2.3.2. Diamond/Al
Chemical reaction is involved in diamond-Al system. Prolonged exposure of diamond to Al melt easily causes the excessive formation of undesired Al4C3. Great thermal resistance and heat damage of diamond make the TC much lower than the theoretical value [24].
In order to improve the interfacial bonding and suppress the formation of Al4C3, Si is added to Al alloy. Improved bonding is approved by the formation of SiC at the interface and the resulting TC is 375 W/(m·K). With respect to the diamond/Al composites produced by pressure infiltration, diamond particles are coated with SiC with the intention to restrict the undesirable interfacial reaction, but the TC is only 259 W/(m·K) due to the high interfacial resistance [25]. Ti-Coated diamond by vacuum slow vapor deposition method can reduce the thermal resistance significantly and improve the TC from 125 to 486 W/(m·K) [26]. It is noted that the formation of Al4C3 is beneficial to the enhancement of TC to a certain degree. For the composites fabricated by infiltration of Al alloy into porous diamond preform, the highest TC reaches 670 W/(m·K).