Addition Of Ru Research Articles

The effects of ruthenium on the phase stability of fourth generation Ni-base single crystal superalloys

Abstract The formation of topologically close-packed (TCP) phases in nickel-base single crystal superalloys causes considerable degradation of the mechanical properties. It has recently been found that platinum-group metals can be effective in controlling the precipitation of such phases, and this extent of precipitation control requires further investigation. This study compares Ru-containing and non-Ru-containing single crystal superalloys. Scanning electron microscopy microstructural observations showed that the rate of TCP phase precipitations decreased through Ru addition. Transmission electron microscopy microstructural observations showed that the P phase, one of the TCP phases, was eliminated through the addition of Ru. The occurrence of this phenomenon will be discussed.

Effects of Ru additions on the microstructure and phase stability of Ni-base superalloy, UDIMET 720LI

The effects of Ru additions on the microstructure and phase stability of the Ni-base superalloy U720LI were examined. The results show that the alloys with Ru contents of 0 to 6 wt pct had a dendritic structure, and the volume fraction of the primary γ solid-solution phase in the dendritic core increased with the increase in the Ru content. The Ru additions to U720LI had little effect on suppressing the formation of the σ phase, because the elemental partitioning of Cr, Mo, and Co in the γ solid-solution phase was not influenced by the Ru additions. However, the coarsening of the γ′ phase was restrained by the Ru additions in the U720LI.

第 2 世代 Ni 基単結晶超合金 TMS-82+へのRe, Ru 複合添加

To improve the creep strength of Ni-base superalloys, Re and Ru additions were investigated with using 2nd generation single crystal superalloy TMS-82+ which contains 2.4 mass%Re, as the base alloy. When Re and Ru were added at the same time, creep strength was improved at lower and higher temperature. We suppose that these were caused by the solution strengthening due to Re at lower temperature, and the stabilization of γ/γ′ structure at higher temperature by Ru addition. Further more, in the case of Re addition, creep strength at lower temperature was improved, and creep strength at higher temperature became worse due to the TCP phase formation. Also, in the case of Ru addition, creep strength at lower and higher temperature became worse, although TCP phase formation was completely suppressed. This is because Ru is not an effective element for the solution strengthening at high temperature.

Alcohol Electrooxidation at Pt-Ru Sputter-deposited Electrode

The use of various alcohols including methanol has been considered as the fuel of direct alcohol fuel cells (DAFCs). Thus far, the Pt alloys have mainly been studied as anode electrocatalysts for DAFCs. Pt itself is poisoned by chemical species produced during the alcohol oxidation. There exist many reports that the addition of Ru is effective for the alcohol oxidation. In this work, we prepared Pt-Ru co-sputtered electrode by changing Ru content, sputtering time and Ar pressure for the sputtering. By using the prepared electrocatalysts, relationships between sputtering conditions and electrocatalytic activity were measured for some alcohols.

耐酸化性とクリープ強度に優れる第5世代Ni基単結晶超合金

The National Institute of Materials Science (NIMS) has utilized the in-house alloy design program to develop a 5th generation Ni-base single crystal superalloy, TMS-196 with superior high temperature creep and oxidation resistance by incorporating further ruthenium (Ru) and chromium (Cr) content over the compositions of 4th generation superalloys. With Ru additions in advanced superalloys to enhance phase stability, higher content of refractory elements can be accommodated to provide further strengthening; the associated oxidation resistance can be improved by the increase in Cr additions. In present article, TMS-196 has been subjected to cyclic/isothermal oxidation tests at 1100°C and creep at conditions between 800°C~1100°C/137 MPa~735 MPa. Preliminary studies indicate that the surface of oxidized TMS-196 can exhibit continuous alumina layer attributing good oxidation resistance similar to that of Rene'N5. Detailed TEM analyses have shown the alloy system of TMS-196 possessing strong resistance to γ′ deformation during creep deformation. Data regarding to oxidation and creep properties of some previous generations of superalloys are also included for comparisons and discussions in this research.

Ni基単結晶耐熱合金の重回帰分析による熱疲労寿命予測

This study was carried out to find out the mechanical properties of nickel-base superalloys that affect thermal mechanical fatigue (TMF). TMF tests and high temperature tensile tests were conducted on 28 of Ni-base single crystal superalloys in order to obtain mechanical property data. Based on the experimental data, Multiple regression analysis was performed for the correlation between the number of TMF cycles to failure and the alloy compositions. The multiple correlation coefficient was found to be R=0.84; this indicates that alloy composition has a considerable relationship with the number of TMF cycles to failure. It was also found that the addition of Co, Ru and Al is effective to improve the TMF property. In addition, another multiple regression analysis was also carried out for the correlation between the number of TMF cycles to failure among high temperature mechanical properties and microstructural parameters.

Ethanol electro-oxidation on carbon-supported Pt, PtRu and Pt 3Sn catalysts: A quantitative DEMS study

The electrocatalytic activity of commercial carbon supported PtRu/Vulcan and Pt 3Sn/Vulcan bimetallic catalysts (E-TEK, Inc.) for ethanol oxidation under well defined electrolyte transport conditions and their selectivity for complete oxidation were evaluated using cyclic voltammetry combined with on-line differential electrochemistry mass spectrometry (DEMS) measurements and compared to the activity/selectivity of standard Pt/Vulcan catalysts. The main reaction products CO 2, acetaldehyde and acetic acid were determined quantitatively, by appropriate calibration procedures, current efficiencies and product yields were calculated. Addition of Ru or Sn in binary Pt catalysts lowers the onset potential for ethanol electro-oxidation and leads to a subtle increase of the total activity of the Pt 3Sn/Vulcan catalyst. It does not improve, however, the selectivity for complete oxidation to CO 2, which is about 1% for all three catalysts under present reaction conditions—incomplete ethanol oxidation to acetaldehyde and acetic acid prevails on all three catalysts. The results demonstrate that the performance of the respective catalysts is limited by their ability for C–C bond breaking rather than by their activity for the oxidation of poisoning adsorbed intermediates such as CO ad or CH x,ad species.

Direct ethanol fuel cell (DEFC): Electrical performances and reaction products distribution under operating conditions with different platinum-based anodes

Ethanol electro-oxidation at different Pt-based electrodes was investigated in a single direct ethanol fuel cell (DEFC) in terms of reaction product distribution depending on the anode catalyst. In DEFC experiments, only three reaction products were detected using HPLC: acetaldehyde (AAL), acetic acid (AA) and CO 2. The addition of tin to platinum increases the activity of the catalyst by several order of magnitude and the electrical performance of the DEFC are greatly enhanced from a few mW cm −2 to 30 mW cm −2 at 80 °C, with Pt/C and Pt–Sn/C catalysts, respectively. Moreover, at Pt–Sn/C and Pt–Sn–Ru/C the formation of CO 2 and AAL is lowered whereas the formation of AA is increased in comparison to what happens at a Pt/C catalyst. The addition of Ru to Pt–Sn only leads to enhance the electrical performance of the DEFC, i.e. the activity of the catalyst, but does not modify the product distribution. Very good stability in the open circuit voltage of the DEFC (close to 0.75 V) was observed over a period of 2 weeks at 90 °C, the cell undergoing start-run-stop cycles each day. Good stability under operating conditions at a given current density was also observed over 6 h.

Cys-tRNAPro Editing by Haemophilus influenzae YbaK via a Novel Synthetase·YbaK·tRNA Ternary Complex

Aminoacyl-tRNA synthetases are multidomain enzymes that often possess two activities to ensure translational accuracy. A synthetic active site catalyzes tRNA aminoacylation, while an editing active site hydrolyzes mischarged tRNAs. Prolyl-tRNA synthetases (ProRS) have been shown to misacylate Cys onto tRNA(Pro), but lack a Cys-specific editing function. The synthetase-like Haemophilus influenzae YbaK protein was recently shown to hydrolyze misacylated Cys-tRNA(Pro) in trans. However, the mechanism of specific substrate selection by this single domain hydrolase is unknown. Here, we demonstrate that YbaK alone appears to lack specific tRNA recognition capabilities. Moreover, YbaK cannot compete for aminoacyl-tRNAs in the presence of elongation factor Tu, suggesting that YbaK acts before release of the aminoacyl-tRNA from the synthetase. In support of this idea, cross-linking studies reveal the formation of binary (ProRS.YbaK) and ternary (ProRS.YbaK.tRNA) complexes. The binding constants for the interaction between ProRS and YbaK are 550 nM and 45 nM in the absence and presence of tRNA(Pro), respectively. These results suggest that the specificity of trans-editing by YbaK is ensured through formation of a novel ProRS.YbaK.tRNA complex.

Measurement of hydrogen permeability of pure Nb and its alloys by electrochemical method

Niobium metal is one of the promising materials for hydrogen permeable membranes because of the highest hydrogen permeability among the 5A group metals including V and Ta. In the present study, using a limiting current method, the hydrogen permeability was measured precisely for the first time with pure Nb and Nb–5 mol%M binary alloys. Here, M were 4d transition metals, Zr, Mo, Ru and Pd. The measured hydrogen permeability of pure Nb agreed well with the value calculated from the diffusion coefficient and the hydrogen solubility. Also, it was found that the hydrogen permeability of niobium increased by the addition of Zr and Pd, but decreased by the addition of Mo and Ru.

Synergetic effects of Pt and Ru added to Mo/Al 2O 3 sulfide catalyst in simultaneous hydrodesulfurization of thiophene and hydrogenation of cyclohexene

The effect of Pt and Ru (∼0.6%) added to Mo/Al 2O 3 sulfide catalyst on the simultaneous hydrodesulfurization (HDS) of thiophene and hydrogenation (HYD) of cyclohexene was studied. The addition of Pt and Ru significantly increased the HDS and HYD activities of the Mo/Al 2O 3 catalyst. The addition of Pt led to a weaker synergy in HDS, which was almost independent of the reaction temperature. The addition of Ru led to much stronger synergy in both reactions, which increased at higher reaction temperatures. The synergy in HDS over Ru-promoted catalyst occurred between 240 and 320 °C, approaching values of up to 6. The strong synergy in HYD (up to 4) appeared only at temperatures 300–330 °C and was accompanied by a more than twofold increase in the apparent activation energy. As the most probable explanation, a change in the quality of the sites participating in HYD was proposed. HYD mainly proceeds on separate Ru and Mo sulfides at lower temperatures and while on mixed Ru–Mo–S sites at above 300 °C. This change is ascribed to a partial release of Ru–Mo–S sites by desorption of thiophene or H 2S at the higher temperatures, which compete for the adsorption and reaction with HYD.

Ruthenium Complexes of Six-Electron-Donor NUPHOS-Type Diphosphines: Highly Selective Catalysts for the Hydrocarboxylation of Terminal Alkynes

The ruthenium-p-cymene complexes [(p-cymene)Ru(1,2,3,4-Me4-NUPHOS)Cl][SbF6] (2a) and [(p-cymene)Ru(1,4-Et2-2,3-cyclo-C6H8-NUPHOS)Cl][SbF6] (2b) have been prepared by reaction of [(p-cymene)RuCl2]2 with the corresponding NUPHOS diphosphine in the presence of NaSbF6. The chloro ligand can be abstracted from these monocations to afford [(p-cymene)Ru(P,P,η2(C)-1,2,3,4-Me4-NUPHOS)][SbF6]2 (3a) and [(p-cymene)Ru(P,P,η2(C)-1,4-Et2-2,3-cyclo-C6H8-NUPHOS)][SbF6]2 (3b), respectively, in which the diphosphine coordinates as a six-electron donor, bonded through both diphenylphosphino groups and one of the double bonds of the butadiene tether. In stark contrast, it proved markedly more difficult to abstract the chloro ligand from either the BIPHEP or the MeO-BIPHEP monocations [(p-cymene)Ru(BIPHEP)Cl][SbF6] (4a) and [(p-cymene)Ru(MeO-BIPHEP)Cl][SbF6] (4b), and even after prolonged reaction times at elevated temperature [(p-cymene)Ru(BIPHEP)][SbF6]2 (5a) and [(p-cymene)Ru(MeO-BIPHEP)][SbF6]2 (5b) formed as a 30% mixture with unreacted 4a and 4b, respectively. The structures of 2a, as its perchlorate salt, and 2b have been determined by single-crystal X-ray crystallography and are compared with that of their BIPHEP counterpart 4a. Unfortunately, it has not been possible to prepare the corresponding dppb complex [(p-cymene)Ru(dppb)Cl][SbF6] to undertake a comparative study, since [(p-cymene)RuCl2]2 reacts with dppb under the same conditions as those used to prepare 2a,b to afford the bridged dimer [{(p-cymene)RuCl2}2(μ-dppb)] (6), the identity of which has been confirmed by a single-crystal X-ray study. Interestingly, 3a undergoes rapid hydrolysis in the presence of pyridine to give [(p-cymene)Ru{Ph2(O)PC(H)MeCMeCMeCMePPh2}][SbF6] (7), which contains an unusual unsymmetrical bisphosphine monoxide pincer ligand formed by oxidation of one of the diphenylphosphino groups of 1,2,3,4-Me4-NUPHOS and a highly regioselective syn addition of Ru and H across the butadiene double bond proximate to the phosphine oxide. Dications 3a,b catalyze the regioselective anti-Markovnikov addition of benzoic acid to 1-pentyne and 1-octyne to give the corresponding alk-1-en-1-yl esters with cis-to-trans ratios as high as 95:5, while the corresponding BIPHEP and MeO-BIPHEP complexes were significantly less selective, catalyst mixtures formed from 4b giving a 70:30 mixture of cis and trans alk-1-en-1-yl ester. In contrast, selectivity was reversed with catalyst mixtures generated from 6, which were 90% selective for Markovnikov addition to 1-octyne, as might have been predicted for a ruthenium catalyst coordinated by a single phosphine, albeit one-half of a bidentate diphosphine. Catalysts based on NUPHOS diphosphines are also highly active and selective for anti-Markovnikov addition of benzoic acid to phenylacetylene and give (Z)-styryl benzoate in yields of up to 85% and selectivities as high as 99:1 with no evidence for the formation of terminal olefin. In our hands, solutions formed by activation of 4a,b with AgSbF6 catalyze the regio- and stereoselective anti-Markovnikov hydrocarboxylation of phenylacetylene, which was somewhat surprising considering that an earlier report has claimed that 5b reacts with phenylacetylene to form a stable catalytically inactive cyclometalation/insertion product.

Alloying Effects on Hydrogen Permeability of Niobium

Niobium metal is one of the promising material for hydrogen purification because of its high hydrogen permeability. In order to design and develop a new palladium-free hydrogen permeable membrane, it is important to understand the effects of alloying elements on the hydrogen permeability through metals. However, to the niobium metal, the alloying effects still remain unclear. In the present study, using a DC-polarization technique under the diffusion limiting condition, the hydrogen permeability of Nb-5mol%M alloys were investigated in high precision at 573K. Here, M’s were 4d transition metals, Zr, Mo, Ru and Pd. The permeability of niobium is found to be varied with the addition of a small amount of alloying element. For example, the hydrogen permeability of niobium increases by the addition of Zr but decreases by the addition of Ru.

Ｒｅを含まない第４世代単結晶超合金

Advanced high-temperature strengths in Ni-base single crystal (SC) superalloys have been achieved through the addition of Re in small amounts. However, Re has a strong tendency to form topologically close-packed (TCP) phases that decrease the creep strength, thus, increasing the Re content has undesirable consequences. This effect of Re addition is controlled in 4th generation superalloys where the formation of TCP phases is avoided by the addition of platinum-group metals (PGMs) such as Ru and Ir, and increased creep strengths have been achieved. Furthermore, PGM elements and solution strengthening elements including Re have been added in 5th generation superalloys to achieve superior high temperature strength. However, because Re is an expensive element and longer homogenization time is required for high-Re alloys, the use of this alloying element results in higher material and production cost, and lower productivity. In this paper, a new type of Ni-base single crystal superalloy is proposed. This alloy does not contain Re but still reaches the high temperature capabilities of 4th and 5th generation superalloys, and has the advantages of low material cost and easy heat treatment. 1st generation single crystal superalloys do not contain Re, therefore, these are suitable material to be used as the master alloy for this alloy development. TMS-26, which was developed through High Temperature Materials 21 Project, NIMS, was used as the master alloy and, by the addition of Mo and Ru, a new single crystal superalloy TMS-174 was developed. Mo has the effect of controlling the lattice misfit and solid solution strengthening. Mo also promotes TCP formation, however this is avoided by the addition of Ru. The creep rupture life of TMS-174 at 900°C and 392 MPa was slightly shorter than that of TMS-138, which is a conventional 4th generation single-crystal superalloy with 5 mass%Ru. However, at 1100°C and 137 MPa, creep rupture life of TMS-174 was found to be 18% longer compared to TMS-138. This new alloy development strategy of adding solid solution strengthening elements and PGM elements to form non-Re containing superalloys was demonstrated to be successful. This strategy has the potential for superior alloy developments in the future because of the benefits of cost reduction and attainable material properties that are comparable to 4th and 5th generation superalloys.

Ｎｉ基単結晶超合金の１０００℃域クリープ強度因子解析

It is important to clarify the parameters which influence the creep rupture life of Ni-base single crystal superalloys under the service condition of jet-engine turbine blades, such as 1000°C/245 MPa. In the most recently developed alloys, Ru is added to suppress the formation of the detrimental Topologically Close Packed (TCP) phases, however, its solid solution strengthening effects have not been clarified yet. In this study, the parameters affecting the creep rupture life of alloys with various compositions were analyzed by a multi regression method, and the results were discussed quantitatively in terms of the chemical composition of the γ′ phase, lattice misfit and volume fraction. It was found that Re, Mo, Ta and W were all effective additions for solid solution strengthening and Re was found to be the most effective under the service condition. In contrast, Ru addition had almost no influence on the strengthening effect. The results enabled the prediction of the creep rupture life of an alloy of a known composition.

Single-Chamber SOFCs with a Ce[sub 0.9]Gd[sub 0.1]O[sub 1.95] Electrolyte Film for Low-Temperature Operation

Single-chamber solid oxide fuel cells (SOFCs) with an anode-supported electrolyte were operated in a mixture of butane and air at furnace temperatures of 200-300°C. The electromotive force (emf) of the cell and the voltage drop were strongly influenced by the catalytic activity of the anode for the partial oxidation of butane. The promotion of hydrogen formation by the addition of Ru to the anode caused an increase in the emf and a reduction in the voltage drop. As a result, stable power densities of 44 and 176 mW cm−2 were obtained at 200 and 300°C, respectively. © 2004 The Electrochemical Society. All rights reserved.

Effects of Ru and Re additions on the high temperature flow stresses of Ni-base single crystal superalloys

The strengthening effects of Re and Ru additions in high refractory content single crystal Ni-base superalloys were investigated. An electro-thermal mechanical testing (ETMT) unit was used to measure the high temperature flow stresses of five experimental Ni-based superalloys containing varying levels of Re and Ru. Flow stresses of single phase γ and γ′ alloys with compositions representative of the constituent phases found in superalloy single crystals were also measured. Significant increases in flow stress were observed with the addition of Ru or Re. For similar alloying levels in wt%, additions of Re were more effective in strengthening the single crystal alloy when compared to addition of Ru.

Surface‐Confined Metalloporphyrin Oligomers

The modular assembly of metalloporphyrin oligomers through the stepwise addition of Ru–porphyrin units and a bidentate linking ligand (L, see graphic) onto a surface-confined isonicotinate ligand is reported. Electrochemical measurements of the resulting oligomer show that electrons are transported along the length of its backbone.

Determining the site occupancy of Ru in the L1 2 phase of a Ni-base superalloy using ALCHEMI

Small additions of Ru significantly improve the high temperature creep properties of Ni-base superalloys, but the mechanism is uncertain. In order to understand the effects of adding Ru it is important to know the atomic site(s) occupied by Ru in the superalloy structure. We used the technique ALCHEMI (Atomic site Location by CHannelling Enhanced MIcroanalysis) on a Ni-base superalloy containing Ru and encountered unexpected problems. We have explained why the ALCHEMI technique cannot accurately be used with Ni-base superalloys. We then successfully applied ALCHEMI to the simpler ternary alloy Ni–19at.%Al–3at.%Ru and found that 60% of the Ru partitions to the Al sublattice in the Ni 3Al γ′ phase giving an absolute atomic site preference of 5:1. Assuming such site preference holds true for more complex alloys, this information can be used to better understand the role that this platinum group metals plays.

Effect of Ru additions on microstructure and mechanical properties of Cr–TaCr 2 alloys

Early work indicated that Ru reduced the ductile-to-brittle transition temperature of Cr even at small concentrations. To evaluate the potential of Ru as a beneficial alloying element in the two-phase Cr–TaCr 2 alloys, a number of Cr–8 at.%Ta alloys with 0–10 at.%Ru were prepared, and their microstructures and mechanical properties were evaluated. The Ru addition was found to move the eutectic point of Cr–TaCr 2 to a higher Ta level, as compared to the binary Cr–Ta system. Ru partitioned preferentially in the Laves phase over in the Cr matrix, with a partitioning ratio of 2–5:1, depending on the Ru addition level. Ru was also found to mainly occupy the Cr site in the TaCr 2 Laves phase. The hardness of both the primary Cr matrix and the eutectic microconstituent increased slightly with the increase in Ru addition. At a higher Ru addition level (i.e. 10 at.%), the hardness of the primary Cr matrix increased significantly, probably due to the precipitation of extremely fine Laves-phase precipitates. The Ru addition did not noticeably affect the fracture toughness of the two-phase alloys.