The Thermal Conductivity Determination And Structure Research Of High Thermal Conductivity Pitch Based Carbon Fiber

High performance carbon fibers from mesophase pitch which through a series ofprocessing, get the carbon fiber has high thermal conductivity, because of hightemperature resistance and good conductivity and excellent performance has beenwidely applied the in the space, aerospace, electronic industry and other fields.Inrecent years,the high thermal conductivity carbon fiber has become an importantdirection in the carbon fiber research field. At present, it have seldom reported aboutstudy the precise relationship of the high thermal conductivity carbon fiber crosssection structure and thermal properties. Carry out accurate research of relationship ofthermal conductivity and structure in carbon fiber,it’s great significance to the highthermal conductivity carbon fiber’s development.In this paper, the circuit plate four point method as the main method for indirectdetermination of thermal conductivity of carbon fiber. On the circuit plate four pointmethod and train of thought is introduced in this paper, and the test influence factorsare analyzed to discuss. Use T300, M40, PE three industrial fiber as standard sampleby the circuit plate four point method to test the accuracy and repeatability ofverification. Study of PE fiber diameter and thermal conductivity; by using scanningelectron microscopy and Raman spectrμm analyzer series of HUNKF graphite fiberstructure, thermal property,graphite degree was studied. Focus on the analysis offiber diameter, cross section structure and thermal conductivity and high thermalconductivity of pitch based carbon fibers, graphite degree, structure and thermalconductivity of the relationship between the three. Taking KF519D as samples,analyzes the position of fiber Raman analysis effect R value of Determination.The principle of circuit board type four point method for carbon fiber thermalconductivity measurement is: carbon materials thermal conductivity and resistivityhave a very strong correlation. Circuit board type four point method for thedetermination of thermal conductivity is simply and easy to operate, which cangreatly improve efficiency of the carbon fiber thermal conductivity test. Throughdeterminate the T300, M40, PE three industrial fiber’s electrical resistance, provedcircuit plate four point method has good repeatability and accuracy, can be used forindirect determination of thermal conductivity of carbon fiber.The factors influence circuit board type four point method’s accuracy are: the time for conductive adhesive curing, conductive adhesive composition and quality,carbon fiber filament structure dispersion. Conductive adhesive curing time have agreater impact on the testing results, cured at room temperature for1hours, increasethe curing temperature can promote the conductive adhesive curing. Conductiveadhesive composition and quality affect measuring accuracy, using small resistivityconductive adhesive can effectively improve the test precision. Carbon fiber filamentdiameter and cross section structure’s discretion has effect on the test results’discretion.Carbon fiber diameter, cross section structure and graphite degree effect on itsthermal performance. The diameter of carbon fiber effect fiber’s thermal conductivity:diameter change in a small range, then the diameter is increased thermal conductivitywas slightly decreased, when the diameter is varied within a larger range, werecontrary to law; Carbon fiber cross sectional structure more clear, density, thermalconductivity is higher, and vice versa. Raman spectral analysis different position ofcarbon fibers, The R value of the determination results will different, generallyperpendicular to the fiber direction determination of graphite sheets will get lowest R.Graphite sheets with clarity and whole fibers graphitization degree, overallgraphitization degree more high, graphite sheet more clear,there is no correlation ofgraphite sheet density and fiber graphitization degree.