E-Thesis 241 views
Towards state of the art vacuum locks for a novel continuous PVD galvanising process / SAMUEL MINSHELL
Swansea University Author: SAMUEL MINSHELL
E-Thesis – open access under embargo until: 24th March 2026
DOI (Published version): 10.23889/SUthesis.58877
Physical Vapour Deposition (PVD) is used in various industries to create thin coatings ranging from aluminizing crisp packaging through to thin ZnO films on solar cells and glass windows providing thermochromic control . Vacuum locks are used during manufacturing to transport material into and ou...
|Supervisor:||Nicholas Lavery ; David Penney|
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Physical Vapour Deposition (PVD) is used in various industries to create thin coatings ranging from aluminizing crisp packaging through to thin ZnO films on solar cells and glass windows providing thermochromic control . Vacuum locks are used during manufacturing to transport material into and out of the coating chamber, sometimes as a continuous process.In 2012, POSCO installed a wide PVD pilot plant  and in 2017 Arcelor Mittal opened a €63 million commercial air to air coating line, therefore demonstrating the technology is commercially viable . The advantage of PVD coating over more traditional methods such as a galvanising bath is a greater control on the coating thickness, excellent corrosion resistant properties and uniform coating across the substrate. A review of patents and publications on the state-of-the-art in vacuum lock design for the PVD steel coating technology showed that air bearings had the potential for an improved design with a greater flexibility in dealing with variable strip width and thickness.A new vacuum lock for a continuous steel strip process has been designed and prototyped by using a combination of computational modelling, continuum fluid dynamics and discrete molecular models, validated against benchmarks and experimentation. Using a set pump speed (198 m3/hr) at the outlet, the lock was designed to maintain a pressure drop of -79.3kPa and would form the first of a sequence of vacuum locks ultimately reducing the vacuum level to the pressure of 0.01 Pa required within the PVD chamber.Whilst no single computational model was able to capture the entire flow regime, the continuum models were able to suggest possible pressure drops from changing outlet mass flow rates, which was used to develop the design. By using an air bearing system at the lock entrance with thin slider blocks to adjust the gap, the lock can accommodate a steel strip with a reduced or increased thickness and width.
College of Engineering