Effects of particle size of Al(OH)₃ on the properties of porous purging materials

Abstract

Porous purging plug is promising in the course of steel-making especially for producing the pure steel. Five designed castables containing the same aggregates and different matrixes were fabricated successfully. Air permeability tests, microstructural characterization and grey incidence analysis were carried out to analyze the particle size of aluminum hydroxide [Al(OH) 3 ] effects on the properties of porous purging materials. According to the attained results, the smaller particle size of Al(OH) 3 seemed to be suitable to improve the properties of such materials, as it induced the formation of connected pores and hot modulus of rupture changed slightly. When the particle size was 36.1¯m, the air permeability could reach 13.4¯m 2 . Moreover, the grey incidence analysis matched to the experimental observations, attesting the smaller particle sizes (1020¯m) were helpful for enhancing the air permeability while the bigger particle sizes (²100¯m) had the opposite effects.

Effects of Aggregate Content on the Interconnected Pore Formation and Properties of Porous Purging Plug Materials

“…After thermal treatment, the apparent porosity and air permeability have the same tendency to change, that is, gradually increase. In addition, the shrinkage difference between aggregates and matrix can also form pores [12] and may contribute to the pore connectivity. With the increase of temperature, the shrinkage difference is even more pronounced, resulting in an increase in the number of interconnected pores, which is beneficial to the improvement of air permeability; moreover, with the increase of temperature, the structure becomes denser and the number of pores decreases, leading to a decrease of apparent porosity.…”

“…The increase in apparent porosity and the corresponding decrease in bulk density was attributed to the introduction of Al(OH) 3 . The Al(OH) 3 in the specimens can form a large amount of pores [12] after thermal treatment. Higher temperature facilitated the sintering process and made the structure Figure 1.…”

“…The method of incorporation of pore-forming agents with ceramic powder results can yield a porous structure of closed or poorly interconnected pores. Considerable research work directed at interconnected pore formation has been performed in our group [11][12][13][14]. The formation of interconnected pores is affected not only by the aggregate size [11] and content, but also by the pore-forming agent size [12] and content.…”

“…Considerable research work directed at interconnected pore formation has been performed in our group [11][12][13][14]. The formation of interconnected pores is affected not only by the aggregate size [11] and content, but also by the pore-forming agent size [12] and content. Larger aggregates facilitated pore linkage, which is beneficial to the formation of interconnected pores [11].…”

“…Point contact between aggregates is favorable for the formation and connectivity of the pores (Figure 1). A smaller particle size of Al(OH) 3 was suitable to induce the formation of interconnected pores [12] and a higher Al(OH) 3 content is beneficial to the pore formation after high-temperature treatment.…”