Skip to content

Electrochemical high-throughput characterization of metallic micro samples (SFB 1232)

Metal corrosion refers to a process that involves degradation of the material functionality. The annual costs of corrosion damages amount to billions of euro. Corrosion phenomena, like passivity or pitting corrosion, can be determined by electrochemical characterization methods.

 

 

  • Abbildung 1: Cyclovoltammogramm verschiedener Werkstoffe in 0,1 molarem Phosphatpuffer; die Höhe der Stromdichte steht in Zusammenhang mit der Passivität der Metalle - der rostfrei Stahl (X5CrNi18-10) zeigt kleinere Stromdichten und somit weniger Metallauflösung

    Figure 1: Cyclic voltammograms of different alloys in 0.1 M phosphate buffer. The stainless steel (X5CrNi18-10) shows a lower passive current and thus a better passivation.

  • Abbildung 2: Impedanzspektroskopie rundgekneteter Edelstahldrähte (X5CrNi18-10); durch die unterschiedliche Umformgeschwindigkeit (v= 10mms-1/5 mms-1/1 mms-1) variiert das Mikrogefüge (Korngröße und Martensitgehalt), was durch eine Änderung der Impedanz deutlich wird.

    Figure 2: Electrochemical impedance measurements of cold formed stainless steel. Due to different forming velocities (v = 10mms-1/5 mms-1/1 mms-1) different martensite contents can be achieved. These differences lead to changes in the passivity and thus the electrochemical impedance.

  • Abbildung 3: Elektrochemisches Potentialrauschen; 100Cr6 in 0,1 molarer phosphatgepufferter Salzlösung

    Figure 3: Electrochemical noise measurement in 0.1 M phosphate buffered saline.

  • Abbildung 4: Korrosionsangriff an X46Cr13 in unterschiedlichen Elektrolyten; links 0,1 M Phosphatpuffer mit 3,5 wt.-% NaCl; rechts 3,5 wt.-% NaCl Lösung; es ist zu erkennen, dass in der phosphatgepufferten Salzlösung (links) nur Lochkorrosion auftritt, während in der reinen Salzlösung (rechts) die Lochkorrosion von flächiger Korrosion überlagert ist.

    Figure 4: Corrosion damage due polarisation scans in different electrolytes; left: 0.1 M phosphate buffe with 3.5 wt.-% NaCl; right: pure 3.5 wt.-% NaCl solution. By adding phosphate buffer tot he electrolyte (left) pure pitting corrosion can be observed. Without phosphate buffer the pitting corrosion is overlapped by additional dissolution processes.

  • Abbildung 5: Höhenprofil nach Lochkorrosion an rundgeknetetem X5CrNi18-10 Draht

    Figure 5: Height profile after pitting corrosion on cold formed stinless steel

The aim of the project is the characterization of corrosion and material properties of micro samples by electrochemical methods like cyclic voltammetry, impedance spectroscopy and electrochemical noise technique. One main research question is the correlation of electrochemical measurements on micro samples in short time periods (seconds or minutes) and corrosion phenomena on metallic components in real time (several years). An additional research focus are the effects of changes in the micro structure on the ability to form protective passive layers.

The project ‘Electrochemical high-throughput characterization of metallic micro samples’ is part of the Collaborative Research Center SFB 1232 ‘Farbige Zustände’ about the development of new high-performance materials. As part of the Collaborative Research Center micro samples of different composition and treatment have to be generated and characterized. This project is responsible for the electrochemical characterization of the samples and passivity is of particular interest.

The passivity of iron-based materials is caused by a formation of an oxide layer on the surface of the metal. This passive layers can protect the metal surface against corrosion attacks. The stability of the passive layer is related to the composition and the micro structure of the alloy.  A possibility to improve the passive layers through micro structure optimization has to be explored by high throughput electrochemical measurements.

Relevant publications

I. Bösing et al. (2019) AIP Advances 9, 065317. https://doi.org/10.1063/1.5094615
I. Bösing et al. (2018) MATEC Web of Conferences 190, 04002, http://doi.org/10.1051/matecconf/201819004002.
I. Bösing et al. (2017) International Journal of Corrosion 9425864, http://doi.org/10.1155/2017/942586

Relevant files

Contact:

Bösing, Ingmar, M. Sc.
Room UFT 2220
Fon 0421 - 218 - 63466

ingmar.bösingprotect me ?!uni-bremenprotect me ?!.de

Further information

DFG Collaborative Research Center "Colored States" (SFB 1232).
Project D03.