Development of new low-cost methods for spray forming Titanium alloys is critical for many industries. Direct fabrication technologies would have an impact on many industries because of the potential for quick manufacture of parts or additive features with minimal waste. For example, in the aerospace industry the buy to fly ratios can vary from 1.5:1 for turbine blades to over 22:1 for structural members. The buy to fly ratio is the mass of material that is require to machine a part compared to the mass of material in the finished part. For compressor and ring sections, the ratio is approximately 12:1. For this family of parts, an analysis by Pratt & Whitney indicated that the buy to fly ratio could be reduced by 41% to 7:1 if cold spray could be implemented to deposit isogrids, structural ribbing, bosses, and flanges reducing the material, machining, and post processing required for the final part. This paper summarizes the results of experiments conducted in Phase I of a National Science Foundation grant to spray form Titanium alloy using the cold spray process. This paper further describes the studies performed to date in Phase II and the techniques used to decrease the porosity of the as-sprayed coating from 18% to between 2% and 5% and the post processing methods employed to further consolidate the coating and restore the as-sprayed material to near wrought properties.

Cold spray is adding another dimension to thermal spray coating processes with numerous applications that have yet to be realized. Current activities in the field of Cold Spray are rapidly moving from R&D to commercial applications in industry. To successfully commercialize the technology, cost effective, low maintenance, highly reliable, easy to operate equipment must be available and supported that is designed so that the spray processes can be controlled and repeated. With the growth of this technology there will be a demand for laboratory systems to perform applications research and development as well as high volume production machines for specific industrial applications. The recent focus of Cold Spray equipment development has been to perfect nozzles and gun assemblies, gas heaters, gas flow, powder feed, and process control. This paper describes the automated equipment that is available in the market today and presents advances in nozzle and gas heater performance as well as development of a laboratory powder feeder. This equipment will serve as the baseline for equipment that will soon be installed in industry for commercial production applications.

This report presents results of a new technology that looks promising to apply high quality corrosion resistant coatings in limited special areas. This technology could minimize or eliminate maintenance activities experienced today with existing corrosion preservation management systems. Four passivation coatings (aluminum, zinc, 85Zn- 15Al, and 55Al-45Zn) were deposited and evaluated using the Cold Spray process. The composite powders were not chemically alloyed but mixed by weight percent (powder alloyed) to prepare the composite mixture. Each coating was deposited with both nitrogen and helium gas. Deposition efficiency measurements were made for each powder/gas combination. Coatings were applied to DH-36 steel specimens and analyzed for quality of the bond line between the coating and substrate, porosity, bond strength, weight percent of metal constituents resident in the composite coatings, and integrity of the coating after 1000 hours of exposure to accelerated salt spray testing. Cold sprayed results are compared with specimens sprayed with aluminum using the flame sprayed process. Cost comparisons are made for depositing the various powders using both Cold Spray and flame spray processes.

Development of new, low-cost methods for spraying near net shapes of Titanium and Titanium alloys is critical for many industries and applications. Direct fabrication technologies would have an impact on many industries because of the potential to quickly manufacture complex parts or additive features with minimal waste. However, currently used high temperature spray technologies (Lasform, thermal spray methods) involve melting and solidification. Each new layer starts out molten, then solidifies, and must eventually cool to room temperature. This report presents results of feasibility tests for development of a new method of direct fabrication of Ti alloy parts at near-net shapes (nns) using the Cold Spray process (CSP). Several Ti-6Al-4V powders including gas atomized, plasma atomized, and hydride dehydride were tested in these experiments. Feedstock powders were characterized for particle size distribution, morphology, chemical composition, hardness, and deposition efficiency. Coatings in thicknesses of 2 mm were sprayed for evaluation of microstructure, hardness, and porosity. Thick rectangular prisms (10 mm) were sprayed for machining tensile specimens. The material properties of as sprayed and post treated coatings by heat-treating and hot isostatic pressing (HIPing) on material properties was studied. Analysis showed that after HIPing the density of sprayed Ti-6Al-4V coupons is near 100% and material properties met or exceed those of wrought material.

Cold Spray is a rapidly emerging technology with numerous applications that have not yet been realized. With the growth of this technology there will be a demand for laboratory systems to perform applications research and development as well as high volume production machines for specific industrial applications. The recent focus of Cold Spray equipment development has been to perfect nozzles and gun assemblies, gas heaters, gas flow, powder feed, and process control. This paper describes the automated equipment that is available in the market and presents some performance data. This equipment will serve as the prototype for the industrial equipment that will soon be designed and installed in industry for commercial production applications.

The rapid emergence of cold spray technology provides numerous applications that require spraying fine (<10 microns) powders, providing more uniform deposition, improved measurement of deposition efficiency and quick turn around time. The performance of high-pressure commercial powder feeders, currently available, lacks one or more of these desired performance characteristics. Further, researchers are interested in spraying many powders of different materials or particle size distributions where the powder feeder can be quickly and easily cleaned without replacing expensive consumables. The Ktech laboratory powder feeder has been designed to operate under a wide variety of carrier gas pressures (0 – 500 psig). This laboratory feeder delivers a continuous flow of powder, has a variable canister volume and is quick and easy to clean. This unique design facilitates short run research applications or higher volume extended run time dispensing. The feeder is designed to operate in either a locally or remotely through a PC based Ethernet connection. The laboratory powder feeder represents an excellent tool for high-pressure cold spray or low-pressure thermal spray processes requiring the delivery of fine powders.