By coating a less expensive substrate material with a thin layer of precious metal, desirable characteristics (e.g. catalytic properties or protective layers) can be added to a material. Since only a minimal amount of precious metal is used, it is an economical and ecological method to enhance the source material.
Solutions for Electrode Coatings and Protective Coatings
Heraeus Precious Metals offers various precious metals compounds suitable for adding superior properties to substrate materials via coating. Our portfolio includes solutions for electrode coatings and protective coatings and can be found below. In addition, we also offer solutions for electroplating .
Precious metal compounds are often used for electrode coatings – especially for mixed metal oxide (MMO) electrodes. Electrodes are used in electrochemical processes – for example to produce chemicals via electrolysis or to prevent corrosion.
To produce these MMO electrodes – which are usually dimensionally stable anodes (DSA) – a substrate (e.g. titanium plate or mesh) is coated with a thin layer of precious metals (usually ruthenium and iridium) to provide enhanced properties to the anodes.
Key Benefits of MMO Electrodes
One of the key benefits of MMO electrodes is a lower overpotential compared to other electrodes (e.g. graphite) for electrochemical reactions – especially regarding evolution of hydrogen, oxygen or chlorine. A good example is the chlor-alkali process which uses electrolysis of a brine solution to produce chlorine and caustic soda. MMO electrodes are used as anode for chlorine evolution. Due to the lower overpotential at the MMO electrode, the required energy that needs to be applied for the electrochemical reaction is lower as well. As a result, precious metal coatings help to reduce energy costs for industrial processes and have a positive impact on the environment as less energy is needed to run the process.
On top, precious metals coatings are inert (non-reactive) and resistant against corrosive environments. An example is the chlor-alkali process which leads to an extended lifetime of the MMO electrodes compared to other electrodes. Especially the integration of iridium to the coating provides an enhanced stability and lifetime of the electrode. Thus, the process can run smoothly without disruptions (e.g. exchange of electrodes) for a long time.
Major Applications of MMO Electrodes and Other Precious Metal-Based Electrodes:
- Chlor Alkali Electrodes
- Water Treatment Electrodes
- Ballast Water Treatment Electrodes
- Cathodic Protection Electrodes (ICCP)
- Electrodes for Copper foil production
Precious Metal Compounds for Electrode Coatings
Heraeus Precious Metals offers a broad range of precious metal compounds for electrode coatings.
If a compound of interest is not covered in the table, please contact us for further information. We are at your service!
Protective Coatings – Turbine Airfoil Coatings (Thermal Barrier Coatings)
Precious metal coatings are used as protective layers for example in the aerospace industry. Turbine airblades used in jet engines or also in turbines for electricity generation in power stations need to be made of very stable materials (mechanical stability & resistance to environmental degradation like oxidation or corrosion) to withstand extreme environments of high temperatures (around 2000 °C) and high mechanical stress (fast rotation of more than 10,000 rpm).
Turbine airblades are therefore made of so called “super alloys” which already meet requirements to withstand above mentioned conditions quite well. However, protective platinum coatings can further improve the material quality by adding enhanced protection against oxidation and corrosion. During the coating process a special platinum-aluminide composite is formed which has excellent physical properties – even surpassing the properties of pure platinum. As a result, adding platinum and thus the platinum-aluminide layer to the superalloys lead to an extended lifetime of turbine airblades. Thus, airblades can run in the engine longer before they have to be repaired or replaced.
Compounds for Protective Coatings
Heraeus Precious Metals can offer and deliver a broad range of precious metal compounds for electrolytes used for protective coatings.
If a compound of interest is not covered in the table or you are looking for new precursors to improve the quality and/or sustainability of an electrolyte, please contact us for further information. We are at your service!
Worldwide at Your Service
Heraeus Precious Metals has in-depth expertise in the world of precious metals – including Platinum, Ruthenium and Iridium. We are at your service anywhere anytime. Customers benefit from Heraeus’ global footprint of production, trading & recycling locations. Next to the main markets in China, Europe and USA, Heraeus is also able to supply customers locally in India and South Africa.