Titanium and Ti-13Nb-13Zr Alloy Porous Implants Obtained by Space-Holder Technique with Addition of Albumin

2012 ◽  
Vol 529-530 ◽  
pp. 574-579
Author(s):  
Tamiye Simone Goia ◽  
Kalan Bastos Violin ◽  
José Carlos Bressiani ◽  
Ana Helena de Almeida Bressiani
Keyword(s):  
Thermal Treatment ◽  
Surface Characterization ◽  
High Vacuum ◽  
Pure Titanium ◽  
Vacuum Furnace ◽  
Metal Powders ◽  
Space Holder ◽  
Significant Difference ◽  
13Zr Alloy ◽  
Hydride Titanium

Titanium and its alloys are the main metals studied as porous metallic implants by their excellent mechanical properties and biological interactions. Production methods of porous metallic materials are based on powder metallurgy (PM), because it allows the manufacturing of parts with complex shapes and dimensions close to the finals (near-net shape), and the addition of alloying elements reaching a satisfactory structural homogeneity, and porosity. The pore production by space-holder technique constitutes of mixing organic compounds with metal powder, which when removed by thermal treatment prior structures are kept in place. The objective of this study is to obtain porous implants of commercially pure titanium (cpTi) and Ti-13Nb-13Zr alloy by PM with space-holder technique and albumin as an additive. For the processing of the samples were used hydride titanium powder (TiH2) to obtain cpTi samples, and metal powders of Ti, Nb and Zr in the stoichiometric proportions for obtaining the alloy samples. The samples were prepared by mixing the metallic powder to the albumin (30wt%) and filling a silicone model that was pressed isostatically (140 MPa). The thermal treatment was performed in an oxidizing atmosphere (350°C/1h) for the decomposition of organic material. The sintering was performed at a temperature of 1300°C (1h/cpTi, 3h/Alloy) in high vacuum furnace (10-5 mBar) to all samples. The calculated porosity showed a significant difference between the samples cpTi (40%) and alloy (60%). The samples surface characterization showed very rough with high specific surface area. Samples of cpTi presented formation of necks arising from sintering. In the alloy samples were observed homogenous microstructure with the presence of α and β phases composing the Widmanstätten structure. It is possible to conclude that the same amount albumin allowed the formation of pores in the microstructure of cpTi and alloy although in different proportions, without harming the sintering of both and allowing diffusion of the alloy elements.

Characterization of Ti-27Nb-13Zr Alloy Produced by Powder Metallurgy

2012 ◽  
Vol 77 ◽  
pp. 178-183
Author(s):  
Marcio W.D. Mendes ◽  
Ana Helena Almeida Bressiani ◽  
José Carlos Bressiani
Keyword(s):  
Elastic Modulus ◽  
Powder Metallurgy ◽  
Vickers Hardness ◽  
High Vacuum ◽  
High Strength ◽  
Hardness Test ◽  
High Energy ◽  
Vacuum Furnace ◽  
Mean Values ◽  
13Zr Alloy

Titanium alloy are widely used in biomedical applications due to their excellent properties such as high strength, good corrosion resistance and excellent biocompatibility. Researches are being developed with elements such as Nb and Zr that reach all criterions for excellent biocompatibility and provide titanium alloys with Young’s modulus close to human bone. The aim of this work was to produce Ti-27Nb-13Zr alloy with different milling times by powder metallurgy process. The mixtures were performed by high energy milling and sintering in high vacuum furnace with temperature of 1300 °C / 3 h. The microstructures of samples were analyzed by SEM and XRD, while the mechanical behavior was evaluated by elastic modulus and Vickers hardness test. The diffraction results of sintering treatment indicate that the alloys are composed of α and β phases. Images obtained by SEM indicate the formation of equiaxial structures. Vickers hardness measurements from sintered samples with 1300 °C / 3 h indicate mean values around 413, 473 and 609 HV for 2, 6 and 10 hours of milling, respectively. The values of elastic modulus enable use the alloy as biomaterial.

Design, Processing and Characterization of Materials with Controlled Radial Porosity for Biomedical and Nuclear Applications

2016 ◽  
Vol 704 ◽  
pp. 325-333 ◽  
Author(s):  
Paloma Trueba ◽  
Ernesto Chicardi ◽  
José Antonio Rodríguez-Ortiz ◽  
Juan José Pavón ◽  
Joaquín Cobos ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Compaction Pressure ◽  
High Vacuum ◽  
Pure Titanium ◽  
Processing Conditions ◽  
Commercially Pure Titanium ◽  
Space Holder ◽  
New Device ◽  
Cp Ti ◽  
Nuclear Applications

The manufacture of graded materials has gained an enormous interest during the last decade due to the diversity of industrial and biological materials systems that require or are actually designed to implement that criterion; those natural or artificial materials offer multiple possibilities of applications. In this work, a novel uniaxial and sequential compaction device has been successfully designed and fabricated, in order to obtain samples with three different layers; this new device is suitable for both conventional and non-conventional powder metallurgy (PM) techniques. In addition, this device allowed us to use different combinations of powders and space-holder particles, irrespective of their nature, sizes, morphologies and proportions. It has no restriction about applying different compaction pressures for every layer, which may result in increasing or decreasing porosity. This compaction device is especially powerful if the aim is obtaining samples with radial graded porosity for biomedical applications (replacement of cortical bone involved in different joints and dental restorations) and nuclear applications (mimicking burnt used nuclear fuel). Specifically in this work, different samples with radial graded porosity were fabricated and then microstructurally and mechanically characterized: i) Commercially pure titanium (CP Ti) samples, starting from blends CP Ti with 20 vol.%, 40 vol.% and 60 vol.% of Sodium Chloride (NaCl) as space holder, which were placed in core, intermediate and external layers, respectively; processing conditions were 800 MPa of compaction pressure and 1250 °C for 2h in high vacuum of sintering; and ii) CeO2 samples, starting from blends CeO2 with 0.5 vol.%, 3.0 vol.% and 7.5 vol.% of Ethylene Bis Stearamide (EBS) as space holder, which were placed in core, intermediate and external layers, respectively; processing conditions were 460 MPa in external layer and 700 MPa in core and intermediate layers of compaction pressure, and 1700 °C during 4h in static air of sintering. This new device has proved to have unique advantages for solving problems of structural integrity in conventional PM manufacturing in a simple, economic and reproducible way.

scholarly journals Influence of the Thermal Treatment to Address a Better Osseointegration of Ti6Al4V Dental Implants: Histological and Histomorphometrical Study in a Rabbit Model

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Antonio Scarano ◽  
Ezio Crocetta ◽  
Alessandro Quaranta ◽  
Felice Lorusso
Keyword(s):  
Thermal Treatment ◽  
Dental Implants ◽  
Bone Healing ◽  
Rabbit Model ◽  
Titanium Implants ◽  
Control Group ◽  
Left Femur ◽  
Bone Response ◽  
First Choice ◽  
Significant Difference

Background. Pure titanium continues to be the first choice for dental implants and represents the gold standard for their biocompatibility and physical and mechanical characteristics, while the titanium alloy (Ti6Al4V) has good mechanical properties. The surface structure of the titanium oxide layer formation on the surface influences and improves the bone response around dental implants. Purpose. The purpose of this study is to evaluate the influence of a thermal treatment of Ti6Al4V implant surfaces and the bone healing response in a rabbit model. Methods. Altogether sixteen implants with same design were inserted into the distal femoral metaphysis. A screw (13 mm long, 4 mm in diameter) was inserted in an implant bed. Each rabbit received two implants, one in the left femur and one in the right femur. The samples were histologically and histomorphometrically evaluated at 8 weeks. Results. A statistically significant difference (p = 0.000034) was present histologically in the percentages of bone-implant contact (BIC) between the test group (BIC = 69.25±4.49%.) and control group (BIC = 56.25 ± 4.8%) by one-way analysis of variance (ANOVA). Significance was set at p ≤ 0.05. Conclusions. The outcome of the present study indicates a novel approach to improving bone healing around titanium implants.

Survival of Xanthoria parietina in simulated space conditions: spectroscopic analysis and vitality assessment

2021 ◽  
Author(s):  
Christian Lorenz ◽  
Renato Benesperi ◽  
Elisabetta Bianchi ◽  
Stefano Loppi ◽  
Alessio Papini ◽  
...  
Keyword(s):  
Uv Radiation ◽  
Spectral Band ◽  
High Vacuum ◽  
Photosynthetic Apparatus ◽  
Space Radiation ◽  
Adaptive Plasticity ◽  
Cotton Cloth ◽  
Extreme Conditions ◽  
Significant Difference ◽  
Xanthoria Parietina

<p>One of the main topics of astrobiology is the study of life limits in stressful environments. This field of research has the aim to understand the physiological and biochemical effects on unprotected biological samples in extreme conditions, such as space. Moreover, these studies provide indications about organisms’ adaptive plasticity under a climate change perspective, the terrestrial geological past and future scenarios, as well as extra-terrestrial habitats as Mars surface.</p> <p>The biological specimen chosen for this study was <em>Xanthoria parietina </em>(L.) Th. Fr. It is a widespread foliose lichen growing on bark and rocks which has a broad spectrum of tolerance to air pollutants such as NO<sub>X</sub> and heavy metals, and resistance to UV-radiation because of the screening properties provided by the secondary metabolism product parietin. In this study we evaluated the ability of this lichen specie to survive under simulated UV space radiation in two different extreme environments i.e., in N<sub>2</sub> atmosphere (N<sub>2</sub>) and in vacuum (10<sup>0</sup>~10<sup>-2</sup> Pa) (VAC).</p> <p>Thalli of <em>X. parietina </em>were randomly collected in a remote area of Tuscany, Italy in June and July 2020. Thalli were dehydrated for 24 h at room temperature (25°C) and stored at -18°C until treatment. Three days before the treatment, thalli were allowed to recover their normal metabolic conditions in a growth chamber at 25 °C and 70 μmol m<sup>-2</sup> s<sup>-1</sup> PAR photons. Overnight, thalli were covered with a black cotton cloth and kept moistened by spraying with distilled water.</p> <p>The simulated UV space radiation was produced using a Xe-enhanced UV lamp with a sun-like emission spectrum (wavelength range 185-2000 nm). The aforementioned atmospheric conditions (N<sub>2</sub> and VAC) were chosen to set up an extreme and dehydrating environment for the lichen. The total absorbed UV radiation dose was 1.34 MJ m<sup>-2</sup> for each exposed sample. During the irradiation, the IR reflectance spectrum of the lichen was monitored <em>in situ</em> with infrared spectroscopy to assess changes in spectral bands.</p> <p>The efficiency of the photosynthetic apparatus was assessed as indicator of vitality, and was expressed in terms of chlorophyll <em>a</em> fluorescence (F<sub>V</sub>/F<sub>M</sub>) and Normalized Difference Vegetation Index (NDVI). The examination of <em>X. parietina</em> recovery through eco-physiological analysis revealed the capacity of this lichen species to survive in extreme conditions such as those simulated in this investigation. It has been highlighted the significant difference between treatments about the photosynthetic efficiency parameters recovery trends, finding that UV-radiation in vacuum produces more intense effects on F<sub>V</sub>/F<sub>M</sub> values. After 72h, UV N<sub>2</sub> fluorescence mean values recovered up to 93% of the starting ones, while UV VAC fluorescence recovered up to 45% of the pre-exposure values. The IR analysis revealed several spectral band changes in the fingerprint region. The most visible variation was the 5200 cm<sup>-1</sup> water band, disappearing in the overtone region. This analysis suggests that the disappearance of H<sub>2</sub>O band after treatment is strictly linked to the thalli dehydration due to the atmospheric simulated conditions represented by N<sub>2</sub> insufflation and high vacuum application. Nevertheless, <em>X. parietina</em> was able to survive to UV-radiation in N<sub>2</sub> atmosphere and in vacuum, and for this reason it may be considered a candidate for further evaluations on its survival capacity in extreme conditions.</p>

scholarly journals Effect of Yd:YAG laser irradiation on the shear bond strength of orthodontic metal brackets

2020 ◽  
Vol 25 (1) ◽  
pp. 28-35
Author(s):  
Fernando César Moreira ◽  
Helder Baldi Jacob ◽  
Luis Geraldo Vaz ◽  
Antonio Carlos Guastaldi
Keyword(s):  
Bond Strength ◽  
Laser Irradiation ◽  
Shear Bond Strength ◽  
Surface Characterization ◽  
Test Machine ◽  
Base Surface ◽  
Bonding Failure ◽  
Significant Difference ◽  
Chi Square Analysis ◽  
Bracket Base

ABSTRACT Objective: The purpose of this study was to evaluate the effect of the Yd:YAG laser irradiation on orthodontic bracket base surface. Shear bond strength (SBS) values and sites of the bonding failure interfaces were quantified. Methods: Brackets were divided into two groups: OP (One Piece - integral sandblast base) and OPL (One Piece - laser irradiation). The brackets were randomly bonded on an intact enamel surface of 40 bovine incisors. The SBS tests were carry out using a universal test machine. A stereomicroscopy was used to evaluate the adhesive remnant index (ARI), and surface characterization was performed by scanning electron microscopy (SEM). Student’s t-test was used to compare the SBS between the two groups (p< 0.05). Frequencies and chi-square analysis were applied to evaluate the ARI scores. Results: OPL group showed higher value (p< 0.001) of SBS than OP group (43.95 MPa and 34.81 MPa, respectively). ARI showed significant difference (p< 0.001) between OPL group (ARI 0 = 100%) and OP group (ARI 0 = 15%). SEM showed a higher affinity between the adhesive and the irradiated laser base surface. Conclusions: Yd:YAG laser irradiation on bracket base increased SBS values, showing that bonding failure occurs at the enamel/adhesive interface. Laser-etched bracket base may be used instead of conventional bases in cases where higher adhesion is required, reducing bracket-bonding failure.

Synthesis of powder metallurgy Ti-3Fe-2Al alloy using high-frequency induction heating

2019 ◽  
Vol 34 (01n03) ◽  
pp. 2040031
Author(s):  
Stella Raynova ◽  
Khaled Alsharedah ◽  
Fei Yang ◽  
Leandro Bolzoni
Keyword(s):  
Mechanical Properties ◽  
Powder Metallurgy ◽  
Induction Heating ◽  
High Frequency ◽  
High Efficiency ◽  
High Vacuum ◽  
Residual Porosity ◽  
Effect Of Temperature ◽  
Vacuum Furnace ◽  
High Frequency Induction

A powder metallurgy approach was applied for the synthesis of an [Formula: see text] Ti-2Al-3Fe alloy. Blends of the elemental Ti, Al and Fe powders were compacted and subsequently sintered. High-frequency induction heating (HFIH) instead of conventional high-vacuum furnace heating was used for the sintering, due to its high efficiency. The effect of temperature on the level of densification, residual porosity and mechanical properties was studied. Electron dispersive spectrum analysis was used to study the dissolution and homogenization of the alloying elements. The results showed that a short induction sintering (IS) cycle in the range of 10–15 min is sufficient to achieve significant powder consolidation, evident by the increase of the density and mechanical properties. The residual porosity diminishes with the increase of the sintering temperature. Full dissolution of the alloying powders is completed after sintering at temperatures above those of [Formula: see text]- to [Formula: see text]-phase transformation.

scholarly journals Facile Synthesis and Surface Characterization of Titania-Incorporated Mesoporous Organosilica Materials

2019 ◽  
Vol 3 (3) ◽  
pp. 77
Author(s):  
Chamila Gunathilake ◽  
Chandrakantha Kalpage ◽  
Murthi Kadanapitiye ◽  
Rohan S. Dassanayake ◽  
Amanpreet S. Manchanda ◽  
...  
Keyword(s):  
Thermal Treatment ◽  
Triblock Copolymer ◽  
Surface Characterization ◽  
Titanium Isopropoxide ◽  
Ethanol Solution ◽  
Molar Ratio ◽  
Initial Reaction ◽  
Pluronic P123 ◽  
Synthesis Strategy ◽  
Bridging Groups

Titania-incorporated organosilica-mesostructures (Ti-MO) were synthesized using tris [3-(trimethoxysilyl)propyl]isocyanurate, tetraethylorthosilicate as silica precursors, and titanium isopropoxide as the titanium precursor via a co-condensation method in the presence of the triblock copolymer, Pluronic P123. The triblock copolymer was completely removed by extraction with a 95% ethanol solution, followed by a thermal treatment at 350 °C under flowing nitrogen without decomposing isocyanurate bridging groups. The molar ratio of titanium to silica in the mesostructures was gradually changed by increasing the amount of tetraethylorthosilicate in the initial reaction mixture. Our synthesis strategy also allowed us to tailor both adsorption and structural properties, including a well-developed specific surface area, high microporosity, and large pore volume. A portion of the samples was thermally treated at 600 °C to remove both the block copolymer and bridging groups. The thermal treatment at 600 °C was used to convert the amorphous titania into a crystalline anatase form. The Ti-MO materials were characterized using a N2 adsorption desorption analysis, thermogravimetric analysis (TGA), solid state nuclear magnetic resonance (NMR), transmission electron microscope (TEM), and X-ray powder diffraction (XRD). CO2 adsorption studies were also conducted to determine the basicity of the Ti-MO materials. The effect of the surface properties on the CO2 sorption was also identified.

scholarly journals Effect of Stress Ratio and Notch on Fatigue Strength of Commercial Pure Titanium

2020 ◽  
Vol 321 ◽  
pp. 11012
Author(s):  
IWATA Toshiaki
Keyword(s):  
Fatigue Strength ◽  
Fatigue Limit ◽  
Pure Titanium ◽  
Longitudinal Direction ◽  
Structural Members ◽  
Application Range ◽  
Seawater Corrosion ◽  
Significant Difference ◽  
Safe Side ◽  
Cp Ti

Titanium alloys such as Ti-6Al-4V are widely used in the aerospace domain worldwide; consequently, they have been extensively investigated, and the accumulated data has facilitated their use in the construction of structural members. In contrast, commercial pure (CP) Ti, which is cheaper than Ti alloys is widely used in the general industry, especially in the marine domain in Japan because it exhibits superior seawater corrosion resistance and biocompatibility. However, CP titanium has a strong anisotropy and consists of an hcp crystal structure; therefore, the strength data are insufficient owing to its short use history as a structural material, and some of its mechanical material properties remain unclear. Herein, the effect of mean stress and stress concentration on the fatigue strength of CP Grade 2 titanium was evaluated for the application range expansion of CP titanium. The results indicated that the fatigue limit in the longitudinal direction was 80–84% that in the transverse direction for smooth specimens. However, no significant difference was noted in the fatigue limit in both the directions for notched specimens. Furthermore, it was noted that it is necessary to apply at least Sa-0.5Su line to design the safe side in CP Grade 2 titanium.

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