Characterization of Electrolessly Plated Graphite Foams with Particle Additions

With a low density and high bulk thermal conductivity, graphite foams are ideal for thermal management systems such as computer heat sinks, radiators, and heat exchangers.Previous work has shown it is possible to improve the foams performance by opening the porosity with nanoparticle additions in the foams precursor, an oil based mesophase pitch.[1] The open porosity allows more fluid, such as air or water, to pass through the foam and carry heat away.The original study, performed by Jennifer Mueller at Oak Ridge National Labs (ORNL), considered the concentrations of nanoparticle’s used.The present study looked to determine the effects of using different types of nanoparticles at a range of sizes from the nano- to micro- level.The study began by adding, respectively, silver, ceria, alumina, tungsten, and nickel to different batches of mesophase pitch at a single weight percent concentration to create graphite foams with a significant amount of continuous porosity.The pitch was foamed, carbonized, and graphitized.The final foam products were then measured in a variety of ways including thermal conductivity, permeability, and scanning electron microscope (SEM).As a side project, an electroless copper plating solution was passed through the foams to determine if a continuous and uniform copper coating could be built up.The copper coating that was eventually obtained coated the foam walls without filling the open porosity and may help to increase the foams solderability, strength, durability, and corrosion resistance.