Grant: Research Tools and Instruments - Category 1 (<$150,000)

Cold spray (CS) is a promising coating technology at relatively low temperatures. The main differences between the CS and thermal spray processes are in powder velocity and inert gas temperature. The high impact of supersonic particles in the CS process generates local favorable compressive residual stresses where low gas temperature minimizes or eliminates oxidation, evaporation, melting and gas release. However, the solid state bonding mechanism limits the range of spraying materials into ductile material, reduces the structural strength of the bond and hardens the sprayed material. In addition, high cost of helium gas required for generating supersonic velocity limits CS applications. On the other hand, laser cladding with lower operational cost allow for coating/cladding of a much wider range of materials including titanium, tool steels, and aluminum alloys. However, the thermal-based process of laser cladding generates detrimental residual stress, solidification shrinkage, and unwanted intermetallic phases. In the proposed research, the requested CS infrastructure will be integrated with the existing fiber laser and positioning devices to a single novel laser-assisted cold deposition system with working temperature range lower than melting temperature and higher than the conventional CS. This one of a kind system will remove high operational cost by using nitrogen or argon in CS, maintains sub-melting temperature for deposition to overcome fusion related deficiencies, provide stronger bonds than CS through laser-assisted bonding, and allows harder materials to be deposited at the enhanced temperature range. The requested infrastructure will also be utilized as a conventional CS system to develop a novel technique to stabilize and control vaporization and porosity formation in laser lap welding of coated steels. CS coating of thin layer of material with high melting temperature to the faying surface region will increase the boiling point of the liquid alloy produced by added and coat material thus lowering the coat material vaporization. The integrated system creates a unique opportunity to enable new research direction in additive manufacturing, structural durability, and material joining with benefits to many industrial applications.