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H2020-ICT-2014-1 ERC-CoG-2014 CapTherPV, 647596 Aluminium doped zinc oxide (AZO) films were grown by Atomic Layer Deposition (ALD) on yellow Kapton and transparent Kapton (type CS) substrates for large area flexible transparent thermoelectric applications, which performance relies on the thermoelectric properties of the transparent AZO films. Therefore, their adhesion to Kapton, environmental and bending stability were accessed. Plasma treatment on Kapton substrates improved films adhesion, reduced cracks formation, and enhanced electrical resistance stability over time, of importance for long term thermoelectric applications in external environment. While exposure to UV light intensity caused the films electrical resistance to vary, and therefore their maximum power density outputs (0.3–0.4 mW/cm3) for a constant temperature difference (∼10 °C), humidity exposure and consecutive bending up to a curvature radius above the critical one (∼18 mm) not. Testing whether the films can benefit from encapsulation revealed that this can provide extra bending stability and prevent contacts deterioration in the long term. publishersversion published

This paper reports the influence of applied sintering process – pulsed electric current sintering (PECS) and hot isostatic pressing (HIP) – on the microstructure and mechanical properties of Cu–Cu 2 O composites. In PECS fine-grained structure was obtained while in HIPing the grain growth was more noticeable, mostly due to the longer process time. The studies also showed that Cu 2 O-phase distributed in Cu-matrix increased microhardness; at a fixed grains size Cu–Cu 2 O structure had higher hardness than Cu so that 20% higher microhardness was obtained when Cu 2 O was doubled from 19.1 to 37.2 vol%. At best, 99.1% density with 690 nm grain size and 1.35 GPa hardness were achieved by PECS whereas by HIP the same density with 1860 nm grain size gave 1.02 GPa hardness. The grain growth and the effect of second phase clustering on the grain growth were evaluated experimentally.

In this paper pulsed electric current sintering (PECS) is applied for submicron-sized copper (sm-Cu) based composite-powders aiming to produce MMC’s with higher strength and better temperature stability than reference sm-Cu. Incorporation of cuprite (Cu2O), alumina (Al2O3), titaniumdiboride (TiB2) and nano- and submicronsized diamonds (ND’s and SMD’s) improved noticeably the room temperature mechanical properties and the high-temperature stability of copper the effects becoming more noticeable with smaller dispersion size and higher amount of reinforcement. The hardness increment was at highest, when using ND’s or Al2O3. E.g., the microhardness for the reference sm-Cu sample and Cu with 3 vol.% ND’s, 6 vol.% ND’s and 2.5 vol.% Al2O3 were 1.02, 1.43, 1.77 and 1.58 GPa, respectively. Similar trend was noted also in the case of thermal stability and CTE. The study shows that Cu-ND, Cu-SMD and Cu-Cu2O are suitable for use at moderate temperatures around 623 - 673 K, whereas Cu-Al2O3 and Cu-TiB2 are suitable above 1023 K. In conclusion, PECS is suitable method to produce high quality Cu-composites having superior thermal and mechanical properties compared to those of sm-Cu.

In this work, the influences of the microstructure on the mechanical and thermal properties of pulsed electric currentsintered (PECS) Cu-Al2O3 composites are investigated. The process parameters were optimized for four different grades ofcomposite powders to obtain dense samples (98-99.6%T.D.). Higher hardness and better thermal stability were attained tothe samples compacted from commercial internally oxidized (IO) powders than to the compacts made from the chemicallysynthesised experimental powders. This difference was attributed to the distribution and size of Al2O3-particles in the twotypes of composites. The CTE values of all the compacts were between 17 and 20 x 10-6K-1 (370-770 K). The results showthat PECS can be used to produce dense high quality Cu-Al2O3 composites.