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1.
Sensors (Basel) ; 22(15)2022 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-35957470

RESUMO

Fragment kinetic energy is an important parameter to characterize the damage power of fragments. In this study, an acoustic emission technology-based method to evaluate fragment kinetic energy is proposed. The dynamic response of the fragment impacting an aluminum alloy target plate and the relationship between the initial kinetic energy of the fragment impact and the acoustic emission waveform were theoretically evaluated; the numerical simulation of typical spherical fragments (8 mm diameter) penetrating the aluminum alloy target plate was performed, the wavelet energy of the acoustic emission signal was obtained using wavelet packet theory, and a mathematical model of wavelet energy and fragment kinetic energy was constructed. A fragment kinetic energy test system was established, and a fragment penetration test was performed. The analysis showed that the wavelet energy mathematical models and the fragment kinetic energy exhibited favorable consistency, and the measurement errors of the three experiments were 3%, 3.7%, and 3%. This demonstrates the effectiveness of the typical acoustic emission fragment kinetic energy test methods proposed in this study and establishes a new method for the direct measurement of fragment kinetic energy.


Assuntos
Acústica , Alumínio , Ligas , Simulação por Computador , Tecnologia
2.
Nature ; 608(7922): 270-271, 2022 08.
Artigo em Inglês | MEDLINE | ID: mdl-35948706

Assuntos
Ligas
3.
PLoS One ; 17(8): e0272387, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35913977

RESUMO

Titanium alloys have great potential in ultra-precision situations due to the excellent properties, such as high corrosion resistance, high specific-strength and high biocompatibility. However, the application of titanium alloys in ultra-precision field is limited by the poor machinability. There are difficulties in obtaining the optical surface. In this study, the possibility for obtaining optically graded surfaces of titanium alloys by ultra-precision polishing was investigated. Before the ultra-precision polishing, ultra-precision turning with a single point diamond tool was used to get all sample surfaces. But, titanium alloy is difficult to obtain good surface quality by ultra-precision diamond turning. The samples results confirmed that most of the surface roughness values are higher than 30 nm. In order to explore the polishing process, a large number of ultra-precision polishing experiments were conducted. In addition, the effects of different ultra-precision polishing parameters on the surface profiles of titanium alloy Ti6Al4V were investigated in depth. The results show that the average values of surface roughness of titanium alloy parts with ultra-precision turning can be further reduced by 70% or so by ultra-precision polishing. Using a reasonable combination of high spindle speed and large cutting depth, the value of surface roughness can even be lower than 2 nm.


Assuntos
Ligas , Titânio , Polimento Dentário , Diamante , Teste de Materiais , Propriedades de Superfície
4.
Sci Rep ; 12(1): 13163, 2022 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-35915147

RESUMO

Biofilms, are significant component that contributes to the development of chronic infections, especially when medical devices are involved. This issue offers a huge challenge for the medical community since standard antibiotics are only capable of eradicating biofilms to a very limited degree. The prevention of biofilm formation have led to the development of a variety of coating methods and new materials. These methods are intended to coat surfaces in such a way as to inhibit the formation of biofilm. Metallic glassy alloys, in particular, alloys that include copper and titanium metals have gained popularity as desirable antibacterial coating. Meanwhile, there has been a rise in the use of the cold spray coating technique due to the fact that it is a proper approach for processing temperature-sensitive materials. The present study was carried out in part with the intention of developing a new antibiofilm metallic glassy consisting of ternary Cu-Zr-Ni using mechanical alloying technique. The spherical powders that comprised the end-product were utilized as feedstock materials for cold spray coatings to stainless steel surfaces at low temperature. When compared to stainless steel, substrates coated with metallic glassy were able to significantly reduce the formation of biofilm by at least one log.


Assuntos
Nanopartículas , Aço Inoxidável , Ligas/química , Antibacterianos/química , Antibacterianos/farmacologia , Biofilmes , Materiais Revestidos Biocompatíveis/química , Pós , Aço Inoxidável/química , Titânio/química
5.
Biomater Adv ; 137: 212869, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35929245

RESUMO

Diabetic chronic wound healing is a critical clinical challenge due to the particularity of wound microenvironment, including hyperglycemia, excessive oxidative stress, hypoxia, and bacterial infection. Herein, we developed a multifunctional self-healing hydrogel dressing (defined as OHCN) to regulate the complex microenvironment of wound for accelerative diabetic wound repair. The OHCN hydrogel dressing was constructed by integrating Au-Pt alloy nanoparticles into a hydrogel (OHC) that formed through Schiff-base reaction between oxidized hyaluronic acid (OHA) and carboxymethyl chitosan (CMCS). The dynamic cross-linking of OHA and antibacterial CMCS imparted the OHCN hydrogel dressing with excellent antibacterial and self-healing properties. Meanwhile, Au-Pt alloy nanoparticles endowed the OHCN hydrogel dressing with the functions of lowering blood glucose, alleviating oxidative damage, and providing O2 by simulating glucose oxidase and catalase. Through a synergistic combination of OHC hydrogel and Au-Pt alloy nanoparticles, the resulted OHCN hydrogel dressing significantly ameliorated the pathological microenvironment and accelerated the healing rate of diabetic wound. The proposed nanozyme-decorated multifunctional hydrogel offers an efficient strategy for the improved management of diabetic chronic wound.


Assuntos
Diabetes Mellitus , Hidrogéis , Ligas , Antibacterianos , Bandagens , Humanos , Hidrogéis/farmacologia , Cicatrização
6.
Biomater Adv ; 137: 212829, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35929262

RESUMO

Lattice structures are widely used in orthopedic implants due to their unique features, such as high strength-to-weight ratios and adjustable biomechanical properties. Based on the type of unit cell geometry, lattice structures may be classified into two types: strut-based structures and sheet-based structures. In this study, strut-based structures (Cubic & Octet) and sheet-based structure (triply periodic minimal surface (TPMS) gyroid) were investigated. The biomechanical properties of the three different Ti6Al4V lattice structures fabricated by selective laser melting (SLM) were investigated using room temperature compression testing. Scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) were used to check the 3D printing quality with regards to defects and quantitative compositional information of 3D printed parts. Experimental results indicated that TPMS gyroid has superior biomechanical properties when compared to Cubic and Octet. Also, TPMS gyroid was found to be less affected by the variations in relative density. The biocompatibility of Ti6Al4V lattice structures was validated through the cytotoxicity test with human osteoblast-like SAOS2 cells. The debris generated during the degradation process in the form of particles and ions is among the primary causes of implant failure over time. In this study, Ti6Al4V particles with spherical and irregular shapes having average particle sizes of 36.5 µm and 28.8 µm, respectively, were used to mimic the actual Ti6Al4V particles to understand their harmful effects better. Also, the effects and amount of Ti6Al4V ions released after immersion within the cell culture media were investigated using the indirect cytotoxicity test and ion release test.


Assuntos
Lasers , Osteoblastos , Ligas , Humanos , Teste de Materiais , Porosidade , Titânio
7.
Biomater Adv ; 136: 212791, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35929324

RESUMO

Tailoring surface properties by layer-by-layer (LBL) deposition directed on the construction of complex multilayer coatings with nanoscale precision enables the development of novel structures and devices with desired functional properties (i.e., osseointegration, bactericidal activity, biocorrosion protection). Herein, electrostatic self-assembly was applied to fabricate biopolymer-based coatings involving chitosan (CSM) and alginate (AL) enriched with caffeic acid (CA) on Ti-6Al-7Nb alloyed surfaces. The method of CA grafting onto the chitosan backbone (CA-g-CSM) as well as all used reagents for implant functionalization were chosen as green and sustainable approach. The final procedure of surface modification of the Ti-6Al-7Nb alloy consists of three steps: (i) chemical treatment in Piranha solution, (ii) plasma chemical-activation of the Ti alloy surface in a RF CVD (Radio Frequency Chemical Vapour Deposition) reactor using Ar, O2 and NH3 gaseous precursors, and (iii) a multi-step deposition of bio-functional coatings via dip-coating method. Corrosion tests have revealed that the resulting chitosan-based coatings, also these involving CA, block the specimen surface and hinder corrosion of titanium alloy. Furthermore, the antioxidant layers are characterized by beneficial level of roughness (Ra up ca. 350 nm) and moderate hydrophilicity (59°) with the dispersion part of conducive surface energy ca. 30 mJ/m2. Noteworthy, all coatings are biocompatible as the intact morphology of cultured eukaryotic cells ensured proper growth and proliferation, while exhibit bacteriostatic character, particularly in contact with Gram-(-) bacteria (E. coli). The study indicates that the applied simple sustainable strategy has contributed significantly to obtaining homogeneous, stable, and biocompatible while antibacterial biopolymer-based coatings.


Assuntos
Quitosana , Titânio , Ligas , Ácidos Cafeicos , Quitosana/química , Escherichia coli , Imersão , Eletricidade Estática , Titânio/química
8.
PLoS One ; 17(8): e0271583, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35926058

RESUMO

In this study, a comprehensive treatment process based on the rotary injection of Ar+CO2 Mg-Al alloy melt is proposed. The effect of carbon on the grain refinement of Mg-Al alloy is studied according to the proposed integrated treatment process. The regularity of carbon refinement in the Mg-Al alloy is examined by microstructural observation and theoretical calculation. The results show that carbon has no effect on the grain refinement of Mg-Al alloy when the Al content is less than 1wt.%. However, when the Al content reaches 2 wt.%, the refining effect is obvious, and the grain refinement efficiency is 62%. The refining effect increases with the increase in the Al content, and the refinement efficiency becomes 79% when the Al content reaches 9 wt.%. The size of Al-C-O in the matrix is approximately 5µm, which confirms the existence of Al4C3 phase exists as a heterogeneous nucleating agent. The theoretical calculations suggest that the Al4C3 heterogeneous nucleating agent cannot be formed when the Al content in the Mg alloy is less than 1.34%, so there is no thinning effect under such Al content. The crystallographic calculations reveal that the mismatch between the Al4C3 phase and Mg alloy matrix is only 4.05%, and Al4C3 can exist as a heterogeneous nucleating agent for α-Mg phase. Combining the measured solidification curves with the classical nucleation theory, the wetting angle of Mg-Al alloy on Al4C3 is calculated to be 24.3°.


Assuntos
Ligas , Carbono , Ligas/química
9.
Sensors (Basel) ; 22(15)2022 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-35957170

RESUMO

Shape memory materials are smart materials that stand out because of several remarkable properties, including their shape memory effect. Shape memory alloys (SMAs) are largely used members of this family and have been innovatively employed in various fields, such as sensors, actuators, robotics, aerospace, civil engineering, and medicine. Many conventional, unconventional, experimental, and numerical methods have been used to study the properties of SMAs, their models, and their different applications. These materials exhibit nonlinear behavior. This fact complicates the use of traditional methods, such as the finite element method, and increases the computing time necessary to adequately model their different possible shapes and usages. Therefore, a promising solution is to develop new methodological approaches based on artificial intelligence (AI) that aims at efficient computation time and accurate results. AI has recently demonstrated some success in efficiently modeling SMA features with machine- and deep-learning methods. Notably, artificial neural networks (ANNs), a subsection of deep learning, have been applied to characterize SMAs. The present review highlights the importance of AI in SMA modeling and introduces the deep connection between ANNs and SMAs in the medical, robotic, engineering, and automation fields. After summarizing the general characteristics of ANNs and SMAs, we analyze various ANN types used for modeling the properties of SMAs according to their shapes, e.g., a wire as an actuator, a wire with a spring bias, wire systems, magnetic and porous materials, bars and rings, and reinforced concrete beams. The description focuses on the techniques used for NN architectures and learning.


Assuntos
Ligas , Ligas de Memória da Forma , Inteligência Artificial , Redes Neurais de Computação , Porosidade
10.
Biomater Adv ; 138: 212875, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35913254

RESUMO

A newly developed ß-Ti alloy based on the Ti-Nb-Zr-Ta system (Ti20Nb20Zr4Ta) has been subjected to Plasma Electrolytic Oxidation (PEO) treatment to obtain a multifunctional ceramic-like (TiO2) coating with superior tribocorrosion (wear and corrosion) resistance and improved biocompatibility. For this aim, elements such as Ca, P, and Ag NPs have been incorporated into the oxide film to obtain bioactive and biocide properties. The chemical composition and morphology of the TiO2-PEO coating was characterized, and its multifunctionality was addressed by several means, including antibacterial activity assessment, formation of bone-like apatite, metallic ion release evaluation, in vitro cellular response analysis, and corrosion and tribocorrosion tests in artificial saliva. The developed coatings enhanced the corrosion and tribocorrosion resistance of the bare alloy and exhibited antibacterial ability with low cytotoxicity and negligible ion release. Furthermore, they were able to sustain MC3T3-E1 preosteoblast viability/proliferation and osteogenic differentiation. Altogether, the results obtained demonstrate the potential of the TiO2 coating incorporating Ca, P, and Ag NPs to be used for dental applications.


Assuntos
Ligas , Materiais Revestidos Biocompatíveis , Ligas/química , Antibacterianos/farmacologia , Materiais Revestidos Biocompatíveis/química , Osteogênese , Propriedades de Superfície , Titânio
11.
Acta Biomater ; 149: 387-398, 2022 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-35817341

RESUMO

This study systematically investigated the effect of equal channel angular pressing (ECAP) on the microstructure, mechanical, corrosion, nano-tribological properties and biocompatibility of a newly developed ß Ti-28Nb-35.4Zr (hereafter denoted TNZ) alloy. Results indicated that ECAP of the ß TNZ alloy refined its microstructure by forming ultrafine grains without causing stress-induced phase transformation, leading to formation of a single ß phase. The ECAP-processed TNZ alloy exhibited a compressive yield strength of 960 MPa, and high plastic deformation capacity without fracturing under compression loads. Potentiodynamic polarization tests revealed the higher tendency of ECAP-processed TNZ alloys to form passive oxide films on its surface, which exhibited a lower corrosion rate (0.44±0.07 µm/y) in Hanks' balanced salt solution compared to its as-cast counterpart (0.71±0.10 µm/y). Nanotribological testing also revealed higher resistance of the ECAP-processed TNZ alloy to abrasion, wear and scratching, when compared to its as-cast counterpart. Cytocompatibility and cell adhesion assessments of the ECAP-processed TNZ alloys showed a high viability (111%) of human osteoblast-like SaOS2 cells after 7 d of culturing. Moreover, the ECAP-processed TNZ alloy promoted adhesion and spreading of SaOS2 cells, which exhibited growth and proliferation on alloy surfaces. In summary, significantly enhanced mechanical, corrosion, and biological properties of ECAP-processed TNZ alloy advocate its suitability for load-bearing implant applications. STATEMENT OF SIGNIFICANCE: Equal channel angular pressing (ECAP) provides a unique combination of enhanced mechanical and functional properties of materials by optimizing their microstructures and phase transformations. This study investigated the mechanical, nano-tribological, corrosion, and biocompatibility properties of a newly developed ß Ti-28Nb-35.4Zr (TNZ) alloy processed via ECAP. Our findings indicated that ECAP of the ß TNZ alloy refined its microstructure by forming ultrafine grains without causing stress-induced phase transformation. Compared to its as-cast counterpart, ECAP-processed TNZ exhibited significantly enhanced compressive yield strength, plastic deformation capacity, hardness, wear, and corrosion properties. Moreover, in vitro cytocompatibility and cell adhesion studies revealed high cellular viabilities, growth and proliferation of osteoblast-like SaOS2 cells on the ECAP-processed TNZ alloy.


Assuntos
Ligas , Titânio , Ligas/química , Ligas/farmacologia , Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Força Compressiva , Corrosão , Humanos , Teste de Materiais , Plásticos , Titânio/química , Titânio/farmacologia
12.
ACS Appl Bio Mater ; 5(8): 3982-3990, 2022 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-35822695

RESUMO

Extracellular matrices (ECMs) provide important cues for cell proliferation and differentiation in the complex environment, which show a significant influence on cell functions. Herein, cell-derived ECMs were deposited on the polydopamine (PDA)-decorated porous Ti-24Nb-4Zr-8Sn (Ti2448) scaffolds fabricated by the electron beam melting method in order to improve biological functions. The influence of PDA-ECM coatings on cell functions was further investigated. The results demonstrated that the PDA-ECM coating facilitated adhesion, proliferation, and migration of MC3T3-E1 cells on Ti2448 scaffolds. Moreover, Ti2448-PDA-ECM scaffolds promoted osteogenesis differentiation of cells indicated by greater alkaline phosphatase activity and further mineralization, compared to the plain Ti2448 group. Meanwhile, Ti2448-PDA-ECM scaffolds enhanced bone growth after implantation for one month in rabbit femoral bone defects. Our findings suggest that the bioinspired PDA-ECM coating can be implemented on the porous Ti2448 scaffolds, which significantly improve the biological functions of orthopedic implants.


Assuntos
Ligas , Polímeros , Animais , Matriz Extracelular , Indóis , Coelhos
13.
Biointerphases ; 17(4): 041001, 2022 07 06.
Artigo em Inglês | MEDLINE | ID: mdl-35794027

RESUMO

In this study, casting, extrusion, biocorrosion, and corrosive wear properties of 0.5 wt. % (Zn, Ca, and Nd) element added Mg-3 wt. % Ag alloys were investigated. According to the test results, it was observed that the grain refinement occurred with the effect of Zn and Ca element additions in the as-cast alloys and thus some mechanical properties of the alloys improved. Similarly, the extrusion process provided grain refinement and improved mechanical properties. As a result of in vitro corrosion tests, similar results were also obtained in the as-cast alloys, while this situation became more apparent in the extruded alloys and exhibited more homogeneous corrosion properties. In the corrosive wear tests, the wear rate of the extruded alloys generally showed a decreasing trend. However, both the as-cast and extruded Mg-3 wt. %Ag-0.5 wt. % Ca alloys exhibited the lowest wear rate.


Assuntos
Ligas , Cáusticos , Ligas/química , Materiais Biocompatíveis/química , Corrosão , Magnésio , Zinco/química
14.
Regul Toxicol Pharmacol ; 133: 105227, 2022 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-35817207

RESUMO

Stainless steels are widely used iron-based alloys that contain chromium and, typically, other alloying elements. The chromium(III)-rich surface oxide of stainless steels efficiently limits the release (bioaccessibility) of their metal constituents in most physiological environments, influencing the toxicity of the alloy. Of the constituents and impurities of stainless steels, nickel and cobalt are of particular interest, primarily due to skin sensitization and repeated-dose inhalation toxicity of nickel, and (inhalation) carcinogenicity of cobalt. A review of the available toxicological data on stainless steels, and the toxicological, mechanistic, and bioaccessibility data on their constituent metals supports the low toxicity and non-carcinogenicity of stainless steels. The comparative metal release, rather than the bulk composition of stainless steels, needs to be considered when assessing their health hazard classification according to the UN Globally Harmonized System, and the corresponding EU CLP regulation. As an illustrative example, a 28-day inhalation toxicity study on stainless steel powder showed no signs of lung toxicity at exposure levels at which significant toxicity would have been expected on the basis of its bulk nickel content. This finding is associated with the low bioaccessibility of nickel from the alloy in the lungs.


Assuntos
Níquel , Aço Inoxidável , Ligas/toxicidade , Cromo/toxicidade , Cobalto , Níquel/toxicidade , Aço Inoxidável/toxicidade , Aço
15.
Nat Commun ; 13(1): 4040, 2022 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-35831304

RESUMO

Memristors, or memristive devices, have attracted tremendous interest in neuromorphic hardware implementation. However, the high electric-field dependence in conventional filamentary memristors results in either digital-like conductance updates or gradual switching only in a limited dynamic range. Here, we address the switching parameter, the reduction probability of Ag cations in the switching medium, and ultimately demonstrate a cluster-type analogue memristor. Ti nanoclusters are embedded into densified amorphous Si for the following reasons: low standard reduction potential, thermodynamic miscibility with Si, and alloy formation with Ag. These Ti clusters effectively induce the electrochemical reduction activity of Ag cations and allow linear potentiation/depression in tandem with a large conductance range (~244) and long data retention (~99% at 1 hour). Moreover, according to the reduction potentials of incorporated metals (Pt, Ta, W, and Ti), the extent of linearity improvement is selectively tuneable. Image processing simulation proves that the Ti4.8%:a-Si device can fully function with high accuracy as an ideal synaptic model.


Assuntos
Engenharia , Metais , Ligas , Simulação por Computador , Oxirredução
16.
Sci Rep ; 12(1): 11874, 2022 Jul 13.
Artigo em Inglês | MEDLINE | ID: mdl-35831317

RESUMO

Ti and its alloys are the most used metallic biomaterials devices due to their excellent combination of chemical and mechanical properties, biocompatibility, and non-toxicity to the human body. However, the current alloys available still have several issues, such as cytotoxicity of Al and V and high elastic modulus values, compared to human bone. ß-type alloys, compared to α-type and (α + ß)-type Ti alloys, have lower elastic modulus and higher mechanical strength. Then, new biomedical ß-type alloys are being developed with non-cytotoxic alloying elements, such as Mo and Nb. Therefore, Ti-5Mo-xNb system alloys were prepared by argon arc melting. Chemical composition was evaluated by EDS analysis, and the density measurements were performed by Archimedes' method. The structure and microstructure of the alloys were obtained by X-ray diffraction and optical and scanning electron microscopy. Microhardness values were analyzed, and MTT and crystal violet tests were performed to assess their cytotoxicity. As the Nb concentration increases, the presence of the ß-Ti phase also grows, with the Ti-5Mo-30Nb alloy presenting a single ß-Ti phase. In contrast, the microhardness of the alloys decreases with the addition of Nb, except the Ti-5Mo-10Nb alloy, which has its microhardness increased probably due to the ω phase precipitation. Biological in-vitro tests showed that the alloys are not cytotoxic.


Assuntos
Ligas , Nióbio , Ligas/química , Materiais Biocompatíveis/química , Módulo de Elasticidade , Humanos , Teste de Materiais , Nióbio/química , Titânio/química , Difração de Raios X
17.
J Phys Chem Lett ; 13(27): 6316-6322, 2022 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-35792939

RESUMO

Dicarbonyl species are ubiquitous on Rh/oxide catalysts and are known to form on Rh+ centers. However, dicarbonyl species have never been directly observed on single-atom alloys (SAAs) where the active site is metallic. Herein, using surface science and theoretical modeling, we provide evidence of dicarbonyl species at isolated Rh sites on a RhCu(100) SAA. This approach not only enables us to directly visualize dicarbonyl species at Rh sites but also demonstrates that the transition between the mono- and dicarbonyl configuration can be achieved by changing surface temperature and CO pressure. Density functional theory calculations further support the mono- and dicarbonyl assignments and provide evidence that these species should be stable on other SAA combinations. Together, these results provide a picture of the structure and energetics of both the mono- and dicarbonyl configurations on the RhCu(100) SAA surface and should aid with IR assignments on SAA nanoparticle catalysts.


Assuntos
Ligas , Catálise
18.
Sensors (Basel) ; 22(13)2022 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-35808360

RESUMO

This paper mainly focuses on various types of robots driven or actuated by shape memory alloy (SMA) element in the last decade which has created the potential functionality of SMA in robotics technology, that is classified and discussed. The wide spectrum of increasing use of SMA in the development of robotic systems is due to the increase in the knowledge of handling its functional characteristics such as large actuating force, shape memory effect, and super-elasticity features. These inherent characteristics of SMA can make robotic systems small, flexible, and soft with multi-functions to exhibit different types of moving mechanisms. This article comprehensively investigates three subsections on soft and flexible robots, driving or activating mechanisms, and artificial muscles. Each section provides an insight into literature arranged in chronological order and each piece of literature will be presented with details on its configuration, control, and application.


Assuntos
Robótica , Ligas , Fenômenos Mecânicos , Músculos , Ligas de Memória da Forma
19.
J Mech Behav Biomed Mater ; 133: 105358, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35834894

RESUMO

In view of the urgent demands of shape memory alloys (SMAs) for biomedical applications due to the world population aging issue, the mechanical properties and functionalities of the biocompatible Ti-Au-Cr-based SMAs, which are tailored by Ta additions, have been developed in this study. The quaternary SMAs were successfully manufactured by physical metallurgy techniques and their mechanical properties and functionalities were examined. In the continuous tensile tests, it was found that the correlation between the yielding strength and phase stability followed a typical trend of mechanical behavior of SMAs, showing the lowest yielding strength at the metastable ß-parent phase. Functional mappings between the alloy strength and elongation revealed that compared to the Ta-free specimen, the ductility was promoted 50% while the strength remained intact through the 4 at.% introduction of Ta. Slight shape recovery was observed in the cyclic loading-unloading tensile tests during the unloading process and the highest shape recovery was found in the Ti-4 at.% Au-5 at.% Cr-4 at.% Ta specimen. This indicates that the 4 at.% Ta tailored Ti-Au-Cr SMAs could be a promising material for biomedical applications.


Assuntos
Ligas de Memória da Forma , Titânio , Ligas , Materiais Biocompatíveis , Teste de Materiais , Metalurgia , Resistência à Tração
20.
J Mech Behav Biomed Mater ; 133: 105360, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35839635

RESUMO

Strengthening of biomedical Co-Cr-Mo alloys has been explored via thermomechanical processing for enhancing the durability of their biomedical applications. However, the effects of cold and hot deformation on the cellular activity continue to be unclear. In this study, we prepared Co-Cr-Mo alloy rods via cold swaging and hot-caliber rolling and studied the relationship between the microstructure and cellular response of pre-osteoblasts. The cold-swaged rod experienced strain-induced martensitic transformation, which increased the volume fraction of the hexagonal close-packed (hcp) ε-martensite to ∼60 vol.% with an increase in area reduction (r) to 30%. The 111γ fiber texture of the face-centered cubic (fcc) γ-matrix followed the Shoji-Nishiyama orientation relationship with ε-martensite. Cell culture results revealed beneficial effects of cold swaging on the cell response, in terms of adhesion, proliferation and morphology of cells, although increasing r did not significantly affect cellular metabolism levels. The addition of small content of Zr (0.04 wt.%) led to enhanced focal adhesion of cells, which became more significant at higher r. The microstructural evolution during hot-caliber rolling, namely, grain refinement without any phase transformation and strong texture development, did not appreciably affect the cellular activity. These findings are envisaged to facilitate alloy design and microstructural optimization for favorable tuning the osseointegration of biomedical Co-Cr-Mo alloys.


Assuntos
Ligas , Materiais Biocompatíveis , Ligas/química , Materiais Biocompatíveis/química , Materiais Biocompatíveis/farmacologia , Teste de Materiais
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