Repair of Ni-based single-crystal superalloys using vacuum plasma spray

Kalfhaus, Tobias; Schneider, Mike; Ruttert, Benjamin; Sebold, Doris; Hammerschmidt, Thomas; Frenzel, Jan; Drautz, Ralf; Theisen, W.; Eggeler, Gunther; Guillon, Olivier; Vaßen, Robert

doi:10.1016/j.matdes.2019.107656

Cited by 16 publications

(16 citation statements)

References 36 publications

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“…Following, two precipitation heat treatments were undertaken, one by HIP and one in a furnace under a protective argon atmosphere. More experimental details can be found in Kalfhaus et al [56] As the feedstock kinetic energy plays a key role in CGS, in-flight particle velocity measurements are appropriate to investigate and monitor the process. Yin et al [69] gave a Figure 1.…”

Section: Methodsmentioning

confidence: 99%

“…To reduce the solidification rate of the splats, a heated sample holder was used during the coating process of a polished single-crystalline substrate at a temperature of 1000 C. [56] The microstructure of the interface was analyzed by SEM and EBSD. Figure 9a represents an image of the forescatter diodes which reveals the low porosity level of the coating.…”

Section: Polycrystalline Repairmentioning

confidence: 99%

“…In further microstructure investigations, oxides were identified as Al 2 O 3 and the impurity phase on the grain boundaries as a μ-type topologically close-packed phase. [56] The measured oxide content can be related to the grain size by an oxygen analysis of the heat-treated samples. The samples with spray parameters that lead to a thick bead have a lower oxide content.…”

Section: Polycrystalline Repairmentioning

confidence: 99%

“…Samples prepared with a thick bead grew during the heat treatment to a grain size larger than 10 μm. [56] This repair process can be used to produce polycrystalline repair layers on damaged parts with small structural deviations of the original component dimensions and a low mechanical load regarding the layer thickness. In addition, the formation of interdiffusion phases due to the use of the same alloys is excluded.…”

Section: Polycrystalline Repairmentioning

confidence: 99%

“…Unfortunately, the properties of Ti-48Al-2Cr-2Nb, namely, the 1) low density, 2) high brittle-to-ductile transition temperature (750 C), [46] and 3) high strain rate sensitivity [47] and yield stress anomaly, [48] impede the deposition of coatings by CGS, as reported by Bakan et al [49] With the CGS process, only polycrystalline components can be restored, but another challenge is the repair of single-crystalline turbine blades. As an alternative to laser cladding, [50][51][52][53][54][55] Kalfhaus et al [56] used vacuum plasma spraying (VPS) and demonstrated its potential capability to repair single-crystalline turbine blades.…”

Section: Introductionmentioning

confidence: 99%

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Thermal Spray Processes for the Repair of Gas Turbine Components

et al. 2020

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Gas turbine components are often operated in harsh conditions, which can lead to severe damage. As it is highly desirable from both an economical and an ecological point of view to restore these worn areas instead of manufacturing new components, repair technologies are of huge interest for companies supplying maintenance and overhaul of gas turbines. In this article, two thermal techniques are described that can be used for this application: cold gas spraying (CGS) and vacuum plasma spraying (VPS). The CGS process allows the deposition of metallic coatings with excellent mechanical properties; several examples including γ-TiAl, Inconel (IN) 718, and IN 738 are given. Essential for the deposition of high-performance coatings in CGS is to exceed the so-called critical velocity. This is discussed also with experimental findings. As a final topic, experiments that use VPS for the repair of single-crystal alloys are described.

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Section: Methodsmentioning

confidence: 99%

Section: Polycrystalline Repairmentioning

confidence: 99%

Section: Polycrystalline Repairmentioning

confidence: 99%

Section: Polycrystalline Repairmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Thermal Spray Processes for the Repair of Gas Turbine Components

et al. 2020

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In Situ Generation of TiCN Ni‐Based Coatings by Laser Cladding and Study of Their Structure and Properties

Li,

Yao

2024

Adv Eng Mater

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The influence of the ratio of TiN powder, graphite powder, and Ni60 powder on the phase composition, microstructure, microhardness, and wear properties of the TiCN Ni‐based coating on H13 steel was investigated. The findings indicate that varying proportions of TiN powder, C powder, and Ni60 powder have a minimal impact on the coating’s phase composition. The diffraction peak intensity of TiC0.3N0.7 increases with the addition of (C+TiN) in the blended powder, while the crystallinity of TiC0.3N0.7 in the Ni‐based coating with a 30% (C+TiN) mass fraction decreases. The grain structure of the 20% Ni‐based coating is fine and uniform, while the microstructure of the 30% Ni‐based coating is characterized by a large polymerization phase containing Ti elements, with the TiCN‐reinforced phase exhibiting irregular grain morphology. The microhardness HV0.5 of the coating with a 20% (C+TiN) mass fraction ranges from 725 to 772, with an average hardness of 747.8 HV0.5, which is 3.4 times the hardness of the substrate material and 1.3 times the hardness of the Ni‐based coating. As the mass fraction of (C+TiN) in the hybrid powder increases, the friction loss mass of the coating tends to decrease and then increase. The average wear of the Ni‐based coating with a 20% (C+TiN) mass fraction is approximately 22.4% of that of the substrate and 50% of that of the Ni‐based coating, demonstrating excellent wear resistance. The wear mechanism is primarily characterized by brittle spalling and abrasive wear.This article is protected by copyright. All rights reserved.

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Quantifying Equiaxed vs Epitaxial Solidification in Laser Melting of CMSX-4 Single Crystal Superalloy

Jiang

Ren

Aroh

et al. 2022

Metall Mater Trans A

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The competition between epitaxial vs. equiaxed solidification has been investigated in CMSX-4 single crystal superalloy during laser melting as practiced in additive manufacturing. Single-track laser scans were performed on a powder-free surface of directionally solidified CMSX-4 alloy with several combinations of laser power and scanning velocity. Electron backscattered diffraction (EBSD) mapping facilitated identification of new orientations, i.e., “stray grains” that nucleated within the fusion zone along with their area fraction and spatial distribution. Using high-fidelity computational fluid dynamics simulations, both the temperature and fluid velocity fields within the melt pool were estimated. This information was combined with a nucleation model to determine locations where nucleation has the highest probability to occur in melt pools. In conformance with general experience in metals additive manufacturing, the as-solidified microstructure of the laser-melted tracks is dominated by epitaxial grain growth; nevertheless, stray grains were evident in elongated melt pools. It was found that, though a higher laser scanning velocity and lower power are generally helpful in the reduction of stray grains, the combination of a stable keyhole and minimal fluid velocity further mitigates stray grains in laser single tracks.

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Repair of Ni-based single-crystal superalloys using vacuum plasma spray

Cited by 16 publications

References 36 publications

Thermal Spray Processes for the Repair of Gas Turbine Components

Thermal Spray Processes for the Repair of Gas Turbine Components

In Situ Generation of TiCN Ni‐Based Coatings by Laser Cladding and Study of Their Structure and Properties

Quantifying Equiaxed vs Epitaxial Solidification in Laser Melting of CMSX-4 Single Crystal Superalloy

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