Plasma-Enhanced Chemical Vapor Deposition (PECVD) Coatings

Advanced Cooling Technologies, Inc. has utilized the plasma enhanced chemical vapor deposition (PECVD) technique to produce nanometer thin coatings to control the surface chemistry of solid substrates and enable the wetting characteristics to be customized.  The PECVD coating method utilizes a plasma to deeply fragment organic precursor molecules, which subsequently deposit onto solid substrates within the reaction chamber, such as nanoparticles.  The resultant coating exhibits similar physical properties to the precursor, thus enabling the properties of the coating to be tailored by choosing a precursor with the desired properties.

Figure 1.  Plasma Enhanced Chemical Vapor Deposition (PECVD) reactor for depositing uniform coatings that encapsulate metallic nanoparticles, thereby producing a stabilization layer around the nanoparticle that eliminates agglomeration.

Figure 1. Plasma Enhanced Chemical Vapor Deposition (PECVD) reactor for depositing uniform coatings that encapsulate metallic nanoparticles, thereby producing a stabilization layer around the nanoparticle that eliminates agglomeration.

Dry metallic nanoparticles are added to the PECVD chamber where a plasma glow discharge deeply fragments volatile precursor moleules.  These molecule fragments react on the solid surfaces within the reaction chamber, such as the surface of the nanoparticle, creating a coating that encapsulates the nanoparticle that mimics the chemistry of the voltaile organic precursor.  The coating thickness is controllable by adjusting the residence time within the reactor. By selecting the correct organic precursor, such as IPA, toluene, or perfluorodecaline, the wettability of a silicon wafer (left in the figure below) and copper oxide nanoparticles (right in the figure below) can be changed; see Figure 2.

Figure 2.  The surface chemistry of the coated nanoparticle mimics the chemistry of the precursor used during the deposition process as shown by the increasing water contact with increasing hydrophobicity of the organic precursor.

Figure 2. The surface chemistry of the coated nanoparticle mimics the chemistry of the precursor used during the deposition process as shown by the increasing water contact with increasing hydrophobicity of the organic precursor.

ACT has utilized this technique to stabilize nanoparticles dispersed in oil-based fluids for improved thermal conductivity, which has demonstrated a 4.5% improvement in thermal conductivity of polyester based turbine engine oil at 0.8% by volume addition of stabilized CuO nanoparticles.

Additionally, ACT has used this technique to stabilize aluminum nanoparticles dispersed in RP-2 fuel to prevent agglomeration and oxidation.  This prevents oxidation of the aluminum nanoparticles, and enhances fuel combustion by addition of the aluminum nanoparticles.  The coated nanoparticles had the following benefits:

  • 9% improvement of the energy density of RP-2 fuel at 3.0% addition of stabilized aluminum nanoparticles
  • 17% improvement in thermal conductivity of the RP-2 fuel at 3.0% by volume addition of stabilized aluminum nanoparticles
  • Stable suspension over a five month storage period

If you are interested in learning more about the PECVD coating method and our capabilities, please contact ACT today.