scholarly journals Additively Manufactured NiTi and NiTiHf Alloys: Estimating Service Life in High-Temperature Oxidation

Materials ◽  
2020 ◽  
Vol 13 (9) ◽  
pp. 2104 ◽  
Author(s):  
Hediyeh Dabbaghi ◽  
Keyvan Safaei ◽  
Mohammadreza Nematollahi ◽  
Parisa Bayati ◽  
Mohammad Elahinia
Keyword(s):  
High Temperature ◽  
Oxidation Rate ◽  
High Temperature Oxidation ◽  
Oxidation Behavior ◽  
Early Stage ◽  
Niti Alloy ◽  
Temperature Oxidation ◽  
X Ray ◽  
Rate Law ◽  
Parabolic Rate

In this study, the effect of the addition of Hf on the oxidation behavior of NiTi alloy, which was processed using additive manufacturing and casting, is studied. Thermogravimetric analyses (TGA) were performed at the temperature of 500, 800, and 900 °C to assess the isothermal and dynamic oxidation behavior of the Ni50.4Ti29.6Hf20 at.% alloys for 75 h in dry air. After oxidation, X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray spectroscopy were used to analyze the oxide scale formed on the surface of the samples during the high-temperature oxidation. Two stages of oxidation were observed for the NiTiHf samples, an increasing oxidation rate during the early stage of oxidation followed by a lower oxidation rate after approximately 10 h. The isothermal oxidation curves were well matched with a logarithmic rate law in the initial stage and then by parabolic rate law for the next stage. The formation of multi-layered oxide was observed for NiTiHf, which consists of Ti oxide, Hf oxide, and NiTiO3. For the binary alloys, results show that by increasing the temperature, the oxidation rate increased significantly and fitted with parabolic rate law. Activation energy of 175.25 kJ/mol for additively manufactured (AM) NiTi and 60.634 kJ/mol for AM NiTiHf was obtained.

Effect of Yttrium Addition on High Temperature Oxidation Resistance of Co-10Cr-5Al Alloys

2011 ◽  
Vol 391-392 ◽  
pp. 606-610 ◽  
Author(s):  
Huai Shu Zhang ◽  
Hong Hua Zhang ◽  
Jun Huai Xiang ◽  
Shan Wang ◽  
Di Wu
Keyword(s):  
High Temperature ◽  
Oxidation Resistance ◽  
Oxidation Rate ◽  
High Temperature Oxidation ◽  
Oxidation Behavior ◽  
Temperature Oxidation ◽  
Linear Rate ◽  
Rate Law ◽  
Yttrium Addition ◽  
Parabolic Rate

The oxidation behavior of Co-10Cr-5Al-0.3Y alloy in 1 atm of pure O2 at 700°C was investigated. The addition of 0.3 at.%Y significantly increased the oxidation rate of the alloy and changed the oxidation behavior from the approximate parabolic rate law to linear rate law. The scale grown on the surface at 700°C was porous with many small voids and cracks, and was composed of an outer CoO layer and an inner complex layer rich in Al2O3 and Cr2O3 which were intermingled with yttric oxide and spinel Co(Cr, Al)2O4.

High Temperature Oxidation Behavior of Arc-sprayed FeCrBAlMo Coating

2016 ◽  
Vol 19 (1) ◽  
Author(s):  
Xin Zhang ◽  
Zehua Wang ◽  
Jinran Lin
Keyword(s):  
High Temperature ◽  
High Temperature Oxidation ◽  
Oxidation Behavior ◽  
Steel Substrate ◽  
Arc Spraying ◽  
X Ray Diffraction ◽  
Temperature Oxidation ◽  
X Ray ◽  
High Velocity Arc Spraying ◽  
High Temperature Oxidation Behavior

AbstractFeCrBAlMo coating was deposited on an AISI 20 steel substrate by high velocity arc spraying (HVAS). Compared with FeCrBSiMo coating and pristine AISI 20 steel, the microstructure and high temperature oxidation behavior of FeCrBAlMo coating were investigated by optical microscopy, scanning electron microscopy, energy-dispersive spectroscopy and X-ray diffraction. Meanwhile, the bonding strength of the coatings was also measured. The results indicated that both coatings were composed of α(Fe,Cr) and Fe

scholarly journals High Temperature Oxidation Behaviors of CrNx and Cr-Si-N Thin Films at 1000 °C

Coatings ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 540 ◽  
Author(s):  
Bih-Show Lou ◽  
Yue-Chyuan Chang ◽  
Jyh-Wei Lee
Keyword(s):  
Thin Films ◽  
High Temperature ◽  
Oxide Layer ◽  
Oxidation Resistance ◽  
High Temperature Oxidation ◽  
Temperature Oxidation ◽  
X Ray ◽  
Oxidation Test ◽  
Parabolic Rate ◽  
Oxidation Behaviors

The high temperature oxidation performance of nitride thin films has become an important issue when they are used as protective coatings on dry cutting tools or on die casting molds. In this study, the high temperature oxidation behaviors of CrNx and Cr-Si-N thin films were investigated at 1000 °C for 6 h in ambient air. The CrNx and Cr-Si-N thin films were prepared by a bipolar asymmetric pulsed direct-current (DC) magnetron sputtering system. Cr-Si-N films with silicon content ranging from 3.9 to 12.2 at.% were deposited by adjusting the Si target power. A thermogravimeter was adopted to study the oxidation kinetics of thin films. The weight gains were measured to calculate the parabolic rate constants of thin films. X-ray diffraction, X-ray mapping, and Auger electron spectroscopy were employed to study the microstructure and elemental redistributions of oxidized thin films. The as-deposited CrNx and Cr-Si-N thin films consisted of CrN and Cr2N mixed phases. The faceted Cr2O3 surface oxides, porous inner oxide layer, and oxygen-containing CrSi2 phases were found for the CrN film after oxidation test. On the other hand, the Cr-Si-N film containing 12.2 at.% Si showed a dense surface oxide layer and a thick and compact nitride layer, which indicates its best oxidation resistance. The high temperature oxidation resistance of Cr-Si-N thin films was improved by increasing Si content, due to the amorphous matrix contained nanocomposite microstructure and the formation of amorphous silicon oxide to retard the diffusion paths of oxygen, chromium, silicon, and nitrogen. The lowest parabolic rate constant of 1.48 × 10–2 mg2/cm4/h was obtained for the 12.2 at.% Si contained Cr-Si-N thin films, which provided the best oxidation resistance at 1000 °C for 6 h in this work. It should be noted that the residual tensile stress of thin film had a detrimental effect on the adhesion property during the oxidation test.

High Temperature Oxidation Behavior of ZrB2-SiC-Graphite Composite Heated by High Electric Current

2010 ◽  
Vol 105-106 ◽  
pp. 162-164
Author(s):  
Hong Bo Chen ◽  
Song He Meng
Keyword(s):  
High Temperature ◽  
Electric Current ◽  
High Temperature Oxidation ◽  
Oxidation Behavior ◽  
X Ray Diffraction ◽  
Temperature Oxidation ◽  
Graphite Composite ◽  
X Ray ◽  
High Temperature Oxidation Behavior ◽  
Oxidation Testing

High temperature oxidation testing was carried out on hot-pressed ZrB2-SiC-graphite composite by using high electric current heating. The composites oxidation behavior was investigated, the temperature of oxidized specimens was above 2000°C. The results found that the UHTC composite was ruptured at oxidized temperature 2055°C. The microstructure of surface and cross-section of posttest samples were investigated by scanning electron microscopy along with energy and X-ray diffraction. The failure mechanism of rupture was also discussed.

Thermogravimetric Investigations of Novel γ–γ′ Co-Al-W and Co-Al-Mo-Nb Cobalt-Based Superalloys

2019 ◽  
Vol 141 (4) ◽  
Author(s):  
Grzegorz Moskal ◽  
Damian Migas ◽  
Dawid Niemiec ◽  
Agnieszka Tomaszewska
Keyword(s):  
High Temperature ◽  
High Temperature Oxidation ◽  
Oxidation Behavior ◽  
Elevated Temperatures ◽  
X Ray Diffraction ◽  
Temperature Oxidation ◽  
Turbine Engine ◽  
X Ray ◽  
Thermogravimetric Studies ◽  
Thermogravimetric Investigations

Cobalt-based γ–γ′ superalloys are novel heat-resistant materials suitable for high-temperature applications, such as components of the turbine engine. These alloys exhibit favorable strength and corrosion resistance at high temperatures owing to the γ–γ′ microstructure, analogous to that of Ni-based superalloys. The aim of this paper is to evaluate the oxidation behavior of basic Co-9Al-9W (at%) and new tungsten-free Co-10Al-5Mo-2Nb (at%) alloys at elevated temperatures. The investigation is concerned with thermogravimetric studies in the temperature range of 40–1200 °C. The oxidized surfaces after high temperature oxidation have been characterized using optical microscopy (OM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction analysis (XRD).

Oxidation Resistance of Co-10Cr-5Si-0.3Y Alloys at 800°C

2011 ◽  
Vol 391-392 ◽  
pp. 615-619
Author(s):  
Peng Li ◽  
Jun Huai Xiang ◽  
Hong Hua Zhang ◽  
Yang Zhang ◽  
Jian Rong Zhu
Keyword(s):  
High Temperature ◽  
Oxidation Resistance ◽  
Internal Oxidation ◽  
Outer Layer ◽  
Oxidation Rate ◽  
High Temperature Oxidation ◽  
Temperature Oxidation ◽  
Linear Rate ◽  
Rate Law ◽  
Inner Region

The effect of the addition of 0.3 at.% Y on high temperature oxidation resistance of ternary Co-10Cr-5Si alloy in 0.1MPa O2 at 800°C was investigated. The addition of 0.3 at.% Y greatly increased the oxidation rate of the alloy and changed the approximate parabolic rate law into linear rate law. The scale formed on Co-10Cr-5Si-0.3Y alloy was double-layered, with formation of an outer layer of CoO and an inner region containing a mixture of CoO, Cr2O3, SiO2 and a trace of yttric oxide, coupled to the internal oxidation region of Si.

High-Temperature Oxidation Behavior of Cu-20Ni-75Co Alloy

2013 ◽  
Vol 750-752 ◽  
pp. 659-662
Author(s):  
Zhong Qiu Cao ◽  
Feng Chun Li ◽  
Ying Shen
Keyword(s):  
High Temperature Oxidation ◽  
Oxidation Behavior ◽  
External Layer ◽  
Temperature Oxidation ◽  
Rate Law ◽  
Oxidation Rates ◽  
Present Alloy ◽  
Alloy Increase ◽  
Parabolic Rate ◽  
High Temperature Oxidation Behavior

The oxidation of a ternary Cu-Ni-Co alloy containing about 20 at.% Ni and 75 at.% Co, balance Cu (Cu-20Ni-75Co), was studied at 600-800°C in 0.1MPa pure O2. The kinetic curves for the present alloy are irregular and deviate from the parabolic rate law and are composed of three quasi-parabolic stages. The oxidation rates decrease continuously with time more rapidly than required by the parabolic rate law. These indicate that the scales become more protective with the increment of time. The oxidation rates of the present alloy increase with the increment of temperature. Cu-20Ni-75Co alloy formed a dark external layer composed of Co3O4 followed by a slightly lighter internal layer of CoO. Obviously, adding 20 at% Ni to Cu-75Co alloy is able to decrease the critical Co content required to form the most stable oxide and finish a transformation from the mix internal oxidation to the formation of the exclusive external scales of Co oxides.

scholarly journals High-Temperature Oxidation Kinetics of Additively Manufactured NiTiHf

2020 ◽  
Author(s):  
Hediyeh Dabbaghi ◽  
Mohammadreza Nematollahi ◽  
Keyvan Safaei Baghbaderani ◽  
Parisa Bayatimalayeri ◽  
Mohammad Elahinia
Keyword(s):  
High Temperature ◽  
Shape Memory Alloys ◽  
Shape Memory ◽  
Oxidation Kinetics ◽  
Oxidation Rate ◽  
Oxidation Behavior ◽  
Transformation Temperatures ◽  
X Ray ◽  
Rate Law ◽  
Kinetics Of

Abstract NiTi-based high-temperature shape memory alloys (HTSMAs) such as NiTiHf have been utilized in a broad range of applications due to their high strength and work output, as well as, their ability to increase the transformation temperatures (TTs). Recently, additive manufacturing techniques (AM) have been widely used to fabricate complex shape memory alloy components without any major modifications or tooling and has paved the way to tailor the manufacturing and fabrications of microstructure and critical properties of their final parts. NiTi alloys properties such as transformation temperatures can be significantly altered due to oxidation, which can occur during the manufacturing process or post-processing. In this work, the oxidation behavior of Ni-rich NiTi20Hf shape memory alloys, which was fabricated by the selective laser melting (SLM) method, is evaluated. Thermogravimetric analysis (TGA) is used to assess the kinetic behavior of the oxidation at different temperature ranges of 500, 700, and 900 °C for 20 hours in the air. After oxidation, to evaluate the microstructure and chemical composition X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS) was conducted. The isothermal oxidation kinetics of conventional NiTi20Hf alloys were studied, and the results were compared to AM samples. Results show a two-stage oxidation rate at which oxidation increased with the high rate at the initial stage. As the oxidation time increased, the oxidation rate gradually decreased. The oxidation behavior of NiTiHf alloys initially obeyed logarithmic rate law and then followed by parabolic rate law. SEM results showed the formation of a multi-layered oxide scale, including TiO2, NiTiO3, and Hf oxide.

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