C Sauder et al./ Composites Science and Technology 62(2002 )499-504 0,70 0,50 古 0,00 10001200 Temperature(C) Fig. 7. Structure of an ex-PAN fibre [8] Fig 4. Longitudinal thermal expansion at various temperature for a tungsten fibre(d=18 um) 0. 3 expansion coefficient for 1600/C treated fibre a expansion coefficient for 2200C treated fibre_.'p Experimental points g cal fit 100o Temperature(K) Fig. 5. Longitudinal thermal expansion at various temperatures for a PAN-based fibre 0.8 1 o untreated fibre strain Experimental points 8 - 1600C treated fibre strain 20 Theoretical fit 1600C treated fibre expansion coefficient 6 1000 3000 2200C treated fibre expansion Temperature(K sion⑨9 of thermal expansions of single crystal in the transverse and in the longitudinal directions. Indeed if orientation of BsU was parallel to fibre axis, the expansion of fibre would be close to that indicated by aa. However, at temperatures above 1000C the coefficient of thermal expansion still increases, which suggests that bsU are 4008001200160020002400 not perfectly oriented parallel to fibre axis and that ac Fig. 6. Longitudinal thermal expansion at various temperatures a governs thermal expansion in the longitudinal direction This phenomenon is particularly significant at tempera rayon-based fibre tures above 1000C. At these temperature ae increasesof thermal expansions of single crystal in the transverse and in the longitudinal directions. Indeed, if orientation of BSU was parallel to fibre axis, the expansion of fibre would be close to that indicated by a. However, at temperatures above 1000
C the coefficient of thermal expansion still increases, which suggests that BSU are not perfectly oriented parallel to fibre axis and that c governs thermal expansion in the longitudinal direction. This phenomenon is particularly significant at tempera￾tures above 1000
C. At these temperature c increases Fig. 4. Longitudinal thermal expansion at various temperature for a tungsten fibre (d=18 mm). Fig. 5. Longitudinal thermal expansion at various temperatures for a PAN-based fibre. Fig. 6. Longitudinal thermal expansion at various temperatures for a rayon-based fibre. Fig. 7. Structure of an ex-PAN fibre [8]. Fig. 8. Bulk graphite thermal expansion [9]. 502 C. Sauder et al. / Composites Science and Technology 62 (2002) 499–504