Development of novel carbon bonded filter compositions for steel melt filtration

Carbon-bonded alumina filters for steel melt filtration are increasingly used by steel foundries. Their potential regarding material characteristics and filtration efficiency has not been fully exploited yet. A new filter composition based on the synthetic coal tar pitch Carbores® P, has been explored. Its compatibility with a water-based dispersing system allows additions of carbon black, graphite, and additives to reach a residual carbon content of up to 30 wt.%. For determining physical properties and variables of the respective compositions, 10 pores per inch (ppi) foam ceramic filters were manufactured via the Schwartzwalder process. The influence of different binder contents on the processing properties and mechanical characteristics of the system was evaluated. Based on these studies, an increase in cold crushing strength of approx. 30% has been achieved in comparison to current state of the art materials.