Yoon Suk Oh

Effect of Frit Content on the Metal Marking and Scratching Resistance of Celadon Glaze

Metal marking and scratching are related to surface roughness, hardness and toughness of glaze. To improve the glaze properties, frits were added in the traditional celadon glaze and reducing firing atmosphere was controlled. Surface roughness of celadon glaze was decreased with increasing the reducing agent content (LPG flowing rate) and increasing the frits content. Though hardness of glaze without frit was increased with increasing the reducing agent content, hardness of glaze with frit was not changed extremely with increasing the reducing agent content. To evaluate the metal marking and scratching resistance, wear resistance test was used with stainless steel ball. After wear test, many metal marks and wide scratching trace were observed in the traditional celadon glaze. However, a few metal mark and scratch were observed in the celadon glaze with frit. The friction coefficient of glaze in the wear test was strongly depended on the frit contents.

Synthesis of Zr-Based Glassy Alloy Foams

The present basically concerns with the synthesis of foamy structured amorphous Zrbased alloy, Zr41.2Ti13.8Cu12.5Ni10.0Be22.5 (Vit-1), by liquid state processing. In this method, melt was injected in to the evacuated interstitial voids of the NaCl crystals placed in a copper mould. The casting has been subsequently washed with a jet of water to ensure the removal of NaCl entrapped in the casting, thus resulting in a porous structured casting. It shows the possibility of synthesizing amorphous metal foams with large dimensions using salt infiltration technique.

Solidification Behavior of Fe-Base Amorphous Alloys during Twin-Roll Strip Casting

Solidification behavior of two Fe-base amorphous alloys during twin-roll strip casting has been investigated in the present study. Continuous cooling transformation (CCT) diagrams of both alloys were calculated using the heterogeneous nucleation theory coupled with thermal data obtained during cooling. Cooling sequence during twin-roll strip casting was also simulated. These were used for the determination of the optimum twin-roll strip casting conditions at which desirable solidification behavior could be achieved. It shows that twin-roll strip casting can continuously fabricate sheet product of Fe-base bulk amorphous alloys, despite their higher liquidus temperatures and larger differences between liquidus and glass transition temperatures (Tg) than those of other easier glass-forming bulk amorphous alloys.