Studies On Catalytic Graphitization Of Carbon Materials

Carbon materials have attacted tremendous attention due to their high strength, high modulus, resistance of heat and chemical corrosion, anti-friction, electronics conductivity, thermal conductivity, anti-radiation, good damper, shock absorption, noise reduction, also are the ideal resistant ablation, the structural and functional composite material element; Phenolic resin is easy for raw materials, low cost, heat-resistant, resistant to erosion, and is commonly used in composite material as a matrix resin. They are widely used in in different fiels, such as aerospace, defense industry and other advanced fields, also used high-level sports recreation supplies, medical equipments, machinery, transportation and other civilian industry. The performances of carbon material are closely associated with crystal degree, microstructure, macrostructure and surface characteristics. Carbon can transform from disorder to order structure by heat treatment. Many efforts indicated that improving graphitization at lower temperature or increasing the graphitization degree by adding either organic or inorganic chemical additive which called catalytic graphitization. Therefore, the catalyzed graphitization is the key point of carbon material research. Based on this, this paper has studed the catalyzed graphitization of carbon fibers and the carbon fiber reinforced phenolic resin composites by electroless plating and electroplating. The details are summarized as follows:(1) Effect of fiber splitting on the catalytic graphitization of electroless Ni–B-coated polyacrylonitrile (PAN)-based carbon fibers: The anodization and SnCl₂ sensitization + PdCl₂ activation were to pretreated the carbon fibers. The effects of anodization treatment and Ni-B catalysts on the graphitization of PAN-based carbon fibers was investigated. The morphology changes of carbon fibers were observed by SEM. The structure changes of carbon fibers were characterized by X-ray diffraction and Raman spectroscopy, both of which indicated that the graphitization of PAN-based carbon fibers were accelerated by both anodization treatment and Ni-B catalysts.(2) Catalytic graphitization of PAN-based carbon fibers by electroplating Ni-Co: The catalytic graphitization of anodized PAN-based carbon fibers in the presence of Ni-Co was investigated. The catalysts of Ni and Co were investigated on the catalytic graphitization of carbon fibers compared with Ni-Co. The binary Ni-Co catalyst shows a higher catalytic effect in the graphitization of PAN-based carbon fibers than single Ni or Co, with a d002 of 0.3359 nm and Lc(002) of 31.02 nm at a heat of treatment of 2400°C. The method of catalytic graphitization by Ni-Co is simple and the graphitization is better , so it can developed to catalyzed the C/C composites graphitization.(3) Catalytic graphitization of PAN-based carbon fiber reinforced phenolic resin composites by Ti-B: A sol-gel synthesis method was used to modify a Ti-B coating on the surface of PAN-based carbon fibers and then to prepared the carbon fibers reinforced phenolic resin composites. The surface morphology of carbon fibers was observed by SEM. The interface of carbon fiber and the resin combined uniformly inseparablely. The structural changes of the graphitized composites were characterized by Raman spectrum and XRD. The effects of the Ti-B on the graphitization of carbon fibers reinforced phenolic resin composites were investigated. The reseach showed the catalytic effect of Ti-B was obivious. The highest catalytic graphitization effect is achieved in treating the PAN-Based fibers using Ti-B sol-gel, with 2400°C heating resulting in a d002 of 0.3363 nm. This paper was established the base for research the relationship between the graphitiztion and the mechanical properties of carbon fibers reinforced phenolic resin composites.