Ograniczanie wyników
Czasopisma help
Autorzy help
Lata help
Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 101

Liczba wyników na stronie
first rewind previous Strona / 6 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  metal matrix composites
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 6 next fast forward last
EN
Purpose: This paper presents an overview on some ceramic materials capable of achieving in-situ reinforcements in Al/Al-alloy metal matrix composites (MMCs) during laser processing. It also presents perspective on further exploitation of the in-situ reinforcement capabilities for high quality MMCs feedstock material development. Design/methodology/approach: The approach utilized in writing this paper encompasses the review of relevant literature on additive manufacturing (AM) of MMCs. Findings: It is widely accepted that the in-situ reinforcement approach has proven to be more advantageous than the ex-situ approach. Though there are still some challenges like the formation of detremental phases and the evaporation of low melting temperature elements, the in-situ reinforcement approach can be used to tailor design composite powder feedstock materials for the AM of MMCs. The preprocessing or tailor-designing in-situ metal matrix composite powder before laser melting into desired components holds more promises for metal additive manufacturing. Practical implications: The need for the development of MMCs powder feedstock that can be directly fabricated using suitable AM technique without prior powder processing like blending or mechanical alloying has not yet been addressed Therefore, having a pre-processed in-situ reinforced MMC feedstock powder can encourage easy fabrication of MMC and other advantages of AM technologies powder recycling. Originality/value: The idea explained in this article is relevant to materials development for AM processing of metal matrix composite. This paper has pointed out future trends for MMCs materials feedstock powder development and new ideas for further exploitation of MMCs and AM technologies. The advantages of tailor-designing composite powders other than merely mixing them has been emphasized.
EN
Current work attempts to fabricate aluminium alloy AA2219 metal matrix composite (AMC) reinforced with natural bio-based sea shell powder (SSP) which is a ceramic material, in view of improving the mechanical and tribological properties. SSP was characterized by X-Ray Diffraction (XRD) to assess its chemical constituents and particle size. Stir casting route was adopted for fabricating AMCs reinforced with 1, 2 and 3 wt.% of SSP. Energy Dispersive X-ray Spectroscopy (EDS) was used to analyse the formation of secondary elements during casting and scanning electron microscopy (SEM) was used analyze the surface morphology of the composite specimen before and after tribological tests. Hardness, Compressive strength and tribological properties were evaluated using appropriate tests and corresponding ASTM standards. Characterization methods revealed that the formation of secondary elements was very low at 3 wt.% of SSP when compared with other compositions. Hardness and compressive strength was found to be maximum for 3 wt.% of SSP while the specific wear rate and coefficient of friction values were found to be lesser for the same composite when compared with the unreinforced alloy and were on par with the AA2219 composites containing synthetic reinforcements.
EN
The paper presents the application of the casting method for the production of porous composites, called syntactic foams, of the casting alloy - solid particles type. This method was used to produce composites based on Al alloys reinforced with particles of clinoptilolite, a natural mineral from the zeolite group. Before the casting process, tests were carried out on the morphology, physicochemical properties and chemical composition of the zeolite, which was obtained from a rock called zeolite tuff, mined in a quarry in Kucin, (VSK PRO-ZEO s.r.o., Slovakia). Observations of the microstructure of the produced composites were also carried out using a scanning electron microscope. Diffractometric tests of zeolite rock as delivered for research and of the produced samples reinforced with zeolite particles were also carried out. Initial studies of the density and porosity of the produced composites were performed. The usefulness of the presented method of composite production was assessed on the basis of the conducted structural tests, with particular emphasis on the particle distribution in the alloy matrix.
EN
Boron nitride (BN) reinforced Al6061 aluminum-based composites are synthesized by conventional stir casting method followed by exposure to hot extrusion. The optical images confirmed the distribution of BN nanoparticles in the aluminum alloy matrix. The concentration of BN is varied from (0.5, 1.5, 3, 4.5, 6, 7.5, and 9 wt%) in the composites and its effect on the tensile strength was investigated. The results revealed that both extruded and heat-treated composites specimens showed enhanced toughness and tensile strength by increasing BN nanoparticle concentration. The heat-treated composite samples showed lower flexibility of up to 40%, and further, it exhibited 37% greater hardness and 32% enhancement in tensile strength over the extruded sample. The tensile properties of Al6061-BN composites were evaluated by temperature-dependent internal friction (TDIF) analysis and the results showed that the as-prepared composite's strength increased with temperature.
EN
Nowadays, the global industries producing mechanical components are moving towards the usage of composites to reduce weight at the same time without compromising with characteristics of the material being used. This new combination of material provides specific desired properties when combined with various reinforcement materials like SiC, B4C, Al2O3, MgO etc., It is widely used in various industries like aerospace, automobile and marine industries. This property specific tailorable metal matrix composite with Al7075 as the base material can be fabricated using various techniques such as stir casting, high end ball milling, ultrasonic assisted casting, powder metallurgy, squeeze casting friction stir casting etc., out of which stir casting method is preferred by many researchers as stir casting method is seen to provide better distribution of reinforcement particles throughout the metal matrix. It is evident from the research of various authors that when the base material Al7075 is reinforced with the above-mentioned ceramic, it is found that there is a decrease in density and increase in hardness, compressive strength and wear resistance. Here, both physical and mechanical behaviour of aluminium reinforced composites with the effect of the particle size changes, effects after reinforcement and other processing and fabrication methods have been discussed.
EN
Magnesium Metal Matrix Composites (Mg MMC) have been the focus of consideration by many researchers for the past few years. Many applications of Mg MMCs were evolved in less span of time in the automotive and aerospace sector to capture the benefit of high strength to weight ratio along with improved corrosion resistance. However, the performance of these materials in critical conditions is significantly influenced by several factors including the fabrication methods used for processing the composites. Most of the papers addressed all the manufacturing strategies of Mg MMC but no paper was recognized as a dedicated source for magnesium composites prepared through STIR casting process. Since STIR casting is the least expensive and most common process in the preparation of composites, this paper reviews particulate based Mg MMCs fabricated with STIR casting technology. AZ91 series alloys are considered as the matrix material while the effect of different particle reinforcements, sizes, weight fractions on mechanical and tribological responses are elaborated in support with micro structural examinations. Technical difficulties and latest innovations happened during the last decade in making Mg MMCs as high performance material are also presented.
PL
Stopy Ni-Co oraz kompozyty TiO2/Ni-Co osadzono elektrolitycznie z kąpieli siarczanowo-cytrynianowych o względnej zawartości jonów Co:Ni równej 1:49, 1:24 i 1:9 stosując gęstości prądu 2,5, 5 i 7,5 A/dm2. Wpływ parametrów osadzania na morfologię powierzchni, mikrostrukturę, skład chemiczny i skład fazowy zbadano za pomocą skaningowej i transmisyjnej mikroskopii elektronowej, spektroskopii dyspersji energii charakterystycznego promieniowania rentgenowskiego oraz dyfrakcji promieniowania rentgenowskiego. Wytworzone kompozyty charakteryzowały się globularną morfologią i nanokrystaliczną mikrostrukturą. Wykazano, że w osnowie kompozytów występują pojedyncze nanocząstki oraz aglomeraty TiO2. Zawartość TiO2 w kompozytach wynosiła około 4% mas. Stwierdzono, że wielkość ziarna kompozytów TiO2/Ni-Co zależy od obecności fazy umacniającej, warunków prądowych podczas osadzania oraz stężenia Co w osnowie Ni-Co.
EN
TiO2/Ni-Co composites were electrodeposited from citrate-sulfate bath with varying Ni:Co ratios. Effect of deposition conditions on chemical composition, surface morphology, microstructure and phase composition were investigated using scanning and transmission electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction. Manufactured composites were characterized by typical cauliflower surface morphology and nanocrystalline structure. Nanocrystalline TiO2 particles were embedded in the Ni-Co matrix both in the form of dispersive nanoparticles and clusters. The concentration of nc-TiO2 in composites was about 4 wt. %. Grain size of TiO2/Ni-Co composites depended on the content of strengthening phase, deposition current conditions and Co concentration in the Ni-Co matrix.
EN
The method of fabricating metal matrix composites plays a crucial role in obtaining dense materials characterized by high wear resistance. The present work describes an attempt to produce NiAl/CrB2 composites using the next generation spark plasma sintering (SPS) method, i.e. upgraded field assisted sintering technology (U-FAST) technique. Microstructure characterization was performed by means of scanning (SEM) and transmission (TEM) electron microscopy. The SEM microstructure investigations of the NiAl model material proved practically full densification of the material sintered at 1200°C and 1300°C, even if remnants of surplus nickel were observed at the boundaries of rounded NiAl grains. The NiAl/CrB2 composites, besides fused NiAl and CrB2 grains, showed the presence of a raised level of nickel also at the grain boundaries. The TEM microstructure observations helped to establish that even if the grain boundaries were pinned by nickel-rich precipitates, some increase in grain growth took place, as evidenced by the fact that strings of smaller precipitates were also visible outside the matrix grain boundaries. All these microstructure investigations indicate that the newly elaborated U-FAST technique is evidently capable of producing compacts free of porosity at lower temperatures and during a shorter time than solid hot pressing or vacuum sintering in a semiliquid state.
EN
In recent years, the composite materials have been very desirable by researchers for many engineering applications such as aviation and biomedical because of the tremendous characteristics of magnesium matrix metal composite. This current investigation aims to develop the AZ91/SiCp composites with various weight fractions (0, 2.5, 5 and 10 wt%) of silicon carbide particles via the stir casting method. The effect of SiC particles content on microstructure, mechanical and wear behaviour was investigated. The optical microscope, scanning electron microscopy and EDX analyses were utilized to detect the distribution of hard particles as well as the interface between the alloy and particles. Based on the findings, the homogeneous distribution of particles, refinement of grains in addition to good bonding between AZ91 alloy and particles have been achieved in produced composites. Therefore, the mechanical characteristics and wear performance are improved in composites compared with the unreinforced alloy. Moreover, these results suggest that for applications demanding high mechanical properties and wear resistance the AZ91/SiCp will be effective composites.
EN
Nonlinear properties of metal matrix composites (MMCs) are studied. The research combines results of loading–unloading tensile tests, microstructural observations and numerical predictions by means of micromechanical mean-field models. AA2124/SiC metal matrix composites with SiC particles, produced by the Aerospace Metal Composites Ltd. (AMC) are investigated. The aluminum matrix is reinforced with 17% and 25% of SiC particles. The best conditions to evaluate the current elastic stiffness modulus have been assessed. Tensile tests were carried out with consecutive unloading loops to obtain actual tensile modulus and study degradation of elastic properties of the composites. The microstructure examination by scanning electron microscopy (SEM) showed a variety of phenomena occurring during composite deformation and possible sources of elastic stiffness reduction and damage evolution have been indicated. Two micromechanical approaches, the incremental Mori–Tanaka (MT) and self-consistent (SC) schemes, are applied to estimate effective properties of the composites. The standard formulations are extended to take into account elasto-plasticity and damage development in the metal phase. The method of direct linearization performed for the tangent or secant stiffness moduli is formulated. Predictions of both approaches are compared with experimental results of tensile tests in the elastic–plastic regime. The question is addressed how to perform the micromechanical modelling if the actual stress–strain curve of metal matrix is unknown.
EN
Carbon with an amorphous structure was used as a component to modify the tribological properties of engineering plastics. Its construction allows the formation of carbon-based wear products during friction, adhesively bonded to the surface of cooperating machine parts, acting as a solid lubricant. The work compares the tribological properties of two groups of composites with an aluminium alloy matrix in which glassy carbon appeared in the form of particles and an open cell foam fulfilling the role of strengthening the matrix. The use of spatial structures of reinforcement provides, in comparison with the strengthening of particles, homogeneity of carbon distribution in the entire volume of the composite. The tests carried out on a pin-disc tester showed that the use of spatial carbon structures in the composite ensures a greater coefficient of friction stability than when reinforcing with particles, and the coefficient of friction with a small proportion of carbon foams (about 1 wt%) is comparable with the coefficient of friction in the contact with composites containing 5-10% carbon particles in granular form.
PL
Węgiel o strukturze amorficznej został wykorzystywany, jako komponent do modyfikacji właściwości tribologicznych tworzyw konstrukcyjnych. Jego budowa pozwala na tworzenie się w trakcie tarcia węglowych produktów zużycia, połączonych adhezyjnie z powierzchnią współpracujących części maszyn, pełniących funkcję smaru stałego. W pracy porównano właściwości tribologiczne dwóch grup kompozytów z osnową ze stopu aluminium, w których węgiel szklisty występował w postaci cząstek oraz piany otwartokomórkowej pełniącej rolę umocnienia osnowy. Wykorzystanie przestrzennych struktur zbrojenia zapewnia, w porównaniu z umocnieniem cząstkami, homogeniczność rozkładu węgla w całej objętości kompozytu. Przeprowadzone badania na testerze pin-disc wykazały, że wykorzystanie w kompozycie przestrzennych struktur węglowych zapewnia większą stabilność współczynnika tarcia niż przy umocnieniu cząstkami, a współczynnik tarcia przy niewielkim udziale pian węglowych (około 1% cz. wag.) jest porównywalny ze współczynnikiem tarcia w skojarzeniu z kompozytami zawierającymi 5–10% cząstek węglowych w postaci ziarnistej.
13
Content available Hybrydowa technologia HPDC&HSC
PL
W artykule przedstawiono rys historyczny oraz stan obecny technologii odlewania z wykorzystaniem ciśnienia zewnętrznego na przykładzie odlewania pod wysokim ciśnieniem (High Pressure Die Casting – HPDC) oraz prasowania w stanie ciekłym (Squeeze Casting – SC). Wykazano podobieństwa i różnice obu technologii oraz obszary wspólne, które zostały wykorzystane do budowy współczesnych, hybrydowych maszyn łączących cechy HPDC i SC. Ostatnie lata przyniosły rozwój konstrukcji maszyn ciśnieniowych, które umożliwiły hybrydyzację technologii z wysoką elastycznością procesu, polegającą na wyborze takiego sposobu przyłożenia ciśnienia zewnętrznego, w którym można pełniej wykorzystać jego wpływ jako czynnika termodynamicznego. Zaprezentowano doświadczenia w zakresie prasowania w stanie ciekłym i stało-ciekłym, uzyskane w badaniach prowadzonych w Instytucie Odlewnictwa w Krakowie.
EN
The article presents the history and current state of the technology of external pressure casting in the case of High Pressure Die Casting (HPDC) and Squeeze Casting (SC). The similarities and differences between the two technologies and the common areas that were used in the construction of modern hybrid machines combining the features of HPDC and SC were shown. Recent years have seen the development of pressure machine designs that have enabled the hybridisation of technologies with high flexibility of the process, consisting in the choice of such a method of applying external pressure in which its influence can be more effectively used as a thermodynamic factor. The following experiments were presented in the field of liquid and solid-liquid casting, obtained from research conducted at the Foundry Research Institute in Kraków.
EN
This research made an attempt to synthesize aluminum metal matrix composites through stir casting technique. The matrix material chosen in this study was AA7050 and the reinforcement material was ZrSiO4. The composites AA7050, AA7050-10%ZrSiO4, and AA7050-15%ZrSiO4 were used. The wear behavior of the aluminium matrix composites was investigated by using pin-on-disc tribometer. The advanced material has substantial development in tribological behavior when the reinforcement percentage is increased. From the experimental results, it was confirmed that sliding distance of 1200 m, applied load of 3 N and sliding speed of 2 m/s result in minimum wear loss and coefficient of friction, while adding 10%ZrSiO4 to the AA7050.
EN
The importance of second phase particles has received less attention for metal-matrix composites (MMCs) processed by one of the most common severe plastic deformation (SPD) techniques known as accumulative roll bonding (ARB). Accordingly, the present work has been dedicated to the processing and evaluating the effects of ARB on the tensile properties, work-hardening behavior, distribution of particles, and fracture surface appearance of a typical Al-B4C particulate composite. It was found that bonding between the reinforcement and the matrix is not good enough to grant the effective strengthening effect. As a result, both tensile strength and ductility of ARB processed aluminum were higher than those of ARB processed Al-B4C composite. Moreover, by increasing ARB pass number, the tensile strength and total elongation of composites increased, where the latter was related to the enhancement of particle distribution, improvement of the particle/matrix interface, and enhancement of the work-hardening behavior. It was revealed that particle distribution affects the ductility but its effect on the tensile strength is less pronounced.
EN
Cu-CNT composites were fabricated by a flake powder metallurgy method, and their microhardness, electrical conductivity, frictional and wear properties were investigated. Homogenous distribution of CNTs in fine-grained Cu matrix was obtained using this process. Microhardness increased with the addition of CNT vol% up to 8% to the Cu matrix, while the conductivity decreased to 79.2 IACS %. Results showed that CNTs play a major role in improving wear resistance by forming a CNT-rich film that acts as a solid lubricant layer. In the synthesized composites, Cu- 4 vol% CNT composite exhibited the best wear and friction properties. The dominant wear mechanisms for the Cu-CNT composites were plastic deformation, abrasion, and flake formation-spalling. Also, a newly modified correlation was proposed for the theoretical calculation of the friction coefficient of Cu-CNT composites consisting agglomerated CNTs.
EN
TiC particle-reinforced AISI 316L stainless-steel matrix composites were prepared using conventional powder metallurgy technology. The effect of TiC content on the microstructure and properties of these composites has been investigated with a particular emphasis upon hardness, wear resistance and corrosion resistance in sea water environments. The results showed that TiC particle reinforcement improved the hardness, wear resistance and corrosion resistance of AISI 316L stainless steel. The higher TiC content in the studied composites resulted in a higher hardness of the wear surface and a lower wear rate. The best corrosion resistance in sea water was achieved for sintered AISI 316L – 5% TiC composite.
PL
Konwencjonalną technologią metalurgii proszków wytworzono umacniane cząstkami TiC kompozyty o osnowie austenitycznej stali AISI 316L. Dokonano oceny wpływu udziału cząstek TiC na mikrostrukturę i właściwości tych kompozytów, w szczególności twardość, odporność na zużycie ścierne i odporność na korozję w środowisku wody morskiej. Stwierdzono, że umocnienie cząstkami TiC doprowadziło do poprawy twardości, odporności na zużycie ścierne i odporności na korozję stali AISI 316L. Wraz ze wzrostem udziału TiC w badanych kompozytach wzrastała twardość powierzchni zużycia, a malała jej szybkość. Natomiast najlepszą odporność na korozję w wodzie morskiej wykazał spiekany kompozyt AISI 316L – 5% TiC.
18
Content available remote Technological properties of metallic-diamond tools manufactured by SPS process
EN
This paper presents the results of the technological properties of impregnated diamond tools fabricated via spark plasma sintering (SPS) during the process of grinding and cutting of highpurity oxides ceramics (ZrO2) stabilized with Y2O3 or MgO. As a metal matrix the water atomized tin bronze and steel-based matrix was used. After sintering, an analysis of microstructure was conducted using scanning electron microscopy. The resulting materials were tested for the apparent density determined by Archimedes’ method, Rockwell hardness (scale B), Young’s modulus, as well as for the technological properties. The performance results of obtained diamond composites were compared with commercial diamond wheel fabricated by HP (hot pressing), usually employed in the grinding of ceramics. Results showed that diamond tools based on Cu-Sn and steel, obtained by SPS, may be successfully used as a matrix in the impregnated diamond tools for cutting or grinding of high-purity oxides ceramics.
PL
Przedstawiono wyniki badań właściwości fizycznych, mechanicznych i użytkowych narzędzi diamentowych wytworzonych metodą SPS (spark plasma sintering) w procesie szlifowania i cięcia półwyrobów z zaawansowanej ceramiki technicznej korundowej i cyrkonowej stabilizowanej tlenkiem itru (Y2O3) lub magnezu (MgO). Jako materiał osnowy zastosowano rozpylany wodą proszek brązu cynowego oraz stal stopową. Wykazano, że materiały zaproponowane na osnowę zapewniają uzyskanie wysokich właściwości użytkowych narzędzi diamentowych otrzymanych metodą SPS w porównaniu z narzędziami diamentowymi otrzymanymi metodą prasowania na gorąco (HP).
19
Content available remote Synthesis of metal matrix composites through stir casting process - a review
EN
Metal is the one of the important material in engineering materials because of their high strength to weight ratio. However the pure metals cannot be used as engineering materials due to their ductile property. So, to improve their mechanical properties, some of the high strength materials (not metals) were added as reinforcement to improve the mechanical properties of pure metals and the newly developed material is called as metal matrix composites. At present, Aluminium, Copper, Magnesium, Titanium and Iron have been used as matrix materials and materials like TiC, SiC, B4C, WC, Cr3C, TiO2, ZrO2, Gr, MoS2 and Si3N4 have been used as reinforcements. There are many processing techniques to fabricate metal matrix composites namely stir casting, ultra-sonic assisted casting, compo-casting, rheo casting, powder metallurgy technique, etc,. Among these, stir casting process is the most suitable and economical method to fabricate the metal matrix composites. In this article, an effort has been made to review the work of various researchers to fabricate metal matrix composites through stir casting process.
EN
The purpose of this paper is to elaborate on mechanical alloying conditions for a composite powder consisting of copper and brittle aluminium oxides. Detailed analysis of the Cu-Al2O3 powder mixture structure obtained in the mechanical alloying process allows for the study of the homogenization phenomena and for obtaining grains (in composite form) with a high degree of uniformity. The Cu-5vol.%Al2O3 composites were obtained by means of the spark plasma sintering technique. The results presented herein were studied and discussed in terms of the impact of using a different form of aluminium oxide powder and a different shape of copper powder on composite properties. Research methodology included microstructure analysis as well as its relation to the strength of Cu-Al2O3 interfaces. It transpires from the results presented below that the application of electrocorundum as a reinforcement phase in composites decreases porosity in the ceramic phase, thus improving thermal properties and interfacial strength.
first rewind previous Strona / 6 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.