Improved Stability and Performance of Surface-Modified Constantan Wires, by Chemical Additions and Unconventional Geometrical Structures

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At INFN-LNF, starting in 2011, we have investigated the behavior of the Constantan (Cst) alloy (Cu55Ni44Mn1; ISOTAN44) with hydrogen and/or deuterium (H2/D2) absorption and the generation of anomalous excess heat (AHE) at high temperatures (i.e. >200◦C). To further improve the intrinsic, excellent catalytic proprieties of Cst in H2 → 2H dissociation, we subjected the surface to repeated cycling of “flash” oxidation (pulsed power up to 20 kVA/g), obtaining sub-micrometric particles of mixed composition (Cst–NiOx–CuOy–CuxNiyOz) and reducing deleterious self-sintering problems with nano-materials at high temperatures. Despite the fact that insulation). Recently, we adopted the methodology of making several knots along wires (holes 150–200 μm), later coated multiple times with an iron solution. We introduced potassium into thesolution (which is known as a promoter of iron catalytic performance) and, eventually, manganese to prevent or decrease potassium evaporation. H+ electro- migration, due to large current (>2 A) flowing along the Cst wires as well as high magnetic fields at the center of the knots and on iron micro-particles (absorbing hydrogen at high temperatures) deposited inside micro-holes of Cst, is supposed to play a role in AHE. The cylindrical thick-glass wall reactor had a volume of 250 cm3; operating pressures were 0.1–3 bar; the gases used were helium (for calibration), D2, pure or mixed with xenon (which has ultra-low thermal conduction). In a difference from our previous experiments, we employed only D2 and not H2. The three wires we used were: platinum for calibration purposes and “indirect heating” of Cst wires, and Cst with 41 and 71 knots. Input power range was 10–90 W. Up to now we have observed that the AHE, measured at the external wall of the reactor, reached the largest values (over 85 W, by comparison/extrapolation with platinum under helium, isoperibolic procedure) when the highest input power (90 W) was applied to the 71-knots Cst in D2 mixed with xenon. Further work is necessary to evaluate the effects of: I versus J, numbers of knots, gas mixtures, temperature (including electron emission from SrO: inspired by Iwamura’s experiments, and the Richardson law). results with thin, long wires (Φ = 200 μm, l = 100 cm) were generally positive and excess power (10–20%) was frequently recorded (5–10 W at 50 W input), reproducibility remained unsatisfactory. Later, we realized that iron impurities (up to 1% in the old, pre-1970 batch of Cst) enhanced AHE generation, especially at T > 500◦C. Since 2014, we added Fe(NO3)3 solutions both to the Cst sub-micrometric surfaces (during flash oxidation process),and to borosilicate glass sheaths (SIGI-Fabier; micrometric fibers, previously wetted-dried with Sr(NO3)2 solution) where wires were inserted (as electrical