Rozszerzalność cieplna kompozytów na osnowie stopu aluminium umacnianych włóknami Al2O3 oraz grafitem

• Autorzy: Naplocha K. , Granat K. , Janus A.

Warianty tytułu

EN

Thermal expansion behavior of aluminium matrix composites reinforced with Al2O3 fibres and graphite

• Języki publikacji: PL

Abstrakty

PL

Zastosowano odlewanie w stanie ciekłym do nasycania stopem EN-AC AlSi7Mg porowatych kształtek ceramicznych wykonanych z włókien Saffil oraz grafitu w formie włókien lub płatków. Uzyskano w miarę jednorodną strukturę kompozytu, choć natrafiono na trudności z równomiernym wymieszaniem włókien Saffil z włóknami grafitowymi. Nie zaobserwowano produktów reakcji chemicznych na granicy grafit-osnowa, która rozdzielała raczej słabo związane składniki kompozytu. Badania rozszerzalności prowadzono w zakresie 20-300°C, wykonując 3 cykle cieplne. W pierwszym cyklu obserwowano wyraźną histerezę oraz trwałe odkształcenie, które zanikały w kolejnych cyklach. Udział włókien Saffil ogranicza rozszerzanie się aluminiowej osnowy szczególnie w podwyższonych temperaturach. W kolejnych cyklach osiągnięcie granicy plastyczności osnowy przez naprężenia następuje w coraz wyższych temperaturach. Wzrost zawartości umocnienia przyczynia się do zmniejszenia współczynnika rozszerzalności liniowej w całym zakresie pomiarowym. Włókna Saffil tworzą szkieletową konstrukcję hamującą rozrost osnowy, natomiast grafit sprzyja relaksacji naprężeń.

EN

Thermal expansion behavior of aluminium matrix composite reinforced with alumina fibres and graphite have been reported. Preforms were infiltrated using direct squeeze casting method to produce composite with about 6.5-15.0 vol. % Al2O3 fibres (Saffil) and 1.5-12.0 vol. % graphite in form of flakes or fibers. Porous preforms with good permeability and appropriate strength reveal semi-oriented arrangement of fibres and graphite flakes. Binder o the base of silica was used to join alumina fibres and harden preform. The composite microstructures exhibit regular arrangement of alumina fibres with graphite flakes. Some problems with stirring of both types of fibres needed to incorporate extra operation during preform production. Observation of composite fracture revels that graphite-matrix bonds are rather weak and interface was free of any visible chemical reaction products. Tests of thermal expansion were carried out using direct dilatometric apparatus in 20-300°C temperature range. For all composite samples first heating-cooling cycle curve runs with hysteresis loop leaving residual strain. It was especially evident for composites with low graphite content. The mismatch in thermal expansion coefficient CTE could introduce large stresses during manufacturing and correspondingly increase the dislocation density. This mismatch leads to compressive and tensile stresses during heating, respectively in matrix and reinforcement. After next cycles hysteresis slowly reduce due to relaxation of residual stresses and plastic deformation of the matrix. Comparison of strain-temperature curve for monolithic Al-Si7 alloy and its composites reveals that alumina fibres considerably constrain thermal expansion and addition of graphite slightly intensifies this effect. On the basis of strain results thermal expansion coefficients were calculate for all three cycles. The CTE increases with the temperature increasing, reaches a maximum and than decrease again. Thorough analyse of curve shape allows to ascertain that after each cycle this point of maximum moves towards the high temperature. It marks the moment when the stresses overcome the yield strength and plastic deformation of matrix occurs. Reinforcing of matrix with Saffil fibres results in decreasing of CTE especially in higher temperature range. Probably fibres which form rigid preforms constrain expansion of the matrix that becomes more plastic at higher temperature. Addition of graphite slightly decreases values of CTE over entire temperature range irrespectively is it fibres or flakes. Differences between composites reinforced with various amount of alumina and graphite show that the reduction effect on CTE is enhanced when alumina fibres content increases and graphite decreases.

Słowa kluczowe

PL

kompozyt; włókno; grafit; rozszerzalność cieplna

EN

composite; fibre; graphite; thermal expansion

• Wydawca: Wydawnictwo Politechniki Częstochowskiej
• Czasopismo: Kompozyty
• Rocznik: 2007
• Tom: R. 7, nr 2
• Strony: 76--82
• Opis fizyczny: Bibliogr. 21 poz., rys.

Twórcy

autor

Naplocha K.

autor

Granat K.

autor

Janus A.

• Politechnika Wrocławska, Instytut Technologii Maszyn i Automatyzacji, ul. Łukasiewicza 3/5, 50-371 Wrocław,

Bibliografia

• [1] Huang Y.D., Hort N., Kainer K.U., Thermal behavior of short fiber reinforced AlSi12CuMgNi piston alloy, Composites 2004, A35, 249-263.
• [2] Herr A.E., Sridhar Canumalla, Pangborn R.N., Thermal fatigue of squeeze cast, discontinuous alumina-silicate fiber-reinforced aluminum alloy (A356) composite, Materials Science and Engineering 1995, A200, 181-191.
• [3] Subodh Kumar, Sudeep Ingole, Hajo Dieringa, Karl-Ulrich Kainer, Analysis of thermal cycling curves of short fibre reinforced Mg-MMCs, Composites Science and Technology 2003,63,1805-1814.
• [4] Huang Y.D., Hort N., Dieringa H., Kainer K.U., Analysis of instantaneous thermal expansion coefficient curve during thermal cycling in short fiber reinforced AlSi12CuMgNi composites, Composites Science and Technology 2005, 65, 137-147.
• [5] Subodh Kumar, Ashok Kumar Mondal, Hajo Dieringa, Karl-Ulrich Kainer, Analysing hysteresis and residual strains in thermal cycling curves of short fibre reinforced Mg--MMCs, Composites Science and Technology 2004, 64, 1179-189.
• [6] Huang Y.D., Hort N., Dieringa H., Maier P., Kainer K.U., Investigations on thermal fatigue of aluminum-and magnesium-alloy based composites, International Journal of Fatigue 2006, 28, 1399-1405.
• [7] Badini C, Fino P., Musso M., Dinardo P., Thermal fatigue behaviour of a 2014/Al2O3-SiO2 (Saffil ® fibers) composite processed by squeeze casting, Materials Chemistry and Physics 2000, 64, 247-255.
• [8] Carreno-Morelli E., Urreta S.E., Schaller R., Mechanical spectroscopy of thermal stress relaxation at metal-ceramic interfaces in aluminum-based composites, Acta Materialia 2000, 48, 4725-4733.
• [9] Qiang Zhang, Gaohui Wu, Longtao Jiang, Guoqin Chen, Thermal expansion and dimensional stability of Al-Si matrix composite reinforced with high content SiC, Materials Chemistry and Physics 2003, 82, 780-785.
• [10] Huang Y.D., Hort N., Dieringa H., Kainer K.U., Liu Y.L., Microstructural investigations of interfaces in short fiber reinforced AlSi12CuMgNi composites, Acta Materialia 2005, 53, 3913-3923.
• [11] Wu S.Q., Wei Z.S., Tjong S.C., The mechanical and thermal expansion behavior of an Al-Si alloy composite reinforced with potassium titanate whisker, Composites Science and Technology 2000, 60, 2873-2880.
• [12] Pedersen L.M., Bentzen J.J., Bramsø N., Dimensional response of metal matrix graphite particle composites to sintering, Scripta Materiala 2001, 44, 743-749.
• [13] Skirl S., Hoffmant M., Bowmans K., Wiederhornp S., Rddel J., Thermal expansion behavior and macrostrain of Al203/Al composites with interpenetrating networks, Acta Metallurgica 1998, 46, 7, 2493-2499.
• [14] Ted Guo M.L., Tsao Chi.-Y.A., Tribological behavior of aluminium/SiC/nickel- coated graphite hybrid composites., Materials Science and Engineering 2002, A333, 134-145.
• [15] Etter T., Papakyriacou M., Schulz P., Uggowitzer P.J., Physical properties of grphite/aluminium composites produced by gas pressure infiltration method, Carbon 2003, 41, 1017--1024.
• [16] Skoczkowski K., Technologia produkcji wyrobów węglowo-grafitowych, Śląskie Wydawnictwo Techniczne, Katowice 1995.
• [17] Pelleg J., Ashkenazi D., Ganor M., The influence of a thud element on the interface reactions in metal-matrix composites (MMC): Al-graphite system, Materials Science and Engineering 2000, A281, 239-247.
• [18] Myalski J., Śleziona J., Kompozyty metalowe zbrojone cząstkami węgla szklistego, Przegląd Odlewnictwa 2005, 1, 24-33.
• [19] Landry K., Kalogeropoulou S., Eustathopoulos N., Wettability of carbon by aluminum and aluminum alloys, Materials Science and Engineering 1998, A254, 99-111.
• [20] Książek M., Sobczak N., Mikulowski B., Radziwill W., Surowiak I., Wetting and bonding strength in Al2O3 system, Materials Science and Engineering 2002, A324, 162-167.
• [21] Dezellus O., Eustathopoulos N., The role of Van der Waals interactions on wetting and adhesion in metal/carbon systems, Scripta Materialia 1999, 40, 11, 1283-1288.