Manufacturing and characterization of nanomaterials for low-temperature sintering and electronics thermal management applications
Licentiate thesis, 2020
In this thesis, a novel approach for nanoscale materials production was exploited to manufacture multi-elements alloyed iron nanoparticle. Using spark erosion, low carbon steel nanopowder was produced in order to tune the chemical composition of the nanoparticles in order to combine size effect with composition effect and tailor their performances. A melting depression recorder, while the sintering behaviour of the powder indicated an early activation of the diffusion at temperatures higher than 150°C. The results allow such materials to be used as a sintering aid and lower the sintering temperature of iron powders.
Secondly, graphene-coated copper nanoparticles were developed as additives for nanofluids. The nanocomposite fillers of the copper core with multilayers graphene shell were added to water as the base-fluid. The presence of the graphene coating acted as oxidation protection for the metallic particles. Besides, it was found that the presence of the graphene as a local coating on the spherical metallic nanoparticles resulted in a proportional increase in the thermal conductivity of the fluid as the temperature and the concentration of the nanoparticles increased. Such an approach was found promising in the use of graphene-coated nanoparticles as fillers for nanofluids with good heat dissipation.
Finally, graphene has been used as a three-dimensional (3D) foam structure with sintered silver nanoparticles. The sintering of the metallic particles allowed a pressure-free attachment of the high porosity and lightweight material on the back of a chip as a heat sink. The thermal properties of the graphene foam were investigated and found to reach a thermal conductivity of 319 W/mK. The addition of a layer of coating of silver on the 3D graphene foam material improved further its thermal properties with a 54% enhancement in its effective thermal conductivity. The high porosity fraction was later gradually filled with paraffin as a phase change material. As a result, the maximum temperature of the chip was proportionally lowered and delayed. Most importantly, a CFD model was developed to study the contribution of the secondary microchannels in the heat dissipation process and revealed a positive and non-negligible effect of the additional microporosity present in the case of the graphene foam structure.
multi-elements alloyed nanoparticles
phase change materials
Chalmers, Microtechnology and Nanoscience (MC2), Electronics Material and Systems Laboratory
Characterisation and melt point depression of nanosized low carbon alloyed powder produced by spark-erosion- Zehri Abdelhafid; Swathi K. Manchili; Ye Lilei; Hryha Eduard ; Nyborg Lars; Liu Johan
Graphene-coated copper nanoparticles for thermal conductivity enhancement in water-based nanofluid
2019 22nd European Microelectronics and Packaging Conference and Exhibition, EMPC 2019,; (2019)
Paper in proceedings
High Porosity and Light Weight Graphene Foam Heat Sink and Phase Change Material Container For Thermal Management- Abdelhafid Zehri, Majid Kabiri Samani, Martí Gutierrez Latorre, Andreas Nylander, Torbjörn Nilsson, Yifeng Fu, Nan Wang, Lilei Ye, Johan Liu
Nanotechnology Enhanced Sintered Steel Processing
Swedish Foundation for Strategic Research (SSF), 2016-01-01 -- 2020-12-31.
Manufacturing, Surface and Joining Technology
Metallurgy and Metallic Materials
Chalmers Materials Analysis Laboratory
Areas of Advance
Technical report MC2 - Department of Microtechnology and Nanoscience, Chalmers University of Technology: 432
Chalmers University of Technology
Opponent: Gustaf Mårtensson, Mycronic AB, Sweden