Ceramic Paste Research Articles

Preparation, characterization and coloring mechanism of 3D printed colorful ZrO2 ceramics parts

ZrO 2 ceramics are widely concerned with aesthetic decoration materials. It has a relative good resultant mechanical properties among ceramics, and it also can be provided with the beautiful colors blending the additives to reach the best artistic effect. This work mixed the colorful ZrO 2 ceramic pastes with Co 3 O 4 , Cr 2 O 3 and Er 2 O 3 , respectively, formed the colorful ZrO 2 ceramic parts by SLA-3D printing technology, and then sintered the colorful ZrO 2 ceramic parts at high temperature. The coloring mechanism of colorful ZrO 2 ceramic parts was investigated and the optimum printing process was obtained. The results indicated that when the cobalt oxide contents is not exceed 5 wt.%, the color of zirconia ceramic parts can be changed enough. The coloring quality of blue zirconia ceramics was mainly dominated by the forming of oxides of Al, Co and O elements. The final coloring quality of zirconia ceramics with chromium oxide was mainly determined by the forming of a solid solution containing Al, Cr and O elements. Finally, the pink, green and blue colorful school emblems of Shandong University with complex shapes were prepared successfully, which verifies the feasibility of our proposed scheme of aesthetic decoration material preparation.

The study of rheology, dielectric, ferroelectric, energy storage properties of Mg-doped Na0.425Bi0.425Ca0.15TiO3 lead-free ceramics through a viscous polymer process

Lead-free relaxor ferroelectric ceramics 0.95Na 0.425 Bi 0.425 Ca 0.15 TiO 3 -0.05 Mg with different polyvinyl alcohol contents (NBCT-Mg- x PVA) were prepared by viscous polymer processing to generate high density and induce high breakdown strength (BDS) and high recoverable energy storage density ( W rec ). The rheology properties of the ceramic pastes had been systematically studied. The content of PVA has exhibited a great influence on the microstructure and property of ceramics. Through the analysis of ceramics with different PVA contents, it is found that the less PVA content, the less pores and greater BDS on the premise of film formation. The related other electrical performances of the resulting ceramics have also been performed. Especially for the NBCT-Mg-0.4PVA ceramics, the BDS of it reached as high as 320 kV/cm, and the W rec was 4.51 J/cm 3 , which also exhibited excellent temperature stability (30–135 °C) and frequency stability (0.2–50 Hz), as well as good stability during charged-discharged process and achieve high power density.

Maya molded-carved ceramics as boundary objects: Terminal classic ceramic production and the forging of political relations in the mopan valley of Guatemala

• Terminal Classic period Mopan Valley potters produced a range of decorated serving vessels including ‘Ahk’ utu’ Molded-carved, Portia Molded-carved, and Local Fine Orange ceramics. • In addition to producing their own ceramics, inhabitants of the middle Mopan Valley sites of Ucanal, La Blanca, and Calzada Mopan had access to ceramics produced in or close to the Upper Belize Valley, the Holmul River, and the Usumacinta River region, underscoring their diverse social and political relationships throughout the Southern Maya Lowlands. • Microphotography and portable X-ray fluorescence (pXRF) analyses of ceramic pastes complement visual typology studies to provide a more holistic perspective of archaeological ceramics that can address both different and overlapping pottery communities of practice. • We find that Terminal Classic polities often shared in an overlapping network of ceramic production and gift exchange that bridged different political communities, a pattern that contrasted with the most elaborate polychrome ceramic traditions of the earlier Late Classic period, which were more highly controlled and circumscribed in nature. Fine Orange ceramics, speciality serving wares of the Terminal Classic (ca. A.D. 810–950/1000) in the Maya area, have long been implicated in the identification of changing political and social relationships. Some previously subordinate political centers thrived during this time as many of the dominant Classic polities were embroiled in crises and reductions in their populations. This paper examines molded-carved Fine Orange and “imitation” Fine Orange ceramics from a trio of closely-located sites that prospered during the Terminal Classic period: Ucanal, La Blanca, and Calzada Mopan in the middle Mopan Valley in Petén, Guatemala. Chemical paste analyses using a portable X-ray fluorescence instrument, microphotography, and traditional Ware-Type-Variety analyses reveal that potters in this region did not blindly imitate Fine Orange ceramics, but picked and chose techniques and designs that drew from multiple communities of practice. Furthermore, these sites had access to decorative serving vessels that were produced in multiple regions throughout the Southern Maya Lowlands, placing them at an important nexus of political, economic, and social interaction. We argue that molded-carved and other decorated ceramics served as boundary objects, which articulated different pottery producing communities and forged marriage and political ties between different polities in a new decentralized political landscape.

High-performance integrated manufacturing of a 3Y-TZP ceramic crown through viscoelastic paste-based vat photopolymerization with a conformal contactless support

Ceramic vat photopolymerization has been one of the promising three-dimensional printing technologies for personalized zirconia crown with high dimensional accuracy and surface topography. However, insufficient material stability and complex procedure about auxiliary supports limit the application based on low viscosity slurry. In this work, we developed a photocurable ceramic paste, in which the high static viscosity and high yield stress characteristics allowed it to exhibit sufficient anti-settling and self-supporting capabilities. The rheological characteristics of the as prepared paste were measured by stress-controlled rheometer, and conformal contactless support was designed including top conformal structure without contact with the crown and appropriate empty layer. The 3D precision of crown was evaluated by laser scanning confocal microscope and optical surface scanner. In addition, mechanical properties and biocompatibility of sintered samples were systematically evaluated. The results demonstrated that the yield stress of the ceramic paste approached around 600 Pa, and integrate morphology at the bottom of the crown with the contactless supported zone was observed. 3D deviation between the printed crown scan data and the reference model was reduced within the range of 40–70 µm. Finally, the flexural strength and fracture toughness of the sintered zirconia ceramics reached 1117 MPa and 7.76 MPa⋅m 1/2 , respectively, as well as good biocompatibility by the lack of cytotoxicity and hemolytic reaction. The results indicate an important practical significance for the development of vat photopolymerization printing technology of viscoelastic paste and conformal contactless support strategy to realize the integrated manufacturing of ceramic crowns.

Optimal trajectory smoothing for direct energy deposition additive manufacturing processes

In free form additive manufacturing processes (e.g., metal blown powder, glass filament, ceramic paste extrusion), part quality depends on both the rate at which the part is built and where material is deposited. This creates a natural conflict between these two criteria at locations where the curvature of the programmed path is small, such as corners, because at these locations it is not possible to precisely follow the path without changing acceleration and, hence, varying the part build rate due to the variation in path velocity. In some additive manufacturing processes it is not possible to easily vary the material feed rate to maintain a constant part build rate when path velocity varies; thus, uneven material deposition occurs. In this work an optimal trajectory smoothing methodology is created that formulates the path following problem as an optimal dynamic system boundary value problem. The methodology naturally allows a trade-off between path following error and velocity error and is experimentally applied in a blown powder direct metal deposition additive manufacturing process. The results show that path and velocity errors increase as the corner angle decreases and the velocity entering the corner increases; however, they can be decreased by increasing the corner's leg length. Further, as the weight on velocity error increases, the velocity error, excess deposited material, and total print time decrease asymptotically while path error increases asymptotically.

Археометрические исследования сфероконических сосудов из раскопа CС Болгарского городища: местное производство и алхимическое назначение?

The paper addresses the study of the chemical composition of paste used in 26 fragments of sphero-conical vessels from the CC dig of the Bolgar settlement. Complex analytical studies, including optical and electron microscopy, mass spectrometry and emission spectral analysis, were carried out to identify the possible functional purpose of the vessels, as well as to identify potential raw material sources. Areas in the vicinity of the Bolgar settlement were identified, where the composition of the clay is similar to the composition of the ceramic paste. The peculiarity of “mercury — arsenic” ratio in the ceramic clay allowed to make an assumption about their original alchemical nature.

Artisanal experiences in Arpi: Colours and raw materials of Apulian red figure production

This work aims at studying the manufacturing and technology peculiarities of Apulian red figure (4th − 3rd century BCE) production from Arpi. In particular, the relationship between the red figure production from Arpi with coeval pottery of different classes retrieved in the same contexts in Arpi is investigated, as well as the connection between the red figure production from Arpi and same class vases from different Apulian sites. This goal has been achieved through widening the archaeometrical studies so far performed to red figures finds from two more tomb complexes in Arpi – i.e. tomb of the Niobids vase and 4/2004 tomb – and also organically reorganizing the so far obtained experimental data on Arpi findings of various ceramic classes. The systematic characterization of red figure vases was obtained by Inductively Coupled Plasma Mass Spectrometry (ICP-MS), Scanning Electron Microscopy (SEM) with Energy Dispersive X-ray Spectroscopy (EDS), Powder X-ray diffraction (PXRD) and Raman Spectroscopy. Analytical data allow to define the elemental and mineralogical composition of ceramic pastes and identify pigments and coatings.The results allow to validate the archaeological hypotheses that Arpi red figure production is different from the one from other Apulian areas and that pictorial experiences were shared among tombs, domus and ceramic production in Arpi.

The production of western Greek amphorae in Agrigento (Southern Sicily): An archaeometric and archaeological characterisation of the late 6th-4th centuries BCE series

This paper aims at an interdisciplinary, archaeological and archaeometric characterisation of the western Greek amphorae series produced in late Archaic and Classical-period Agrigento (southern Sicily). The research is based on a macroscopic examination, according to the standardised methods of Fabrics of the Central Mediterranean (FACEM), combined with petrographic analyses of 21 amphorae samples of presumed local fabric found in Agrigento itself. These were found in the artisanal area outside Porta V, in the excavations South of the temple of Zeus, and in several Sicilian consumption sites. Furthermore, a selection of 12 coarse ware samples and three tiles, all of supposed local manufacture and unearthed in Agrigento, has been investigated. For comparison, 12 raw clays sampled in the gullies between the Tempio di Giunone and the Tempio della Concordia have been included in this study and are complimented by chemical analyses (ICP-MS and ICP/OES) undertaken on a group of 19 ceramic samples and seven raw materials. As a result, our study confirms the local manufacture of the entire selection of 36 ceramic samples and the more than acceptable petrographic and chemical homogeneity of the ceramic pastes produced with locally sourced clays. The identification of a production of western Greek wine (?) amphorae in Agrigento dating from the late 6th-4th century BCE breaks ground for a better understanding of the colony’s economic development during the late Archaic and Classical periods. The city has to be regarded, in fact, as one of the major global players within the wider frame of Sicilian commercial interaction, especially during the 5th century BCE.

Rheological behavior and curing deformation of paste containing 85 wt% Al2O3 ceramic during SLA-3D printing

The preparation of high solids loading Al 2 O 3 paste is of great significance for improving the properties of ceramics formed by UV-curing. However, the solid contents of alumina slurry used by digital light processing (DLP) and traditional alumina paste for stereolithography (SLA) are both less than 80 wt%. With increase in solid content, the viscosity of paste increases sharply, and rheological property deteriorates. In this study, ceramic paste containing 85 wt% (62 vol%) Al 2 O 3 was prepared for SLA-3D printing of ceramics, and more than 85 wt% solid content was achieved by dispersant and other additives. Effects of different dispersants on rheological and curing properties of Al 2 O 3 ceramic paste were studied. At room temperature, the viscosity of 85 wt% Al 2 O 3 ceramic paste was 51733 mPa s at shear rate of 30 s −1 . A novel method was proposed to control curing deformation of parts during printing. As-manufactured ceramic did not show any cracks by naked eye and exhibited excellent mechanical properties, with three-point bending strength of 540 MPa, fracture toughness of 4.19 MPa m 1/2 , Vickers hardness of 16 GPa, surface roughness of 0.463 μm, and density of 3.86 g/cm 3 .

CERAMIC RAW MATERIAL ANALYSIS FROM KYIV POST-MEDIEVAL POTTERY CENTERS

According to written and archeological sources, there were 12 pottery-making sites in the nowadays territory of Kyiv. During the last 50 years, seven pottery production sites have been archaeologically discovered (kilns, clay pits, outbuildings, warehouses, semi-finished product stocks, etc.). In general, we have information on at least about 27 pottery kilns and a stock of semi-finished products. All of them can be dated to different times from the turn of the 16th—17th centuries to the middle 19th century.
 Pottery production sites were rather big, with high-quality production using various decoration and glazing techniques, and a wide selection of products; some of them used underglaze painting. Numerous potsherds, both ready-to-use and semi-finished products, were discovered in the filling of kilns and related structures. Used for ceramic paste clay was exceptionally good, mainly light — from white to yellowish or pinkish colors, but sometimes the examples of darker colors can be met, like reddish or brownish. The red color was used for the decoration of unglazed white ware; white, green, and red colors were applied for underglaze painting ceramics.
 We have analyzed the chemical composition of 38 samples from five sites with the PIXE and XRD methods. According to the analyses, not all clays are pure kaolinite, some are a mixture of hydromica and kaolinite. Iron can be present in different clays. Components that are present in small amounts are characteristic of clays from the Ukrainian Shield. The presence of phosphorus in pigments is associated with the addition of bone meal. Calcium in those cases, where it is insignificant, is part of the clay, and where there is a lot of it, it is obviously associated with lime plaque on the surface of the watering.
 Some of the products were decorated with paintings. Red paint was used for it on the unglazed ware and white, green, brown, red — for glazed paintings. These paints were also analyzed. Fragments of ceramics after the first firing are covered with a white engobe, over which the painting is applied, but they do not yet have a covering layer of glaze, which made it possible to determine the composition of dyes without the admixture of glaze.
 For the painted dishes white kaolin clay was used as an engobe base for painting. Probably red iron clay was used as pigments for painting non-painted ware (erratum). For glaze painting, additional iron oxide was added to brown and black paints — possibly bog ore. The paints with the addition of copper after the first firing have a gray color with a greenish tint, and when re-fired under watering, they acquire a bright green color.

The Santa María pottery of El Bolsón valley (Catamarca, Argentina): Compositional characterization and implications on the elaboration processes, ca. 1000–1600 ce

AbstractThe results obtained from the multi‐analytic compositional characterization of ceramic pastes and paints of the Santa María style, from the El Bolsón valley (Belén Department, Catamarca Province, Argentina), are presented here. This pottery style had a wide regional distribution in Northwestern Argentina between ca. 1000 and1600 ce and is characterized by its complex iconography painted in black, cream and red. The analyses show that the containers correspond to the technical tradition of using grog temper and suggest that its manufacture involved a double firing process. This reveals a new practice for the time.

Novel method of ancient pottery analysis based on radioactive isotope ratios: a pilot study

The proposed method has been applied to a multi-phased settlement complex and pottery manufacturing centre in Ostrowite in northern Poland. In this study the radioactive isotope ratios method has been applied to a set of ceramic pottery specimens from the same multi-layered archaeological site and probably produced from local raw material. The pilot radiometric research was based on: 24 Neolithic (5200–5000 BCE), 21 Early Iron Age (800–600 BCE), 4 Roman Period (100–400 CE), and 13 Middle Ages (1030–1320 CE) pottery fragments, and also 8 samples of local clay (glacial till) and 3 burned clay samples. The method shows the similarities within the ceramic material used to manufacture the pottery. The variations in the quantitative and qualitative compositions of the basic products (clay, silt, loam, sand, ash and organic admixtures) used in the preparation of the ceramic paste change the isotopic composition and activity ratios. Pottery from each ceramic manufacturing centre, based on the specific composition of the raw materials, have characteristic isotope ratios. Radioactive isotope ratios as fingerprints of ancient ceramic manufacturing centres have not yet been applied as an archaeometric method. In this study two isotope ratios have been selected and applied: 40K/228Ac and 226Ra/208Tl. All analysis have been done using gamma spectrometry system, with quality and quantity analysis of the spectrums. Low-background passive shield was used for obtain improvement of results quality. The pilot study confirms the grouping of isotope ratio results for each sample type, even in terms of similarities with the base clay material collected in this region.

Forging a New World Order? Interdisciplinary Perspectives on the Management of Metalworking and Ideological Change in the Late Bronze Age Carpathian Basin

The Carpathian Basin was a highly influential centre of metalworking in the 2nd mil. BC. Nevertheless, despite the abundance of metal objects from the Late Bronze Age, the scarcity of contextually associated metalworking remains representing distinct phases of the metalworking cycle from this region is striking. Here, we explore Late Bronze Age metalworking through the lens of a uniquely complete metalworking assemblage from the site of Șagu from contexts spanning the sixteenth to early thirteenth century BC. This material provides insights into changes in craft organisation following socio-political change after the collapse of Middle Bronze Age tell-centred communities. Our approach combines analytical and experimental data together with contextual analysis of technical ceramics (crucible, mould, and furnace fragments) to reconstruct the metalworking chaîne opératoire and place Șagu in its broader cultural context. Analyses demonstrate clear technological choices in ceramic paste recipes and strong interlinkages between metallurgy and other crafts practised on site, from domestic pottery production to building structures. Experimental replications reveal important intrinsic and experiential aspects of metallurgical activities at Șagu. Evidence on the spatial organisation of metallurgical workflows (routine sequence of actions and decisions) suggests they incorporated a high degree of visibility, which marks a distinct change in the use of craft space compared to the context of densely occupied Middle Bronze Age tells nearby. Combined, our archaeometric, experimental, and contextual results illustrate how changes in metalworking activities in the Late Bronze Age Carpathian Basin were deeply embedded in an ideological shift in the aftermath of the breakdown of Middle Bronze Age tells and the emergence of new social structures.

Efficient cleaning of ceramic green bodies with complex architectures fabricated by stereolithography-based additive manufacturing via high viscoelastic paste

Complete removal of uncured ceramic paste from the surface of a green body with complex profiles fabricated by stereolithography-based additive manufacturing is critical to the ultimate achievement of the designed 3D part with high definition and ideal surface roughness. The present work provided a novel cleaning strategy for the design of cleaning agents on the basis of competitive absorption of viscosity-reducing dispersants on the surface of ceramic particles within viscoelastic pastes. In combination with cleaning agent design and auxiliary cleaning equipment, distinct dispersants were selected to enhance the flowability of the uncured paste during the ultrasonic cleaning and spraying processes. The morphology and reconstruction characteristics of specific structures illustrated the advantages and disadvantages of the two cleaning methods. The cleaning effect for small holes by ultrasonic cleaning was superior, but the structural damage of the green body was more serious. After spray cleaning, the surface roughness was lower with less damage to the green body, and there was less residual paste after cleaning. The results demonstrated that the selection of a cleaning strategy was beneficial to posttreatment of stereolithography-fabricated ceramic green bodies, achieving subsequent superior surface quality and accuracy of the internal feature size.

Automated SEM Mineralogy and Archaeological Ceramics: Applications in Formative Period Pottery From the Atacama Desert

The analysis of archaeological ceramics has rapidly evolved over the last decades by the application of new analytical techniques. An emerging analytical proposal to fully characterise archaeological ceramics using automated SEM mineralogy is presented. A case study is provided of sets of ceramics from the San Pedro de Atacama oases in the Atacama Desert, northern Chile. Ceramic fragments of different typologies (i.e., Los Morros, Loa Café Alisado and San Pedro Negro Pulido) found in the Ghatchi archaeological sites are analysed. Our results include automated mineralogical maps, which are used to define the components that form the ceramic pastes, i.e., clay matrix and non-plastic inclusions, as well as grain size and mineral abundance information. We show that the pastes that define the studied ceramic types are more complex than previously suggested. The overall composition for these pastes corresponds to clay mineral-rich matrices containing non-plastic inclusions, such as mineral grains, crushed ceramic fragments, and sedimentary to igneous rock fragments, that may vary in composition, size, and abundance among the studied ceramic types. This mineralogical information allows us to discuss possible sources of raw materials by comparing these paste components with geological information. Here we interpret Los Morros and Loa Café Alisado as foreign ceramic types to Ghatchi, whereas the San Pedro Negro Pulido fragments found in this site agree well with the pottery paste recipe typically recognised in the San Pedro de Atacama oases. The petrographic-approach employed here supports the automated SEM mineralogy as a valid option for archaeometric studies of ceramic pastes since includes precise quantitative data formulated from the chemical composition of each component of the paste, which may provide valuable evidence into raw materials and technological styles.

3D printable ceramic pastes design: Correlating rheology & printability

Binder-free ceramic pastes based on TiO2 nanoparticles (64 wt%) with different solvent:co-solvent volumetric ratios (water:glycol, W:G) are disclosed for the first time. Ceramic pastes were prepared without binders (polymers or gel-precursors) using a straightforward, and environmentally respectful method. Two criteria to achieve three-dimensional and complex structures were proposed. 1.- shear-thinning ability and 2.- G' = G'' > 1 × 103 Pa. Pseudoplastic behaviors were found and were suitably modeled for all pastes analyzed, fulfilling the first criterion. Nonetheless, only those pastes with 60:40, 50:50, and 40:60 (W:G) fulfilled the second criterion. These latter exhibited a good balance between rigidity to form long and horizontal bridges but fluid enough to avoid flow cuts or clogs. Thus, 3D structures (20 layers of stacking) were obtained with outstanding self-supporting and excellent shape-retention. The complex structures were dried at 400 °C, thus obtaining binder-free and mechanically stable ceramic structures preserving their printed shape.

Translucency of a Dental Porcelain Mixed by Two Ceramic Slurry Methods: A Bayesian Comparison.

Background The ceramics industry produces porcelain pastes using a controlled ratio of water and porcelain powder. Two methods are used to produce a dental porcelain paste: one-step mixing or incremental mixing. Objective To evaluate the optical properties of a feldspathic dental ceramic using two different ceramic paste preparation methods using a Bayesian approach. Materials and Methods Two groups of feldspathic porcelain discs, an incremental mixing group (n = 40) and a one-step mixing group (n = 40), were assessed. Groups were evaluated using spectrophotometry, and the translucency parameter (TP) of each sample was calculated. Surfaces were characterized by AFM and SEM. Statistical analysis was performed using a Bayesian approach. Results Translucency parameter values of the incremental mixing group ranged from 1.65 to 3.41, while values for the one-step mixing group ranged from 3.62 to 5.74, this difference being statistically significant. The lowest roughness was obtained on the surface of discs in the one-step mixing group. Conclusions Feldspathic porcelain with lower translucency and higher roughness was obtained using the incremental mixture method.

An exploration of the ceramic technology of a northern Chilean community, evidence from the Caleta Vitor Archaeological Complex

This paper discusses the results of statistical analyses of the domestic ceramic assemblage from the Caleta Vitor Archaeological Complex, northern Chile, a collection that spans 2500 years. Mineralogical analyses were also conducted on a selection of the ceramic sherds using X-ray diffraction (XRD) as well as paste and petrographic analyses. The results of this study correspond with prior research (Bland et al., 2017a) which concluded that the majority of domestic ceramics from the Caleta Vitor Archaeological Complex were manufactured using local resources. Here, we expand this discussion by identifying four ceramic paste groups that would constitute local pottery traditions of manufacture. The identified paste groups are relatively consistent and span almost all time periods examined (Formative c. 4000–1500 BP through to Hispanic c. 467 BP Periods). These results support the argument that these ceramic traditions were maintained by the coastal communities of Caleta Vitor, despite the fact that they were integrated into interregional networks of interactions through time, including their relationships with powerful Andean polities. These apparent continuities in domestic ceramic production allow us to reflect on local decision-making processes throughout relevant cultural phases, and to conclude that foreign pottery did not have an exchange value.

Additive Manufacturing of Hydroxyapatite Bioceramic Scaffolds with Projection Based 3D Printing

Hydroxyapatite (HA) bioceramics have garnered considerable attention owing to their applications in the field of bone repair and excellent biocompatibility. Compared to extrusion-based 3D printing, projection-based 3D printing (3DPP) can fabricate parts with complex geometry, high accuracy, and efficiency, which is very promising for bioceramic scaffolds. However, conventional 3DPP using a paste with low viscosity will cause severe shrinkage of the parts after sintering, which makes it unsuitable for bioceramic scaffolds, and a system investigation of the printing process remains insufficient. In this study, we proposed a 3DPP device suitable for bioceramic scaffolds and investigated the additive manufacturing of HA scaffolds. Ceramic paste properties and process parameters of curing, debinding, and sintering were initially examined. The mechanical properties, shrinkage, and biocompatibility in vitro of the sintered samples were further investigated. The obtained results indicate that HA bioceramics with uniform morphology, complex structure, and high accuracy can be manufactured using the 3DPP equipment. HA scaffolds have the mechanical strength of human cancellous bone, while HA scaffolds cultured with osteoblast precursor cells possess strong biocompatibility and can promote osteoblast adhesion, proliferation, and differentiation. These results suggest a promising application of the 3DPP technique in the preparation of bioceramic scaffolds, and the HA scaffolds fabricated using the 3DPP technique exhibit promising potential in fulfilling a constructive role in the biomedical field of human bone regeneration repair.

Shear-thinning sacrificial ink for fabrication of Biosilicate® osteoconductive scaffolds by material extrusion 3D printing

Osteoconductive scaffolds are required to stimulate and enhance the regenerative potential of cells in bone tissue engineering applications. Additive manufacturing (AM), popularly known as 3D printing, has been widely used to fabricate these porous structures. In this study, bioceramic scaffolds based on highly bioactive glass-ceramic (Biosilicate®) were developed and characterized using a hydrogel as sacrificial ink for material extrusion 3D printing. A paste containing Biosilicate as solid filler was developed from a sacrificial ink whose formulation is based on poly(ethylene glycol) (PEG-400) with 7.5% (w/w) Laponite® nanoclay as rheological modifier. Initially, the rheological behaviors of the sacrificial ink (PL) and of the ceramic paste with 70% (v/v) Biosilicate (PL-BioS) were evaluated. Viscosity of the PL increased with addition of Biosilicate, showing a shear-thinning behavior appropriate to material extrusion 3D printing. After that, samples were 3D printed and dried at 20 and 50 °C. The dimensional characteristics of the samples were evaluated and compared, and showed that drying at 20 °C resulted in lower degree of shrinkage and mass loss before sintering. Preliminary heating stage microscopy tests were performed to define the sintering parameters, and then the scaffolds were sintered at 900 °C for 5 h at a heating rate of 1 °C/min. The sintered scaffolds were analyzed by FTIR, XRD, and SEM. These characterizations showed that the PL was eliminated from the structure with no significant change in scaffold composition, which remained intact after this process, and that the residual Laponite improved scaffold strength with formation of micropores internally to the filaments. An in vitro biological study confirmed the nontoxic behavior of the developed scaffolds on NHI-3T3 fibroblast-like cells, showing suitable cell adhesion, growth and proliferation on their surface, which are associated with good osteoconductive properties. In conclusion, the use of PL gels combined with Biosilicate is promising for ceramic ink formulation, considering that shear-thinning materials facilitate the 3D printing process. Moreover, preliminary mechanical and biological results reveal the potential of the sintered scaffolds for use in bone tissue engineering.