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1

Fabrication, microstructure, and machinability of aluminum metal-matrix composites

Kathiravan S., Thanigaivelan R., Suresh P.

Materials Science Poland

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2022

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Vol. 40, No. 3

112--124

EN

Today, researchers across the world focus on sustainable products, and, accordingly, it is now imperative to develop sustainable MMCs. In line with this, ongoing experimental work aims to fabricate aluminum 6061 MMC with ground granulated blast furnace slag (GGBS) and study the micro-structural and machinability characteristics. A liquid state stir casting setup is used to melt aluminum 6061 alloy and reinforced with 2.5 wt.%, 5.0 wt.%, and 7.5 wt.% of GGBS. X-ray diffraction (XRD) studies were used to identify the chemical elements that were present in the fabricated samples. In order to observe the formation of any secondary elements, energy-dispersive X-ray spectroscopy and scanning electron microscopy (SEM) were utilized on the cast composites. Through the milling process, the influence of the GGBS reinforcement composition on the surface roughness (SR) and material removal rate (MRR) of aluminum 6061 MMC was examined, considering the parameters of spindle speed, feed rate, depth of cut, and reinforcement composition percentage. The L9 orthogonal array (OA) was used to investigate the results of the experiments, and the Taguchi technique was used to optimize the process. The best MRR value was produced by the feed rate (B3) of 260 mm3/min and the depth of cut (C3) of 0.75 mm. The study ascertained that the lower SR value is attained corresponding to a spindle speed of 1,250 rpm, a feed rate of 220 mm3/min, a depth of cut of 0.25 mm, and a reinforcement composition percentage of Al 6061 with 5% GGBS.

2

Tailoring the mechanical properties of hypereutectic in situ Al–Mg2Si composites via hybrid TiB2 reinforcement and hot extrusion

Moazami Mohammad Rasool, Razaghian Ahmad, Mirzadeh Hamed, Emamy Massoud

Archives of Civil and Mechanical Engineering

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2022

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Vol. 22, no. 2

art. no. e87, 1--9

EN

Microstructure and mechanical properties of Al-15Mg 2 Si-xTiB 2 hybrid composites in the as-cast and wrought conditions were studied. TiB 2 addition led to a significant refinement and modification of primary Mg2Si particles (up to 3 wt% TiB 2 addition) via the heterogeneous nucleation mechanism, which improved the as-cast tensile properties. Further additions led to the appearance of coarse needle-shaped Al 3Ti particles with the consequent deterioration of tensile properties. Hot deformation by extrusion process and elevated-temperature exposure resulted in the fragmentation, dispersion, and spheroidization of pseudo-eutectic Mg 2 Si constituents, which led to a significant enhancement of tensile properties. The ultimate tensile strength of the extruded Al-15Mg 2 Si-3TiB 2 composite was 285 MPa with the total elongation of ~ 8%, which revealed a good strength-ductility balance. The corresponding value for the as-cast Al-15Mg 2 Si composite was only 198 MPa%. Accordingly, this study revealed that the presence of optimum amount of TiB 2 combined with high-temperature thermo-mechanical processing could remarkably improve the mechanical properties of the hypereutectic Al-Mg-Si composites in terms of strength-ductility balance, quality index, and tensile toughness.

3

A multiscale experimental analysis of mechanical properties and deformation behavior of sintered copper-silicon carbide composites enhanced by high-pressure torsion

Nosewicz Szymon, Bazarnik Piotr, Clozel Melanie, Kurpaska Łukasz, Jenczyk Piotr, Jarząbek Dariusz, Chmielewski Marcin, Romelczyk-Baishya Barbara, Lewandowska Malgorzata, Pakieła Zbigniew, Huang Yi, Langdon Terence G.

Archives of Civil and Mechanical Engineering

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2021

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Vol. 21, no. 3

776--794

EN

Experiments were conducted to investigate, within the framework of a multiscale approach, the mechanical enhancement, deformation and damage behavior of copper–silicon carbide composites (Cu–SiC) fabricated by spark plasma sintering (SPS) and the combination of SPS with high-pressure torsion (HPT). The mechanical properties of the metal–matrix composites were determined at three different length scales corresponding to the macroscopic, micro- and nanoscale. Small punch testing was employed to evaluate the strength of composites at the macroscopic scale. Detailed analysis of microstructure evolution related to SPS and HPT, sample deformation and failure of fractured specimens was conducted using scanning and transmission electron microscopy. A microstructural study revealed changes in the damage behavior for samples processed by HPT and an explanation for this behavior was provided by mechanical testing performed at the micro- and nanoscale. The strength of copper samples and the metal–ceramic interface was determined by microtensile testing and the hardness of each composite component, corresponding to the metal matrix, metal–ceramic interface, and ceramic reinforcement, was measured using nano-indentation. The results confirm the advantageous effect of large plastic deformation on the mechanical properties of Cu–SiC composites and demonstrate the impact on these separate components on the deformation and damage type.

4

Corrosion and thermal shock resistance of metal (Cu, Al) matrix composites reinforced by SiC particles

Strojny-Nędza A., Egizabal P., Pietrzak K., Zieliński R., Kaszyca K., Piątkowska A., Chmielewski M.

Bulletin of the Polish Academy of Sciences. Technical Sciences

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2020

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Vol. 68, nr 5

1227--1236

EN

This paper presents the results of studies concerning the production and characterization of Al-SiC/W and Cu-SiC/W composite materials with a 30% volume fraction of reinforcing phase particles as well as the influence of corrosion and thermal shocks on the properties of selected metal matrix composites. Spark plasma sintering method (SPS) was applied for the purpose of producing these materials. In order to avoid the decomposition of SiC surface, SiC powder was coated with a thin tungsten layer using plasma vapour deposition (PVD) method. The obtained results were analysed by the effect of the corrosion and thermal shocks on materials density, hardness, bending strength, tribological and thermal properties. Qualitative X-ray analysis and observation of microstructure of sample surfaces after corrosion tests and thermal shocks were also conducted. The use of PVD technique allows us to obtain an evenly distributed layer of titanium with a constant thickness of 1.5 µm. It was found that adverse environmental conditions and increased temperature result in a change in the material behaviour in wear tests.

5

Study on modalities and microdefects of Al-Cu bimetallic tube by underwater explosive cladding

Yu Yong, Xu Peibao, Li Kai, Zhao Jun, Dai Yuntong, Ma Honghao, Yang Ming

Archives of Civil and Mechanical Engineering

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2019

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Vol. 19, no. 4

1390--1398

EN

In this study, a screwed copper tube was cladded an aluminum tube by a new explosive cladding method. To study the modalities of the bonding interface, a light microscope was used to observe the bonding interface. To expose the weak position of the interface, a three-point bending test was conducted under extreme condition. Then the BSE (Backscattering Electron) images of the bent interfaces were obtained. Meanwhile, the EDS (Energy Disper-sive Spectrometry) analyses of the melted zone were performed. The results of the light microscopic observations show that there are four bonding modalities on the interface. They can be summarized to two bonding modalities: direct bonding and bonding with the melted zone. There are no macro cracks on the interface of the bent specimens, which represents a reliable joining generally. The elastic modulus of Al-Cu bimetallic tube along the axial direction is 85.2Gpa. The BSE images, the EDS analyses and the microhardness tests show the direct bonding with some characteristics of the micro wavy interface is a pretty nice bonding pattern. The melted zone composed of CuAl2 is a weak bonding pattern, which may affect the mechanical property of the joint.

6

The Hardening in Alloys and Composites and Its Examination with a Diffraction and Self-Consistent Model

Gadalińska E., Baczmański A., Wroński S., Wróbel M., Scheffzük C.

Fatigue of Aircraft Structures

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2018

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Iss. 10

31--46

EN

The paper presents the results of diffraction stress measurement in Al/SiC composite and in 2124T6 aluminum alloy during the in situ tensile test. The main aim of the work is to observe the stress values for different stages of tensile test for the composite after applying two types of thermal treatment and for the alloy used as a matrix in this composite, to identify the type of hardening process. The experimental results were compared against the calculations results obtained from the self-consistent model developed by Baczmański [1] - [3] to gain the information about the micromechanical properties (critical resolved shear stress τcr and hardening parameter H) of the examined materials. This comparison allowed researchers to determine the role of reinforcement in the composite as well as the impact of the heat treatment on the hardening of the material.

7

Tribological properties of sintered of bronze-based composites reinforced with Al-based hard particulares

Dyachkova L., Feldshtein E., Letsko A., Kiełek P., Kiełek T.

Composites Theory and Practice

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2017

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R. 17, nr 2

84--89

EN

This paper describes the changes in the tribotechnical properties of CuSn10 sintered bronze and MMCs based on this bronze reinforced with ultrafine composite Al-based powders. It was observed that the presence of hard particulates in the MMCs leads to a decrease in the friction coefficient and, particularly, wear rate. The presence of Al-based particulates in the MMC reduces the wear rate considerably. It decreases in the direction of FeAl → NiAl → Ti-Al-Cr particulates and for the best MMC composition the gain is about 20 times. In the MMC wear process, micro-craters are formed on the contact surface and it is the principal reason for the decrease in the wear rate.

PL

W pracy zbadano zmiany właściwości tribotechnicznych spiekanego brązu CuSn10 oraz kompozytów metalowych na bazie tego brązy umocnionego twardymi cząstkami proszków na bazie aluminium: FeAl, NiAl oraz Ti-46Al-8Cr. Obecność w kompozycie twardych cząstek na bazie Al prowadzi do zmniejszenia współczynnika tarcia i intensywności zużycia. Temperatury w strefie styku są stabilne, maksymalne temperatury zaobserwowano w warunkach wzrastającego obciążenia. Intensywność zużycia zmniejsza się w kierunku FeAl → NiAl → Ti-Al-Cr cząstek i dla kompozytu o najlepszym składzie przewaga sięga 20 razy. Zasadniczą przyczyną zmniejszenia intensywności zużycia są mikrokratery powstające na powierzchniach styku.

8

Study on Underwater Explosive Welding of Al-Steel Coaxial Pipes

Yu Y., Ma H., Zhao K., Shen Z., Cheng Y.

Central European Journal of Energetic Materials

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2017

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Vol. 14, no. 1

251--265

EN

In order to solve the aluminum surface ablation issue of Al-Steel bimetallic pipes manufactured by the explosive welding technique, a novel explosive welding system has been designed to weld Al-Steel coaxial pipes. The stand-off distance was chosen according to an empirical formula. A special Explosive Cord with an aluminum coating was used as the explosive. Four experiments were performed using Explosive Cords 1, 2, 3 and 4, respectively. In each experiment, three reliable PVDF (Polyvinylidene Fluoride) piezoelectric film sensors were used to sample the impact pressure between the parent pipe and the flyer pipe along the detonation direction. p-t Curves were obtained at different points on the bimetallic pipe manufactured by Explosive Cord 1. In order to observe the inner surface and to judge the bonding interface, specimens were cut along the axial direction. BSE (Backscattering Electron) images of the interfaces were obtained. According to these pictures from all of the specimens cut along the axial direction, the surface ablation phenomenon has disappeared. The bimetallic pipe manufactured by the new welding system using Explosive Cord 3 has an irregular wavy interface, between micro and small wavy interface, which is one of the best bonding forms.

9

Przewodnictwo cieplne kompozytów o osnowie metalowej zbrojonych węglem

Homa M.

Prace Instytutu Odlewnictwa

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2016

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Vol. 56, no. 4

329--350

PL

Praca przedstawia krytyczną analizę obecnego stanu wiedzy na temat właściwości termofizycznych metalowych materiałów kompozytowych, w których zastosowano różne typy zbrojącej fazy węglowej: grafit, diament, włókna węglowe, nanorurki węglowe, fulleren, grafen, tlenek grafenu. Materiały te musi cechować wysokie przewodnictwo cieplne (powyżej 300 W·(m·K)-1), rozszerzalność cieplna zbliżona do materiału, z którego ciepło jest odprowadzane (4‒9 × 10-6·K-1), niskie przewodnictwo elektryczne, duża odporność na działanie erozyjne łuku elektrycznego, niska i stabilna rezystancja zestykowa. Zastosowanie różnych typów zbrojenia węglowego o strukturze typu 2D, jak nanorurki węglowe, fullereny, grafen czy tlenek grafenu otwiera nowe możliwości w zakresie kształtowania właściwości termofizycznych, w tym przewodności cieplnej. Niestety, zaawansowane metalowe kompozyty zbrojone fazą węglową o strukturze 2D są nadal rzadko stosowane ze względu na nierozwiązane dotąd problemy technologiczne łączenia matrycy metalowej z fazą węglową typu 2D, co przekłada się na niezadawalającą przewodność cieplną tych materiałów oraz skomplikowany proces produkcji i ich cenę.

EN

The paper presents a critical analysis of the current state-of-the-art thermo-physical properties of metal composite materials, in which different types of carbon reinforcing phase have been used: graphite, diamond, carbon fibres, carbon nanotubes, fullerene, graphene and graphene oxide. These materials must possess high thermal conductivity (above 300 W·(m·K)-1), thermal expansion similar to that of the material from which the heat is removed (4–9 × 10-6·K-1), low electric conductivity, high erosion resistance of the electric arc, as well as low and stable contact resistance. The application of various types of carbon reinforcement with a structure of the 2D type, such as carbon nanotubes, fullerenes, graphene or graphene oxide, opens new possibilities in the field of the formation of thermo-physical properties, including thermal conductivity. Unfortunately, advanced metal composites reinforced with a 2D type carbon phase are still rarely used, due to the unsolved technological problems connected with joining the metal matrix with the 2D type carbon phase, which results in unsatisfactory thermal conductivity of these materials as well as a complicated production process and a high price.

10

Electroless Deposition of Composite Nickel-Phosphorous Coatings with Diamond Dispersoid

Petrova M., Georgieva M., Chakarova V., Dobreva E.

Archives of Metallurgy and Materials

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2016

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Vol. 61, iss. 2A

493--498

EN

The composite Ni-P coating with diamond particles (D) deposited on the flexible substrates of pressed polyethylene terephthalate material (PET) was obtained, to be used in the development of efficient, flexible grinding and polishing tools. The optimal conditions of the hydrodynamic regime, deposition time and temperature were found. The influence of the concentration and size of the D particles (3/7 ÷ 225/300 μm) on the coating thickness and number of co-deposited particles were studied. By Scanning Electron Microscopy (SEM) images were defined the morphology of dispersion coatings and number of co-deposited particles in them, and Energy Dispersive Spectroscopy (EDS/INCA) was used to determine the elemental chemical composition of the composite coatings.

11

Nagniatanie dynamiczne kompozytów o osnowie metalowej

Bławucki S., Zaleski K.

Mechanik

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2015

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R. 88, nr 3

163--167

PL

Przedstawiono metody obróbki nagniataniem dynamicznym. Opisano nagniatanie dynamiczne stopów lekkich niezbrojonych oraz wybranych stopów lekkich zbrojonych cząstkami ceramicznymi. Zaprezentowano stan obecny i perspektywy rozwoju nagniatania dynamicznego kompozytów o osnowie metalowej.

EN

The article presents shot peening (or dynamic burnishing) process methods. Described are the shot peening operations applied to plain light metal alloys and to the light metal alloys reinforced with ceramic particles (whiskers). Also presented is the current state of the art and development prospects for application of the shot peening process on metal-matrix composites.

12

Kompozyty spiekane Cr-Al2O3 z dodatkiem renu: wytwarzanie, właściwości, modelowanie, zastosowania

Basista M., Pietrzak K., Węglewski W., Chmielewski M.

Rudy i Metale Nieżelazne

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2013

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R. 58, nr 10

556--563

PL

Celem pracy było zbadanie wpływu dodatku renu na właściwości termomechaniczne i użytkowe kompozytów Cr-Al2O3 wytwarzanych metodą spiekania pod ciśnieniem w prasie HP oraz metodą Spark Plasma Sintering (SPS). Uzyskano kompozyty o gęstości przekraczającej 98 % gęstości teoretycznej. Właściwości mechaniczne (m.in. moduł Younga, wytrzymałość na zginanie, twardość, odporność na pękanie, granica plastyczności) oraz odporność na utlenianie wytworzonych materiałów są obiecujące. Zbudowano model numeryczny do obliczeń wielkości naprężeń resztkowych obecnych w materiałach faz kompozytu po procesie spiekania oraz modułów sprężystości. Wykorzystano w tym celu obrazy rzeczywistej mikrostruktury kompozytu otrzymane z tomografii komputerowej. Uzyskano dobrą zgodność wyników modelu z wynikami pomiarów naprężeń metodą XRD. Przedstawiono ponadto porównanie wyników obliczeń numerycznych i pomiarów modułu Younga przy zastosowaniu różnych metod.

EN

Chromium matrix composites reinforced with alumina ceramic particles exhibit good resistance to high temperatures are thermal shocks. They have enhanced mechanical strength in elevated temperatures, high hardness, oxidation resistance and wear resistance. These exceptional properties make them good candidates for structural applications in automotive, aerospace and energy sectors, such as elements of combustion engines, coatings in aeroengines exhaust systems, or furnace linings. The objective of the present paper is to investigate the effect of rhenium addition on the thermomechanical and service properties of chromium-alumina composites manufactured by powder metallurgy methods. A working hypothesis was made that rhenium, owing to its excellent thermomechanical properties, would enhance the properties of the chromium matrix and, thus, improve the overall performance of the composite. The Cr/Al2O3/Re composites were processed by hot pressing (HP) and by spark plasma sintering (SPS) techniques. Different sizes of chromium powders were used, the addition of rhenium was 2 vol % and 5 vol %. The sintering process was conducted at 1400-1450 °C under pressure of 30-35 MPa in inert gas atmosphere (argon). The density of the sintered composites exceeded 98 % of the theoretical density. The mechanical properties (Young’s modulus, bending strength, hardness, plastic limit) are promising. For example, the compressive strength of the composite was twice as much as that of the sintered pure chromium. The oxidation and corrosion resistance of the composites were also examined and good results were reported. A numerical FE model was developed for the prediction of thermal residual stresses generated in the phase materials after cooling. The model uses micro-CT images of the real material microstructure as the input data. A good agreement of the simulation results and the measurements by X-ray diffraction method was achieved. Young’s modulus of the obtained materials was measured by different methods (mechanical, resonance and ultrasonic) and compared with the developed micro-CT based numerical model. The obtained Cr/Al2O3/Re composites are now being tested as demonstrators of some structural elements in automotive and energy applications.

13

Kompozyty Cu-diament o dużym przewodnictwie cieplnym wytwarzane metodą PPS

Kruszewski M., Rosiński M., Grzonka J., Ciupiński Ł., Michalski A., Kurzydłowski K. J.

Materiały Ceramiczne

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2012

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T. 64, nr 3

333-337

PL

Jednym z głównych problemów przy spiekaniu kompozytu miedź/diament, obok procesu grafityzacji w wysokich temperaturach, jest brak zwilżalności diamentu przez miedź i brak reakcji chemicznych prowadzących do tworzenia związków Cu-węgiel, które zapewniałyby dobre połączenie diamentu z osnową z miedzi. Ponadto duża różnica rozszerzalności cieplnej tych materiałów powoduje powstawanie podczas spiekania naprężeń cieplnych osłabiających granicę miedź/diament i skutkujących powstawaniem pustek zmniejszających przewodnictwo cieplne kompozytu. Granica międzyfazowa Cu-diament odgrywa kluczową rolę warunkującą przewodnictwo cieplne i właściwości mechaniczne kompozytu. Idealne połączenie powinno zapewnić zarówno dobrą adhezję, jak i minimalny opór cieplny. Przedmiotem badań autorów pracy były kompozyty na osnowie miedzi zawierające 50% obj. cząstek diamentu. Kompozyty zostały otrzymane w warunkach nietrwałości termodynamicznej diamentu z wykorzystaniem konsolidacji metodą PPS (Pulse Plasma Sintering) w temperaturze 900°C pod naciskiem 60 MPa. W pracy opisano wyniki badań składu fazowego, gęstości oraz obserwacji mikrostruktury próbek. Gęstość względna wyniosła 99,8%, a badania składu fazowego nie wykazały obecności grafitu. Obserwacje mikrostruktury wykazały równomierny rozkład cząstek diamentu w osnowie miedzi. Dobre połączenie diamentu z osnową uzyskano dzięki warstwie przejściowej z węglika chromu.

EN

One of the main challenges in fabrication of copper/diamond composites, apart from graphitization at high temperatures, is a lack of wettability of diamond by copper and the absence of chemical reactions, providing the formation of Cu-carbon compounds needed for a good joint between the diamond and the copper. Moreover, the large mismatch in the values of thermal expansion coefficients of these materials is a reason for high thermal stresses during sintering that are disadvantageous to the cohesion of the diamond/copper interface. The thermal stresses promote voids formation, which reduces the thermal conductivity of the composite. In metal-diamond composites, the quality of the interface has a crucial effect on their thermal conductivity and mechanical properties. Strong and "clean" bond of the diamond to the matrix should assure high strength and minimum thermal resistance of the interface. In the present work, an attempt has been made to fabricate the copper matrix composite with 50 vol.% of diamond by using the Pulse Plasma Sintering (PPS) technique in the conditions of thermodynamical instability of diamond. The composites have been fabricated at 900 °C under 60 MPa. The phase composition, density and microstructure studies showed a relative density of 99,8% and the absence of graphite. The microstructure examinations revealed uniform distribution of diamond particles in the copper matrix. Good bonding of the diamond to the matrix have been assured by a layer of chromium carbide at the interface.

14

Structure homogeneity as a parameter for evaluation of composite casting quality

Gawdzińska K., Wojnar L., Maliński M., Chrapoński J.

Archives of Foundry Engineering

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2010

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Vol. 10, iss. 3

187--192

EN

The structure of composite materials is be usually described as a compound of two structural components called matrix and reinforcement, respectively. A classic, commonly known example is polyester resin reinforced with glass fibres. Composite materials obtained through casting techniques are frequently characterised by irregular distribution and content of reinforcement in the casting volume as well as by different shape and size of this structural element [1–5]. It clearly results from the fundamentals of materials engineering that this type of structural diversity has a crucial effect on its broadly understood properties. Therefore, a need arises to define in a simple but precise way what we understand as homogeneity or non-homogeneity of the material, as well as for introduction of measures for this feature. The present study is limited to cast metal-matrix composite materials that, due to their manufacture technology, are particularly susceptible to the occurrence of non-homogeneity. However, the proposed solution may be also applied in characterisation of other materials. Till now, the concept of non-homogeneity has no commonly accepted definition [6-10]. Among others, it is defined as: – deviation of certain geometric features from the structure accepted conventionally as homogenous; – local structure disorder, the intensity of which is accomplished with different probability; – derivative of the diversity of geometric features of measured elements which results from their orientation (anisotropy) or position (gradient) in a tested object. In the case of composite castings when the concept of defect as deviation from the desired features is being used as a rule in describing the quality parameters of these materials, it seems to be advisable to introduce the concept of material homogeneity. Deviation from this feature, i.e. a defect, will be the non-homogeneity of, for instance, structure porosity or amount, spatial distribution, size or shape of reinforcing phase precipitations. This paper presents a proposal for complex determination of reinforcement structure homogeneity along with its practical application.

15

Próby recyklingu kompozytów z nasycanym zbrojeniem grafitowym i osnową ze stopu OT7

Nagolska D., Szweycer M.

Kompozyty

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2006

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R. 6, nr 2

55-59

PL

Przebieg recyklingu kompozytów metalowych z nasycanym zbrojeniem drogą rozdzielenia składników zależy między innymi od właściwości powierzchniowych układu: zbrojenie - ciekła osnowa - ośrodek oraz struktury zbrojenia kompozytu. W pracy przedstawiono wyniki analizy warunków wypływania ciekłego metalu osnowy z porów zbrojenia (rys. 3). Stwierdzono, iż z powodu skomplikowanej budowy porów zbrojenia kompozytowego wartości ciśnienia działającego na metal osnowy są zmienne (rys. 4). Może to doprowadzić do lokalnego zatrzymania procesu wypływania ciekłej osnowy ze zbrojenia kompozytu (rys. 5). Matematyczny opis geometrii zbrojenia jest bardzo trudny, a niekiedy nawet niemożliwy, wobec tego postanowiono eksperymentalnie zbadać przebieg wypływania osnowy metalowej z dwóch kształtek zbrojenia wykonanych z tego samego materiału, ale wyraźnie różniących się strukturą. Do badań wytypowano kompozyt o osnowie ze stopu ołowiu z antymonem OT7 zbrojony kształtkami grafitowymi w postaci spieku i prasowanych włókien (tab. 1 i rys. 6), które różni zarówno kształt, jak i wymiary porów. Kompozyty te poddano recyklingowi w dwóch ośrodkach: powietrzu i mieszance stopionych soli (tab. 2). W przypadku kompozytu zbrojonego spiekiem grafitowym poddanego recyklingowi w powietrzu uzysk był nieznaczny, niewiele przekraczający 5%, natomiast w ośrodku stopionych soli zaobserwowano uzysk rzędu 35%. Uzysk metalu z kompozytu zbrojonego włókniną grafitową w powietrzu wynosił również niewiele (ok. 9%), natomiast w ośrodku stopionych soli wyniósł ponad 90%. Uzyskane wyniki potwierdziły, iż na proces wypływania ciekłej osnowy metalowej z porów zbrojenia mają wpływ właściwości powierzchniowe. Otrzymane wyniki obliczeń oraz przeprowadzone badania wskazują jednak, iż na proces recyklingu ma duży wpływ również struktura zbrojenia. Przy identycznych właściwościach powierzchniowych układu i różnej strukturze zbrojeniach otrzymujemy bowiem znaczne różnice w uzysku metalu (rys. 7). Przeprowadzona analiza wskazuje, iż struktury zbrojenia charakteryzują kąty rozwarcia kapilary [alfa] oraz wartości średnic d1 i d2, a także stosunek tych wartości. Zaprezentowana w niniejszym artykule analiza jakościowa nie jest wystarczająca do określenia wpływu zmienności parametrów struktury na uzysk metalu. Aby możliwe było określenie zależności uzysku metalu od tych parametrów, konieczne jest przeprowadzenie analizy ilościowej, co wszakże utrudnia lub nawet uniemożliwia brak możliwości opisu matematycznego struktury. Wykonane doświadczenia dotyczące kompozytu: stop OT7 - zbrojenie grafitowe umożliwiły jednak określenie, które z badanych zbrojeń posiada lepszą strukturę z punktu widzenia recyklingu. Wynika z nich, iż parametry struktury zbrojenia w postaci włókien są znacznie korzystniejsze niż zbrojenia w postaci spieku.

EN

Recycling of metal composites with saturated reinforcement by separation of the components depends, among others, on surface properties of the reinforcement - liquid matrix - environment system, and the structure of composite reinforcement. The paper presents the results of the analysis of conditions of liquid matrix metal outflow from the reinforcement pores (Fig. 3). It was found that due to complicated structure of the composite reinforcement pores the values of the pressure acting on the matrix metal vary (Fig. 4). This might be conducive to local stoppage of the process of liquid matrix outflow from the composite reinforcement (Fig. 5). Mathematical description of the matrix geometry is very difficult or sometimes even impossible. In consequence, the course of metal matrix outflow from two reinforcement profiles made of the same material of clearly different structures were investigated experimentally. For the investigation purposes a composite of the lead - antimony alloy (OT7) was selected, reinforced with graphite profiles in the form of a sinter and pressed fibers (Table 1 and Fig. 6), of different shapes and pore sizes. The composites have been recycled in two surroundings: air and a mixture of molten salts (Table 2). In case of the graphite sinter reinforced composite recycled in air the yield was insignificant, barely exceeding 5 per cent. On the other hand, in the case of molten salts the yield of 35 per cent was achieved. The metal yield obtained from a graphite fiber reinforced composite was also small, amounting to 9 per cent, reaching 90 per cent for the case of the environment of molten was. The results so obtained confirmed that the process of liquid metal matrix outflow from the reinforcement pores is affected by the surface properties. Results of the calculation and the research indicate that the recycling process is also highly affected by the reinforcement structure. In case of identical surface properties of the system and different reinforcement structures the differences in metal yield values are significant (Fig. 7). The analysis shows that the reinforcement structure is characterized by the angels of flare of the capillaries [alpha], the diameters d1 and d2, and ratios of these values. The quantitative carried out in the present paper is insufficient for purposes of determining the effect of variability of the structure parameters on the metal yield. In order to enable determining influence of these parameters on the metal yield a qualitative analysis must be performed that may be difficult or even unfeasible because of impossibility of mathematical description of the structure. Nevertheless, the experiments related to the OT7 alloy - graphite reinforcement composite enabled answering the question which of the reinforcement types subject to the study has better structure from the recycling point of view. They show that parameters of the reinforcement structure in the form of fibers are more advantageous than for sinter reinforcement.

16

Problemy wytwarzania kompozytów z osnową metaliczną zbrojoną włóknami węglowymi

Gabrylewski M., Patejuk A.

Aparatura Badawcza i Dydaktyczna

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2004

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T. 9, nr 3

156--168

PL

Materiały kompozytowe z metalową osnową określa się mianem materiałów nowej generacji. Szczególnie dotyczy to materiałów z osnową na bazie lekkich stopów (np. aluminiowych). Wytwarzanie na szeroką skalę tych materiałów napotyka na wiele trudności technologicznych, których pokonanie decydująco rzutuje na wysoki koszt wytwarzania tych materiałów. W pracy ogólnie scharakteryzowano materiały kompozytowe z osnową metaliczną zbrojoną włóknami, ze szczególnym uwzględnieniem włókien węglowych. Wysokie własności mechaniczne włókien węglowych, w zestawieniu z ich niewielkim ciężarem właściwym oraz stosunkowo niskim kosztem wytwarzania, predestynują je do roli perspektywicznych komponentów zbrojących w materiałach kompozytowych z osnową metaliczną

EN

Metal-matrix composites has been known as new generation materials. Especially there are materials where as a matrix light alloy ex. Aluminum has been used. Manufacturing processes of such materials on large scale has been met some technological problems. To defeat such a problem is connected with high cost of manufacturing. This work presents general properties of reinforced metal-matrix composites, where carbon fiber made reinforced material particularly. High mechanical properties of carbon fiber connected with small specific weight (gravity) and competitive small cost of manufacturing, predestinate them to be the best perspective reinforced material for metal-matrix composites.