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Next-generation coatings for advanced wear-resistant materials (Next-Coat)

Next-generation coatings for advanced wear-resistant materials (Next-Coat)

Experimentally-oriented PhD student position.
Position
PhD-student
Department(s)
Department of Mechanical Engineering
FTE
1,0
Date off
30/09/2020
Reference number
V35.4471

Job description

A PhD vacancy is available in the Hoefnagels group (www.tue.nl/en/research/research-groups/hoefnagels-group/) within the Mechanics of Materials section (www.tue.nl/mechmat) at the department of Mechanical Engineering at the Eindhoven University of Technology (TU/e).  The candidate will be co-supervised by Associate Professor Johan Hoefnagels at the TU/e and Assistant Professor Francesco Maresca at the University of Groningen (RUG; www.rug.nl/staff/f.maresca). This PhD project forms the experimental part of the 2-PhD Next-Coat project, in which Materials innovation institute (M2i), Tata Steel Europe, and several academic partners collaborate on the development of an advanced steel coating, e.g., for the automotive industry.

Project: Next-generation coatings for advanced wear-resistant materials (Next-Coat)

This project aims at unravelling the influence of chemistry and microstructure on the key mechanical properties of anticorrosive coatings, such as the strength, the ductility and the wear-resistance. The producers of these materials can tune the chemistry and microstructure, however with limited understanding of what controls these properties. We address this question by an integrated multi-scale experimental-modeling approach (with one experimental and one numerical PhD student), considering (i) the role played by chemistry on the nanoscale mechanisms such as dislocation plasticity and failure, and (ii) the influence of the microstructure, including the grain boundaries, on the plasticity and failure of polycrystalline coatings. The key (atomic-scale) mechanisms (dislocation glide, grain boundary mechanics, and crack propagation) governing plasticity, damage and wear in zinc-containing alloys will be identified, including the effects of chemistry, through:

  1. Cutting-edge in-situ nano-mechanical testing of individual coating constituents combined with state-of-the-art high-resolution-EBSD for full-field (residual) stress mapping, at the Multi-Scale lab at TU/e (the experimental PhD student),
  2. Molecular Dynamics simulations with state-of-the-art interatomic potentials for random alloys combined with detailed atomic-scale dislocations and grain boundaries simulations, at RUG (the numerical PhD student).

The key deformation and damage mechanisms will be experimentally studied, identified, and unraveled and subsequently incorporated in a multi-scale crystal plasticity model, which enables predictive failure simulations of ~10 micrometer-thick coatings on steel, which will again be validated experimentally. The resulting fundamental understanding will be cast in a predictive theory of strength and failure of coatings for a wide range of alloy concentrations, to guide the design of next-generation coatings with unprecedented strength, damage and wear resistance.

PhD vacancy with a focus on experimental micro- and nano-mechanics

This PhD vacancy concerns the experimental part of the project to measure, reveal and understand the nano-scale deformation and failure of Zn-based coatings in detail. The main challenge is to perform in-situ nano-mechanical testing of individual coating constituents inside the SEM including SEM-DIC (digital image correlation) to measure the evolution of the strain field at the specimen surface and to critically analyze the full-field results to unravel deformation, damage, and failure mechanisms at the nano scale. To this end, a number of state-of-the-art micro-mechanical characterization techniques will be employed and combined:

  • Nano-mechanical testing under in-situ SEM observation at very high resolution of the single crystal and grain boundary mechanics in Zn-based alloys, with full control of the crystallography and the boundary constraints which enables direct comparison with CP simulations.
    • A serious challenge lies in producing high-quality nano-tensile specimens by isolating the microscale tensile bar using an intricate focused ion beam milling procedure from a sharp   wedge made from the coating.
    • High-quality EBSD map needs to be taken from both side of the nano-tensile specimens to have a good idea of the microstructure over the complete specimen volume.
  • Advanced SEM-DIC (digital image correlation) to achieve high-quality strain fields at nano-meter strain accuracy, which requires application of a high-quality nano-scale random speckle pattern on the ultra-delicate nano-tensile specimens,
  • Measurement of both geometrically necessary and statistically stored dislocations, also near grain boundaries, by using HR-EBSD and ECCI, both techniques being state-of-the-art characterization techniques, especially when applied to HCP thin films.
  • Systematic integration of experimental validation with numerical modeling of plasticity and failure.

Research group Mechanics of Materials and its Multi-Scale lab

The Mechanics of Materials MoM section (www.tue.nl/mechmat) is globally recognized for its research on experimental analysis, theoretical understanding and predictive modelling of a range of phenomena in engineering materials at different length scales, which emerge from the physics and the mechanics of the underlying multi-phase microstructure. A systematic and integrated numerical-experimental approach is generally adopted for this purpose. This focus is closely related to intrinsic material properties (multi-scale plasticity in advanced steels, interfacial properties in laminates, thermo-mechanical fatigue in cylinder heads, etc.), the application of materials in microsystems (i.e. multi-phase functional materials, MEMS, stretchable electronics, etc.) and various systems and processes involving mechanically complex interfaces (e.g. in Systems in Package, flexible displays, electronic textiles).

The MoM section has a unique research infrastructure. Dr. Hoefnagels is the principal supervisor of the Multi-Scale Lab (https://www.tue.nl/en/research/research-labs/multiscale-lab/), which is dedicated to ‘integrated mechanical testing’, allowing for quantitative in-situ microscopic measurements during deformation and mechanical characterization within the range of 10-9-10-2 m. To this end, the Multi-Scale lab contains a range of (home-built) micro-mechanical tests & high-end microscopes (including 4´SEM, 3´EBSD, 2´EDX, 3´Profilometry, 4´Opt.Micr., 2´AFM/STM, µ-CT-scanning, 6´DIC, Micro&NanoIndentation, 3 µ-tensile stages, & 6 dedicated µ-testing stages). The Multi-Scale lab will fully available for the Next-Coat project.            
 

Job requirements

Talented, enthusiastic candidates with excellent analytical and communication skills and high grades are encouraged to apply. A MSc degree (or equivalent) in Mechanical Engineering, Materials Science, Physics or a related discipline is required, combined with a strong background in experimental micro-mechanics, microscopic characterization, mechanics of materials, and solid mechanics theory. Experience in wear, coatings, metallurgy, damage mechanics are of benefit.

Conditions of employment

  • A meaningful job in a dynamic and ambitious university with the possibility to present your work at international conferences.
  • A full-time employment for four years, with an intermediate evaluation after one year.
  • To support you during your PhD and to prepare you for the rest of your career, you will have free access to a personal development program for PhD students (PROOF program).
  • A gross monthly salary and benefits in accordance with the Collective Labor Agreement for Dutch Universities.
  • Additionally, an annual holiday allowance of 8% of the yearly salary, plus a year-end allowance of 8.3% of the annual salary.
  • A broad package of fringe benefits, including an excellent technical infrastructure, moving expenses, and savings schemes.
  • Family-friendly initiatives are in place, such as an international spouse program, and excellent on-campus children day care and sports facilities.

Information and application

More information

Do you recognize yourself in this profile and would you like to know more? Please contact Jolanda de Roo, jolanda.deroo@Mindsforinnovation.nl

For information about terms of employment, see here. Please visit https://jobs.tue.nl/en/vacancies.html to find out more about working at TU/e!

Application

We invite you to submit a complete application by using the 'apply now'-button on this page. The application should include a:

  • cover letter in which you describe your motivation and qualifications for the position.
  • detailed Curriculum Vitae, (including an overview of your experience with experimental micro-mechanics, microscopic analysis techniques, materials characterization, micro-mechanical testing, digital image correlation, damage analysis, Matlab/Python coding, FEM simulations, numerical analysis; also include your date of birth and profile picture)
  • the official transcripts of your BSc and MSc grades and a brief description of your MSc thesis.
  • list of references with full contact information (including the supervisors of your final BSc and final MSc projects)

We look forward to your application and will screen it as soon as we have received it. Screening will continue until the position has been filled.