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On the preparation of precursors and carriers of nanoparticles by water jet technology
Sitek, Libor ; Foldyna, Josef ; Martinec, Petr ; Klich, Jiří ; Mašláň, M.
High-speed water jet expanded into many fields of human activity over three decades due to its unique properties. Besides already traditional technological processes (cutting, machining, cleaning, demolition, etc.) it begins to find its way also to the comminution of mineral particles. The paper analyzes the possibility of particle comminution using an abrasive mixing head used to generate high-speed abrasive water jet and an impact of the jet to the solid perpendicular target made 256 from tungsten carbide. Phyllosilicate (i.e. layered silicate) particles of both micron and submicron sizes were made by this method. The particles are disintegrated along the cleavage surfaces. The method avoids the formation of secondary structural defects which is in contrast to mechanical methods of particles comminution (such as planetary milling, ball milling, milling by pressure air etc.).
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Ultrasonic pulsations of pressure in a tool for water jet cutting
Říha, Zdeněk ; Foldyna, Josef
Water flow in a tool for water jet cleaning and cutting is evaluated in this paper. There are ultrasonic pulsations of high pressure in the given domain. The efficiency of the amplification of high pressure pulsations in the transitional space between larger and smaller pipes is analysed. Three types of transitional spaces are compared in the paper: step change, conical and radius change of pipe diameters.
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Innovative Approach to Advanced Modulated Waterjet Technology
Kušnerová, M. ; Stoic, A. ; Foldyna, Josef ; Sitek, Libor ; Magurová, D. ; Harničárová, M.
The paper deals with a new formulation of theory for modulated waterjet technology by analytical model. The fundamental oscillations frequency for modulated waterjet technology has been investigated. This system generates a modulated liquid jet as a result of the resonant chamber introduction. The theoretical model was developed particularly on the basis of knowledge of the geometric dimensions of the system and the liquid pressures in order to predict the values of the fundamental frequencies of oscillations. The predicted oscillation frequencies were verified by laboratory measurements. It has been achieved a significant performance improvement in surface disintegration of material being machined.
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Erosion of metals by pulsating water jet
Klich, Jiří ; Foldyna, Josef ; Hlaváček, Petr ; Zeleňák, M. ; Ščučka, Jiří
The aim of the paper was to determine erosion effects of pulsating water jet impinging the surface of metal sample. The influence of repeated impacts of water pulses and impact velocity (operating pressure) on the erosion of metal surface was investigated. The development of erosion pattern with respect to number of impacts was analysed and discussed. It was found that erosion caused by repeated impacts of water pulses occurs in three stages. The stage of erosion of the surface can be determined by the behaviour of surface characteristics (such as Ra and Rz with respect to number of impacts of pulsating water jet.
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Water Jet 2011 - Research, Development, Applications (Proceedings of the Conference on Water Jetting Technology)
Sitek, Libor ; Zeleňák, M.
Conference Water Jet 2011 – Research, Development, Applications represents the second meeting of producers, users, designers and other people interested in technology of high speed water jet in the Czech Republic; it is a follow up to the successful first meeting held in 2009. The conference is organized by the Department of material disintegration of the Institute of Geonics of the ASCR, v. v. i. in Ostrava. With respect to the significant contribution of the International Visegrad Fund project to the activities related to the preparation and organizing of the conference, this year it was possible to hold the conference in the mountain hotel Sepetná in Ostravice at the foothill of the highest mountain in the Moravian– Silesian Beskydy Mountains – the Lysá Mountain. A wide spectrum of problems which are solved in submitted papers shows the recent trends in the application of the water jet technology in a great variety of branches of human activities. The considerable number of foreign participants of the conference proves the increasing interest in the technology in the whole Euroregion.
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