The aim of the paper is to formulate physically well founded yield condition for initially anisotropic solids revealing the asymmetry of elastic range. The initial anisotropy occurs in material primarily due to thermo-mechanical pre-processing and plastic deformation during the manufacturing processes. Therefore, materials in the “as-received” state become usually anisotropic. After short account of the known limit criteria for anisotropic solids and discussion of mathematical preliminaries the energy-based criterion for orthotropic materials was formulated and confronted with experimental data and numerical predictions of other theories. Finally, possible simplifications are discussed and certain model of isotropic material with yield condition accounting for a correction of shear strength due to initial anisotropy is presented. The experimental verification is provided and the comparison with existing approach based on the transformed-tensor method is discussed.
The aim of this paper was to test currently available on the market products for sealing anodic oxide coatings as well as to test the use of other alternative substances improving the sealing process. The ability to seal in 10 different solutions and the quality of the seal has been tested. The influence of the applied preparations on corrosion resistance and resistance to strongly alkaline environment was also investigated.
Based on the results obtained, satisfactory results were archived for the sample sealed in a IMN-OML (Institute of Non-Ferrous Metals in Gliwice, Light Metals Division) solution sealant and in solution of nickel acetate in a medium-temperature process. Sealing by means of nickel acetate solutions is economically justified, and its use allows the process temperature to be lowered. When it comes to resistance to alkalis, samples sealed in IMN-OML sealant are the best. Commercial solutions have also achieved positive results in all tests.
In this article the structural and mechanical properties of grain refinement of Cu-Sn alloys with tin content of 10%, 15% and 20% using the KOBO method have been presented. The direct extrusion by KOBO (name from the combination of the first two letters of the names of its inventors – A. Korbel and W. Bochniak) method employs, during the course of the whole process, a phenomenon of permanent change of strain travel, realized by a periodical, two-sided, plastic metal torsion. Moreover the aim of this work was to study corrosion resistance. The microstructure investigations were performed using an optical microscope Olimpus GX71, a scanning electron microscope (SEM) and a scanning transmission electron microscope (STEM). The mechanical properties were determined with INSTRON 4505/5500 machine. Corrosion tests were performed using «Autolab» set – potentiostat/galvanostat from EcoChemie B.V. with GPES software ver. 4.9. The obtained results showed possibility of KOBO deformation of Cu-Sn casting alloys. KOBO processing contributed to the refinement of grains and improved mechanical properties of the alloys. The addition of tin significantly improved the hardness. Meanwhile, with the increase of tin content the tensile strength and yield strength of alloys decrease gradually. Ductility is controlled by eutectoid composition and especially δ phase, because they initiate nucleation of void at the particle/matrix interface. No significant differences in the corrosion resistance between cast and KOBO processed materials were found.
The paper presents the results of the electrodeposition of nickel composite coatings reinforced with the ceramic SiC particles. A Watts type galvanic bath modified with various organic additives was used. These additives were: 2-sulfobenzoic acid imide (LSA), dioctyl sulfosuccinate sodium salt (DSS), sodium dodecyl sulfate (SDS), tris (hydroxymethyl) aminomethane (THAM) and hexamethyldisilizane (HMDS). The nickel composite coating was electrodeposited on a 2xxx aluminum alloy series substrate (EN-AW 2017) with zinc interlayer. Studies concerned the effect of the applied organic additives on properties of composite coatings such as: microstructure, microhardness, adhesion to the substrate, corrosion resistance and roughness. The structure of the coatings was assessed by scanning electron microscopy and light microscopy. Based on the studies of zeta potential it was found that the bath modification had a significant impact on the amount of the ceramic phase embedded in metal matrix. The tests conducted in a model 0.01 M KCl solution were not fully representative of the true behavior of particles in a Watts bath.
The paper presents the results of the electrodeposition of nickel composite coatings reinforced with the nano size SiC ceramic particles. The type and size of the ceramic particles or organic additives used play a important role during electrodeposition processes. A Watts type galvanic bath with various organic additives was used. These additives were: 2-sulfobenzoic acid imide, dioctyl sulfosuccinate sodium salt (DSS), sodium dodecyl sulfate, tris (hydroxymethyl) aminomethane and hexamethyldisilizane. The nickel composite coating was electrodeposited on a 2xxx aluminum alloy series substrate (EN-AW 2017) with zinc interlayer. The work concerns the determination of the impact of the change in the zeta potential of SiC nanoceramic particles used on properties of composite coatings (wear resistance, corrosion, etc.). The paper characterized the composite nickel coatings on aluminum alloy using SEM techniques, wear resistance tests by TABER method and coating adhesion to the substrate using the “scratch test” method. The corrosion resistance of coatings was also tested using electrochemical methods. The research allowed to determine the effect of SiC nanoceramic particle size on the value of the zeta potential in the model KCl solution.
This study characterizes the bronze jewellery recovered from the Lusatian culture urn-field in Mała Kępa (Chełmno land, Poland). Among
many common ornaments (e.g. necklaces, rings, pins) the ones giving evidence of a steppe-styled inspiration (nail earrings) were also
identified. With the dendritic microstructures revealed, the nail earrings prove the implementing of a lost-wax casting method, whereas
some of the castings were further subjected to metalworking. The elemental composition indicates the application of two main types of
bronze alloys: Cu-Sn and Cu-Sn-Pb. It has been established that the Lusatian metalworkers were familiar with re-melting the scrap bronze
and made themselves capable of roasting the sulphide-rich ores.
The collection from Mała Kępa has been described in terms of its structure and composition. The investigations were made by means of
the energy dispersive X-ray fluorescence spectroscopy (ED-XRF), scanning electron microscopy (SEM) coupled with an energy dispersive
X - ray analysis system (EDS) and optical microscopy (OM). In order to fingerprint an alloy profile of the castings with a special emphasis
on the nail earrings, the data-set (ED-XRF, EDS) was statistically evaluated using multidimensional analyses (FA, DA).