This paper presents the results of studies on the consolidation of metallic and composite powders by the hot isostaticpressing (HIP) process intended for electrical contact materials. Ag, Cu metallic powders, as well as AgW48Re2, AgRe1 and CuW47Re3 composite powders were used in the investigations. Green compacts for consolidation and hot sintering under pressure were prepared by double-sided axial pressing in steel dies. The density, electrical conductivity, and hardness were measured on the obtained sinters after the HIP process, and the microstructure was examined on selected ones. The research indicates that applying this technology allows good quality electrical material to be obtained, intended for electrical contact material.
The article presents tests on a new lead-free bronze CuSn4Zn2PS, intended for fittings for contact with drinking water, in which the addition of lead was replaced with sulphur. The subject of the experimental work was the production of semi-finished products from this alloy based on the charge coming entirely from waste generated after machining. A specialized pilot line was used for the tests, and after cleaning, the waste was melted and then were continuously cast in the form of rods and hollow rods. The cleaning efficiency was assessed, and the manufactured semi-finished products were subjected to tests, including the assessment of the chemical and mechanical homogeneity and the structure of the test batch of the semi-finished casting products in terms of the possibility of manufacturing products meeting the requirements of technical specifications. The obtained results, both in terms of a stable chemical composition, homogeneous and reproducible mechanical properties, fully compliant with the specifications for fittings bronzes (CC499K), as well as the lack of faults of the obtained semi-finished products, despite a very large share of waste material, indicate the possibility of using the tested recycling method for the production of semi-products of sulphur bronze, which is an alloy that is relatively difficult to manufacture.
The paper presents the results of research aimed at developing assumptions for the preparation of a charge in the form of fine scrap copper alloys (chips/shells) guaranteeing effective removal of impurities and obtaining a metal bath of the required metallurgical quality. The tests were conducted for tin-zinc-lead bronze of the CC499K grade. As part of the work, the characteristics of this type of waste available on the market were made in terms of quality and the possibility of their use for the production of both alloys and finished products, taking into account the elimination of harmful impurities that may ultimately affect the production process adversely. The subject of the work was the selection of appropriate waste cleaning methods in the form of an oily shell in the CC499K (CuZn5Sn5Pb2) grade and its drying in terms of increasing the use of impure waste from machining as scrap for direct melting. The waste was assessed in relation to individual parameters. The research was carried out on 3 groups of waste, with varying degrees of moisture.
This paper presents the results of research concerning the evaluation of tribological properties of graphite materials used, among others, for crystallisers for continuous casting of non-ferrous metals and their alloys. Graphite materials differing not only in their physical properties but also in the technology of their production were selected from a wide range of commercially available products. Wear resistance investigations of the tested graphite materials were carried out on a pin-on-disc tribometer under technically dry friction conditions on a sliding distance of 1000 m. A constant load but variable speed was used in the tests. The mean value of the coefficient of friction and the wear of the material were determined based on the tribological tests carried out. It was observed that as the speed increases, the average value of the coefficient of friction decreases, while the wear increases. A microstructural analysis of the wear track showed that the friction mechanism depends mainly on the graphite formation technology, which is related to the microstructure of the tested materials, and to a lesser extent to their physical and mechanical properties. Varying the speed values made it possible to trace changes in the wear mechanism, on the basis of which it is possible to predict the durability and reliability of graphite crystalliser operation.