Ceramic filters for bulk inoculation of nickel alloy castings

The work includes the results of research on production technology of ceramic filters which, besides the traditional filtering function, play also the role of an inoculant modifying the macrostructure of cast nickel alloys. To play this additional role, filters should demonstrate sufficient compression strength and ensure proper flow rate of liquid alloy. The role of an inoculant is played by cobalt aluminate introduced to the composition of external coating in an amount from 5 to 10 wt.%. The required compression strength (over 1MPa) is provided by the supporting layers, deposited on the preform, which is a polyurethane foam. Based on a two-level fractional experiment 2^4-1, the significance of an impact of various technological parameters (independent variables) on selected functional parameters of the ready filters was determined. Important effect of the number of the supporting layers and sintering temperature of filters after evaporation of polyurethane foam was stated.