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Abstract

The exudation layer seriously affects the properties and the surface finish of the tin bronze alloy. The effective control of the exudation thickness is important measure for improving the properties of the alloy. In order to study the influence of process parameters on the thickness of exudate layer, the tin bronze alloy was prepared by continuous unidirectional solidification technology at different process parameters. The microstructure of the continuous unidirectional solidification tin bronze alloy was analyzed. The effect of process parameters on microstructure and chemical compositions was studied by orthogonal experiment. The results show that there exists an exudation layer on the surface of the continuous unidirectional solidification tin bronze alloy, and the exudation is mainly composed of a tin-rich precipitated phase. It indicates that the continuous casting speed is the main factor affecting the thickness of exudation layer, followed by mold temperature, melt temperature, cooling water temperature and cooling distance.
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Abstract

During excavation of the cremation cemetery of urnfield culture in Legnica at Spokojna Street (Lower Silesia, Poland), dated to 1100-700 BC, the largest - so far in Poland – a collection of casting moulds from the Bronze Age was discovered: three moulds for axes casting made out of stone and five moulds for casting sickles, razors, spearhead and chisels, made out of clay. This archaeological find constituted fittings of foundrymen’s graves. In order to perform the complete analysis of moulds in respect of their application in the Bronze Age casting technology analytical methods, as well as, computer aided methods of technological processes were used. Macroscopic investigations were performed and the X-ray fluorescence spectrometry method was used to analyse the chemical composition and metal elements content in mould cavities. Moulds were subjected to three-dimensional scanning and due to the reverse engineering the geometry of castings produced in these moulds were obtained. The gathered data was used to perform design and research works by means of the MAGMA5 software. Various variants of the pouring process and alloys solidification in these archaeological moulds were simulated. The obtained results were utilised in the interpretation of the Bronze Age casting production in stone and clay moulds, with regard to their quality and possibility of casting defects occurrence being the result of these moulds construction. The reverse engineering, modelling and computer simulation allowed the analysis of moulds and castings. Investigations of casting moulds together with their digitalisation and reconstruction of casting technology, confirm the high advancement degree of production processes in the Bronze Age.
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Abstract

Cast axes are one of the most numerous categories of bronze products from earlier phases of the Bronze Age found in Poland. They had multiple applications since they were not only used objects such as tools or weapons but also played the prestigious and cult roles. Investigations of the selected axes from the bronze products treasure of the Bronze Age, found in the territory of Poland, are presented in the hereby paper. The holder of these findings is the State Archaeological Museum in Warsaw. Metallurgical investigations of axes with bushing were performed in respect of the casting technology and quality of obtained castings. Macroscopic observations allowed to document the remains of the gating system and to assess the range and kind of casting defects. Light microscopy revealed the microstructure character of these relicts. The chemical composition was determined by means of the X-ray fluorescence method with energy dispersion (ED-XRF) and by the scanning electron microscopy with X-ray energy dispersion analysis in micro-areas (SEM-EDS). The shape and dimensions of cores, reproducing inner parts of axes were identified on the basis of the X-ray tomography images. Studies reconstructed production technology of the mould with gating system, determined chemical composition of the applied alloys and casting structures as well as revealed the casting defects being the result of construction and usage of moulds and cores.
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Abstract

High prices of tin and its limited resources, as well as several valuable properties characterising Cu-Sn alloys, cause searching for materials of similar or better properties at lower production costs. The influence of various nickel additions to CuSn10 casting bronze and to CuSn8 bronze of a decreased tin content was tested. Investigations comprised melting processes and casting of tin bronzes containing various nickel additions (up to 5%). The applied variable conditions of solidification and cooling of castings (metal and ceramic moulds) allowed to assess these alloys sensitivity in forming macro and microstructures. In order to determine the direction of changes in the analysed Cu-Sn-Ni alloys, the metallographic and strength tests were performed. In addition, the solidification character was analysed on the basis of the thermal analysis tests. The obtained results indicated the influence of nickel in the solidification and cooling ways of the analysed alloys (significantly increased temperatures of the solidification beginning along with increased nickel fractions in Cu-Sn alloys) as well as in the microstructure pattern (clearly visible grain size changes). The hardness and tensile strength values were also changed. It was found, that decreasing of the tin content in the analysed bronzes to which approximately 3% of nickel was added, was possible, while maintaining the same ultimate tensile strength (UTS) and hardness (HB) and improved plasticity (A5).
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