Effect of chromium carbide coating on thermal properties of short graphite fiber/Al composites

Abstract

A chromium carbide coating was synthesized onto graphite fibers by molten salts method to improve the interfacial bonding and thermal properties of short graphite fiber/Al composites which were fabricated by vacuum pressure infiltration technique. The graphite fiber/Al composites with different thicknesses of chromium carbide coatings were prepared through varying plating times to investigate the influence of chromium carbide layer on the microstructures and thermal properties of the composites. The combined Maxwell-Garnett effective medium approach and acoustic mismatch model schemes were used to theoretically predict thermal conductivities of the composites. The results indicated that the chromium carbide coating formed on graphite fiber surface in molten salts consists mainly of the Cr 7 C 3 phase. The Cr 7 C 3 -coating layer with plating time of 60 min and thickness of 0.5 lm was found to be most effective in improving the interfacial bonding and decreasing the interfacial thermal resistance between graphite fiber and aluminum matrix. The 40 vol% Cr 7 C 3 -coated graphite fiber/Al composite with Cr 7 C 3 thickness of 0.5 lm exhibited 45.4 % enhancement in inplane thermal conductivity of 221 W m -1 K -1 compared to that of uncoated composite, as well as the coefficient of thermal expansion of 9.4 9 10 -6 K -1 , which made it as very interesting material for thermal management applications.

Effect of Processing Conditions on Microstructure and Thermal Conductivity of Hot-Extruded Aluminum/Graphite Composites

“…Al/carbon fibers composites show unsatisfied TC values of 150220 W/mK, which is mainly attributed to the difficulties in orientation control of carbon fibers. 6) As is well known, graphite is highly anisotropic in both thermal and electrical conductivity, and the TC along its basal planes is much higher than that in c-axis. However, graphite is easy to react with liquid Al and form Al 4 C 3 phase, which can deteriorate the TC of Al/graphite composites.…”

Microstructure and thermal properties of nickel-coated carbon fibers/aluminum composites

“…In addition, the range of in the SPSed samples can be assumed as 60 À90 , thus cos 2 is calculated to be 0.083, which has been reported as a reasonable value. 5 To simply examine the thermal conducting mechanism at Al/Ni/C interfaces, we ignored the existence of Al 3 Ni phase at Ni/Al interfaces and assumed that CFs were coated by uniform pure Ni layer. In this case, K L and K T in equations ( 7) and ( 8) can be replaced by K eff L and K eff T , which mean CFs having an effective TC, given by…”

“…These carbon reinforced Al-matrix composites are widely used in thermal management fields due to their high thermal conductivity (TC), low coefficients of thermal expansion (CTE), and light weight. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] However, two key issues in carbon/Al systems are of great concern. (i) At relatively low processing temperatures, the bonding compatibility between Al and carbon is very weak, thus resulting in the formation of pores and other defects at carbon/Al interfaces.…”

“…(i) At relatively low processing temperatures, the bonding compatibility between Al and carbon is very weak, thus resulting in the formation of pores and other defects at carbon/Al interfaces. 5,6,11 (ii) At relatively high processing temperatures, Al is easier to react with carbon and form Al 4 C 3 compound, which is harmful for both thermal and mechanical properties of carbon/Al composites. [7][8][9] Therefore, to simultaneously enhance the bonding compatibility between Al and carbon as well as to avoid the formation of Al 4 C 3 phase, surface metallization of carbon materials is considered as one of the effective methods.…”

Effect of Carbon/Carbon Preform Density on the Microstructure and Properties of Mo2C Interlayer‐Modified Carbon/Carbon–Copper Composites for Sliding Contact Materials

“…It was suggested that the joint modified by Mo showed good adhesion, but exhibited lower shear strength compared with the joint modified by Cr. In the diamond–Cu composites, the interfacial bonding between Cu and Mo was also reportedly smaller than that between Cu and Ti or Cr because the solubility of Mo in copper is zero . Therefore, Mo 2 C was supposed to be a ideal modification interlayer with good wettability by copper, no solubility in copper, and a moderate bonding strength between carbon and copper.…”