ORCID Profile
0000-0001-6390-6852
Current Organisation
The University of Auckland
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Publisher: Royal Society of Chemistry (RSC)
Date: 2021
DOI: 10.1039/D1SE00993A
Abstract: A 3D porous carbon framework embedded with uniform Ag nanoparticles (ADPCF) is fabricated by a one-step chemical blowing process. The ADPCF electrode exhibits great cycling stability for over 2500 h (1250 cycles) with small hysteresis.
Publisher: Trans Tech Publications, Ltd.
Date: 04-2009
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.618-619.501
Abstract: The present study aims to develop a process to make ultrafine grained (UFG) Ti-47Al-2Cr (at %) alloy using elemental Ti, Al and Cr powders. The process involves mechanical milling of a mixture of the elemental powders to produce a Ti/Al/Cr composite powder, compaction of the milled powder, and consolidation of the powder compact using hot isostatic pressing (HIP) or powder compact forging. This paper is to give an overview of microstructure and the mechanical properties of the alloy s les obtained using the above processing technique. Inhomogeneous microstructures with high amounts of (α2) Ti3Al phase, along with, elemental Ti, were observed in some s les. An attempt has been made to explain the formation of (α2) Ti3Al, and elemental Ti, in the alloy and the processing conditions appropriate for the specific alloy are also discussed.
Publisher: Elsevier BV
Date: 08-2018
Publisher: Royal Society of Chemistry (RSC)
Date: 2016
DOI: 10.1039/C6RA23944G
Abstract: The electrocatalytic efficiency of electrodeposited (ED) Ni–W alloy coatings for the hydrogen evolution reaction (HER) has been improved drastically through magnetoelectrodeposition (MED) approach.
Publisher: Elsevier BV
Date: 09-2023
Publisher: Elsevier BV
Date: 10-2004
Publisher: Springer Science and Business Media LLC
Date: 15-06-2010
Publisher: MDPI AG
Date: 03-03-2017
DOI: 10.3390/MET7030081
Publisher: MDPI AG
Date: 03-04-2015
DOI: 10.3390/MET5020530
Publisher: World Scientific Pub Co Pte Lt
Date: 30-10-2006
DOI: 10.1142/S0217979206040441
Abstract: The grain growth kinetics of nanocrystalline copper thin film s les was investigated. The grain size of nanocrystalline copper s les was determined from the broadening of X-ray spectra. It was found that the grain size increased linearly with isothermal annealing time within the first 10 minutes, beyond which power-law growth kinetics is applied. The activation energy for grain growth was determined by constructing an Arrhenius plot, which shows an activation energy of about 21 – 30 kJ/mol. The low activation energy is attributed to the second phase particle drag and the porosity drag, which act as the pinning force for grain growth in nanocrystalline copper.
Publisher: Elsevier BV
Date: 05-2018
Publisher: Elsevier BV
Date: 11-2019
Publisher: Maney Publishing
Date: 06-2007
Publisher: Elsevier BV
Date: 2014
Publisher: Elsevier BV
Date: 12-2022
Publisher: Trans Tech Publications, Ltd.
Date: 08-2012
DOI: 10.4028/WWW.SCIENTIFIC.NET/KEM.520.76
Abstract: This paper reports the synthesis of porous titanium with a nominal composition of Ti-6 wt%Al-4wt%V through a press-and-sinter process. Blended elemental (BE) mixtures of Ti and master alloy Al-40V powders were uniaxially pressed and sintered in vacuum. Porosity of the sintered s les was determined in the range of 23vol. % to 37vol. % by the Archimedes method. Tensile strengths were found to range from 73 to 147MPa and Young’s moduli of the sintered s les varied from 3.4GPa to 13GPa. Both tensile strength and elastic modulus decreased with increasing porosity. Electrochemical assessment of the sintered porous s les showed deteriorated corrosion resistance, as compared to 95% dense Ti-6Al-4V prepared by sintering pre-alloyed powder. The challenge of using blended elemental powder sintering to fabricate porous Ti-6Al-4V alloys is discussed.
Publisher: Elsevier BV
Date: 02-2017
Publisher: MDPI AG
Date: 06-06-2018
DOI: 10.20944/PREPRINTS201806.0074.V1
Abstract: In this study, a 5vol. % (TiBw+TiCp)/Ti composite pancake with a diameter of 260mm was prepared by casting followed by open die forging in (& alpha +& beta ) phase region. The microstructures of the composite pancake are inhomogeneous, in terms of both matrix microstructure and distribution of reinforcements. The matrix microstructures were gradually refined from the periphery to centre of the pancake. The TiBw and TiCp reinforcements tend to be uniformly distributed in the centre region and. It is suggested that the microstructure difference can be mainly ascribed to the temperature variation from the periphery to the centre. Additionally, tensile testing results showed that the centre region of the composite pancake exhibits higher strength than the peripheral region. The strengthening mechanism and the softening behavior of the composite pancake with temperature is discussed.
Publisher: Elsevier BV
Date: 10-2023
Publisher: Elsevier BV
Date: 09-2019
Publisher: Elsevier BV
Date: 05-2014
Publisher: Elsevier BV
Date: 03-2001
Publisher: Elsevier BV
Date: 11-2021
Publisher: Center for Open Science
Date: 05-2022
Abstract: Technological advances in psychological research have enabled large-scale studies of human behavior and streamlined pipelines for automatic processing of data. However, studies of infants and children have not fully reaped these benefits, because the behaviors of interest, such as gaze duration and direction, even when collected online, still have to be extracted from video through a laborious process of manual annotation. Recent advances in computer vision raise the possibility of automated annotation of this video data. In this paper, we built on a system for automatic gaze annotation in young children, iCatcher (Erel et al., 2022), by engineering improvements, and then training and testing the system (hereafter, iCatcher+) on three datasets with substantial video and participant variability (214 videos collected in United States lab and field sites, 143 videos collected in Senegal field sites, and 265 videos collected via webcams in homes participants aged 4 months-3.5 years). When trained on each of these datasets, iCatcher+ performed with near human-level accuracy on held-out videos on distinguishing “LEFT” versus “RIGHT”, and “ON” versus “OFF” looking behavior, across all datasets. This high performance was achieved at the level of in idual frames, experimental trials, and study videos, held across participant demographics (e.g., age, race/ethnicity), participant behavior (e.g., movement, head position) and video characteristics (e.g., luminance), and generalized to a fourth, entirely held-out online dataset. We close by discussing next steps required to fully automate the lifecycle of online infant and child behavioral studies, representing a key step towards enabling rapid, high-powered developmental research.
Publisher: Wiley
Date: 16-02-2018
DOI: 10.1111/JACE.15478
Publisher: Trans Tech Publications, Ltd.
Date: 04-2009
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.618-619.513
Abstract: Consolidation of titanium and titanium alloy powders using thermomechanical powder metallurgy (TPM) processes (powder compact forging, extrusion and rolling) is one way that can lead to cost-effective production of high value-added consolidated titanium and titanium alloy products such as near-net shaped components, tubes and plates. This paper provides an overview of the quality, microstructure (to limited depth), porosity level and mechanical properties of disks produced using open die forging of powder compacts of CP titanium and Ti-6Al-4V alloy powders. The general materials science principles underlying the relationships between processing conditions, microstructure and the mechanical properties of the disks made by using the powder compact forging are discussed.
Publisher: American Chemical Society (ACS)
Date: 10-01-2022
DOI: 10.1021/ACS.INORGCHEM.1C03470
Abstract: Rb
Publisher: Elsevier BV
Date: 05-2022
Publisher: Elsevier BV
Date: 06-2013
Publisher: The Electrochemical Society
Date: 2014
DOI: 10.1149/2.032406JES
Publisher: IOP Publishing
Date: 08-2009
Publisher: Elsevier BV
Date: 04-2007
Publisher: Elsevier BV
Date: 09-2018
Publisher: Informa UK Limited
Date: 07-08-2016
Publisher: Elsevier BV
Date: 06-2006
Publisher: World Scientific Pub Co Pte Lt
Date: 30-10-2006
DOI: 10.1142/S0217979206041884
Abstract: The motivation of this research is to develop a process for producing Ti/Al composite powders that enable synthesis of a single-phase TiAl intermetallic bulk material, which is then used as a target for physical vapour deposition (PVD) coating. This study reports the effects of milling time, amount of process control agent (PCA) added as well as the powder-to-medium ratio on the microstructure of the Ti/Al composite powder. Optical microscopy and scanning electron microscopy (SEM) were used to evaluate the level of mixing and the resulting powder particle size. X-ray diffraction analysis and differential thermal analysis were used for determining the phase constituents and the solid state reaction temperature of the as-milled powders.
Publisher: Elsevier BV
Date: 03-2018
Publisher: Informa UK Limited
Date: 04-2015
Publisher: Elsevier BV
Date: 11-2018
Publisher: Elsevier BV
Date: 03-2005
Publisher: Elsevier BV
Date: 08-2014
Publisher: The Electrochemical Society
Date: 2018
DOI: 10.1149/2.0161814JES
Publisher: Elsevier BV
Date: 08-2011
Publisher: Springer Science and Business Media LLC
Date: 16-07-2012
Publisher: Informa UK Limited
Date: 29-03-2023
Publisher: Springer Science and Business Media LLC
Date: 23-10-2013
Publisher: American Chemical Society (ACS)
Date: 02-08-2023
Publisher: Springer Science and Business Media LLC
Date: 30-10-2013
Publisher: Royal Society of Chemistry (RSC)
Date: 2013
DOI: 10.1039/C3CE41184B
Publisher: Trans Tech Publications, Ltd.
Date: 06-2011
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.690.206
Abstract: The Interdependence Theory is a theoretical description of grain formation that links heterogeneous nucleation to grain growth early in the initial transient of a previously nucleated grain. Thus nucleation is the result of a repeating cycle of growth and nucleation events moving towards the thermal centre of a casting. The principles of this theory are introduced and then the Interdependence equation that embodies the Interdependence Theory, is applied to the prediction of experimental grain size data for aluminium, magnesium and titanium-based alloy systems.
Publisher: Elsevier BV
Date: 12-2003
Publisher: Elsevier BV
Date: 05-2007
Publisher: Royal Society of Chemistry (RSC)
Date: 2023
DOI: 10.1039/D3QI00180F
Abstract: The aliovalent doping of Ce 3+ /K + in α′-Sr 2 SiO 4 leads to a thermally enhanced phosphor with bright blue emission, and electron traps modulated by defect engineering contribute to an abnormal thermal quenching phenomenon.
Publisher: MDPI AG
Date: 26-07-2017
DOI: 10.3390/MET7080285
Publisher: Informa UK Limited
Date: 06-06-2018
Publisher: Trans Tech Publications, Ltd.
Date: 08-2012
DOI: 10.4028/WWW.SCIENTIFIC.NET/KEM.520.139
Abstract: This work aims to study sintering of elemental titanium and pre-alloyed Ti-6Al-4V powders in a graphite furnace which is operated with back-filled argon. The specific task is to investigate the effect of carbon, oxygen and nitrogen contamination in the furnace atmosphere during sintering. X-ray diffraction (XRD) reveals that the main phase on the surface of the sintered s les was a titanium oxycarbonitride – Ti(CNO). The surface of all s les was porous due to the reaction between titanium and contaminants. A close-up surface morphological observation with environmental scanning electron microscopy (ESEM) shows the presence of spherical particles in the sintered Ti specimens, but not observed in the Ti-6Al-4V alloy specimens. Energy dispersive spectrometry (EDS) results indicate that these spheres mainly contain carbon and titanium. It is postulated that residual chlorine (Cl), a common impurity for sponge Ti powder but not for pre-alloyed Ti-6Al-4V powder, may play an important role in the formation of these spheres. Microhardness is dependent on the contaminant content on the s le surface. The implication of using graphite furnaces for sintering is discussed.
Publisher: Elsevier BV
Date: 11-2022
Publisher: American Chemical Society (ACS)
Date: 27-06-2023
Publisher: Informa UK Limited
Date: 05-2004
Publisher: MDPI AG
Date: 25-06-2018
DOI: 10.3390/MET8070485
Publisher: Springer Science and Business Media LLC
Date: 05-01-2017
DOI: 10.1557/JMR.2016.506
Publisher: American Chemical Society (ACS)
Date: 30-01-2023
Publisher: Trans Tech Publications, Ltd.
Date: 07-05-2014
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.922.657
Abstract: In this study, hydroxyapatite (HA) coatings on Ti6Al4V substrate were deposited using an ion beam sputtering technique. Owing to its medical applications, the crystalline phases present in the HA must be controlled. This study investigated the effect of post-deposition heat treatment at different temperatures and evaluated the microstructure of the HA coatings and their behaviours in simulated body fluid (SBF). The post-deposition treatment of the as-deposited s les was carried out in an air-circulated furnace at a temperature between 300 0 C and 600 0 C. The XRD patterns reveal that the minimum temperature to transform the HA coating from amorphous to crystalline phase is 400 0 C. A higher temperature at 600 0 C leads to a growth of the crystalline HA phases. Fourier transform infrared spectroscopy (FTIR) measurements show the existence of hydroxyl and PO-bonds in all coatings and the amounts varied with temperature. Atomic Force Microscopy (AFM) study suggests that the nanostructured crystalline HA starts to grow at 400 0 C and becomes more obvious at a higher temperature of 600 0 C. The simulated body fluid (SBF) test reveals that better apatite formation with post deposition heat treatment at 600 0 C would potentially enhance the formation of new bone (osseointegration).
Publisher: Wiley
Date: 03-10-2011
DOI: 10.1002/JBM.A.33239
Abstract: This study investigated the surface characteristics and in vitro cytocompatibility of hierarchical textured titanium surfaces with nanograins and microroughness, produced by surface mechanical attrition treatment (SMAT). The surface characteristics were evaluated by scanning electron microscopy, X-ray diffraction, transmission electron microscopy, contact angle, and surface energy measurements. The in vitro cytocompatibility of the SMAT processed surfaces (hereafter Ti-SMAT surfaces) were assessed in terms of cellular attachment, morphology, viability, alkaline phosphatase (ALP) activity, and mRNA gene expression. Two other titanium surfaces were compared: well-polished Ti6Al4V surfaces (hereafter Ti-polish surfaces) and thermally sprayed rough surfaces (hereafter Ti-spray surfaces). The Ti-SMAT surfaces showed a higher hydrophilicity and increased surface energy compared with the Ti-polish and Ti-spray surfaces. Consequently, these Ti-SMAT surfaces demonstrated enhancement of cell attachment, spreading, viability, and ALP activity. Reverse transcriptase polymerase chain reaction (RT-PCR) analysis showed significantly higher ALP activity and stronger expression of mRNA levels of key osteoblast genes in cells grown on the Ti-SMAT surfaces than the other two surfaces. These results reveal a synergic role played by nanostructure and microtopography in osteoblastic functions and demonstrate the more promising cytocompatibility of the hierarchical textured surfaces. It is suggested that the SMAT process may provide a novel method of surface modification to the currently available metallic biomaterials.
Publisher: World Scientific Pub Co Pte Lt
Date: 23-04-2015
Publisher: Elsevier BV
Date: 10-2015
Publisher: Elsevier BV
Date: 08-2019
Publisher: Elsevier BV
Date: 04-2015
Publisher: Elsevier BV
Date: 04-2014
Publisher: Inderscience Publishers
Date: 2014
Publisher: Royal Society of Chemistry (RSC)
Date: 2022
DOI: 10.1039/D2NR01110G
Abstract: Potassium-ion capacitors (PICs) have drawn appreciable attention because PICs can masterly integrate the virtues of the high energy density of battery-type anode and high power density of capacitor-type cathode. However, the sanguine scenario involves the incompatible capacity and sluggish kinetics in the PIC device. Herein, we report the synthesis of nitrogen and phosphorus-doped network porous carbon materials (NPMCs)
Publisher: Trans Tech Publications, Ltd.
Date: 04-2009
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.618-619.307
Abstract: With their very low density, excellent biocompatibility, and good mechanochemical properties, titanium alloys have been considered a high-end material for making biomedical devices and instruments. However, they still have some substantial challenges to be overcome. One major problem, which eventually leads to revision surgery, is the implant loosening- a result of tissue migration, formation of wear debris, insufficient interface bonding between bone and implant, and stress shielding. Nanosized features in the material have the potential to provide a solution to these problems. A nanostructured surface is able to not only promote tissue ingrowth, but also increase the surface hardness and therefore improving the wear resistance and enhancing fatigue strength. This paper reports our recent work on how surface treatment on titanium alloys changes their mechanical properties. The mechanism by which the surface nanostructuring alters mechanical properties has also been discussed.
Publisher: Elsevier BV
Date: 06-2019
Publisher: Elsevier BV
Date: 03-2018
Publisher: Elsevier BV
Date: 02-2023
Publisher: Elsevier BV
Date: 06-2017
Publisher: Elsevier BV
Date: 12-2015
Publisher: Springer Science and Business Media LLC
Date: 16-03-2017
Publisher: Trans Tech Publications, Ltd.
Date: 07-2011
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.275.186
Abstract: Powder compact forging was used to produce bulk consolidated titanium and Ti-6Al-4V (wt %) and Ti-47Al-2Cr (at%) alloy disks from hydrogenated and dehydrogenated (HDH) and gas atomised powders (GA) powders (in the case of titanium and Ti-6Al-4V) and a mechanically milled powder (in the case of Ti-47Al-2Cr alloy). The bulk titanium and Ti-6Al-4V (wt %) alloy have been produced by forging of the powder compacts. The Ti-47Al-2Cr (at %) alloy was produced using canned powder compact forging of a Ti/Al/Cr composite powder. The purpose of the present study is to investigate the deformation and fracture behaviour of the bulk consolidated as-forged materials, by conducting tensile testing at room temperature (RT) and examination of the fractured specimens which had near-α, α + β and phase structures, respectively. It was found that as-forged bulk titanium disk produced using HDH powder showed a yield point with a yield strength of ~700 MPa and with a considerable amount of ductility. While the as-forged Ti-6Al-4V (wt %) alloy produced using HDH powder, fractured prematurely without any yielding. On the other hand yielding was observed in the as-forged Ti-6Al-4V (wt %) alloy produced using GA powder, showing a yield strength of ~970 MPa and a considerable amount of plastic strain to fracture. The bulk consolidated Ti-47Al-2Cr (at %) alloy also fractured prematurely with fracture strength of ~125 MPa. The mechanical behaviour of the as-forged bulk materials was found to be dependent on several factors such as initial powders used, green density of the powder compact, forging parameters used during forging. It was expected that the entrapped gas in green compacts, absorbed oxygen, porosity and inter-particle bonding play an important role on the quality of the as-forged material, which in turn affected the mechanical behaviour of the bulk material.
Publisher: Springer Science and Business Media LLC
Date: 24-07-2013
Publisher: Springer Science and Business Media LLC
Date: 07-2005
Publisher: Elsevier BV
Date: 09-2014
Publisher: MDPI AG
Date: 09-02-2017
DOI: 10.20944/PREPRINTS201702.0028.V1
Abstract: This work investigated the isothermal holding time dependence of the densification, microstructure, weight loss and tensile properties of Fe-Mn-Si powder compacts. Elemental Fe, Mn and Si powder mixtures with a nominal composition of Fe-28Mn-3Si (in weight percent) were ball milled for 5h and subsequently pressed under a uniaxial pressure of 400 MPa. The compacted Fe-Mn-Si powder mixtures were sintered at 1200 ℃ for 0, 1, 2 and 3 h, respectively. In general, the density, weight loss and tensile properties increased with the increase of isothermal holding time. A significant increase in density, weight loss and tensile properties occurred in the compacts isothermally holding for 1 h, as compared to those with no isothermal holding. However, further extension of isothermal holding time (2 and 3 h) only played a limited role in promoting the density and tensile properties. The weight loss of the sintered compacts was mianly caused by the sublimation of Mn in Mn depletion region on the surface layer of the sintered Fe-Mn-Si compacts. The length of the Mn depletion region increased as isothermal holding time increased. A single & alpha -Fe phase was detected on the surface of all the sintered compacts, and the locations beyond the Mn depletion region were comprised of a dual dominant & gamma -austenite and minor & epsilon -martensite.
Publisher: Science Alert
Date: 11-2014
Publisher: World Scientific Pub Co Pte Lt
Date: 25-07-2013
DOI: 10.1142/S0217984913410121
Abstract: In this paper, Nitinol, an equiatomic binary alloy of nickel and titanium, was surface modified for its potential biomedical applications by chemical and electrochemical etching. The main objective of the surface modification is to reduce the nickel content on the surface of Nitinol and simultaneously to a rough surface microstructure. As a result, better biocompatibility and better cell attachment would be achieved. The effect of the etching parameters was investigated, using scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectrometry (EDX) and X-ray photoelectron spectrometry (XPS). The corrosion property of modified Nitinol surfaces was investigated by electrochemical work station. After etching, the Ni content in the surface layer has been reduced and the oxidation of Ti has been enhanced.
Publisher: Springer Science and Business Media LLC
Date: 23-04-2015
Publisher: American Chemical Society (ACS)
Date: 28-08-2014
DOI: 10.1021/CG500841X
Publisher: Elsevier BV
Date: 05-2010
Publisher: Elsevier BV
Date: 2019
Publisher: Elsevier BV
Date: 07-2020
Publisher: Elsevier BV
Date: 10-2013
Publisher: Wiley
Date: 28-02-2017
Abstract: Aluminum-nitrogen six-fold octahedral coordination, [AlN
Publisher: World Scientific Pub Co Pte Lt
Date: 23-04-2015
DOI: 10.1142/S0217979215400172
Abstract: The precipitation process discussed in the present study involves the addition of alkaline solutions to an acidic calcium phosphate suspension. Several parameters (pH, pH buffer reagent, ageing and stirring) were investigated. The synthesized powders were calcined at 1000°C for 1 h in air, in order to study the thermal stability and crystalline phase compositions. X-ray diffraction (XRD) and ESEM analysis were used for s le characterization. It is found that all these processing parameters affect the crystalline phases evolved and resultant microstructures. Phase evolution occurred at an elevated pH level. The pH buffer reagent would affect both the phase composition and microstructure. Ageing was essential for the phase maturation. Stirring accelerated the reaction process by providing a homogeneous medium for precipitation.
Publisher: Informa UK Limited
Date: 09-2011
Publisher: Wiley
Date: 09-2007
Publisher: MDPI AG
Date: 22-08-2022
DOI: 10.3390/IJMS23169495
Abstract: Compared to the equiatomic or near-equiatomic NiTinol alloys, Ni-rich NiTi alloys are suitable to be employed in structural applications as they exhibit higher hardness and are dimensionally stable. This research aimed to process two different grades of Ni-rich NiTi alloys, 58NiTi and 60NiTi, from Ni–Ti powder mixtures having about 58 wt.% and 60 wt.% Ni, respectively. This was performed by a laser powder bed fusion technique. At the first stage of this research, the printability of the used powder mixtures was investigated by applying different sets of printing parameters. Two appropriate sets were then selected to print the s les. Microstructural study of the printed parts revealed the existence of inhomogeneity in the microstructures. In addition, depending on the applied set of parameters, some amounts of cracks and pores were also present in the microstructure of these parts. Postprinting hot isostatic pressing procedures, performed at different temperatures, were developed to cause the reaction of phases, homogenize the parts, and possibly eliminate the existing flaws from the s les. Effects of these applied treatments on the microstructure, phase composition, density, dimensional integrity, and hardness of parts were sequentially studied. In essence, 58NiTi and 60NiTi parts having phase compositions complying with those of the equilibrium phase diagram were obtained in this research. However, the mentioned cracks and pores, formed in the microstructure of as-printed parts, could not be fully removed by postprocessing treatments.
Publisher: Springer Science and Business Media LLC
Date: 19-04-2018
Publisher: Elsevier BV
Date: 09-2015
Publisher: Elsevier BV
Date: 2018
Publisher: Elsevier BV
Date: 06-2023
Publisher: World Scientific Pub Co Pte Lt
Date: 23-04-2015
DOI: 10.1142/S0217979215400056
Abstract: Impurity control is crucial to Ti metal powder injection molding (Ti-MIM) since titanium is a universal solvent to interstitial elements such as oxygen, carbon and nitrogen. In this study, a low decomposition temperature binder system was developed the rheological and solvent debinding assessments of the feedstock formulated from this binder were performed. Solvent mixing was employed to prepare homogeneous feedstocks. Effects of powder shape and solid loading on rheological properties were evaluated. After injection molding, a debinding profile was constructed. The debound parts were then characterized by microstructural observation.
Publisher: MDPI AG
Date: 22-02-2017
DOI: 10.3390/MET7020067
Publisher: Elsevier BV
Date: 12-2023
Publisher: Elsevier BV
Date: 07-2023
Publisher: Elsevier BV
Date: 04-2022
Publisher: MDPI AG
Date: 04-03-2022
DOI: 10.3390/MET12030448
Abstract: The direct reduction of TiO2 to low-oxygen titanium metal is achievable via Hydrogen Assisted Magnesiothermic Reduction (HAMR). To investigate and leverage the oxygen-scavenging properties of rare-earth dopant species on the HAMR process, Y-doped and undoped TiO2 powders were synthesized and characterized. HAMR blends incorporating the synthesized TiO2 were reduced under forming gas atmospheres. X-ray powder diffraction (XRD) and scanning electron microscope (SEM) characterization was performed prior to and following reduction. The TiO2 powders were observed to be dense and nanocrystalline. Following reduction, more extensive development of intermediate HAMR phases was observed as a result of Y-doping. The microstructure hase evolution of the HAMR reduction phases was observed to deviate from the expected for dense TiO2 particles. Rapid restructuring of the TiO2 particle interiors was attributed to increased bulk diffusion rates of nanocrystalline materials. Doped nanocrystalline TiO2 powders were identified as potential alternative feedstocks for HAMR experiments. The byproduct MgO phase was observed to grow as a particle agglomerating network that is dense when formed at 750 °C and porous when formed at 900 °C.
Publisher: Elsevier BV
Date: 11-2022
Publisher: Elsevier BV
Date: 12-2021
Publisher: Elsevier BV
Date: 07-2011
Publisher: Elsevier BV
Date: 09-2019
Publisher: Elsevier BV
Date: 11-2001
Publisher: American Chemical Society (ACS)
Date: 14-08-2013
DOI: 10.1021/CG400835N
Publisher: Elsevier BV
Date: 2016
Publisher: American Association for the Advancement of Science (AAAS)
Date: 22-09-2023
Publisher: Wiley
Date: 28-02-2017
Publisher: Wiley
Date: 06-03-2017
Publisher: Elsevier BV
Date: 05-2013
Publisher: Springer Science and Business Media LLC
Date: 17-03-2015
DOI: 10.1038/SREP09159
Abstract: X-ray diffraction technique using a laboratory radiation has generally shown limitation in detectability. In this work, we investigated the in situ high-temperature crystallization of a lithium disilicate glass-ceramic in the SiO 2 –Li 2 O–CaO–P 2 O 5 –ZrO 2 system with the aid of synchrotron radiation. The formation of lithium metasilicate and other intermediate phases in trace amount was successfully observed by synchrotron X-ray diffraction (SXRD). The crystallization mechanism in this glass was thus intrinsically revised to be the co-nucleation of lithium metasilicate and disilicate, instead of the nucleation of lithium disilicate only. The phase content, crystallite size and crystallographic evolutions of Li 2 Si 2 O 5 in the glass-ceramic as a function of annealing temperature were studied by performing Rietveld refinements. It is found that the growth of Li 2 Si 2 O 5 is constrained by Li 2 SiO 3 phase at 580–700°C. The relationship between the crystallographic evolution and phase transition was discussed, suggesting a common phenomenon of structural response of Li 2 Si 2 O 5 along its c axis to other silicon-related phases during glass crystallization.
Publisher: World Scientific Pub Co Pte Lt
Date: 23-04-2015
DOI: 10.1142/S0217979215400147
Abstract: This work presents a comparative study of a series of Fe – Mn – Si alloys proposed as degradable biomaterials for medical applications. Five Fe -28wt.% Mn -x Si (where x = 0 to 8 wt.%) alloys were fabricated by an arc-melting method. All the as-cast alloys were subsequently subjected to homogenization treatment and hot forging. The microstructure and phase constituents were investigated. It is found that the grain size of the as-forged alloys ranged approximately from 30 to 50 μm. The as-forged Fe – Mn – Si alloys containing Si from 2 to 6 wt.% was comprised of duplex martensitic ε and austenitic γ phases however, the Si -free and 8 wt.% Si alloys only consisted of a single γ phase. After 30 days of static immersion test in a simulated body fluid (SBF) medium, it is found that pitting and general corrosion occur on the s le surfaces. Potentiodynamic analysis reveals that the degradation rate of the Fe – Mn – Si alloys increased gradually with Si content up to 6 wt.%, beyond which the degradation slows down.
Publisher: Trans Tech Publications, Ltd.
Date: 08-2012
DOI: 10.4028/WWW.SCIENTIFIC.NET/KEM.520.174
Abstract: A water soluble binder system is used to prepare Ti-6Al-4V and NiTi pre-alloyed powder feedstock. The binder dissolution and transport kinetics through the porous powder skeleton are studied for various powder morphologies and powder loadings from 60 to 69.5 vol.%. The binder removal behaviours are evaluated with different debinding time intervals. The focus of this work is to investigate the influences of shaping pressure, specimen thickness and water bath temperature on the binder extraction behaviour.
Publisher: Elsevier BV
Date: 03-2017
Publisher: Elsevier BV
Date: 09-2014
Publisher: American Chemical Society (ACS)
Date: 22-11-2013
DOI: 10.1021/IC402112Z
Abstract: In this work, the high-temperature crystallographic evolution of crystalline phases in a complex lithium disilicate glass was investigated using synchrotron X-ray powder diffraction. The lattice parameters and unit cell volume of Li2SiO3 (LS), Li2Si2O5 (LS2), Li3PO4 (LP), and ZrO2 as a function of temperature were determined upon heating. It is found that the lattice parameter c of LS2 shows a "V"-shaped trend during heating. The crystallographic evolution of the LS2 phase has a close correlation with the LS phase, indicating the mutual interaction between LS and LS2 phases along the c axis during the nucleation/crystallization process. The phase evolution processes were different upon heating and cooling, and the unit cell volume of both LS and LP phases demonstrated different change rates. In this glass system, no LS2 was detected during cooling and the main phases formed during cooling process were LP, LS, β-cristobalite, and β-quartz. Interestingly, there were two forms of β-quartz with slightly different lattice constants, and the silica phases showed a near-zero expansion behavior. The crystallographic evolution mechanism is discussed.
Publisher: Elsevier BV
Date: 02-2022
Publisher: Elsevier BV
Date: 12-2018
Publisher: World Scientific Pub Co Pte Ltd
Date: 06-2015
DOI: 10.1142/S1793604715400111
Abstract: In this paper, we report a series of homogeneous polymeric composites with enhanced dielectric properties and thermal conductivity. The composites were constituted of polyvinylidene fluorides (PVDFs) matrix and CaCu 3 Ti 4 O 12 (CCTO) monolithic or CCTO/β- SiC hybrid fillers, and prepared by simple melt blending and hot moulding technique. The influence of different types of fillers and their composition on the dielectric response and thermal conductivity of the obtained composites was studied. Results show that hybrid loading is preferred and a reasonable combination of thermal conductivity (0.80 W⋅m -1 ⋅K -1 ), dielectric constant (∼50) and dielectric loss (∼0.07) at 10 3 Hz was achieved in the PVDF composite containing 40 vol.% CCTO and 10 vol.% β- SiC . The strong dipolar and interfacial polarization derived from the fillers are responsible for the enhancement of the dielectric constant, while the formation of thermally conductive networks/chains by β- SiC whiskers contributes to the improved thermal conductivity.
Publisher: Elsevier BV
Date: 07-2004
Publisher: Springer Science and Business Media LLC
Date: 07-09-2012
Publisher: Elsevier BV
Date: 10-2018
Publisher: Open Engineering Inc
Date: 11-09-2019
Abstract: W-20wt.%Cu composite sheets with full density and good surface quality were successfully fabricated through an infiltration process followed by a hot rolling. After a total thickness reduction of 75%, the majority of the tungsten (W) particles have been deformed and elongated along the rolling direction. The aspect ratio of the W particles in the composite has reached 2.5. The relative density increases considerably to a maximum value of 99.8% when the rolling ratio increases. The thermal conductivity and microhardness of the W-Cu composites increase significantly with the rolling reduction. On the contrary, the coefficient of thermal expansion (CTE) of the composite s les decreases with the rolling ratio. Specifically, after subjected to 75% of thickness reduction, we obtained a large W-Cu thin sheet. This thin sheet demonstrates a low CTE of 7.27×10^-6/K and the highest thermal conductivity of 224.91 W/(m-K) both values are close to the respective theoretical ones.
Publisher: Elsevier BV
Date: 10-2015
Publisher: Elsevier BV
Date: 03-2014
Publisher: Wiley
Date: 06-03-2017
Publisher: MDPI AG
Date: 25-04-2019
DOI: 10.3390/MET9040481
Abstract: The hot deformation behavior and microstructure evolution of a 7.5 vol% TiBw/near α-Ti composite with fine matrix microstructure were investigated under the deformation conditions in a temperature range of 800–950 °C and strain rate range of 0.001–1 s−1 using plane strain compression tests. The flow stress curves show different characteristics according to the various deformation conditions. At a higher strain rate (1 s−1), the flow stress of the composite continuously increases until a peak value is reached. The activation energy is 410.40 kJ/mol, much lower than the activation energy of as-sintered or as-forged composites. The decreased activation energy is ascribed to the breaking of the TiBw reinforcement during the multi-directional forging and the resultant fine matrix microstructure. Refined reinforcement and refined matrix microstructure significantly improve the hot deformation ability of the composite. The deformation conditions determine the morphology and fraction of α and β phases. At 800–900 °C and 0.01 s−1 the matrix α grains are much refined due to the continuous dynamic recrystallization (CDRX). The processing map is constructed based on the hot deformation behavior and microstructure evolution. The optimal hot processing window is determined to be 800–950 °C/0.001–0.01 s−1, which lead to CDRX of primary α grains or dynamic recovery (DRV) and dynamic recrystallization (DRX) of β phase.
Publisher: Cassyni
Date: 13-10-2021
Publisher: Elsevier BV
Date: 04-2023
Publisher: World Scientific Pub Co Pte Lt
Date: 23-04-2015
DOI: 10.1142/S0217979215400032
Abstract: CaCu 3 Ti 4 O 12 (CCTO)–poly(vinylidene fluoride (PVDF)) composites were prepared by melt blending and hot molding techniques. The addition of CCTO remarkably enhanced the dielectric properties and the thermal conductivity of PVDF composites, while the melting point of the PVDF composites (~170°C) was almost independent of the CCTO concentration. Based on the results of dielectric constant and dielectric breakdown voltage, the PVDF composite containing 40 vol.% CCTO fillers shows the optimized capacitive energy storage potential (7.81 J/cm 3 ).
Publisher: Elsevier BV
Date: 04-2009
Publisher: Elsevier BV
Date: 08-2015
Publisher: Springer Science and Business Media LLC
Date: 16-12-2023
Publisher: MDPI AG
Date: 16-12-2020
DOI: 10.3390/MA13245751
Abstract: To further improve the mechanical properties of the as-cast 7.5 vol.% TiBw/Ti–6Al–2.5Sn–4Zr–0.7Mo–0.3Si composite, multi-directional forging (MDF) and subsequent heat treatments were carried out to adjust TiB whiskers (TiBw) and matrix characteristics. The effect of various microstructures on the tensile properties and fracture toughness of the composites was analyzed in this paper. After MDF, the TiBw are broken into short rods with a low aspect ratio and display a random distribution. Moreover, distinct microstructures were obtained after thermomechanical processing and different heat treatments. Both room-temperature and high-temperature tensile strength and ductility are improved after thermomechanical processing. By increasing the solution-treatment temperature, the microstructures transform from equiaxed to fully lamellar. A simultaneous improvement of the room-temperature and high-temperature properties is associated with the microstructural changes. In addition, the fracture toughness exhibits an increasing trend as the volume fraction of equiaxial α phases decreases. The lamellar microstructure demonstrates excellent fracture toughness due to deflection of the crack propagation path.
Publisher: Elsevier BV
Date: 12-2015
Publisher: Elsevier BV
Date: 03-0003
Publisher: Elsevier BV
Date: 11-2016
Publisher: Elsevier BV
Date: 2015
Publisher: Elsevier BV
Date: 03-2023
Publisher: Trans Tech Publications, Ltd.
Date: 08-2012
DOI: 10.4028/WWW.SCIENTIFIC.NET/KEM.520.161
Abstract: It has been two decades since the first report on titanium metal injection moulding (Ti-MIM) was published in 1988. The top secret for MIM practitioners and feedstock suppliers is the binder, which largely determines the success of Ti-MIM processes. As a consequence of its high affinity to oxygen and carbon, Ti injection moulding requires a more stringent control of contamination and therefore a different design strategy must be used for Ti-MIM binders, as compared to that for other metals injection moulding. This paper first discusses key requirements for Ti-MIM binder and then provides some case studies to discuss several major binders systems, followed by an outlook of the future binder development.
Publisher: Elsevier BV
Date: 05-2011
Publisher: MDPI AG
Date: 09-06-2023
Abstract: Solid composite electrolytes exhibit tremendous potential for practical all-solid-state lithium metal batteries (ASSLMBs), whereas the interfacial contact between cathode and electrolyte remains a long-standing problem. Herein, we demonstrate an integrated design of a double-layer functional composite electrolyte and cathode (ID-FCC), which effectively improves interfacial contact and increases cycle stability. One composite electrolyte layer, PVDFLiFSI@LLZNTO (PL1@L), comes into contact with the LLZNTO (Li6.5La3Zr1.5Nb0.4Ta0.1O12)-containing cathode, while the other layer, PEOLiTFSI@LLZNTO (PL2@L) with a Li anode, is introduced in each. Such a design establishes a continuous network for the transport of Li+ on the interface, and includes the advantages of both PEO and PVDF for improving stability with the electrodes. The Li symmetric cells Li/PL2@L-PL1@L-PL2@L/Li steadily cycled for more than 3800 h under the current density of 0.05 mA cm−2 at 60 °C. Outstandingly, the all-solid-state batteries of LiFePO4-ID-FCC/Li showed an initial specific capacity of 161.5 mA h g−1 at 60 °C, demonstrating a remaining capacity ratio of 56.1% after 1000 cycles at 0.1 C and 74.5% after 400 cycles at 0.5 C, respectively. This work provides an effective strategy for solid-state electrolyte and interface design towards ASSLMBs with high electrochemical performance.
Publisher: Trans Tech Publications, Ltd.
Date: 07-2011
DOI: 10.4028/WWW.SCIENTIFIC.NET/AMR.275.155
Abstract: Recently there is increasing demand for the development of new -type titanium with a low elastic modulus for surgical orthopaedic implant applications. In this paper, we developed a new Ti-Mo-Zr alloy based on the d-electron alloy design theory. The designed Ti-12Mo-5Zr (at%) alloy was then produced using ingot metallurgy and evaluated pertaining to the effect of heat treatment on the microstructure and mechanical properties. The alloy exhibited a relatively low Young’s modulus similar to some typical orthopaedic titanium alloys. Yield strength, tensile strength and Young’s modulus of the alloy decreased after solid solution treatment. The mechanism by which heat treatment affects the mechanical properties is discussed.
Publisher: MDPI AG
Date: 13-12-2016
DOI: 10.3390/MET6120309
Publisher: Elsevier BV
Date: 09-2016
Publisher: Trans Tech Publications, Ltd.
Date: 07-2013
DOI: 10.4028/WWW.SCIENTIFIC.NET/MSF.765.123
Abstract: The development of grain refinement technologies began in the 1930s in response to the need to improve the mechanical properties of as-cast components. Commercial grain refining technologies were developed by industrial and experimental trials often with good success including the production of effective master alloys. In parallel, researchers developed theories to explain the mechanisms of refinement in order to improve the efficiency of refiners and develop new better performing grain refining master alloys. This research continues today. Here we briefly present the history of these developments. It is shown that many developments in our understanding were based on assumptions arising from experimental and industrial observations and the prevailing solidification theories of the time.
Publisher: Springer Science and Business Media LLC
Date: 06-03-2015
Start Date: 2017
End Date: 2020
Funder: Royal Society of New Zealand
View Funded ActivityStart Date: 2018
End Date: 2021
Funder: Ministry of Business, Innovation and Employment
View Funded ActivityStart Date: 2022
End Date: 2025
Funder: Marsden Fund
View Funded ActivityStart Date: 2022
End Date: 2025
Funder: Marsden Fund
View Funded ActivityStart Date: 2019
End Date: 2022
Funder: Marsden Fund
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