| Heat transfer through interfaces affects efficient thermal management of many systems on ship. For instance, In terms of heat dissipation of electronic components, with the continuous development of automatic systems on board ship, a great number of electronic components are used in the automatic systems. The power of the electronic components continue to escalate, while their size decrease. Therefore, thermal management plays a key role in electronics cooling to maintain their proper working condition. The existence of thermal contact resistance is the bottleneck of heat dissipating for electronic components. In terms of ship waste heat recovery system, the overall efficiency of thermoelectric conversion devices is also associated with the interface heat transfer.The thermal performance of vertically aligned carbon nanotube (VACNT) arrays as thermal interface materials (TIM) was firstly studied. VACNT arrays were synthesized by chemical vapor deposition method, and then transferred by dipping in hydrofluoric acid (HF acid) solution to get a free standing VACNT array. Then the thermal performance of the VACNT array used as TIM with and without bonding was evaluated. Results show that:the overall thermal resistance of the sandwiched structure sample with 152?m VACNT array used as TIM is 174.5±13.1mm2K/W. While, the overall thermal resistance of sample with 152?m VACNT array bonded with thermal pads is 103.1±7.7 mm2K/W. Compared with two copper plates in direct contact, thermal resistance can be decreased by 74.11% and 83.46%, respectively. Heat transfer through interface can be improved with the use of VACNT array, however, the thermal resistance of the synthesized samples are still high.Liquid metal alloys (LMAs) possess high thermal conductivity and offer extremely low thermal resistance at a small bond line thickness (BLT). Therefore, LMAs are good candidates for the next generation TIMs. Then, the thermal performance of LMAs as thermal interface material was further studied. The thermal performance of pure and oxidized Ga62.5In21.5Sn16 used as TIMs were measured. Results show the overall thermal resistance of samples are 4.822±0.130 mm2K/W and 11.202±0.278mm2K/W, respectively. Compared with two copper plates in direct contact, thermal resistance can be decreased by 99.3% and 98.3%, respectively. In order to accurately determine the thermal conductivity and thermal interface material of LMAs, a new method based on laser flash method in combination with special designed samples was proposed. The thermal performance of pure and oxidized Ga62.5In21.5Sn16 were measured by this method. Results show the measured thermal conductivity are 37.047+3.781 W/(m·K) and 15.346±2.068 W/(m·K), and the corresponding thermal boundary resistance are 2.142±0.379 mm2K/W and 4.58±0.908 mm2K/W, respectively.Though, LMAs possess high thermal conductivity and offer extremely low thermal resistance at a small BLT, the degration of thermal performance due to oxidation and pumping out in practice use are the main problems. In order to reduce their fluidity and enhance the thermal performance of the oxidized LMA (OLMA), copper and graphene particles were homogeneously dispersed into the LMA. The thermal performance of the synthesized pastes was evaluated by laser flash method. Results show that:The thermal performance of the graphene-OLMA paste is low. For samples with 2.0wt% graphene-OLMA as TIM, the overall thermal contact resistance is 42.2±3.2 mm2K/W. The increased thermal contact resistance is caused by the poor wettability between LMA and graphene, which results in air pockets trapped in the graphene-OLMA paste. While, the copper-OLMA paste can enhance the thermal performance and reduced the fluidity of OLMA. In this paper 5 kinds of copper-OLMA pastes were synthesized, with the copper weight percentage of 2.5wt%,5wt%,7.5wt%,10.0wt% and 12.5wt%, thermal performance of the 5 pastes were measured. Results show with the increase of copper weight percentage, the thermal conductivity increases linearly, while the thermal boundary resistance firstly decreases then increases. Compared with OLMA the thermal conductivity of 12.5wt% copper-OLMA past increases by 153.5%, and the value is 38.907±8.689 W/(m·K); while compared with OLMA the thermal boundary resistance of 2.5wt% copper-OLMA past decreases by 74.6%, and the value is 1.164± 0.481mm2K/W.In order to study the factors affecting the interface resistance, mathematic model for predicting thermal boundary resistance at liquid metal-solid interface was established. The model expresses thermal interface resistance as a function of topography of solid surface, wettability of the liquid on rough surface, mechanics of contact at the interface, and thermal parameters of the contacting bodies. The model shows that thermal boundary resistance decreases with the improved wettability, increases with the increased surface roughness, these conclusions were verified by the experimental data. |
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