炭素繊維ペーパー積層による炭素繊維/炭素複合材の製造

抄録

It was tried to prepare a carbon fiber reinforced carbon (CFRC) plate by the lamination of high performance carbon fiber (CF) paper.A carbon fiber reinforced plastics (CFRP) plate was prepared by laminating 80 sheets of the CF paper which was coated with phenol resin containing some amount of graphite powder, and carbonizing it into CFRC plate (3.5mm in thickness) at a temperature up to 1000°C under nitrogen (Fig.1).
The CFRC plate underwent the densification, high temperature and hot-press treatments to improve its mechanical strength. The densification treatment did not improve the mechanical strength of the CFRC plate (Table 1).While, by the high temperature treatment (1500°C, 2200°C, and 2500°C), the flexural and shear strength of the CFRC plate remarkably increased and the modulus slightly decreased.The maximum flexural strength was obtained at 2200°C of HTT (Table 2).The thickness of CFRC plate decreased from 3.5mm to 3.2mm with the increase of the treatment temperature from 1000°C to 2500°C (Fig.4).The X-ray diffraction profiles of the CFRC indicated the growth of graphitic structure at the temperature over 2200°C (Fig.7).It suggests that the shrinkage of CFRC plate was due to the structural change of the matrix and CF by stress graphitization.
By hot-press treatment (2200°C, 140kg/cm²), the thickness of CFRC plate decreased from 3.5mm to 2.5mm, the bulk density increased to 1.78, the porosity decreased to 12%, and the cross section texture became more homogeneous than that before the treatment.The mechanical properties of this CFRC plate was 150MPa in flexural strength, 39GPa in flexural modulus, and 200MPa in compressive strength, and these values obtained show narrower scatter than that in other cases (Table 2).On the bases of the best properties previously obtained on UD-CFRC samples and of the results in this work, it was assumed that the maximum value of quasi-isotropic CFRC plate is 150-200MPa in flexural strength.