INSTITUTE OF SCIENTIFIC INSTRUMENT: AN OVERVIEW PRESENTATION

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1 Abstract INSTITUTE OF SCIENTIFIC INSTRUMENT: AN OVERVIEW PRESENTATION Vladimír KOLAŘÍK, Martin ZOBAČ, Tomáš FOŘT, Ivan VLČEK, Libor DUPÁK, Šárka MIKMEKOVÁ, Eliška MIKMEKOVÁ, Libor MRŇA, Miroslav HORÁČEK, Jaroslav SOBOTA Ústav přístrojové techniky AV ČR, v. v. i., Královopolská 147, CZ Brno, 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 Key words: E-beam microscopy, welding and lithography; laser cutting; impact test; wear resistance; hard coatings. 1. SCANNING LOW ENERGY ELECTRON MICROSCOPY (SLEEM) Scanning low energy electron microscopy (SLEEM) presents a new approach to materials research, which has several potential advantages over the traditional scanning electron microscopy (SEM) currently in use in research institutes and laboratories across the world Study of metals and alloys using SLEEM This technique enables us to observe specimens at arbitrary landing energy of primary electrons and by means of slow and very slow electrons reflected from the sample and effectively detected in their full angular distribution the structure is imaged at high spatial resolution and high contrast is obtained between differently oriented grains in polycrystals, between areas with different chemical composition and also with decreasing landing energy of primary electrons increase the topographic contrast. Good prospect of the SLEEM in materials science follow from many opportunities the method provides not only in fundamental but also in analytic study of materials important for practice Observation of compressive stress in nano layers using SLEEM One of the key factors for wider use of the films in industry is a thickness greater than a few nanometers, which is a problem due to a high value of residual stress. Basically, two different types of stress can be identified in thin films: compressive stress and tensile stress. Compressive stress leads to wrinkling and film 1

2 Fig. 1. SLEEM images of AZ 96 alloy. The electron impact energy are 9 kev (a), 8 kev (b), 7 kev (c), 6 kev (d), 5 kev (e), 4 kev (f), 3 kev (g), 2 kev (h), 1 kev (i) and 0.5 kev (j). A Atomic %: Mg=5.50 Al=55.40 Mn=31.06 Zn=6.45; B Atomic %: Mg=72.49 Al=22.24 Mn=0.07 Zn=5.86; C Atomic %: Mg=58.21 Al=27.03 Mn=0.04 Zn=15.25; D Atomic %: Mg=89.91 Al=7.69 Mn=0.08 Zn=1.95; E Atomic %: Mg=68.03 Al=24.74 Mn=0.23 Zn=6.96. delamination, and tensile stress can cause the fracturing of thin films. For observation of the consequences of residual stress, we used Scanning Low Energy Electron Microscopy (SLEEM). Experiments were made in the Tescan TS 5130 MM and FEI Megallan XHR SEM equipped with the Cathode Lens system (CL), which enable us to observe samples at arbitrary landing energies of the illuminating electrons. Operation 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. 2. DYNAMIC IMPACT TESTER OF HARD THIN COATINGS An impact test has been used to evaluate the impact wear resistance of nano structured 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 behavior of hard thin coatings. Many investigators have used conventional erosion tests to measure the erosion rates of coatings, in the same manner as for bulk materials. The need is obvious for both a standardized test procedure and standard methodology in order to assess the dynamic resistance and toughness of thin coatings. Our approach is based on a dynamic impact tester and a very promising approach towards a solution of this task. The basic principle of the dynamic impact tester is the cyclic loading by an indentor, which impacts upon the surface of the coatings/substrates. A mechanical diagram is shown in Fig. 2. The most important part of tester is the moving part, carrying the indentor, which is in the ball shaped and made of a standard tungsten carbide material having a diameter of 5 mm and of a defined surface shape and roughness. The effect of a variable electromagnetic field causes repetitive impacts of the indentor with 2

Fig. 2. Mechanical diagram of the dynamic impact tester Fig. 3. Dynamic tester in climatic chamber a constant frequency and given impact force onto the tested surface.

3 Fig. 2. Mechanical diagram of the dynamic impact tester Fig. 3. Dynamic tester in climatic chamber a constant frequency and given impact force onto the tested surface. The resulting elastic-plastic surface deformation is proportional to the dynamic wear of the coatings. Synchronization of the dynamic movements of the indentor is controlled by a computer program, as are the adjustments of the impact force as well as the total number of impacts. Tab I. Technical parameters of the tester Range of impact force Frequency of impacts (150 ~ 600) N 8 Hz Total number of impacts 1 ~ 10 5 impacts Distance of indentor s travel 2.4 mm Measurement temperature (25 ± 5) C Adjustable relative humidity with accuracy (0 ~ 97) % ±2 % The results that can be achieved with these dynamic impacttests for different coatings for,substrates and treatments cannot be accomplished by static tests. Their application, especially in the case when the coatings are locally and periodically loaded, cannot be replaced by other types of tests. In the case of testing at the indentor s higher loads, the results are achieved in a relatively short time frame and are altogether sufficient for a rough evaluation of the proposed structure of the coatings. So far tens of millions of impacts have been done on the existing equipment with reproducibility in range of a few percent. 3. CENTRE OF ADVANCED LASER TECHNOLOGY The workshop is equipped by fiber laser from IPG photonics with cw power 2 kw, 6 axe robotics arms ABB IRB 2400 (accuracy of positioning better 0.1 mm), 2 axe rotary positioner IRBP 250, laser welding head Precitec YW30 and laser cutting head Precitec YRC and clamping table Fig. 4. Aim of our research is study of dynamics of laser welding process, its active stabilization and optimization. Within the bounds of contractual research we offer 3D laser welding Fig. 5. and cutting various type of materials and laser surface hardening too. Welding depth is 6 mm, cutting thickness 5 mm (in dependency of cutting method), depth of hardening approx. 1 mm Fig. 6. 3

Fig. 4. Workshop with laser, robotic arms and clamping table 4.

micromachining, vacuum brazing, development and manufacturing of vacuum electric feedthroughs, etc. [2]. 4.1.

mm and depth 160 mm. All welders are equipped with 60 kv / 2000 W electron guns [3], [4]. We can do standard weld joints for vacuum systems, as well as for automotive, nuclear or any other industry.

4 Fig. 4. Workshop with laser, robotic arms and clamping table 4. ELECTRON BEAM TECHNOLOGIES GROUP The group is concerned with both the development of technologies and the design and construction of technological equipment in the fields of electron beam welding and micromachining, vacuum brazing, development and manufacturing of vacuum electric feedthroughs, etc. [2] Electron Beam Welding Our laboratory utilizes an Electron Beam Welding Machine (EBWM), with cylindrical chamber with diameter 600 mm and depth 490 mm and two desktop EBWM, with chamber diameter 230 mm and depth 160 mm. All welders are equipped with 60 kv / 2000 W electron guns [3], [4]. We can do standard weld joints for vacuum systems, as well as for automotive, nuclear or any other industry. Most common welds are circular, both radial and axial. 4 Fig. 5. Cross section of weld duplex steel 5 mm (left) Fig. 6. Surface hardening of driveshaft (right) However, the welding trajectory can be arbitrary (e.g. rounded square, ellipse). Electron beam welds are characteristic by their knife-like shape, with depth-to-width ratio going up to 15:1. We can weld stainless steel up to 15 mm. Wide range of materials can be welded by electron beam: stainless steel, copper or aluminum, reactive (e.g. titanium) and high melting point metals (tungsten), as well as combinations of materials with considerably different metallurgical properties, e.g. stainless steel-al, stainless steel-mo, Ti-Al.

Fig. 7. E-beam welding machine 4.2. Vacuum Brazing We provide vacuum brazing using various solders. Most commonly used are copper, silver and nickel brazing fillers.

For this purpose our laboratory utilizes two vacuum furnaces, used also for annealing. The first is laboratory vacuum furnace of our design for batch size diameter 150 mm and height 200 mm.

Maximal batch size is 350 mm in width and 490 mm in height. Maximum long term temperature is 1400 C. 4.3. Vacuum Feedthroughs In our department we develop and produce vacuum feedthroughs based on glass-to-metal seal (matched kovar-glass or compression seal).

5 Fig. 7. E-beam welding machine 4.2. Vacuum Brazing We provide vacuum brazing using various solders. Most commonly used are copper, silver and nickel brazing fillers. For joining metals with brittle non-metallic materials, ductile active brazing solders have been introduced. For this purpose our laboratory utilizes two vacuum furnaces, used also for annealing. The first is laboratory vacuum furnace of our design for batch size diameter 150 mm and height 200 mm. For objects not exceeding 18 mm in diameter the height can be extended. Maximum working temperature is 1100 C. The second is a modernized vacuum furnace PZ 810 by former company Tesla. Maximal batch size is 350 mm in width and 490 mm in height. Maximum long term temperature is 1400 C Vacuum Feedthroughs In our department we develop and produce vacuum feedthroughs based on glass-to-metal seal (matched kovar-glass or compression seal). So far we have developed several types for different purposes like seven and twelve pin feedthroughs for temperature range 196 C to +400 C or high current or high pressure Fig. 8. Vacuum feedthroughs Fig. 9. Examples of e-beam welded parts 5

6 Fig. 10. E-beam pattern generator feedthroughs (suitable also for nuclear industry) for temperature range 60 C to +300 C. Apart from already developed types we are able to design and produce feedthroughs according to customer requirements. The feedthroughs can be welded to custom flanges. 5. ELECTRON BEAM LITOGRAPHY The group of micro lithography runs the laboratory equipped with a shaped beam electron writer BS600 Fig. 10. and the basic technology for the lithographic process [1]. 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 higher 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. ACKNOWLEDGEMENT This work was partially supported by European Commission and Ministry of Education, Youth and Sports of the Czech Republic (project No. CZ.1.05/2.1.00/ ALISI). REFERENCES [1] [2] [3] Vlček, I. - Zobač, M. - Dupák, L. - Dupák, J. - Kapounek, P. Desktop electron beam welder MEBW-60/2. Fine mechanics and optics,, 53, 2008, s , ISSN [4] Zobač, M. - Vlček, I. Electron Beam Welding in ISI Brno: Past and Present. Recent Trends (11th seminar), Brno: ÚPT AV ČR, 2008, s , ISBN

THIN METALLIC LAYERS STRUCTURED BY E-BEAM LITHOGRAPHY. Miroslav HORÁČEK, Vladimír KOLAŘÍK, Michal URBÁNEK, František MATĚJKA, Milan MATĚJKA

THIN METALLIC LAYERS STRUCTURED BY E-BEAM LITHOGRAPHY Miroslav HORÁČEK, Vladimír KOLAŘÍK, Michal URBÁNEK, František MATĚJKA, Milan MATĚJKA Ústav přístrojové techniky AV ČR, v. v. i., Královopolská 147,