- Number of measuring channels: 2
- Max. Current per channel: ± 500 mA
- Max. Counter electrode voltage: ± 15 V
- Current resolution: 500 pA
- Potential resolution: ± 1 mV
- Test sample: Discs: Æ 10 - 32 mm, thickness max. 4 mm
- Reference electrode: Saturated Ag/AgCl electrode with a reference voltage of +197 mVH compared to the normal hydrogen electrode
- Test medium: electrolytes according to customer specifications
The topics of friction, lubrication and wear are becoming increasingly important against the background of environmental and climate protection, energy efficiency and electric mobility. The research focus of the department of surface technology is therefore the development of tribological functional coatings. On the one hand, this includes novel friction-reducing hard material coatings to increase energy efficiency and the service life of transmission components, especially for rolling bearings and gears. On the other hand, tribological functional coatings are also used for coating high-performance cutting and forming tools. For cutting tools, the development goals are dry machining, hard machining, tools for workpiece materials that are difficult to machine, and increasing the cutting path and metal removal rate. For forming tools, the focus is on dry machining, increasing tool life and workpiece quality.
Increasing the energy efficiency and service life of gearbox components
Increasing the energy efficiency and service life of gear components by using surfaces that minimize friction and wear is an important future topic for climate protection. This applies both to primary energy generation and to the industrial, commercial and mobility sectors. The great importance of tribology for climate protection is impressively illustrated in the current study “Tribology in Germany: cross-sectional technology for reducing CO2 emissions and conserving resources” by the Gesellschaft für Tribologie e.V. (2019).
For example, this study shows that a compact and therefore lightweight design of electric motors requires high speeds in the range of 10,000 to 30,000 rpm. This results in numerous tribological challenges for the reduction gears required. In addition to minimizing friction and wear and the use of new low-viscosity lubricants, triboacoustic emissions also play a major role in such gearboxes.
This is because these emissions are often in a frequency range that is unpleasant for people and are easier to hear due to the significantly lower overall noise emissions of electric vehicles compared to combustion engines. In the future, friction, lubricant film formation, wear and the acoustic emissions of high-speed transmission components must therefore be controlled by various measures such as friction-reducing hard coatings or targeted microstructuring of the surfaces of the machine elements used.
In the area of hard material coating for high-performance cutting tools, the topics of dry machining, machining of difficult-to-cut workpiece materials such as titanium or cobalt-chrome alloys from the medical sector, as well as increasing the cutting path and metal removal rate, are of great importance. For the coating of forming tools (cold forging), the focus is on dry machining and increasing tool life. If cooling lubricants are dispensed with completely, subsequent cleaning processes are no longer necessary. New tool coatings that enable dry machining with the same tool life and workpiece quality therefore make a direct contribution to environmental protection and resource efficiency.
The Surface Technology department focuses on the application of tribological hard coating systems using the PVD magnetron sputtering process. Magnetron sputtering is an industrially used physical vapor deposition process (PVD). In collaboration with project partners, hard coatings deposited using the PVD-Arc process are also being investigated. In general, the environmental compatibility of physical vapour deposition processes is relatively good, despite the complex vacuum system technology required, as no or only a few environmentally harmful waste products are produced during arc evaporation in the PVD arc process and during cathode sputtering in magnetron sputtering of the mostly metallic target materials.
PVD processes enable the deposition of a very wide range of metallic and non-metallic coating materials. Reactive PVD processes can also be used to incorporate light elements such as nitrogen, carbon, oxygen, but also boron or hydrogen into the coatings, so that in combination with metallic target materials such as titanium, chromium, vanadium, molybdenum, zirconium, tungsten, aluminum, etc., the corresponding nitrides, carbides, oxides or borides can also be deposited. In this way, an almost unlimited number of different hard materials can be deposited using PVD processes. These include, in particular, purely covalently bonded hard materials such as diamond or diamond-like amorphous carbon layers.
In the field of friction-minimizing coatings for rolling bearing rings and gears, the Surface Technology department is working both on the further development of hydrogen-containing amorphous carbon coatings (a-C:H) and on the development of new types of self-lubricating hard coating systems based on various PVD solid lubricant coatings in combination with transition metal nitride coatings (TiAlN, CrAlN, ...). In addition to the coating composition and layer structure, the tribology can also be influenced by setting defined surface topographies in the micrometer range. The microstructuring of the coatings or substrates prior to coating is carried out in close cooperation with the Laboratory for Micro Machining, as well as with partner institutes from the field of laser processing.
The trend towards the increasing integration of additional functions such as corrosion protection, electrical, optical, acoustic or antimicrobial properties in functionalized surfaces of tools and machine elements is also continuously leading to new research topics. Other areas of research in the Surface Technology department include new metallic alloys produced using PVD processes, corrosion research and sol-gel coating processes.