Oxidation-resistant coating for gamma titanium aluminides by pack cementation

Mikami, Hiroshi; Tsuda, Hiroshi; Kawakami, Tadashi; Nakamatsu, Sandra; Matsui, Toshiyuki; Morii, K.

doi:10.1016/s1359-6462(99)00182-7

Cited by 33 publications

(7 citation statements)

References 25 publications

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“…The main purpose of this study was to investigate the factors determining the thickness growth of coats during PC treatment. The results obtained here, however, showed a different growth process than that expressing a parabolic saturation pattern, 11) instead exhibiting temperature dependence only at two values, as mentioned above. In the following discussion, therefore, we consider only the mechanism exhibiting the two-value temperature dependence.…”

Section: Discussioncontrasting

confidence: 47%

“…10) A successful improvement has been reported recently on the alloy's heat resistance at 1273 K, in which a PC coat is applied using an L1 2 -type compound (AlCr) 3 Ti. 11) In dealing with coating by compounds, however, the relevant mechanisms have yet to be clarified. These mechanisms, which include factors in the composition and thickness control of the coating, must be studied.…”

Section: Introductionmentioning

confidence: 99%

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Surface Modification of Gamma-Titanium Aluminides with L1<SUB>2</SUB>-Type Tri-Aluminides by Pack Cementation

et al. 2005

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The surface of an L1 0 -type TiAl base alloy has been modified by coating it with an L1 2 -phase (AlMn) 3 Ti(V) using a pack-cementation method in a temperature range of 1273-1473 K and with a treatment time of 18-72 ks. The structural morphology and composition distribution in the coat and substrate were analyzed by EPMA and XRD to examine the factors that control the thickness of the coat. Two-phase equilibrium was confirmed between the L1 0 -phase substrate and the L1 2 -phase coat at each temperature tested. Aluminum particulates, 1-2 mm in diameter, were observed inside the coat and were confirmed to be related to the experimental condition and to the increase in coat thickness. The coat is 35 mm thick at temperature range of 1373-1473 K, while at the temperature range of 1273-1323 K the thickness is 11-12 mm. The temperature dependence of coating layer is different from that was reported previously. The results are then discussed from facts basically revealed in this experiment and/or based on information about the phase equilibrium between L1 0 and L1 2 .

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Section: Discussioncontrasting

confidence: 47%

Section: Introductionmentioning

confidence: 99%

Surface Modification of Gamma-Titanium Aluminides with L1<SUB>2</SUB>-Type Tri-Aluminides by Pack Cementation

et al. 2005

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“…[1][2][3][4] The previous two problems can be solved by the application of oxidation-resistant coatings on the surface of the titanium alloy. [5][6][7][8][9] These coated titanium alloys, however, can not yet work above 600°C for a reasonably long time because of the loss of plasticity due to the precipitation of undesired thermal products such as Ti 3 X or silicides. [1][2][3] Also, the high-temperature fatigue failure is still limiting the further wide application of the titanium alloy.…”

Section: Introductionmentioning

confidence: 99%

Thermal failure of thermal barrier coating with thermal sprayed bond coating on titanium alloy

Zhou

et al. 2008

J Coat Technol Res

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A thermal spray technology high-velocity oxygen fuel (HVOF) was used to deposit NiCoCrAlY as a bond coating between the titanium alloy substrate and top 8 wt% yttria-stabilized zirconia thermal-barrier coating (TBC) deposited by electron beam-physical vapor deposition (EB-PVD). The thermal cycling and isothermal exposure tests were conducted to evaluate the durability of the TBC. Investigations using OM, SEM, EPMA, and XRD revealed that the thermalsprayed BC makes the TBC more durable in isothermal exposure tests but more short-lived in thermal cycling tests, in comparison to our previous study in which the BC was prepared by EB-PVD. This is because the thermal-sprayed imperfections, such as microcracks and voids, elevate the diffusion resistance and degrade the mechanical properties of the BC, simultaneously. To current TBC systems in which the BC is deposited by HVOF, thermal failure behaviors-such as the formation of the Ti/Al mixture oxides at some individual places in the BC, and the Ti 2 Ni gaps formed around the BC/substrate interface-were also discussed.

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“…1 One promising way to overcome the above drawbacks of Ti-based alloys would be to deposit stable coatings to protect the substrate from long-term oxidation and oxygen embrittlement. There is an ongoing interest in the development of oxygen-barrier coatings, such as ceramic oxides (Al 2 O 3 2,3 , SiO 2 4 ), MCrAlY 5,6 , aluminide 7,8 , and TiAlCr-based 9-14 coatings. In recent years, however, a promising enamel coating was developed to protect Ti-based alloys from oxidation and corrosion due to its high thermochemical stability and matched thermal expansion coefficient (8.8-11 · 10 -6 /°C) with the substrate.…”

Section: Introductionmentioning

confidence: 99%

Effect of vitreous enamel coating on the oxidation behavior of Ti6Al4V and TiAl alloys at high temperatures

et al. 2007

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Vitreous enamel coating is a promising candidate as a high temperature protective coating for titanium (Ti)-based alloys due to its high thermochemical stability, compatibility, and matching thermal expansion coefficient to the substrates. Vitreous enamel coating is economically attractive because of its low cost and easy handling. The oxidation behavior of Ti6Al4V (at 700°C) and Ti-48Al (at 800-900°C), with and without the vitreous enamel coating exposed to air, are investigated in this article. The results show that the vitreous enamel coating could markedly protect the substrate (Ti6Al4V and Ti48Al) from oxidation at elevated temperatures. In comparison, the TiAlCr coating might not provide long-term protection for the Ti6Al4V alloys due to the heavy interfacial interdiffusion at high temperatures, although a protective Al 2 O 3 scale could form at the initial oxidation stage. The vitreous enamel coating remains intact, uniform, compact, and adhesive to the substrate, however, with undetectable interfacial reaction after oxidation. It is also worth noting that some new phases form in the coating during oxidation at 900°C, although the protectiveness of the coating seems to be unaffected.

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Oxidation-resistant coating for gamma titanium aluminides by pack cementation

Cited by 33 publications

References 25 publications

Surface Modification of Gamma-Titanium Aluminides with L1<SUB>2</SUB>-Type Tri-Aluminides by Pack Cementation

Surface Modification of Gamma-Titanium Aluminides with L1<SUB>2</SUB>-Type Tri-Aluminides by Pack Cementation

Thermal failure of thermal barrier coating with thermal sprayed bond coating on titanium alloy

Effect of vitreous enamel coating on the oxidation behavior of Ti6Al4V and TiAl alloys at high temperatures

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