The Effect of Inclusions on Fatigue Properties for Nitinol

Urbano, Marco; Coda, Alberto; Beretta, S.; Cadelli, Andrea; Sczerzenie, Frank

doi:10.1520/stp155920120189

Cited by 10 publications

(9 citation statements)

References 14 publications

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“…Fatigue strength of metallic materials is deteriorated by a variety of small defects, for example, non‐metallic inclusions, cavities, microstructural irregularities and cracks . Thus, the effect of small defects has been a major concern for fatigue researchers for many years.…”

Section: Introductionmentioning

confidence: 99%

Effect of small defect orientation on fatigue limit of carbon steels

Lorenzino

Okazaki

Matsunaga

et al. 2015

Fatigue Fract Eng Mat Struct

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In order to clarify the effect of defect orientation on the fatigue limit of two types of steels, JIS‐S15C and JIS‐S45C, a small semi‐circular slit was introduced onto the surface of a round specimen. The slit was tilted at 0 °, 30 ° or 60 ° with respect to the plane normal to the loading axis, but all of them had the same defect size, area = 188 µm, where the area denotes the area of the domain defined by projecting the defect on a plane normal to the loading axis. In all the combinations of the materials and tilt angles, a non‐propagating crack was found at or just below the fatigue limit, that is, the fatigue limit was determined by the non‐propagation condition of a crack initiated from the defect. In both steels, the fatigue limit was found to be nearly independent of the tilt angle for the same value of projected size area, which was in good agreement with the prediction by the area parameter model. In this paper, a mechanistic explanation for the insensitivity of the fatigue limit to the tilt angle is proposed.

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Section: Introductionmentioning

confidence: 99%

Effect of small defect orientation on fatigue limit of carbon steels

Lorenzino

Okazaki

Matsunaga

et al. 2015

Fatigue Fract Eng Mat Struct

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“…Also, regarding oxide-type inclusions (i.e., Ti 2 NiO x ) Liang and Huang [4] have found that their presence is the main reason for pitting. Coda et al [5] characterized the main types of inclusions of commercial Nitinol produced by VIM and vacuum arc melting (VAR) routes; by means of extreme value statistics, Urbano et al [6] showed that the maximum inclusion dimension in the highly strained volume of a fatigue test contributes to a decrease in the fatigue performance of 0.3-mm-diameter superelastic wires. Morgan et al [7] reported about extra low inclusions content (ELI) alloys appeared to have improved fatigue performances.…”

Section: Introductionmentioning

confidence: 99%

Plasma Arc Melting (PAM) and Corrosion Resistance of Pure NiTi Shape Memory Alloys

Tuissi

Rondelli

Bassani

2015

Shap. Mem. Superelasticity

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Plasma arc melting (PAM) as a suitable noncontaminating melting route for manufacturing high-quality NiTi alloy was successfully examined. The corrosion resistance of PAM Nitinol was evaluated by both potentiodynamic and potentiostatic tests and compared with lower purity NiTi produced by vacuum induction melting (VIM). For the electro-polished surfaces, excellent corrosion resistance of NiTi comparable with the Ti alloys was found with no pitting up to 800 mV versus saturated calomel electrode in simulated body fluid at 37°C. Potentiostatic results of PAM Nitinol indicate slightly better corrosion resistance than the lower quality VIM alloy.

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“…The electro-arc melting technology of nitinol alloys seems to be useless, while their manufacturing by the vacuum arc remelting (VAR) [221,225] of high purity [225], with a smaller (usually 5-10 times smaller) proportion of non-metallic inclusions than in the case of standard melt and fatigue strength several times higher [225]. The most advantageous is the manufacturing of nitinol by the vacuum induction melting (VIM) method, which ensures the lowest possible share of non-metallic inclusions [225] and increased fatigue strength [222,223].…”

Section: Methods and Tools Of Root Canal Preparation In Endodontic Treatmentmentioning

confidence: 99%

Is Gutta-Percha Still the “Gold Standard” among Filling Materials in Endodontic Treatment?

Dobrzańska¹,

Dobrzański²,

Dobrzański³

et al. 2021

Processes

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The paper is an extensive monographic review of the literature, and also uses the results of the authors’ own experimental research illustrating the noticed developmental tendencies of the filling material based on gutta-percha. The whole body of literature proves the correctness of the research thesis that this material is the best currently that can be used in endodontics. Caries is one of the most common global infectious diseases. Since the dawn of humankind, the consequence of the disease has been the loss of dentition over time through dental extractions. Both tooth caries and tooth loss cause numerous complications and systemic diseases, which have a serious impact on insurance systems and on the well-being, quality, and length of human life. Endodontic treatment, which has been developing since 1836, is an alternative to tooth extraction. Based on an extensive literature review, the methodology of qualifying patients for endodontic treatment was analyzed. The importance of selecting filling material and techniques for the development and obturation of the root canal during endodontic treatment was described. Particular attention was paid to the materials science aspects and the sequence of phase transformations and precipitation processes, as well as the need to ensure the stoichiometric chemical composition of Ni–Ti alloys, and the vacuum metallurgical processes and material processing technologies for the effects of shape memory and superelasticity, which determine the suitability of tools made of this alloy for endodontic purposes. The phenomena accompanying the sterilization of such tools, limiting the relatively small number of times of their use, play an important role. The methods of root canal preparation and obturation methods through cold side condensation and thermoplastic methods, including the most modern of them, the thermo-hydraulic condensation (THC) technique, were analyzed. An important element of the research hypothesis was to prove the assumption that to optimize the technology of development and obturation of root canals, tests of filling effectiveness are identified by the density and size of the gaps between the root canal wall, and the filling methods used and devices appropriate for material research, using mainly microscopy such as light stereoscopic (LSM) and scanning electron (SEM). The most beneficial preparations were obtained by making a longitudinal breakthrough of 48 natural human teeth, extracted for medical reasons, different from caries, with compliance with all ethical principles in this field. The teeth were prepared using various methods and filled with multiple obturation techniques, using a virtual selection of experimental variants. The breakthroughs were made in liquid nitrogen after a one-sided incision with a narrow gap created by a diamond disc using a materialographic cutter. The best effectiveness of the root canal filling was ensured by the technology of preparing the root canals with K3 rotary nitinol tools and filling the teeth with the THC thermoplastic method using the System B and Obtura III devices with studs and pellets of filling material based on gutta-percha after covering the root canal walls with a thin layer of AH Plus sealant. In this way, the research thesis was confirmed.

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The Effect of Inclusions on Fatigue Properties for Nitinol

Cited by 10 publications

References 14 publications

Effect of small defect orientation on fatigue limit of carbon steels

Effect of small defect orientation on fatigue limit of carbon steels

Plasma Arc Melting (PAM) and Corrosion Resistance of Pure NiTi Shape Memory Alloys

Is Gutta-Percha Still the “Gold Standard” among Filling Materials in Endodontic Treatment?

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