Improving Surface Finish of Metallic Powder Bed Additive Manufactured Components by Multi-Step Electrochemical Polishing
Metallic powder bed additive manufacturing (AM) technique has been widely employed to produce near net-shape components in recent years. However, one of the major obstacles preventing the metal powder bed AM technique from being directly implemented into the production line is the poor surface finish. As an intrinsic feature of powder based AM process, the surfaces always have partially melted powders which are usually in the range of dozens of microns. As a result, the AM part has a typical surface roughness of Ra > 10 μm. In contrary, very often the engineering applications require a surface roughness of Ra < 0.5 μm. Currently, the AM parts need to be CNC machined or mechanically/manually polished to a satisfactory surface finish level. However, both CNC machining and mechanical polishing are slow and expensive processes and encounter difficulties in complex shaped parts while sometimes it is even impossible to access the undercut or internal surfaces.
This project will investigate a novel surface polishing technique based on electrochemically dissolving the micro-peaks on the rough surface. The solution based polishing method has the potential to obtain a very smooth and high gloss surface finish, enabling high productivity over a large surface area with a large quantity of components, and offering full access to all surfaces, including undercut and inner surfaces, by immersing the geometry into liquid solution. More importantly, unlike traditional electrochemical polishing processes, which often use highly corrosive or toxic chemicals, this new process uses non-toxic low concentrated mineral acids with designated additives. This ‘green’ process will be of great interest to industry.
The PhD project is jointly supervised by Dr Yingtao Tian and Dr Allan Rennie from the Department of Engineering, Lancaster University.
Applicants should ideally have a First Class undergraduate degree (or equivalent) or Upper Second Class Honours MEng in Materials Science, Chemical Engineering, Surface Engineering, Mechanical Engineering or a related discipline. You should have a keen interest in additive manufacturing and surface engineering, including materials, process development and surface characterisation. Excellent organisational, interpersonal and communication skills, along with a stated interest in interdisciplinary research, are essential.
Ideally you would have experience in a number of the below, learning the others as part of the PhD:
• Additive manufacturing
• Electrochemical processing
• Surface Engineering and metrology
• Materials characterisation
• Experimental design
• Numerical modelling
Candidates with electrochemical fabrication experiences are particularly welcome to apply. Overseas applicants should also submit IELTS results (minimum 6.5 overall and 6.0 for each element), if applicable.
Closing Date and Start Date:
We will be continuously having informal discussions with interested candidates until this position is filled.
How to apply
For further information, please contact Dr Yingtao Tian ([Email Address Removed]). Applications should be made via the Postgraduate Admissions Portal. Once you have created an account you will be able to fill in your personal details, background and upload supporting documentation.
Value of award:
The studentship will provide a successful UK/EU student with tuition fee plus a stipend of £15k/yr for 3.5 years. Non-EU students are also welcome to apply, and the studentship will only cover the tuition fee for a successful non-EU applicant. Non-EU candidates need to demonstrate sufficient financial evidence towards living cost (currently £1,015 per month according to Home Office’s Tier 4 Policy Guide) before making the formal application.
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