• MATERIALS

    Preparation and adsorption properties of mixed zinc-calcium phosphates

    Machines. Technologies. Materials., Vol. 17 (2023), Issue 8, pg(s) 337-338

    Here we present data on the preparation and adsorption properties of mixed zinc-calcium phosphates in aqueous dispersions. The phosphates were prepared by co-precipitation from aqueous solutions followed by autoclaving. The effects of various Ca/Zn initial molar ratios and the type of Ca- and Zn-precursor salts (chlorides and acetates) on the structure, morphology and adsorption properties of the obtained phosphates were investigated. Preliminary data on the adsorption of methylene blue indicated that the as obtained mixed zinccalcium phosphates are promising candidates for application as adsorbents.

  • The influence of Zn on the corrosion behaviour of amorphous and nanosized rapidly solidified (Al75Cu17Mg8)100-хZnx alloys and their crystalline analogues

    Materials Science. Non-Equilibrium Phase Transformations., Vol. 6 (2020), Issue 3, pg(s) 73-76

    The influence of Zn on the corrosion behavior of amorphous and nanosized rapidly solidified aluminum alloys (Al75Cu17Mg8)100-xZnx (x = 0; 1; 3) at. % and their crystalline analogues was studied. Data were obtained for resistance of basic and rapidly solidified aluminum alloys (Al75Cu17Mg8)100-xZnx (x = 0; 1; 3) at. % to uniform corrosion. It has been found that increasing the percentage of zinc increases the corrosion rate of both base alloys and rapidly solidified ribbons with similar composition. Pitting and intergranular corrosion tests have been performed. The parameters affected area, pitting density and pitting size were evaluated. An XRD analysis of the separated corrosion products was performed. It was found that the chemical composition, and not the amorphous microstructure of the ribbons, was of leading importance for the course of the corrosion process in the studied rapidly solidified ribbons (Al75Cu17Mg8)100-xZnx and base alloys.

  • CONSERVING OF THE RESOURCES

    Modelling Fe, Zn and Mn availability in soils of eastern Croatia

    Mechanization in agriculture & Conserving of the resources, Vol. 66 (2020), Issue 2, pg(s) 77-80

    Iron (Fe), zinc (Zn) and manganese (Mn) are essential microelements with plant available fraction in soil, depending significantly on soil pH and soil organic matter (SOM), which is important for crop growth. The aim of this paper is to present the potential of mathematical models in order to predict the availability of microelements (Fe, Zn, Mn) in acidic and alkaline soils of eastern Croatia. The fundamental database for availability prediction contains results of 22,616 soil samples from eastern Croatia representing an area of 88,714.46 ha of arable land. The mandatory results include soil pH, SOM, available P and K, hydrolytic acidity, and carbonate content. Additional data sets, including supplementary results of total (extracted by aqua regia, AR) and available (extracted by ethylenediaminetetraacetate, EDTA) micronutrient fraction, were used for modelling of micronutrient availability and for final model validation. The modelling micronutrient available fraction was created in 3 steps: (1) regression models of total (AR) and available (EDTA) micronutrients (Fe, Zn, Mn) concentration based on analytical results of soil pH, SOM, AR and EDTA micronutrients fractions; (2) prediction of the available micronutrients fraction (EDTA) based on the soil pH and SOM; (3) model validation using new data set with analytical results of soil pH, SOM, AR and EDTA. The model predicts that moderate micronutrients availability could be expected on 48.45 % (42,972.25 out of 88,714.46 ha) of arable land on average for Fe, Zn and Mn. A high availability could be on 29,32 % (25.982 ha) of arable land on average, but a very significant difference was found among Fe (47,37 %), Mn (39,01 %) and Zn (1,57 %) arable land with high availability. The most important prediction is the one that claims insufficient availability of micronutrient could be expected on 19,579.87 ha in average, what is 22.26 % of arable land. But low Fe availability was predicted on only 2.79 % (2,479,3 ha), significantly more land (22.60 %, 20,035.40 ha) with low Mn availability and the highest percentage (41,4 %) of soil with insufficient Zn availability (36,764.91 out of 88,714.46 ha). The validation shows the highest model accuracy for Zn and the lowest for Fe availability prediction

  • Phase transformations at heating of Sn–Ni–Zn powders obtained by cementation from solutions

    Materials Science. Non-Equilibrium Phase Transformations., Vol. 5 (2019), Issue 3, pg(s) 99-101

    The low-temperature method of Sn–Ni–Zn powders synthesis by cementation of tin and nickel with zinc powder from acidic solutions with the formation of “zinc core – porous nickel shell – external tin layer” structures has been proposed. The method provides metals ratio control in wide ranges (7–41 at. % of tin, 38–86 at. % of nickel and 7–24 at. % of zinc) by variation of the process duration. X-ray phase analysis data give evidence on the presence of β-Sn and Zn phases as well as NiZn3 and NiSn intermetallics in the powders obtained. Differential scanning calorimetry data show the availability of Sn–Zn eutectic with the melting point at 171.2 °C in the powders with high tin content (30–40 at. %). The formation of the ternary intermetallic τ1 phase (Ni3+xSn4Zn) has been established to occur as a result of the powders heating at 260 °C. The discovered low-temperature phase transformation in Sn–Ni–Zn system at 260 °C is of interest for electronic equipment assembly processes that include consecutive stages of soldering and resoldering.

  • MATERIALS

    ENVIRONMENTALLY FRIENDLY CONVERSION FILMS ON Zn AND TERNARY ZINC BASED ALLOYS – OBTAINING AND PROTECTIVE PROPERTIES

    Machines. Technologies. Materials., Vol. 10 (2016), Issue 9, pg(s) 44-47

    The objects of this study are galvanically deposited Zn and Zn-Ni-P coatings additionally treated (passivated) in environmentally friendly Cr(III)-based composition for obtaining of conversion films (CF). The aim of this treatment is to improve the corrosion-resistant properties of the coatings.

    The elemental composition and surface morphology of the newly obtained systems “galvanic coating/conversion film” are investigated with EDS and SEM analyses.

    Protective properties of the conversion films are defined with potentiodynamic polarization curves and polarization resistance measurements in a model medium containing chloride ions (5% NaCl) which leads to appearance of local corrosion.