Chrystelle Bernard

Name of university
Tohoku University
Frontier Research Institute for Interdisciplinary Sciences
Assistant Professor
Device and Technology

Research Fields

Material Sciences, Mechanics of Polymers

Research Keywords

Cold spray process

Research Subject

Nanomechanics of polymer particles under high velocity impact

Research Outline

Cold spray process is a relatively new manufacturing process which allow to create coating on any surfaces. The process propels nano/micro sized particles at a high velocity on a substrate surface using a pressurized heated gas. Recently, the process has been successfully used to develop perfluoro-alkoxy alkane (PFA a semi-crystalline polymer) exhibiting good adhesion strength, super-hydrophobicity, and a high deposition efficiency of the particles (>95%). However, the adhesion mechanisms still remain unknown, and the impressive results (in regards of adhesion strength and deposition efficiency) obtained with this particular polymer where not equalized with other polymers such as ultra-high molecular weight polyethylene (UHMWPE). 
Therefore, it is necessary to adopt a complementary approach by combining experimental, theory, modelling, and simulation. In this study, I aim to understand 
(i) the high velocity impact of microparticles at the scale of the microstructure (size of the crystalline lamellae: some µm)
(ii) the flow dynamics in the cold spray nozzle
(iii) the particle history inside the nozzle
(iv) the adhesion between polymer/polymer and polymer/metal.