Efficient separation of reinforcements and matrix alloy from aluminum matrix composites by supergravity technology

Abstract A supergravity-induced separation method was proposed to recover matrix alloy and SiC particles from scrap aluminum matrix composites (AMCs). Effects of the gravity coefficient (G), temperature (T), and separation time (t) on the separation efficiencies were evaluated and the corresponding separation mechanism was analyzed. Under optimum conditions (T = 710 °C, G = 600, and t = 300 s), the recovery rates of Al and SiC reached 83.9 and 98.2%, respectively. The theoretical calculated separating efficiencies based on the capillary law were in good consistent with the observed values. At 710 °C, the interfacial reaction between liquid Al and SiC that produced Al4C3 and free Si was limited. A small amount of Al4C3 was retained in the residue. After removing Al4C3 and excess metallic Al from the residue by acid pickling, the SiC particles were thoroughly recovered and could be directly reused as fresh reinforcements. Moreover, an amplified centrifugal separation apparatus was conceptually designed for recycling AMC scraps on an engineering scale. Preliminary results indicate that supergravity technology can be potentially employed as a practical process for recovering reinforcements and matrix alloy from scrap AMCs.