Novel Separation Technique of Particle Reinforced Metal Matrix Composites by Fused Deposition Method

Abstract

Abstract. To develop a novel separation technique of matrix alloys from metal matrix composite, separation experiments for various kinds of particle reinforced metal matrix composites (PRMMCs) were carried out. The Al-4mass%Cu alloy, Al-7mass%Si alloy and cast iron were used as matrix. The SiC particles (particle size: 75µm) and Al 2 O 3 particles (particle size: 120µm) were used as reinforcement. The PRMMC specimen was placed in a silica tube container with a small nozzle (nozzle size: 0.75mm) at the bottom and was melted by H.F. induction heating. Then the molten PRMMC specimen was forced to flow out through the nozzle by applying a certain pressure of Ar gas. Most of the molten matrix alloy flowed out through the nozzle and the remainder in the container consisted of the reinforcements and a part of the matrix alloy. The amount of separated matrix alloy increased with decreasing the volume fraction of reinforcement particles in PRMMC specimens. With decreasing the fabrication temperature from 1273K to 1073K, the amount of matrix alloy separated from SiC P /Al-7mass%Si alloy composites increased. It is considered that a reaction layer formed on the surface of SiC particles at 1273K improves the wettability between the molten matrix alloy and SiC particle, which prevents the separation of molten matrix alloy from reinforcements. On the other hand, the amount of separated matrix alloy from 20vol% Al 2 O 3P /cast iron composites was very high due to no reaction layer formed at interface between Al 2 O 3

Separation of PRMMC into matrix alloy and reinforcements by nozzle filtering method

“…The separation experiments using the container with various nozzle shapes 6 were carried out. The effect of applied pressure on nozzle filtering method has been reported by Mizumoto et al (2007) and the applied pressure in this work was 0.25 MPa.…”

“…In order 4 to investigate the effect of reactivity of the container material with the molten matrix alloy on the separation process, the containers were made of silica which was reactive to the molten aluminum alloy, or KC carbon ceramic which was unreactive. Mizumoto et al (2007) have reported an optimum nozzle size for nozzle filtering method and the nozzle size was 0.75mm in diameter. The PRMMC specimen was remelted at 1273K by H.F induction heating when silica tube was used as the container material.…”

“…However, the efficiency of these separation techniques is not satisfactory. In our earlier works, the present authors have found that most of matrix alloy was separated from PRMMCs in the experiments of fused spinning deposition process (FSD process) (Oishi et al, 2004;Oishi et al, 2004Mizumoto et al, 2007) and have termed this separation method "nozzle filtering method". In this work, to establish the nozzle filtering method as the recycling process for MMCs, the optimum separation conditions and the effect of the separation process on the separated matrix alloy and reinforcements were investigated.…”