Preface

Abstract: The rapid progress in engineering enhances the demands set on materials requiring better mechanical properties, resistance to frictional wear, corrosion and erosion etc. These demands can be also satisfied by e.g. applying various surface engineering techniques which permit modifying the microstructure, phase and chemical composition of the surface layers produced on the treated parts. A prospective line of the development is the production of the intermetallic layers by combining various methods aimed to improve essentially the performance properties and service life of the treated parts. The paper presents properties of the Al2O3+TiAl3+TiAl+Ti3Al type layer produced on titanium alloy Ti6Al2Cr2Mo by duplex method combined with magnetron sputtering process of aluminium coating with a glow discharge assisted treatment. The results of the examinations: microstructure, chemical and phase composition, frictional wear resistance and mechanical properties are discussed. Produced composite surface layers have the diffusion character and a precisely specified structure, chemical and phase composition and good wear and corrosion resistance what can widen significantly application range of treated parts.

Abstract: For the improvement of a surface wear resistance of aluminum alloys, iron-based alloys were clad on the surface of an aluminum alloy by laser. By investigating the effect of CO2 and diode laser irradiation conditions on the formability of Fe-Cr-C clad layers, it was confirmed that the application of diode laser made it possible to obtain stable beads in low heat input compared with CO2 laser, which has been conventionally used for laser cladding. Besides, by optimizing the laser parameters, the dilution ratio of clad layers by Al substrate was minimized less than 10%. At the clad interface, the reaction layer consisting of Fe2Al5 and FeAl3 formed which caused cracks at the clad interface. Even by controlling laser conditions, this brittle layer formation could not suppressed. In this research, by using the immiscible Fe-Cu-Cr alloys as clad materials, Fe based clad layers were formed on Al substrate without any cracks at clad interface. By the effect of Marangoni motion of decomposed duplex liquid phases, Cu segregated between Al substrate and Fe based clad layers and suppressed the reaction between them.

Abstract: The paper presents the results of investigations into the structure and properties of Ni-Al diffusion layers produced on INCONEL 100 by Chemical Vapour Deposition (CVD). The process was carried out in aluminium chloride (AlCl3) mixed with hydrogen atmosphere. The as-deposited layers were subjected to thermal treatment in vacuum to optimize their adhesion, hardness and temperature-resistance. Microstructural characterization of the coatings was carried out by scanning electron microscopy (SEM) The chemical composition was measured via EDS and the phase content was investigated by X-ray diffraction XRD. The resistance to high temperature of the coatings at atmospheric pressure was tested by applying 24-hours cycles at 950 °C. Scratch-tests provided data on the microhardness and adhesion of the coatings. The results indicate that the layers produced on the INCONEL 100 exhibit a very good adhesion combined with exceptional corrosion resistance at high temperatures.

Abstract: It is commonly believed that the white layer formed during hard machining of steels is caused primarily by a thermally induced phase transformation resulting from rapid heating and quenching. The focus of this study is to investigate the white layers produced on the machined surfaces and on the inner side part of the chips in dry hard turning GCr15 with PCBN tools. Samples of machined workpiece and chips were metallographically processed and observed under a microscope to determine whether white layers were present or not. Some properties of white layers were deduced in order to verify some of the prevalent theories. More specifically, chip shapes were studied to determine how they developed during machining with potential appearance of white layers, with a view to correlating the chip shapes with the white layer formation.

Abstract: This paper presents investigation of surface layers. The diffusion layers were produced by using different parameters of reactive atmosphere (N2:H2). The research of the surface layers was performed using scanning electron microscope (SEM). The results of energy dispersive X-ray (EDX) analysis and X-ray diffraction (XRD) analysis are presented. Research reveals the influence of chemical constitution of reactive atmosphere on the change of properties of nitrided layers.