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Evaluation of the influence of Cu2O addition on electrochemical properties of LaNi5 hydrogen storage alloy DOI:10.15199/40.2018.5.1


  1. Introduction The literature review shows that the maximum limit of hydrogen storage capacity for alloys obtained on the basis of LaNi5 intermetallic compound is approx. 1.5 wt.% [10] and it is difficult to expect significant improvement in the hydrogen capacity in this group of materials. However, the basic criterion of an alloy usability as a material for the negative electrode of a hydride cell comprises not only high hydrogen solubility in the alloy crystal lattice, but also a quick transport of hydrogen atoms inside the solid phase (high diffusion coefficient) and a quick rate of the electron transition reaction (high value of exchange current density of the H2O/Hads system). The hydrogen absorbing ability and its mobility within the crystal lattice are characteristics of the material inside and to some extent they can be improved only by changing the material’s composition and structure, but the charging/discharging process kinetics can be substantially improved, primarily via proper modification of the electrode surface. The provision of catalytic properties to a hydrogen-absorbing material has a big practical importance, because on the one hand it enables drawing significant currents from the cell, and on the other hand - allows to significantly shorten the charging time. For this purpose the alloys are most frequently subject to etching in an acid [8] or microencapsulation (deposition of thin Cu, Ni, Pd, Ru, Ni-P, Co-P etc. films on the surface of particles) [13-15]. More and more frequently an alkaline solution containing a small amount of a reducing agent is used to improve catalytic properties of alloys in the process of hydrogen absorption [1]. Also the blending of hydrogen-absorbing alloy powders with certain metal oxides results in the improvement in the electrocatalytic activation of the electrode. Results of examinations presented in paper [9] show that blending a powder of AB5 type alloy (MmNi3.6Mn0.4Al0[...]

Badania odporności na ścieranie stali konstrukcyjnych i narzędziowych Mn-Cr-Mo-V

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W artykule dokonano oceny odporności na ścieranie trzech stali Mn-Cr-Mo-V o zróżnicowanym stężeniu węgla. Określono wpływ różnych wariantów obróbki cieplnej (wyżarzanie, hartowanie, hartowanie i niskie odpuszczanie) oraz zmian zachodzących w mikrostrukturze tych stali na odporność na ścieranie. Badania prowadzono w warunkach tarcia suchego, a ubytki mas próbek mierzono na drodze tarcia 3000 m i 12 000 m. Uzyskane wyniki badań porównano z wynikami otrzymanymi dla stali narzędziowej X210Cr12 i staliwa Hadfielda X110 Mn12. Stwierdzono, że stale Mn-Cr-Mo-V najmniejszą odpornością na ścieranie cechują się w stanie wyżarzonym na sferoidyt, zaś największą - w stanie zahartowanym na martenzyt. Ubytki mas badanych stali, jak również stali X210Cr12 i staliwa X110 Mn12 korelują z ich mikrostrukturą i twardością. This paper describes the evaluation of wear resistance of three Mn-Cr-Mo-V steels characterized by different carbon content. Following factors were taken into account during evaluation of the wear resistance: type and conditions of used heat treatment (annealing, quenching, quenching and low-temperature tempering) as well as microstructure development. The wear resistance of samples were investigated under dry friction conditions, and the samples’ mass-loss were calculated after 3000 m and 12 000 m of friction. Obtained results were compared to those taken for X210Cr12 tool steel and Hadfield’s X110 Mn12 cast steel. It has been found that Mn-Cr-Mo-V steels annealed for spheroidite show the lowest wear resistance, whereas after quenching for martensite the steels are characterized by the highest wear resistance. The mass-loss of the investigated Mn-Cr-Mo-V steels and X210Cr12, X110 Mn12 alloys is well correlated with their microstructure and hardness. Słowa kluczowe: stal konstrukcyjna, stal narzędziowa, obróbka cieplna, mikrostruktura, twardość, odporność na ścieranie Key words: structural steel, tool steel, heat treatment, microst[...]

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