Project coordinator @ CEST: Andreas Laskos

Project abstract:

The aim of the planned project is to develop a technical process for the uniform electrochemical coating of stripper tubes made of stainless steel, which are used in urea production, with metallic zirconium. By applying the chemically resistant zirconium coating, the steel component is protected against corrosion. Currently, special chemically resistant stainless steels or bimetallic zirconium stainless steel pipes are used for this application. Zirconium is much more corrosion resistant than the best stainless steels available on the market, but pure zirconium tubes would not be economical due to the high price. In the case of bimetallic pipes, the outer tube is made of high-strength stainless steel and the inner tube is made of corrosion-resistant zirconium. One problem with the use of bimetallic pipes may be the infiltration of reaction media between the pipes, which can cause considerable corrosion. This problem cannot occur with an electrochemically coated pipe. Another advantage of an electrochemical process is the possibility to deposit thinner zirconium coatings and thus significantly save costs and energy. Zirconium coatings are nowadays produced on the one hand by PVD (physical gas phase deposition) or by electrochemical deposition at high temperatures in salt melts. Both processes are very expensive and energy-intensive. The deposition in salt melts also requires toxic chemicals. Alternatively, zirconium can be deposited from organic solutions or using ionic liquids. Platinum, copper, nickel, titanium, and stainless steel were used as substrates. It has been shown that zirconium can be deposited in principle but detailed studies on morphology, layer quality, kinetics, influence of electrolyte flow, etc. are missing. In particular, the coating on stainless steel is almost unexplored. Based on the results from the literature, the planned project will develop and optimize the electrochemical deposition process in ionic liquids to gain a compact zirconium layer on stainless steel. In addition, during the development of the coating process, care will be taken to ensure that the selection of materials, chemicals (ionic liquids, etc.) is suitable for an industrial process and that future upscaling is possible.

 General Info:

Program: Bridge

Funding Agency: FFG

Projekt duration: 03.01.2022- 02.07.2023

 Project partners: Schoeller-Bleckmann Nitec GmbH