Plasma Surface Treatment

A particularly useful form of non-thermal plasma is radio frequency (RF) plasma, which excites the electrons separately from the positive nucleus, generating an equally reactive plasma while consuming a fraction of the energy. This energy-efficient plasma can then be used to treat the surface of materials, leading to greater chemical activity and lower reaction temperatures. Some uses of this treatment include the removal of oxides from metals with hydrogen ions, exposing a more pure and reactive metal core, and coating materials with an organic layer made of molecules fragmented within the plasma that can both passivate and increase the reactivity of the material. Click on the link below to see ACT’s RF plasma setup in action.

Performance Enhancement of Energetic Materials

Energetic materials are compounds that quickly, and in some cases controllably, release chemical energy in the form of heat causing a rapid expansion of gases. This class of materials is subdivided into propellants (including fuels), explosives, and pyrotechnics. There are commercial applications for energetic materials (e.g., fireworks, demolition, etc.) and a large market for propellants in military and space applications (i.e., missiles and rockets). Surface plasma treatments can increase the energy density and safety of propellants and explosives.

Surface Plasma Treatments can Enable

Rockets or missiles to sustain longer firing ranges
Explosives that penetrate deeper and have larger blast zones,
Lower mass or volume requirements
Safer manufacturing, transportation, and storage

Surface Plasma Treatment Application Spotlight

Project Goal

Improve the energy density of liquid fuels to ultimately extend the range of current weapons platforms with the need to redesign existing platforms. However, newly developed high-density hydrocarbon-based fuels often have viscosities too high to be pumped through weapons systems or cannot achieve long-term stability. An alternative solution is to add metallic particles to current fuels to increase energy density without undesirable changes to other fuel properties such as viscosity, flash point, and freezing point.

Research and Development

ACT has demonstrated more than a 10% increase in the volumetric energy density of a liquid hydrocarbon fuel by adding boron nanoparticles while simultaneously keeping a low viscosity. To accomplish this, the surface layer of boron oxide must be removed to avoid adverse effects on energy density and kinetics. A novel, RF-based non-thermal hydrogen plasma process is introduced to remove the native oxide from the boron nanoparticle surfaces. A second plasma treatment, an innovative plasma-enhanced chemical vapor deposition (PECVD) coating, immediately follows to create an organic passivation coating that prevents the re-oxidation of the reduced particles under ambient conditions. The coating can further improve nanoparticle stability in liquid fuel environments and has the potential to further improve combustion. An example of PECVD-coated and hydrogen-plasma, PECVD-coated boron is shown below (left and right, respectively). Through these RF plasma processes, more than 90% of the initial boron oxide can be removed.

For more information, click on the link below to see our 2021 publication in ACS Applied Materials and Interfaces.

Read Article

ACT is utilizing non-thermal RF plasmas to improve the energy density of liquid fuels. Increasing the energy density of liquid fuels can extend the range of current weapons platforms without the need to redesign said platforms. However, newly developed high-density hydrocarbon-based fuels often have viscosities too high to be pumped through weapons systems or cannot achieve long-term stability. An alternative solution is to add metallic particles to current fuels to increase energy density without undesirable changes to other fuel properties such as viscosity, flash point, and freezing point. ACT has demonstrated more than a 10% increase in the volumetric energy density of a liquid hydrocarbon fuel by adding boron nanoparticles while simultaneously keeping a low viscosity. To accomplish this, the surface layer of boron oxide must be removed to avoid adverse effects on energy density and kinetics. A novel, RF-based non-thermal hydrogen plasma process is introduced to remove the native oxide from the boron nanoparticle surfaces. A second plasma treatment, an innovative plasma-enhanced chemical vapor deposition (PECVD) coating, immediately follows to create an organic passivation coating that prevents the re-oxidation of the reduced particles under ambient conditions. The coating can further improve nanoparticle stability in liquid fuel environments and has the potential to further improve combustion. An example of PECVD-coated and hydrogen-plasma, PECVD-coated boron is shown below (left and right, respectively). Through these RF plasma processes, more than 90% of the initial boron oxide can be removed.