Fabrication of Al-Based FGM Containing TiO₂ Nano-Particles by a Centrifugal Mixed-Powder Method

Abstract

Centrifugal method is often applied as the fabrication process of Functionally Graded Materials (FGMs). This is because that this processing method can fabricate FGMs with large size, easily. However, this processing method has a serious problem, namely it is difficult to disperse particles with small size and low wet ability with matrix. Many of powders with nano or very fine particle size often have attractive attention as functional materials. Therefore the above problem of the centrifugal method should be improved. In this study, we proposed a centrifugal mixed-powder method as novel processing technique for the fabrication of FGM containing nano-particle. On first of this processing, powder mixture of functional nano-particle and matrix material is inserted into rotating mold. After that, matrix ingot is melted in crucible and then the molten matrix is poured into the rotating mold with powder mixture, and then, powder of matrix material will be melted by the heat from molten matrix poured from crucible. Finally, an FGM ring with functional nano-particles distributed on its surface can be obtained. Using this processing method, Al-based FGM containing TiO2 nano-particles on its surface could be fabricated. TiO2 particle has approximately 500nm in diameter. From microstructural observation, it was found that TiO2 particles were successfully distributed on surface of FGM ring. Also, hardness on the surface of the FGM ring was higher than that on inner part due to the dispersion hardening.

Fabrication of Al-Al3Ti/Ti3Al Functionally Graded Materials under a Centrifugal Force

“…As a more developed CM process, the centrifugal mixed-powder method (CMPM) was recently proposed by Watanabe et al . [ 19 , 20 ]. As a first step of the CMPM, a powder mixture of dispersion-particles, B , and matrix metal particles, A , is inserted into a spinning mold ( Figure 4 (a)).…”

Functionally graded materials classifications and development trends from industrial point of view

“…Powder metallurgy represents one of the important method of producing FGMs containing shape gradient [121]. Only cylindrical shapes can be formed [38,[100][101][102] Gravity settling Continuous Grading can be achieved using this method A range of particle sizes can be used Tendency to produce separate zones of relatively constant volume fraction. Not suitable for all materials [36] Additive manufacturing (AM) and solid freeform fabrication (SFF)…”

A Novel Fabrication Method for Functionally Graded Materials under Centrifugal Force: The Centrifugal Mixed-Powder Method

“…Since the photocatalytic TiO 2 particles are of nano-sized diameter, the motion of TiO 2 particles with different particle size in a molten Al under a centrifugal force is numerically modeled based on the Stokes’s law to study the effect of particle size on the compositional gradient. Figure 2 shows the effect of particle size on the compositional gradient in the Al/TiO 2 FGM fabricated by the centrifugal solid-particle method [ 16 ]. Volume fraction of TiO 2 and centrifugal force were fixed to be 10 vol % and G = 50, respectively.…”

“…Al/TiO 2 FGMs were fabricated by the centrifugal mixed-powder method using these powder mixtures. A horizontal-type centrifugal casting machine was conducted for this experiment [ 16 ]. The applied centrifugal force was G = 80.…”

“…Figures 13 (a), (b) and (c) show the SEM microstructure, Al and Ti distribution maps on outer surface of the Specimen A, respectively [ 16 ]. SEM microstructure, Al and Ti distribution maps on the outer surface of the Specimen B are shown in Figures 14 (a), (b) and (c), respectively.…”