High Temperature Corrosion Laboratories

Experimental Methods

Thermogravimetry Setup

This setup combines a high-resolution thermobalance with a IR furnace and a gas dosing and mixing system, constructed in the same way as the Short-Term Annealing Setup. The balance is fixated on a vibration-cushioned foundation and allows the rating of the mass gain of the exposed sample with a high resolution. For the Short-Term Annealing Setup a Quartz Micro Balance has been developed, which can be operated at temperature up to 1000 °C. The kinetics of oxidation and reduction behavior of vapor-deposited pure metals and subsequent electrodepo-sited binary model alloys in the defined forming gases can be described by means of gravi-metry with a very high accuracy.

Short-Term Annealing Setup

With this unique combination of two powerful IR furnaces, which allow fastest heating and cooling rates, and a high precision dosing and conditioning system for ultra pure gases and water, industrial short-term annealing processes can be simulated and important parameters like dew point, water/hydrogen or carbon dioxide/carbon monoxide ratio or oxygen leakages during process can be diversified. With a micro dosing pump the forming gas can be moisturized with a wide range of dew point from -80 °C to +75 °C (vacuum conditions), in order to achieve a defined oxygen partial pressure at the sample surface, which leads to a selective oxidation of the selected substrate elements.

Shared Analytical Devices

Considerable investment has been placed for advanced analytic, namely a set of four state-of-the-art oxygen sensors and  high-precision water-cooled or heated chilled or dew point mirror hygrometer. These sensors are installed in-line and enable well-controlled experiments. In addition, a mass spectro-meter with a unique gas transfer system can be connected. A ultrathin fused silica capillary is probing the reaction gas directly at the sample surface. This unique transfer system can be heated up to 350 °C to detect  reaction products, which are volatile at reaction temperature and it also realises the pressure reduction into the UHV recipient.

Liquid Zinc Spin Coater

This system combines a zinc spin coater with a sessile drop contact angle measurement device. In a attached reaction chamber, which can be connected to the gas conditioning system, the short-term  annealing process can be performed before the contact angle measurement or spin coating. This setup is compatible with UHV systems in order to allow sample transfer under UHV conditions with a transport vessel and allows the combination of contact angle detection and interfacial analysis of the undisturbed reaction zone. The spinning step makes it possible to remove the excess liquid zinc after a given time and to carry out time-resolved investigations of the interfacial reactions. 

Setup for Synchrotron XPS

One of the great advantages of synchrotron XPS is the high brilliance of the applied x-ray beam especially at lower energies. Which allows the varying the information depth of the resulting XPS-spectra. The mobile synchrotron unit makes it possible to perform the short-term annealing experiments under the same conditions as in the high-temperature lab at MPIE with the possibilities of a contemporary surface analysis by means of synchrotron x-ray photoemission spectroscopy. Another advantage of the direct connection of the short term annealing setup to an UHV-system is the possibility to transfer samples without any further oxygen contamination.

Related Projects

Diffusion and Segregation during Production of High Strength Steel Sheet

The “Christian Doppler Laboratory for Diffusion and Segregation Mechanisms during Production of High Strength Steel Sheet”, managed by Dr. Michael Rohwerder, focus on the diffusion and reactions of metallic and nonmetallic elements during the different steps during production of high strength steel sheet. One aim of the project is to  investigate the kinetics of grain boundary oxidation and therefore to try to simulate this. The experimental investigations are carried out in-situ by thermo-microbalance and ex-situ by cross-sectional investigations. With the Thermogravimetry setup the grain boundary oxidation during cooling after hot rolling is experimentally simulated under conditions where the partial pressure in the forming gas atmosphere is adjusted to the equilibrium oxygen partial pressure beneath the scale, i.e. the Fe/FeO equilibrium. The main focus is on the influence of different annealing conditions on the process related surface chemistry (i.e. segregation and selective oxidation of steels by tuning the short-term annealing parameters) for the future steel productions.

Annealing Procedures for Improving Hot Dip Galvanizing of High Strenght Steel

The inert oxides on the surface of modern high strength steels are a major problem for hot dip galvanizing. The aim of the RFCS-funded project “Annealing Procedures for Improving Hot Dip Galvanizing of High Strength Steels (NOVANNEAL)” is to develop concepts to avoid surface oxide formation by enhancing internal oxidation by increasing the dew point. Therefore, the wetting processes during hot-dip galvanizing of high strength steels has to be described as a function of the hydrogen amount in the forming gas at different dew points and the effect of a variation of the hydrogen and CO/CO₂ partial pressure at constant dew points has to be investigated. Also the effect of direct injection of O₂ and the effect of O₂ leakage during cooling is investigated. Deliverables are the fundamental understanding of gas kinetics and surface kinetics during cooling and the determination of the maximum oxygen amount in the gas jet cooling, which can be admitted. This understanding will also provide fundamentally novel information on the different non-equilibrium reactions involved in this process, providing the basis for possible future simulation.