Stiffness Tuning of NiTi Implants Through Aging

2016 ◽  
Author(s):  
Narges Shayesteh Moghaddam ◽  
Amirhesam Amerinatanzi ◽  
Soheil Saedi ◽  
Ali Sadi Turabi ◽  
Haluk Karaca ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Cortical Bone ◽  
Stress Shielding ◽  
Thermal Treatments ◽  
Metallic Implants ◽  
Treatment Conditions ◽  
Time Period ◽  
Aging Conditions ◽  
Superelastic Behavior ◽  
Low Stiffness

NiTi alloys are interesting materials for biomedical implants since they offer unique characteristics such as superelastic behavior, low stiffness (I.e., modulus of elasticity) close to that of the cortical bone, and shock absorption. Thermal treatments are the most common and practical ways to improve the superelasticity of these alloys. In addition to the superelastic behavior of the metallic implants, it is important for the implants to have a stiffness similar to that of cortical bone in order to reduce the risk of failure caused by stress shielding. The cortical bone has a stiffness ranging from 12 to 31 GPa for different patients (e.g., sex, age, mechanical behavior of bone) and various bone locations (e.g., jaw implant, hip implant), while the untreated Ni-rich NiTi has the stiffness equal to 41.37 GPa. One recently used technique to lower the stiffness of NiTi implant is to introduce porosity into the implant. The major problem associated with the imposed porosity is stress concentration on the pore walls and the subsequent implant failure. In this work, the purpose is to tune the stiffness via changing the post-heat treatment conditions, i.e., aging time and aging temperature. In this study, several bulk specimens of Ni-rich NiTi (SLM Ni50.8Ti49.2) were additively manufactured using selective laser melting (SLM) technique. The samples were solution annealed (950 °C, 5.5 h) and subsequently water quenched to provide equilibrium state in the samples. Subsequently, different aging conditions (350 °C and 450 °C for 5 to 18 hours) were applied to the samples. Mechanical testing (compression) was conducted on the samples and the stiffness of each sample was defined to investigate the effect of aging on the stiffness. Our results indicate that the range of 29.9 to 43.7 GPa for stiffness can be achieved through the implant via different time period and temperatures for aging. The modulus of 43.7 GPa is attributed to 10 hours heat treatment under 450 °C and the modulus of 29.9 GPa is attributed to 18 hours heat treatment under 350 °C.

Effect of Heat Treatment Conditions and Small Addition of Cu on Occurrence of Serration in Al-Si Alloys

2014 ◽  
Vol 783-786 ◽  
pp. 180-185
Author(s):  
Teruto Kanadani ◽  
Norihito Nagata ◽  
Keiyu Nakagawa ◽  
Koji Murakami ◽  
Makoto Hino
Keyword(s):  
Heat Treatment ◽  
Binary Alloy ◽  
Room Temperature ◽  
Small Addition ◽  
The Other ◽  
Aging Rate ◽  
Aging Period ◽  
Treatment Conditions ◽  
Heat Treated ◽  
Aging Conditions

In this study, the effect of heat treatment conditions and small addition of Cu on occurrence of serration in Al-Si alloys was investigated. Specimens were aged for various times up to 87ks at 273K or 473K after quenching from 853K, and tensile-tested at room temperature. In the binary alloy, serration was observed even after aging for 87ks at 273K, while in the case of aging at 473K, serration did not occur under aging conditions at aging time, tA≧20s. On the other hand, serration was observed even after aging for 72ks at 473K in the Cu-added alloy. In both alloys, serration was also recognized when the specimens were furnace-cooled from 853K to room temperature. Thus, for aging at 473K of the binary alloy serration was observed only when the aging period was short enough, but addition of Cu to the binary alloy prolonged the aging period where serration could be recognized. Aging rate of both alloys measured by tensile strength was almost the same. The size of precipitates in the Cu-added alloy was smaller than that in binary alloy. Moreover, the number of the precipitates at the grain boundary in the Cu-added alloy was smaller than that in the binary alloy. It is considered that serration occurs for Al-Si alloys when the specimen is heat-treated so that small precipitates may be formed. Now the details of the effect of Cu addition are not clear.

Thermomechanical Characterization of SMA Actuators Under Cyclic Loading

Aerospace ◽  
2003 ◽  
Author(s):  
Dimitris C. Lagoudas ◽  
Pavlin B. Entchev ◽  
Parikshith K. Kumar
Keyword(s):  
Heat Treatment ◽  
Cyclic Loading ◽  
Mechanical Loading ◽  
Large Diameter ◽  
High Energy ◽  
High Energy Density ◽  
Treatment Conditions ◽  
Loading Patterns ◽  
Superelastic Behavior ◽  
Different Diameters

Shape memory alloy (SMA) wire actuators have been increasingly used in various devices and applications due to their high energy density and simple design. With the use of these actuators the questions of size effects on their behavior need to be addressed. This paper presents a study on the cyclic loading behavior of large diameter SMA wires subjected to different thermo-mechanical loading paths. Wires of two different diameters are investigated in the current study—1.78 mm and 2.16 mm. The issues addressed in this work include the investigation and design of a gripping technique for the large diameter wires to avoid slippage and study of heat treatment conditions for optimized superelastic behavior. After the heat treatment, specimens are subjected to cyclic mechanical loading. Two different cyclic loading patterns have been investigated: loading up to a given value of stress or up to a given value of strain.

scholarly journals Effect of Heat Treatments on the Microstructural Evolution of a Single Crystal High-Entropy Superalloy

Metals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1600 ◽  
Author(s):  
Takuma Saito ◽  
Yung-Ta Chen ◽  
Yuji Takata ◽  
Kyoko Kawagishi ◽  
Wei-Che Hsu ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Microstructural Evolution ◽  
Solution Heat Treatment ◽  
Solution Treatment ◽  
Aging Treatment ◽  
Cast Sample ◽  
High Entropy ◽  
Treatment Conditions ◽  
Interdendrite Region ◽  
Aging Conditions

The effect of solution heat treatment as well as primary and secondary aging treatment conditions on the microstructural evolution of a high-entropy superalloy was investigated. The as-cast sample shows coarsened γ′ precipitates and other extra phases at interdendrite region due to microsegregation. This microsegregation makes γ′ solvus unclear and decreases the solidus. After conducting the solution treatment determined in this study, primary aging conditions showing an aligned cubic γ′ phase at 1050 °C for 4 h and random spherical γ′ precipitates at 950 °C for 20 h in similar size were found. By using both samples, secondary aging conditions showing coarsened secondary γ′ precipitates and γ particles inside the γ′ precipitates at 800 °C for 20 h and fine secondary γ′ precipitates at 850 and 870 °C for 20 h were found.

Improvement of the Reverse Characteristics of Ti/4H-SiC Schottky Barrier Diodes by Thermal Treatments

2007 ◽  
Vol 124-126 ◽  
pp. 105-108 ◽  
Author(s):  
Dae Hwan Kim ◽  
Jong Ho Lee ◽  
Jeong Hyun Moon ◽  
Myong Suk Oh ◽  
Ho Keun Song ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Thermal Treatment ◽  
Schottky Barrier ◽  
Breakdown Voltage ◽  
Schottky Barrier Height ◽  
Xrd Analysis ◽  
Silicide Phase ◽  
Thermal Treatments ◽  
Schottky Barrier Diodes ◽  
Treatment Conditions

Ti/4H-SiC Schottky barrier diodes were fabricated under 500, 750, 1000 °C thermal treatment conditions. After the heat treatment at 750 °C, formation of TiC(111) and Ti5Si3(210) phases was confirmed by XRD analysis. Formation of Ti carbide and silicide phase increased breakdown voltage VB from 545 V to 830 V. An improvement of breakdown voltage (VB) was observed in case of the thermal treatment in nitrogen ambient at 750 °C for 2 min. Ideality factor (n), specific on resistance (Ron), and Schottky barrier height (Φb) were 1.04, 2.7 m-cm2, 1.33 eV respectively.

scholarly journals THE STUDY OF ODOR PROFILE AND COLOR CHARACTERISTICS IN BEEF DURING HEAT TREATMENT

2018 ◽  
Vol 3 (4) ◽  
pp. 38-48 ◽  
Author(s):  
Zenon V. Lovkis ◽  
Irina M. Pochitskaya ◽  
Natallia V. Komarova
Keyword(s):  
Heat Treatment ◽  
Color Change ◽  
Heating Temperature ◽  
Ethyl Hexanoate ◽  
Odor Profile ◽  
Color Characteristics ◽  
Treatment Conditions ◽  
Time Period ◽  
Study Results ◽  
Maximum Heating Temperature

The article presents the study results of changes in the odor profile and color characteristics in beef under various heat treatment conditions. More than 120 volatile substances are identified. In samples subjected to short-term and minor heat treatment, 2-methyl-butene and ethyl hexanoate were found in significant amounts. In samples subjected to prolonged roasting at low temperature, as well as in samples subjected to processing at higher temperature for less time period, was found 3,5-dimethyl–4-octanone. Analysis of changes in color characteristics showed that increase in heating temperature results in significant darkening of the samples. The maximum heating temperature of 210 °C had the most significant effect on the color change. After heating for more than 30 minutes, carbonization of the samples occurred. The results indicate that controlling the temperature and duration of heat treatment helps to obtain the finished product of desired color.

On the defects of enamel coatings

2019 ◽  
pp. 145-150
Author(s):  
T. O. Soshina ◽  
V. R. Mukhamadyarovа
Keyword(s):  
Heat Treatment ◽  
Surface Tension ◽  
Electron Microscope ◽  
Enamel Coating ◽  
Surface Defects ◽  
Linear Expansion ◽  
Corrosion Properties ◽  
Treatment Conditions ◽  
Mechanical And Corrosion Properties ◽  
Coefficient Of Linear Expansion

The defects destroy the integrity of the enamel, and the paper examines the influence of the physical-mechanical and corrosion properties of frits and heat treatment on the defectiveness of the enamel coating. The surface defects were scanned by electron microscope. It has been established that the defectiveness of enamel coatings depends on the melting index, temperature coefficient of linear expansion, surface tension of the frits, and heat treatment conditions. When burning rate of the enamel coating decreases, the fine-meshed structure of the enamel changes, and the size of the defects decreases.

scholarly journals Heat Treatment Evaluation for the Camshafts Production of ADI Low Alloyed with Vanadium

Metals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1036
Author(s):  
Eduardo Colin García ◽  
Alejandro Cruz Ramírez ◽  
Guillermo Reyes Castellanos ◽  
José Federico Chávez Alcalá ◽  
Jaime Téllez Ramírez ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Tensile Strength ◽  
Ductile Iron ◽  
Volume Fraction ◽  
Energy Impact ◽  
Treatment Conditions ◽  
Mold Casting ◽  
Grade 3 ◽  
Good Agreement

Ductile iron camshafts low alloyed with 0.2 and 0.3 wt % vanadium were produced by one of the largest manufacturers of the ductile iron camshafts in México “ARBOMEX S.A de C.V” by a phenolic urethane no-bake sand mold casting method. During functioning, camshafts are subject to bending and torsional stresses, and the lobe surfaces are highly loaded. Thus, high toughness and wear resistance are essential for this component. In this work, two austempering ductile iron heat treatments were evaluated to increase the mechanical properties of tensile strength, hardness, and toughness of the ductile iron camshaft low alloyed with vanadium. The austempering process was held at 265 and 305 °C and austempering times of 30, 60, 90, and 120 min. The volume fraction of high-carbon austenite was determined for the heat treatment conditions by XRD measurements. The ausferritic matrix was determined in 90 min for both austempering temperatures, having a good agreement with the microstructural and hardness evolution as the austempering time increased. The mechanical properties of tensile strength, hardness, and toughness were evaluated from samples obtained from the camshaft and the standard Keel block. The highest mechanical properties were obtained for the austempering heat treatment of 265 °C for 90 min for the ADI containing 0.3 wt % V. The tensile and yield strength were 1200 and 1051 MPa, respectively, while the hardness and the energy impact values were of 47 HRC and 26 J; these values are in the range expected for an ADI grade 3.

Effect of copper incorporation on phase transformation behavior of electroless nickel–phosphorous coating and its effect on the tribological behavior

2020 ◽  
pp. 146442072098160
Author(s):  
Abhijit Biswas ◽  
Suman Kalyan Das ◽  
Prasanta Sahoo
Keyword(s):  
Heat Treatment ◽  
Phase Transformation ◽  
Tribological Behavior ◽  
Electroless Nickel ◽  
Two Phase ◽  
Microstructural Changes ◽  
Treatment Conditions ◽  
Heat Treated ◽  
Higher Temperature ◽  
Effect Of Copper

The microstructural changes of electroless Ni–P–Cu coating at various heat-treatment conditions are investigated to understand its implications on the tribological behavior of the coating. Coatings are heat-treated at temperatures ranging between 200°C and 800 °C and for 1–4 h duration. Ni–P–Cu coatings exhibit two-phase transformations in the temperature range of 350–450 °C and the resulting microstructural changes are found to significantly affect their thermal stability and tribological attributes. Hardness of the coating doubles when heat-treated at 452 °C, due to the formation of harder Ni3P phase and crystalline NiCu. Better friction and wear performance are also noted upon heat treatment of the coating at the phase transformation regime, particularly at 400 °C. Wear mechanism is characterized by a mixed adhesive cum abrasive wear phenomena. Heat treatment at higher temperature (600 °C and above) and longer duration (4 h) results in grain coarsening phenomenon, which negatively influences the hardness and tribological characteristics of the coating. Besides, diffusion of iron from the ferrous substrate as well as greater oxide formation are noticed when the coating is heat-treated at higher temperatures and for longer durations (4 h).

scholarly journals Recent Developments in Coatings for Orthopedic Metallic Implants

Coatings ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 791
Author(s):  
Muzamil Hussain ◽  
Syed Hasan Askari Rizvi ◽  
Naseem Abbas ◽  
Uzair Sajjad ◽  
Muhammad Rizwan Shad ◽  
...  
Keyword(s):  
Stress Shielding ◽  
Orthopedic Implant ◽  
Coating Materials ◽  
Implant Materials ◽  
Metallic Implants ◽  
Common Causes ◽  
Recent Developments ◽  
Orthopedic Applications ◽  
The Impact ◽  
Cocrmo Alloys

Titanium, stainless steel, and CoCrMo alloys are the most widely used biomaterials for orthopedic applications. The most common causes of orthopedic implant failure after implantation are infections, inflammatory response, least corrosion resistance, mismatch in elastic modulus, stress shielding, and excessive wear. To address the problems associated with implant materials, different modifications related to design, materials, and surface have been developed. Among the different methods, coating is an effective method to improve the performance of implant materials. In this article, a comprehensive review of recent studies has been carried out to summarize the impact of coating materials on metallic implants. The antibacterial characteristics, biodegradability, biocompatibility, corrosion behavior, and mechanical properties for performance evaluation are briefly summarized. Different effective coating techniques, coating materials, and additives have been summarized. The results are useful to produce the coating with optimized properties.

Sign in / Sign up

Export Citation Format

Share Document