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In this work, we study the thermal stability of a hydrothermally treated stainless steel (SS) selective solar absorber by annealing in air in a temperature range between 300 °C and 700 °C for a soaking time of 2 h. Thermal stability testing in the presence of air is critical if the vacuum is breached. Therefore, the SS was characterized by X-ray diffraction (XRD), mechanical, and optical techniques. The XRD analysis shows that the grain size of the as-treated absorber is 67 nm, whereas those of the annealed absorbers were found to be in the range between 66 and 38 nm. The phase of the as-treated and annealed SS was further identified by XRD as Fe2O3. The EDS result shows that the elemental components of the SS were C, Cr, Fe, and O. The strain (ε) and stress (σ) calculated for the as-treated absorber are 1.2 × 10−1 and −2.9 GPa, whereas the annealed absorbers are found in the range of 4.4 × 10−1 to 5.2 × 10−1 and −121.6 to −103.2 GPa, respectively, at 300–700 °C. The as-treated SS absorbers exhibit a good spectra selectivity of 0.938/0.431 = 2.176, which compares with 0.941/0.403 = 2.335 after being annealed at 300 °C and 0.884/0.179 = 4.939 after being annealed at 700 °C. These results indicate a small improvement in absorptivity (0.941) and emissivity (0.403) after annealing at 300 °C, followed by a significant decrease after annealing at 700 °C. The obtained analysis confirms that the annealed SS absorber exhibits excellent selectivity and is suitable to withstand any thermal condition (≤700 °C) in air. Thus, using a cost-effective approach as demonstrated in this study, the as-treated and annealed SS absorber could be used for photo-thermal conversion applications. [ABSTRACT FROM AUTHOR]

• The elastic recoil detection analysis shows 41 at.% of H absorbed in CP-Ti. • The amount of hydrogen absorbed by Ti-6Al-4V alloy was 31 at.%. • Pd layer improved the hydrogen absorption capacity of Ti-6Al-4V alloy to 36 at.%. • The H depth profile shows the highest diffusion depth in CP-Ti. Hydrogen storage capacity of CP-Ti, Ti-6Al-4V alloy, and Ti-6Al-4V alloy coated with a thin Pd layer was investigated. All samples were hydrogenated at 550 °C for 3 h in 15% hydrogen and 85% argon gas mixture. The hydrogen content and its depth profile were investigated using elastic recoil detection analysis (ERDA) while the X-ray diffraction was used for phase analysis. The highest average content of hydrogen of (41 ± 60) at.% was absorbed in CP-Ti while (31 ± 4) at.% H was determined in Ti-6Al-4V alloy. The presence of a thin Pd catalytic layer improved the hydrogen absorption of alloy to (36 ± 3) at.% H. With the beam energy of 3 MeV, H was profiled up to (4520 ± 410) × 1015 atoms/cm2, (3250 ± 300) × 1015 atoms/cm2 and (3950 ± 360) × 1015 atoms/cm2 in CP-Ti, Ti-6Al-4V alloy and in the coated system respectively. The TiH 2 hydrides were found in all three systems in addition to Pd 3 Ti phase in the Pd/Ti-6Al-4V coated system. [ABSTRACT FROM AUTHOR]

Nanostructured thin silicon-based films have been deposited using the hot-wire chemical vapour deposition (HWCVD) technique at the University of the Western Cape. A variety of techniques including optical and infrared spectroscopy, Raman scattering spectroscopy, X-rays diffraction (XRD) and transmission electron microscopy (TEM) have been used for characterisation of the films. The electrical measurements show that the films have good values of photoresponse, and the photocurrent remains stable after several hours of light soaking. This contribution will discuss the characteristics of the hydrogenated nanocrystalline silicon thin films deposited using increased process chamber pressure at a fixed hydrogen dilution ratio in monosilane gas. [ABSTRACT FROM AUTHOR]

The effect of naturally occurring oxide and oxidised layers formed by ion implantation and thermal oxidation on hydrogen absorption was investigated in Ti-6Al-4V alloy samples as a possible candidate for hydrogen storage. The samples were implanted with two different oxygen fluences (1.5 × 10 17 and 3.0 × 10 17 ions/cm 2 ) at room temperature and 550 °C, and comparison was made with thermally oxidised samples at a temperature of 550 °C for 2 h. All samples were afterwards hydrogenated at 550 °C for 2 h. The elastic recoil detection analysis show that approx.14 at.% H was absorbed in as-received and thermally oxidised samples. The native oxide layer and the oxidised layer formed by thermal oxidation enhanced the absorption of hydrogen regardless of their different thickness and stoichiometry. The amount of hydrogen, however, was significantly lower in implanted samples, approx. 3–5 at.%, suggesting that oxygen ions implanted in alloy prevent hydrogen absorption. It was found that the average amount of absorbed hydrogen within the projected depth was reduced due to implantation of oxygen ions regardless of their fluences and implantation temperature. The hydrides were not determined in any of investigated samples while the surface hardness of all samples increases after hydrogenation although to different extent. [ABSTRACT FROM AUTHOR]