Helmholtz-Zentrum Geesthacht, Tuesday, 22-May-2012 04:39:48 CEST
http://www.hzg.de/institute/materials_research/structure/magic/corrosion_and_surface_technology/profile/index.html.en

Profile

The Corrosion and Surface Technology department is headed by Dr.-Ing. W. Dietzel; six staff, whose work is regularly complemented by guest scientists, are currently employed in the department.

Magnesium surface attacked by corrosion Magnesium surface attacked by corrosion

Although magnesium is an extremely base metal, magnesium-based materials are corrosion-resistant when exposed to air. Corrosion protection is only necessary when such components are exposed to aggressive media, e.g. a saline, damp atmosphere or sea water. This is particularly true when magnesium is connected to other, more noble metals, for example by welding. This is why the WZK department develops anti-corrosion coatings which are still effective if damaged. Magnesium surface attacked by corrosion
In addition, the department’s work focuses on improving the corrosion resistance of magnesium alloys.

PVD coating on magnesium PVD coating on magnesium

There is growing interest in magnesium as a material for implants which are needed only for temporary fixation and are later removed — possibly in a second operation. Implants made of magnesium are gradually dissolved by the surrounding bodily fluids and absorbed by the body without harm. Here, the WZK department is working on the development of components made of magnesium materials and coatings which dissolve in the body according to a set timescale.

Metallic structural materials and their welded joints are at greater risk when these components are subject to a combination of mechanical tensile or alternating stresses and corrosion attack. Then, even with low loads and strains, fast-growing cracks can occur, leading to sudden failure due to stress corrosion or corrosion fatigue. A frequent cause is hydrogen, which is generated in corrosion processes and then permeates the material, making it brittle. This embrittling is a problem, for example, for tanks used to store hydrogen as an energy source (Nanotechnology department). The department specialises in

The department specialises in:
  • electrochemical corrosion investigations,
  • tests on hydrogen embrittlement, stress corrosion and corrosion fatigue according to ASTM, ESA and ISO specifications,
  • development of anti-corrosion coatings for magnesium components,
  • exposure tests under corrosive conditions,
  • clarification of corrosion-related causes of damage.