Refractories Review: Refractories in Japan – 2002
The three main topics of the program were steelmaking (40%), fundamental research (23%) and monolithic refractories (21%). Other topics focused on refractories for the environment and other industries. The Wakabayashi Prize papers included “In-Situ X-Ray and Microstructure Analysis of Slag Penetration into MgO Refractories,” “Synthesis of Whisker-Like Spinel from Gibbsite and Mg Acetate,” “Compaction Characteristics for Powder by Uniaxial Pressing” and “Effect of Alumina-Zirconia Grain Microstructure on Thermal Spalling Resistance of Refractories.”
Colloquium HighlightsNumerous papers dealt with iron/steel flow control devices, including slide gates, nozzles, tubes, tundishes, troughs and taphole mixes. One paper dealt with the effect of alumina grain size and fused silica content in alumina-silica-30% carbon mixes. Mixes containing coarse and fine alumina, along with a lower silica content, had higher strength. Mixes with only coarse alumina had better thermal shock resistance with increased silica content (up to 30 wt%), due to the development of microcracks around the aggregate grains. The corrosion resistance was also better with coarse and fine alumina, although in all cases it decreased with increasing silica content.
Another paper described the development of a submerged nozzle with higher corrosion resistance. An improved material, which was localized on the nozzle surface and included secondary spinel and lower carbon content, had higher thermal expansion and better insulating character.
All of the Wakabayashi Prize-winning papers were fundamental studies. Other examples of fundamental papers included “Microwave Furnace for Sintering Ceramics;” “New, More Definitive Rotary Corrosion Testing Apparatus;” “Evaluation of the Labyrinth Factor for Porous Plugs;” and “Study of ZrO2-BN-TiC-TiB2 Composite.”
The topic of one monolithic refractory session was blast furnace taphole mixes, including densification, drillability and hardening behavior. Another monolithic refractory paper dealt with the relationship between properties and performance of the metal/slag line of a blast furnace trough castable. The best corrosion/wear results were realized by mutual optimization of the constituents (fused spinel, SiC and superfine alumina). Other monolithic refractory papers included “Abrasion Testing” and “Effect of Aggregate Porosity on Castable Properties.”