Physics of the Body

Cameron, John; Skofronick, J. G.; Grant, Roderick M.

doi:10.54947/9781930524941

Cited by 8 publications

(7 citation statements)

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“…The densities of samples containing 30 and 40 vol.% of pore formers are highly reduced, around 60% with respect to the same Ti-xTa sample without large pores. This is beneficial for bone implants applications since the density reported for trabecular bones ranged between 0.8 and 1 g/cm 3 and compact bones ranges between 1.2 and 2 g/cm 3 [ 41 , 42 ]. This means that samples with 40 vol.% of pores are in the range, which are also in the range of the optimal density value 1.8 g/cm 3 suggested by Adamovic et al for bone implants [ 43 ].…”

Section: Resultsmentioning

confidence: 99%

Sintering Analysis of Porous Ti/xTa Alloys Fabricated from Elemental Powders

et al. 2022

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The present work is focused on developing Ti-xTa porous alloys processed by the space holder method and solid-state sintering. The volume fraction of Ta ranged between 20 and 30 wt.%. The sintering kinetics was evaluated by dilatometry tests. Sintered materials were characterized by SEM, XRD and computed tomography. Porosity features and permeability were determined from 3D images, and their mechanical properties were evaluated from microhardness and compression tests. The sintering behavior and the final microstructure are driven by the Ta diffusion into the Ti, slowing down the densification and modifying the transition temperature of α-to-β. Due to β-stabilization, martensite α′ was obtained after sintering. Mechanical properties are reduced because of the β-stabilization and pore addition, being predominantly the pore effect. Permeability depended on the pore characteristics, finding values close to the human bones. It was concluded that powder metallurgy generates highly TixTa alloys with a combination of α, β and α′ Ti phases as well as remaining Ta particles that are beneficial to improve the biocompatibility and osseointegration of such materials. Being the Ti25Ta40salt alloy the most suitable for orthopedic implants because of its characteristics and properties.

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Section: Resultsmentioning

confidence: 99%

Sintering Analysis of Porous Ti/xTa Alloys Fabricated from Elemental Powders

et al. 2022

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“…The density of the two-layer sample is 6.16 g/cm 3 , which reduces the density of porous Ta by 20%. Note that the density of human bones is in the range 0.8-1 g/cm 3 for trabecular bones and 1.2-2 g/cm 3 for compact bones [38,39], and it has been suggested that the optimal weight density for an implant is 1.8 g/cm 3 [40].…”

Section: Microstructural Characterizationmentioning

confidence: 99%

Design of Ti64/Ta Hybrid Materials by Powder Metallurgy Mimicking Bone Structure

et al. 2023

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This work reports on the fabrication of a novel two-layer material composed of a porous tantalum core and a dense Ti6Al4V (Ti64) shell by powder metallurgy. The porous core was obtained by mixing Ta particles and salt space-holders to create large pores, the green compact was obtained by pressing. The sintering behavior of the two-layer sample was studied by dilatometry. The interface bonding between the Ti64 and Ta layers was analyzed by SEM, and the pore characteristics were analyzed by computed microtomography. Images showed that two distinct layers were obtained with a bonding achieved by the solid-state diffusion of Ta particles into Ti64 during sintering. The formation of β-Ti and α′ martensitic phases confirmed the diffusion of Ta. The pore size distribution was in the size range of 80 to 500 µm, and a permeability value of 6 × 10−10 m2 was close to the trabecular bones one. The mechanical properties of the component were dominated mainly by the porous layer, and Young’s modulus of 16 GPa was in the range of bones. Additionally, the density of this material (6 g/cm3) was much lower than the one of pure Ta, which helps to reduce the weight for the desired applications. These results indicate that structurally hybridized materials, also known as composites, with specific property profiles can improve the response to osseointegration for bone implant applications.

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“…The box in Figure 1 represents this substantial volume, which is ≈340 times the chicken's skeleton volume at hatching, based on a bone density of 1900 kg m −3 . [ 21 ] Thus, the mineralization process raises a considerable challenge in terms of throughput of serum and transport of ions from the serum to the site of deposition. While calcium‐binding proteins, most notably Fetuin‐A, [ 22 ] are known to support the vascular transport of calcium, the situation is much less clear when it comes to the transport beyond the vascular system, through newly formed collagenous osteoid.…”

Section: Introductionmentioning

confidence: 99%

Logistics of Bone Mineralization in the Chick Embryo Studied by 3D Cryo FIB‐SEM Imaging

et al. 2023

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During skeletal development, bone growth and mineralization require transport of substantial amounts of calcium, while maintaining very low concentration. How an organism overcomes this major logistical challenge remains mostly unexplained. To shed some light on the dynamics of this process, cryogenic focused ion beam-scanning electron microscopy (cryo-FIB/SEM) is used to image forming bone tissue at day 13 of a chick embryo femur. Both cells and matrix in 3D are visualized and observed as calcium-rich intracellular vesicular structures. Counting the number of these vesicles per unit volume and measuring their calcium content based on the electron back-scattering signal, the intracellular velocity at which these vesicles need to travel to transport all the calcium required for the mineral deposited in one day within the collagenous tissue can be estimated. This velocity at 0.27 μm s −1 is estimated, which is too large for a diffusion process and rather suggests active transport through the cellular network. It is concluded that calcium logistics is hierarchical and based on several transport mechanisms: first through the vasculature using calcium-binding proteins and the blood flow, then active transport over tens of micrometers through the network of osteoblasts and osteocytes, and finally diffusive transport over the last one or two microns.

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Physics of the Body

Cited by 8 publications

References 0 publications

Sintering Analysis of Porous Ti/xTa Alloys Fabricated from Elemental Powders

Sintering Analysis of Porous Ti/xTa Alloys Fabricated from Elemental Powders

Design of Ti64/Ta Hybrid Materials by Powder Metallurgy Mimicking Bone Structure

Logistics of Bone Mineralization in the Chick Embryo Studied by 3D Cryo FIB‐SEM Imaging

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