scholarly journals Mechanical Analysis and Corrosion Analysis of Zinc Alloys for Bioabsorbable Implants for Osteosynthesis

Materials ◽  
2022 ◽  
Vol 15 (2) ◽  
pp. 421
Salome Hagelstein ◽  
Sergej Zankovic ◽  
Adalbert Kovacs ◽  
Roland Barkhoff ◽  
Michael Seidenstuecker

Zinc alloys have recently been researched intensely for their great properties as bioabsorbable implants for osteosynthesis. Pure zinc (Zn) itself has relatively poor strength, which makes it insufficient for most clinical use. Research has already proven that the mechanical strength of zinc can be enhanced significantly by alloying it with silver. This study evaluated zinc silver alloys (ZnAg) as well as novel zinc silver titanium alloys (ZnAgTi) regarding their mechanical properties for the use as bioabsorbable implants. Compared to pure zinc the mechanical strength was enhanced significantly for all tested zinc alloys. The elastic properties were only enhanced significantly for the zinc silver alloys ZnAg6 and ZnAg9. Regarding target values for orthopedic implants proposed in literature, the best mechanical properties were measured for the ZnAg3Ti1 alloy with an ultimate tensile strength of 262 MPa and an elongation at fracture of 16%. Besides the mechanical properties, the corrosion rates are important for bioabsorbable implants. This study tested the corrosion rates of zinc alloys in PBS solution (phosphate buffered solution) with electrochemical corrosion measurement. Zinc and its alloys showed favorable corrosion rates, especially in comparison to magnesium, which has a much lower degradation rate and no buildup of hydrogen gas pockets during the process. Altogether, this makes zinc alloys highly favorable for use as material for bioabsorbable implants for osteosynthesis.

2021 ◽  
Vol 22 (2) ◽  
pp. 5-16
O.D. Pavlov ◽  
V.V. Pastukh ◽  
M.Yu. Karpinsky

Diseases and injuries of the musculoskeletal system rank second among the causes of injuries and third among the diseases that lead to disability of the adult population. Orthopedic implants have a special place in both clinical practice and the biomedical industry. The implants capable of biodegrading in the case of their implantation into the human body are of the greatest interest. The concept of biodegra-dable implants appeared through the formation and development of the use of suture materials that are absorbed in the body. Subsequently, this type of material began to be used in the treatment of fractures, because in many cases, bone fragments need only temporary support with a fixator, until they fuse. Implantable internal fixation devices for fracture repair using polyglycolic acid (PGA), polylactic acid (PLA), and a copolymer of lactic acid and glycolide (PLGA) became popular. However, the mechanical properties of highly porous skeletons were relatively weak compared to those required for bone engineering. In the process of creating an optimal polymeric biodegradable material, it is necessary to overcome the contradiction between strength and biodegradation. PGA, providing high strength of fixation, degrade too quickly, and PLGA, having high crystallinity, slightly degrade, at the same time conceding on the durability of both PGA and biostable materials. Scientists are now working hard to develop composites from calcium phosphate and polymer, in particular hydroxyapatite and tricalсium phosphate (TCP). TCP with three polymorphic modifications, in particular α-TCP, β-TCP, and α'-TCP, is a well-known bioceramic substance for bone repair. β-TKP is attracting increasing attention due to its excellent biocompatibility, bioactivity, and biodegradability. The composite materials based on bioactive ceramics mainly refer to materials with additional advantages, such as biodegradable polymers and ceramics. At the same time, these composites are biocompatible, osteoconductive, mechanical strength and have osteogenic characteristics. At the same time, thanks to new manufacturing technologies that have emerged in recent years, these compo-site materials are the most promising in the field of bone defect repair. The treatment of fractures with implants is increasingly associated with composite materials. Biomaterials must have certain mechanical properties: biocompatibility, biodegradation, controlled rate biodegradation, good mechanical strength, and bioactivity. Biomaterials used in the treatment of bone fractures have to disintegrate over time, and the addition of nanofillers can slow down the rate of decay of the biodegradable composite.

Materials ◽  
2019 ◽  
Vol 12 (2) ◽  
pp. 295 ◽  
Sébastien Champagne ◽  
Ehsan Mostaed ◽  
Fariba Safizadeh ◽  
Edward Ghali ◽  
Maurizio Vedani ◽  

Absorbable metals have potential for making in-demand rigid temporary stents for the treatment of urinary tract obstruction, where polymers have reached their limits. In this work, in vitro degradation behavior of absorbable zinc alloys in artificial urine was studied using electrochemical methods and advanced surface characterization techniques with a comparison to a magnesium alloy. The results showed that pure zinc and its alloys (Zn–0.5Mg, Zn–1Mg, Zn–0.5Al) exhibited slower corrosion than pure magnesium and an Mg–2Zn–1Mn alloy. The corrosion layer was composed mostly of hydroxide, carbonate, and phosphate, without calcium content for the zinc group. Among all tested metals, the Zn–0.5Al alloy exhibited a uniform corrosion layer with low affinity with the ions in artificial urine.

2021 ◽  
Vol 7 (1) ◽  
pp. eabc5442
Dianyu Dong ◽  
Caroline Tsao ◽  
Hsiang-Chieh Hung ◽  
Fanglian Yao ◽  
Chenjue Tang ◽  

The high mechanical strength and long-term resistance to the fibrous capsule formation are two major challenges for implantable materials. Unfortunately, these two distinct properties do not come together and instead compromise each other. Here, we report a unique class of materials by integrating two weak zwitterionic hydrogels into an elastomer-like high-strength pure zwitterionic hydrogel via a “swelling” and “locking” mechanism. These zwitterionic-elastomeric-networked (ZEN) hydrogels are further shown to efficaciously resist the fibrous capsule formation upon implantation in mice for up to 1 year. Such materials with both high mechanical properties and long-term fibrous capsule resistance have never been achieved before. This work not only demonstrates a class of durable and fibrous capsule–resistant materials but also provides design principles for zwitterionic elastomeric hydrogels.

Metals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 519
Devadas Bhat Panemangalore ◽  
Rajashekhara Shabadi ◽  
Manoj Gupta

In this study, the effect of calcium (Ca) and erbium (Er) on the microstructure, mechanical properties, and corrosion behavior of magnesium-zinc alloys is reported. The alloys were prepared using disintegrated melt deposition (DMD) technique using the alloying additions as Zn, Ca, and Mg-Er master alloys and followed by hot extrusion. Results show that alloying addition of Er has significantly reduced the grain sizes of Mg-Zn alloys and also when compared to pure magnesium base material. It also has substantially enhanced both the tensile and the compressive properties by favoring the formation of MgZn2 type secondary phases that are uniformly distributed during hot-extrusion. The quaternary Mg-Zn-Ca-Er alloy exhibited the highest strength due to lower grain size and particle strengthening due to the influence of the rare earth addition Er. The observed elongation was a result of extensive twinning observed in the alloys. Also, the degradation rates have been substantially reduced as a result of alloying additions and it is attributed to the barrier effect caused by the secondary phases.

Materials ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3467
Anna Nocivin ◽  
Doina Raducanu ◽  
Bogdan Vasile ◽  
Corneliu Trisca-Rusu ◽  
Elisabeta Mirela Cojocaru ◽  

The present paper analyzed the microstructural characteristics and the mechanical properties of a Ti–Nb–Zr–Fe–O alloy of β-Ti type obtained by combining severe plastic deformation (SPD), for which the total reduction was of etot = 90%, with two variants of super-transus solution treatment (ST). The objective was to obtain a low Young’s modulus with sufficient high strength in purpose to use the alloy as a biomaterial for orthopedic implants. The microstructure analysis was conducted through X-ray diffraction (XRD), scanning electron microscopy (SEM), and high-resolution transmission electron microscopy (HRTEM) investigations. The analyzed mechanical properties reveal promising values for yield strength (YS) and ultimate tensile strength (UTS) of about 770 and 1100 MPa, respectively, with a low value of Young’s modulus of about 48–49 GPa. The conclusion is that satisfactory mechanical properties for this type of alloy can be obtained if considering a proper combination of SPD + ST parameters and a suitable content of β-stabilizing alloying elements, especially the Zr/Nb ratio.

2021 ◽  
Vol 11 (1) ◽  
Shobair Mohammadi Mozvashi ◽  
Mohammad Ali Mohebpour ◽  
Sahar Izadi Vishkayi ◽  
Meysam Bagheri Tagani

AbstractVery recently, a novel phase of hydrogenated borophene, namely $$\alpha '$$ α ′ -4H, has been synthesized in a free-standing form. Unlike pure borophenes, this phase shows very good stability in the air environment and possesses semiconducting characteristics. Because of the interesting stiffness and flexibility of borophenes, herein, we systematically studied the mechanical properties of this novel hydrogenated phase. Our results show that the monolayer is stiffer (Y$$_\text {xy}$$ xy = $$\sim $$ ∼ 195 N/m) than group IV and V 2D materials and even than MoS$$_2$$ 2 , while it is softer than graphene. Moreover, similar to other phases of borophene, the inherent anisotropy of the pure monolayer increases with hydrogenation. The monolayer can bear biaxial, armchair, and zigzag strains up to 16, 10, and 14% with ideal strengths of approximately 14, 9, and 12 N/m, respectively. More interestingly, it can remain semiconductor under this range of tension. These outstanding results suggest that the $$\alpha '$$ α ′ -4H is a promising candidate for flexible nanoelectronics.

1997 ◽  
Vol 12 (4) ◽  
pp. 1091-1101 ◽  
Seunggu Kang ◽  
Hongy Lin ◽  
Delbert E. Day ◽  
James O. Stoffer

The dependence of the optical and mechanical properties of optically transparent polymethyl methacrylate (PMMA) composites on the annealing temperature of BK10 glass fibers was investigated. Annealing was used to modify the refractive index (R.I.) of the glass fiber so that it would more closely match that of PMMA. Annealing increased the refractive index of the fibers and narrowed the distribution of refractive index of the fibers, but lowered their mechanical strength so the mechanical properties of composites reinforced with annealed fibers were not as good as for composites containing as-pulled (chilled) glass fibers. The refractive index of as-pulled 17.1 μm diameter fibers (R.I. = 1.4907) increased to 1.4918 and 1.4948 after annealing at 350 °C to 500 °C for 1 h or 0.5 h, respectively. The refractive index of glass fibers annealed at 400 °C/1 h best matched that of PMMA at 589.3 nm and 25 °C, so the composite reinforced with those fibers had the highest optical transmission. Because annealed glass fibers had a more uniform refractive index than unannealed fibers, the composites made with annealed fibers had a higher optical transmission. The mechanical strength of annealed fiber/PMMA composites decreased as the fiber annealing temperature increased. A composite containing fibers annealed at 450 °C/1 h had a tensile strength 26% lower than that of a composite made with as-pulled fibers, but 73% higher than that for unreinforced PMMA. This decrease was avoided by treating annealed fibers with HF. Composites made with annealed and HF (10 vol. %)-treated (for 30 s) glass fibers had a tensile strength (∼200 MPa) equivalent to that of the composites made with as-pulled fibers. However, as the treatment time in HF increased, the tensile strength of the composites decreased because of a significant reduction in diameter of the glass fiber which reduced the volume percent fiber in the composite.

2015 ◽  
Vol 749 ◽  
pp. 278-281
Jia Horng Lin ◽  
Jing Chzi Hsieh ◽  
Jin Mao Chen ◽  
Wen Hao Hsing ◽  
Hsueh Jen Tan ◽  

Geotextiles are made of polymers, and their conjunction with different processes and materials can provide geotextiles with desirable characteristics and functions, such as filtration, separation, and drainage, and thereby meets the environmental requirements. Chemical resistant and mechanical strong polymers, including polyester (PET) and polypropylene (PP), are thus used to prolong the service life of the products made by such materials. This study proposes highly air permeable geotextiles that are made with different thicknesses and various needle punching speeds, and the influences of these two variables over the pore structure and mechanical properties are then examined. PET fibers, PP fibers, and recycled Kevlar fibers are blended, followed by being needle punched with differing spaces and speeds to form geotextiles with various thicknesses and porosities. The textiles are then evaluated for their mechanical strength and porosity. The test results show that a thickness of 4.5 cm and 1.5 cm demonstrate an influence on the tensile strength of the geotextiles, which is ascribed to the webs that are incompletely needle punched. However, the excessive needle punching speed corresponding to a thickness of 0.2 cm results in a decrease in tensile strength, but there is also an increase in the porosity of the geotextiles.

2021 ◽  
Erling Østby ◽  
Bjørn-Andreas Hugaas ◽  
Agnes Marie Horn

Abstract Considering the vast number of articles that have been published during the last 150 years related to hydrogen embrittlement and the multiple attempts to explain the governing mechanisms, it is evident that hydrogen’s effect on mechanical properties in steel is still a controversial topic. This little atom has even by some authors been referred to as the “little devil”. We do not intend to explore this particular description of hydrogen any further. However, we would like to shed some light on the key technical aspects we believe need to be further scrutinized and understood to ensure that the decision-makers have sufficiently reliable data available to decide whether hydrogen gas can be safely transported in new or existing offshore pipelines at an acceptable cost.

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