Effect of electrolysis parameters on corrosion resistance of extra-low carbon high silicon iron-based alloy

Purpose High silicon iron-based alloys possess excellent corrosion resistance in certain specific media, but the effects of electrolysis parameters on corrosion resistance remain unknown. This study aims to guide the development and application of an extra-low carbon high silicon iron-based alloy (ECHSIA) in electrode plates. Design/methodology/approach The corrosion resistance of ECHSIA and a conventional high-silicon cast iron (CHSCI) was analyzed through experimental characterizations. The morphology was observed by scanning electron microscopy. The influence of electrolysis parameters on the corrosion resistance of ECHSIA was investigated through corrosion experiments. The relationship between the electrolysis parameters and the corrosion resistance of ECHSIA was statistically investigated using the grey correlation analysis method. Findings The corrosion resistance of the ECHSIA is better than that of the CHSCI. The corrosion rate showed an increasing tendency with the increase in the nitric acid concentration (CHNO3), electrolyte temperature and current density. The grey correlation analysis results showed that the CHNO3 was the main factor affecting the corrosion rate of the ECHSIA. Originality/value An ECHSIA with a single ferrite microstructure was prepared. This study provides a guideline for the future development and application of ECHSIAs as electrode plates.

Processing of waste slag of non-ferrous metallurgy for the purpose of its complex utilization as a secondary mineral raw material

This article provides an overview of the methods of processing slag from welting is given, different approaches and attempts of scientists from a number of countries aimed at processing such slags are considered. In the course of the review it was found that a huge number of the following methods and methods of processing from waelz slag, there is not a single option that has sufficient complexity of processing, and that at the moment are in the dumps toxins from waelz never found its use as a secondary raw material. The elemental chemical composition of the slag from welting, which is represented by compounds of calcium, silicon, iron, aluminum, carbon and heavy nonferrous metals in the form of zinc and lead, is determined. Thus, it is established that for many years, the slags from waelz that have not found their application and are in the dump at the moment continue to have a polluting effect on the environment. Ill. 1. Ref. 63.

Proton magnetization relaxation in aqueous suspensions of composite silicon-iron nanoparticles for biomedical applications

Silicon-iron composite nanoparticles produced by arc-discharge plasma ablation method were characterized by scanning electron microscopy, dynamic light scattering, X-ray fluorescence diffractometry, and the effect of iron content and size of the nanoparticles on hydrogen nuclei magnetization relaxation were investigated by nuclear magnetic resonance relaxometry. It was shown that increasing in iron content during the synthesis leads to distortion of the spherical shape of the nanoparticles and increasing of their mean sizes from 140 nm to 350 nm. Nonlinear dependence of the longitudinal and transverse relaxivities from iron content was demonstrated. Increase in the iron concentration above 2.5 at. % leads to reduction of the both relaxivities, which can be explained by nonuniform distribution of iron and formation of iron containing agglomerates. It was shown that transverse and longitudinal relaxivities of the nanoparticles in their aqueous solutions inversely proportional from their hydrodynamic diameters in the range of 100 – 300 nm. The possibilities of using composite silicon-iron nanoparticles for biomedical applications are discussed.

TO THE QUESTION OF INDUSTRIAL AEROSOL CONTROL IN THE PROCESSING OF BLISTER COPPER

Due to the predominance of PM1 particles in the air samples, the following metals were found in the aerosol: copper, zinc, silicon, iron, lead, sulfur, arsenic, aluminum, antimony, tin, magnesium, cadmium and several other metals. The content of sulfates was significantly noted. These physical and chemical properties show a considerable toxic potential of industrial aerosol. The MPC of lead, sulfur and silicon dioxides, as well as nitrogen oxides and formaldehyde were detected in the working air. Meanwhile, copper, zinc, and iron did not exceed their MPC. Moreover, an underestimation of the aerosol was observed within the framework of industrial control. It has been found that the aerosol components may have an irritating, reprotoxic, allergenic, and carcinogenic effect on the body. Further consideration of the dispersed and chemical composition of the aerosol is required to determine the concentration of identified substances in the working air and the limiting components determining its biological effect.

Ash content in fruit samples of the Actinidia kolomikta genetic collection

Among the representatives of the Actinidia Lindl. genus, Actinidia kolomikta (Siebold et Zucc.) Planch. is valued as the most winter-hardy variety with high taste and dietary properties. The Federal Horticultural Research Centre for Breeding, Agrotechnology and Nursery has a live collection of Actinidia, which includes more than a hundred cultivated forms and varieties. In this study, ash content in Actinidia kolomikta fruits of 10 varieties and collection samples was studied by energy-dispersive X-ray spectroscopy using an analytical scanning electron microscope JEOL JSM6090 LA. A decreasing series was established for the accumulation of ash elements in the fruits of the studied samples: Ca> K> P> Mg> Mo> S> Se> Zn> Fe> Co> Si> Na. In terms of accumulation of useful macro- and micronutrients, the most valuable varieties were identified. The total accumulation of macronutrients in the fruit ash ranged from 28.6 to 45.3 wt%. This indicator was the highest in the fruits of Dolgovechnaya, Uslada and Vinogradnaya (42.068–45.638 wt%). The fruits of the Uslada variety were distinguished by a high content of phosphorus (5.89), silicon (0.504), sulfur (1.34) and potassium (23.596 wt%). In terms of micronutrient accumulation, the Pamyati Kolbasinoj variety (4.904 wt%) showed the highest levels of molybdenum (3.804) and selenium (0.801 wt%). Iron accumulated more readily in the fruits of the Uslada variety (0.161), cobalt — in Nadezhda (0.157), zinc — in Vinogradnaya (0.247) and Chempion (0.195). A statistically significant positive correlation (r > 0.7) was revealed in the accumulation of the following pairs of ash elements: sodium — sulfur (r = 0.70), phosphorus — potassium (r = 0.75), silicon — iron (r = 0.76), as well as molybdenum with phosphorus (r = 0.84), sulfur (r = 0.83) and potassium (r = 0.71). A statistically significant negative correlation was observed only for the accumulation of phosphorus and calcium (r = -0.71). According to the results, the fruits of the Actinidia kolomikta varieties under study can be an additional or alternative source of dietary minerals in functional food products.

RHEINFELDEN CASTASIL-21

Rheinfelden Castasil-21 (Ci-21, AlSi9Sr) is an aluminum-silicon-iron-strontium high pressure die casting (HPDC) alloy. It was developed by Rheinfelden Alloys GmbH and Co. KG for castings that require an outstanding combination of electrical and/or thermal conductivity. This datasheet provides information on composition, physical properties, hardness, elasticity, and tensile properties. It also includes information on corrosion resistance as well as casting, heat treating, machining, and joining. Filing Code: Al-476. Producer or source: Rheinfelden Alloys GmbH.

Study of the composition and properties of the copper ore processing tailings of PJSC Gaysky Mining and Processing Plant

The article provides the results of studies to establish the environmental impact of the copper ore processing tailings storage facilities of PJSC Gaysky Mining and Processing Plant on the natural waters, as well as to estimate the value of the tailings if used as a technogenic raw material. The work was carried out using the results of the grainsize analysis and qualitative and quantitative assays of the copper ore processing tailings from the TSF of the concentrator, as well as the results of surface and ground water sampling in the area of the TSF. The grain-size analysis was carried out by the sieve method and used to classify the processing tailings into four size classes. The X-ray fluorescence analysis method was used to establish the composition of the tailings; the predominance of oxides of silicon, iron, sulfur, and aluminum was observed. Using an inductively coupled plasma emission spectrometer and an atomic absorption spectrometer, the total contents of heavy metals and toxic elements were measured, as well as the gold and silver grades. The results obtained indicate that operation of the copper ore processing tailings storage facilities is associated with the washout of both valuable and hazardous chemical components with the infiltration waters into the groundwater. All chemical studies and assays were carried out at the Scientific and Educational Center for Shared Use of the St. Petersburg Mining University and the laboratory of the Process Research Department of JSC Mekhanobr Engineering.

Copper Slag of Pyroxene Composition as a Partial Replacement of Natural Aggregate for Concrete Production

Copper slag, a by-product of the pyrometallurgical process used for obtaining copper from copper ore in Bor, Serbia, contains mainly silicon, iron, calcium, and aluminium oxides. Due to such properties, it is disposed of in landfills. Despite the favourable technical properties copper slag aggregates possess, such as low-water absorption (WA24 0.6%), low resistance to fragmentation (LA 10%), and low resistance to wear (MDE 4%), its use in the construction industry is still limited. The results of testing the technical properties of copper slag aggregates (CSAs) as a potential replacement for natural river aggregate (RA) are presented in this paper. The experiments included tests on three concrete mixtures with partial replacement of coarse natural aggregate with copper slag. The replacement of RA particle sizes of 8/16 mm and 16/31.5 mm with CSA in the amount of 20% + 50% and 50% + 50% resulted in an increase in the compressive strength of 12.4% and 10.5%, respectively. The increase of CSA content led to a decrease in water penetration resistance and salt-frost resistance of concrete, whereas the resistance to chloride ion penetration did not change significantly.

Influence of Strain Rate, Temperature and Chemical Composition on High Silicon Ductile Iron

Today, the use of solution hardened ductile iron is limited by brittleness under certain conditions. If chassis components are subjected to loads having high strain rates exceeding those imposed during tensile testing at sub-zero temperatures, unexpected failure can occur. Therefore, it is the purpose of this review to discuss three main mechanisms, which have been related to brittle failure in high silicon irons: intercritical embrittlement, the integrity of the ferritic matrix and deformation mechanisms in the graphite. Intercritical embrittlement is mainly attributed to the formation of Mg- and S-rich grain boundary films. The formation of these films is suppressed if the amount of free Mg- and MgS-rich inclusions is limited by avoiding excess Mg and/or by the passivation of free Mg with P. If the grain boundary film is not suppressed, the high silicon iron has very low elongations in the shakeout temperature regime: 300 to 500 °C. The integrity and strength of the ferrite are limited by the reduced ordering of the silicumferrite with increasing silicon content, once the “ordinary” ferrite is saturated at 3% silicon, depending on the cooling conditions. Finally, the graphite damaging mechanisms are what dictate the properties most at low temperatures (sub −20 °C).