Vacuum Arc Evaporated Chlor-Alkali Electrode Coating
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Solution Overview
Problem
Existing electrode coatings for chlor-alkali electrolysis cells contain substrate components and non-oxidized metals, which can lead to higher cell voltages, making the process less economical.
Innovation Solution
A method for substrate coating using vacuum arc evaporation in a vacuum chamber, where a substrate is cleaned, an intermediate layer is applied, and a pure metal oxide coating is formed by passing metals like ruthenium, iridium, or titanium with pulsed oxygen, ensuring the coating is free of substrate components and non-oxidized metals, with a surface temperature between 150 °C and 400 °C to enhance the reaction and deposition process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional coating methods (spraying, dipping, mechanical deposition) are used, then the coating process is simple and economical, but the coating contains substrate components and non-oxidized metals leading to higher cell voltages
Solution Approach 1:
The coating process is divided into distinct segments: substrate preparation, intermediate layer deposition, and final catalytic layer deposition. Each segment serves a specific function - the intermediate layer acts as a barrier to prevent substrate component migration, while the final layer provides catalytic activity. This segmentation enables high coating purity without requiring overly complex integrated processes.
Solution Approach 2:
An intermediate layer is introduced as a mediator between the substrate and the catalytic coating. This intermediate layer serves multiple functions: it prevents migration of substrate components into the coating, provides a suitable surface for catalytic layer deposition, and maintains coating integrity. The use of this intermediary layer is key to achieving high purity coatings while maintaining process feasibility.
2Manufacturing precision
If vacuum arc evaporation with intermediate layer and oxygen supply is used, then a pure metal oxide coating free of substrate components is achieved, but the process complexity and equipment requirements increase
Solution Approach 1:
The process utilizes controlled changes in vacuum pressure and oxygen partial pressure to achieve desired coating properties. By carefully adjusting these parameters during deposition, the process forms a pure metal oxide coating without substrate contamination. The temperature is also controlled within specific ranges (150-400°C) to optimize oxidation and deposition. These parameter changes enable high purity coatings while using established vacuum technology.
Solution Approach 2:
The entire coating process is conducted in a vacuum environment, which serves as an inert atmosphere preventing unwanted chemical reactions and contamination. Oxygen is then introduced in controlled amounts during the deposition process to form metal oxides. This controlled inert environment is essential for achieving coating purity while using standard vacuum deposition equipment.
3Productivity
If the coating contains substrate components, then the manufacturing process is simpler, but the cell voltage increases making operation less economical
Solution Approach 1:
The intermediate layer acts as a protective mediator that prevents substrate components from migrating into the catalytic coating. This barrier layer ensures that the final coating consists only of the desired metal oxide components without contamination from substrate materials. The result is a coating with precise compositional control that optimizes electrochemical performance and reduces cell voltage.
Solution Approach 2:
Oxygen is supplied during the coating process to accelerate the formation of metal oxides. This controlled oxidation ensures complete conversion of metal components to their oxide forms, preventing the presence of non-oxidized metals in the final coating. The use of oxygen as a strong oxidant during deposition, rather than relying on post-deposition oxidation, ensures thorough oxidation and optimal coating composition for reduced cell voltage.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method results in a coating that significantly reduces cell voltage by preventing substrate component migration and achieving a pure metal oxide layer, leading to more economical operation of electrolysis cells.
Implementation Method 1
sealing and evacuating the vacuum chamber
Implementation Method 2
cleaning the substrate by introducing a gaseous reducing agent into the vacuum chamber
Implementation Method 3
applying an intermediate layer by vacuum arc evaporation
Implementation Method 4
applying a coating by vacuum arc evaporation
Implementation Method 5
oxygen is supplied throughout the coating process
Implementation Method 6
setting the vacuum chamber to a temperature of 150°C to 400°C
Data Source
Figure 1
AI summary
Substrate coating on one or more sides comprising catalytically active material producible by a method comprising material deposition under vacuum in a vacuum chamber, wherein the following steps are run through: (a) loading the vacuum chamber with at least one substrate, (b) closing and evacuating the vacuum chamber, (c) substrate cleaning by introducing a gaseous reducing agent into the vacuum chamber, (d) removing the gaseous reducing agent, (e) applying an intermediate layer by means of vacuum arc evaporation, wherein a substrate comprising the same or similar material is introduced into the vacuum chamber, (f) setting the vacuum chamber to a temperature of 150°C to 400°C, (g) applying a coating by means of vacuum arc evaporation, wherein at least one metal taken from the group ruthenium, iridium, titanium and mixtures thereof is introduced into the vacuum chamber, and oxygen is supplied over the entire coating time, (h) in a last step the vacuum chamber is flooded again and the coated substrate is removed from the chamber, wherein the abovementioned steps and transitions from one step to the respective next step are carried out in the vacuum at different pressures, if appropriate, which are set by means of a protective gas, characterized in that at least 99% of the substrate coating on one or more sides is kept free of constituents originally contained in the substrate itself, wherein at least 99% of the coating applied on the intermediate layer is kept free of non-oxidized metals.