TY - JOUR A1 - Dombrowski, Felix A1 - Hoffmann, Rita A1 - Ploska, Ute A1 - Marx, Heidi A1 - Berger, Georg T1 - Investigations on degradable and figuline calcium alkaline phosphate cements with multimodal particle size distribution N2 - The paper presented here deals with rheological and hardening properties during the setting reaction, and density and compressive strength after the final setting of a figuline composite consisting of Ca2KNa(PO4)2 and 2wt% medium gel strength gelatin. Compared to the composite with monomodal particle size distribution (d50=7.18µm; span=3.9) and its properties during and after setting reaction, the goal of this work is to increase the resulting product compressive strength by mixing different particle sizes in order to obtain bi- and trimodal distributions. For the bimodal powder mixtures the ratio in diameter (dcourse/dsmall) was chosen with 7/1 and volume ratio dcourse/dsmall was 70/30%. For the trimodal powder mixtures the ratio in diameter (dcourse/dmedium/dsmall) was chosen with 70/7/1 and volume ratio dcourse/dmedium/dsmall was set to 44/28/28%.After establishing an adequate crushing and sieving process the tap density and powder density of each fraction was determined. Subsequently, the different particle sizes were mixed and the densities and the Hausner ratio were determined again. The mixtures show an increase in both densities especially the tap density increased significantly. Rheological investigations show that the graphs of storage and loss moduli of the multimodal powder mixtures respectively are similar. The characteristic setting times show a slight decrease compared with the monomodal composite but not significantly different data. When comparing the resulting compressive strength of cylindrical samples, which were stored direct after reaching the initial setting time under physiological conditions, the studies illustrated in all cases for the multimodal mixtures a significant increase in compressive strength and a higher density. KW - Calcium alkaline phosphate cement KW - Gelatin KW - Compressive strength KW - Figuline KW - Particle size PY - 2012 DO - https://doi.org/10.4028/www.scientific.net/KEM.493-494.355 SN - 1013-9826 VL - 493-494 SP - 355 EP - 360 PB - Trans Tech Publ. CY - Aedermannsdorf AN - OPUS4-24925 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dombrowski, Felix A1 - Garcia Caso, P.W. A1 - Laschke, M.W. A1 - Klein, M. A1 - Günster, Jens A1 - Berger, Georg T1 - 3-D printed bioactive bone replacement scaffolds of alkaline substituted ortho-phosphates containing meta- and di-phosphates N2 - The paper presented here deals with the investigations of orthophosphates (Q0) containing none or differing amounts of meta-(Q2) and diphosphate phases (Q1) for the use of 3-dimensional printing process in order to create porous, bioactive, nonloadbearing bone replacement scaffolds. The main ceramic phase in all cases is Ca10[K/Na](PO4)7 hereinafter called 401545(100) consisting of 99,9% Q0 and 0,1% Q1-phase. The other phosphate ceramics i) 401545(40) consists of 75% Q0-phase, 22% Q1-phase and 4% Q2-phase ii) 401545(15) consists of 65% Q0-phase, 33% Q1-phase and 2% Q2-phase iii) 401545consists of 56% Q0-phase, 40% Q1-phase and 4% Q2-phase. The in-house produced ceramics where crushed and sieved to achieve particles of irregular shape in the range of 45-90µm. These powders show a quite good flowability and were used to generate cylindrical samples with a diameter of 5,5mm and a height of 11mm via 3-dimensional printing using a R1 printer from ProMetal company (USA). After drying the samples at T=125°C for 48 hours they were sintered at temperatures according to the thermal analysis results in the range of 900°C up to 1300°C. Afterwards the porosity, the linear shrinkage and the compressive strength were determined. KW - Calcium alkaline phosphates KW - 3-D printing KW - Porosity KW - Compressive strength PY - 2013 DO - https://doi.org/10.4028/www.scientific.net/KEM.529-530.138 SN - 1013-9826 VL - 529-530 SP - 138 EP - 142 PB - Trans Tech Publ. CY - Aedermannsdorf AN - OPUS4-26972 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -