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1

Characterization of EN-AW-6061-O–graphite nanoflake composites for enhanced mechanical properties using multi-pass friction stir processing

Patil Namdev Ashok, Pedapati Srinivasa Rao, Kakkeri Shrishail, Pedapati Santoshi

Advances in Materials Science

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2025

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Vol. 25, nr 3(85)

5--17

EN

In this study, graphite (Gr) nano flakes dispersion with increasing number of passes (1, 2, and 3) inside the resultant aluminium ENAW-6061-O-Gr composites using Friction Stir Processing (FSP) has been accomplished successfully. The objectives were to embed the Gr nanoflakes inside ENAW-6061-O-Gr composites, investigate the effect of number of FSP passes on the mechanical properties of aluminium 6061/graphite composites. The ENAW-6061-O-Gr composite samples were evaluated with tensile tests and elemental analysis through SEM with EDX and mapping. The dispersion and presence of graphite particles is confirmed. Multi-pass FSP improved the tensile strength of the ENAW-6061-O-Gr composites. The UTS of C3-Composite processed with three passes is 153.65 MPa, that is 24% of improvement compared to the unreinforced aluminium ENAW-6061-O base metal alloy.

2

Ocena możliwości wykorzystania węgla z pirolizy metanu jako biokomponentu smarów plastycznych

Skibińska Agnieszka, Sacha Dariusz, Krasodomski Wojciech, Wojtasik Michał

Rynek Energii

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2024

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Nr 3

73--77

PL

Przeprowadzono w laboratorium proces pirolizy metanu z wytworzeniem wodoru oraz węgla. Uzyskany materiał węglowy wykorzystano jako dodatek funkcyjny w smarach plastycznych, poprawiający właściwości smarne i przeciwzużyciowe. Zastosowano smary litowe, jako najpowszechniej stosowane. Porównano właściwości uzyskane w badaniu aparatem czterokulowym do właściwości analogicznych próbek smarów zawierających grafit naturalny.

EN

Evaluating the lubricating and anti-wear properties of lithium-based lubricating greases, determined in accordance with the method of PN—EN 20623, it can be concluded that the addition of both carbon and graphite allows similar results. Carbon obtained by methane pyrolysis, after appropriate grinding, can be successfully used instead of crystalline natural graphite as an additive for lubricating grease.

3

Wstępne badania nad oceną parametrów mechanicznych ochronnych materiałów tekstylnych powlekanych pastą poliuretanową z dodatkiem grafitu i nanorurek węglowych

Irzmańska Emilia, Boczkowska Anna, Żyłka Emilia, Jurczyk-Kowalska Magdalena, Strycharz Kamila, Szroeder Paweł

Przemysł Chemiczny

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2024

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T. 103, nr 1

117--123

PL

Omówiono wpływ grafitu oraz nanorurek węglowych dodanych do pasty powlekającej materiał tekstylny na podstawowe parametry mechaniczne. Przedstawiono wyniki badań odporności na przecięcie metodą TDM i coup test oraz odporności na ścieranie dla otrzymanych powlekanych materiałów tekstylnych.

EN

Meta-aramid fibers were coated with polyurethane paste mixed with graphite and C nanotubes in various configurations. Cutting and abrasion resistance as well as SEM anal. of composites were performed. The effect of the applied coating on the mech. parameters was examined.

4

Wpływ zawartości grafitu na właściwości mechaniczne warstw hybrydowych Ni-P/Si3N4/grafit osadzonych na stopie AW-7075 metodą redukcji chemicznej

Czapczyk Kazimierz

Przemysł Chemiczny

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2024

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T. 103, nr 1

86--92

PL

Przedstawiono wpływ obecności grafitu jako fazy dyspersyjnej na właściwości mechaniczne warstw hybrydowych Ni-P/Si₃N₄/grafit, które osadzono metodą redukcji chemicznej na stopie glinu AW-7075. Wykonano badania morfologii powierzchni warstw metodą mikroskopii świetlnej i skaningowej. Dalszą część pracy stanowiły badania mechaniczne, czyli pomiary mikrotwardości warstw oraz ich adhezji do aluminiowego podłoża, a także analizy wpływu obecności grafitu na podstawowe właściwości materiału powłokowego. Zbadano próbki ze stopu AW-7075, na których osadzono metodą bezprądową powłoki hybrydowe i porównawczo nanokompozytowe o różnym składzie chemicznym, modyfikowanym zawartością faz dyspersyjnych.

EN

The mech. and adhesive properties of Ni-P/Si₃N₄ and Ni-P/Si₃N₄/graphite coatings deposited using the electroless method on the AW-7075 Al alloy were compared. Coatings with different chem. compns., modified by the content of dispersion phases (Si₃N₄ and graphite), were used. Microhardness and adhesion of the layers to the Al substrate were measured. The impact of the presence of graphite on the basic properties of the coating material was analyzed. The surface morphol. of the layers was examined using light microscopy and SEM. The incorporation of Si₃N₄ and graphite into the coating material resulted in a several-fold increase in the microhardness of the surface layer compared to the Al alloy.

5

Reflektografia w bliskiej podczerwieni jako proste narzędzie do ujawniania nieczytelnych zapisów wykonanych na różnych podłożach celulozowych

Kozielec Tomasz, Kozielec Joanna

Przegląd Papierniczy

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2024

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R. 80, nr 11

616--621

PL

W publikacji omówiono przykłady użycia bliskiej podczerwieni do odczytywania zakrytych lub mało widocznych tekstów, notatek wykonanych przy użyciu ołówków grafitowych w badaniach konserwatorskich. Osiągnięcie zadowalających efektów uczytelnienia jest możliwe ze względu na obecność w ich składzie chemicznym węgla pierwiastkowego. Zagadnienia zilustrowano przykładami zapisków wykonanych na różnych podłożach celulozowych. Wykazano również przydatność promieniowania podczerwonego do przenikania przez warstwy barwników niebieskich zasłaniających teksty znajdujące się pod nimi.

EN

The publication discusses examples of the use of near-infrared radiation to read covered or poorly visible texts, notes made with graphite pencils in conservation research. Achieving satisfactory results is possible due to the presence of elemental carbon occuring as their basic ingredient. The issues are illustrated with examples of notes found on various cellulose substrates. The suitability of infrared radiation to penetrate the layers of blue dyes obscuring the texts below is also demonstrated.

6

The analysis of electrode material efficiency in hydrogen production through electrolysis from seawater solution

Kaensakol Rungchai, Srisiriwat Anuchart, Srisiriwat Nawadee

Przegląd Elektrotechniczny

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2024

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R. 100, nr 1

45--48

EN

Where there is a shortage of fresh water but abundant solar and wind power is available during the day, seawater electrolysis to produce hydrogen used as fuel for fuel cells to generate electricity at night is an attractive alternative. The electrode is one of the key parts of the seawater electrolysis process. Moreover, this study focused on the commercial electrodes as a preliminary study to see if it was possible to use the low-cost and easy-to-access materials. Four electrodes, including graphite, brass, stainless steel, and steel, were used to study the effects of electrode materials on hydrogen production via seawater electrolysis. In addition, the effects of reaction times on operating parameters such as voltage, current, and pH were reported. Hydrogen production using graphite electrodes showed higher hydrogen production than that using metal electrodes. For 360-min reaction times, the hydrogen production using graphite, stainless steel 316, steel, and brass electrodes decreased from 1.46 to 0.7, 0.74 to 0.62, 0.62 to 0.52, and 0.24 to 0.01 ml min-1 cm-2 at the current density of about 150, 4 - 24, 110, and 110 mA/cm2, respectively. However, when the power input to the electrolysis process was considered to compare the efficiency of hydrogen production per power input, it was found that graphite produced more hydrogen than other materials, but after 60 min, stainless steel gave the highest hydrogen production. At pH > 7.5, the OCl- is the main cause of electrode corrosion, resulting in decreasing hydrogen production.

PL

Tam, gdzie brakuje słodkiej wody, ale w ciągu dnia dostępna jest duża ilość energii słonecznej i wiatrowej, atrakcyjną alternatywą jest elektroliza wody morskiej w celu wytworzenia wodoru wykorzystywanego jako paliwo do ogniw paliwowych wytwarzających energię elektryczną w nocy. Elektroda jest jedną z kluczowych części procesu elektrolizy wody morskiej. Co więcej, w ramach tego badania skupiono się na elektrodach dostępnych na rynku, aby sprawdzić, czy możliwe jest zastosowanie tanich i łatwo dostępnych materiałów. Do zbadania wpływu materiałów elektrod na produkcję wodoru w procesie elektrolizy wody morskiej wykorzystano cztery elektrody, w tym grafit, mosiądz, stal nierdzewną i stal. Ponadto opisano wpływ czasów reakcji na parametry operacyjne, takie jak napięcie, prąd i pH. Produkcja wodoru przy użyciu elektrod grafitowych wykazała wyższą produkcję wodoru niż przy użyciu elektrod metalowych. Dla czasów reakcji 360 min produkcja wodoru przy użyciu elektrod grafitowych, Stal nierdzewna 316, stalowych i mosiężnych spadła z 1,46 do 0,7, 0,74 do 0,62, 0,62 do 0,52 i 0,24 do 0,01 ml min-1 cm-2 przy gęstości prądu odpowiednio około 150, 4 - 24, 110 i 110 mA/cm2. Jednakże, gdy wzięto pod uwagę moc wejściową procesu elektrolizy w celu porównania wydajności produkcji wodoru na pobór mocy, stwierdzono, że grafit wytwarza więcej wodoru niż inne materiały, ale po 60 minutach stal nierdzewna dała największą produkcję wodoru. Przy pH > 7,5 OCl- jest główną przyczyną korozji elektrod, powodując zmniejszenie wytwarzania wodoru.

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Electroadsorptive graphite electrode material for desalination of brackish water using capacitive deionisation (CDI) technique, DC-DC system

Chudjuarjeen S., Yoosamran A.

Journal of Achievements in Materials and Manufacturing Engineering

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2024

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Vol. 124, nr 1

34--41

EN

Purpose: The Chao Phraya River is the main river in the central region. It is essential for consumption, agriculture, industry, and ecosystem conservation. In addition, in the area along the Chao Phraya River, there is agriculture, and industry is a source of conservation for many ecosystems. The support of brine from the sea has influenced the sea. The research aims to find the optimum conditions for applying the eelectro-adsorption technique to reduce salinity of the brackish water that can be used in agriculture. Graphite-type electrodes that are easily available and do not require surface treatment are used. Design/methodology/approach: The research aims to reduce the salinity value of brackish water salinity by DC to DC converter electro-sorption of the sample (790 μS.cm-1) with graphite electrode measuring the reduced electrical conductivity. The variables of salinity reduction, electric potential, temperature, and solution stirring have been studied. Removing ions from electrodes involves ultrasonic vibration and temperature. The important reason that graphite electrodes are used in electrosorption is that graphite is a good conductor. The structure of graphite is such that it has many electrons floating freely between the different layers. Findings: The research found that graphite electrodes could absorb electricity by controlling the electric potential (Charging) at 2.0 V for 25 min and at a temperature of 500C without stirring the solution while absorbing ions. It can reduce the salinity to 777 μS.cm-1, representing 1.64%. The optimum condition for washing electrodes used for 15 min at 2.0 V electrode potential for regeneration was washing electrodes without applying electrode potential (Discharge) in high-temperature water and with ultrasonic vibration. It can effectively wash off ions from the surface of graphite electrodes. Research limitations/implications: The ion adsorption of graphite electrodes was only electrical adsorption. Originality/value: The graphite materials have electrosorption properties at low potential and can be readily renewed by discharging the potential. They do not require surface treatment.

8

Modification Graphite of Waste Batteries by Phosphotungstic Acid and Using as Photocatalyst for Methylene Blue Degradation

Jabbar Wisam Abdalhusain, Jabbar Marwa F. Abdul

Ecological Engineering & Environmental Technology

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2024

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Vol. 25, iss. 8

297--307

EN

In photocatalysis water treatments, Heteropoly acids impact is most used to realize effective separation of photogenerated carriers for active degrade organic pollutants. Here, a type of Heteropoly acids used as photocatalyst was prepared, (GHPT) consisted of phosphotungstic acid (PTA) with graphite prepared from a dry battery column and reactivated with hydrochloric acid (GH). Used assays (x-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), BET surface area, energy dispersive x-ray (EDS) and element mapping images) were used to demonstrate the properties, composition, and components of the GHPT. To evaluate the catalytic activity of decomposition of methylene blue (MB) using LED light. The rate of MB decomposition can be affected by the type of catalyst, initial concentration of MB dye, removal time, catalyst dose, and pH. GHPT has many advantages for its practical application, through its properties as a photocatalyst in terms of composition and components in the presence of light. The best removal percentage under the best conditions was 99.74 and total organic carbon analysis (TOC) percentage was 88.12 the at a concentration of 1 g/L of catalyst, an initial concentration of 25 ppm MB of MB, an illumination time of 180 minutes and a pH of 10.

9

Effect of Cu Addition Above the Solubility Limit on Microstructure Formation and Cu Segregation in 800 MPa Grade Ductile Cast Iron During Solidification

Shin Sang-Yun, Ha Seong-Ho, Kim Dong-Hyuk, Choi Jaegu

Archives of Metallurgy and Materials

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2024

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Vol. 69, iss. 2

425--428

EN

In this study, the effect of 3 mass%Cu additions on microstructure formation and Cu segregation in 800 MPa grade ductile cast iron during solidification was investigated. The calculated phase diagram showed that after the addition of 3 mass%Cu, the Cu phase with a negligible amount appeared below 1000°C, and most Cu was included in the matrix. Based on optical microstructure, after the addition of 3 mass%Cu, the size of graphite nodules became finer, and the microstructure rarely had an area with α-ferrite. Image analysis showed that the fraction of pearlite increased significantly, indicating that Cu greatly promoted the formation of pearlite. Compositional analysis by scanning electron microscopy indicated that the pearlitic area also contained approximately 3 mass%Cu, which corresponds to those of primary and secondary austenite calculated. A small and bright phase particle containing a large amount of Cu was observed at the interface of graphite and matrix.

10

Usage of the Cast Iron Cylindrical Liner inan Automobile Engine Block

Orłowicz A., Radoń M., Lenik M., Wnuk G.

Archives of Foundry Engineering

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2024

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Vol. 24, iss. 2

159--163

EN

This study addresses the issues related to the quality of the connection between cast iron liners and inserts in a pressure die-cast automotive engine block, along with the macro and micro wear of the cylinder bearing surface. it was found that the commonly used HPDC high-pressure casting technology of Al-Si alloy engine blocks with cast iron liners, in which the cylinder liner is then recreated, does not ensure their metallic connection. The micro-gap created there becomes thicker as the engine is used, which worsens the conditions for heat dissipation from the sleeve to the block. Locally, on the surface of the cylinder bearing surface, reductions in honing effects and longitudinal cracks were observed. The presented literature mechanism of micro wear of the cylinder bearing surface, dependent on the morphology of graphite segregations, was confirmed. The mechanism of creating micro-breaks in the area of phosphoric eutectic and graphite precipitation occurrence was presented, initiated by the formation of microcracks in the eutectic and delaminations at the eutectic-matrix boundary.

11

The effect of graphite flake diameter on the resistance to thermal shock, microstructure and mechanical properties of silicon carbide nanomaterials

Mahmood Mohammed H., Khalaf Wekar M., Azeez Kafel

Journal of Theoretical and Applied Mechanics

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2023

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Vol. 61 nr 4

783--791

EN

To ascertain the impact of graphite flake diameter on the microstructure and mechani- cal properties as well as resistance to thermal shock, graphite flakes of various diameters have been added to zirconium dibromide (ZrB2) 20 vol.% nano-silicon carbide (SiC) 20 vol.% graphite (ZSnpG) ceramics. The objective of this study is to investigate the effect of graphite flake diameter on silicon carbide nanomaterials. The study aims to identify a strategy for achieving high comprehensive performance of ZrB2-based ceramics incorporating graphite for future research on ultra-high temperature ceramics (UHTCs). The dispersion of mea- surements has been conducted by combining a solid powder with ethanol at various mass fractions. The results demonstrated that, while no changing fracture toughness considerably, the relative density and flexural strength of ZSnpG ceramics initially increased and then de- clined with graphite diameter increasing. The micro-crack length reduction due to residual thermal stress, appearance of silicon carbide nanoparticles within granulation, and manage- ment of graphite distribution all contributed significantly to the improvement of flexural strength ZSnpG ceramics. According to the computed thermal shock parameters, ZSnpG ceramics fracture propagation was constrained by graphite with a larger starting diameter and prevented with a finer starting diameter.

12

Study on Electromagnetic Properties of Graphite/Graphene/Silver-Coated Copper Powder Monolayer Coated Composites

Liu Yuanjun, Han Xiaohui, Bao Wenli, Ding Xiongwei, Zhao Xiaoming

Fibres & Textiles in Eastern Europe

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2023

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Vol. 31, no. 1

83--90

EN

With the rapid development of electronic technology and military techniques, electromagnetic protection materials are becoming more and more significant to people. Harmful electromagnetic radiation not only affects the normal operation of electronic equipments and military security, but also has a serious impact on human health. At present, using absorbing and shielding materials are effective means to reduce the harm of electromagnetic waves. In this project, graphite, graphene and silver-coated copper powder coated composites were prepared using PU-2540 polyurethane and adopting a coating process for the substrate on plain polyester/cotton fabric. The controlled variable method was used to prepare and study the electromagnetic properties of single-layer coating composites with different functional particle contents. The result showed that within the frequency range of 0.01GHz~1.0GHz, when the total mass of functional particles was 48% relative to that of the polyurethane, the value of the real part of the dielectric constant of the sample remained the largest and its polarization ability was the strongest. Within the frequency range of 0.08GHz~1.0GHz, when the content of functional particles was 24% relative to that of the polyurethane, the value of the imaginary part of the dielectric constant and the loss of the tangent value of the sample kept the maximum, and the loss and attenuation ability with respect to electromagnetic waves were both the strongest. Within the frequency range of 1.3GHz~2.0GHz, when the content of functional particles was 36% relative to that of the polyurethane, the value of the reflection loss of the sample was -26.93dB, and the minimum value of the reflection loss was obtained at a frequency of 1.6GHz, at the moment of which, the absorbing property of the sample was the best.

13

The Formation, Properties and Use of Dispersed Iron-Graphite Metallurgical Waste

Dan Leonid, Maslov Vladimir, Trofimova Larysa, Cios Grzegorz

Journal of Casting & Materials Engineering

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2022

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Vol. 6, no. 4

81--92

EN

Dispersed wastes containing graphite, iron, and its oxides, getting into the air and accumulating in landfills, cause serious harm to human health and the environment. Moreover, even if the issue of the localization of these wastes has been solved successfully, their disposal has not yet been fully organized. In the present study, a systematic analysis of the dispersed iron-graphite waste (IGW) conditions for the formation at metallurgical enterprises, their structure, and their properties were carried out. In this case, special attention is focused on the electrophysical properties: specific saturation magnetization and volume resistivity. The presence of magnetic properties in IGW, combined with low electrical resistivity, makes IGW a promising and inexpensive raw material for obtaining cheap composite materials with radio shielding and radio absorbing properties in the microwave range. As a result of the research, effective ways of improving the magnetic properties of IGW by high-temperature treatment were obtained. The practical result of the research was the development and implementation of a technological scheme of dispersed IGW complex processing, which makes it possible to solve a twofold task – to exclude the ingress of iron-graphite wastes into the environment and to obtain a cheap material for protection against microwave radiation.

14

A study on mechanical and wear behaviour of graphite filled sisal-glass-epoxy hybrid composites

Suresh Kumar Devendrappa, Sanjeevamurthy, Mallesh Goud, Pavankumar Ravikumar, Vasanth Kumar Hasthinapura Seena Naik

Composites Theory and Practice

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2022

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R. 22, nr 2

106--113

EN

In recent years, advancements in development of composite materials can be distinctively observed and taking ecological factors into account, researchers are currently working on the development of natural fibre composites for various applications. The current work concentrates on assessment of the mechanical and wear characteristics of sisal-glass (natural and synthetic) epoxy hybrid graphite filled composites. A comparative characteristic study was performed in the study between synthetic (glass) and natural (sisal) FRP composites and it was found that graphite filled FRP composites exhibit excellent tensile properties, flexural modulus enhanced by 35.2%, the hardness and impact strength were improved with the addition of graphite filler. Statistical analysis was conducted using the design of experiments with the help of ANOVA software. From the tribology tests, it was noticed that the COF and wear loss of the composites with the natural reinforcement are comparatively higher than that of the synthetic fibre. It is evident from ANOVA and regression analysis that the reinforcement has 57.99% influence on the wear rate. Due to increased environmental consequences, natural FRP composites are recommended to be used in as automotive brake friction material and aerospace body parts.

15

Evaluation of Wear Mechanisms of Graphites Used for Crystallisers for Continuous Casting

Brudny Anna, Kulasa Joanna, Juszczyk Barbara, Myalski Jerzy, Roskosz Stanisław, Wycisk R., Kwaśniewski Paweł, Strzępek Paweł, Poręba Marek

Archives of Foundry Engineering

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2022

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Vol. 22, iss. 4

109--115

EN

This paper presents the results of research concerning the evaluation of tribological properties of graphite materials used, among others, for crystallisers for continuous casting of non-ferrous metals and their alloys. Graphite materials differing not only in their physical properties but also in the technology of their production were selected from a wide range of commercially available products. Wear resistance investigations of the tested graphite materials were carried out on a pin-on-disc tribometer under technically dry friction conditions on a sliding distance of 1000 m. A constant load but variable speed was used in the tests. The mean value of the coefficient of friction and the wear of the material were determined based on the tribological tests carried out. It was observed that as the speed increases, the average value of the coefficient of friction decreases, while the wear increases. A microstructural analysis of the wear track showed that the friction mechanism depends mainly on the graphite formation technology, which is related to the microstructure of the tested materials, and to a lesser extent to their physical and mechanical properties. Varying the speed values made it possible to trace changes in the wear mechanism, on the basis of which it is possible to predict the durability and reliability of graphite crystalliser operation.

16

Influence of extruder plasticizing systems on the selected properties of pla/graphite composite

Kaczor Daniel, Bajer Krzysztof, Domek Grzegorz, Madajski Piotr, Raszkowska-Kaczor Aneta, Szroeder Paweł

Acta Mechanica et Automatica

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2022

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Vol. 16, no. 4

316--324

EN

Twin-screw extrusion is a crucial method for the direct inserting of carbon micro- and nanomaterials into a polymer matrix using a dry procedure. The study aimed to determine the influence of the parameters of the twin-screw extruder plasticizing system on the dispersion homogeneity and distribution of graphite filler in the polylactide polymer matrix and overall quality of the composite. As a filler, a graphite micropowder with a 5 μm lateral size of platelets was used at concentration of 1 wt.%. Three configurations of screws with different mixing intensity and various types segments were considered in the extrusion experiments. Morphology and chemical structure of the obtained composites were examined using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy – attenuated total reflectance (FTIR-ATR) and Raman spectroscopy. Differential scanning calorimetry (DSC) and melting flow rate measurements (MFR) were used to asses thermal and rheological properties of the composites. Samples of the polylactide/graphite composites were also subjected to mechanical tests. The results show that the selection of the mechanical parameters of twin-screw extruder plasticizing system plays a key role in the preparation of the homogeneous PLA/graphite composites. Incorrect selection of the screw geometry results in poor mixing quality and a significant deterioration of the mechanical and thermal properties of the composites. Optimised mixing and extrusion parameters can be the starting point for the design of efficient twin-screw extruder plasticizing system for fabrication of PLA composites with carbon nanotube and graphene fillers.

17

Influence of laser texturing on tribological properties of DLC coatings

Radek Norbert, Tokar Dorota, Kalinowski Artur, Pietraszek Jacek

Production Engineering Archives

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2021

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Vol. 27, Iss. 2

119--123

EN

The work presents the use of laser texturing of DLC coatings to improve tribological properties. The coatings were applied by the PVD method to the rings made of 4H13 steel. The surface texturing was = 343 nm.performed with the TruMICRO 5325c picosecond laser with the radiation wavelength The surface microstructure analysis, surface microgeometry and microhardness measurements and tribological tests were carried out. The problem presented in the paper can be used to extend the knowledge of the areas of application of DLC coatings, especially in sliding friction pairs.

18

High-temperature carbothermal dephosphorization of Malaysian monazite

Udayakumar Sanjith, Sheikh Abdul Hamid Sheikh Abdul Rezan, Baharun Norlia, Pownceby Mark

Physicochemical Problems of Mineral Processing

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2021

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Vol. 57, iss. 6

140--155

EN

High-temperature carbothermal reduction experiments with graphite powder were conducted to assess the dephosphorization behavior of Malaysian monazite concentrate. Thermodynamic analysis of the possible dephosphorization reactions was conducted to evaluate the feasibility of the carbothermal reduction of the monazite phases. The effects of temperature, particle size, and monazite to carbon ratio were then investigated under different conditions. The carbothermal reduction experiments were conducted based on the Taguchi design method, and up to 97% of phosphorous removal was achieved under optimized conditions. The optimal conditions for dephosphorization were determined as; a reduction temperature of 1350 °C, a particle size of -75 μm, and monazite to carbon molar ratio of 0.3. Microstructural and phase characterization of the dephosphorized products revealed that CeO2, Nd2O3, La2O3, and Pr2O3 oxide phases were prominent, and no residual peaks of monazite remained in the reduced products. The information gained from the study can aid in the design of a suitable post-dephosphorization hydrometallurgical treatment for exploiting Malaysian monazite as a local source of REEs.

19

Study of the Dielectric Properties and Conductivity of Double Coated Glass Fibre Felt Composites

Liu Yuanjun, Wang Caixia, Ma Yiping, Liu Yanyan, Wu Haiying, Zhao Xiaoming

Fibres & Textiles in Eastern Europe

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2021

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Vol. 29, no. 4 (148)

75--80

EN

Graphite/talcum powder double-coated glass fibre felt composites were prepared using glass fibre felt as the base material, graphite as the surface absorbing agent, talcum powder as the underlying absorbing agent, epoxy resin E44 as the adhesive and low molecular 650 polyamide as the curing agent. The influences of the surface graphite content and underlying talcum powder content on the dielectric properties and conductivity of glass fibre felt composites were the main focus of the investigation. Results showed that when the frequency is less than 103 Hz, the values of the real and imaginary parts of the dielectric constant for double-coated glass fibre felt composites are largest when the surface graphite content is 50%. When the frequency is larger than 106 Hz, the value of the real part of the conductivity is largest when the graphite contents are 40% and 50%. When the frequency is less than 104Hz, the real part of the dielectric constant of the glass fiber mat composites is the largest when the talc content is 40%, and when talc content is 60%, the imaginary part of dielectric constant of glass fiber mat composites is the largest. The maximum loss tangent value for the composites occurs when the talcum powder content is 40%. When the frequency is larger, the value of the real part of the conductivity increases gradually.

PL

W pracy przygotowano podwójnie powlekane kompozyty filcu z włókna szklanego w postaci grafit/talk. Użyto filcu z włókna szklanego jako materiału bazowego, grafitu jako powierzchniowego środka pochłaniającego, talku jako podstawowego środka pochłaniającego, żywicy epoksydowej E44 jako kleju i poliamidu 650 o niskiej masie cząsteczkowej jako środek utwardzającego. Głównym przedmiotem badań było określenie wpływu zawartości grafitu powierzchniowego oraz zawartości proszku talku na właściwości dielektryczne i przewodność kompozytów z filcu z włókna szklanego. Wyniki wykazały, że gdy częstotliwość jest mniejsza niż 103 Hz, wartości części rzeczywistej i urojonej stałej dielektrycznej dla podwójnie powlekanych kompozytów z filcu z włókna szklanego są największe, gdy zawartość grafitu powierzchniowego wynosi 50%. Gdy częstotliwość jest większa niż 106 Hz, wartość rzeczywistej części przewodnictwa jest największa, gdy zawartość grafitu wynosi 40% i 50%. Maksymalna wartość tangensa strat dla kompozytów występuje, gdy zawartość talku wynosi 40%. Gdy częstotliwość jest większa, wartość rzeczywistej części przewodnictwa stopniowo wzrasta.

20

Graphite-glass screen-printed film electron emitters

Matusiak Tomasz, Laszczyk Karolina

Przegląd Elektrotechniczny

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2020

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R. 96, nr 5

75--78

EN

In this paper, we present the technology and principle performance of film electron emitters made of graphite-glass composite paste using screen printing. As a result, we got working emitters with emission current densities and the turn-on electric field voltage comparable to film electron emitters made of nano-scale carbon composites that were reported in the literature.

PL

W tym artykule prezentujemy technologię i podstawowe charakterystyki pracy warstw emitujących elektrony i wykonanych techniką sitodruku z wykorzystaniem pasty kompozytowej grafitowo-szkłanej. Emitery te osiągnęły gęstości prądów emisji oraz napięcie progowe, przy którym rozpoczyna się emisja, porównywalne do tych, jakie zostały opisane w literaturze naukowej dla materiałów węglowych w nano-skali.