RHEOLOGY OF TRICALCIUM PHOSPHATE (β-TCP) SUSPENSIONS

958 Maria Spătaru et al.140120TCP-2fit CrossTCP-1fit Cross100τ [Pa]8060TCP-3fit Cross402000 100 200 300 400 500 600γ [1/s]Fig. 4 – The flow behaviour for the beta-tricalcium phosphate suspensions.2000175015001250η [mPa s]10007505002500TCP-2fit Cross TCP-1fit Cross0 100 200 300 400 500 600γ [1/s]TCP-3fit CrossFig. 5 – Viscosity curves for the beta-tricalcium phosphate suspensions.The preliminary results are promising as far asbeta–TCP powder preparation as aqueoussuspensions in view to casting mould is concerned.Also, the used additives for dispersing/stabilizingsuspensions carried out their role, although theywere not reported in the literature. As aconsequence of this preliminary study, it can beconcluded that the investigations related to thesuspensions of beta-TCP with the studied additivescould be continued.EXPERIMENTALBeta-tricalcium phosphate obtained from raw materials ofadvanced grade like NH 4 H 2 PO 4 and CaCO 3 , respectively,(Merck quality) was used in the experiments. The tricalciumphosphate has been prepared through the classic sintering insolid phase according to the reaction:2NH 4 H 2 PO 4 + 3CaCO 3 → Ca 3 (PO 4 ) 2 + 2NH 3 + 3CO 2 + 3H 2 O (2)The raw materials dosed to the compound stoichiometry the formation of the tricalcium phosphate (TCP) begins, andwere wet homogenized, in planetary mills, ethanol medium. then it was sintered at 1150 °C / 2 hours to finish theThe dried material was calcinated at 900 °C for 2 hours, when formation of the stoichiometric beta-TCP compound. The