Shark-skin inspired surface engineering on intermetallic titanium aluminides for high temperature applications using the fluorine effect

2011 ◽  
Vol 1295 ◽  
Author(s):  
Raluca Pflumm ◽  
Michael Schütze
Keyword(s):  
High Temperature ◽  
Surface Engineering ◽  
Titanium Aluminides ◽  
Single Digit ◽  
New Developments ◽  
Shark Skin ◽  
The Stability ◽  
Micro Structures ◽  
Temperature Applications

ABSTRACTIncreasing demands on technical components for high-temperature applications (e.g. tur-bine blades) promote new developments not only in the field of alloy design, but also in surface engineering. This paper shows that it is possible to structure the surface of intermetallic titanium aluminides in-situ by locally controlled oxidation of the material due to selective doping with fluorine. The aim is to reproduce a shark-skin pattern (parallel riblets with valleys in between) in order to improve the surface aerodynamics. Riblets with widths in the single digit μm range have been generated. The nucleation process, the aspect ratio and the stability of the generated micro-structures are discussed as a function of the substrate composition and the oxidation conditions.

High-sensitivity in situ QCLAS-based ammonia concentration sensor for high-temperature applications

2016 ◽  
Vol 122 (7) ◽  
Author(s):  
W. Y. Peng ◽  
R. Sur ◽  
C. L. Strand ◽  
R. M. Spearrin ◽  
J. B. Jeffries ◽  
...  
Keyword(s):  
High Temperature ◽  
High Sensitivity ◽  
Ammonia Concentration ◽  
Temperature Applications

Stability of TaC precipitates in a Co–Re-based alloy being developed for ultra-high-temperature applications

2016 ◽  
Vol 49 (4) ◽  
pp. 1253-1265 ◽  
Author(s):  
Ralph Gilles ◽  
Debashis Mukherji ◽  
Lukas Karge ◽  
Pavel Strunz ◽  
Premysl Beran ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Gas Turbines ◽  
Volume Fraction ◽  
Turbine Blades ◽  
Alloy Development ◽  
Carbide Phases ◽  
Ultra High Temperature ◽  
Temperature Applications

Co–Re alloys are being developed for ultra-high-temperature applications to supplement Ni-based superalloys in future gas turbines. The main goal of the alloy development is to increase the maximum service temperature of the alloy beyond 1473 K,i.e.at least 100 K more than the present single-crystal Ni-based superalloy turbine blades. Co–Re alloys are strengthened by carbide phases, particularly the monocarbide of Ta. The binary TaC phase is stable at very high temperatures, much greater than the melting temperature of superalloys and Co–Re alloys. However, its stability within the Co–Re–Cr system has never been studied systematically. In this study an alloy with the composition Co–17Re–23Cr–1.2Ta–2.6C was investigated using complementary methods of small-angle neutron scattering (SANS), scanning electron microscopy, X-ray diffraction and neutron diffraction. Samples heat treated externally and samples heatedin situduring diffraction experiments exhibited stable TaC precipitates at temperatures up to 1573 K. The size and volume fraction of fine TaC precipitates (up to 100 nm) were characterized at high temperatures within situSANS measurements. Moreover, SANS was used to monitor precipitate formation during cooling from high temperatures. When the alloy is heated the matrix undergoes an allotropic phase transformation from the ∊ phase (hexagonal close-packed) to the γ phase (face-centred cubic), and the influence on the strengthening TaC precipitates was also studied within situSANS. The results show that the TaC phase is stable and at these high temperatures the precipitates coarsen but still remain. This makes the TaC precipitates attractive and the Co–Re alloys a promising candidate for high-temperature application.

scholarly journals Laser Additive Manufacturing of Intermetallic Alloys for High-Temperature Applications

2021 ◽  
Author(s):  
Silja-Katharina Rittinghaus ◽  
Janett Schmelzer ◽  
Markus B. Wilms ◽  
Manija Kruger
Keyword(s):  
High Temperature ◽  
Additive Manufacturing ◽  
Titanium Aluminides ◽  
Intermetallic Alloys ◽  
Laser Additive Manufacturing ◽  
Direct Energy Deposition ◽  
Direct Energy ◽  
Rapidly Solidified ◽  
Process Composition ◽  
Temperature Applications

Intermetallic alloys like e.g. Iron-Aluminides, Titanium-Aluminides or Molybdenum- Silizides are prospective materials for high-temperature applications. For additive manufacturing (AM) intermetallic structural materials are particularly challenging due to their high melting points, oxygen susceptibility and low temperature brittleness. The feasibility of manufacturing intermetallic Mo-Si-B alloys with the laser additive manufacturing process of direct energy deposition (DED) is demonstrated and recent results in characterizing rapidly solidified material with respect to correlations between process, composition and microstructures are presented. The possibility to dope the material with Yttrium oxide (Y2O3) for dispersion is successfully demonstrated. Current challenges, e.g. homogenous distribution of alloying elements and applicability are addressed.

Characteristics of Gold Wire Bonds with Ti- and Ni-Based Contact Metallization to n-SiC for High Temperature Applications

2010 ◽  
Vol 645-648 ◽  
pp. 745-748 ◽  
Author(s):  
M. Guziewicz ◽  
Ryszard Kisiel ◽  
Krystyna Gołaszewska ◽  
Marek Wzorek ◽  
Anna Stonert ◽  
...  
Keyword(s):  
High Temperature ◽  
Ohmic Contacts ◽  
Gold Wire ◽  
Electrical Parameters ◽  
Contact Metallization ◽  
Wire Bonds ◽  
Morphology And Structure ◽  
The Stability ◽  
Temperature Applications

The stability of Au wire connections to n-SiC/Ti ohmic contacts and to n-SiC/Ni ohmic contacts with top Au or Pt layers has been investigated. Long-term tests of the connections are performed in air at 400oC. Evaluation of electrical parameters, morphology and structure of the metallization as well as the strength of Au joint show stable Au wire bonds to the metallization with Ti-ohmic contacts.

Creep Properties of Ti-48Al-2Cr-2Nb Produced by Selective Electron Beam Melting

2016 ◽  
Vol 704 ◽  
pp. 190-196 ◽  
Author(s):  
Vera Juechter ◽  
Carolin Körner
Keyword(s):  
Electron Beam ◽  
High Temperature ◽  
Electron Beam Melting ◽  
Titanium Aluminides ◽  
Turbine Blades ◽  
Weight Ratio ◽  
Cast Material ◽  
Creep Properties ◽  
Selective Electron Beam Melting ◽  
Temperature Applications

Titanium aluminides are highly attractive for high temperature applications involving dynamic components, e.g. turbine blades or turbocharger wheels, due to their high strength-to-weight ratio. The drawback is the difficult manufacturing of this material class due to the low toughness and high sensitivity to oxygen. Selective electron beam melting SEBM shows a new approach of producing complex titanium aluminide parts without a major oxygen pick up and avoiding problems with brittleness. The high cooling rates of this process lead to a very fine microstructure, which is not fully understood up to now. The microstructure determines the creep properties and therefore defines the performance of this material in high temperature applications. In this contribution, the creep properties of Ti-48Al-2Cr-2Nb fabricated by SEBM are investigated. The influence of the processing parameters and the building direction on the microstructure and the creep properties are discussed and compared to cast material.

High-temperature structural study of decagonal Al–Cu–Rh

2014 ◽  
Vol 70 (2) ◽  
pp. 306-314 ◽  
Author(s):  
Pawel Kuczera ◽  
Janusz Wolny ◽  
Walter Steurer
Keyword(s):  
High Temperature ◽  
Single Crystal ◽  
Structural Study ◽  
Structural Disorder ◽  
X Ray Diffraction ◽  
X Ray ◽  
Decagonal Phase ◽  
Comparative Structure ◽  
The Stability

The structure of decagonal Al–Cu–Rh has been studied as a function of temperature byin-situsingle-crystal X-ray diffraction in order to contribute to the discussion on energy or entropy stabilization of quasicrystals. The experiments were performed at 293, 1223, 1153, 1083 and 1013 K. A common subset of 1460 unique reflections was used for the comparative structure refinements at each temperature. A comparison of the high-temperature datasets suggests that the best quasiperiodic ordering should exist between 1083 and 1153 K. However, neither the refined structures nor the phasonic displacement parameter vary significantly with temperature. This indicates that the phasonic contribution to entropy does not seem to play a major role in the stability of this decagonal phase in contrast to other kinds of structural disorder, which suggests that, in this respect, this decagonal phase would be similar to other complex intermetallic high-temperature phases.

scholarly journals Performance of Carbide Alloy Compounds in Carbon Doped MoNbTaW

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1073
Author(s):  
Congyan Zhang ◽  
Uttam Bhandari ◽  
Jialin Lei ◽  
Congyuan Zeng ◽  
Shengmin Guo ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
X Ray Diffraction ◽  
Complex Alloy ◽  
Carbon Doped ◽  
Refractory Elements ◽  
Diamond Anvil ◽  
The Stability ◽  
Bcc Phase

In this work, the performance of the carbon doped compositionally complex alloy (CCA) MoNbTaW was studied under ambient and high pressure and high temperature conditions. TaC and NbC carbides were formed when a large concentration of carbon was introduced while synthesizing the MoNbTaW alloy. Both FCC carbides and BCC CCA phases were detected in the sample compound at room temperature, in which the BCC phase was believed to have only refractory elements MoNbTaW while FCC carbide came from TaC and NbC. Carbides in the carbon doped MoNbTaW alloy were very stable since no phase transition was obtained even under 3.1 GPa and 870 °C by employing the resistor-heating diamond anvil cell (DAC) synchrotron X-ray diffraction technique. Via in situ examination, this study confirms the stability of carbides and MoNbTaW in the carbon doped CCA even under high pressure and high temperature.

A High Performance Power Module with >10kV capability to Characterize and Test In Situ SiC Devices at >200°C Ambient

2016 ◽  
Vol 2016 (HiTEC) ◽  
pp. 000149-000158
Author(s):  
Xin Zhao ◽  
Haotao Ke ◽  
Yifan Jiang ◽  
Adam Morgan ◽  
Yang Xu ◽  
...  
Keyword(s):  
High Temperature ◽  
High Voltage ◽  
High Performance ◽  
Power Module ◽  
Module Design ◽  
Power Modules ◽  
Operational Temperature ◽  
Full Power ◽  
Temperature Applications

Abstract This paper presents design, fabrication and characterization details of a 10kV power module package for >200°C ambient temperature applications. Electrical simulations were performed to confirm the module design, and that the electric field distribution throughout the module did not exceed dielectric capabilities of components and materials. A suitable copper etching process was demonstrated for DBC layout, and a high melting point Sn/Pb/Ag solder reflow process was developed for device and component attachment. To monitor the operational temperature of the module, a thermistor was integrated onto the substrate. A new silicone gel, having a working temperature up to 210°C, was evaluated and selected for encapsulation and, of great importance, for passivation of high voltage (10kV) SiC dies. An additive manufacturing ‘Design Process’ was developed and applied to printing the housings, molds, and test fixtures. Also, cleaning processes were evaluated for every step in the fabrication process. To verify performance of the modules, mechanical dies were mounted on the substrates, and a high temperature testing setup built to characterize the modules at high temperature. Measurements indicated that the module can operate up to 12kV within 25°C to 225°C, with less than 0.1 μA leakage current. The packaging was used for full-power characterization of developmental 10kV SiC diodes, and proved that the power module packaging satisfied all requirements for high voltage and high temperature applications. This work successfully validated the processes for creating high voltage (>10 kV) and high temperature (>200°C) power modules.

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