Metallographic and corrosion research of copper from archaeological sites

In this study, copper slabs - ingots, from both Gdańsk and Krakow were examined. Besides metallographic examinations, attention was focused on analyses of corrosion products. The following techniques were applied: scanning electron microscopy with fluorescent X-ray microanalysis and X-ray diffraction. The conducted investigations enabled determination of the causes of corrosion in the old copper slabs, due mainly to the mediaeval alloying techniques and copper processing technologies

Refining processes in the copper casting technology

The paper presents the analysis of technology of copper and alloyed copper destined for power engineering casts. The casts quality was assessed based on microstructure, chemical content analysis and strength properties tests. Characteristic deoxidising (Logas, Cup) and modifying (ODM2, Kupmod2) formulas were used for the copper where high electrical conductivity was required. Chosen examples of alloyed copper with varied Cr and Zr content were studied, and the optimal heat treatment parameters were tested for a chosen chromium copper content, based on the criterion of hardness and electrical conductivity tests. Searching for materials with high wear resistance, the influence of variable silicone content on the properties of CuNiSi alloy was researched

Scattering of Dirac particles from non-local separable potentials: the eigenchannel approach

An application of the new formulation of the eigenchannel method [R. Szmytkowski, Ann. Phys. (N.Y.) {\bf 311}, 503 (2004)] to quantum scattering of Dirac particles from non-local separable potentials is presented. Eigenchannel vectors, related directly to eigenchannels, are defined as eigenvectors of a certain weighted eigenvalue problem. Moreover, negative cotangents of eigenphase-shifts are introduced as eigenvalues of that spectral problem. Eigenchannel spinor as well as bispinor harmonics are expressed throughout the eigenchannel vectors. Finally, the expressions for the bispinor as well as matrix scattering amplitudes and total cross section are derived in terms of eigenchannels and eigenphase-shifts. An illustrative example is also provided.Comment: Revtex, 9 pages, 4 figures, published versio

Family involvement for children with disruptive behaviors: The role of parenting stress and motivational beliefs

Children with disruptive behaviors are at risk for adverse outcomes. Family involvement is a significant predictor of positive child behavior outcomes; however, little research has investigated parent psychological variables that influence family involvement for children with disruptive behaviors. This study investigated the role of parental motivational beliefs (i.e., role construction and efficacy) as a potential mechanism by which parenting stress impacts family involvement for families of children with disruptive behaviors. Results indicated that parent role construction mediated the relation between parenting stress and all aspects of family involvement examined (i.e., home-based involvement, school-based involvement, and home–school communication). Parent efficacy mediated the relation between parenting stress and home-based involvement only. Parents of children with disruptive behaviors reporting stress may experience negative beliefs about their role and efficacy to support their child’s education, which may thereby negatively influence their actual involvement. Therefore, parent motivational beliefs may serve as an important point for intervention to support involvement of families of children with disruptive behavior

Influence of refining treatments on the properties of Al-Si alloys

The article focused on researching the influence of Ti, B, Sr and Na as a modifying treatment elements for Al-Si alloys. The influence of alloying additives such as Cu and Cr was studied. Tensile strength Rm, elongation A5 and HB hardness was analysed, as well as the influence of the above-mentioned elements on the microstructure and solidification of alloys containing a varied content of Si, within the 7 ÷ 16 % range. The influence of heat treatment on the alloy properties was also researched

Copper alloys in investment casting technology

This paper presents research results in the field of casting technology of copper and copper alloys using the investment casting technology, both from historical as well as modern technology perspective. The analysis of exemplary elements of the old casting moulds is included, as well as the Bronze Age casts. The chemical content of various copper alloys was determined and the application of lost wax method was confirmed in the Bronze Age workshop. At present, investment casting method is used for manufacturing high-quality casts, especially products for power engineering that is why it demands respecting very rigorous technological requirements. The casts were characterised based on microstructure research, chemical composition and conductivity in relation to oxygen content