A New Pulsed Plasma Technology for Making Micron and Sub-micron Metallic Powders

Existing methods of producing micron powders for additive manufacturing (3D printing) make use of continuous flow of gas or plasma jets to atomize a metallic melt stream. These methods suffer from producing powders with a broad distribution of powder sizes resulting in low yields for small sizes and thus high cost, because of their fundamental limitations on the velocity shear and ram pressure of the CW plasma or gas jets. The high cost of the specialty powders such as Ti limits the market potential and growth of AM. We propose to replace the continuous process with a repetitively pulsed process by using our proprietary pulsed contoured-gap coaxial plasma gun to produce pulsed plasma jets. The plasma jets will have 10 times higher ram pressure and velocity shear, the key parameters in determining the particle size and the width of the size distribution in atomizing a melt stream. As a result, our proposed technique will produce smaller particles, with better sphericity, and narrower distribution of sizes peaked where we want it to be, by precision tuning the density and velocity of our pulsed plasma jets. Increasing yields reduces production costs and increases value of powders produced. Our proposed technique will also likely enable production of specialty powders not producible by other physical methods. AM is a game-changer in the 21st century, transforming the way we manufacture, given its potential for huge time savings, waste reduction and energy savings. AM can also be used to make highly complex parts which are extremely difficult or impossible to make using traditional manufacturing methods. Due to its unique properties, titanium (Ti) is a leading metal powder for AM. The market for Ti powder for AM application alone in 2017 was $155M and is growing at a compound annual growth rate (CAGR) of 25%, and expected to reach a market size of about $740M by 2024. The proposed research will also contribute to advancing the frontiers of plasma-surface (PSI) and plasma-material interactions (PMI), the nonlinear interactions of a high-momentum-density plasma flow with a liquid medium, the development of a high repetition-rate, self-switching plasma gun, and the investigation of electrode erosion rates.