Role of Al4C3 on the stability of the thermal conductivity of Al/diamond composites subjected to constant or oscillating temperature in a humid environment

Abstract

Present technologies allow fabrication of aluminum/diamond particles composites with excellent thermal properties, in particular showing the by far highest Thermal Conductivity of any of the materials being evaluated for thermal management. Although there is a widespread consensus concerning the essential role that the interface plays, it is not yet fully clear how the aluminum carbide formed at the interface affects thermal properties. In particular, how it affects the stability of the thermal properties of composites subjected to thermal treatments under wetting conditions. This is precisely the objective of the present work. To this end, samples were fabricated by means of gas pressure infiltration of liquid Al into preforms of packed diamond particles. Infiltration was carried out at two temperatures and three contact times. Thermal fatigue with cooling phase in water and performance in moisture environments at temperatures close to 100°C were evaluated. The results show that those samples having low amounts of carbide at the interface (shorter contact times) are more prone to a decrease of the thermal conductivity.

Aluminum carbide hydrolysis induced degradation of thermal conductivity and tensile strength in diamond/aluminum composite

“…Another research by Monje et al. 18 shows that the thermal conductivity remains almost unchanged after the diamond/Al composite samples are kept in a water vapor environment for 500 h. One possible explanation could be that the water diffusion into the sample is much slower in the form of vapor than liquid.

Figure 3.Change in thermal conductivity of the diamond/Al composite with soaking time.

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“…18 have investigated the thermal conductivity decrease of a diamond/Al composite having low amounts of carbide at the interface in a moisture environment at different temperatures, and they obtained the temperature-dependent rate constant of 0.007 and 0.010 for 70℃ and 90℃, respectively. It is noted that the time scale of the TC-t curve is hour in Monje et al., 18 and it is day in this study. If the time scale in Figure 3 is changed from day to hour, the temperature-dependent rate constant is varied from 0.050 to 0.002.…”

“…Nevertheless, the decrease of thermal conductivity is attributed to hydrogen diffusion by the investigators. 18…”

“…It has been reported that the hydration of Al 4 C 3 in the diamond/Al composite could occur in humid environment, 5,17,18 in de-ionized water, 19 and in alkaline solution. 20 Usually, the concentration of the methane (CH 4 ) gas released by the Al 4 C 3 hydration is measured to study the hydration of Al 4 C 3 .…”

Corrosion Behavior of Pressure Infiltration Diamond/Cu Composites in Neutral Salt Spray

“…Interfacial reaction products, impurities, defects, etc., all affect the corrosion resistance of the composites. The corrosion behavior of MMCs is also affected by the formation of interfacial products in the process of fabrication [11,12]. Due At any position in the salt spray box, a funnel with an area of 80 cm 2 could collect 1.5 to 1.6 mL solution per hour.…”