Surface modification of titanium-based implants has been extensively researched as an effective tool to generate a bioactive surface that helps to create a new bone and forms a natural bond at the ...interface between the implants and surrounding bone tissues. The present research is focused on the development of a new methodology to obtain sphene (CaTiSiO5) biocoatings on titanium substrates. Based on previous results, where sphene coatings were obtained by a manual airbrush, the coating system was improved in order to have a full control of the process in terms of uniform morphology of the biocoating. The effectiveness of the coating system and deposition process is supported by microscopic analysis of the produced coatings, by surface roughness measurements of uncoated and coated substrates, and estimation of the adhesion strength between the coatings and the substrate. The results showed that the coatings had crack-free homogenous surfaces with ideal characteristics for orthopedic and dental implants in terms of adhesion strength and surface roughness.
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•An automatic spray coating system was developed in order to deposit sphene precursors on Ti substrates.•The deposition time effect on coating thickness and roughness was studied.•The developed sphene coating was characterized to be a layered and porous.•Even at high overall thickness the coatings was completely crack-free and showed a good adhesion strength to the substrate.
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Wollastonite-diopside scaffolds have been successfully developed by direct ink writing of an ink made of silicone polymer and inorganic fillers. The main reason for using a silicone in the ink ...formulation consisted in its double effect, in controlling the ink rheology and in developing of wollastonite and diopside crystalline phases upon heat treatment. The obtained 3D wollastonite-diopside scaffolds featured regular geometries, and a high compressive strength (3.9–4.9MPa) when considering the large amount of porosity (68–76 vol.%). A glass with the same oxide composition as the silicone-based ink and crystallizing into wollastonite and diopside, was produced and used as additional filler. This addition enabled the fabrication of even stronger 3D printed scaffolds (∼8MPa for a porosity of 67 vol%), owing to the enhanced viscous flow upon firing which reduced the micro-cracks in the scaffold struts generated by the preceramic polymer decomposition. The obtained highly porous wollastonite-diopside glass-ceramic scaffolds are suitable candidates for bone tissue engineering.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Silica-based ceramics have been proposed for coating purposes to enhance dental and orthopedic titanium (Ti) implant bioactivity. The aim of this study was to investigate the influence of ...sphene-based bioceramic (CaO.TiO
.SiO
) coatings on implant osseointegration in vivo. Sphene coatings were obtained from preceramic polymers and nano-sized active precursors and deposited by an automatic airbrush. Twenty customized Ti implants, ten sphene-coated and ten uncoated rough implants were implanted into the proximal femurs of ten Sprague-Dawley rats. Overall, cortical and cancellous bone-to-implant contact (BIC) were determined using micro-computed tomography (micro-CT) at 14 and 28 days. Moreover, peri-implant bone healing was histologically and histomorphometrically evaluated. The white blood cell count in the synovial fluid of the knee joints, if present, was also assessed. No difference in the BIC values was observed between the sphene-coated and uncoated implants, overall and in the two bone compartments (
> 0.05). Delamination of the coating occurred in three cases. Consistently with micro-CT data, the histological evaluation revealed no differences between the two groups. In addition, no synovial fluid could be collected on the test side, thus confirming sphene biocompatibility. In conclusion, sphene coating was found to be a suitable material for biomedical applications. Further studies are needed to improve coating adhesion to the implants.
Stereolithography based 3D printing provides an efficient pathway to fabricate alumina ceramics, and the exploration on the mechanical properties of 3D printed alumina ceramics is crucial to the ...development of 3D printing ceramic technology. However, alumina ceramics are difficult to sinter due to their high melting point. In this work, alumina ceramics were prepared via stereolithography based 3D printing technology, and the improvement in the mechanical properties was investigated based on the content, the type and the particle size of sintering aids (TiO2, CaCO3, and MgO). The flexural strength of the sintered ceramics increased greatly (from 139.2 MPa to 216.7 MPa) with the increase in TiO2 content (from 0.5 wt% to 1.5 wt%), while significant anisotropy in mechanical properties (216.7 MPa in X-Z plane and 121.0 MPa in X–Y plane) was observed for the ceramics with the addition of 1.5 wt TiO2. The shrinkage and flexural strength of the ceramics decreased with the increase in CaCO3 content due to the formation of elongated grains, which led to the formation of large-sized residual pores in the ceramics. The addition of MgO help decrease the anisotropic differences in shrinkage and flexural strength of the sintered ceramics due to the formation of regularly shaped grains. This work provides guidance on the adjustment in flexural strength, shrinkage, and anisotropic behavior of 3D printed alumina ceramics, and provides new methods for the fabrication of 3D printed alumina ceramics with superior mechanical properties.
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Ti6Al4V components, for biomedical and aerospace sectors, are receiving a great interest especially after the advent of additive manufacturing technologies. The most used techniques are Selective ...Laser Sintering (SLS), Selective Laser Melting (SLM) and Electron Beam Melting (EBM). In the current research, we developed 3D-printed Ti6Al4V scaffolds by Direct Ink Writing (DIW) technology. Appropriate ink formulations, based on water-titanium powder suspensions, were achieved by controlling the rheological properties of the developed inks. After printing process, and drying, the printed components were sintered at 1400 °C under high vacuum for 3 h. Highly porous titanium scaffolds (with porosity up to 65 vol%) were produced and different geometries were printed. The influence of the porosity on the morphology, compression strength and biocompatibility of the scaffolds was investigated.
•Different scaffolds geometries were printed possessing struts nominal size of 800 micron.•Porosity was designed in order to assess its effect on struts microstructure, compression strength and biocompatibility•We demonstrated the high quality of the produced ink so as the good control on processing parameters.•A preliminary in vitro result indicated that 3D printed Titanium scaffolds allowed cell attachment and proliferation
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Metakaolin-based geopolymer foams were synthesized by mechanical frothing, using hydrogen peroxide as additional foaming agent; three vegetable oils were added in order for the saponification ...reaction to occur. The combined use of the two foaming techniques (mechanical frothing and H2O2 decomposition) led to interconnected porosity: the in-situ formation of the soap molecules generated by the saponification reaction was exploited to generate macro-porosity. This combined route enabled the production of geopolymer foams with a range of total porosity and strength values, with an optimal sample possessing a total porosity of to ∼81vol%, an open porosity of ∼79vol%, and a compressive strength of ∼3.1MPa. Moreover, factors that influence the compressive strength, the porosity, and the pore size distribution were investigated. The results showed that the cell size and cell window size can be controlled by adding different oils and different contents of peroxide.
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The electromagnetic waves (EMW) absorption properties of SiOC ceramics synthesized by polymer-derived method were investigated, and additive manufacturing was employed to obtain the integration of ...structure and functions. The presence of free carbon and β-SiC nanocrystallites increased the internal relaxation interfacial polarization, which improved the EMW absorption properties significantly. In particular for the sample pyrolyzed at 1200 °C, the effective absorption bandwidth (EAB, RL<-10 dB) and minimum reflection loss (RL)were 4.9 GHz (at a thickness of 1.58 mm) and -23.5 dB, respectively, indicating the excellent EMW absorption properties of this SiOC material. In addition, we 3D printed two typical porous structures (a log-pile grid and a gyroid) in which the thickness of solid element corresponded to the one providing optimal absorption. Additive Manufacturing of designed structures will enable to improve and further optimize the selection and control of the absorbing material in practical applications.
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49.
Direct ink writing of geopolymeric inks Franchin, Giorgia; Scanferla, Paolo; Zeffiro, Luca ...
Journal of the European Ceramic Society,
06/2017, Volume:
37, Issue:
6
Journal Article
Peer reviewed
The development of geopolymeric inks with optimized rheological properties for DIW is presented; several inks with different water content and additives were compared to determine which parameters ...enable extrusion as well as shape retention. It is a challenging task, because the inks are subjected to ongoing poly-condensation reactions which continuously modify their rheological properties over time.
Highly porous ceramic lattices (porosity up to ∼71vol%) were fabricated with ∼0.8mm struts and unsupported features with very limited sagging. Their physical and mechanical properties were characterized and correlated. Our approach can be successfully extended to other formulations.
Geopolymeric foams have recently been proven as suitable for water filtration; the use of precisely designed, non stochastic printed structures could enhance the mechanical properties of the porous components, provide a better control of pressure drop and fluid dynamics inside the part and improve their performances consistently.
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Aiming at optimizing the performance of porous ceramics through structural optimization, this work explored the properties variation achieved by designing different patterns in SiOC log-pile ...structures fabricated by direct ink writing. Specifically, we investigated the effect of filament diameter, spacing between filaments and angle of deflection between adjacent layers on the compression strength and gas permeability of these structures. Results confirm that mechanical performance could be tuned by designing the structures’ architectural features, such as the spacing between filaments and the angle of deflection between layers, leading to changes in the contact area of filaments belonging to adjacent layers. Permeability decreased with varying angle of deflection from 90 ° to 15 °, due to the higher tortuosity of the flow paths. This enables to optimize the strength and permeability of the structure without reducing the porosity of the component.
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