| 1. |
- Wang, Nan, et al.
(författare)
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Vertically Aligned Graphene-based Thermal Interface Material with High Thermal Conductivity
- 2018
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Ingår i: THERMINIC 2018 - 24th International Workshop on Thermal Investigations of ICs and Systems, Proceedings. - 9781538667590 ; , s. 285-288
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Konferensbidrag (refereegranskat)abstract
- High density packaging in combination with increased transistor integration inevitably leads to challenging power densities in terms of thermal management. Here, a novel highly thermal conductive and lightweight graphene based thermal interface materials (GT) was developed for thermal management in power devices. Composed by vertically graphene structures, GTs provide a continuous high thermal conductivity phase along the path of thermal transport, which lead to outstanding thermal properties. The highest through-plane thermal conductivity GTs reaches to 1000 W/mK, which is orders of magnitude higher than conventional TIMs, and even outperforms the pure indium by over ten times. In addition, a thin layer of indium metal that coated on the surface of GTs can easily form alloys with many other metals at a relatively low reflow temperature. Therefore, GTs, as an excellent TIM, can provide complete physical contact between two surfaces with minimized the contact resistance. The measured total thermal resistance and effective thermal conductivity by using 300 mu m thick GTs as TIM between two copper blocks reaches to similar to 3.7 Kmm(2)/W and similar to 90 W/mK, respectively. Such values are significantly higher than the randomly dispersed composites presented above, and show even better thermal performance than pure indium bonding. In addition, GTs has more advantages than pure indium bonding, including low weight (density < 2 g/cm(3)), low complexity during assembly and maintainability. The resulting GTs thus opens new opportunities for addressing large heat dissipation issues in form-factor driven electronics and other high power driven systems.
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| 2. |
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| 3. |
- Li, Shilei, 1982, et al.
(författare)
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Evaluation of hardening behaviors in ion-irradiated Fe–9Cr and Fe–20Cr alloys by nanoindentation technique
- 2016
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115. ; 478, s. 50-56
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Tidskriftsartikel (refereegranskat)abstract
- The ion irradiation hardening behaviors of Fee9 wt% Cr and Fee20 wt% Cr model alloys were investigatedby nanoindentation technique. The specimens were irradiated with 3 MeV Fe11þ ions at roomtemperature up to 1 and 5 dpa for Fee9Cr alloy and 1 and 2.5 for Fee20Cr alloy. The ratio of averagehardness in the same depth of irradiated and unirradiated (Hirr. av/Hunirr. av) was used to determine thecritical indentation depth hcrit to eliminate the softer substrate effect. The NixeGao model was used toexplain the indentation size effect. Irradiation hardening is clearly observed in both Fee9Cr alloy and Fee20Cr alloy after ion irradiation. The differences of ISE and irradiation hardening behaviors between Fee9Cr and Fee20Cr alloys are considered to be due to their different microstructures and microstructuralevolution under ion irradiation.
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| 4. |
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| 5. |
- Nkansah, Amos, et al.
(författare)
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Reliability study on high thermally conductive graphene film as heat spreader in electronics cooling applications
- 2018
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Ingår i: IMAPS Nordic Annual Conference, NordPack 2018. ; 2018, s. 126-130
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Konferensbidrag (refereegranskat)abstract
- ―Graphene films (GFs) were fabricated and can be applied for dissipating heat from electronics such as portable electronics, laptops, light emitting diodes (LEDs) and other power electronics. These GFs are capable of transporting heat from electronic components. Due to its high thermal conductivity, these GFs are capable to transfer the heat efficiently from electronic component to the heat spreader or heat sink. The cooling failure of the GFs may lead to irreversible damage to the electronic system, hence it is necessary to investigate the long-term reliability of the film under certain harsh conditions. To evaluate the reliability of the GFs, the thermal cycles and moisture test are performed. The effect of temperature cycling (500 cycle) is tested by using an environmental oven with extreme temperatures. The effect of moisture penetration of the GFs is tested for 1024 hours. The thermal conductivity after these two test conditions does not change too much comparing to material before subjecting to test. The electrical conductivity value under the temperature cycling declined by 30% after 500 cycles and that of moisture test was improved by 20%. The result shows that the thermal conductivity of the GFs is quite stable under temperature cycle (500 cycles) and moisture test (1024 hours).
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| 6. |
- Zhao, Dandan, et al.
(författare)
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Investigation of ion irradiation hardening behaviors of tempered and long-term thermal aged T92 steel
- 2018
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Ingår i: Journal of Nuclear Materials. - : Elsevier BV. - 0022-3115. ; 511, s. 191-199
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Tidskriftsartikel (refereegranskat)abstract
- 9Cr ferritic/martensitic steels are promising materials for in-core components in advanced Gen-IV reactors. In these applications, their long-term microstructural stability under thermal exposure and resistance to neutron irradiation are essential. Tempered (unaged) and long-term thermal aged T92 samples were used to evaluate the effects of thermal aging and ion irradiation on the microstructure and micromechanical properties of the steel. Both the tempered and aged samples were irradiated with 3 MeV Fe11+ions to 0.25, 0.50, 1.00 and 5.00 dpa at room temperature. Using the nanoindentation technique, the irradiation hardening behaviors of T92 steel were investigated. The irradiation hardening effect was observed in both the tempered and aged T92 samples. To eliminate the soft substrate effect, the critical indentation depth was determined using the ratio of the average hardness of irradiated and unirradiated samples at the same depth. Under the same irradiation conditions, the macroscopic hardness values of the aged T92 samples after irradiation were lower than those of the tempered samples. The irradiation hardening effect was more significant in the aged T92 due to the decreased dislocation density and the coarsened martensitic lath after long-term thermal aging.
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| 7. |
- Zhao, Dandan, et al.
(författare)
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Proton irradiation induced defects in T92 steels: An investigation by TEM and positron annihilation spectroscopy
- 2019
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Ingår i: Nuclear Instruments and Methods in Physics Research, Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 442, s. 59-66
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Tidskriftsartikel (refereegranskat)abstract
- In order to investigate proton irradiation damage on ferritic/martensitic T92 steels, both the unaged and aged (650 °C for 15,000 h) T92 steels were irradiated with 250 keV protons to 0.01, 0.05 and 0.20 dpa at room temperature due to the lower dose rate of protons compared with heavy-ions. The microstructural evolution induced by thermal aging and proton irradiation was studied by transmission electron microscopy and positron annihilation spectroscopy, and the corresponding micromechanical property changes were investigated by nano-indentation. After 0.20 dpa proton irradiation, the dominant irradiation-induced dislocation loops were a0100 type loops for both the unaged and aged samples. The dislocation-type defects in the aged T92 sample were larger in size and higher in number density, compared with those in the unaged samples. Less vacancy-type defects induced by protons were detected in the aged than the unaged T92 samples under the same irradiation conditions. The higher number density of dislocation-type defects led to more severe irradiation hardening in the aged T92 samples.
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| 9. |
- Andersson, Cristina, 1969, et al.
(författare)
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Low Cycle fatigue of lead-free solders
- 2001
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Ingår i: The Fourth International Symposium on Electronic Packaging Technology. ; , s. 462-470
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Konferensbidrag (refereegranskat)
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| 10. |
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