Addressing Hydrogen Permeation and Embrittlement
To address the environmental impact of traditional ICE (Internal Combustion Engine) vehicles, utilising hydrogen-fuel for transport is regarded as a compelling alternative fuel to fossil fuels.
The use of hydrogen as a fuel in the automotive industry is intriguing as it can be produced and consumed with near net-zero greenhouse gas emissions, with only water vapour as a by-product. Another advantage of hydrogen fuel is that it allows for the possibility of repurposing existing engines and vehicle platforms by enriching ICE fuels with hydrogen, as opposed to a new system (i.e. Electric vehicles), reducing costs and waste. Although the advantages of hydrogen fuel technology are evident, there are still several challenges to overcome to unlock the full potential of hydrogen in the automotive industry.
One of the biggest challenges is hydrogen embrittlement within the systems. Hydrogen molecules are the smallest diatomic molecules, its small size and light weight allows for high diffusivity. They can easily travel within materials via diffusion (hydrogen permeation), furthermore, its diffusivity would further increase under high temperatures and pressure environments i.e. within a car exhaust system. This could increase the risk of permeation and leakage of hydrogen into its surroundings in the engine block and exhaust system which are usually built with aluminium, steel alloys and others.
One of the biggest challenges is hydrogen embrittlement within the systems. Hydrogen molecules are the smallest diatomic molecules, its small size and light weight allows for high diffusivity. They can easily travel within materials via diffusion (hydrogen permeation), furthermore, its diffusivity would further increase under high temperatures and pressure environments i.e. within a car exhaust system. This could increase the risk of permeation and leakage of hydrogen into its surroundings in the engine block and exhaust system which are usually built with aluminium, steel alloys and others.
As a result of these high temperature, high pressure environments, hydrogen is introduced into the materials’ structure by diffusion, causing hydrogen embrittlement. Hydrogen embrittlement can cause drastic failure as the material becomes brittle, whereby cracks are initiated by the diffusion of hydrogen into its microstructure. For example, in steel, hydrogen will initiate cracks at around 220°C and react with the cementite (Fe3C), reducing its strength significantly, shown by graph on the right.
Hydrogen diffuses into the metal’s matrix, followed by decarbonization, initiating cracks in the microstructure.
The experienced engineering team at Zircotec have developed a specialist ceramic coating that acts as a hydrogen permeation barrier for H2-ICE systems for different car components. Our H2 specialist ceramic coating can prevent hydrogen embrittlement by controlled porosity in our coating solution. This high-density coating minimises hydrogen diffusion and leakage through these surfaces, aiding the prevention of potential failures in car componentry. Another innovative solution is currently under development at Zircotec for H2-ICE that is a non-line-of-sight coating that will be capable of coating internal surfaces from engine block downstream to catalyst, providing protection from hydrogen permeation and embrittlement.
Turning theory into practice with APC 18
We are proud to play a key role in the £14.6 million Advanced Propulsion Centre (APC) UK’s Cummins – Brunel project, which aims to develop zero-emission hydrogen internal combustion engines. We are also collaborating with Dolphin N2 in the £1.6 million RE-ARMD project, where it uses hydrogen fuel in a brand-new cycle to improve efficiency and reduce creation of harmful gases during combustion. This is achieved by recycling heat produced with the recuperator which could be the future in heavy freights, agriculture, construction, marine and more.
Hydrogen is fast becoming a key solution for the future of our energy requirements, even outside of the automotive industry. Feel free to get in touch if you have a Hydrogen ICE project that could benefit from our experience and product portfolio.