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Stabilisation of mechanical properties in silver alloys by addition of lanthanidesPurpose: Silver alloys intended for industrial application should characterise by high electrical conductivity (as pure silver) as well as high mechanical and functional properties, stable also at elevated temperature. The objective of this work was to investigate the mechanical properties stability of Ag-La (0.5%) and Ag-mishmetal (1 and 4%) alloys caused by severe plastic deformation compared to the Ag+(7.5 wt %)Cu alloy and pure Ag materials.Design/methodology/approach: Tests were made with the samples obtained by casting and further plastic working included KOBO® extrusion process and drawing. Wires were annealed in temperature range 50 - 500°C. The mechanical properties (at room temperature, elevated temperature and after annealing) and microstructure were examined. The values of yield strength obtained in a tension tests have been compared to the values calculated theoretically.Findings: Additive of rare earth metals contributed to fine structure obtaining, particles formed in grain boundaries stabilized microstructure at elevated temperature. Increase of mechanical properties of investigated alloys was connected with presence of fine precipitations in silver matrix, which confirmed susceptibility to precipitation hardening of silver – mishmetal alloys.Research limitations/implications: Ability of new alloys to precipitation hardening should be confirmed by further investigations, including solution heat treatment and ageing, also for materials prepared in vacuum furnace.Practical implications: Stability of mechanical properties at elevated temperature, gives possibility to use of new silver allays for producing elements designed to operate at elevated temperatures or exposed to rapid temperature changes. Increased mechanical properties and good tarnish resistance indicates possibility of new applications of investigated alloys in jewellery and medicine, after additional and essential investigations.Originality/value: The wire made from this material could be easily produced by the developed processing methods, without the need to use annealing operations.
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Dilatometric examination of moulds with plaster binderInvestigations concerning thermal expansion of moulding materials with plaster binder have been performed for two mixture compositionsof Authors’ own design, as well as for the material used in jewellery industry under the Prima-Cast trade name, and for ThermoMold 1200moulding material. The results of dilatometric examinations of these materials, carried out within the temperature range from about 20°Cto 650°C by means of the DA-3 automatic dilatometer, have been compared. An analysis of this comparison has revealed that it is thematrix composition which is decisive for the magnitude of dimensional changes of moulds, and that applying components which do notexhibit polymorphic transformations reduces dimensional changes of a mould during its thermal treatment.
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Teaching the plating of surface layers using an E-learning platformPurpose: The aim of this paper is to present the role of e-learning tools in the process of students teaching withinthe area of material science, on the base of an e-platform for teaching students the processes of surface layers plating.Nowadays classical teaching tools are replaced with computer tools presenting analyzed processes and structures in avirtual space so the purpose of the work is also to present a form of comparison of these approaches.Design/methodology/approach: The presented results base on the elaboration and investigations of thee-learning program for Polish students helping them to understand the process of surface layers plating. The program hasbeen checked according specific educational requirements of the educational process of a technological university.Findings: Results obtained in the work point the importance of application of an e-learning platform in aneducational process of the material science students. Also the methodology of creating such e-learning platformsand their educational estimation are presented.Research limitations/implications: The main limitation is related with the analyzed manufacturing process:surface layers plating. Moreover the subject has been limited to the group of main galvanic layers, as this work is a resultof investigations in the area of galvanic layers electroplating. Secondly the project takes into account only the layers thatare the most characteristic and are the most spread in the industry for the described electroplating technique.Practical implications: The first practical implication of these researches is the possibility for offering a widerscope of materials on the educational platforms prepared for the new university e-learning system. Secondly,it is possible to use these materials in consultations offered for industrial plants in the system of commercialcooperation of the university.Originality/value: The work presents the original e-learning program for teaching the students of materialscience. In the process of preparing the program some interesting solutions consider with visualization techniqueshave been done.