The present disclosure relates to coating metallic powder particles in general, and to processes for coating metallic powder particles with silicon in particular.
Aluminum alloy materials are widely used in many areas including the aerospace industry for their light weight structural properties and in heat transfer products due to high thermal conductivity. Additive manufacturing of aluminum alloy powders, in particular, via laser based additive processes, has drawn increasing attention. A significant challenge in the laser additive manufacturing of certain alloy powders (e.g., certain aluminum alloy powders) is the high degree to which energy in the form of light waves within a laser beam are reflected away from the alloy powder. As a result of the reflectance, the energy of the reflected light does not appreciably contribute to the additive process. In some instances, it may not be possible to sufficiently increase the intensity of existing laser equipment to overcome the reflectance issue. Even in those instances where the laser intensity can be increased, such a practice can create new detrimental issues; e.g., a higher intensity laser can overheat the powder and cause the powder particles to “ball up” and consequently create a non-uniform deposition layer. Also as a result of the reflectance, present additive manufacturing processes are sometimes limited to certain types of materials. With respect to aluminum alloys, for example, additive manufacturing processes are today typically limited to cast aluminum alloy compositions. These cast aluminum alloy compositions have low reflectance properties that allow them to be used in additive processes, but possess undesirable mechanical and thermal properties.
In addition, alloy powders adsorbed with water moisture can cause significant quality issues of the deposits made by additive manufacturing processes. These issues include porosity, cracks, and blisters.
It would be beneficial to resolve the aforesaid issues and thereby improve additive manufacturing processes and make it possible to additively manufacture certain alloy powders, including additional types of aluminum alloy compositions.