|
|
Effect of chemical composition on the hot deformation behavior of selected iron aluminides
Šumšal, V. ; Schindler, I. ; Kopeček, Jaromír ; Šíma, V.
The influence of chemical composition on the deformation resistance of iron aluminides was studied by the plastometric tests on three types of Fe – 40 at. % Al based materialsalloys; especially the influence of zirconium and boron, respectively effect of fine TiB2 particles addition was investigated. All materials were prepared using the identical procedure. The samples were pre-heated to a temperature of 1200 °C and then deformed at temperatures from 800 to 1200 °C, the nominal strain rate was 0.05 s-1, 0.4 s-1-1, 4 s-1 and 30 s-1. The relationship describing the maximum deformation resistance of aluminides depending on the temperature-compensated strain rate was derived from obtained data. The values of activation energy and hot deformation resistance of the studied materials were compared and the differences interpreted in terms of physical-metallurgical effects of additives.
|
|
|
Small-Volume Reactive Metal Alloys Prepared by Electron Beam Melting
Zobač, Martin ; Vlček, Ivan ; Zobačová, Jitka ; Rek, Antonín
The paper deals with the preparation of small volumes of reactive metal alloys (particularly titanium), utilizing an electron beam as the heat source. The melting was performed in a vacuum environment in order to prevent the compounds from reacting with atmospheric components. The water-cooled crucible avoids any contamination of the alloy, which would have otherwise arisen during the heating of the materials. The composition of resulting alloys were then investigated by energy-dispersive X-ray spectroscopy
|
|
|
Dynamic impact tester of hard thin coatings
Grossman, Jan ; Dupák, Libor ; Fořt, Tomáš ; Sobota, Jaroslav
An impact test has been used to evaluate the impact wear resistance of nanostructured hard coatings using a system developed at the Institute of Scientific Instruments in collaboration with the Brno University of Technology. After the test, wear scars were evaluated by means of scanning electron microscope, spectral analyses and profilometer. The impact test offers an important new method for the determination of both the fracture toughness and wear behaviour of hard thin coatings.
|
|
| |
|
|
Thin Metallic Layers Structured by E-beam Lithography
Horáček, Miroslav ; Kolařík, Vladimír ; Urbánek, Michal ; Matějka, František ; Matějka, Milan
The group of electron beam lithography runs the laboratory equipped with a shaped beam electron writer (BS600) and the basic technology for the lithographic process. The group is able to prepare micro and nano structures in thin layers of metals and other materials; including the characterization of the realized structures (using AFM, SEM, and CLSM). Within a few months (in the frame of the 'ALISI' project) a new e-beam writer with a better resolution will be installed; it will enable the realization of the actual structures in a better quality and the development of new structures with a very high innovation potential.
|
|
|
Influence of annealing to stress in CNx:(H) films observed by SLEEM
Mikmeková, Eliška ; Mikmeková, Šárka ; Müllerová, Ilona ; Sobota, Jaroslav
The effect of high residual stress on the quality of thin sputtered carbon nitride films has been studied by Scanning Low Energy Electron Microscopy (SLEEM). Basically, two different types of stress can be identified in thin films: compressive stress and tensile stress. Compressive stress leads to wrinkling and film delamination and tensile stress can cause the fracturing of thin films. Experiments were made in the Tescan TS 5130 MM equipped with the Cathode Lens system (CL), which enable us to observe samples at arbitrary landing energies of the illuminating electrons. Operating of a SEM at low energies offers several advantages: an increase of materials contrast via low energy, high ratio SE, BSE signal and noise, smaller interaction volume and elimination of charging effects. The effect of annealing in vacuum to residual stress (calculated from Stoney’s equation) was measured. The porous character of films was observed by thermal desorption spectroscopy (TDS).
|
|
|
Manufacturing of Solar Absorber by Unconventional Methods
Mrňa, Libor ; Lidmila, Z. ; Podaný, K. ; Forejt, M. ; Kubíček, J.
Solar absorbers of flat type have the advantage of relatively simple production, but on the other hand, they have lower thermal efficiency and require perpendicular incidence of solar radiation on their surface. This contribution presents new type of solar absorbers where the above-mentioned disadvantages are reduced while keeping relative production simplicity. The solar absorber is characterized by the creation of the appropriate spatial structure in sheet metal by forming through a technology of drawing in flexible tools. This spatial structure not only increases the heat-transfer surface but also eliminates the need for perpendicular incidence of the incoming solar radiation. The component with this structure is fixed to the rear side of the absorber by laser welding. Inlet holes for the fluid are produced by Flow drill method.
|
|
|
Institute of Scientific Instruments: An Overview Presenatation
Kolařík, Vladimír ; Zobač, Martin ; Fořt, Tomáš ; Vlček, Ivan ; Dupák, Libor ; Mikmeková, Šárka ; Mikmeková, Eliška ; Mrňa, Libor ; Horáček, Miroslav ; Sobota, Jaroslav
The aim of this contribution is to present the Institute of Scientific Instrument of the Academy of Sciences of the Czech Republic, mainly from the potential of applied research viewpoint. It covers mainly the six application fields including material study of metals and alloys, nano layer residual stress observation methods, 2 kW fibre laser, impact testing of hard coatings, e-beam welding, machining and engraving, and finally e-beam lithography. Recently achieved results as well as the new application potential are presented. Furthermore, each topic is assumed to have a separate presentation prepared in more details within this event. A brief overview follows. Scanning low energy electron microscopy (SLEEM) is increasingly becoming recognized as a valuable analytical tool in the field of materials science. The SLEEM is also used for observation of compressive stress in nano layers that leads to wrinkling and film delamination. Using the fibre laser, we can offer 3D laser welding and cutting of various type of materials and laser surface hardening too. For the hard coatings testing and evaluation of their impact resistance a new method was suggested (Dynamic Impact Wear Test). During testing the specimen is cyclically loaded by tungsten carbide ball that impacts of the coating/substrate surface. In house e-beam welding machine allows for welding, machining, engraving and other utilizations of intense electron beam. The group of micro lithography is able to prepare micro and nano structures in thin layers of metals and other materials; including the characterization of the realized structures
|
guest ::
