For Aluminum cold-sprayed coatings was found that increasing the gas temperature improves DE and ascent the coating porosity.
Are there any ideas or research on this topic available? I would be glad if you share your thoughts about it with me.
My thought is that heated particles shrink during the cooling process, and pores appear.
You think absolutely correctly: the higher the temperature of the particles, the greater their shrinkage, and hence the porosity of the coating. However, a simple decrease in the particle temperature does not solve this problem, since when spraying cold particles, two new, more serious problems appear.
The first problem is that deformation of cold particles requires more kinetic energy than deformation of hot particles (a higher speed is required), in addition, the degree of deformation of cold particles is less, and work hardening is greater.
The second problem is the formation of metallic bonds between particles in the coating: the lower the temperature of the particles, the less bonds are formed. So it turns out that it is impossible to do without heating the particles, and the problem with shrinkage has to be solved in other ways.
One of these methods used in the cold spray technique is the use of mixtures of metal and abrasive powders such as aluminum-corundum.
Hi Dr Aleksandr Elkin . I hope the following link could help you: https://core.ac.uk/download/pdf/223117247.pdf
Also, see the following link: http://yadda.icm.edu.pl/yadda/element/bwmeta1.element.baztech-429fe5d9-8f42-443a-8a5d-b850b919f4db/c/10.24425123436.pdf
Kindly, see also the following link: Article A Finite Elements Study on Porosity Creation Mechanisms in C...
Check https://www.researchgate.net/publication/267904241_Effects_of_Gas_Temperature_Gas_Pressure_and_Particle_Characteristics_On_Cold_Sprayed_Pure_Titanium_Coatings
Also check https://www.sciencedirect.com/science/article/abs/pii/S0257897216300585
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