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Journal of Colloid and Interface Science Apr 2017Nanoporous (NP) PdCu alloy is easily fabricated by dealloying PdCuAl ternary alloy in dilute sulfuric acid. Selectively dissolving Al from PdCuAl alloy generates the...
Nanoporous (NP) PdCu alloy is easily fabricated by dealloying PdCuAl ternary alloy in dilute sulfuric acid. Selectively dissolving Al from PdCuAl alloy generates the three-dimensional uniform nanosponge architecture with narrow ligament size distribution. Benefitting from the unique nanoporous architecture and the alloying effect, the as-made NP-PdCu exhibits outstanding sensing performance towards the detection of hydrogen peroxide (HO) and glucose. Compared with NP-Pd and commercial Pd/C catalysts, the NP-PdCu alloy presents high sensitivity, wide linear range of 0.1-2.0mM, low detection limit of 2.1μM, and long-term stability toward HO detection. In addition, the NP-PdCu can efficiently detect glucose in a wide concentration range (1-30mM) with the low detection limit of 1.9μM. Moreover, the NP-PdCu exhibits good anti-interference toward ascorbic acid, uric acid, and dopamine. Characterized by easy preparation, unique electrocatalytic activity, and high structure stability, the NP-PdCu alloy possesses great application prospect to construct platform for electrochemical sensing.
Topics: Alloys; Copper; Electrochemical Techniques; Glucose; Hydrogen Peroxide; Nanoparticles; Palladium; Particle Size; Porosity; Surface Properties
PubMed: 28049057
DOI: 10.1016/j.jcis.2016.12.041 -
Materials Science & Engineering. C,... Nov 2015To increase an orthopedic implant's lifetime, researchers are now concerned on the development of new titanium alloys with suitable mechanical properties (low elastic...
To increase an orthopedic implant's lifetime, researchers are now concerned on the development of new titanium alloys with suitable mechanical properties (low elastic modulus-high fatigue strength), corrosion resistance and good workability. Corrosion resistance of the newly developed titanium alloys should be comparable with that of pure titanium. The effect of medical preparations containing fluoride ions represents a specific problem related to the use of titanium based materials in dentistry. The aim of this study was to determine the corrosion behavior of β titanium alloy Ti-39Nb in physiological saline solution and in physiological solution containing fluoride ions. Corrosion behavior was studied using standard electrochemical techniques and X-ray photoelectron spectroscopy. It was found that corrosion properties of the studied alloy were comparable with the properties of titanium grade 2. The passive layer was based on the oxides of titanium and niobium in several oxidation states. Alloying with niobium, which was the important part of the alloy passive layer, resulted in no significant changes of corrosion behavior. In the presence of fluoride ions, the corrosion resistance was higher than the resistance of titanium.
Topics: Alloys; Corrosion; Dental Implants; Dentistry; Materials Testing
PubMed: 26249624
DOI: 10.1016/j.msec.2015.07.029 -
American Journal of Orthodontics Feb 1980Historically, few alloys have been used in the fabrication of orthodontic appliances. This article reviews the gold-based, stainless steel, chrome-cobalt-nickel, and... (Comparative Study)
Comparative Study
Historically, few alloys have been used in the fabrication of orthodontic appliances. This article reviews the gold-based, stainless steel, chrome-cobalt-nickel, and nitinol alloys, as well as beta titanium, a new material for orthodontics. Mechanical properties and manipulative characteristics are summarized to develop a basis for the selection of the proper alloy for a given clinical situation. The beta titanium wire has a unique balance of low stiffness, high springback, formability, and weldability which indicates its use in a wide range of clinical applications. A number of such applications are described.
Topics: Alloys; Chemical Phenomena; Chemistry, Physical; Chromium Alloys; Dental Alloys; Elasticity; Gold Alloys; Nickel; Orthodontic Appliances; Stainless Steel; Tensile Strength; Titanium; Tooth Movement Techniques
PubMed: 6928342
DOI: 10.1016/0002-9416(80)90001-9 -
Materials Science & Engineering. C,... Dec 2020Zinc is a biodegradable metal, which exhibits more moderate biodegradability than magnesium and iron, so that it has great application potential in the field of...
Zinc is a biodegradable metal, which exhibits more moderate biodegradability than magnesium and iron, so that it has great application potential in the field of biomedical materials. Alloying of zinc and iron may lead to producing a new type of implant material Zn-Fe alloy, which might be able to meet the requirements for a moderate degradation rate. However, due to the huge difference in the melting point between zinc and iron, the preparation of Zn-Fe alloy is quite challenging and hence rarely reported. In this study, we show that Zn-Fe alloys can be successfully prepared by electrodeposition technology. The microstructures, composition, degradation properties and biocompatibility of the Zn-Fe alloys were systematically studied. The results showed that the content of iron in the alloys ranged from 0 to 8 wt%, depending on the concentration of Fe ions and the current density. In the alloys, the major's phases were η, δ and Г, and they were mainly affected by the ion concentration in the electrolyte. In the in vitro immersion tests, the Zn-Fe alloy ZF2-1 showed the highest immersion corrosion rate, while ZF3-1 showed the highest electrochemical corrosion rate. Moreover, we found that the corrosion rates of the alloys were significantly higher than that of the pure Fe. In the in vivo experiments, we confirmed that the Zn-Fe alloy possessed good biocompatibility. These results demonstrate that the electrodeposition technology is a good method to prepare Zn-Fe alloys, and the Zn-Fe alloys prepared by this method are potentially promising materials for biomedical applications.
Topics: Absorbable Implants; Alloys; Biocompatible Materials; Corrosion; Electroplating; Magnesium; Materials Testing; Zinc
PubMed: 32919656
DOI: 10.1016/j.msec.2020.111295 -
Acta Biomaterialia Oct 2019Microstructural refinement of magnesium (Mg) alloys is beneficial for mechanical and corrosion properties, both of which are critical for their successful application as...
Microstructural refinement of magnesium (Mg) alloys is beneficial for mechanical and corrosion properties, both of which are critical for their successful application as temporary implant materials. One method of achieving a refined microstructure is through rapid solidification via gas-atomization-powder production. In this study we investigated spark plasma sintering (SPS) as a potential processing method for maintaining this refined microstructure while achieving a range of porosities up to full densification. We characterized the microstructural evolution as a function of sintering temperature from 250 to 450 °C for the alloy WE43 using multi-scale correlative microscopy techniques, including light microscopy and scanning and transmission electron microscopy-based methods. The spatial distribution of the two major alloying elements, neodymium (Nd) and yttrium (Y), was determined and the intermetallic phases they form identified using energy dispersive X-ray spectroscopy in conjunction with electron diffraction. The gas-atomized powder microstructure consists of Mg-rich dendrites and a percolating interdendritic Mg-Nd-Y ternary phase with structure MgNdY, surrounded by a high Nd and Y content in solid solution. This microstructure is maintained up to a sintering temperature of 350 °C, while with higher sintering temperatures segregation of Nd and Y dominates. The percolating ternary phase breaks up into faceted globular precipitates with structure MgNd, which is isomorphous to MgNdY. Y comes out of solution and migrates to previous powder-particle surfaces, possibly forming YO. Sample densities ranged from 64 to 100% for sintering temperatures of 250 to 450 °C, respectively, and the grain size remained constant at about 10 µm. SPS is demonstrated to be an attractive alternative method for processing Mg alloys to a wide range of porosities and fine microstructures. The microstructural refinement achieved by SPS holds the potential for slow and homogeneous corrosion. STATEMENT OF SIGNIFICANCE: This study presents the impact spark plasma sintering (SPS) has on the microstructure of WE43, a magnesium alloy used for biodegradable implants. SPS is of great interest in this context as it is scalable, rapid, and has the potential for tuning density while maintaining a refined microstructure. The microstructure and density are explored from the gas-atomized powder to the densified material using electron microscopy and chemical mapping from the macro- to the nano-level. The insights gained reveal an original evolution of rare-earth element distribution with an isomorphous chemistry change, while the microstructure develops from the non-equilibrium state (powder) towards an equilibrium structure upon sintering. This study, including measurements of mechanical performance, sets the premises of SPS for the fabrication of Mg-based implants with tunable characteristics.
Topics: Alloys; Biocompatible Materials; Electrons; Hardness; Magnesium; Materials Testing; Plasma Gases; X-Ray Diffraction
PubMed: 31254685
DOI: 10.1016/j.actbio.2019.06.045 -
Acta Biomaterialia Apr 2020Microstructural design was a long-term sustainable development method to improve the biodegradability and mechanical properties of low alloyed biomedical Mg alloys. In...
Microstructural design was a long-term sustainable development method to improve the biodegradability and mechanical properties of low alloyed biomedical Mg alloys. In this study, the microstructural features (including grain size, deformation twin, deformed grains, sub-grains, and recrystallized grains) of the MZ2 ((Mg-2Zn (wt%)) alloy were controlled by different single-passed rolling reductions at high temperature. Besides the effect of grain size, we found that deformation twins and deformed grains influenced corrosion performance. Grain refinement with uniform distribution, meanwhile reducing the content of deformation twins, deformed grains, and sub-grains, was a practical method to improve both corrosion resistance and mechanical properties of MZ2 alloy. This finding proposed a better understanding of the development of lean biomedical Mg alloys with superior mechanical properties and favorable corrosion resistance. STATEMENT OF SIGNIFICANCE: Current research and development of biomedical Mg focused on alloying methods. The lean biodegradable Mg, which reduced the materials' compositional complexity, was the benefit of development for long-term sustainability. Here, our work revealed the relationship between microstructural features and corrosion resistance of a lean Mg-2Zn alloy during the different single-passed rolling processes. We found that recrystallized fine grains with partially ultra-fine grains could improve both strength and corrosion resistance. This study could give a new understanding of the development of lean biodegradable Mg alloys by using microstructural design to improve the overall performance of biomedical applications.
Topics: Alloys; Animals; Biocompatible Materials; Cell Line; Hot Temperature; Magnesium; Materials Testing; Mice; Oxidation-Reduction; Particle Size; Tensile Strength; Zinc
PubMed: 32126309
DOI: 10.1016/j.actbio.2020.02.040 -
Environmental Science & Technology Feb 2023Electrocatalytic ammonia (NH) synthesis from the reduction of nitrate (NO) is one of the effective and mild methods to treat nitrogen-containing wastewater from...
Electrocatalytic ammonia (NH) synthesis from the reduction of nitrate (NO) is one of the effective and mild methods to treat nitrogen-containing wastewater from stationary sources and to obtain NH readily compared with the Haber-Bosch process. However, the low efficiency of electrocatalytic NO reduction to NH on traditional Cu-based catalysts hinders their practical application. Here, we prepare a Au/Cu single atom (SA) alloy (Au/Cu SAA) that shows a high performance of NH synthesis with 99.69% Faradaic efficiency at -0.80 V vs RHE. The structures of Au SAs and alloyed Au/Cu are confirmed by the detailed characterizations. Online differential electrochemical mass spectrometry confirms the occurrence of key reaction intermediates (*NO, *NO, and *NH). Density functional theory calculations demonstrate that Au SAs efficiently reduce the adsorption energy of *NO, and the newly formed Au-Cu bonds boost the reduction process of *NO to *NO. Meanwhile, Au/Cu SAAs produce significantly less N and NO byproducts due to the prohibition of N-N coupling on single atoms, which finally leads to excellent Faradaic efficiency and NH selectivity.
Topics: Nitrates; Ammonia; Nitrogen Dioxide; Adsorption; Alloys
PubMed: 36785514
DOI: 10.1021/acs.est.2c07968 -
International Journal of Molecular... Feb 2012The neotype magnesium alloy, Mg-Nd-Zn-Zr (NZK) alloy, was implanted into the rabbit femur to investigate its in vivo degradation behavior and biocompatibility....
The neotype magnesium alloy, Mg-Nd-Zn-Zr (NZK) alloy, was implanted into the rabbit femur to investigate its in vivo degradation behavior and biocompatibility. Seventy-two New Zealand white rabbits were randomly divided into the NZK alloy group, titanium alloy group and sham-operated group. Then NZK alloy rods were embedded in the rabbit femur in the NZK alloy group, titanium alloy rods were embedded in the titanium alloy group, and only bone tunnel was established in the sham-operated group. Prior to surgery and at 1, 7, 14, 28 and 56 days after operation, the serum alanine transaminase, creatinine, creatine kinase and magnesium ion concentration were examined in each group. An X-ray of the implanted region was taken at 7, 14, 28 and 56 days after implantation. The pathological changes in heart, liver, kidney and bone from the implant region were examined at 28 and 56 days postoperatively. The degradation behavior of the NZK alloy was observed using scanning electron microscope with an energy dispersive spectroscopy system. There were no significant differences in serum alanine transaminase, creatinine, creatine kinase and magnesium ion concentrations among each group at the same time point (P>0.05). The histology of heart, liver, kidney and bone from implant region was altered. The results demonstrate that the NZK alloy implanted into the rabbit femur could be absorbed gradually, and that the NZK alloy has excellent biocompatibility in vivo.
Topics: Alloys; Animals; Biocompatible Materials; Implants, Experimental; Magnesium; Rabbits; Serologic Tests; Time Factors; Titanium
PubMed: 22020557
DOI: 10.3892/ijmm.2011.815 -
Cardiovascular Engineering and... Dec 2016High entropy alloys (HEAs) are new class of metallic materials with five or more principal alloying elements. Due to this distinct concept of alloying, the HEAs exhibit...
High entropy alloys (HEAs) are new class of metallic materials with five or more principal alloying elements. Due to this distinct concept of alloying, the HEAs exhibit unique properties compared to conventional alloys. The outstanding properties of HEAs include increased strength, superior wear resistance, high temperature stability, increased fatigue properties, good corrosion, and oxidation resistance. Such characteristics of HEAs have generated significant interest among the scientific community. However, their applications are yet to be explored. This paper discusses the mechanical behavior and microstructure of AlCoCrFeNi HEA subjected to thermo-mechanical processing, and its potential application in peripheral vascular stent implants that are prone to high failure rates. Results show that AlCoCrFeNi alloy possesses characteristics that compare well against currently used stent materials and it can potentially find use in peripheral vascular stent implants and extend their life-cycle.
Topics: Alloys; Entropy; Finite Element Analysis; Materials Testing; Metals, Heavy; Spectrum Analysis; Stents
PubMed: 27848221
DOI: 10.1007/s13239-016-0286-6 -
Annals of Work Exposures and Health Jul 2020Nickel (Ni) and cobalt (Co) release from chromium-alloy powders (different stainless steels and a nickel-based Inconel alloy) compared with Ni and Co metal powders was...
Nickel (Ni) and cobalt (Co) release from chromium-alloy powders (different stainless steels and a nickel-based Inconel alloy) compared with Ni and Co metal powders was investigated at simulated human exposure scenarios (ingestion, skin contact, and inhalation) between 2 and 168 h. All investigated powders consisted of particles sized within the respirable range. The powder particles and their surface reactivity were studied by means of nitrogen adsorption and electrochemical, spectroscopic (X-ray photoelectron spectroscopy and atomic absorption spectroscopy), light scattering, and microscopic techniques. The release of both Ni and Co was highest in the acidic and complexing fluids simulating the gastric environment and an inhalation scenario of small powders (artificial lysosomal fluid). Relatively high corrosion resistance and lower levels of released Ni and Co were observed in all fluids for all alloy powders compared with the corresponding pure metals. The extent of released metals was low for powders with a passive surface oxide. This study strongly emphasizes the importance of considering alloying effects in toxicological classification and/or regulation of Ni and Co in alloys and metals.
Topics: Alloys; Cobalt; Humans; Nickel; Occupational Exposure; Powders; Surface Properties
PubMed: 32320011
DOI: 10.1093/annweh/wxaa042