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

Diamond particles reinforced aluminum matrix (diamond/Al) composite is receiving great interests as a thermal management material due to its superior thermal conductivity and light weight. The diamond/Al composite is, however, incurring a problem of aluminum carbide (Al₄C₃) hydrolysis in the applications. Here we propose an accelerated hydrolytic ageing method to assess the reliability of diamond/Al composite in water environment. The diamond/Al composite specimens have been immersed in distilled water at room temperature up to 115 days. The microstructural characterization shows that water diffuses into the composite and reacts with the interfacial Al₄C₃ phase to generate Al(OH)₃ and CH₄. The concentration of the collected methane gas was measured by using a gas chromatograph technique to monitor the hydrolysis reaction. With prolonging soaking time from 5 to 115 days, the normalized methane concentration increases from 4 × 10⁻⁴ to 2 × 10⁻³, the thermal conductivity decreases from 467 to 347 W/mK, and the tensile strength decreases from 105 to 61 MPa. The property degradation is ascribed to the hydrolysis of Al₄C₃, which is harmful to the structural integrity of the diamond/Al composite. The finding provides guideline for the protection of diamond/Al composite components in service environments.