Understanding the perfect powder
Composite materials have a large role to play in the application of coatings. Thermal spraying gives a material strengthening properties and heat resistance capabilities. This process involves injecting powders at enormous velocity and temperature into a flame jet and propelling them in a stream of gas onto a substrate. Here, the particles flatten onto the surface material, bond and solidify, thus imparting their intended characteristics. As exciting as it sounds, much of the process is based on the theoretical understanding of specific powder properties and on physico-chemical principles. While theory is important, an EC funded project NANOSPRAYING investigated means of testing through extensive, tightly controlled experiments. This was to further develop and characterise thermal spraying powders created from agglomerated nanocrystals. To do so, coatings were tested using X-ray diffraction (XRD) and scanning electron microscopy (SEM) investigations. With these, the characterisation of microstructural properties was made, and this resulted in the key development of important metallurgical principles that can be used in thermal spraying. The data accumulated in this research promises to bear fruit, specifically when associated with similar research from related projects. Moreover, since the research confirmed that the nanostructures achieved using thermal spraying have better performance ratios than conventional coatings, considerable breakthroughs are expected. Since so many industries use composites, in particular for surface quality improvement, this process, along with the understanding of powder performances, is sure to have enormous impact.
