ORCID Profile
0000-0002-8649-9388
Current Organisation
CSIRO
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Publisher: Elsevier
Date: 2022
Publisher: Elsevier
Date: 2022
Publisher: Springer Science and Business Media LLC
Date: 03-04-2011
DOI: 10.1007/S10856-011-4307-6
Abstract: The high-velocity suspension flame spraying technique (HVSFS) was employed in order to deposit 45S5 bioactive glass coatings onto titanium substrates, using a suspension of micron-sized glass powders dispersed in a water + isopropanol mixture as feedstock. By modifying the process parameters, five coatings with different thickness and porosity were obtained. The coatings were entirely glassy but exhibited a through-thickness microstructural gradient, as the deposition mechanisms of the glass droplets changed at every torch cycle because of the increase in the system temperature during spraying. After soaking in simulated body fluid, all of the coatings were soon covered by a layer of hydroxyapatite furthermore, the coatings exhibited no cytotoxicity and human osteosarcoma cells could adhere and proliferate well onto their surfaces. HVSFS-deposited 45S5 bioglass coatings are therefore highly bioactive and have potentials as replacement of conventional hydroxyapatite in order to favour osseointegration of dental and prosthetic implants.
Publisher: American Vacuum Society
Date: 11-2020
DOI: 10.1116/6.0000557
Abstract: Additive manufacturing (AM) of orthopedic implants is growing in popularity as it offers almost complete design flexibility and freedom, meaning complex geometries mimicking specific body parts can be easily produced. Novel composite materials with optimized functionalities present opportunities for 3D printing osteoconductive implants with desirable mechanical properties. Standard metals for bone implants, such as titanium and its alloys, are durable and nontoxic but lack bioactivity. Bioactive glasses promote strong bone formation but are susceptible to brittle failure. Metal-bioactive glass composites, however, may combine the mechanical reliability of metals with the bone-bonding ability of bioactive glasses, potentially reducing the incidence of implant failure. Processing such composites by AM paves the way for producing unprecedented bespoke parts with highly porous lattices, whose stiffness can be tailored to meet the mechanical properties of natural bone tissue. This Perspective focuses on titanium-bioactive glass composites, critically discussing their processability by AM and highlighting their potential as a next-generation implantable biomaterial.
Publisher: Trans Tech Publications Ltd.
Date: 15-03-2007
Publisher: Wiley
Date: 28-06-2019
DOI: 10.1002/AMP2.10021
Publisher: Elsevier BV
Date: 07-2019
Publisher: Wiley
Date: 20-06-2019
DOI: 10.1002/AMP2.10020
Publisher: Elsevier BV
Date: 12-2011
Publisher: Elsevier BV
Date: 2006
Publisher: Wiley
Date: 20-02-2012
Publisher: Elsevier BV
Date: 2011
Publisher: Elsevier BV
Date: 06-2009
Publisher: Elsevier BV
Date: 03-2014
Publisher: Wiley
Date: 27-04-2011
Publisher: Elsevier BV
Date: 05-2012
Publisher: Elsevier
Date: 2022
Publisher: Elsevier BV
Date: 2006
Publisher: American Society of Civil Engineers (ASCE)
Date: 04-2022
Publisher: Elsevier BV
Date: 2007
Publisher: Elsevier BV
Date: 2007
Publisher: IOP Publishing
Date: 16-12-2013
DOI: 10.1088/1748-6041/9/1/015005
Abstract: Binary biocomposites were realized by combining yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) with a bioactive glass matrix. Few works are available regarding composites containing zirconia and a relatively high content of glass because the resulting s les are usually biocompatible but not bioactive after thermal treatment. In the present research, the promising properties of the new BG_Ca-K glass, with its low tendency to crystallize and high apatite-forming ability, allowed us to sinter the composites at a relatively low temperature with excellent effects in terms of bioactivity. In addition, it was possible to benefit from the good mechanical behaviour of Y-TZP, thus obtaining s les with microhardness values that were among the highest reported in the literature. After a detailed analysis regarding the thermal behaviour of the composite powders, the sintered bodies were fully characterized by means of x-ray diffraction, SEM equipped with EDS, density measurements, volumetric shrinkage determination, mechanical testing and in vitro evaluation in a simulated body fluid (SBF) solution. According to the experimental results, the presence of Y-TZP improved the mechanical performance. Meanwhile, the BG_Ca-K glass, which mainly preserved its amorphous structure after sintering, provided the composites with a good apatite-forming ability in SBF.
Publisher: Elsevier BV
Date: 02-2020
Publisher: MDPI AG
Date: 28-01-2011
DOI: 10.3390/MA4020339
Publisher: Wiley
Date: 09-2023
Publisher: Elsevier BV
Date: 07-2011
Publisher: Elsevier BV
Date: 2008
Publisher: Elsevier BV
Date: 05-2013
DOI: 10.1016/J.MSEC.2013.01.029
Abstract: Recently several attempts have been made to combine calcium phosphates, such as β-tricalcium phosphate (β-TCP) and, most of all, hydroxyapatite (HA), with bioactive glasses of different composition, in order to develop composites with improved biological and mechanical performance. Unfortunately, the production of such systems usually implies a high-temperature treatment (up to 1300 °C), which may result in several drawbacks, including crystallization of the original glass, decomposition of the calcium phosphate phase and/or reactions between the constituent phases, with non-trivial consequences in terms of microstructure, bioactivity and mechanical properties of the final s les. In the present contribution, novel binary composites have been obtained by sintering a bioactive glass, characterized by a low tendency to crystallize, with the addition of HA or β-TCP as the second phase. In particular, the composites have been treated at a relatively low temperature (818 °C and 830 °C, depending on the s le), thus preserving the amorphous structure of the glass and minimizing the interaction between the constituent phases. The effects of the glass composition, calcium phosphate nature and processing conditions on the composite microstructure, mechanical properties and in vitro bioactivity have been systematically discussed. To conclude, a feasibility study to obtain scaffolds for bone tissue regeneration has been proposed.
Publisher: Elsevier BV
Date: 2023
Publisher: SAGE Publications
Date: 18-06-2018
Abstract: The preparation and thermo-mechanical characterization of composites based on polyamide 11 (PA11) filled with various amounts of both expandable and expanded graphites are presented. Investigation conducted using X-ray diffraction (XRD), scanning electron microscopy and surface area analyses indicated how graphite expanded under the selected processing conditions. The XRD analysis on PA11/graphite composites revealed no change in the crystal form of the PA11, while the presence of diffraction peaks associated to the graphite-stacked lamellae can be still detected. All the investigated composites showed an improvement of the thermal stability and mechanical properties (elastic and storage moduli).
Publisher: Elsevier BV
Date: 10-2012
Publisher: Elsevier BV
Date: 09-2018
Publisher: Wiley
Date: 04-04-2022
Abstract: The progress of Industry 4.0 and the advancement of robotic design are revealing a significant gap in the capabilities of current manufacturing techniques and the selection of materials that are available in electronics. Present‐day electrical systems largely rely on metals, but there is a driving need to develop new electrically conductive objects with a wide range of material properties, including expanded flexibility and softness, and with increasingly complex geometries. Electrically conductive composites can replace traditional metal‐based systems. In particular, thermoplastic composites become electrically conductive with the incorporation of conductive fillers or polymers while retaining to a large extent the processability of the thermoplastic matrix. This is where fused filament fabrication (FFF), an additive manufacturing (AM) technique capable of processing a variety of thermoplastic‐matrix feedstock materials, can be leveraged to create electrically conductive objects with new functionalities. While there is an increasing number of publications describing the FFF of electrical objects such as sensors and circuits, there is no comprehensive review outlining the functioning mechanisms, drawbacks, and advantages of FFF as applied to conductive materials. The present review fills this lacuna by offering a critical analysis of the specific challenges and solutions to promote FFF of electrically conductive polymers and composites.
Publisher: Elsevier
Date: 2022
Publisher: Elsevier BV
Date: 12-2010
Publisher: Elsevier
Date: 2022
Publisher: Elsevier BV
Date: 04-2015
DOI: 10.1016/J.JMBBM.2014.12.017
Abstract: Localised delivery of appropriate biomolecule/drug(s) can be suitable to prevent postoperative infections and inflammation after scaffold implantation in vivo. In this study composite shell scaffolds, based on an internally produced bioactive glass and a commercial hydroxyapatite, were surface coated with a uniform polymeric layer, embedded with thermo-stable polyesterurethane (PU)-based nanoparticles (NPs), containing an anti-inflammatory drug (indomethacin IDCM). The obtained functionalised scaffolds were subjected to physico-mechanical and biological characterisations. The results indicated that NPs incorporation into the gelatin coating of the composite scaffolds: 1) not changed significantly the micro-architecture of the scaffolds in terms of mean pore diameter and pore size distribution 2) increased the compressive modulus and 3) allowed to a sustained IDMC release (65-70% of the loaded-drug) within the first week of incubation in physiological solution. On the other hand, the NPs incorporation did not affect the biocompatibility of composite scaffolds, as evidenced by viability and alkaline phosphatase (ALP) activity of MG63 human osteoblast-like cells.
Publisher: Informa UK Limited
Date: 30-08-2023
Publisher: Elsevier BV
Date: 08-2010
Publisher: Wiley
Date: 26-06-2012
DOI: 10.1002/JBM.A.34271
Abstract: Bioceramic "shell" scaffolds, with a morphology resembling the cancellous bone microstructure, have been recently obtained by means of a new protocol, developed with the aim to overcome the limits of the conventional foam replication technique. Because of their original microstructure, the new s les combine high porosity, permeability, and manageability. In this study, for the first time, the novel bioactive glass shell scaffolds are provided with a gelatin-based biomimetic coating to realize hybrid implants which mimic the complex morphology and structure of bone tissue. Moreover, the presence of the coating completely preserves the in vitro bioactivity of the bioactive glass s les, whose surfaces are converted into hydroxyapatite after a few days of immersion in a simulated body fluid solution (SBF).
Publisher: Elsevier BV
Date: 11-2010
Publisher: Elsevier BV
Date: 2023
Publisher: Springer Science and Business Media LLC
Date: 23-03-2012
DOI: 10.1007/S10856-012-4622-6
Abstract: A new protocol, based on a modified replication method, is proposed to obtain bioactive glass scaffolds. The main feature of these s les, named "shell scaffolds", is their external surface that, like a compact and porous shell, provides both high permeability to fluids and mechanical support. In this work, two different scaffolds were prepared using the following slurry components: 59 % water, 29 % 45S5 Bioglass(®) and 12 % polyvinylic binder and 51 % water, 34 % 45S5 Bioglass(®), 10 % polyvinylic binder and 5 % polyethylene. All the proposed s les were characterized by a widespread microporosity and an interconnected macroporosity, with a total porosity of 80 % vol. After immersion in a simulated body fluid (SBF), the scaffolds showed strong ability to develop hydroxyapatite, enhanced by the high specific surface of the porous systems. Moreover preliminary biological evaluations suggested a promising role of the shell scaffolds for applications in bone tissue regeneration. As regards the mechanical behaviour, the shell scaffolds could be easily handled without damages, due to their resistant external surface. More specifically, they possessed suitable mechanical properties for bone regeneration, as proved by compression tests performed before and after immersion in SBF.
Publisher: Elsevier BV
Date: 11-2010
Publisher: Elsevier BV
Date: 2010
Publisher: SAGE Publications
Date: 2019
Abstract: Lack of interphase compatibility between the fabric and the matrix significantly impairs the load-bearing capacity of textile reinforced mortar (TRM). In this study, we consider the application of two inorganic surface coatings for enhancing the interphase bond properties. Either of two silica-based coatings, namely nano- and micro-silica, were applied to alkali-resistant glass (ARG) and to hybrid carbon–ARG woven fabric. Mechanical performance of TRM reinforced with the uncoated and the coated fabric was compared in uniaxial tensile tests. Mechanical testing provides evidence of a remarkable enhancement in terms of ultimate strength and deformability for the coated specimens. This effect can be ascribed to the improved hydrophilicity of the fibers’ surface and to the activation of pozzolanic reaction at the interphase. In addition, penetration of nano- and microparticles in the bundle of the textile yarns reduces the occurrence of telescopic failure.
Publisher: Trans Tech Publications, Ltd.
Date: 11-05-2022
DOI: 10.4028/P-HXRR02
Abstract: Over the last few years, the effectiveness of textile-reinforced mortar (TRM) composite systems for structural retrofitting has led to the widespread adoption of these materials in the practice and to the issue of up-to-date design guidelines. Nonetheless, the weak interfacial bonding that is frequently observed between matrix and fibres is likely to cause inconsistent failure modes and, generally speaking, to severely limit the reinforcing potential of the textile. A promising solution to tackle this issue consists in treating the surface of the reinforcing fibres with a functional coating to improve the adhesion at the interphase. In this paper, a pilot study is presented to assess the effectiveness of a fully sustainable polymer coating, consisting in polyvinyl alcohol (PVA) loaded with with rice husk ash (RHA) or with a 50/50 mixture of RHA and silica fume (SF). The coating was applied on basalt fabrics to reinforce TRM coupons that were mechanically tested under uni-axial tensile loads. The mechanical properties of the TRM s les were significantly increased by up to 20%, and the peak load was attained at a higher deformability level, which is a clue of the enhanced ductility of the reinforced elements.
Publisher: Elsevier BV
Date: 04-2013
DOI: 10.1016/J.MSEC.2012.11.038
Abstract: Since the 1970s, various types of ceramic, glass and glass-ceramic materials have been proposed and used to replace damaged bone in many clinical applications. Among them, hydroxyapatite (HA) has been successfully employed thanks to its excellent biocompatibility. On the other hand, the bioactivity of HA and its reactivity with bone can be improved through the addition of proper amounts of bioactive glasses, thus obtaining HA-based composites. Unfortunately, high temperature treatments (1200°C÷1300°C) are usually required in order to sinter these systems, causing the bioactive glass to crystallize into a glass-ceramic and hence inhibiting the bioactivity of the resulting composite. In the present study novel HA-based composites are realized and discussed. The s les can be sintered at a relatively low temperature (800 °C), thanks to the employment of a new glass (BG_Ca) with a reduced tendency to crystallize compared to the widely used 45S5 Bioglass®. The rich glassy phase, which can be preserved during the thermal treatment, has excellent effects in terms of in vitro bioactivity moreover, compared to composites based on 45S5 Bioglass® having the same HA/glass proportions, the s les based on BG_Ca displayed an earlier response in terms of cell proliferation.
Publisher: Wiley
Date: 09-2022
Abstract: Fused filament fabrication (FFF), also known as fused deposition modeling, is the leading technology for polymer‐based additive manufacturing. The simplicity, along with the cleanness, the affordability, and the multi‐material capability, are some of the main advantages that have prompted this success. Nonetheless, the uptake of FFF in industry is h ered by the limited functionality of commercial filaments, that are often based on plain thermoplastics. The future growth of FFF into new markets needs a significant improvement of available materials. However, materials requirements in FFF are complicated and often mutually conflicting. Whereas heuristic approaches to materials design imply significant costs in terms of time, energy, and materials, a critical survey of the main requirements that a new material should fulfill in order to be printable and suitable for commercial adoption is still missing. In order to bridge this gap, the present paper analyzes the workflow from filament production to end‐of‐life disposal of printed objects, and, for each step, brings to light the governing materials properties. Wherever possible, practical guidelines are given on acceptable values. Existing lacks of knowledge are identified to direct future studies. The ultimate goal is to provide a road map to making materials development in FFF more efficient.
Publisher: Springer Science and Business Media LLC
Date: 28-12-2011
Publisher: Informa UK Limited
Date: 02-2008
Publisher: Elsevier BV
Date: 10-2020
Publisher: IEEE
Date: 02-05-2022
Publisher: SAGE Publications
Date: 23-08-2020
Abstract: This article purposes on developing and on re-interpreting the numerical results of a topology optimization for a structural component built via additive manufacturing. A critical appraisal of the optimization results is presented by modeling the feasible component with a holistic approach that merges structural and manufacturing requirements. The procedure is expected to provide a design guideline for similar applications of practical relevance, toward an increase of the right-first-time parts that is required to bring additive manufacturing to its full competitiveness. Topology optimization of a steering upright for a Formula SAE racing car was performed by targeting weight minimization while complying with severe structural constraints, like global and local stiffness performance. Cornering, bumping and braking vehicle conditions were considered. The optimization constraints were evaluated via finite element analysis on a reference component, where the loading conditions were retrieved from telemetry data. The reference part was manufactured by computer numerical control machining from a solid aluminum block. Spurred by the interpretation of the topology optimization predictions, a new upright geometry was designed and validated by calculating its stress field and the possible occurrence of Euler buckling. The new upright was 9% lighter than the reference component. The new geometry was analyzed according to Design for Additive Manufacturing principles to choose the orientation on the build platform and the supports’ location and geometry. The part was successfully manufactured and proved consistent with the application.
Publisher: Elsevier BV
Date: 2006
Publisher: Elsevier BV
Date: 2007
Publisher: Wiley
Date: 18-03-2019
Publisher: Elsevier
Date: 2022
Publisher: Springer Science and Business Media LLC
Date: 13-04-2023
DOI: 10.1007/S10845-023-02119-Y
Abstract: Over the past several decades, metal Additive Manufacturing (AM) has transitioned from a rapid prototyping method to a viable manufacturing tool. AM technologies can produce parts on-demand, repair damaged components, and provide an increased freedom of design not previously attainable by traditional manufacturing techniques. The increasing maturation of metal AM is attracting high-value industries to directly produce components for use in aerospace, automotive, biomedical, and energy fields. Two leading processes for metal part production are Powder Bed Fusion with laser beam (PBF-LB/M) and Directed Energy Deposition with laser beam (DED-LB/M). Despite the many advances made with these technologies, the highly dynamic nature of the process frequently results in the formation of defects. These technologies are also notoriously difficult to control, and the existing machines do not offer closed loop control. In the present work, the application of various Machine Learning (ML) approaches and in-situ monitoring technologies for the purpose of defect detection are reviewed. The potential of these methods for enabling process control implementation is discussed. We provide a critical review of trends in the usage of data structures and ML algorithms and compare the capabilities of different sensing technologies and their application to monitoring tasks in laser metal AM. The future direction of this field is then discussed, and recommendations for further research are provided. Graphical abstract
Publisher: Elsevier BV
Date: 2023
Publisher: Elsevier BV
Date: 09-2016
DOI: 10.1016/J.BIOTECHADV.2015.12.013
Abstract: Functionally graded materials (FGMs) are innovative materials whose composition and/or microstructure gradually vary in space according to a designed law. As a result, also the properties gradually vary in space, so as to meet specific non-homogeneous service requirements without any abrupt interface at the macroscale. FGMs are emerging materials for orthopedic prostheses, since the functional gradient can be adapted to reproduce the local properties of the original bone, which helps to minimize the stress shielding effect and, at the same time, to reduce the shear stress between the implant and the surrounding bone tissue, two critical prerequisites for a longer lifespan of the graft. After a brief introduction to the origin of the FGM concept, the review surveys some representative ex les of graded systems which are present in nature and, in particular, in the human body, with a focus on bone tissue. Then the rationale for using FGMs in orthopedic devices is discussed more in detail, taking into account both biological and biomechanical requirements. The core of the paper is dedicated to two fundamental topics, which are essential to benefit from the use of FGMs for orthopedic applications, namely (1) the computational tools for materials design and geometry optimization, and (2) the manufacturing techniques currently available to produce FGM-based grafts. This second part, in its turn, is structured to consider the production of functionally graded coatings (FGCs), of functionally graded 3D parts, and of special devices with a gradient in porosity (functionally graded scaffolds). The inspection of the literature on the argument clearly shows that the integration of design and manufacturing remains a critical step to overpass in order to achieve effective FGM-based implants.
Publisher: Springer International Publishing
Date: 2020
Publisher: Mary Ann Liebert Inc
Date: 02-2020
Publisher: Wiley
Date: 24-06-2009
Publisher: Elsevier BV
Date: 12-2007
Publisher: MDPI AG
Date: 11-08-2018
DOI: 10.3390/MET8080634
Abstract: Laser-based powder bed fusion (L-PBF) is nowadays the preeminent additive manufacturing (AM) technique to produce metal parts. Nonetheless, relatively few metal powders are currently available for industrial L-PBF, especially if aluminum-based feedstocks are involved. In order to fill the existing gap, A357.0 (also known as A357 or A13570) powders are here processed by L-PBF and, for the first time, the fatigue behavior is investigated in the as-built state to verify the net-shaping potentiality of AM. Both the low-cycle and high-cycle fatigue areas are analyzed to draw the complete Wohler diagram. The infinite lifetime limit is set to 2 × 106 stress cycles and the staircase method is applied to calculate a mean fatigue strength of 60 MPa. This value is slightly lower but still comparable to the published data for AlSi10Mg parts manufactured by L-PBF, even if the A357.0 s les considered here have not received any post-processing treatment.
Publisher: MDPI AG
Date: 25-10-2023
Publisher: Elsevier BV
Date: 08-2010
Publisher: Elsevier BV
Date: 2009
Publisher: Elsevier BV
Date: 04-2013
Publisher: Elsevier
Date: 2022
Publisher: Elsevier
Date: 2022
Publisher: Informa UK Limited
Date: 23-06-2019
Publisher: Elsevier BV
Date: 05-2014
Publisher: Informa UK Limited
Date: 10-2008
Publisher: AIP Publishing
Date: 09-2007
DOI: 10.1063/1.2774002
Abstract: The potential and limitations of Rayleigh wave spectroscopy to characterize the elastic depth profile of heterogeneous functional gradient materials are investigated by comparing simulations of the surface acoustic wave dispersion curves of different profile-spectrum pairs. This inverse problem is shown to be quite ill posed. The method is then applied to extract information on the depth structure of a glass-ceramic (alumina) functionally graded material from experimental data. The surface acoustic wave analysis suggests the presence of a uniform coating region consisting of a mixture of Al2O3 and glass, with a sharp transition between the coating and the substrate. This is confirmed by scanning electron microscope with energy dispersive x-ray analysis.
Publisher: Elsevier BV
Date: 07-2023
Publisher: Elsevier BV
Date: 2014
DOI: 10.1016/J.MSEC.2013.09.017
Abstract: In cementless fixation of metallic prostheses, bony ingrowth onto the implant surface is often promoted by osteoconductive plasma-sprayed hydroxyapatite coatings. The present work explores the use of the innovative High Velocity Suspension Flame Spraying (HVSFS) process to coat Ti substrates with thin homogeneous hydroxyapatite coatings. The HVSFS hydroxyapatite coatings studied were dense, 27-37μm thick, with some transverse microcracks. Lamellae were sintered together and nearly unidentifiable, unlike conventional plasma-sprayed hydroxyapatite. Crystallinities of 10%-70% were obtained, depending on the deposition parameters and the use of a TiO2 bond coat. The average hardness of layers with low (<24%) and high (70%) crystallinity was ≈3.5GPa and ≈4.5GPa respectively. The distributions of hardness values, all characterised by Weibull modulus in the 5-7 range, were narrower than that of conventional plasma-sprayed hydroxyapatite, with a Weibull modulus of ≈3.3. During soaking in simulated body fluid, glassy coatings were progressively resorbed and replaced by a new, precipitated hydroxyapatite layer, whereas coatings with 70% crystallinity were stable up to 14days of immersion. The interpretation of the precipitation behaviour was also assisted by surface charge assessments, performed through Z-potential measurements. During in vitro tests, HA coatings showed no cytotoxicity towards the SAOS-2 osteoblast cell line, and surface cell proliferation was comparable with proliferation on reference polystyrene culture plates.
Publisher: MDPI AG
Date: 06-09-2019
DOI: 10.3390/MA12182876
Abstract: Laser Powder Bed Fusion (LPBF) technology was used to produce s les based on the Ti–6Al–4V alloy for biomedical applications. Solid-state phase transformations induced by thermal treatments were studied by neutron diffraction (ND), X-ray diffraction (XRD), scanning transmission electron microscopy (STEM) and energy-dispersive spectroscopy (EDS). Although, ND analysis is rather uncommon in such studies, this technique allowed evidencing the presence of retained β in α’ martensite of the as-produced (#AP) s le. The retained β was not detectable by XRD analysis, nor by STEM observations. Martensite contains a high number of defects, mainly dislocations, that anneal during the thermal treatment. Element diffusion and partitioning are the main mechanisms in the α ↔ β transformation that causes lattice expansion during heating and determines the final shape and size of phases. The retained β phase plays a key role in the α’ → β transformation kinetics.
Publisher: Mark Allen Group
Date: 10-2018
DOI: 10.1016/J.MPRP.2018.04.001
Abstract: The choice of appropriate processing conditions in powder metallurgy and the achievement of the required properties for the final metal components greatly depend on the shape of the solid phase. Powder sinterability, packing density, compressibility, mechanical behavior, reactivity and flowability, among the others, are influenced by particle shape. The present paper offers an informative overview on the role of particle shape in powder metallurgy and provides the basic definitions, qualitative shape descriptors and semi-quantitative shape factors that are essential to better understand the effect of metal particle shape in everyday industrial practice.
Publisher: IOP Publishing
Date: 02-2010
Publisher: Elsevier BV
Date: 08-2010
Publisher: Elsevier BV
Date: 12-2010
Publisher: Elsevier
Date: 2022
Publisher: SAE International
Date: 09-01-2020
Publisher: MDPI AG
Date: 22-11-2018
DOI: 10.3390/MA11122356
Abstract: In spite of the fast growth of laser-based powder bed fusion (L-PBF) processes as a part of everyday industrial practice, achieving consistent production is h ered by the scarce repeatability of performance that is often encountered across different additive manufacturing (AM) machines. In addition, the development of novel feedstock materials, which is fundamental to the future growth of AM, is limited by the absence of established methodologies for their successful exploitation. This paper proposes a structured procedure with a complete test plan, which defines step-by-step the standardized actions that should be taken to optimize the processing parameters and scanning strategy in L-PBF of new alloy grades. The method is holistic, since it considers all the laser/material interactions in different local geometries of the build, and suggests, for each possible interaction, a specific geometry for test specimens, standard energy parameters to be analyzed through a design of experiment, and measurable key performance indicators. The proposed procedure therefore represents a sound and robust aid to the development of novel alloy grades for L-PBF and to the definition of the most appropriate processing conditions for them, independent of the specific AM machine applied.
Publisher: National Library of Serbia
Date: 2010
DOI: 10.2298/SOS1003307B
Abstract: Bioglass? 45S5 is widely used in biomedical applications due to its ability to bond to bone and even to soft tissues. The sintering ability of Bioglass? powders is a key factor from a technological point of view, since its govern the production of advanced devices, ranging from highly porous scaffolds to functionalized coatings. Unfortunately this particular glass composition is prone to crystallize at the temperature required for sintering and this may impair the bioactivity of the original glass. For these reasons, a prerequisite to tailor the fabrication of Bioglass?-derived implants is to understand the interaction between sintering, crystallization and bioactivity. In this work the structural transformations which occur during the heat treatment of Bioglass? are reviewed and a special attention is paid to the sintering and crystallization processes. Moreover the bioactivity of the final glass-ceramics is discussed and some alternative glass formulations are reported.
Publisher: Informa UK Limited
Date: 09-2011
Publisher: MDPI AG
Date: 23-12-2021
DOI: 10.3390/MA15010085
Abstract: Additive manufacturing (AM) is rapidly evolving from “rapid prototyping” to “industrial production”. AM enables the fabrication of bespoke components with complicated geometries in the high-performance areas of aerospace, defence and biomedicine. Providing AM parts with a tagging feature that allows them to be identified like a fingerprint can be crucial for logistics, certification and anti-counterfeiting purposes. Whereas the implementation of an overarching strategy for the complete traceability of AM components downstream from designer to end user is, by nature, a cross-disciplinary task that involves legal, digital and technological issues, materials engineers are on the front line of research to understand what kind of tag is preferred for each kind of object and how existing materials and 3D printing hardware should be synergistically modified to create such tag. This review provides a critical analysis of the main requirements and properties of tagging features for authentication and identification of AM parts, of the strategies that have been put in place so far, and of the future challenges that are emerging to make these systems efficient and suitable for digitalisation. It is envisaged that this literature survey will help scientists and developers answer the challenging question: “How can we embed a tagging feature in an AM part?”.
Publisher: Elsevier BV
Date: 10-2011
Publisher: Wiley
Date: 04-05-2023
DOI: 10.1002/WNAN.1895
Abstract: As scientists discovered that raw neurological signals could translate into bioelectric information, brain–machine interfaces (BMI) for experimental and clinical studies have experienced massive growth. Developing suitable materials for bioelectronic devices to be used for real‐time recording and data digitalizing has three important necessitates which should be covered. Biocompatibility, electrical conductivity, and having mechanical properties similar to soft brain tissue to decrease mechanical mismatch should be adopted for all materials. In this review, inorganic nanoparticles and intrinsically conducting polymers are discussed to impart electrical conductivity to systems, where soft materials such as hydrogels can offer reliable mechanical properties and a biocompatible substrate. Interpenetrating hydrogel networks offer more mechanical stability and provide a path for incorporating polymers with desired properties into one strong network. Promising fabrication methods, like electrospinning and additive manufacturing, allow scientists to customize designs for each application and reach the maximum potential for the system. In the near future, it is desired to fabricate biohybrid conducting polymer‐based interfaces loaded with cells, giving the opportunity for simultaneous stimulation and regeneration. Developing multi‐modal BMIs, Using artificial intelligence and machine learning to design advanced materials are among the future goals for this field. This article is categorized under: Therapeutic Approaches and Drug Discovery Nanomedicine for Neurological Disease
Publisher: Elsevier BV
Date: 06-2022
Publisher: Wiley
Date: 07-10-2013
DOI: 10.1002/JBM.B.33034
Abstract: Various bioactive glass/hydroxyapatite (HA) functional coatings were designed by the suspension plasma spraying (SPS) technique. Their microstructure, scratch resistance, and apatite-forming ability in a simulated body fluid (SBF) were compared. The functional coatings design included: (i) composite coating, that is, randomly distributed constituent phases (ii) duplex coating with glass top layer onto HA layer and (iii) graded coating with a gradual changing composition starting from pure HA at the interface with the metal substrate up to pure glass on the surface. The SPS was a suitable coating technique to produce all the coating designs. The SBF tests revealed that the presence of a pure glass layer on the working surface significantly improved the reactivity of the duplex and graded coatings, but the duplex coating suffered a relatively low scratch resistance because of residual stresses. The graded coating therefore provided the best compromise between mechanical reliability and apatite-forming ability in SBF. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 102B: 551-560, 2014.
Publisher: Elsevier BV
Date: 02-2014
Publisher: Elsevier BV
Date: 12-2009
Publisher: Elsevier BV
Date: 06-2015
DOI: 10.1016/J.MSEC.2015.02.041
Abstract: Bioactive glass/hydroxyapatite composites for bone tissue repair and regeneration have been produced and discussed. The use of a recently developed glass, namely BG_Ca/Mix, with its low tendency to crystallize, allowed one to sinter the s les at a relatively low temperature thus avoiding several adverse effects usually reported in the literature, such as extensive crystallization of the glassy phase, hydroxyapatite (HA) decomposition and reaction between HA and glass. The mechanical properties of the composites with 80wt.% BG_Ca/Mix and 20wt.% HA are sensibly higher than those of Bioglass® 45S5 reference s les due to the presence of HA (mechanically stronger than the 45S5 glass) and to the thermal behaviour of the BG_Ca/Mix, which is able to favour the sintering process of the composites. Biocompatibility tests, performed with murine fibroblasts BALB/3T3 and osteocites MLO-Y4 throughout a multi-parametrical approach, allow one to look with optimism to the produced composites, since both the s les themselves and their extracts do not induce negative effects in cell viability and do not cause inhibition in cell growth.
Publisher: Springer Science and Business Media LLC
Date: 30-09-2017
DOI: 10.1007/S00253-017-8539-3
Abstract: Bacterial cellulose is composed of an ultrafine nanofiber network and well-ordered structure therefore, it offers several advantages when used as native polymer or in composite systems.In this study, a pool of 34 acetic acid bacteria strains belonging to Komagataeibacter xylinus were screened for their ability to produce bacterial cellulose. Bacterial cellulose layers of different thickness were observed for all the culture strains. A high-producing strain, which secreted more than 23 g/L of bacterial cellulose on the isolation broth during 10 days of static cultivation, was selected and tested in optimized culture conditions. In static conditions, the increase of cellulose yield and the reduction of by-products such as gluconic acid were observed. Dried bacterial cellulose obtained in the optimized broth was characterized to determine its microstructural, thermal, and mechanical properties. All the findings of this study support the use of bacterial cellulose produced by the selected strain for biomedical and food applications.
Publisher: Elsevier
Date: 2022
Publisher: Elsevier BV
Date: 06-2014
Publisher: Wiley
Date: 16-06-2023
Abstract: As additive manufacturing (AM), particularly metal and polymer‐based 3D printing, progresses from a scientific curiosity to an industry mainstay, there is an increasing desire for parts to take on secondary roles beyond their primary, typically structural or mechanical, function. This may enable unique and broad‐ranging functional customization, including monitoring part performance or its local environment, provisions for unique identifiers in tracking, anticounterfeiting, quality control, and even product certification. Many materials and processing compatibility requirements must be addressed to achieve embedded function, as embedded fillers or additives must not compromise either the part's production or its primary function. Herein, the material, technological, and processing challenges are highlighted for embedding function into parts produced by some of the most popular AM techniques, with ex les provided from the literature. While it is possible to produce cavities within 3D printed parts and place functional components within them postbuild, approaches, herein, specifically explore direct incorporation of functional agents, fillers, and additives during the build process that imparts ancillary function. It is hoped to inspire exploration of the possibilities and enhancements achievable through functional AM. On account of its versatility, binder jetting is analyzed as a case study, with novel approaches for embedding new functions outlined.
Publisher: Wiley
Date: 29-08-2013
DOI: 10.1002/JBM.A.34918
Abstract: Highly porous scaffolds with composition similar to those of 45S5 and 58S bioglasses were successfully produced by an innovative processing method based on preceramic polymers containing micro- and nano-sized fillers. Silica from the decomposition of the silicone resins reacted with the oxides deriving from the fillers, yielding glass ceramic components after heating at 1000°C. Despite the limited mechanical strength, the obtained s les possessed suitable porous architecture and promising biocompatibility and bioactivity characteristics, as testified by preliminary in vitro tests.
Publisher: Elsevier
Date: 2020
Publisher: Elsevier BV
Date: 09-2008
Publisher: Elsevier BV
Date: 10-2018
Publisher: Elsevier BV
Date: 06-2010
Publisher: Elsevier BV
Date: 06-2011
Publisher: Elsevier BV
Date: 2006
Publisher: Elsevier BV
Date: 07-2023
Publisher: Elsevier BV
Date: 12-2013
Publisher: Springer Science and Business Media LLC
Date: 05-2009
Publisher: MDPI AG
Date: 04-01-2022
Abstract: Cement and lime currently are the most common binders in building materials. However, alternative materials and methods are needed to overcome the functional limitations and environmental footprint of conventional products. This Special Issue is entirely dedicated to “New frontiers in cementitious and lime-based materials and composites” and gathers selected reviews and experimental articles that showcase the most recent trends in this multidisciplinary field. Authoritative contributions from all around the world provide important insights into all areas of research related to cementitious and lime-based materials and composites, spanning from structural engineering to geotechnics, including materials science and processing technology. This topical cross-disciplinary collection is intended to foster innovation and help researchers and developers to identify new solutions for a more sustainable and functional built environment.
Publisher: Wiley
Date: 02-11-2011
DOI: 10.1002/JBM.A.33276
Abstract: Because of their excellent bioactivity, bioactive glasses are increasingly diffused to produce biomedical devices for bone prostheses, to face the dysfunctions that may be caused by traumatic events, diseases, or even natural aging. However, several processing routes, such as the production of scaffolds or the deposition of coatings, include a thermal treatment to apply or sinter the glass. The exposure to high temperature may induce a devetrification phenomenon, altering the properties and, in particular, the bioactivity of the glass. The present contribution offers an overview of the thermal behavior and properties of two glasses belonging to the Na2O-CaO-P2O5-SiO2 system, to be compared to the standard 45S5 Bioglass(®). The basic goal is to understand the effect of both the original composition and the thermal treatment on the performance of the sintered glasses. The new glasses, the one (BG_Na) with a high content of Na2O, the other (BG_Ca) with a high content of CaO, were fully characterized and sintering tests were performed to define the most interesting firing cycles. The sintered s les, treated at 880°C and 800°C respectively, were investigated from a microstructural point of view and their mechanical properties were compared to those of the bulk (not sintered) glass counterparts. The effect of sintering was especially striking on the BG_Ca material, whose Vickers hardness increased from 598.9 ± 46.7 HV to 1053.4 ± 35.0 HV. The in vitro tests confirmed the ability of the glasses, both in bulk and sintered form, of generating a hydroxyapatite surface layer when immersed in a simulated body fluid. More accurate biological tests performed on the sintered glasses proved the high bioactivity of the CaO-rich composition even after a heat treatment.
Publisher: Elsevier
Date: 2022
Publisher: Elsevier BV
Date: 07-2010
Publisher: Elsevier BV
Date: 03-2017
DOI: 10.1016/J.MSEC.2016.11.110
Abstract: The composition of a CaO-rich silicate bioglass (BG_Ca-Mix, in mol%: 2.3 Na
Publisher: Springer Science and Business Media LLC
Date: 07-09-2011
Publisher: Elsevier BV
Date: 04-2008
Publisher: Elsevier BV
Date: 03-2019
DOI: 10.1016/J.MSEC.2018.10.086
Abstract: The need for new approaches to investigate ex vivo the causes and effects of tumor and to achieve improved cancer treatments and medical therapies is particularly urgent for malignant pathologies such as lymphomas and leukemias, whose tissue initiator cells interact with the stroma creating a three-dimensional (3D) protective environment that conventional mono- and bi-dimensional (2D) models are not able to simulate realistically. The solvent-casting particulate leaching (SCPL) technique, that is already a standard method to produce polymer-based scaffolds for bone tissue repair, is proposed here to fabricate innovative 3D porous structures to mimic the bone marrow niche in vitro. Two different polymers, namely a rigid polymethyl methacrylate (PMMA) and a flexible polyurethane (PU), were evaluated to the purpose, whereas NaCl, in the form of common salt table, resulted to be an efficient porogen. The adoption of an appropriate polymer-to-salt ratio, experimentally defined as 1:4 for both PMMA and PU, gave place to a rich and interconnected porosity, ranging between 82.1 vol% and 91.3 vol%, and the choice of admixing fine-grained or coarse-grained salt powders allowed to control the final pore size. The mechanical properties under compression load were affected both by the polymer matrix and by the scaffold's architecture, with values of the elastic modulus indicatively varying between 29 kPa and 1283 kPa. Preliminary tests performed with human stromal HS-5 cells co-cultured with leukemic cells allowed us to conclude that stromal cells grown associated to the supports keep their well-known protective and pro-survival effect on cancer cells, indicating that these devices can be very useful to mimic the bone marrow microenvironment and therefore to assess the efficacy of novel therapies in pre-clinical studies.
Publisher: MDPI AG
Date: 29-11-2019
DOI: 10.3390/MET9121284
Abstract: Laser-based powder bed fusion (L-PBF) is an additive manufacturing (AM) technique that uses a computer-controlled laser beam as the energy source to consolidate a metal powder according to a layer-upon-layer strategy in order to manufacture a three dimensional part. This opens the way for an unprecedented freedom in geometry, but the layer-wise build-up strategy typically results in a very poor surface finish, which is affected by the staircase effect and by the presence of partially molten particles. Surface finishing treatments are therefore necessary to obtain an adequate surface finish, to improve the fatigue behavior and to meet mechanical and aesthetic needs. The present contribution systematically compares numerous surface finishing techniques, including laser shock processing, plastic media blasting, sand blasting, ceramic shot peening and metal shot peening with steel particles of different sizes (ϕ = 0.2 mm and ϕ = 0.4 mm). The results show that all the proposed methods improve the surface quality and the fatigue life of A357.0 L-PBF parts. However, the achievement of the lowest surface roughness does not necessarily correspond to the best fatigue performance, thus suggesting that multiple mechanisms may be active and that besides surface roughness also residual stresses contribute to increase the fatigue strength.
Publisher: Wiley
Date: 10-2022
Publisher: Elsevier BV
Date: 12-2009
Publisher: Elsevier BV
Date: 03-2020
Publisher: Elsevier BV
Date: 12-2015
Publisher: Elsevier BV
Date: 09-2014
DOI: 10.1016/J.MSEC.2014.05.047
Abstract: Presently, there is an increasing interest towards the composites of calcium phosphates, especially β-tricalcium phosphate (TCP), and bioactive glasses. In the present contribution, the recently developed BG_Ca/Mix glass has been used because its low tendency to crystallize allows to sinter the composites at relatively low temperature (i.e. 850°C), thus minimizing the glass devitrification and the interaction with TCP. A further improvement is the introduction of lab-produced TCP powders doped with specific ions instead of non-doped commercial powders, since the biological properties of materials for bone replacement can be modulated by doping them with certain metallic ions, such as Mg and Sr. Therefore, novel binary composites have been produced by sintering the BG_Ca/Mix glass with the addition of pure, Mg-substituted, Sr-substituted or Mg/Sr bisubstituted TCP powders. After an accurate characterization of the starting TCP powders and of the obtained s les, the composites have been used as three-dimensional supports for the culture of mouse calvaria-derived pre-osteoblastic cells. The s les supported cell adhesion and proliferation and induced promising mechanisms of differentiation towards an osteoblastic phenotype. In particular, the Mg/Sr bi-doped s les seemed to better promote the differentiation process thus suggesting a combined stimulatory effect of Mg(2+) and Sr(2+) ions.
Publisher: Elsevier BV
Date: 10-2014
DOI: 10.1016/J.MSEC.2014.07.037
Abstract: A new sol-gel (SG) method is proposed to produce special bioactive glasses (BG_Ca family) characterized by a low tendency to devitrify. These formulations, derived from 45S5 Bioglass®, are characterized by a high content of CaO (45.6 mol%) and by a partial or complete substitution of sodium oxide with potassium oxide (total amount of alkaline oxides: 4.6 mol%), which increases the crystallization temperature up to 900°C. In this way, it is possible to produce them by SG preserving their amorphous nature, in spite of the calcination at 850°C. The sintering behavior of the obtained SG powders is thoroughly investigated and the properties of the sintered bodies are compared to those of the melt-derived (M) counterparts. Furthermore, the SG glass powders are successfully used to produce scaffolds by means of a modified replication technique based on the combined use of polyurethane sponges and polyethylene particles. Finally, in the view of a potential application for bone tissue engineering, the cytotoxicity of the produced materials is evaluated in vitro.
Publisher: Wiley
Date: 23-12-2015
DOI: 10.1002/JBM.A.35619
Abstract: Calcium phosphates are among the most common biomaterials employed in orthopaedic and dental surgery. The efficacy of such systems as bone substitutes and bioactive coatings on metallic prostheses has been proved by several clinical studies. Among these materials, hydroxyapatite (HA) and tricalcium phosphate (TCP) play a prominent role in medical practice since the '80s. In the last years, numerous attempts to combine HA or TCP with bioactive glasses have been made. There are two main motivations for sintering calcium phosphates with a glassy phase: on the one hand, it is possible to tune the dissolution of the final system and to enhance its biological response through the synergistic combination of two bioactive phases on the other hand, the glass acts as a sintering aid with the aim to increase the densification of the composite and thus its mechanical strength. In this sense, TCP and HA are penalized by their relatively poor fracture toughness and tensile strength compared to natural bone, which makes it impossible to use them in load-bearing applications. Moreover, the bioactivity index of pure calcium phosphates is typically lower with respect to that of many bioactive glasses. In this review, the state of the art and current applications of composites, based on HA or TCP with bioactive glass as second phase, are presented and discussed. A special emphasis is given to the processing and mechanical behaviour of these systems, together with their biological implications, as a function of the composition of the glass employed as second phase.
Location: Australia
No related grants have been discovered for Antonella Sola.