Preparation and evaluation of properties of cast metallic foams with regular inner structure

Lately we encounter still more new applications of metallic foams, as well as possible methods of their manufacture. These metallic materials have specific properties, such as large rigidity at low density, in some cases high thermal conductivity, capability to absorb energy, etc. The work is focused on the preparation of these materials using conventional casting technology, which ensures rapid and economically feasible method for production of shaped components. In the experimental part we studied conditions of casting of metallic foams with a regular structure made of ferrous and non-ferrous alloys. For thus obtained castings we evaluated the achieved microstructure and mechanical properties, which determine the possible use of these materials. The samples were subjected to compression tests, by which we investigated deformation behaviour of selected materials and determined the value of energy absorption.Web of Science6231646164

Manufacturing of cast metal foams with irregular cell structure

Metallic foams are materials of which the research is still on-going, with the broad applicability in many different areas (e.g. automotive industry, building industry, medicine, etc.). These metallic materials have specific properties, such as large rigidity at low density, high thermal conductivity, capability to absorb energy, etc. The work is focused on the preparation of these materials using conventional casting technology (infiltration method), which ensures rapid and economically feasible method for production of shaped components. In the experimental part we studied conditions of casting of metallic foams with open pores and irregular cell structure made of ferrous and nonferrous alloys by use of various types of filler material (precursors).Web of Science152585

Design of Oil Pumpjack

Cílem bakalářské práce je navrhnout funkční konstrukci ropné pumpy. Práce je rozdělena na tři hlavní části−teoretickou, výpočetní a návrhovou. Teoretická část popisuje tématiku těžení ropy a vývoj konstrukcí ropných pump v průběhu historie zakončený současnými typy. Výpočetní část je konkrétní koncept údajů a předpokladů, ze kterých vychází návrh geometrie a následné výpočty. Poslední část se věnuje návrhu a kontrole vybraných uzlů společně s výslednou vizualizací modeluThe purpose of this bachelor’s thesis is to design a functional construction of a pumpjack. The thesis is divided into three main parts−theory, calculations and design. The first part describes the topic of oil extraction and the evolution of the pumpjack in history and shows its historical and present use. The fourth part introduces the specific concept of the project consisting of data that will be used throughout the calculations. The third part focuses on the design and control of selected parts and the final visualization of the model is presented

Evaluation of properties of cast metal foams with irregular inner structure

Internal structure of metal foams is one of the most important factors that determine its mechanical properties. There exists a number of methods for studying the nature of the inner porous structure. Unfortunately most of these processes is destructive and therefore it is not possible to reuse the sample. From this point of view, as a suitable method seems to be the ability of using the so-called X-ray microtomography (also micro-CT). This is a non-destructive methodology used in a number of fields (industry, science, archaeology, medicine) for a description of the material distribution in the space (e.g. pores, fillers, defects, etc.). In principle, this technology works on different absorption of X-ray radiation by materials with changing proton number. The contribution was worked out in collaboration with experts from the Faculty of Electrical Engineering and Computer Science of the VSB-Technical University of Ostrava and it is focused on the analysis of internal structure of the metal foam casting with irregular arrangement of internal pores by using micro-CT. The obtained data were evaluated in the commercial software VGStudio MAX 2.2 and in the FOTOMNG system. For the evaluation of these data a new specialized module was introduced in this system. Several methods of pre-processing the image was prepared for the measurement. This preliminary processing consists, for example, from a binary image thresholding for better diversity between the internal porosity and the material itself or functions for colour inversion.Web of Science6341851184

Investigation of the thermomechanical properties and microstructure of special magnesium alloys

Thanks to their high specific strength together with a low density, magnesium-based alloys have an extensive potential for the use of their castings in automotive industry. The castings based on these materials show relatively good mechanical properties that decrease significantly with an increasing temperature of their thermal exposure. The aim of this work is to study the properties of two alloys commonly used (Mg-Al-Zn, Mn type). From the studied materials the test castings were made and these were formed into the test bars used for a tensile test. This test was carried out within the temperature range of 20–300 °C. Further on, the tests of the thermomechanical properties were complemented with a microstructure analysis with the aim of checking metallurgical interventions (the effect of inoculation).Web of Science47450650

Control of the metallurgical processing of ICDP cast irons

The article is focused on the use of the measurement of oxygen activity for the management of cast-iron metallurgical processing in the operating conditions of a centrifugal-roll casting foundry. The paper presents the results of the oxygen-activity measurement recorded during the metallurgical processing of cast iron from the beginning of the melting to the inoculation of cast iron. The measurement of oxygen activity was made with specifically developed devices and the probes with a high sensitivity designed for measuring aO in cast iron by Heraeus Electro-Nite Celox Foundry. The oxygen activities in cast iron correlate with the properties of cast iron.Web of Science48568868

Influencing of foundry bentonite mixtures by binder activation

Although new moulding processes for manufacture of high quality castings have been developed and introduced into foundry practice in recent years, the green-sand moulding in bentonite mixture still remains the most widely used technology. Higher utility properties of bentonite binders are achieved through their activation. This contribution is aimed at finding a suitable activating agent. A number of sodium salts and MgO based agents has been chosen. In the framework of the experiment the swelling volume of chosen agents was tested and technological parameters of a bentonite mixture with a binder activated with the studied agents were determined.Web of Science55110

Thermophysical properties and microstructure of magnesium alloys of the Mg-Al type

Generally speaking, magnesium alloys of the Mg-Al type are used as structural materials, but their disadvantage lies in their low heat resistance. The addition of suitable alloying elements can be positive, as it makes it possible to achieve good thermo-mechanical properties. For the application of a specific material for thermally stressed cast parts it is necessary to consider the extent of their linear and volumetric changes at elevated and high temperatures. The aim of this paper is to study the behaviour of selected magnesium alloys based on Mg-Al during heat stress conditions in order to simulate real conditions using dilatometric analyses. These properties were evaluated on samples of alloys prepared by gravity casting in metallic moulds. The effect of the metallurgical processing of the alloys on the studied parameters was also investigated.Web of Science49581180

Cast cellular metals with regular and irregular structures

An appropriate way to reduce the weight of manufactured parts without adversely affecting their strength is to use porous metallic materials with different internal arrangements of the intentionally created cavities. Porous metallic materials can be made from liquid metal, from powdered metal, metal vapours, or from metal ions. The aim of this research was to verify the possibilities of producing metallic foams by conventional foundry processes, to study the process conditions as well as the physical and mechanical properties of the metal foams produced. The experiments demonstrated the possibility of manufacturing castings with both a regular cellular structure and a solid skin in a single casting operation using different kinds of preform made from commonly used resin-bonded core mixtures. From the perspective of the need to destroy the preforms after the metal’s solidification it seems a very interesting prospect to produce preforms from different salts.Web of Science48217917

Uporaba prekurzorjev za izdelavo litih kovinskih pen

The presented work was devoted to the development of the production processes for metallic foams, which were based on conventional casting technologies. The use of the standard casting processes and standard materials made it possible to identify the range of metallic foams amongst affordable materials, thereby making a full use of their application potentials. The experimental part was focused on the development and subsequent optimization of the casting processes for manufacturing cast metallic foams with irregular inner-cell structures, and especially on the development of the technology of infiltrating molten metal into a mold cavity filled with precursors.Avtorji predstavljajo razvoj procesa izdelave kovinskih pen, ki temelji na konvencionalnih tehnologijah litja. Zaradi uporabe standardne livarske prakse in materialov spadajo kovinske pene med dostopne materiale, in tako je mogoč poln izkoristek njihovega potenciala. Eksperimentalni del študije je bil osredotočen na razvoj in takojšnjo optimizacijo livarskega postopka izdelave kovinskih pen z nepravilno notranjo celično strukturo. Delo je bilo še posebej osredotočeno na razvoj tehnologije infiltracije kovinske taline v votlino orodja, ki je bila pred tem napolnjena s predhodno surovino (prekurzorjem).Web of Science53219118