Microstructure and densification of 3D weaving preform

Abstract

The carbon fiber preform is the skeleton of the carbon/carbon material. During the densification process,the pores of the preform is filled by the matrix carbon to form a carbon/carbon composite material. In order to explore the relationship between the microstructure of carbon fiber preform and densification, three kinds of three-dimensional woven preforms were used as the research objects. The microstructure of the preform was observed through a metallurgical microscope, and digital models of the theoretical structure of the preforms were established to calculate the volume content of different types of pores in the body, and to study the effect of pore structure on the densification efficiency of chemical vapor deposition. The results show that the pores in the three-dimensional woven preform are periodically and repeatedly arranged. The fiber volume fraction in the preform is related to the XY fiber layer spacing and the Z direction fiber spacing, the smaller the XY fiber layer spacing and the Z direction fiber spacing are, the higher the fiber volume content of the preform is; the preform is mainly composed of the pores in the fiber bundle and the inter-bundle pores surrounded by the X, Y, Z fiber bundles; the pore size and structure of the preform affect the densification efficiency, and the densification rate of the preform with high porosity is higher in the early stage of densification, and the preform with uniform pore structure gains weight quickly in the later stage of densification.

Keywords

• carbon fiber preform
• pore structure
• porosity
• cvi densification
• structural model