scholarly journals Powder bed selective laser process (sintering/melting) applied to tailored calcium phosphate-based powders

2021 ◽  
Author(s):  
Pedro Navarrete-Segado ◽  
Christine Frances ◽  
Mallorie Tourbin ◽  
Christophe Tenailleau ◽  
Benjamin Duployer ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Calcium Phosphate ◽  
Calcium Phosphates ◽  
Process Window ◽  
X Ray Diffraction ◽  
Powder Bed ◽  
Laser Process ◽  
Whole Process ◽  
Vibrational Spectroscopies ◽  
Complex Parts

This paper focuses on the tailoring of calcium phosphate powders for their use as powder bed selective laser process feedstock. Hydroxyapatite and chlorapatite were used as starting powders for the preparation of different blends through the addition of graphite as a laser absorptance additive. A methodical study was conducted to compare the processing windows of the blends containing different amounts of graphite through the laser patterning of circular samples. It was found that the addition of graphite increases the process window of the powder blends being the powder without additive non processable. Hydroxyapatite showed a clear phase transition (decreased when using higher volumetric energy density) into other calcium phosphate phases while chlorapatite was demonstrated to be thermally stable during the whole process (examined through X-ray diffraction and vibrational spectroscopies). In parallel, the study evaluating the powder blend composed of hydroxyapatite and graphite for the production of solid and complex parts was carried out although it required long printing times. The productivity of the process was improved by modification of printing parameters. Then, a series of solid samples were produced for the analysis of the microstructure and mechanical properties. High interconnected porosity was observed in the samples which could improve the bioactivity of the bioceramic scaffolds. A post-treatment of the parts increased their proportion in the hydroxyapatite phase and their mechanical properties. These results are expected to contribute to the application of powder bed selective laser processing of calcium phosphates powders toward bone tissue engineering.

Synthesis of Alpha-Tricalcium Phosphate by Wet Reaction and Evaluation of Mechanical Properties

2012 ◽  
Vol 727-728 ◽  
pp. 1164-1169 ◽  
Author(s):  
Mônica Beatriz Thürmer ◽  
Rafaela Silveira Vieira ◽  
Juliana Machado Fernandes ◽  
Wilbur Trajano Guerin Coelho ◽  
Luis Alberto Santos
Keyword(s):  
Mechanical Properties ◽  
Calcium Phosphate ◽  
Tricalcium Phosphate ◽  
Calcium Nitrate ◽  
Chemical Precipitation ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Calcium Phosphate Cements

Calcium phosphate cements have bioactivity and osteoconductivity and can be molded and replace portions of bone tissue. The aim of this work was to study the obtainment of α-tricalcium phosphate, the main phase of calcium phosphate cement, by wet reaction from calcium nitrate and phosphoric acid. There are no reports about α-tricalcium phosphate obtained by this method. Two routes of chemical precipitation were evaluated and the use of two calcinations temperatures to obtain the phase of cement. The influence of calcination temperature on the mechanical properties of cement was evaluated. Cement samples were characterized by particle size analysis, X-ray diffraction, mechanical strength and scanning electron microscopy. The results demonstrate the strong influence of synthesis route on the crystalline phases of cement and the influence of concentration of reactants on the product of the reaction, as well as, on the mechanical properties of cement.

scholarly journals Effect of Saturation and Post Processing on 3D Printed Calcium Phosphate Scaffolds

2008 ◽  
Vol 396-398 ◽  
pp. 663-666 ◽  
Author(s):  
Tamas D. Szucs ◽  
Dermot Brabazon
Keyword(s):  
Mechanical Properties ◽  
Calcium Phosphate ◽  
Sodium Phosphate ◽  
Three Dimensional ◽  
Surface Topology ◽  
Phosphate Solution ◽  
X Ray Diffraction ◽  
Three Dimensional Printing ◽  
Sodium Phosphate Solution ◽  
3D Printed

Three dimensional printing was investigated for fabricating hydroxyapatite (HA) and β-tricalcium phosphate (β-TCP) composite scaffolds using calcium phosphate based ceramics and calcium phosphate cement chemistry. Scaffolds were formed by printing an aqueous sodium phosphate solution on the powder bed consisting of a mixture of dicalcium phosphate anhydrous (DCPA) and calcium hydroxide powders. The sodium phosphate solution was functioning as a binder material and also as the initiator of the wet chemical reaction. Compressive mechanical properties of printed samples were examined as a function of saturation level that was inversely proportional to the powder to liquid ratio. To increase mechanical properties and obtain hydroxyapatite and β-TCP composites, the printed samples were sintered. The effect of sintering parameters including dwell time and sintering temperature were also examined. X-ray diffraction (XRD) was used to examine material composition at different stages of the manufacturing process and to confirm the presence of HA and β-TCP in the final stage. The effect of sintering procedure on the surface topology of the samples was examined using scanning electron microscopy (SEM).

Carboxymethylchitosan/Calcium Phosphate Hybrid Materials Prepared by an Innovative Auto-Catalytic Co-Precipitation Method

2005 ◽  
Vol 284-286 ◽  
pp. 701-704 ◽  
Author(s):  
S.A. Costa ◽  
J. Miguel Oliveira ◽  
Isabel B. Leonor ◽  
Rui L. Reis
Keyword(s):  
Calcium Phosphate ◽  
Calcium Phosphates ◽  
Precipitation Method ◽  
Porous Scaffolds ◽  
X Ray Diffraction ◽  
Polymer Precipitation ◽  
Acid Bath ◽  
The Fourier Transform ◽  
Xrd Patterns ◽  
Co Precipitation

In this study, it is shown that it is possible to prepare carboxymethyl-chitosan/Ca-P hybrids using an innovative “auto-catalytic” co-precipitation method, namely by using an acid and an oxidant bath. The X-ray diffraction (XRD) patterns evidenced the formation of crystalline calcium-phosphate precipitates when using an acid bath, while amorphous ones were obtained for those produced in the oxidant bath. The Fourier Transform Infrared spectroscopy (FTIR) and Scanning Electron Microscopy (SEM/EDS) studies revealed that the extent of the polymer precipitation and formation of calcium-phosphates is directly dependent on the pH and composition of the baths. Furthermore, by conducting bioactivity tests in a simulated body fluid (SBF) followed by the SEM/EDS analysis it was possible to detect the formation of an apatite layer with a cauliflower-like morphology on the surface of hybrids prepared by the acid bath, after 7 days of immersion. These results are quite promising because they can allow for the production of bioactive and biodegradable 3D porous scaffolds to be used in bone tissue engineering applications.

scholarly journals Powder bed selective laser process (sintering/melting) applied to tailored calcium phosphate-based powders

2021 ◽  
pp. 102542
Author(s):  
P. Navarrete-Segado ◽  
C. Frances ◽  
M. Tourbin ◽  
C. Tenailleau ◽  
B. Duployer ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Powder Bed ◽  
Laser Process

scholarly journals Influence of Local Porosity on the Mechanical Properties of Direct Metal Laser-Sintered 1.2709 Alloy

2020 ◽  
Vol 66 (6) ◽  
pp. 351-357
Author(s):  
István Hatos ◽  
Imre Fekete ◽  
Dóra Harangozó ◽  
Hajnalka Hargitai
Keyword(s):  
Mechanical Properties ◽  
Tool Steel ◽  
Steel Powder ◽  
Great Flexibility ◽  
Powder Bed ◽  
Metal Printing ◽  
Local Porosity ◽  
Technological Limitations ◽  
Complex Parts

Powder bed metal printing has demonstrated its potential for the direct manufacturing of complex parts. It has great flexibility compared to conventional manufacturing. There are also some difficulties and problems, e.g., because the process stops during production. When the process is restarted, the first layer may be thicker due to technological limitations. In this paper, the effects caused by the presence of these thicker layers were investigated. The possibility of re-melting the layers to reduce porosity were also analysed. A tool steel powder grade 1.2709 was used to produce samples with an increased thickness of melted layers.

scholarly journals Integrated 3D Information for Custom-Made Bone Grafts: Focus on Biphasic Calcium Phosphate Bone Substitute Biomaterials

2020 ◽  
Vol 17 (14) ◽  
pp. 4931
Author(s):  
Alessandra Giuliani ◽  
Maria Laura Gatto ◽  
Luigi Gobbi ◽  
Francesco Guido Mangano ◽  
Carlo Mangano
Keyword(s):  
Calcium Phosphate ◽  
Biphasic Calcium Phosphate ◽  
Alveolar Bone ◽  
Sintering Temperature ◽  
Calcium Phosphates ◽  
Compressive Loading ◽  
Peak Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Custom Made

Purpose: Several studies showed that the sintering temperature of 1250 °C could affect the formation of α-Ca3(PO4)2, which is responsible for the reduction of the hardness value of biphasic calcium phosphate biocomposites, but they did not evaluate the inference of the sintering time at peak temperature on transition of β-Ca3(PO4)2 to α-Ca3(PO4)2. This analysis explored, in an innovative way, inferences and correlations between volumetric microstructure, mechanical properties, sintering temperature, and time at peak temperature in order to find the best sintering conditions for biphasic calcium phosphate composites grafted in severe alveolar bone defects. Methods: Sintered biphasic calcium phosphates (30%-hydroxyapatite/70%-tricalcium phosphate) were tested by microCT imaging for the 3D morphometric analysis, by compressive loading to find their mechanical parameters, and by X-ray diffraction to quantify the phases via Rietveld refinement for different sintering temperatures and times at the peak temperature. Data were analysed in terms of statistical inference using Pearson’s correlation coefficients. Results: All the studied scaffolds closely mimicked the alveolar organization of the jawbone, independently on the sintering temperatures and times; however, mechanical testing revealed that the group with peak temperature, which lasted for 2 hours at 1250 °C, showed the highest strength both at the ultimate point and at fracture point. Conclusion: The good mechanical performances of the group with peak temperature, which lasted for 2 hours at 1250 °C, is most likely due to the absence of the α-Ca3(PO4)2 phase, as revealed by X-ray diffraction. However, we detected its presence after sintering at the same peak temperature for longer times, showing the time-dependence, combined with the temperature-dependence, of the β-Ca3(PO4)2 to α-Ca3(PO4)2 transition.

Characterization of Calcium Phosphate with an Anodic TiO2 Nanotube Layer on Titanium Screw for Biomedical Application

2014 ◽  
Vol 852 ◽  
pp. 251-255
Author(s):  
Ya Jing Yan ◽  
Yong Huang ◽  
Qiong Qiong Ding ◽  
Xiao Feng Pang
Keyword(s):  
Calcium Phosphate ◽  
Biomedical Application ◽  
Calcium Phosphates ◽  
Alkaline Treatment ◽  
Calcium Phosphate Coating ◽  
X Ray Diffraction ◽  
Titanium Screw ◽  
Phosphate Coatings ◽  
Titanium Screws ◽  
Calcium Phosphate Coatings

The present paper reports a novel solution to develop a calcium phosphates (CaPs) coating with an anodic nanotubular TiO2layer on titanium screw by electrochemical disposition (ECD). The elemental composition of coatings was examined by energy dispersive spectroscopy (EDS), the surface mopholoy was characterized with scanning electron microscopy (SEM), and the functional groups and crystalline phase were analyzed using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Furthermore, the bioactivity was tested by immersion in simulated body fluid (SBF) for 7 days. The results showed that a nanotubular TiO2layer was established which has about 100 mm diameter and the calcium phosphate coatings have higher bioactivity and porosity compared with uncoated titanium screws, which make the coating more conductive to cell adhesion. Using alkaline treatment, the calcium phosphate coating could transform into hydroxyapatite (HAp), making the coating closer to the biological complement. This provides a valuable tool for biomedical applications.

Effects of citrate and NaCl on size, morphology, crystallinity and microstructure of calcium phosphates obtained from aqueous solutions at acidic or near-neutral pH

2012 ◽  
Vol 79 (2) ◽  
pp. 238-248 ◽  
Author(s):  
Omar Mekmene ◽  
Thierry Rouillon ◽  
Sophie Quillard ◽  
Paul Pilet ◽  
Jean-Michel Bouler ◽  
...  
Keyword(s):  
Calcium Phosphate ◽  
Calcium Phosphates ◽  
Octacalcium Phosphate ◽  
Inhibitory Effect ◽  
Particle Sizes ◽  
X Ray Diffraction ◽  
Phosphate Dihydrate ◽  
Constant Ph ◽  
Starting Solutions ◽  
Calcium Phosphate Precipitation

Precipitation of calcium phosphates occurs in dairy products and depending on pH and ionic environment, several salts with different crystallinity can form. The present study aimed to investigate the effects of NaCl and citrate on the characteristics of precipitates obtained from model solutions of calcium phosphate at pH 6·70 maintained constant or left to drift. The ion speciation calculations showed that all the starting solutions were supersaturated with respect to dicalcium phosphate dihydrate (DCPD), octacalcium phosphate (OCP) and hydroxyapatite (HAP) in the order HAP>OCP>DCPD. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) analyses of the precipitates showed that DCPD was formed at drifting pH (acidic final pH) whereas poor crystallised calcium deficient apatite was mainly formed at constant pH (6·70). Laser light scattering measurements and electron microscopy observations showed that citrate had a pronounced inhibitory effect on the crystallisation of calcium phosphates both at drifting and constant pH. This resulted in the decrease of the particle sizes and the modification of the morphology and the microstructure of the precipitates. The inhibitory effect of citrate mainly acted by the adsorption of the citrate molecules onto the surfaces of newly formed nuclei of calcium phosphate, thereby changing the morphology of the growing particles. These findings are relevant for the understanding of calcium phosphate precipitation from dairy byproducts that contain large amounts of NaCl and citrate.

scholarly journals Calcium phosphate crystal forms in human jaw bones of changed osteoporotic structure

2011 ◽  
Vol 58 (1) ◽  
pp. 23-28
Author(s):  
Srdjan Postic
Keyword(s):  
Calcium Phosphate ◽  
Calcium Phosphates ◽  
Chemical Compounds ◽  
Osteoporotic Bone ◽  
X Ray Diffraction ◽  
Crystal Forms ◽  
Jaw Bone ◽  
Jaw Bones ◽  
Human Cadavers ◽  
Hydrated Calcium

Introduction. Calcium phosphates are chemical compounds that can be found in various forms within nature, as well as in human jaws and bones. The aim of this study was to assess the structure of solid chemical compounds which form the structure of normal and osteoporotic jaw-bones. Materials and Methods. The jaw-bones taken from human cadavers were used in the study. Crystalographic forms of calcium phosphate, in the samples of human jaw-bone, were determined using X-ray diffraction technique. The experimental bone samples originated from osteoporotic jaw-bone of cadavers while control samples were taken from dentate jaw-bones of non-osteoporotic cadavers. Results. The results of this study showed that hydroxyapatite was the only phase determined in control non-osteoporotic bone samples. In experimental (osteoporotic) bone samples, the same phase was registered, as well as calcium monophosphate and hydrated calcium phosphate, registered as increments of values on ? axis. Conclusion. Hydroxyapatite was the only compound detected in normal bone while osteoporotic bone contained others crystallographic forms of calcium phosphates.

Sign in / Sign up

Export Citation Format

Share Document