Dimensionally stable electrodes, although being quite simple conceptually, i.e. a titanium substrate covered with a thin layer of electroactive oxides, hide plenty of complexity: each step of the manufacturing process heavily affects the final product properties and performance. The whole production process, that starts with the electrode design, followed by the actual manufacturing and ends with the quality compliance tests, requires a constant and careful support by qualified researchers. Additionally, R&D closely assists the specific, product-oriented manufacturing process, and aims to explore new opportunities to develop more efficient and durable anodes.
We have developed a profitable collaboration with the researchers of the Corrosion Engineering & Applied Electrochemistry Lab of the University of Milan, realising a valuable bridge between the industry innovation needs and academic knowledge, personnel and instrumentations.
Our current R&D interests and activities are focused mainly in three areas:
- Electrodes characterization
- Electrodes lifetime testing
- Corrosion and Passivation
There are no doubts that a deep understanding on how and why our electrodes work is an essential core skill, allowing to define what are the features and the application limits of each of the different electro-catalytic coatings. Such knowledge represents our starting point for improvement and development programs aimed at extending our electrodes’ efficiency, reliability and durability; furthermore, it gives the best tools for a solid and trustable customer experience during the delicate initial stage of the coating engineering.
The electrode manufacturing process implies multiple variables, like the coating composition (both in quality and quantitative terms), the noble metals load, the choice of the noble metals precursors, the titanium surface preparation and finishing, the decomposition temperature etc. all of these playing crucial roles in determining the final product features and performance.
Accordingly, systematic, multi-variables studies are continuously performed, aiming to assess how each of the mentioned parameters affect the performance of the final product. In this framework, various electrochemical techniques allowing to measure and compare the relevant electrochemical parameters are merged with other physical-chemical analytical methods resulting in an – as complete as possible – electrode characterisation.
Electrodes lifetime testing
A crucial factor for our customers’ satisfaction is the electrode compliance with its desired service life. Over their wide range of application fields, our electrodes face a large variety of operative conditions, some of them being characterized by an unfavorable combination of high current density and aggressive electrolytes, could potentially yield to a premature depletion of the electro-catalytic coating. As a consequence, the electrodes’ lifetime testing goes beyond a mere Quality Assurance (QA) procedure and becomes an indispensable instrument to win our customers’ trust.
Depending on the anode type and application there are standard test methods that provide globally accepted tools for the electrode lifetime determination. This is the case of the cathodic protection anodes for which the NACE standard tests methods TM0294-2016 and TM0108-2012 give plenty of details for a trustable testing.
However, for applications other than the cathodic protection there is no standard testing procedure, although the electrode lifetime at the operative conditions still remains of a fundamental value.
At Chemical Newtech, we have developed a series of internal test methods, which are able to simulate and accelerate the electrode lifetime with respect to their different operating conditions. Such tests are used for QA-QC, and as an evaluation tool in the development of alternative coatings.
Corrosion and Passivation
Most of our electrodes are made of a titanium substrate covered with a mix of metal oxides (MMO); the globally accepted choice of titanium as the better substrate material is due to its undeniable properties of high electrical conductivity, high workability and excellent corrosion resistance. Titanium corrosion resistance is provided by a protective layer of titanium oxides that naturally forms on the metallic surface (Passivation); however, in some extreme conditions – i.e. very high electrode potential – the protective layer is dissolved and titanium can experience corrosion damages.
On the other side the growth of an insulating oxide layer at the coating-substrate interface is something to be avoided, as it would hinder the current flow, resulting in a loss of the electrode efficiency. Hence, a balance between the substrate protection and an optimal conductivity is what we are seeking for.
Possible alternatives are based on the application of a protective interlayer that would hinder the interfacial oxide growth without compromising the charge transfer properties.