Modeling the dissolution, solidification, and mechanical response of WC-Co coating nano-microstructures

Nanoscale carbides offer good mechanical behavior in sintered WC-Co structures, but the carbides can dissolve excessively in thermal spray deposition, thereby embrittling the coating. We aim to predict the process conditions and carbide size distributions that do not lead to excessively dissolved structures, and give rise to coatings with good mechanical performance.

The initial WC-Co structures are generated both artificially and segmented from SEM-images of powder particles. Phase field method is used to simulate the in-flight WC dissolution in order to predict the conditions-WC size distributions and process temperatures- that leave the carbides intact. Subsequently, we model the solidification of these dissolved structures, in order to estimate the content of embrittling phases: W2C and M12C carbides, and binder amorphicity.

These virtually dissolved and solidified microstructures are put under simple mechanical loading tests in finite element method based micromechanical simulations, to pinpoint the role of WC size distribution and the embrittling phases. The virtual microstructures are compared to SEM-images, which are image-segmented and put under the same mechanical loading simulations.