A study of casting characteristics of some Nigerian clay slips for industrial production
Edoziuno FO, Iloghalu FI, Akaeze MC, Umeohia NO, Nwaeju CC, Anene FA
Laboratory Clay castability test has been conducted on three Nigerian clay samples: kankara clay, Barkimladi clay and Nsu clay; to determine their slip casting characteristics. Four specimens labeled K (kankara clay slip), B (Barkimladi clay slip), K + N (kankara clay blended with Nsu clay slip) and B + N (Barkimladi clay blended with Nsu clay slip) were prepared, mixed with water and deflocculated with Na2SiO3 to form casting slips. Plaster of Paris (P.O.P.) moulds were used to absorb the clay slips during slip casting, and the volume of the casting slip sucked-up was determined for each specimen at time intervals ranging from 0 to 35mins. The results obtained indicate that the volume of slip absorbed by the P.O.P. mould is proportional to the time of absorption. Graphs of volume of slip sucked-up against time were plotted and parabolic curves typical of clay casting were obtained. When volume of slip sucked-up were plotted against square root of time, linear curves were obtained, the gradient of which showed the rate of casting. Analysis of the experiment revealed that a better casting tendency of 9.3ml/mins was obtained for specimen B closely followed by specimen K + N at 10.7ml/mins. By contrast specimens K and B + N did not cast well and appropriate suggestions were given in order to improve their properties for use as casting slips.