Characterization And Property Analysis Of HKT800 Carbon Fiber And Its Composite

The carbon fibers reinforced composites are widely used in aerospace, enginery,marine and automobile industries due to their outstanding properties such as high specific strength and stiffness, lower density and flexible designs. Carbon fiber has become one of the main reinforced fiber of advanced composite materials. With continuous requirements increase in various application areas of carbon fiber reinforced composite material, high-strength carbon fiber products have been developed from T300 to T700, T800 and T1000. Currently, T300, T700 and other common grade carbon fibers have been widely studie d and applied in China.However, related research and application of T800 as well as other high-performance carbon fibers made in China have rarely been reported due to the reason that these products have not been achieved in industrial production before.HK T800 carbon fiber as the first industrialization production of T800 grade carbon fiber, has been achieved a stable production, filled the domestic blank of high-performance carbon fiber. But for the domestic T800 carbon fiber products,there is no systematic characterization and property analysis for it and its composite up to now. In view of this situation, a detailed characterization of the performance of HK T800 carbon fiber, from macro-scope to microcosmic system is analyzed, and the original preparation AG80 composite resin system has been optimized, and then the performance of the composite materials are verified by wet process. With the help of a professional institution, the perfor mance of HK T800 carbon fiber composites has been analyzed syste matically, and then some composite sample made by winding process are tested.The char acterization and analysis on the HK T800 carbon fiber were performed by SEM, XPS, FTIR and Raman, etc. Tensile strength and modulus of HK T800 carbon fiber reached 5.63 GPa and 292 GPa respectively, and the Cv values of all index were less than 5 %, which indicated good stability. Sur face activity of 6K carbon fibers was higher than 12 K carbon fibers with same type, which was attributed to the different size. A large number of grooves were distributed on the surface of the carbon fibers, which caused by the wet spinning and the surface treatment process. Small amounts of HK T800 carbon fiber swere cashew type. The crysta lline size on the surface of HK T800 carbon fiber was very small, and there were a lot of unsaturated carbon atoms on the surface. The layer of HK T800 carbon fiber and Toray T800 carbon fiber was consistent, all were 3.47 ?, but FWHM was lower, stack size and molecular orientation were slightly higher than the Toray T800.The porosity of HK T800 carbon fiber calculated by WAXD was 17.4%. The porelength, microporous cross-section average cuttingline length and micropore volume of HK T800 carbon fiber were lower than Toray T800 carbon fiber. The sizing agentcont aining of HK T800 carbon fiber was epoxy resin, single fiber diameter was about5 μm, and the ash content was about 0.1%.The influence of DDS as curing agent and BF3? MEA as accelerator dosing during AG80 curing reaction has been invest igated by DSC(Differential Scanning Calorimetry) method. Also the rheological test has been performed for comparis on and analysis. The results indicated that: during AG80 curing reaction, when simply using DDS as curing agent, the reaction tempe rature would be much higher than what we desired. Once BF 3? MEA was using as curing acceler ator, the reaction temper ature of AG80/ DDS system could be decreased much effectively. When the critical massratio of 100 : 30 : 3 for AG80, DDS and BF3? MEA was performed during the reaction, the peak temper ature of DSC cure indicated as 154 ℃. The inter section point of G " and G’ has been test ed as 150 ℃ by rheomet er, which showed the results met the objective demand accordingly.Based on the study of the carbon fiber and resin matrix, HK T800 carbon fiber /A G80 epoxy resin composite material was prepared by wet process, and its mechanical propert ies and its interface were analyzed. When The fiber volume fraction was 62 %, and the tensile, flexural and compression strength of HK T800 carbon fiber/ AG 80 epoxy resin composite were 2662 MPa, 1874 MPa and 1639 MPa, inter layer shear strengt h was 110 MPa, reached the level of Toray T800 carbonfiber composites performance. But the mechanical properties, especially the tensile strengt h, compared with the overseas same grade carbon fiber composite materials still had a little gap. The inter face combination of composite material also existed some shortage, which still need furt her improvement.A serie s of HK T800 carbon fiber composit e materials were prepared with the help of a professional institution, where the performance of these composite had been tested. HK T800 carbon fiber reinforced BMI resin matrix composites were superior to the epoxy resin matrix composites. The mechanical performance of all HK T800 carbon fiber reinforced BMI resin matrix composites had reached higher level. But the performance of the epoxy resin matrix composite was poor compared wit h BMI. Then matrix resin for mula and surface state of the carbon fiber were optimized. The tensile strength of HK T800 carbon fiber epoxy resin matrix composites reached 2521 MPa. CAI reached 325 MPa. Other properties of composite all reached the level of Toray T800 carbon fiber. But the conversion rate of carbon fiber strength was still low, resin matrix and the interface of composite still need to be further optimized. There were lots of affect factors about the performance of carbon fiber resin matrix composites, such as carbon fiber properties and its surface behavior, resinperfor mance and the matching behavior with carbon fiber,interface of the composites and so on. In order to achieve the best conversion of carbon fiber in mechanical performance, specific issues still need to be analyzed, so as to masterthe improvement direction.A variety of HK T800 carbon fiber composite sample made by winding technology were tested. All products indicated the advantages of HK T800 carbon fiber. Conversion rate of the mechanical properties could achieve above 80%, which met the technical conditions of product development and the application requirements. Under the same winding process condition, the performance of composite with different resin system had obvious differences, which showed that the resin played animpor tant role in carbon fiber composite. KH resin system,deve loped specially for HK T800 carbon fiber, could ensure the mechanical properties of composite, also had a very huge promotion compared with other resinsystem supporting T700 carbon fiber. Winding process played more import ant role in molding process, the process parameters need to be adjusted according to the different carbon fiber products and the matrixresin, to guarantee more effective performance of composite.