Institute of Materials and Machine Mechanics
Topic
Investigation of Laser Ablation Surface Preparation for Capacitor Discharge Stud Welding on Coated and MLI-Covered Aerospace Aluminium Structures
PhD. program
Engineering Technologies and Materials
Year of admission
2026
Name of the supervisor
Ing. Marek Gebura, PhD.
Contact:
Receiving school
Faculty of Special Technology, Alexander Dubček University of Trenčín
Annotation
This PhD thesis focuses on the experimental and analytical investigation of laser ablation as a surface preparation technique for Capacitor Discharge Stud (CCDS) welding on selected aerospace workpiece–stud material combinations in vacuum. The work will concentrate on aluminium alloy sheets representative of space structures and cryogenic or structural components, joined using alloy-matched aluminium studs and A2-50 steel studs, in configurations that are most relevant for in-orbit servicing and manufacturing.
The central objective is to develop a fundamental understanding of laser cleaning through realistic surface layers, including space-grade paints, anodized layers, and multi-layer insulation (MLI) blankets. The thesis will study how laser beam parameters (energy density, pulse duration, wavelength, scanning strategy) control coating removal, partial penetration, or modification, and how these processes affect the resulting surface microstructure, surface chemistry, and morphology (roughness, remelted zones, oxide layers, residual contaminants). Special attention will be paid to the interaction between laser ablation and layered systems such as MLI, where local melting, vaporisation, and redeposition of polymeric and metallic constituents can occur.
A key part of the work will be to link these laser-modified surface states to the behaviour of CCDS welding in vacuum. The thesis will investigate how laser-induced changes in surface morphology and chemistry influence arc initiation and stabilisation, current paths, contact resistance, and energy deposition, as well as how they affect weld pool formation and joint quality. Joint performance will be evaluated through microstructural characterisation (cross-sections, IMC distribution, defect population) and mechanical testing (tensile, shear, or bend tests as appropriate), enabling the definition of process windows where laser ablation improves or degrades CCDS weld reliability.
By systematically correlating laser ablation parameters, surface condition, and CCDS weld response under vacuum conditions, the thesis aims to establish guidelines for using laser cleaning as an enabling pre-treatment for CCDS welding on coated and MLI-covered space hardware. The results will provide a scientific basis for integrating laser-based surface preparation into future in-orbit servicing, assembly, and repair operations, where removal or tailoring of complex surface layers is a prerequisite for reliable stud welding.
The study will be backed by ROBSIM project, planned to be also a part of the proposal for APVV and ESA RPA calls.
The central objective is to develop a fundamental understanding of laser cleaning through realistic surface layers, including space-grade paints, anodized layers, and multi-layer insulation (MLI) blankets. The thesis will study how laser beam parameters (energy density, pulse duration, wavelength, scanning strategy) control coating removal, partial penetration, or modification, and how these processes affect the resulting surface microstructure, surface chemistry, and morphology (roughness, remelted zones, oxide layers, residual contaminants). Special attention will be paid to the interaction between laser ablation and layered systems such as MLI, where local melting, vaporisation, and redeposition of polymeric and metallic constituents can occur.
A key part of the work will be to link these laser-modified surface states to the behaviour of CCDS welding in vacuum. The thesis will investigate how laser-induced changes in surface morphology and chemistry influence arc initiation and stabilisation, current paths, contact resistance, and energy deposition, as well as how they affect weld pool formation and joint quality. Joint performance will be evaluated through microstructural characterisation (cross-sections, IMC distribution, defect population) and mechanical testing (tensile, shear, or bend tests as appropriate), enabling the definition of process windows where laser ablation improves or degrades CCDS weld reliability.
By systematically correlating laser ablation parameters, surface condition, and CCDS weld response under vacuum conditions, the thesis aims to establish guidelines for using laser cleaning as an enabling pre-treatment for CCDS welding on coated and MLI-covered space hardware. The results will provide a scientific basis for integrating laser-based surface preparation into future in-orbit servicing, assembly, and repair operations, where removal or tailoring of complex surface layers is a prerequisite for reliable stud welding.
The study will be backed by ROBSIM project, planned to be also a part of the proposal for APVV and ESA RPA calls.