C/Al複合体の界面反応とその引張強度への影響

抄録

Interfacial reaction between PAN (Polyachrilonitrile) based and Pitch based carbon fibers and pure aluminium was investigated. The C/Al composite was prepared by depositing aluminium on the surface of carbon fiber in vacuum. The degradation in the tensile strength of C/Al composites was associated with interfacial reaction product, which is aluminium carbide (Al₄C₃). Al₄C₃ was observed by transmission electron microscope (TEM) after heat treatment of C/Al composites.
Experimental results is as follows;
(1) The reactivity at the interface between carbon fiber and aluminium differed with the surface structure change, . which ascribes to the internal structure of fiber.
(2) The intrinsic crack length (C₀) in C/Al composites can be calculated from the relation between the thickness of reaction product and the tensile strength. These values were 0.036 μm and 0.049 μm of PAN based and Pitch based C/Al composites respectively. The relation between the tensile strength (σ) of composite and the thickness of reaction product (X) can also be expressed as follows, σ= K/(X)^1/2, where K is proportional constant. K_PAN = 66.4 × 10³ [ kg· m^-3/2] K/_Pitch = 70.8 × 10³ [kg· m^-3/2]
(3) The activation energy for the formation of Al₄C₃ at the interface was 63 kcal/mol for PAN based carbon fiber and 82 kcal/mol for Pitch based carbon fiber. These results suggest that the reactivity of PAN based carbon fiber is high in comparison with that of Pitch based carbon fiber at the interface. The high reactivity must be due to the amount of edge carbon atoms on the fiber surface.