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A. Karwiński and Z. Żółkiewicz

Abstract

In the evaporative pattern casting process, the surface of a polystyrene pattern (Styrofoam) is coated with a ceramic layer. This ceramic layer, which coats the evaporative pattern, should have specific physiochemical properties including: resistance to thermal, chemical, and erosive activity of molten metal and proper permeability for gases which are produced by the evaporative polystyrene pattern. The article presents the research results of properties of experimentally selected ceramic layers applied on a polystyrene pattern in the evaporative pattern casting process.

Open access

A. Karwiński, M. Małysza, A. Tchórz, A. Gil and B. Lipowska

Abstract

Filtration of liquid casting alloys is used in casting technologies for long time. The large quantity of available casting filters allows using them depending on casting technology, dimensions of casting and used alloys. Technological progress of material science allows of using new materials in production of ceramic filters. In this article the Computed Tomography (CT) technique was use in order to evaluate the thickness of branch in cross section of 20ppi ceramic-carbon bonded foam filter. Than the 3D image of foam filter was used in computer simulation of flow of liquid metal thru the running system.

Open access

A. Karwiński, M. Małysza, P. Wieliczko, A. Gil and B. Lipowska

Abstract

Extremely intense development of civilization requires from foundry casting technologies very high quality and not expensive castings. In the foundries, there are many treatments that allow increasing of the final properties of produced castings such as refining, modification, heat treatment, etc. One of the methods of increasing the quality of the casting by removing inclusions from the liquid alloy is filtration. The use of ceramic-carbon foam filters in filtration process is still analysed phenomenon that allows improving the final properties of castings. A modern method of research, testing and synthesis of innovative chemical compositions allows improving the properties of such filters. In the paper the evaluation of application properties of developed ceramic-carbon bonded foam filters is presented. The quality of the foam filters is evaluated by Computer Tomography and foundry trials in pouring of liquid metal in test molds. Additionally computer simulations were made to visualize the flow characteristics in the foam filter. The analysed filters are the result of the research work of Foundry Research Institute and the Institute of Ceramics and Building Materials, Refractory Materials Department in Gliwice.

Open access

A. Karwiński, W. Lesniewski, P. Wieliczko and M. Małysza

Abstract

This paper discusses technical problems related with casting of titanium alloys in centrifugal vacuum furnaces. The potentials of an analysis of the centrifugal casting process carried out in the Flow3D software CFD (Computational Fluid Dynamics) were presented. Simulations were carried out on a model set, which enables casting of two connecting rods for an I.C. engine. Changes in the mould filling process were examined for the three selected spinning velocities of the casting arm. The ranges of the metal flow velocity in mould were calculated as well as metal pressure in mould after reaching a predetermined spinning velocity. The results and the adopted mould geometry enabled determination of the magnitude of stress occurring in mould at the time of filling it with liquid titanium alloy. The paper presents a methodology for testing of the ceramic material strength using a four-point loading arrangement. The strength of the ceramic material was determined on samples heated at different temperatures. The obtained results enabled a thesis to be formulated that for pouring of moulds in a centrifugal vacuum furnace, the layered foundry ceramic moulds can be safely used, and the use of moulds that will provide the directional solidification of metal should be possible as well.

Open access

A. Karwiński, R. Haratym and R. Biernacki

Abstract

The paper presents the effect of suction pressure exerted on the liquid AlSi alloy when it is introduced into a ceramic mould made in the investment process and the results compared with data obtained on gravity poured castings. The study used special pattern sets and ceramic moulds made with the alternately applied soluble silicate binder and ethyl silicate. Additionally, self-supported moulds based entirely on the Ekosil binder were used. In the analysis of castings, the following parameters were examined: a linear dimensional accuracy, the state of surface microgeometry and the possibility of metal penetration into a complex ceramic mould, allowing also for the presence of capillary phenomena. In the process of casting with back-pressure, the pressure values of 500 hPa, 600 hPa and 700 hPa were applied in the chamber where the ceramic mould was located, with the temperature of the said mould kept at a level of 150 ± 10°C.

Open access

A. Karwiński, R. Haratym, R. Biernacki and A. Soroczyński

Abstract

The article presents an analysis of the applicability of the Replicast CS process as an alternative to the investment casting process, considered in terms of the dimensional accuracy of castings. Ceramic shell moulds were based on the Ekosil binder and a wide range of ceramic materials, such as crystalline quartz, fused silica, aluminosilicates and zirconium silicate. The linear dimensions were measured with a Zeiss UMC 550 machine that allowed reducing to minimum the measurement uncertainty

Open access

B. Lipowska, J. Witek, T. Wala, A. Karwiński, P. Wieliczko, M. Asłanowicz and A. Ościłowski

Abstract

Trials of cast steel filtration using two types of newly-developed foam filters in which carbon was the phase binding ceramic particles have been conducted. In one of the filters the source of carbon was flake graphite and coal-tar pitch, while in the other one graphite was replaced by a cheaper carbon precursor. The newly-developed filters are fired at 1000°C, i.e. at a much lower temperature than the currently applied ZrO2-based filters. During filtration trials the filters were subjected to the attack of a flowing metal stream having a temperature of 1650°C for 30 seconds.

Characteristic of the filters’ properties before and after the filtration trial were done. It was found, that the surface reaction of the filter walls with molten metal, which resulted in local changes of the microstructure and phase composition, did not affect on expected filter lifetime and filtration did not cause secondary contamination of cast steel.

Open access

J.J. Sobczak, A. Karwiński, W. Leśniewski, P. Wieliczko, A. Gil, S. Pysz, P. Kowalski and N. Sobczak

Abstract

This study shown possibilities of Rapid Prototyping techniques (RP) and metal casting simulation software (MCSS), including non inertial reference systems. RP and MCSS have been used in order to design and produce essential elements for artificial heart. Additionally it has been shown possibilities of Fused Deposition Modeling (FDM) technique and DodJet technology using prototyped elements of rotodynamic pump. MAGMASOFT® software allowed to verify the cast kit heart valves model. Optical scanner Atos III enabled size verification of experimental elements supplied by rapid prototyping together with metal casting elements. Due to the selection of ceramic materials and assessment of molten metal – ceramic reactivity at high temperatures together with pattern materials selection model it was possible to design, manufacture a ceramic mould for titanium based alloys. The casting structure modification has been carried out by means of high isostatic pressure technique (HIP). The quality assessment of the casting materials has been performed using X-ray fluorescence (XRF), ARL 4460 Optical Emission Spectrometer, metallographic techniques and X-ray computed tomography.