

Abstract: Magnetic nanoparticles used in biomedicine require surface modification ensuring formation of non-toxic, biocompatible nanoparticles. Among the great variety of available biocompatible polymers, a hydrophilic polymer polyethylene glycol (PEG) that has the ability to prevent protein adsorption was chosen for coating prepared magnetite nanoparticles. The aim of this work was to use differential scanning calorimetry (DSC) for studying the adsorption of PEG of different average molecular weights and different feed weights on magnetite nanoparticles and to estimate the maximal amount of PEG adsorbed on the magnetite nanoparticles. The increasing PEG molecular weight has a tendency to the decrease in the maximal feed weight ratio of PEG to magnetite in the studied complex systems. The morphology observed by scanning electron microscopy showed that all studied systems of magnetic particles coated with PEG had almost spherical shape.

Abstract: Hard anodized layers were produced by two different manufacturers on the same type of aluminium alloy on a vacuum pump part of complex shape. The sulphuric acid/water solution was used to produce alumina layers, which were subsequently sealed in demineralized water. A comparative analysis based on metallographic methodology, with the aim to control the stability of alumina formation process and to identify its defects, was performed by means of light and scanning electron microscopy, surface profilometry and microhardness measurements. To determine the thickness of alumina layers, the image analysis was also used.

Abstract: Along with technologies development rise demands on the technical level of new machinery and equipment and also the reliability and efficiency of tools used in the production processes. One of the options for increasing tool life and wear resistance is the use of tools surface treatment technology called as CVD (chemical vapor deposition) and PVD (Physical Vapor Deposition) process. Chemical vapor deposition is a widely used materials-processing. CVD is an atomistic surface modification process, where a thin solid coating is deposited on an underlying heated substrate via a chemical reaction from the vapor or gas phase, PVD process is atomistic deposition process in which material is vaporized from a solid or liquid source in the form of atoms or molecules, transported in the form of a vapor through a vacuum or low pressure gaseous (or plasma) environment to the substrate where it condenses. The paper introduces the possibilities of application of these processes for cold forming tools used at operating conditions of Železiarne Podbrezová, a.s. Tools (formers and straightening rolls) are evaluated in terms of CVD and PVD coating thickness, microstructure and microhardness of tool material and coating.

Abstract: In the paper mutual comparison of zinc coatings enriched with small additions of Mg and Al (up to 1 wt.% Mg and 1 wt.% Al) and traditional zinc coatings produced by hot dip galvanizing, concerning some important properties of coatings like coating structure, cracks formation after deformation and corrosion resistance of deformed samples was studied. It was shown, that while traditional hot-dip zinc coatings are formed by homogenous zinc layer, exhibiting only low amount of soluble aluminium, coatings enriched by small amounts of Mg and Al, namely 0.6% Mg and 0.8% Al are formed by dendritic zinc matrix and interdendritic phase containing Zn-Mg-Al eutectics. Development of cracks was investigated in the area of maximal deformation of the samples subjected to stretching. It was found, that while traditional zinc coatings showed sporadic long fine cracks, zinc coatings enriched with Mg and Al exhibited aggregation of short thick cracks in the deformed area. Samples of both materials after stretching were also exposed in neutral salt spray atmosphere in corrosion chamber. It can be concluded, that material with coatings enriched with Mg and Al showed better results in corrosion tests contrary to the presence of massive cracks in the coating. This significantly increased corrosion resistance is possible due to excellent adhesion of zinc coatings, containing Mg and Al on drawing steels.