Journal of the European Ceramic Society 14 (1994) 441M46 Thermal and Elastic Properties Carbide Whisker Composites of Alumina-Silicon Luciano Fabbri,* Ernesto Scaf6 & Giancarlo Dinelliht "Eniricerche SpA, Monterotondo, Roma 00016, Italy J'Temav CE.R1.VE., P. Marghera VE 30175, Italy (Received 30 November 1993: revised version received 13 May 1994; accepted 24 May 1994) Abstract The study described in this paper is specifically related to the thermal and elastic properties of AI:Oj matrix with SiC whisker reinforcements. Measure- ments of Young ~ modulus and thermal diffusivity/ comhu'tivi O' were performed on various AI:07SiC w compositions obtained by varying both the raw materials and the whisker volume .fractions. While the Young ~' modulus was quite independent of the choice of raw materials, a remarkable difference was found for the thermal conductivity of composites processed with diff'erent whisker sources. In dieser Veri~bntliehung werden Ergebnisse zu den thermisehen und elastischen Eigenschaften einer ALO3-Matrix mit SiC-Einkristallverstdrkungen vorgestellt. Messungen des Elasizitdtsmodulus sowie der thermischen Diffusivitdit/LeitfOhigkeit wurden an verschiedenen Al,O3-SiC,.-Zusammensetzungen durchgefiihrt. Dabei wurden die" Volumenanteile sowohl des Tr6germaterials als auch der Ein- kristalleinlagerungen verdndert. Es ergab sich, daft der ElasizitOtsmodulus unabh6ngig yon der Wahl des Triigermaterials ist, wiihrend sich die thermische Lei(/~ihigkeit der Verbindungen mit unterschied- lichen Einkristalleinlagerungen signifikant unter- scheidet. L 'Otude de;trite dans eet article porte sur les pro- priOt~;s thermiques et Olastiques d'une matriee Al20~ renforeOe par des whiskers de SIC,,.. Des mesures du module d'Young, de la diJfusivitO/conductivitO thermique ont OtO effectuOes pour plusieurs composi- tions de AI20~-SiC ., obtenues en Jaisant varier gl la fois les matOriaux de base et les fractions volu- miques de whiskers. Alors que le module de Young * Present address: Commissionof the European Communities, Joint ResearchCentre, Institute for Advanced Materials, Ispra Establishment, 21020 Ispra (VA) Italy. t Present address: Refel SpA, S. Vito Tagliamento (PM) 33078 Italy. semble relativement indOpendant du choix des matOriaux de base, on note un ~;cart remarquable pour la conductivitO thermique des composites fabriquOs h partir de difj&entes origines de whiskers. I Introduction 441 In the last few years, a strong effort has been devoted to the development of ceramic matrix composites with fibre, particulate or whisker reinforcements. 12 The driving force has been the improvement in mechanical properties of mono- lithic ceramics, in order to obtain an enhanced fracture toughness and greater reliability. Several mechanisms have been proposed to explain the observed toughening: crack deflection, pull-out, micro-crack formation, etc. In contrasL less atten- tion has been paid to the thermal and elastic prop- erties, which are critical in the material design for high temperature applications. Nevertheless, the addition of a second phase in a monolithic ceramic can change significantly not only the fracture behaviour but also a different set of properties named 'field properties '3 such as the thermal con- ductivity, thermal expansion and elastic moduli. 4 9 Alumina-SiC whisker composites (AI2OwSiC,,) have received particular attention due to their successful application as cutting tools. "1'1~ In all these applications the thermal conductivity must be as high as possible in order to reduce thermal shock failures. As is well known, the heat transfer properties strongly depend upon the purity level of the crystal lattice of the grains. Thus, a greater control of impurities, originating both from the raw materials and the processing conditions, has to be obtained. In this paper, AI203-SiC w composites prepared by varying the raw material sources and process- ing times were studied. Different compositions for each specimen were obtained by varying the Journal of the European Ceramic SocieO~ 0955-2219/94/$7.00 © 1994 Elsevier Science Limited, England. Printed in Great Britain