Journal of Chemical Technology and Metallurgy

PYRIDAZINONE AS VERSATILE SCAFFOLD IN DRUG DISCOVERY: VIEW ON CURRENT DEVELOPMENT

2025-10-31T09:18:07+00:00

In modern medicinal chemistry, the pyridazinone core has emerged as a „versatile“ and privileged scaffold for the design of new therapeutic agents. Over the past decades, numerous pyridazinone derivatives have exhibited significant biological activities across diverse therapeutic areas including antiviral, antimicrobial, cardiovascular, anti-inflammatory, anticancer, and central nervous system disorders. This review discusses the structural diversity, structure-activity relationships (SAR), and pharmacological relevance of pyridazinone-based molecules. Furthermore, it highlights recent advances in hybrid drug design, where the pyridazinone moiety is combined with another pharmacophore to produce synergistic effect that enhance the biological activities of both components towards more than one target. Such hybridization strategy show the potential of pyridazinone scaffold as valuable templates for the development of multifunctional therapeutic agents.

MICROBIAL ELECTROLYSIS CELLS: ELECTROCATALYSTS AND CHARACTERIZATION METHODS - A REVIEW

2025-08-19T06:18:11+00:00

The growing global energy demand and depletion of fossil fuels require the development of sustainable alternatives. Hydrogen is widely recognized as a clean energy carrier due to its high energy density and environmentally benign combustion, producing only water. However, the high cost of hydrogen production remains a major barrier to its large-scale application, which stimulates research into novel production methods. One of the newest methods in this direction is biocatalyzed electrolysis, in which, along with hydrogen production, simultaneous purification of biodegradable waste products is carried out. Unlike traditional electrolyzers, the oxidation of the substrate is facilitated with the help of specific microorganisms capable of transferring extracellular electrons, generated by their catabolite processes to the anode of bioelectrochemical systems. One of the most important advantages of microbial electrolysis cell (MEC) is that they use substrates from renewable sources and are characterized by high efficiency. The reaction in which hydrogen is released at the cathode is inherent in several industrial electrolysis processes with aqueous electrolytes. The choice of cathode material has a strong influence on the rate of hydrogen release. A crucial factor for the practical implementation of MEC is to find effective cathode materials for operation at neutral pH, since electrogenic microorganisms are used.
This paper reviews the basic principles of microbial electrolysis cell, as well as various methods for physicochemical and electrochemical characterization of potential cathode materials for bioelectrochemical hydrogen production.

GELATINE - GLASS MICROBUBBLES HYDROCOLLOID AS POTENTIAL MEDICAL PHANTOM MATERIAL IN COMPUTED TOMOGRAPHY

2025-08-22T08:04:45+00:00

In the present study, gelatine - based hydrocolloids with glass microbubbles were designed and investigated as potential tissue mimicking materials for adipose and lung tissues in Computed tomography. Hydrocolloids contained 0.04 or 0.08 g mL^-1 gelatine and glass microbubbles in the range 0.04 - 0.28 g.mL^-1. Hounsfield units were derived for voltages in the range 70 - 120 kVp. All obtained values were negative with limits from about - 10 HU to about -445 HU. Mechanical performance was also investigated, giving comparatively high Young’s modulus up to about 1.2 MPa. Hounsfield units’ further decrease might be possible by 3D printing of the hydrocolloids, when printed with a speed from 60 to 90 mL h^-1, at a minimum temperature of 40 ^oC. Printability is limited up to 0.20 g mL^-1 glass
microbubbles concentration.

ASSESSMENT OF THE CHEMICAL COMPOSITION AND BIOLOGICAL ACTIVITY OF ESSENTIAL OIL FROM BULGARIAN YARROW (ACHILLEA MILLEFOLIUM L.)

2025-08-22T08:00:55+00:00

The present study aimed to investigate the chemical composition and biological activity of yarrow essential oil (Achillea millefolium) from Bulgaria. Gas chromatography-mass spectrometry (GC-MS) analysis, total reflection X-ray fluorescence (TXRF) technique, antioxidant activity (ABTS and DPPH methods), antimicrobial activity tests were used. Through an optimized procedure with Ga as an internal standard, thirteen elements - S, Cl, K, Ca, Cr, Mn, Fe, Ni, Cu, Zn, Se, and Br - were quantified. The highest concentrations were observed for S, Ca, and Fe (12.35 - 7.26 mg kg⁻¹), followed by Cl, K, Ni, Cu, and Zn (2.23 - 0.53 mg kg^-1). The dominant compounds identified by GC-MS analysis are monoterpene hydrocarbons, of which α-pinene (41.29 %) and β-pinene (27.15 %), limonene and p-cymene are predominant. The ABTS method a moderate degree radical neutralization with an IC₅₀ value of 9.15 ±
0.01 µg mL-1, while the DPPH method had a significantly lower IC₅₀ of 205.00 ± 0.03 µg mL-1, indicating selective antioxidant activity depending on the type of radicals. The maximum inhibition observed at 100 µg mL^-1 reached 95.13 % with the ABTS method and 29.82 % with the DPPH method. Bulgarian yarrow essential oil shows moderate activity against some Gram-negative bacteria, such as K. pneumoniae. and weak inhibitory activity against other pathogens, such as Staphylococcus aureus and Escherichia coli. It does not show activity against the molds Aspergillus niger and Aspergillus flavus.

ARGAN SHELL - DERIVED CARBON MATERIAL AS AN EFFICIENT SORBENT FOR TOXIC METAL REMOVAL FROM WATER SAMPLES

2025-09-16T07:12:22+00:00

Carbon - based materials derived from waste biomass have attracted attention in water treatment applications due to their porous structure, high surface area, and sustainability. In this study, an activated carbon produced from argan shell biomass, an abundant, low - cost byproduct of the Moroccan Argania spinosa tree, was evaluated for the removal of toxic heavy metals from wastewater. Batch adsorption experiments demonstrated that solution pH was an important parameter governing uptake performance. Near - neutral conditions enabled simultaneous and efficient removal of Pb (II), Zn (II), and Cu (II), achieving metal ions sorption of about 90 - 100 % within contact time of 40 min. Under strong acidic conditions (pH 1), metal uptake was inhibited due to surface protonation and competition
from excess H⁺ ions. At mildly alkaline conditions (pH 9), Pb (II) removal remained consistently high, whereas Zn (II) and Cu (II) removal decreased significantly. These findings identify pH 7.0 as the optimized operational parameter for effective and simultaneous removal of Pb (II), Zn (II), and Cu (II).

SYNTHESIS, HYDROLYTIC STABILITY AND ANTIVIRAL STUDIES OF SULFUR-BASED ANTI-INFLUENZA DRUGS

2025-10-21T08:17:14+00:00

Sulfur - containing building blocks represent highly favored scaffolds in various natural or synthetically obtained pharmacologically active molecules. Their diverse functionalities, including thioether, sulfonamide, sulfoxide, and others are often linked with the possibility to inhibit microbial growth and to regulate immune responses. Nowadays, approximately 25 % of all utilized small - molecule pharmaceuticals have been approved as organosulfur drugs or are clinical candidates. Herein, inspired by the medicinal power of such compounds, a series of potential sulfur based ligands against influenza A viruses was obtained by modification of amino group of anti - influenza drugs (rimantadine, amantadine and oseltamivir) and memantine. Furthermore, the structures of novel derivatives bearing
versatile sulfur - containing acyl moieties (cysteinyl-, thienyl-) were established by spectroscopic methods (¹H NMR, ¹³C NMR, (ATR)u_max, and HRMS). The newly synthesized amides were tested in vitro for antiviral activity against four influenza A viruses (A/Fort Monmouth/1/1947 (H1N1), A/Wuhan/359/1995 (H3N2), A/Jinnan/15/2009 (H1N1), and A/Aichi/2/68 (H3N2). Amongst the evaluated amides 1, 6, and 7 were the most active ones, inhibiting both the A/Fort Monmouth/1/1947 (H1N1) and A/Wuhan/359/1995 (H3N2) influenza virus strains, while amides 3 and 5 showed pronounced antiviral efficacy specifically against the A/Wuhan/359/1995 (H3N2) strain. Moreover, compounds 6 and 7 indicated remarkable inhibitory activity against the oseltamivir-resistant A/Jinnan/15/2009 strain.
Furthermore, the hydrolytic stability of desired amides was monitored in two model pH systems that mimic conditions in the stomach, and blood plasma, including pH 1.0, and 7.4, respectively.

INTEGRATED ALGORITHM FOR TOXICITY ASSESSMENT OF MINE TAILINGS AND SURROUNDING SOILS BASED ON CHEMICAL AND GERMINATION ASSAYS

2025-11-02T06:22:30+00:00

The evaluation of the environmental impact arising from mine tailing toxicity can be accomplished by chemical and biological assays. Several research groups and environmental agencies established working protocols for heavy metal determination and risk assessment. Nevertheless, there is no standardized methodology that integrates chemical and biological approaches for the toxicity assessment of soils and waters contaminated with heavy metals and metalloids. This study presents a comprehensive algorithm designed to assess the environmental toxicity of mine tailings and surrounding soils by applying a germination assay. Therefore, wheat germination bioassays and
evaluation of bioconcentration of As, Pb, Cu, Zn, Cd, Ag, Fe, Mn, Ni, and Cr in contaminated environmental samples
are carried out. The germination index showed results greater than 80 % classified as “excellent” in soil samples
P1 and P2, and less than 40 % in soil sample P3 due to high Pb toxicity. The capability of plant species to remediate
soils was evaluated by the Bioconcentration factor (BCF) and the Translocation factor (TF). The average results for
BCF, based on Pb, As, Zn, and Cu, were 0.25, and a low TF was obtained, with values ranging between 0.05 and 0.2.

OPTIMIZATION OF THE EXTRACTION CONDITIONS FOR THE Hg²⁺ - DITHIZONE COMPLEX IN CHLOROFORM AND ITS DETERMINATION BY UV-VIS SPECTROPHOTOMETRY

2025-10-30T09:37:19+00:00

This study aimed to optimize a UV - Vis spectrophotometric method for determining mercury based on its extraction with dithizone in chloroform. In the present work, the effects of pH, reagent concentration, stoichiometry of the complex were investigated. In addition, the sensitivity of the method was determined by calculating the molar absorbance, assessing the linearity and shaking time. Optimal conditions were established at pH ≈ 1.0 ± 0.1, using 4.00 mL of 5.00 mg L⁻¹ dithizone and 1.00 min shaking. Under these parameters, the method showed stable absorbance and reproducible results. The calibration was linear within 0.80 - 1.10 mg L⁻¹ Hg, and recovery tests yielded 71 - 74 % for spiked tap and deionized water samples. The optimized procedure provides reliable preliminary mercury determination and can be further adapted for complex matrices such as sediment, soil, or coal after microwave digestion.

CONTRIBUTION TO MINE TAILINGS TOXICITY ASSESSMENT

2025-10-10T11:14:05+00:00

Various chemical, biological, and biochemical assays are currently employed to evaluate the state of mine tailing dumps. However, some chemical approaches could overestimate the environmental footprint. This study presents an assessment of the current state of the inactive mine tailing dump area, employing a sequential chemical extraction procedure (SEP) to study heavy metal fractionation and contamination indices, thereby assessing the mobility and potential bioavailability. The studied samples contained elevated concentrations of As, Cu, Pb, and Zn, of which Pb was the most abundant element. The results showed that although high total heavy metal content in soil and mine tailing was observed, the mobility factors rarely exceeded 10 %. Moreover, the values of contamination factors, individual and global, were below 1 and 6, respectively. Thus, the mine tailings and surrounding soils could be classified as sources with low contamination potential. The applied approach could benefit the ongoing efforts toward the sustainable management and conservation of post-mining landscapes.

ANALYSIS OF THE DECAY OF THE 9B NUCLEUS IN THE DISSOCIATION OF THE 10C NUCLEUS

2025-08-19T06:16:40+00:00

The creation of beams of radioactive nuclei opens qualitatively new opportunities for studying their structural features and excited states. In the study of interactions at high energies, a significant role is played by the nuclear photo emulsion method, which is characterized by unique capabilities. Due to its extremely good spatial resolution (0.5 μm) compared to other methods and depending on the primary impulse, an angular accuracy of the tracks of relativistic fragments of about 10-3 radians can be obtained. This provides complete observation of all possible fragmentation decays of relativistic nuclei. In the current study, results are presented for the analysis of the decay of the unbound nucleus ⁹B in the dissociation of ¹⁰C nuclei. A comparative study is also performed between experimental data and Monte Carlo model calculations.

SOME PHYSICAL AND PHYSICOCHEMICAL PROPERTIES OF JELLY GELATINE DESSERTS PREPARED WITH WATER, ORANGE JUICE AND SUGAR

2025-10-02T15:10:31+00:00

The present study deals with investigations of some physical and physicochemical parameters of gelatine jelly desserts. Gels with different content of water or orange juice were prepared at varying gelatine and sugar content. Young‘s modulus, firmness, work of shear, pH, electric conductivity, index of refraction, and their dependences were evaluated and analysed with respect to the jelly content. The results show that the mechanical parameters have higher values for the orange juice-based hydrogels, which correlates to their lower pH and higher conductivity. The index of refraction corresponds to the physical density and it decreases linearly with the gelatine and sugar contents.

STUDY OF THE INFLUENCE OF THE PARTIAL REPLACING OF FELDSPARS WITH BIOGENIC HYDROXYAPATITE IN DENTAL TRANSPARENT GLAZE

2025-07-01T05:16:28+00:00

Four glass compositions for dental glaze on zirconium ceramics were melted at temperature at 1200 ^oC in corundum crucible with hold for 2 h at maximum temperature and rapidly cooled in water. The following raw materials for melting of the glasses were used: sodium feldspar, potassium feldspar, sodium nitrate, barium carbonate, lithium carbonate, boric acid and biogenic hydroxyapatite (BHA). The glass composition 1 does not contain hydroxyapatite. The other compositions (2, 3 and 4) contain 10, 20 and 30 wt. % BHA, respectively, which partially replaces sodium and potassium feldspars. The biogenic hydroxyapatite powder (BHA) was synthesized by us from Black Sea Rapana venosa shells and monocalcium phosphate monohydrate Ca(H₂PO₄ )₂.H₂O by solid-state synthesis at 1180 ^oC. With the present study by methods of XRD, FT-IR-ATR and Fluorescence analysis, we prove that 10 mass % BHA can participate in the composition of glass for dental glaze on zirconium ceramics in the place of feldspars, which would increase its bioactive properties and optical properties.

MULTIFERROICS – PREPARATION METHOD AND PHYSICAL PROPERTIES

2025-09-14T08:11:19+00:00

Polycrystalline Ba_0.5Sr_1.5MgNiFe₁₁Al₁O₂₂ powder materials were synthesized by modified citric acid - assisted sol - gel auto - combustion method. To enhance its crystallinity and phase purity, the material was sintered at 1190°C in air for five hours under ambient atmospheric conditions. The structural and magnetic properties of the prepared samples were evaluated by various techniques in view of understanding the correlations between their functional properties and crystal structure. Further, the magnetic measurement performed showed a decrease in the blocking temperature when the strength of the external magnetic field was increased. Such behavior indicates the presence of a spin - frozen or a spin - glass - like state, which we observed for the first time in this type of composite samples.

ALL-OPTICAL CHARACTERIZATION OF THE MAGNETIC PROPERTIES OF NANOCOMPOSITE BULK SAMPLE BASED ON FERRITES

2025-08-21T09:10:36+00:00

The magnetic properties of a nanocomposite bulk sample (Ba_0.5Sr_1.5NiMgFe₁₂O₂₂) were investigated in this paper from the perspective of its applications. All-optical magnetometry was used to characterize the sample. The electromagnetically induced absorption effect in a pump-probe configuration was exploited to produce magneto-optical resonances in a paraffin-coated rubidium vapor cell. The magnetic field created by the hard magnetic material was measured when the sample was positioned at different locations near the cell window. The results show that the optical system detected longitudinal and transverse magnetic fields caused by nanoparticles with randomized magnetic moments.

INVESTIGATION OF LASER PRODUCED NOBLE METAL-SEMICONDUCTOR NANOSTRUCTURES

2025-10-02T15:10:48+00:00

The ZnO/noble metal (both individually - Ag or Pd and in combination) nanocomposites are prepared by laser synthesis methods at atmospheric pressure in air. The formation of complex porous nanostructures is carried out by picosecond pulsed laser deposition at room temperature. The effect of post-deposition nanosecond laser annealing on the morphology and optical properties of the nanostructures is studied. The contribution of laser modifications to the change of a surface plasmon resonance (SPR) absorption band, and respectively, to the near-band-edge (NBE) and deep-level photoluminescence emission (DL), is investigated. The resonance absorption properties are obtained
for Ag/ZnO nanostructures before and after the laser annealing. While the SPR absorption band appears for mono- and bimetallic samples with palladium after the laser annealing. The plasmon resonance absorption contributes to the enhancement of photoluminescence band-edge UV emission of all samples and suppression of the strong Vis DL emission of monometallic noble metal/ZnO nanocomposites after the annealing. The low level of the DLE emission is observed before the annealing of the bimetallic sample Ag-Pd/ZnO, with annealing slightly affecting it. This sample demonstrates significantly smaller nanoparticles (NPs), as well as a narrower size distribution in comparison to monometallic noble metal/ZnO nanocomposites.

RESOURCE-SAVING APPROACH TO THE TECHNOLOGY OF LASER SURFACE ALLOYING OF METAL WORKPIECES AND ITS THERMODYNAMIC SUBSTANTIATION: A CASE STUDY OF ALLOYING WITH CHROMIUM

2025-06-01T01:08:21+00:00

This article is devoted to the investigation of the prospects for resource-saving development of laser surface alloying technology for machine-building blanks by replacing the expensive pure metal powders used for this purpose with their simple oxides, while ensuring complete slag-free reduction of the latter using a strongly and rapidly oxidizing gas such as methane. To justify the effectiveness of the proposed approach, a specific case study was conducted involving the laser surface alloying of AISI 1045 structural steel with chromium recovered from its trivalent oxide Cr₂O₃ of chemical purity. To this aim, a complete thermodynamic analysis of the interaction of Cr₂O₃ - CH₄ components was performed in the temperature range of 400 - 2500 K, which is relevant for laser surface doping, with consideration of the decomposition of part of the methane that was directly exposed to the focused laser beam. It has been established that the chromium reduction process proceeds in two stages: solid phase (1150 - 1350 K) and liquid phase (1550 - 2000 K). In the first case, the process proceeds with the formation of chromium carbides Cr₃C₂ and Cr₇C₃, and in the second case, with the decomposition of the latter into elemental (condensed) chromium and free (amorphous) carbon, which contributes to the further complete carbothermal reduction of the residual locations of the initial oxide layer. It is recommended that the second stage of recovery be carried out under dynamic vacuum conditions, ensuring the removal of CO and H₂ reaction gases. The generalization and implementation of the proposed technological solution can lead to significant savings in expensive alloying element powders, as well as reduce their irretrievable losses in the form of burn-off and blow-off caused by laser evaporation. It is noted that the proposed resource-saving approach to surface laser alloying technology may serve as a significant driver for further progress in this important scientific and technical field.

CRYSTALLOGRAPHIC AND ELECTRICAL PARAMETERS OF TiO2 THIN FILMS DEPOSITED ON Al SUBSTRATES

2025-08-26T06:41:28+00:00

In this study, titanium oxide thin films were synthesized on Al substrates by the direct current reactive magnetron sputtering technique. During the experiments, a pure Ti interlayer on aluminum substrates was deposited. Part of the formed samples were heated to a temperature of 180°C for 120 min. The TiO₂ thin films were deposited on heated and unheated Al substrates with Ti interlayer. Important crystallographic parameters of samples, like phase composition, formation of preferred crystallographic orientation, and lattice parameters were studied using X-ray diffraction analysis. Other surface characteristics, such as surface roughness, and distribution of the measured heights were determined using Atomic Force Microscopy. Electrical impedance spectroscopy was used to determine the electrical
characteristics of specimens. The results obtained for the electrical properties of the modified surfaces were discussed in relation to the investigated structure of the samples. The results showed that the applied preliminary heating of the deposited Ti interlayer on the Al substrate significantly influenced the electrical impedance of the Ti/TiO₂ coating.

HOT CORROSION MECHANISM OF NiCr - 40 % Cr3C2 HIGH-VELOCITY OXY-FUEL THERMAL SPRAY COATINGS ON STAINLESS STEEL 304

2025-01-28T04:56:32+00:00

The hot corrosion characterization of High-Velocity Oxy-Fuel (HVOF) thermally sprayed coatings of 60 %
NiCr_{[37 μm]} - 40 % Cr₃C₂ on stainless steel 304 substrate was analysed by exposure to molten salts Na₂SO₄ and NaCl of various mole percentages at a temperature of 750^oC. The application of finer NiCr feedstock 37 μm has been effective to improve the quality of thermal spray coatings both in physical and mechanical properties. In this study, the NiCr based coatings is evaluated in the hot corrosion test to verify its reliability. XRD and SEM characterizations were applied to analyse compounds resulting from the hot corrosion process, the depth of pitting, oxide thickness, spalling, and decarburization. Results showed that the higher the mole percentage of salt NaCl, the thicker the oxide and the deeper the pitting formed on the coating surface, and that the oxide formed was Cr₂O₃ and NiO. Furthermore,
decarburization of Cr₃C₂ was severe and formed due to hot corrosion on the specimens were classified as type II, in the other hand the decarburization was not detected on the surface of the specimen after the hot corrosion test. However, spalling was evident on every specimen.

INTERCRITERIA AND REGRESSION ANALYSES TO DECIPHER THE MEANING OF CHARACTERISTICS OF FEEDS CONTAINING RESIDUES FOR THE PREDICTION OF CATALYTIC CRACKING PERFORMANCE

2025-07-08T12:28:37+00:00

Data for catalytic cracking of ten feeds, which contain residues were evaluated by using intercriteria and
regression analyses with the aim to verify the established in a previous study relations, based on catalytic cracking of nine vacuum gas oils, and to develop new correlations to predict product selectivity. The previously developed correlation that calculates vacuum gas oil conversion from aromatic carbon and hydrogen contents was found to be the best for prediction of conversion of the feeds containing residues too. It was found that the selectivity towards production of dry gas, coke, and gasoline of both VGOs and residue containing feeds can be predicted from the same feed characteristics: aromatic carbon, hydrogen, sulphur, and polars contents, and molecular weight. However, the bottoms cracking of the VGOs needs to be modelled separately from that of the residue containing feeds.

THE ISSUE OF METAL EXTRACTION DURING OZONATION PURIFICATION OF COPPER PRODUCTION PROCESS SOLUTIONS

2025-05-21T01:35:08+00:00

Over ten billion tons of minerals are mined worldwide each year, generating vast volumes of acidic process solutions rich in copper, zinc, iron, molybdenum and other metals. Effective treatment and resource recovery from these liquid wastes is essential both for environmental protection and for conserving strategic reserves. In this study, we investigate ozone-air bubbling as a single-stage purification and metal-extraction method for real copper-production effluents from JSC Almalyk MMC. Ozone consumption and metal liberation kinetics were quantified as functions of metal ion concentration, ozone dosage, and contact time. Under optimized conditions, more than 99 % of Cu, Zn,
Fe and Mo was precipitated within one hour, driving residual concentrations below 0.01 mg L-1 and yielding a clear, reusable effluent. Based on these results, we propose a conceptual flow scheme that integrates ozone-induced oxidation of metal-ligand complexes with downstream hydroxide precipitation and filtration. This ozone-based process offers a scalable, chemical-free route to both recover valuable metals and produce high-quality process water, supporting closed-loop operation in copper refining and potentially other metallurgical industries.

FEASIBILITY STUDY INTO THE POSSIBILITY OF MANGANESE ORE ENRICHMENT WASTE USE FOR SORBENT MATERIAL DEVELOPMENT

2025-05-15T01:20:28+00:00

This study explores the synthesis of sorption-active phosphate materials from manganese ore enrichment tailings of the Zhairem deposit. The initial tailings, predominantly composed of calcite (76.4 %), quartz (16.4 %), and braunite, were characterized by XRD and EPMA. Acid-thermal treatment with phosphoric acid followed by calcination at 200-800°C yielded calcium - manganese phosphate materials. Phase transformations were monitored via XRD, showing formation of crystalline phosphates at 200 - 600°C and a glassy phase at 800°C. The product synthesized at 600°C demonstrated the lowest water solubility (9.91 %), highest pore volume (0.175 cm³ g-1), and optimal sorption capacity for Ni2+ (0.2934 mg-eq g-1), which increased to 0.4697 mg-eq g^-1 after 0.4 wt. % of HCl activation. The enhanced performance is attributed to the formation of low-solubility polyphosphates and well-developed porous structures. SEM confirmed porous morphology at 600°C and denser, glassy structure at 800°C. The synthesized material showed no toxic elements such as Pb, Cd, or As, making it suitable for environmental applications. The findings indicate that Zhairem tailings are a promising raw material for producing effective sorbents for heavy metal removal, especially after acid activation. The optimal product is the calcium-manganese phosphate synthesized at 600°C.

INFLUENCE OF DIAMOND BURNISHING PROCESS PARAMETERS ON STRAIN-INDUCED α’-MARTENSITE IN 304 CHROMIUM-NICKEL AUSTENITIC STAINLESS STEEL

2025-06-05T03:06:58+00:00

When chromium-nickel austenitic stainless steels must satisfy a requirement for a high degree of strain-hardening, the nickel content is limited to 8 - 9 wt. %. The surface cold working of these steels causes the martensitic transformation γ → α′. Thus, the surface microhardness and residual compressive stresses increase due to the presence of the harder strain-induced a’-martensite phase. This article investigates the influence of the governing factors of diamond burnishing (DB) on the percentage content of the a’-martensite in the surface layer of AISI 304 steel using planned experiment, analysis of variance and regression analysis. A mathematical model of the percentage content of a’- martensite depending on the burnishing force, feed rate and burnishing velocity was created. Of the three governing factors, the most significant is feed rate, and the least important is burnishing force. Thermal effects have a greater impact on martensitic transformation γ → α′ compared to the mechanical effect. The percentage of martensite in the surface and subsurface layers is necessary information for determining the residual stresses by the X-ray method when studying the effect of DB on the surface integrity of austenitic stainless steels.