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1

Insight into the corrosion in non-ferrous alloy heat exchangers

Lachowicz Marzena M., Lachowicz Maciej B.

Ochrona przed Korozją

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2025

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nr 1

2--11

EN

Selected issues relating to the corrosion of non-ferrous heat exchanger components in their operating environment have been presented. With the increasing demand for such equipment, the number of reported corrosion-related failures is steadily increasing, resulting in rising operating costs. This paper introduces the different types of corrosion and defines selected corrosion problems affecting aluminium heat exchanger components. Macroscopic images are shown and the mechanism of corrosion caused by the presence of organic decomposition products on the surface of copper elements is discussed. In relation to copper, an example of corrosion caused by sulphate ions is also presented. The study also includes an example related to the hydrogenation of a titanium heat exchanger plate. The analyses presented in this paper are related to engineering practice and are relevant to the design of thermal energy exchange devices. The possibility of early detection of existing corrosion hazards will also help to prevent potential mechanical failures in heat exchangers.

PL

W pracy przedstawiono wybrane zagadnienia związane z korozją nieżelaznych elementów wymienników ciepła w ich środowisku eksploatacyjnym. Rosnący popyt na te urządzenia powoduje, że ilość odnotowanych awarii wywołanych korozją stale wzrasta, co wiąże się z rosnącymi kosztami ich eksploatacji. W pracy przedstawiono różne typy korozji, a także zdefiniowano wybrane problemy korozyjne dotyczące aluminiowych elementów wymienników ciepła. Pokazano obrazy makroskopowe oraz omówiono mechanizm korozji spowodowanej obecnością produktów rozkładu substancji organicznych na powierzchni elementów miedzianych. W odniesieniu do miedzi przedstawiono również przykład korozji wywołanej jonami siarczanowymi. W ramach badań przedstawiono także przykład związany z nawodorowaniem tytanowej płyty wymiennika ciepła. Przedstawione w pracy analizy związane są z praktyką inżynierską i stanowią istotne znaczenie dla projektowania urządzeń służących do wymiany energii cieplnej. Możliwość wczesnej detekcji istniejących zagrożeń korozyjnych pozwoli również zapobiegać potencjalnym awariom mechanicznym w wymiennikach ciepła.

2

Improvement of the corrosion behaviour of mild steel by deposition of Zn–Ni–Cu–Fe–Cd from an acetate sulphate bath

Evecen Meryem, Alfalah Mothana Ghazi, Saracoglu Murat, Kandemirli Fatma

Ochrona przed Korozją

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2025

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nr 2

41--47

PL

Pięcioskładnikowy stop Zn–Ni–Cu–Fe–Cd został osadzony elektrolitycznie na stali miękkiej w kąpieli octanowo-siarczanowej z zastosowaniem tylko potencjału katodowego w woltamperometrii liniowej. Zbadano wpływ szybkości skanowania (1 mV/s, 5 mV/s, 10 mV/s), a także wpływ dodatków organicznych: 4-(4-nitrofenylo)-3-tiosemikarbazyd lub 4-(3-metoksyfenylo)-3-tiosemikarbazyd, na wygląd powierzchni i skład osadzanej powłoki. Do zbadania zachowania korozyjnego stopu po zanurzeniu w roztworze zawierającym 1 M HCl wykorzystano trzy techniki elektrochemiczne: polaryzację potencjodynamiczną (PDP), polaryzację liniową (LPR) i elektrochemiczną spektroskopię impedancyjną (EIS). Po osadzeniu przeprowadzono analizę za pomocą spektroskopii rentgenowskiej z dyspersją energii (EDX) i skaningowej mikroskopii elektronowej (SEM), aby wizualnie ocenić powłoki. Najniższą gęstość prądu korozyjnego, najwyższą odporność na korozję i najwyższą impedancję zaobserwowano w każdym układzie stopowym przy szybkości skanowania wynoszącej 1 mV/s. Wartości te wynosiły odpowiednio: 67 μA/cm−2, 51 μA/cm−2 i 7,6 μA/cm−2 dla PDP, 965 Ω · cm2, 1117 Ω · cm2 i 2853 Ω · cm2 dla LPR oraz 1602 Ω · cm2, 12 938 Ω · cm2 i 1595 Ω · cm2 dla EIS, co odpowiadało kolejno: powłokom bez dodatków, powłokom z dodatkiem 4-(4-nitrofenylo)-3-tiosemikarbazydu i powłokom z dodatkiem 4-(3-metoksyfenylo)-3-tiosemikarbazydu. Na podstawie wyników badań SEM i EDX stwierdzono, że 4-(3-metoksyfenylo)-3-tiosemikarbazyd ma większy wpływ na powłokę niż 4-(4-nitrofenylo)-3-tiosemikarbazyd, prawdopodobnie ze względu na jego lepszą adsorpcję na powierzchni miękkiej stali.

EN

Zn–Ni–Cu–Fe–Cd quinary alloy was successfully electrodeposited on mild steel from acetate-sulphate baths with only cathodic potential applied during linear sweep voltammetry. The influence of scan rate (1 mV/s, 5 mV/s and 10 mV/s) as well as the effect of organic additives: 4-(4-nitrophenyl)-3-thiosemicarbazide or 4-(3-methoxyphenyl)-3-thiosemicarbazide, on the surface appearance and deposit composition were investigated. Three electrochemical techniques, potentiodynamic polarisation (PDP), linear polarisation resistance (LPR) and electrochemical impedance spectroscopy (EIS) were used to investigate the corrosion behaviour of the alloy composition after immersion in a solution containing 1 M HCl. Energy dispersive X-ray (EDX) and scanning electron microscopy (SEM) were carried out after deposition to provide a visual aspect of the coating. The lowest corrosion current density, the highest corrosion resistance, and the highest impedance were observed in each alloy system at a scan rate of 1 mV/s. These values were: 67 μA/cm−2, 51 μA/cm−2, and 7.6 μA/cm−2 for PDP, 965 Ω · cm², 1117 Ω · cm², and 2853 Ω · cm² for LPR, and 1602 Ω · cm², 12938 Ω · cm², and 1595 Ω · cm² for EIS, corresponding to coatings without additives, coatings with the additive 4-(4-nitrophenyl)-3-thiosemicarbazide, and coatings with the additive 4-(3-methoxyphenyl)-3-thiosemicarbazide, respectively. From the SEM and EDX results it was concluded that 4-(3-methoxyphenyl)-3-thiosemicarbazide has a more pronounced effect on the coating than 4-(4-nitrophenyl)-3-thiosemicarbazide, probably due to its better adsorption on the surface of soft steel.

3

Assessing the loading capacity of walnut peels as a nanobiomass for the biosorption of certain heavy metals from wastewater

Khalaf Sarah Adnan, Shartooh Sufyan Mohammed, Abdullah Shihan Mayada

Journal of Ecological Engineering

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2025

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Vol. 26, nr 2

169--182

EN

Bio-removal of heavy metal pollution remains a major challenge in environmental biotechnology. This paper focuses on the potential of carbon nanoparticles for biosorption of zinc, copper, and cadmium ions from aqueous solutions, employing economical and environmentally sound plant wastes. Walnut peels were washed by distilled water, mixed with KOH, burned at 650 °C, and treated ultrasonically to obtain carbon nanoparticles. Standard solutions of the heavy metals under study were prepared based on calculations of the molecular weights of the relevant metal salts Zn, Cu, and Cd, the metal ions were estimated in both treated and wastewater sample. The experiment included evaluating the effect of some environmental factors on the process of biosorption of heavy metals from wastewater to choose the optimal conditions for the adsorption process. These environmental factors included the initial metal concentration, pH, temperature, retention time, and biomass. The optimum conditions of initial metal concentration, pH, temperature, retention time, and biomass were recorded as 100 mg/l, pH of 7, 45 °C., 60 min., 0.2 g respectively. These results were supported by XRD examination, which indicated the presence of two Bragg diffraction peaks in the carbon nanoparticles, and TEM results also indicated the presence of inhomogeneous particles, as well as the irregular shape of the surface of the carbon nanoparticles with a large surface area, according to SEM examination. However, the optimal adsorption conditions were applied in a laboratory treatment unit, which showed its efficiency in removing heavy metal ions from wastewater. Carbon nanoparticles derived from walnut shells can be employed as excellent adsorbents for removing heavy metal ions from aqueous solutions.

4

Experimental study of aluminum-polytetraflouroethylene functionally graded materials tribological properties

Omran Ghufran Hamza, Abass Basim Ajeel, Radhi Nabaa Sattar

Diagnostyka

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2025

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Vol. 26, No. 2

art. no. 202510

EN

The current work aims to experimentally investigate the sliding wear characteristics of three, four, and fivelayer PTFE-Al functionally graded materials (FGMs). FGMs with different layers of (75-25, 50-50, 25-75, and 0-100) wt.% Aluminium and PTFE have been synthesized using the powder compaction technique. The tribological properties of such materials are investigated using a Pin-on-disc wear test machine with three process parameters: applied loads (1, 3, and 5) N, rotational speeds (100, 250, and 450) rpm, and sliding times (5, 10, and 15) minutes. The obtained results show that the wear rate of the PTFE can be mitigated with the existence of the Al. However, it increases with the applied load, sliding distance, and rubbing velocities. It was also noted that the wear rate of the different layers decreases as the weight fraction of Aluminium increases due to the increase of the material hardness. Scanning electron microscope (SEM) with Energy Dispersive X-ray spectrometry (EDS) is used to analyse the worn surfaces. The SEM with EDS analysis showed that the predominant wear of the different functionally graded materials and their layers is an abrasive as a result of the wear debris and score formation.

5

New technique for sharpening ultra-thin wires for the drawing process: incremental furnace stretching

Kustra Piotr, Milenin Andrij

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2025

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Vol. 73, nr 2

art. no. e153425

EN

In the wire drawing process, the wire is subjected to sharpening before each drawing. Traditional methods for sharpening wires involve one of the following techniques: crimping, grinding, rolling, chemical etching, or stretching within a furnace. Wire sharpening becomes especially difficult in the manufacture of ultra-thin wire. This study proposes and examines a novel technique for sharpening thin and ultra-thin wires through specialized stretching in a furnace. This study proposes and investigates a new technique for sharpening thin and ultra-thin wires based on stretching them in the furnace. Using a rheology-based concept of wire deformation during stretching, this study offers a substantial enhancement in the maximum attainable thinning of the wire during sharpening. Technically, this advancement is achieved by transitioning from a single-stage stretching process to an incremental one, characterized by small increments of deformation at each stage. In addition to incremental stretching, the proposed method includes simultaneous movement of the wire through a continuous micro furnace, repeated at each stage of elongation, which achieves thinning of the wire end of a given length. This study theoretically and experimentally explores further potentialities of this approach concerning the fabrication of ultra-thin wire. The findings show that the effectiveness of the proposed method strongly depends on the shape of the stress-strain curve of the wire material. For example, the conducted research demonstrated that this method is more effective for brass than for copper wire.

6

The design and optimization of the mixing process for Udimet 720LI nickel alloy manufacturing from elemental powders

Skonieczna Wiktoria, Wojtaszek Marek, Lypchanskyi Oleksandr, Cichocki Kamil, Goły Marcin, Kopyściański Mateusz, Zientara Dariusz, Stanik Rafał, Gude Maik, Prahl Urlich

Advances in Science and Technology. Research Journal

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2025

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Vol. 19, no. 3

1--11

EN

The objective of the study was to design an efficient production route for the U720LI nickel alloy using elemental powders as initial materials. The powder mixing process was carried out using a double-cone mixer and an Attritor mill, respectively. A device proper for effective mixing and mechanical alloying of powder particles was selected, and the most favorable parameters for the powder mixing process necessary for the production of the alloy were developed. The analysis of the results showed that significantly higher efficiency in mixing the powders necessary for producing the U720LI alloy was achieved using the Attritor mill. In further tests, the most favorable operating parameters of this device were determined by mixing materials at different rotational speeds. The results demonstrated that the most effective method of powder bonding among the tested variants was mixing in the Attritor mill at the identified high rotational speeds. A highly densified product with a homogeneous microstructure and free of external and internal defects was obtained, suitable for use both as a finished product and as high-quality feedstock for hot metal forming processing.

7

Investigation of the effect of grain size on longitudinal critically refracted ultrasonic wave time-of-flight and speed of penetration in material

Dive Vikas Pralhad, Solepatil Sandesh, Mali Amol, Dambhare Sunil, Kolekar Aniket

Advances in Science and Technology. Research Journal

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2025

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Vol. 19, no. 6

391--402

EN

This examination investigates the governance of grain size on the Time-of-Flight (TOF) and speed of longitudinal critically refracted (LCR) waves in metallic materials. LCR waves are pivotal in non-destructive assessment and material characterization due to their sensitivity to microstructural variations. We conducted experiments on typical varying grain sizes and analyzed the propagation of LCR waves. The grain size of material changes when subjected to mechanical and thermal operations. In the present study the specimens of as received material cut to 100 X 50 X 8 mm dimensions. The prepared specimens first stress relieved and then subjected to the heat treatments at a temperature 440 0C, 480 0C, 500 0C, 540 0C, and 560 0C for 30 minute in vacuum furnace respectively. The TOF and speed of LCR wave measured with ultrasonic instrument and 5 MHz frequency transducers. The grain dimensions and the grain structure changes with the heat treatments. At 560 0C temperature the grains became courser and the size of the grains increased to 150µm. The grains get elongated at 500 0C and 540 0C temperature with equiaxed grains structure. The grain size of the specimens heated at 500 0C and 540 0C temperature measured as 84µm and 100µm respectively. The LCR wave speed and TOF established a linear relation with grain size effect. The LCR wave TOF and grain dimensions established negative relation, The LCR TOF smaller at higher grain size and higher at lower grain size. The LCR wave speed and grain dimensions established positive relation, with rise in grain size LCR wave speed increases and at lower grain size the LCR wave speed observed smaller. The change in ±10µm grain size changes the TOF and speed wave by ∓ 0.0005µsec and ±0.2411m/s respectively. The measurements of TOF and speed of LCR wave performed with uncertainty ± 0.000029 and ± 0.010 respectively. Our results indicate a significant correlation between grain size and both TOF and wave speed, highlighting the importance of considering grain size in ultrasonic testing and material evaluation.

8

Influence of applied coating time on nano hydroxyapatite/ chitosan coating on 316L stainless steel alloy using electrophoretic deposition for biomedical application

Hazber Aya Muhsun, Jassim Ayad Naseef, Gattmah Jabbar Qassim, Kutm Jaber Kasem, Poorsalehi Fatemeh

Advances in Science and Technology. Research Journal

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2025

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Vol. 19, no. 5

1--13

EN

In this work, an electrophoretic deposition (EPD) method was utilized to cover a biocompatible stainless steel medical grid type 316L with nanoparticles of hydroxyapatite (HA). ln conjunction with the biopolymer chitosan (CHT), as a binder, it enhances the adhesive capabilities of a substrate. The chosen bio-coating method is the EPD process of 316L Stainless Steel alloy due to its ease of use, low cost, and capacity to coat intricate items. Consequently, this research studied different concentrations of the materials utilized, the most significant variables, and their effects in order to acquire the optimal attributes for the coating layer, using voltage applied and deposition time. The coating periods were 2, 4 and 6 minutes, and the concentrations were 4, 7 and 10 g/L, while the voltages were modulated between 20, 40, and 60 volts. In spite of the fact that the metallic medical applications and bone replacement have made substantial and fruitful progress, difficulties still persist. The coating procedures have a significant impact on how well the composite materials work in the biological devices. To improve the properties of composites used in biomedicine, coating them is an essential step. X-ray diffraction (XRD) spectroscopy and scanning electron microscopy (SEM) were used to examine the deposited coatings, and the Zeta potential for suspensions was computed.

9

Evaluation of the mechanical performance of iron- polymethyl methacrylate and polystyrene polymer products based on alumina nanomaterials

Mohamed Muzher Taha, Nawi Sami A., Algailani Hiba M., Alrubaiy Ahmed A.A.G., Mahmoud Adel K., Farman Salem, Mustafa Ali Mundher, Alamiery A.A.

Advances in Science and Technology. Research Journal

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2025

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Vol. 19, no. 3

202--210

EN

In this investigation, alumina (Al₂O₃) nanoparticles were utilized to study the mechanical properties of two polymer nanocomposite systems applied to low-carbon steel substrates. The nanocomposites comprised polystyrene (PS) and polymethylmethacrylate (PMMA) matrices, each incorporating 5 wt.% Al₂O₃ nanoparticles. Tensile tests revealed that the nanocomposites exhibited superior mechanical performance compared to pure polymers. For PMMA-Al₂O₃, tensile properties such as elastic modulus (E), ultimate tensile strength (σₐᵤₗₜ), and strain (eᵤₗₜ) were 2.6326 GPa, 44.52 MPa, and 0.02560, respectively, showing improvements of 16.5% in σₐᵤₗₜ and 33.7% in eᵤₗₜ. Similarly, PS-Al₂O₃ showed σₐᵤₗₜ and eᵤₗₜ improvements of 19.1% and 61.5%, respectively, compared to pure PS. The Scanning electron microscopy (SEM) revealed flocculation and uneven nanoparticle dispersion. At low magnification (1.56 µm), PS-Al₂O₃ particles were well-separated, while higher magnification (11.6 µm) showed aggregation. The average nanoparticle diameters for PMMA-Al₂O₃ and PS-Al₂O₃ were 201.1 nm and 184.6 nm, respectively. Flocculation and low-density interphase, attributed to fewer polymer chain anchoring sites on Al₂O₃ surfaces, reduced the elastic modulus. These findings emphasize the need for advanced blending techniques to achieve uniform nanoparticle distribution and improve polymer-nanoparticle interfacial bonding. Optimized dispersion methods are crucial for enhancing the mechanical properties of Al₂O₃-reinforced nanocomposites.

10

Contribution to manufactured a new thermoplastic biocomposite reinforced with natural fabric of date palm fibers without any treatment

Slimani Faouzi, Ghanmi Ines, Ghanmi Samir, Guedri Mohamed

Advances in Science and Technology. Research Journal

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2025

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Vol. 19, no. 7

302--312

EN

Although significant progress has been made in the production of biocomposites, persistent challenges remain in the processing, distribution and arrangement of natural fibres. These problems stem mainly from the lack of standardised methods for fibre processing, insufficient access to specialised equipment and time-consuming preparation processes. This work breaks new ground by developing a PLA biocomposite reinforced with a fabric of untreated date palm fibres, eliminating costly pre-treatment steps. The digitally controlled hot compression method ensures optimal interfacial adhesion, validated by SEM analysis. The main results of this work reveal a significant improvement in mechanical properties, they show a 24% improvement in Young’s modulus (4.20 GPa) and a 31% increase in tensile strength (80 MPa) with 10% fibers, combined with a 15% reduction in density. Fiber/matrix adhesion, validated by SEM, explains these performances, combined with a reduction in costs and environmental impact. The reproducibility of the processes and the biodegradability of the material make it a sustainable solution for light structural applications. The minor defects identified open up avenues for industrial optimisation.

11

Enhancing microstructural and thermal properties of TiNiPd shape memory alloys through copper addition

Hussain Abid, Khan Afzal, Khan Muhammad Imran, Ur Rehman Saif

Advances in Materials Science

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2025

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Vol. 25, nr 1(83)

66--81

EN

This study explores how the addition of copper (Cu) addition impacts the microstructural and thermal properties of shape memory alloys (SMAs), specifically TiNiPd alloys. Two compositions, 0Cu and 10Cu, were analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), Optical Microscopy (OM) and differential scanning calorimetry (DSC). SEM revealed second-phase precipitates distributed along grain boundaries in both alloys, with sizes ranging from 0.9 to 2.9 μm; however, Cu addition reduced precipitate density without affecting size. The grain size increased significantly from 12.5 μm in 0Cu to 17.5 μm in 10Cu, attributed to decreased nickel content and reduced pinning effects of precipitates. Aging at 600°C and 700°C further influenced precipitate behavior and transformation temperatures, with Cu-containing alloys demonstrating enhanced thermal characteristics. DSC analysis indicated significant increases in transformation temperatures and decreased thermal hysteresis with Cu addition. These results highlight the promise of Cu as a viable substitute for Ni in enhancing the properties of TiNiPd SMAs.

12

Machinability analysis of thin-walled carbon fiber reinforced ceramic composites based on wire electrical discharge machining

Poroś Dariusz, Wiśniewska Magdalena

Zeszyty Naukowe Politechniki Morskiej w Szczecinie

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2024

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nr 77 (149)

5--13

EN

We propose employing wire electrical discharge machining (WEDM) for shaping thin-walled, multidirectional, carbon fiber reinforced silicon carbide (Cf-SiC) composite parts. Ceramic matrix composite Cf-SiC combines the outstanding mechanical properties of the carbon fiber with oxidation, abrasive wear, corrosion resistance, and high strength at the high temperature of the silicon carbide matrix. The impact of time-related electrical discharge machining parameters (pulse ON-time and break OFF-time) on the material removal rate and surface roughness are analyzed. The material removal rate of the Cf-SiC is proved to be 36% lower than that for machined steel grade 55. The high thermal stresses and interaction of the composite accompanying WEDM are also discussed. Furthermore, an alternative mechanism to the WEDM of metals has been investigated and confirmed by a scanning electron microscopy (SEM) analysis. The morphology of the machined Cf-SiC surface demonstrates the dominance of the carbon fibers’ fracture mechanism, both the transverse and longitudinal forms, with interphase detachment over craters and micro-cracks, pitting, and spalling on the SiC matrix. Satisfactory roughness indicators (Sa = 2 µm) are obtained in 3D topography measurements of the Cf-SiC surfaces. Concluding, the WEDM should be considered a good alternative to Cf-SiC abrasive machining when cutting holes, grooves, keyways, splines, and other complex shapes.

13

Application properties and microscopic analysis of elastomer samples cross-linked by gamma radiation

Bonato Jasminka

Zeszyty Naukowe Politechniki Morskiej w Szczecinie

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2024

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nr 78 (150)

15--21

EN

Natural rubber is an important industrial material derived from caoutchouc trees (Hevea Brasiliensis). By chemical composition, it is a polymer material that is mostly cis-1,4-polyisoprene. It falls into the category of elastomers, which enables its wide usage due to its specific characteristics. Polymer materials include plastic, rubber, and glue and are the most important technical materials. Rubbers are used in the production of conveyor belts, shock absorbers, coatings, fenders, engines, and device parts. They are also used in composite materials such as threads, particles, and matrix materials. By analyzing the properties of natural rubber, the subject of the research is defined, i.e., the characterization of natural rubber samples and their connection with macroscopic properties. In accordance with the subject of the research, in this paper, tests are carried out on samples of natural rubber, which are obtained in the form of thin films from latex and cross-linked by gamma radiation. A total dose of 300 kGy is applied to the samples in the state of uniaxial deformation. In this sense, a hypothesis is put forward that involves examining the influence of radiation dose on the morphology of natural rubber samples using scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDX). The investigation aims to emphasize the importance of the method in acquiring a comprehensive characterization of the material samples, which are used both in maritime areas and in other fields of application.

14

Wykorzystanie tomografii komputerowej oraz SEM w ocenie morfologii przekrojów próbek azotanu(V) amonu

Biessikirski Andrzej, Kuterasiński Łukasz, Dworzak Michał, Kolano Malwina, Ruggiero-Mikołajczyk Małgorzata

Przemysł Chemiczny

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2024

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T. 103, nr 7

805--810

PL

Przedstawiono wyniki badań doświadczalnych związanych z analizą powierzchni morfologicznej w przekrojach granul porowaconego i rolniczego azotanu(V) amonu. Ocenę morfologii przeprowadzono z wykorzystaniem SEM oraz tomografii komputerowej. Przekroje próbek azotanu(V) amonu charakteryzowały się strukturą przypomi nająca pumeks. Wykazały występowanie niewielkiej liczby kanałów oraz brak chropowatości powierzchni krystalicznej. W przypadku porowaconego azotanu(V) amonu próbki charakteryzowały się zróżnicowaną budową wynikającą z różnych procesów produkcyjnych. Obie próbki wykazywały dużą liczbę porów, m.in. obecność porów kulistych i wydłużonych. Ponadto w przypadku AN-PP-2 w przekroju próbki widoczna była centralna pustka powietrzna, która nie znajdowała się na żadnym ze skanów dla AN-PP-1. Porowacony azotan(V) amonu charakteryzował się dużą porowatością, rzędu 60-70%, w po równaniu z porowatością rolniczego azotanu(V) amonu (ok. 49%). Przeprowadzone badania BET wykazały, że AN-PP-2 charakteryzował się największą powierzchnią właściwą, ok. 0,5 m²/g, co przy uwzględnieniu mocno rozwiniętej budowy morfologicznej potwierdza wysokie określane przez producenta współczynniki absorpcji.

EN

The morphology of cross sections of porous and agricultural NH₄NO₃ granules was analyzed by scanning electron microscopy (SEM), computed tomography and low-temperature nitrogen sorption. Agricultural NH₄NO₃ showed a pumice-like structure, characterized by a small number of channels and a smooth crystalline surface but samples of prilled NH₄NO₃ showed a significant presence of pores, including spherical and elongated pores. The porosity of prilled and agricultural NH₄NO₃ was 70 and 49%, resp. and BET surface area of both materials was 0.5 m²/g and 0.01 m²/g resp.

15

Effect of low-temperature plasma treatment on rubber properties

Ďurišová Silvia, Pajtášová Mariana, Ondrušová Darina, Janík Róbert, Mičicová Zuzana, Dubec Andrej, Pagáčová Jana, Šulcová Jana, Božeková Slavomíra, Vavro Jan, Klepka Tomasz

Polimery

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2024

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Vol. 69, nr 4

245--253

EN

The effect of the distance (0.5 and 5 mm) and exposure time (10 and 30 s) of the atmospheric plasma on the structure and surface properties (contact angle, adhesion) of unvulcanized rubber was examined. FT-IR and SEM were used to assess the structure. After plasma treatment, a higher intensity of the OH and COO- bands was observed, while the intensity of the bands from methylene groups decreased. SEM showed that plasma significantly reduces the size and number of agglomerates, resulting in a more uniform structure. The plasma distance has a significant effect on the surface properties of the rubber, with a better effect achieved at a smaller distance (0.5 mm). In this case, the rubber character changed from hydrophobic to hydrophilic, which is related to the introduction of oxygen species. A greater plasma distance (5 mm), regardless of the exposure time, resulted in a lower adhesion force. The exposure time had no significant effect on the tested rubber properties.

PL

Zbadano wpływ odległości (0,5 i 5 mm) oraz czasu ekspozycji (10 i 30 s) plazmy atmosferycznej na strukturę i właściwości powierzchniowe (kąt zwilżania, adhezja) niewulkanizowanej gumy. Do oceny struktury stosowano FT-IR i SEM. Po obróbce plazmą zaobserwowano większą intensywność pasm pochodzących od grup OH i COO-, natomiast intensywność pasm pochodzących od grup metylenowych zmniejszyła się. Metodą SEM wykazano, że plazma znacząco zmniejsza wielkość i liczbę aglomeratów, czego efektem jest bardziej jednorodna struktura. Odległość plazmy ma istotny wpływ na właściwości powierzchniowe gumy, przy czym lepszy efekt uzyskano przy mniejszej odległości (0,5 mm). W tym przypadku charakter gumy zmienił się z hydrofobowego na hydrofilowy, co jest związane z wprowadzeniem ugrupowań tlenowych. Większa odległość próbki od plazmy (5 mm), niezależnie od czasu ekspozycji, skutkowała mniejszą siłą adhezji. Czas ekspozycji nie miał istotnego wpływu na badane właściwości gumy.

16

The effect of anodic polarization of 304 stainless steel in choline chloride-based DES solvent on its surface morphology and corrosion resistance

Marczewski Marek, Tylus Włodzimierz, Winiarska Juliusz

Ochrona przed Korozją

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2024

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nr 4

96--105

EN

AISI 304 alloy steel was polarized anodically in a deep eutectic solvent based on choline chloride and oxalic acid (1 : 1 molar ratio) at the temperature range of 25–75°C and the current density range of 2.5–45 mA cm−2. No improvement in visual parameters (gloss) was observed with increasing temperature. That was due to the formation of numerous pits on the surface as evidenced by SEM microscopy. AFM showed at lower temperatures the evenly distributed shallow pits, while at higher temperatures – less numerous but larger ones. XPS and ICP-AES analysis showed that the anodic polarization process increased the content of oxidized chromium on the surface and indicated high degree of iron leaching from the material. Morphology of this passive layer, which thickness was calculated to 3.3 nm, was characterized by uniform mixture of Cr(III) oxide and hydroxide. In contrast to chemically etched steel, polarization in DES produced surface layer enriched with Cr2O3 (56% instead of 28% total share) with lower share of Cr(OH)3 (41% instead of 70% total share). Anodic polarization process in proposed DES was responsible for a slight increase in corrosion resistance of 304 steel.

PL

Stal stopową AISI 304 poddano polaryzacji anodowej w rozpuszczalniku eutektycznym złożonym z chlorku choliny i kwasu szczawiowego (1 : 1 molowo) w temperaturze 25–75°C i przy gęstości prądu 2,5– 45 mA cm−2. Nie zaobserwowano poprawy połysku wraz ze wzrostem temperatury procesu ze względu na powstanie licznych wżerów na powierzchni, widocznych za pomocą mikroskopii SEM. Analiza AFM wykazała, że w niższych temperaturach wżery są płytkie i równomiernie rozmieszczone, a w wyższych są większe i mniej liczne. Analizy XPS i ICP-AES ujawniły, że na skutek polaryzacji anodowej wzrasta ilość utlenionego chromu w powierzchni stali, czemu towarzyszy nadmierne roztwarzanie żelaza ze stopu. Morfologia wytworzonej warstwy pasywnej, o grubości około 3,3 nm, to jednorodna mieszanina tlenku i wodorotlenku Cr(III). W porównaniu z trawioną chemicznie stalą polaryzacja anodowa w DES skutkuje wytworzeniem warstwy powierzchniowej wzbogaconej w Cr2O3 (56% zamiast 28% zawartości) i z mniejszym udziałem Cr(OH)3 (41% zamiast 70%). Proces polaryzacji anodowej stali 304 w zaproponowanym DES przyczynił się do poprawy odporności na korozję.

17

Review of the possible application of laboratory testing techniques for corrosion protection of steel structures

Kunce Izabela

Ochrona przed Korozją

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2024

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nr 8

220--226

EN

The article includes examples of problems with the corrosion protection of steel structures after a few or several years of operation and presents selected laboratory testing techniques used during technical assessments. The research techniques used included infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). These enabled the following questions to be answered: whether the paint was applied according to the required technology, whether a conversion coating was applied before the powder coating, why a correctly applied zinc coating did not provide sufficient corrosion protection for the fasteners of the steel structure. The paper also details other applications of the presented research methods, not only in the field of performing technical expert reviews, but also in testing systems used in the corrosion protection of steel structures.

PL

W artykule opisano przykłady problemów z zabezpieczaniem antykorozyjnym konstrukcji stalowych po kilku lub kilkunastu latach eksploatacji obiektów oraz przedstawiono wybrane laboratoryjne techniki badawcze wykorzystywane podczas wykonywania ekspertyz technicznych. Zastosowano następujące metodyki badawcze: spektroskopię w podczerwieni (FTIR), skaningową mikroskopię elektronową (SEM) oraz spektroskopię promieniowania rentgenowskiego z dyspersją energii (EDS). Pozwoliło to uzyskać informacje, czy zastosowano farbę zgodną z wymaganą technologią, czy naniesiono powłokę konwersyjną przed malowaniem proszkowym, a także dlaczego poprawnie wykonana powłoka cynkowa nie była wystarczającym zabezpieczeniem antykorozyjnym elementów złącznych konstrukcji stalowej. W pracy wyszczególniono również inne możliwości zastosowania przedstawionych metodyk badawczych, nie tylko w zakresie wykonywania ekspertyz technicznych, lecz także w obszarze badań systemów stosowanych w ochronie antykorozyjnej konstrukcji stalowych.

18

The effect of glass fibers on selected properties of autoclaved sand-lime materials

Jasińska Iga, Dachowski Ryszard, Jaworska-Wędzińska Monika

Materiały Budowlane

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2024

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nr 9

26--31

EN

The aim of the study was to determine the effect of zirconia-coated (AR) glass fibers, with a length of 24 mm, on selected properties of autoclaved lime-sand samples, such as density, water absorption, and compressive strength. Microstructure observations were also conducted using SEM. The research was carried out using fibers with a mass content ranging from 1% to 5%. The obtained results provided the basis for concluding that samples containing 1 – 3% zirconia-coated glass fibers by mass exhibit higher compressive strength compared to the reference samples, and they indicate the direction for further research.

PL

Celem badań było określenie wpływu zawartości włókien szklanych z powłoką cyrkonową (AR) o długości 24 mm, na wybrane właściwości autoklawizowanych próbek wapienno-piaskowych, tj. gęstość, absorpcja wody i wytrzymałość na ściskanie, wykonanych na bazie mieszanki wapienno-piaskowej. Dokonano również obserwacji mikrostruktury za pomocą SEM. Badania przeprowadzono z użyciem włókien, których udział w masie wynosił od 1 do 5%. Otrzymane wyniki badań dały podstawę do stwierdzenia, że próbki zawierające w masie 1 – 3% włókien szklanych z powłoką cyrkonową wykazują wyższą wytrzymałość na ściskanie w odniesieniu do próbek referencyjnych, oraz wskazują kierunek dalszych badań.

19

Impact of Change Orders on Decreasing Labor Productivity in Road Construction Projects (Approach using Structural Equation Modeling)

Waty Mega, Sulistio Hendrik

Management and Production Engineering Review

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2024

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Vol. 15, No. 4

1--12

EN

Change order is the main factor of labor productivity decline in small scale electrical projects in the United States due to presence variables. Preliminary research on labor productivity in Malaysian infrastructure projects with six latent variables using SEM has been conducted on small projects, such as electricity and infrastructure. Therefore, this research aimed to determine the impact of change orders on large and small scale projects of labor productivity in Indonesia. Data were collected through interviews and questionnaires distribution with a return rate of 700 respondents. The collected data were processed using factor analysis and SEM. The result showed that the impact of change orders on the decline in labor productivity in Indonesia led to four latent variables with 15 indicators.

20

Striking the Balance: How Workplace Flexibility Enhances Engagement and Performance of Employees working in Public and Private settings

Parveen Musrrat, Rizq Abrar Talal

Management

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2024

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Vol. 28, no. 2

33--69

EN

This study investigates the relationships between workplace flexibility, employee engagement, and performance of employees working in public and private settings. The purpose is to understand how flexible work arrangements influence employee engagement and overall performance across various industries. This research was conducted using a descriptive quantitative method. A structured questionnaire was used to collect data from 400 employees across finance, technology, healthcare, and manufacturing industries. The measurement model’s reliability was evaluated using the partial least square (PLS) structural equation modeling (SEM) approach (see table 3). Cronbach alpha (α) and composite reliability (CR) values were used. A prognosis model evaluation shows that all of the variables have SRMR values of 0.082 and NFI values of 0.914, suggesting that the model accurately matches with the experimental data. The Q2 predict value for employee performance (EP) of 0.352 shows excellent predictive relevance with a significant impact size. In comparison, the Q2 predict predictive value for Employee Engagement (EENG) is 0.185, indicating good predictive relevance with a modest impact size. These Q2Predict values are higher than the required minimum threshold of 0.00, indicating that the model is highly predictive for each variable. Furthermore, the Q2 effect sizes for EENG and EPC show that they have a significant impact on the endogenous variable (WPFX). SmartPLS 3.3.9 used the PLS algorithm as well as the bootstrapping approach to evaluate the presented hypothesis. Table 6 shows the beta values that demonstrate the intensity and significance of the positive link between the dependent and independent variables, where employee engagement acts as both a moderator and mediator. By including both mediation and moderation in the same model, you can gain a more comprehensive understanding of how workplace flexibility impacts employee performance, considering the mediating role of employee engagement and the moderating effect of its level. In addition to the above analysis, demographic factors are tested by Manova.