⩧ Ṏ 姗 㒈 墂 㓩Fabrication of Copper Plated Carbon Fiber Dispersed Iron Matrix Composites and Thermal
Conductivity Calculation by Two-Dimensional Microstructure Images
澻㖡ࡵࡗࡁⅣ⣲⧄⥔ࢆῧຍࡋࡓ㕲ᇶ」ྜᮦᩱࡢస〇࡜஧ḟඖᚤ⣽ᵓ㐀⏬ീࢆ⏝࠸ࡓ⇕ఏᑟ⋡ࡢィ⟬)㬐 ⌎ WU DICarbon fiber (Cf) contacts and reacts with pure iron, and Cf requires electroless copper plating
to protect Cf from being destroyed. Copper-coated carbon fiber (Cf -Cu) can establish thermal
conduction channels in composite materials to accelerate heat transfer. The time of heat conduction
accounts for 1/3 of the cycle of hot stamping die production of auto parts. The addition of Cf -Cu
can accelerate the heat conduction of SKD61 (40CrMoV5) alloy, improve the thermal conductivity(TC) of the composite material, and quickly produce thinner and higher strength (≥1000MPa) autoparts, which can not only effectively reduce the weight of the car body, reduce fuel consumption,
improve vehicle safety and comfort, and can reduce molding pressure, reduce deformation and wear,
and prolong the service life of the mold. Cf -Cu is highly anisotropic, and its orientation has a strong
influence on mechanics and TC. Controlling the orientation of Cf -Cu becomes the core of improving
the TC of composite materials. The impurity atoms in the SKD61 (40CrMoV5) alloy, the voids
created by the fabrication of the composite, the orientation and aspect ratio of Cf-Cu, andexperimental errors all hinder heat conduction.
This study (Chapter 2) firstly explored the mechanical properties and TC of Cf -Cu/Fecomposites. When the sintering temperature was less than 1100K, Cf -Cu was not destroyed andcarbides were not formed. When the volume fraction of Cf -Cu in the composite increased from 20%
to 30%, the relative density decreased sharply with the increase of Cf -Cu, and the mechanicalproperties and TC of the composite decreased. In Chapter 3, 5-25vol.% Cf -Cu/Fe composites were
hot-rolled to align most of the Cf -Cu along the direction of heat flow and improve the TC of thecomposites. The mathematical model of Cf -Cu in three-dimensional space was established, and therelationship between the orientation of Cf -Cu on the two-dimensional section and the orientation inthree-dimensional space was obtained. By 2D image analysis, the simulated TC of the composite
shows good agreement with the measured TC. In Chapter 4, various factors hinder the heat transfer
in 5-25vol.% Cf -Cu/Fe composites were investigated. By comparing TC calculated from ROM,
EMA model, 2D image analysis, and steady-state method, the degree to which the voids, aspectratio, and orientation of Cf -Cu and experimental errors affect TC was determined. The main factors
hindering TC are the aspect ratio and orientation of Cf -Cu. For 20% Cf -Cu/Fe, the contact thermal
resistance and the decrease of TC of negative Cf -Cu offset the increase of TC of positive Cf -Cu,and both the simulated and measured TC reached the maximum value, 68.89 Wm for −1K-1 and71.02 Wm-1K-1, respectively. In Chapter 5, in order to improve the TC of SKD61(40CrMoV5)
alloy, considering the void, aspect ratio, and orientation of Cf-Cu (Chapter 4), 2D image analysis(Chapter 3) was used to evaluate the TC of Cf -Cu/SKD61 (40CrMoV5) composite. Compared withthe SKD61 (40CrMoV5) alloy, the TC of the Cf -Cu/SKD61 (40CrMoV5) composite was increased
by 91%. This thesis lays the foundation for the study of Cf -Cu reinforced metal matrix composites
TC. The TC of the composite material of SKD61 (40CrMoV5) can be effectively improved byadding Cf-Cu.