Determination of stability of ceramics suspension by means of sedimentation test

U ovom radu prikazan je utjecaj pojedinih disperzanata na stabilnost keramičke suspenzije koja se koristi za oblikovanje keramičkih proizvoda postupkom lijevanja iste. Pripravljene su 20 %-tne Al 2 O 3 vodene suspenzije stabilizirane s četiri različita disperzanta, pri različitim pH vrijednostima u rasponu od cca 2 do cca 11. Korišteni su sljedeći disperzanti: • Natrijeva sol sulfonske kiseline (Tiron, 0,1 %) • Limunska kiselina (0,1 %) • Amonij polimetakrilat (Darvan C-N, 0,6 %) • Polielektrolit na bazi karbonske kiseline (Dolapix CE-64, 0,2 %). Ispitan je utjecaj pH vrijednosti na stabilnost priređenih 20 %-tnih Al2O3 vodenih suspenzija stabiliziranih s navedenim disperzanatima. Stabilnost suspenzija određena je sedimentacijskom testovima mjerenjem volumena sedimenta u vremenskim intervalima od 15 min, 1 sat, 2 sata, 24 sata, 48 sati, 72 sata, 96 sati i 168 sati. Dobiveni rezultati pokazuju da na stabilnost 20 %-tne Al2O3 vodene suspenzije utječe vrsta disperzanta, pH vrijednost suspenzije i vrijeme sedimentacije.This thesis shows the influence of certain dispersants on stability of ceramic suspension, which is used for shaping ceramic products using slip casting method. Al2O3 aqueous suspensions with solid loading of 20 wt. % stabilized with different dispersants were prepared at different pH values ranging from about 2 to about 11. Following dispersants were used: • 4,5-dihydroxy-1,3-benzenedisulfonic acid disodium salt monohydrate (Tiron, 0,1 % of dry matter mass) • Citric acid monohydrate (0,1 % of dry matter mass) • Ammonium polymetacrylate (Darvan C-N, 0,6 % of dry matter mass) • Carbonic acid based polyelectrolyte (Dolapix CE-64, 0,2 % of dry matter mass) Influence of pH values on stability of prepared Al2O3 aqueous suspensions (with solid loading of 20 wt. % and dispersants) was tested. Stability of suspension is determined by sedimentation tests in which volume of sediment was measured at different time intervals: 15 minutes, 1 hour, 2 hours, 24 hours, 48 hours, 72 hours, 96 hours and 168 hours. The results show that stability of Al2O3 aqueous suspension (with solid loading of 20 wt. %) is influenced by type of dispersant used, pH value of suspension and sedimentation time