Improved in vitro bioactivity and electrochemical behavior of hydroxyapatite-coated NiTi shape memory alloy

Sattar, Tahir; Manzoor, Tareq; Khalid, Fazal Ahmad; Akmal, Muhammad; Saeed, Ghuzanfar

doi:10.1007/s10853-018-03304-8

Cited by 16 publications

(7 citation statements)

References 23 publications

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“…Since metals have a crystalline structure, so the pattern consists of peaks, where the angle of detection, wideness, and intensity of the peaks give valuable information about the crystal structure of the material. The XRD is not for a single atom crystal structure, but it can be used for complicated molecules and to find different compounds [71]. Some phases after phase transformation will not completely transformed, such as austenite ↔ martensite phase, and the DSC results cannot give any information about the residual phases and other precipitations that can influence the physical properties of a SMA.…”

Section: Tg/dtamentioning

confidence: 99%

The Effect of Different Parameters on Shape Memory Alloys

Qader

Kök

Dağdelen

et al. 2020

Sakarya University Journal of Science

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Shape memory alloys' characteristics are different from ordinary materials because they can memorize their predetermined shape, thus they are excellent candidates for different applications. In this review article, the most interesting parameters that researchers are using in their investigation have been highlighted. Also, the popular techniques used for the characterization of shape memory alloys have been described. The diagrams and sketches can show a clear view of metallurgies and related research areas.

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Section: Tg/dtamentioning

confidence: 99%

The Effect of Different Parameters on Shape Memory Alloys

Qader

Kök

Dağdelen

et al. 2020

Sakarya University Journal of Science

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“…In [ 27 ], a calcium phosphate coating on nickelide titanium alloy improved its biocompatibility and mechanical properties, making it a promising candidate for biomedical applications. Calcium-phosphate-coated NiTi has improved in vitro bioactivity and electrochemical behavior and is more effective in suppressing nickel ion leaching than uncoated and thermally oxidized NiTi [ 28 , 29 ]. Hydroxyapatite crystals formed on the coated NiTi surface after immersion in artificial body fluid for 7 days, confirming its surface bioactivity [ 30 ].…”

Section: Introductionmentioning

confidence: 99%

Properties of Coatings Based on Calcium Phosphate and Their Effect on Cytocompatibility and Bioactivity of Titanium Nickelide

et al. 2023

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Coatings based on calcium phosphate with thicknesses of 0.5 and 2 μm were obtained by high-frequency magnetron sputtering on NiTi substrates in an argon atmosphere. The coating was characterized using X-ray diffraction, scanning electron microscopy, atomic force microscopy, and in vitro cytocompatibility and bioactivity studies. A biphasic coating of tricalcium phosphate (Ca3(PO4)2) and hydroxyapatite (Ca10(PO4)6(OH)2) with a 100% degree of crystallinity was formed on the surface. The layer enriched in calcium, phosphorus, and oxygen was observed using scanning electron microscopy and energy-dispersive X-ray spectroscopy. Scanning electron microscopy showed that the surface structure is homogeneous without visible defects. The 2 µm thick coating obtained by sputtering with a deposition time of 4 h and a deposition rate of 0.43 µm/h is uniform, contains the highest amount of the calcium phosphate phase, and is most suitable for the faster growth of cells and accelerated formation of apatite layers. Samples with calcium phosphate coatings do not cause hemolysis and have a low cytotoxicity index. The results of immersion in a solution simulating body fluid show that NiTi with the biphasic coating promotes apatite growth, which is beneficial for biological activity.

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“…For near equiatomic NiTi (50 at% Ni) alloys, the reversible martensitic phase transformation can be accomplished by the one-step phase transformation, i.e., the phase transformation between the high-temperature stable austenite (cubic B2-type crystal structure) and the low-temperature stable martensite (monoclinic B19-type crystal structure) [1,3,4]. Owing to their remarkable properties, NiTi SMAs are widely used in fields, such as actuators [5], dampers [6], sensors [7] and medical devices [8,9].…”

Section: Introductionmentioning

confidence: 99%

Controlling microstructure evolution and phase transformation behavior in additive manufacturing of nitinol shape memory alloys by tuning hatch distance

et al. 2022

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Laser powder bed fusion (L-PBF), categorized as additive manufacturing technique, has a capability to fabricate NiTi (Nitinol) shape memory alloys with tailorable functional properties and complex geometries. An important processing parameter, hatch distance (h), is often related to macroscale structural defects; however, its role on controlling the microstructure and functional properties is usually underestimated in L-PBF of NiTi. In this work, equiatomic NiTi (50.0 at% Ni) parts were fabricated with various hatch distances to tailor the microstructure and their shape memory characteristics. Contrary to what is observed in Ni-rich NiTi alloys, in this work, we demonstrate that phase transformation temperatures of L-PBF equiatomic NiTi do not decrease proportionally with hatch distance but rather relate to a critical hatch distance value. This critical value (120 μm) is derived from the synergistic effect of thermal stress and in situ reheating. Below this value, epitaxial grain growth and in situ recrystallization are enhanced, while above, irregular grains are formed and dislocations induced by thermal stresses decrease. However, the critical value found herein is characterized by high dislocation density and fine grain size, resulting in a superior thermal cyclic stability. The proposed finite element model is proven to be an effective tool to understand and predict the effect of hatch distance on grain morphology and dislocation density evolutions in L-PBF NiTi SMAs. In the present study, we provide a comprehensive understanding for in situ controlling L-PBF NiTi microstructure and functional characteristics, which contributes to designing 4-dimensional shape memory alloys.

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Improved in vitro bioactivity and electrochemical behavior of hydroxyapatite-coated NiTi shape memory alloy

Cited by 16 publications

References 23 publications

The Effect of Different Parameters on Shape Memory Alloys

The Effect of Different Parameters on Shape Memory Alloys

Properties of Coatings Based on Calcium Phosphate and Their Effect on Cytocompatibility and Bioactivity of Titanium Nickelide

Controlling microstructure evolution and phase transformation behavior in additive manufacturing of nitinol shape memory alloys by tuning hatch distance

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