Reaction And Solid-state Sintering Behavior Of Calcium Polyphosphate/Calcium Sulfate Composite Bioceramics

Calcium polyphosphate(CPP)/ calcium sulfate(CaSO₄) bioceramics were preparedby solid-state sintering method. The phase composition of composite bioceramicssintered at different temperatures was analized by X-ray powder diffraction (XRD);the sintering behavior of composite was investigated by bulk density, apparentporosity and linear shrinkage. The effects of CaSO₄ dosage and sintering temperatureon the sintering behavior of composite bioceramics were also studied. Themicrostructure of composite after sintering and soaking in the SBF solution wasinvestigated by Scanning Electron Microscopy. The results showed that biphasiccomposition ofβ-CPP/CaSO₄ could be obtained through combining ACPP withCaSO₄ at low temperatures, such as 600℃, but when sintered at high temperatures,solid-state reaction would occur. BCPP composites showed a similar tendency ofphase composition when temperatures varied, but had lower densification than ACPPcomposites.In order to realize densification at low temperatures, vacuum-sintering andhot-pressed sintering methods were used, and their sintering behavior was comparedwith samples prepared through pressureless sintering. The results showed thatcomposite bioceramics prepared by vacuum sintering had worse sintering properties,while displaced the as-expected phase composition and showed better sinteringproperties by hot-pressed sintering .ACPP/calcium sulfate composite bioceramics were soaked in SBF solution forin-vitro dynamic degradation experiments. The weight loss and microstructure afterdegradation were studied, the results showed that dynamic degradation process wasbetter for the degradation of composite bioceramics.