Method Development for Aluminium Oxide Deposition on Substrates through Combustion of Aluminium

Abstract

This study investigates the development of a new method for the deposition of aluminium oxide (Al2O3) on substrates by aluminium combustion. Although, conventional coating techniques, such as Chemical Vapor Deposition (CVD) and Physical Vapor Deposition (PVD) are well-established, they are often complex and high in energy use. The new method aims to exploit the simplicity and efficiency of aluminium combustion and its potential applications enhancing the wear resistance, thermal stability, and durability of cutting tools and other industrial components.

The study employs a dual approach using a combustion device, capable of operating in two different modes, “droplet” and “cloud flame”. The droplet mode triggers an ignition of the aluminium wire to create vaporized aluminium droplets, while the cloud flame mode continuously disperses aluminium powder through a central tube for combustion and creating a higher particle density for deposition. The main factors influencing the coating quality, such as surface preparation, choice of substrate, powder properties, process parameters, environmental conditions and curing technology, were systematically analysed.

The experimental results confirmed the formation of Al2O3 particles by energy dispersive X-ray spectroscopy (EDS), and the particle size distribution varied within 500 nm to 53 μm. The study also showed the influence of particle morphology and early solidification on the adhesion and cohesion of the coating. The “cloud flame” setup demonstrated higher particle densities but faced challenges with early particle solidification and environmental and process
based contamination.
The study indicates that while the combustion-based deposition method shows promise
for adaptability for bigger batch sizes and efficient Al2O3 coatings, further optimization is required to address issues related to particle bonding and environmental control. In order to increase the deposition quality, future studies exploring this new approach should focus on adjusting process parameters and investigating alternative combustion gases to enhance coating quality and applicability.

Popular Abstract

In the industry, especially metal cutting tool manufacturing, aluminium oxide coatings are used as a protection and surface improvement layer. This protects like varnishes protects for example wooden benches against its environment - weather and improve their durability. To apply alumina oxide, aluminium particles are burned with oxygen in the gas and fly in the gas stream against the object to be coated. Depending on various properties of the particles such as temperature, velocity and surface pressure upon impact, the particles bond with the surface of the object.

This deposition study is based on current research at the combustion physics division in Lund University and they are looking into using aluminium as an energy carrier. Energy invested to produce aluminium, can be recovered in the form of thermal and radiant energy by burning the aluminium. This energy carrier system could act as a battery by converting aluminium oxide to aluminium when electricity prices are low and burning the aluminium to create aluminium oxide and energy when electricity prices are high. The aluminium can also be transported from regions which have for example geographical advantages for renewable energy generation to regions where energy is needed and burned there to generate energy. The new addition by this study is that the released particles can also be used to coat objects.

To evaluate the feasibility of coating a surface with aluminium oxide by burning aluminium different investigations were undertaken. The particles deposited on an object’s surface, were investigated and were determined to be aluminium oxide. A particle size distribution, which shows what amount, and which sizes in particles were found on the objects surface, was found. The appearance of the particles on the surface was also evaluated and various conclusions could be drawn from them, such as too early solidification of the small particles before impact, which caused them to partially bounce off like a bullet hitting a metal wall. The bonds that the particles formed with the object or other particles were also evaluated; these were largely inadequate. Only small particles bonded with each other on the trajectory to the object. The particle density was also assessed, which shows large voids/gaps and thus makes it difficult for particles to bind together. Finally with the help of a cause-and-effect analysis suggestions for improvement were identified. This can pave the way for further development of the concept in the future and offer an alternative to the well-established methods with its higher energy efficiency, scalability and simplicity.

• author: Ostner, Paul
• supervisor: Henrik Feuk; Zhongshan Li
• organization: Production and Materials Engineering
• course: MMTM05 20241
• year: 2024
• type: H2 - Master's Degree (Two Years)
• subject: Technology and Engineering
• keywords: Aluminium oxide, Combustion, Coating, Deposition, Particle size distribution, Al2O3, SEM
• report number: LUTMDN/(TMMV-5366)/1-65/2024
• language: English
• id: 9160430
• date added to LUP: 2024-06-10 08:58:07
• date last changed: 2024-06-10 08:58:07