Zbigniew Konopka

Tests to produce a white cast iron die casting

Abstract

The manufacturing of cast iron castings by pressure die casting method, evaluation of castings microstructure and process analysis were the purpose of the experiments. White cast iron castings were fabricated and then these castings were annealed. The malleable cast iron castings were obtained this way. The capability of pressure die casting method for cast iron castings manufacturing was stated.

Keywords: white cast iron, die casting, heat treatment, malleable cast iron, microstructure,

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Natalia Sobczak, Jerzy J. Sobczak, Artur Kudyba, Marta Homa, Grzegorz Bruzda, Marcin Grobelny, Małgorzata Kalisz, Karlheinz Strobl, Riju Singhal, Mathieu Monville

Wetting transparency of graphene deposited on copper in contact with liquid tin

Abstract

Wetting behavior of liquid Sn (99.99%) on graphenecoated Cu substrate was investigated by the sessile drop method using two testing procedures: 1) classical contact heating (CH) of a couple of materials; 2) capillary purification (CP) allowing non-contact heating accompanied with squeezing the Sn droplet through a hole in an alumina capillary. The tests were performed in vacuum (p < 1.80 × 10-6 mbar) at 360 °C for 300 s. The images of Sn/substrate couples were recorded by high-resolution high-speed CCD camera. The results of this study evidenced that graphene layer is transparent for liquid Sn and after 300 s interaction, it forms the contact angles (θ) similar to those on pure Cu substrates, both in CH (θ = 59°) and CP (θ = 32°) tests. However, with liquid Sn, apparently the same effect of graphene wetting transparency is more complicated than that with water and it is caused by different mechanism, most probably, accompanied with reconstruction of the graphene layer.

Keywords: graphene, liquid tin, sessile drop, wetting transparency, liquophilic, liquophobic,

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Piotr Dudek, Aleksander Fajkiel, Tomasz Reguła, Edward Czekaj, Janusz Mielniczuk

The effect of the addition of circulating scrap on the tensile properties of die cast magnesium alloy

Abstract

Recycling of magnesium alloys is a complex issue not only because of their high reactivity and flammability even below melting temperature, but primarily because of a lack of equipment and experience in foundries. Nonetheless the environmental factors and the economic aspects of magnesium casting processes require the proper use of scrap. The problem relates not only to magnesium foundries but every foundry. However, due to the difficulty of melting and treating magnesium alloys there is a common belief that good mechanical properties can be achieved only by using pure ingots. The present research investigating the effect of process scrap on the mechanical properties of AZ91 and AM50 die cast parts. The results have shown that a particular content of the scrap causes an increase in the tensile strength and in elongation, which can have a profound effect on the applicability of the magnesium alloys. This article presents results of research on the optimum content of process scrap in the melt related to mechanical properties of AZ91 and AM50 die cast parts.

Keywords: magnesium alloys, metal charge, process scrap, pressure die casting, mechanical properties,

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Tomasz Dudziak

High temperature performance of materials for the energy sector exposed to water steam

Abstract

In this work, issues regarding the energy sector in Poland are described in terms of subcritical technology which is commonly used and plays the most important role in electric power production. In such technology steam temperature reaches 500-530°C with 14-16 MPa pressure. In addition, in this study the mechanism of high temperature corrosion of Fe and Ni- based materials with a different content of Cr considered for construction of new coal power plants will be discussed. The study clearly shows that at high temperatures (675°C and 725°C) in a pure steam atmosphere the Fe based alloy with 18 wt.% of Cr creates the formation of Fe-Cr spinel, the phase indicates poorer corrosion resistance than Cr2O3, however better than magnetite (Fe3O4) or hematite (Fe2O3). It was also shown that Fe based alloys were characterised by the development of islands rich in Fe3O4. The formation of such islands is related to an unequal distribution of iron concentration and its activity within the matrix, and the inability to create a thin protective layer of spinel or an independent layer of Cr2O3. The Ni based alloy 718+ developed a layer of Ni-Cr spinel (NiCr2O4) with a thickness of 2 μm.

Keywords: high temperature corrosion, power unit, Fe based alloys with Cr content, Ni based alloy,

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Władysław Madej, Irena Izdebska-Szanda, Janusz Miklaszewski, Tadeusz Zdończyk

The ecological and material-saving technology for producing brake blocks with stable parameters of quality Part 2. Verification of modernized technology under real conditions

Abstract

The presented article is the second in the series, which presents research related to the improvement of technology for producing brake blocks for the railway industry in the Spomel foundry in Lębork. The cooperation with the Foundry Research Institute started with the implementation of a project which modernised the process for producing casts of a new generation of non-sparking brake blocks for the needs of the railway industry in the years 2000-2001. Within the framework of this project an ecological and material-saving technology was developed for producing non-sparking brake blocks with high quality parameters. The research results obtained from the development of the technology are presented in the present article. The research included, among other things, the development of a method for feeding the cast, the selection of moulding and core sands which ensure improved dimensional accuracy and quality of surfaces of casts, stabilisation of technological parameters of produced casting moulds, the research of the structure, mechanical properties and abrasion of examined cast material, as well as determination of technological parameters for the casting process.

Keywords: brake block casts, improving the quality of the cast, moulding sand, reducing costs, saving energy and material, environmental protection, decreasing work arduousness,

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Krzysztof Jaśkowiec, Waldemar Uhl

Assessment of aluminium steel casting fluidity

Abstract

This text presents the methodology and results of testing aluminium steel casting fluidity obtained in the bar test. These results have been compared with the fluidity of chrome-nickel-copper steel casting tested under the same conditions. The course of performed fusions has also been presented. In addition to dilatometric testing also crystallisation and cooling recording has been performed with determination of the liquidus and solidus temperatures. Photographs of the resulting micro-structure of the tested steel castings are also presented.

Keywords: Fe-Al, fluidity, intermetallic phase base alloys, dross, bar test, crystallisation and cooling curve, dilatometric test,

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