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1

Investigations of technical challenges in compounding of recycled carbon fibers

Hannan Azmin, Seidlitz Holger, Krenz Jonas, Müller Marco

Zarządzanie Przedsiębiorstwem

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2023

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Vol. 26, nr 2

7--12

EN

Carbon fiber reinforced plastics (CFRP) owing to its excellent properties have found its extensive application in various fields ranging from medical to automobile and aerospace industries. This has thereby led to ever-increasing demand of carbon fiber production and as well as resulting in tonnes of carbon fiber wastes in the landfills [5]. Due to the high positive impacts of using carbon fibers, the energy intensive and cost intensive production of virgin fibers and the growing landfills are often overlooked. Hence, the need for recycling and repurposing of carbon fiber wastes have gained the significance at present day. Although various recycling technologies have been developed yet, various challenges are faced with processing of recycled carbon fibers (rCF). Besides, the desired application specific properties are not compromised for high cost and high-energy requirement. Therefore, an overall development of processing rCF is sought from not only a sustainability point but also an economic point [7]. Various efficient recycling technologies are currently operating. The challenges arises in commercializing the recycled fibers after the recycling process. The recycled fibers often require various post-processing of fibers and undergoes fiber degradation. This induces a skeptical mindset for the buyers to introduce the recycled fibers in the material ecosystem. This paper currently discusses the processing challenges of long rCF in a compounding plant. To form a closed loop, the recycled fibers are obtained from the novel thermocatalytic degassing process from the CFRP recycling pioneers in Germany, Global EnerTec AG, Guben. This plant in Guben not only recycles carbon fibers from automotive CFRP wastes but also repurposes the epoxy matrices into secondary energy sources. This paper focuses in investigating the processing of rCF obtained from a 100% recycling technology. The aim is to investigate the possible technical challenges so that the rCF can be repurposed to new product manufacturing. Thereby, addressing the concerns with the development of closed loop circular economy in recycling CFRP wastes.

2

Wzmacnianie konstrukcji taśmami z włókien węglowych (CFRP) na przykładzie remontu wiaduktu M.04 w ciągu alei Prymasa Tysiąclecia w Warszawie

Stępień Mariusz

Mosty

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2023

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nr 1

53-54

PL

Budimex jako główny wykonawca przebudowy stacji Warszawa Zachodnia dokonał remontu wiaduktu w ciągu Al. Prymasa Tysiąclecia w Warszawie – obiekt M.04 w km 3+434 linii nr 1 Warszawa– Katowice. W artykule opisano historię obiektu oraz słuszność wzmocnienia stropu taśmami węglowymi CFRP.

3

The Effect of Chopped Glass and Carbon Fiber Reinforcement on Physical, Mechanical, and Fire Performance of Wood Plastic Composites

Durmaz Sefa, Aras Uğur, Avci Erkan, Mengeloğlu Fatih, Atar İlkay

Drewno : prace naukowe, doniesienia, komunikaty

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2023

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Vol. 66, nr 212

Art. no. 177638

EN

Wood plastic composites are among the most popular engineering materials, used as deck materials as well as in construction. To improve the properties of wood plastic composites, they are reinforced with various materials. This study investigates the synergic effect of glass fiber and carbon fiber reinforcement on wood plastic composites regarding their physical, mechanical, and fire resistance performance. The reinforcement materials significantly limited the water absorption due to their hydrophobic nature. The reinforcement fibers acted as a barrier against water and limited the uptake although the water absorption and thickness swelling values increased with exposure time. Moreover, the high strength of the reinforcement fibers improved the modulus of elasticity up to 122% and 41% for the flexural strength. Additionally, the long glass fibers significantly contributed to improving the tensile strength, which indicates that fiber length is essential. The scanning electron microscope micrographs revealed that the carbon fibers had a rougher surface than the glass fibers, proving their higher resistance to stress. The observed gaps were also evidence of poor adhesion between the matrix and the fibers. On the other hand, the carbon fibers and long glass fibers positively affected the load transfer in the matrix. Unfortunately, the fiber reinforcement has only a slight effect on the fire resistance performance. Furthermore, the improvement in the limit oxygen index test values was limited. However, the reinforcement fibers exhibit a barrier effect, inhibiting dropping, which is crucial for structural integrity.

4

The use of recycled carbon fibers (rCF) in production of polymer concrete to improve mechanical properties

Smoleń Jakub

Composites Theory and Practice

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2023

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R. 23, nr 3

167--172

EN

The recycling processes for CFRP waste are difficult due to their complex, and multi-material composition. Consequently, there is a need for new solutions to address this issue. The focus of CFRP composite recycling processes is primarily on recovering costly carbon fibers, which are characterized by exceptional mechanical properties. Pyrolysis has been identified as an effective method for the recovery of carbon fibers without significant damage. In this study, recovered carbon fibers (rCF) were used to produce polymer concrete. The fabricated polymer concretes contained carbon fibers of varying lengths (10, 20, and 30 mm) and volume fractions of 1 and 3%. The results showed that the addition of 3% post-pyrolytic carbon fibers resulted in significant improvement in the mechanical properties of the polymer concrete. Specifically, the flexural strength increased by more than 100% compared to the polymer concrete without carbon fibers, while the compressive strength improved by more than 60%. Overall, the study demonstrates that incorporating post-pyrolytic carbon fibers in the production of polymer concretes offers a promising solution to the challenge of CFRP waste. The use of these fibers not only helps in the recovery of valuable resources but also results in significant improvement in the mechanical strength of the final product.

5

Effect of pressing pressure on microstructure and selected strength properties of AlSi-CF composite castings

Zyska Andrzej

Composites Theory and Practice

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2023

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R. 23, nr 4

197--201

EN

The results of the study of the microstructure and selected strength properties (Rm, E) of an aluminum composite reinforced with chopped carbon fibers are presented. Composite castings were produced by the combined method of mechanical mixing and direct squeeze casting. Silumin EN 44300 and carbon fibers with a diameter of 6-7 μm and a length of 5-6 mm with a metallic coating - Ni (Tenax) and without a coating (Fortafil) were selected for the investigations. Experiments were carried out for 4 pressure values in the range of 20-80 MPa and their impact on the structural homogeneity of the composites as well as the strength and elasticity of the castings was assessed. The beneficial effect of the metallic coating manifests itself directly in the properties of the composites. The tensile strength of the composites reinforced with Tenax fibers is approx. 250 MPa and is 10% higher than the Rm of the reference alloy of the matrix. This level of strength is achieved by applying a pressing pressure of 60 MPa. The lack of a cohesive connection of the fibers with the matrix and a significant number of internal defects in the structure of the composite reinforced with Fortafil fiber cause a reduction in its strength both in relation to the composite with Tenax fibers and the reference alloy. As part of the strength tests, it was shown that chopped carbon fibers cause a significant increase in the elastic properties (E) of composites with an AlSi matrix, while the effect of the preparation of the surface of the reinforcing phase as well as the pressing pressure on this property are insignificant.

6

PAN-Based Carbon Fibers Deposition on NiTi Surface

Goryczka Tomasz, Szaraniec Barbara, Stodolak-Zych Ewa, Kluska Stanisława

Archives of Metallurgy and Materials

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2023

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Vol. 68, iss. 3

1109--1114

EN

The main objective of the work was to create a layer of carbon nanofibre on the surface of the NiTi shape memory alloy. The coating process was carried out in three stages. First, polyacrylonitrile was deposited by electrospinning. Then it was stabilized at temperatures up to 250°C. The last stage was the carbonization performed below 1000°C. The microstructure of the obtained coatings was observed using a scanning electron microscope. The X-ray diffraction techniques were applied to analyze the coating structure. After the polyacrylonitrile deposition, the fibers had an average diameter of about 280 nm, and the final fibers were almost twice as tiny. The applied steps also changed the phase and crystalline state of the fibers, finally leading to the formation of amorphous-nanocrystalline graphite.

7

Manufacturing of Composite Castings by the Method of Fused Models Reinforced with Carbon Fibers Based on the Aluminum Matrix

Szymański Paweł

Archives of Foundry Engineering

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2023

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Vol. 23, iss. 3

118--123

EN

The paper presents an attempt to produce aluminum matrix composites reinforced with short carbon fibers by precision casting in a chamber with a pressure lower than atmospheric pressure. The composite casting process was preceded by tests related to the preparation of the reinforcement. This is related to the specificity of the precision casting process, in which the mold for shaping the castings is fired at a temperature of 720°C before pouring. Before the mold burns, the reinforcement must be inside, while the carbon fiber decomposes in the atmosphere at 396°C. In the experiment, the reinforcement in the form was secured with flake graphite and quartz sand. The performed firing procedure turned out to be effective. The obtained composite castings were evaluated in terms of the degree of alloy saturation and the displacement of carbon fibers. As a result of the conducted tests, it was found that as a result of unfavorable arrangement of fibers in the CF preform, the flow of metal may be blocked and porosity may appear in the casting.

8

Abrasive wear resistance of matrix composites carbon fiber reinforced polymers

Olejniczak Klaudia, Napiórkowski Jerzy

Technical Sciences / University of Warmia and Mazury in Olsztyn

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2022

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nr 25(1)

139--147

EN

The paper presents the results of the abrasive wear resistance test of composites based on polymers reinforced with carbon fibers. Two types of fiber composites obtained from a yacht manufacturer were used for the tests. The tests were carried out using the ball-cratering method without abrasive suspension. On the basis of the specific wear rate Kc, better tribological properties of the polyester matrix reinforced with glass fabric were observed compared to the polyester matrix reinforced with a glass emulsion mat. The composite material reinforced with glass cloth was characterized by smaller crater diameters, which may cause plastic deformation due to the low hardness of the material.

9

Antibacterial properties of carbon fibers modified with titanium sol

Wołowczyk Patrycja, Długoń Elżbieta, Syguła-Cholewińska Justyna, Bezkosty Patryk, Stodolak-Zych Ewa, Błażewicz Marta, Sitarz Maciej

Engineering of Biomaterials

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2021

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Vol. 24, no. 163

119

10

Impact strength of squeeze casting AlSi13Cu2–CF composite

Zyska A., Konopka Z., Łągiewka M.

Archives of Foundry Engineering

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2020

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Vol. 20, iss. 2

49--52

EN

The paper presents the results of research on microstructure and impact strength of AlSi13Cu2 matrix composite reinforced by Ni-coating carbon fibers (CF) with a volume fraction of 5%, 10% and 15%. The composite suspensions were prepared using by stirring method and subsequently squeeze casted under different pressures of 25, 50, 75 and 100 MPa. As part of the study, fiber distribution in aluminum matrix was evaluated and variation in impact strength of composite as a function of the carbon fibers volume fraction and pressure applied were determined. It has been found that the presence of Ni coating on carbon fibers clearly improves their wettability by liquid aluminum alloy and in combination with the stirring parameters applied, composite material with relatively homogeneous structure can be produced. Charpy's test showed that the impact strength of composite reaches the highest value by carrying out the squeeze casting process at 75 MPa. In the next stage of research, it was found that the impact strength of composites increases with the increase of carbon fibers volume fraction and for 15% of fibers is close to 8 J/cm2. Observations of fracture surfaces have revealed that crack growth in the composites propagates with a quasi-cleavage mechanism. During the creation of the fracture, all fibers arranged perpendicular to its surface were sheared. At the same time, the metal matrix around the fibers deformed plastically creating characteristic ductile breaks. The fracture surface formation through the fibers indicates a cohesive and strong connection of the reinforcement with the matrix. In addition to the phenomena mentioned, debonding the fiber-matrix interfaces and the formation of voids between components were observed on the fracture surface.

11

Carbon fiber polymer composites

Markovičová Lenka, Zatkalíková Viera, Hanusová Patrícia

Quality Production Improvement - QPI

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2019

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Vol. 1, Iss. 1

276--280

EN

Carbon fiber reinforced composite materials offer greater rigidity and strength than any other composites, but are much more expensive than e.g. glass fiber reinforced composite materials. Continuous fibers in polyester give the best properties. The fibers carry mechanical loads, the matrix transfers the loads to the fibers, is ductile and tough, protect the fibers from handling and environmental damage. The working temperature and the processing conditions of the composite depend on the matrix material. Polyesters are the most commonly used matrices because they offer good properties at relatively low cost. The strength of the composite increases along with the fiber-matrix ratio and the fiber orientation parallel to the load direction. The longer the fibers, the more effective the load transfer is. Increasing the thickness of the laminate leads to a reduction in the strength of the composite and the modulus of strength, since the likelihood of the presence of defects increases. The aim of this research is to analyze the change in the mechanical properties of the polymer composite. The polymer composite consists of carbon fibers and epoxy resin. The change in compressive strength in the longitudinal and transverse directions of the fiber orientation was evaluated. At the same time, the influence of the wet environment on the change of mechanical properties of the composite was evaluated.

12

Badania porównawcze przyczepności powłok lakierniczych stosowanych na powierzchni kompozytów polimerowych wzmacnianych włóknami węglowymi

Pieniak Daniel, Wit-Rusiecki Albin M, Krzyżak Aneta, Gil Leszek, Krzysiak Zbigniew

Przemysł Chemiczny

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2019

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T. 98, nr 10

1619--1622

PL

Powierzchnię próbek kompozytów wykonanych z impregnowanego włókna węglowego oczyszczono trzema środkami czyszczącymi (aceton, Priomat i Mould Cleaner), a następnie naniesiono na nie dwie warstwy lakieru poliuretanowego i suszono w 20°C. Ocenę właściwości mechanicznych powłok przeprowadzono, stosując test zarysowania diamentowym wgłębnikiem Rockwella. Badanie otrzymanych zarysowań przeprowadzono za pomocą mikroskopu optycznego i przez pomiar emisji akustycznej. Zastosowane 3 sposoby przygotowania powierzchni podłoża pozwoliły na uzyskanie podobnej odporności mechanicznej i adhezji powłki. Nieco lepsze wyniki uzyskano dla specjalistycznych środków czyszczących Priomat i Mould Cleaner niż dla acetonu.

EN

Me₂CO, a polyvinylbutyrate-based cleaner (Priomat) and a com. mold cleaner were used for cleaning the impregnated C fiber-reinforced composites, covered then with 2 layers of polyurethane varnish and dried at 20°C. The mech. properties of the coatings were assessed by a scratch test using a Rockwell diamond indenter. The obtained scratches were examd. by using an optical microscope and by measuring the acoustic emission. Slightly better results were obtained for the Priomat cleaner and mold cleaner than for Me₂CO.

13

Mechanical strength evaluation of poly(methyl methacrylate) reinforced with long glass, carbon and aramid fibers

Bienias Bartosz, Michalski Wojciech, Wagner Leopold

Polimery

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2019

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T. 64, nr 6

417--421

EN

The purpose of the study was the comparison of poly(methyl methacrylate) reinforced with different types of long fibers: glass, carbon, aramid, glass-aramid hybrid and carbon-aramid hybrid fibers. The test material included 48 samples in the form of a cuboid. The strength tests were performed using the Zwick 1435 machine. The highest strength increase in relation to control samples was obtained with the use of aramid fibers and the lowest with the use of glass fibers.

PL

Zbadano wytrzymałość na zginanie tworzywa akrylowego wzmocnionego długimi włóknami: szklanymi, węglowymi i aramidowymi oraz hybrydami szklano-aramidowymi i węglowo-aramidowymi. Badaniu wytrzymałościowemu w maszynie Zwick 1435 poddano 48 próbek w kształcie prostopadłościanu. Najwyraźniejszą poprawę wytrzymałości, w porównaniu z wytrzymałością próbki kontrolnej, uzyskano w wypadku zastosowania włókien aramidowych, a najmniej wyraźną w wypadku włókien szklanych.

14

Load-bearing capacity of solid timber beams with small cross section height strengthened with composite sheets

Bakalarz M., Kossakowski P.

Structure and Environment

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2018

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Vol. 10, no. 4

301--308

EN

The paper presents the results of experimental tests focused on strengthening a solid pine beams with lightweight plastics. Glass fiber reinforced sheets S&P G-Sheet E 90/10 B and carbon fiber reinforced sheets S&P C-Sheet 240 applied to the soffit of the element were used as a reinforcement. The four point bending strength test were carried out on the laboratory scale elements. Test results indicated a significant increase in ductile behavior as well as increase in load bearing capacity of beams.

PL

W pracy przedstawione zostały wyniki próby wzmocnienia litych belek sosnowych, wykorzystując lekkie tworzywa sztuczne. Zbrojenie stanowiły maty zbrojonej włóknem szklanym S&P G-Sheet E 90/10 B oraz maty z włóknem węglowym S&P C-Sheet 240 przyklejone do podbitki elementów. Próby te przeprowadzone zostały na elementach w skali laboratoryjnej poddanych czteropunktowemu zginaniu. Wyniki badań wskazały na istotny wzrost ciągliwości elementów oraz przyrost wytrzymałości na zginanie.

15

Improvement of the interfacial adhesion between fiber and matrix

Abdelhak B., Noureddine M., Hacen M.

Mechanics and Mechanical Engineering

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2018

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Vol. 22, nr 4

885--893

EN

In this work, the influence of carbon fiber surface treatment on mechanical properties of unsaturated polyester was investigated. Two approaches have been used in the surface treatment; the first is the desizing of the carbon fiber by the release of the epoxy layer. The second is with the release of epoxy layer and etching the fibers. It was concluded that both methods give good results on adhesion between the matrix and the fibers. It is found that the treatment of carbon fibers is effcient and greatly improves the CFRP handress. The tensile strength of composite materials increases by 30% for etched carbon fibers compared to untreated carbon fibers.SEM images confirm the results obtained.

16

Wybrane zagadnienia badań nad materiałami węglowymi

Doliński A.

Inżynieria Powierzchni

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2018

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nr 1

61--74

PL

Przedstawiono wybrane kierunki badań nad wytwarzaniem materiałów węglowych, koncentrując się na dwóch perspektywicznych technologiach: wytwarzaniu węgla heksagonalnego z fazy gazowej i karbonizacji/grafityzacji materiałów organicznych. Zaprezentowano obecne i przewidywane zastosowania materiałów węglowych, a także mechanizm karbonizacji/grafityzacji wielkocząsteczkowych materiałów organicznych. Podkreślono znaczenie odpadów poużytkowych jako surowca do otrzymywania materiałów węglowych do różnorodnych zastosowań.

EN

Selected paths of research on the manufacturing of carbon materials have been presented, focusing on two prospective technologies: the production of hexagonal carbon from the gaseous phase and the carbonization/graphitization of organic materials. Present and prospective applications of carbon materials and a mechanism of carbonization/graphitization of high-molecular organic materials have been presented. The importance of post-consumer waste as a raw material for obtaining carbon materials for various applications has been emphasized.

17

Kompozyty hybrydowe na osnowie polilaktydu z włóknami węglowymi i bazaltowymi

Kuciel S., Kornobis M.

Przetwórstwo Tworzyw

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2017

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T. 23, Nr 4 (178)

344--350

PL

Kompozyty hybrydowe na osnowie biodegradowalnego polilaktydu wytworzono metodą wtryskiwania z włóknami węglowymi i bazaltowymi o równowagowym udziale 7,5% i 12,5% w Zakładach Azotowych w Tarnowie. Wykonano przegląd dostępnej literatury oraz przeprowadzono szereg badań wytrzymałościowych zgodnych z Polskimi Normami. Badania te obejmowały statyczną próbę rozciągania i zginania oraz oznaczanie udarności wg Charpy’ego. Wykonano je w zmiennych temperaturach (-24, 20 i 60°C) oraz po próbie degradacji hydrolitycznej prowadzonej przez 21 dni. Za pomocą skaningowego mikroskopu elektronowego wykonano zdjęcia mikrostruktury na przełomach próbek rozciąganych. Właściwości hybrydowych kompozycji z włóknami węglowymi i bazaltowymi na osnowie polilaktydu są znacznie lepsze niż porównywalnych kompozycji z włóknem szklanym, wzrasta wytrzymałość, sztywność oraz udarność.

EN

Hybrid composites on biodegradable polylactide matrix with carbon and basalt fibers in equilibrium participation 7,5% and 12,5% were produced by molding injection in Zakłady Azotowe in Tarnow. To investigate the properties of this composition has been review of the literature and conducted series research on the strength samples according to Polish Standards. These research included: tensile test, bend test and Charpy impact test. They were done in variable temperatures (-24, 20 and 60 Celsius degree) and after hydrolytic biodegradation of materials, which lasted 21 days. We were taken photos to check fracture samples after tensile test using scanning electron microscope. The properties of hybrid composites with carbon and basalt fibers on the polylactide base are much better than comparable composites with glass fibers, increasing durability, stiffness and impact strength.

18

Pro-adhesive sol-gel coatings for fibers in epoxy resin composite materials

Szczurek A., Barcikowski M., Krzak J.

Composites Theory and Practice

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2017

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R. 17, nr 4

211--215

EN

Inadequate adhesive strength of the reinforcing fibers to the matrix in composite materials causes their delamination, which reduces the bearing capacity and durability of the defected product, and in the case of pressure vessels or pipelines, may cause their depressurization. One of possible methods to improve the adhesive strength is to coat the reinforcing fibers by the sol-gel method with organosilica coatings. Silane coatings serve two purposes: 1) the film binds chemically to the surface of the glass fiber, 2) wetting is improved by an increased chemical affinity of the resin to the fiber. Carbon and aramid fibers are usually not coated in this manner, resulting in inferior adhesive properties. In this study, organosilica materials were obtained by the sol-gel method using various silica precursors: methyltrimethoxysilane (MtMOS), ethyltriethoxysilane (EtEOS) and tetramethoxysilane (TMOS). The materials were deposited on glass fiber and hybrid carbon/aramid fiber textiles, resulting in a change in the surface properties. The chemical structures were characterized by Raman spectroscopy, indicating the presence of groups characteristic for silica, as well as the presence of functional organic groups connected by silicon-carbon bonds. The surfaces of the coated fibers were observed by scanning electron microscopy (SEM), indicating undesirable fiber bonding by the coatings obtained using the MtMOS and TMOS precursors, while no such bonding was observed for the coating obtained using the EtEOS precursor. The wettability of the glass fibers by epoxy resin was measured using the electro-optical method, revealing that the coatings made of the MtMOS and TMOS mixture improved the wettability of the fibers with epoxy resin, facilitating adhesion.

PL

Niedostateczna wytrzymałość adhezyjna połączenia włókien wzmacniających z matrycą (osnową) materiału kompozytowego prowadzi do delaminacji, powodujących redukcję zdolności do przenoszenia obciążeń oraz trwałości wyrobu, a w przypadku zbiorników ciśnieniowych i rurociągów może spowodować ich rozszczelnienie. Jedną z możliwych metod poprawy wytrzymałości adhezyjnej jest pokrywanie włókien wzmacniających metodą zol-żel powłokami organokrzemionkowymi. Warstwa silanowa wiąże się chemicznie (wiązaniami kowalencyjnymi Si-O) z powierzchnią włókien szklanych. Zwilżanie ulega poprawie dzięki większemu powinowactwu chemicznemu żywicy do włókien pokrytych niż niepokrytych. Lepsze zwilżanie poprawia powiązanie adhezyjne pomiędzy włóknami a matrycą (żywicą) ze względu na większą powierzchnię kontaktu pomiędzy żywicą a włóknami. Włókna węglowe i aramidowe zwykle nie są w ten sposób pokrywane, co skutkuje gorszymi właściwościami adhezyjnymi. W pracy materiały organokrzemionkowe zostały uzyskane metodą zol-żel z użyciem różnych prekursorów krzemionkowych: metylotrimetoksysilanu (MtMOS), etylotrietoksysilanu (EtEOS) oraz tetrametoksysilanu (TMOS). Materiały te zostały naniesione na tkaninę z włókien szklanych oraz hybrydową tkaninę węglowo/aramidową, powodując zmianę ich właściwości powierzchniowych. Struktury chemiczne zbadano z użyciem spektroskopii Ramana, wykazując obecność ugrupowań chemicznych charakterystycznych dla krzemionki, jak również obecność organicznych grup funkcyjnych połączonych wiązaniami krzem-węgiel. Powierzchnie pokrytych włókien obserwowano pod skaningowym mikroskopem elektronowym (SEM), wskazując niepożądane zlepienie włókien przez pokrycia z prekursorów MtMOS i TMOS, przy braku takiego zlepienia przez pokrycia z prekursora EtEOS. Zwilżalność włókien szklanych przez żywicę epoksydową zbadano metodą elektrooptyczną, wykazując, że pokrycia z MtMOS i TMOS poprawiają zwilżalność, promując tym samym adhezję.

19

Badania właściwości tribologicznych resorbowalnych biomateriałów na bazie polilaktydu

Karalus W., Szaraniec B., Gryń K., Chłopek J., Dąbrowski J. R., Jałbrzykowski M., Szymaniuk E.

Engineering of Biomaterials

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2015

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Vol. 18, no. 132

24--30

PL

Celem pracy było przeprowadzenie badań tribologicznych i ocena zużycia biokompozytów polimerowych. Do badań przygotowano trzy rodzaje kompozytów z polilaktydu modyfikowanego dodatkami w postaci: włókien węglowych, fosforanu trójwapnia oraz hydroksyapatytu. Ich zachowanie w warunkach tarciowych porównywano z próbkami referencyjnymi (PLA). Badania tribologiczne realizowano w warunkach tarcia suchego oraz w obecności smaru – soli fizjologicznej (roztwór wodny 0,9% NaCl). Na podstawie badań stwierdzono, że wprowadzenie modyfikatorów ceramicznych do osnowy polilaktydowej poprawiło charakterystyki tribologiczne, zaś dodatek włókien węglowych wpłynął najkorzystniej na obniżenie współczynnika tarcia (μ). Stwierdzono istotny wpływ środka smarnego. O ile w obecności smaru wartości μ dla wszystkich badanych materiałów obniżyły się, to zużycie - wyznaczone na podstawie zmian masy - zmniejszyło się tylko dla czystego polilaktydu oraz polilaktydu modyfikowanego włóknem węglowym. W przypadku kompozytów z fosforanem trójwapniowym i hydroksyapatytem zarejestrowano intensyfikację zużycia. Uzupełnieniem przeprowadzonych badań były obserwacje powierzchni testowanych próbek przy pomocy elektronowego mikroskopu skaningowego (SEM). Niezależnie od warunków (ze smarem czy też bez) najmniejszą odpornością na zużycie tarciowe cechował się czysty polilaktyd. Kompozyty z dodatkami ceramicznymi wykazywały wyraźne ślady zużycia, zaś obserwacje powierzchni kompozytów wzmacnianych włóknami węglowymi ujawniły, że zewnętrzne warstwy poddawane oddziaływaniu tarcia narażone są na fragmentacje włókien węglowych. Zjawisko to może mieć niekorzystny wpływ na możliwość aplikacji takich materiałów w warunkach pracy, w których są narażone na ścieranie.

EN

The objective of this study was the observation and evaluation of tribological characteristics and behavior of biocomposites with polymer matrix under different friction conditions. Three types of polylactide composites were considered: with addition of carbon fibers (CF), tricalcium phosphate (TCP) and hydroxyapatite (HAP). As a reference pure polylactide (PLA) samples were prepared. Tribological tests were conducted under dry friction conditions and in the presence of a lubricant – physiological saline (0.9% NaCl aqueous solution). The results clearly show that introduction of ceramic modifiers to the polylactide matrix enhanced tribological resistance of the composite and carbon fibers addition reduced the value of friction coefficient (μ). It was observed that when the lubricant was present lower values of μ were recorded for all composites but when the wear process was analyzed it was revealed that the loss of mass was reduced only for pure PLA and PLA modified with carbon fibers. For ceramic modified composites the wear processes were more intense. Scanning electron microscopy was used for surface observations of tested samples. Regardless of friction conditions (with or without lubricant) pure polylactide samples, as the softest, wear the most. When surface of composites with ceramic additives were analyzed the biggest grooves and hollows ware observed. Samples with CF exposed to friction conditions reveal inclination to fibers fragmentation, thus application of such composites in kinematic joints in biomedical devices is limited.

20

Applying stir casting method for Mg alloy-short carbon fiber composite processing

Olszówka-Myalska A., Myalski J.

Composites Theory and Practice

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2014

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R. 14, nr 2

81--85

EN

The effects of applying the stir casting method to fabricate composites with an Mg-Zn-Zr-RE magnesium alloy matrix reinforced with short carbon fibers are presented in the article. The experimental procedure carried out in industrial conditions was described. Carbon material in the form of short staple fiber granules obtained from chopped/cut carbon roving was used. The procedure of suspension fabrication and casting in ceramic and steel moulds was described. The possibility of obtaining casts of different size and shape which can be a semi-product for die casting technology has been shown. Additionally, the microstructure and mechanical properties of the obtained material were characterized.

PL

W pracy przedstawiono efekty zastosowania metody mechanicznego mieszania komponentów i odlewania suspensji (stir casting) do otrzymywania kompozytów z osnową ze stopu magnezu Mg-Zn-Zr-RE umacnianych włóknami węglowymi krótkimi. Scharakteryzowano procedury procesu technologicznego prowadzonego w warunkach przemysłowych. Użyto materiału węglowego w postaci granul włókien krótkich ciętych otrzymanych z pociętego rovingu węglowego. Scharakteryzowano procedurę przygotowania suspensji i przebieg procesu jej odlewania do form ceramicznych i stalowych. Wykazano możliwość otrzymania wlewków kompozytowych o różnym kształcie i wielkości przeznaczonych do przetopu wtórnego i odlewania ciśnieniowego. Scharakteryzowano mikrostrukturę otrzymanego materiału i określono jego właściwości mechaniczne.