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Interaction of Titanium with Ceramic Molds in the Conditions of Electron Beam Casting Technology

Kaliuzhnyi P., Voron M., Mykhanian O., Tymoshenko A., Neima O., Iangol O.

Archives of Foundry Engineering

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2021

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Vol. 21, iss. 3

27--32

EN

For the manufacture of near net shape complex titanium products, it is necessary to use investment casting process. Melting of titanium is promising to carry out by electron beam casting technology, which allows for specific processing of the melt, and accordingly control the structure and properties of castings of titanium alloys. However, the casting of titanium in ceramic molds is usually accompanied by a reaction of the melt with the mold. In this regard, the aim of the work was to study the interaction of titanium melt with ceramics of shell molds in the conditions of electron beam casting technology. Ceramic molds were made by using the following refractory materials – fused corundum Al2O3, zircon ZrSiO4 and yttria-stabilized zirconium oxide ZrO2, and ethyl silicate as a binder. Melting and casting of CP titanium was performed in an electron beam foundry. Samples were made from the obtained castings and electron microscopic metallography was performed. The presence and morphology of the altered structure, on the sample surface, were evaluated and the degree and nature of their interaction were determined. It was found that the molds with face layers of zirconium oxide (Z1) and zircon (ZS1) and backup layers of corundum showed the smallest interaction with the titanium melt. Corundum interacts with titanium to form a non-continuous reaction layer with thickness of 400-500 μm. For shell molds with face and backup layers of zircon on the surface of the castings, a reaction layer with thickness of 500-600 μm is formed. In addition, zirconium-silicon eutectic was detected in these layers.

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Novel Method of Thermal Conductivity Measurement Using Stefan-Boltzmann Law

Leśniewski W., Czekaj E., Wieliczko P., Wawrylak M.

Archives of Metallurgy and Materials

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2019

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Vol. 64, iss. 1

311--315

EN

The article presents a novel method that allows measurement of thermal conductivity that is based on Stefan-Boltzmann law. The developed method can be used to determine thermal conductivity of ceramic investment casting molds. The methodology for conducting thermal conductivity tests of ceramic material samples is presented. Knowledge of the value of thermal capacity and thermal conductivity as a function of temperature enables computer simulations of the process of cooling and solidification of liquid metal in a mold.

3

Badania właściwości mas formierskich z korundu i glinokrzemianu przeznaczonych na ceramiczne formy odlewnicze

Wiśniewski P., Sitek R., Mizera J.

Szkło i Ceramika

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2017

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R. 68, nr 6

16--20

PL

W artykule przedstawiono wyniki badań właściwości mieszanek formierskich z korundu oraz glinokrzemianu (Remasil 60), które przeznaczono na pierwszą warstwę oraz warstwy konstrukcyjne form odlewniczych służących do odlewania precyzyjnego. Określono wpływ zawartości fazy stałej na parametry mas formierskich oraz dokonano wyboru systemów formierskich o odpowiednich parametrach. Najkorzystniejsze wyniki otrzymano dla mieszanek formierskich: przeznaczonych na warstwę przymodelową, których stężenie fazy stałej wynosiło 72,5% wag. oraz mieszanki na warstwy konstrukcyjne, gdzie udział proszku wyniósł 70% wag. Spoiwem konstrukcyjnym był nanokompozyt polimerowo-ceramiczny zawierający nanocząstki SiO2 (LUDOX AM30). Proszki charakteryzowano z użyciem: analizatora wielkości cząstek metodą dyfrakcji laserowej oraz skaningowych mikroskopów elektronowych (SEM), a nanokompozyt z wykorzystaniem mikroskopu STEM. Masy formierskie charakteryzowano pod względem: lepkości dynamicznej i względnej, gęstości, pH oraz adhezji do płyty (tzw. „test płyty”). Pomiary te przeprowadzano przez siedem dni w warunkach laboratoryjnych w temperaturze 20°C. Otrzymane wyniki pokazały, że masy lejne z korundu i glinokrzemianu oraz nanokompozytu zawierającego krzemionkę koloidalną charakteryzują się dobrymi właściwościami i mają szansę zostać zastosowane w odlewnictwie precyzyjnym do otrzymywania form.

EN

The paper presents results properties of alumina and aluminosilicate slurries dedicated to the first layer and construction layers of shell molds, respectively. The influence of the solid phase content on the parameters of the slurries was determined. Particle size distribution was determined with use of the advanced laser particle size analyzer Horiba LA-950 (LALLS technique). To characterize morphology of the powders and binder scanning electron microscopy (SEM and STEM) observations were performed. The slurries were prepared in a mechanical mixer. The experiment was based on a daily plate weight tests and pH, Zahn cup (4 mm diameter) viscosity and dynamic viscosity by rheometer with a shear rate range of 1–100–1 1/s measurements that are fundamental for investment casting industry. Adhesion of the examined mass was determined by the plate immersion (dimensions: 75×75 mm) in a slurry and estimation its weight of 75.46 g. The slurry dipping was controlled during 180 seconds with results notation every 15 seconds. The obtained results proved opportunity of their application for the investment casting and foundry, being prospective issue for future fabrication of shell moulds.

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Influence of Wax Pattern Surface Quality on Prime Coat of Ceramic Mold

Bałkowiec A., Wawulska P., Matysiak H., Rabajczyk A., Smektała P., Zdunek J., Kurzydłowski K.

Archives of Foundry Engineering

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2014

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Vol. 14, iss. 1 spec.

67--72

EN

The authors have made an attempt to enrich the knowledge about the influence of wax pattern washing process and its influence on the quality of the shell prime coat. Two types of wax were investigated: A7Fr/60 and KC2690. A7Fr60 is used for pattern fabrication, while KC2690 is typical sprue wax. The goal of work was to establish wax solubility accuracy in Trisol 60 Plus and Houghto Clean 530 versus time and influence of dipping time to wax samples surface quality. Additionally, after exposition of wax samples, their surface morphology was characterized with the use of laser profilometry and surface roughness measurement. The quality of formed prime coat was established by X-ray tomography. The measurement of wetting angle of the wax by binder was conducted. The results have shown that the main factor which influences the quality of the prime coat is surface wettability rather than wax surface roughness.