| Creep Curves of an Aluminium Matrix Composite Reinforced With Continuous Alumina Fibres |
92 |
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| Authors:
K. Matsuura; M. Chou; N. Matsuda; T. Endo; YAMAGATA UNIV YONEZAWA (JAPAN)
|
 | Creep curves of an aluminium matrix composite reinforced with continuous alumina fibers, which were obtained at various stress levels and temperatures between 573 and 773 k, were analytically examined. most of the creep curve at high stress could be approximately expressed by logarithmic creep; this type of creep may be associated with the exponential creep law of the aluminium matrix. |
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| Hydrothermal Corrosion of Magnesia-Partially-Stabilized Zirconia |
91 |
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| Authors:
T. Sato; T. Endo; M. Shimada; T. Mitsudome; N. Otabe; TOHOKU UNIV SENDAI (JAPAN)
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| Changes in the phase composition and microstructures of magnesia- partially-stabilized zirconia (Mg-PSZ) were studied in water at 80-300C, 1M HCl solutions at 80-140C and 1M CH3COOH-CH3COONa buffer solutions at pH 3 and 80- 140C for 10-40 days. The tetragonal to monoclinic phase transformation and the degradation of the fracture strength occurred in water above 200C. On the other hand, although no noticeable tetragonal to monoclinic phase transformation proceeded in 1M ... |
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| Corrosion of Silicon Nitride Ceramics Under Hydrothermal Conditions |
91 |
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| Authors:
T. Sato; T. Murakami; T. Endo; M. Shimada; K. Komeya; TOHOKU UNIV SENDAI (JAPAN)
|
| Corrosion behavior of Si3N4 ceramics containing Y2O3, Al2O3 and AlN as sintering aids was investigated under hydrothermal conditions at 200-300 C and saturated vapor pressures of water for 1-10 days. Hydrothermal corrosion resulted in the dissolution of the Si3N4 matrix and the formation of a product layer consisting of the original grain-boundary phases and hydrated silica. The dissolution rate of Si3N4 ceramics decreased with decreasing crystallinity of the grain boundary ... |
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| Corrosion of Si(sub 3)N(sub 4) and Sialons in V(sub 2)O(sub 5) Melts |
FEB 90 |
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| Authors:
T. Sato; S. Terauchi; T. Endo; M. Shimada
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| Silicon nitride-based ceramics such as hot isostatically pressed silicon nitride, hot pressed silicon nitride, hot pressed sialons containing 0, 30, 60 and 100% of alpha phase were corroded by V(sub 2)O(sub 5) melts at 700 to 1000 C. These silicon nitride-based ceramics were oxidized to silica and dissolved into V(sub 2)O(sub 5) melts. The surface chemical reaction controlled shrinking core model adequately described the relationship between the weight loss of ... |
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| Grain-Size Dependence of Thermal-Shock Resistance of Yttria-Doped Tetragonal Zirconia Polycrystals |
90 |
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| Authors:
M. Ishitsuka; T. Sato; T. Endo; M. Shimada; H. Ohno; TOHOKU UNIV SENDAI (JAPAN)
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| Thermal-shock fracture behavior of yttria-doped tetragonal zirconia polycrystals (Y-TZP) of various grain sizes was evaluated by the quenching method using water as the quenching solvent. The tetragonal-to-monoclinic phase transformation behavior of Y-TZP around cracks introduced by thermal stress was investigated by using Raman microprobe spectroscopy. The critical quenching temperature difference increased with increasing grain size, while fracture strength decreased. Flexural strength, fracture toughness, and grain size are also given in ... |
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| Thermal Shock Fracture Behaviour of ZrO(sub 2) Based Ceramics |
NOV 89 |
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| Authors:
M. Ishitsuka; T. Sato; T. Endo; M. Shimada
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| Thermal shock fracture behavior of alumina, mullite, silicon carbide, silicon nitride and various kinds of zirconia based ceramics, such as magnesia partially stabilized zirconia (Mg-PSZ), yttria and ceria doped tetragonal zirconia polycrystals (Y-TZP and Ce-TZP), Y-TZP/alumina composites and yttria doped cubic stabilized zirconia (Y-CSZ), was evaluated by the quenching method using water, methyl alcohol and glycerin as quenching media. Thermal shock fracture of all materials seemed to proceed by the ... |
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| Improvement of Superplasticity by Deformation Under Increasing Temperature Condition in a 7475 Aluminum Alloy |
NOV 89 |
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| Authors:
N. Muramatsu; Y-e. Hong; T. Endo
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| Superplastic elongation, and the changes in microscopic features and (111) pole figures with strain were investigated on an as-warm rolled 7475 aluminum alloy deformed under various increasing temperature conditions. The optimum condition for superplasticity had a deformation temperature of about 770K. The initial strain rate was 0.001/s and the starting deformation temperature was 590 K. The maximum elongation obtained under the above condition was 965%. This is much greater than ... |
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| Grain Refinement and Mechanical Characteristics at Elevated Temperatures in 7475 Aluminum Alloy Sheets |
AUG 89 |
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| Authors:
Y-e. Hong; N. Muramatsu; T. Endo
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| The effects of testing temperature, imposed strain rate, heating rate up to testing temperature and holding time before stretching on the total plastic strain have been investigated in warm-rolled 7475 aluminum alloy sheets. The value of strain rate sensitivity parameter and apparent activation energy for plastic flow were also measured. Mechanical characteristic and optical microscopic observations showed that in order to take large superplastic elongation the specimens should be heated ... |
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| Raman Microprobe Spectroscopic Studies on Thermal Shock Fracture of ZrO(sub 2)-Based Ceramics |
JUN 89 |
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| Authors:
M. Ishitsuka; T. Sato; T. Endo; M. Shimada; H. Arashi
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| The Raman microprobe spectrum around the crack introduced by thermal stress in Mg-PSZ was almost identical to that around the indentation crack. These results indicate that the tetragonal-to-monoclinic phase transformation was caused by both the mechanical stress and thermal stress in Mg-PSZ. On the other hand, the Raman spectra around the cracks introduced by thermal stress in 2Y-TZP and 2Y-TZP-40 wt.% alumina showed much smaller peaks of the monoclinic phase ... |
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| Postsintering Hot Isostatic Pressing of Ceria-Doped Tetragonal Zirconia/ Alumina Composites in an Argon-Oxygen Gas Atmosphere |
MAY 89 |
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| Authors:
T. Sato; T. Endo; M. Shimada
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| Ceria-doped tetragonal zirconia (Ce-TZP)/alumina composites were fabricated by sintering at 1450 to 1600 C in air, followed by hot isostatic pressing (postsintering hot isostatic pressing) at 1450 C and 100 MPa in an 80 vol% Ar-20 vol% oxygen gas atmosphere. Dispersion of alumina particles into Ce- TZP was useful in increasing the relative density and suppressing the grain growth of Ce-TZP before hot isostatic pressing, but improvement of the fracture ... |
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| Corrosion of Silicon Nitride Ceramics in Aqueous HF Solutions |
OCT 88 |
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| Authors:
T. Sato; Y. Tokunaga; T. Endo; M. Shimada; K. Komeya
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| The leaching behaviors of hot-pressed silicon nitride ceramics containing yttria, alumina and AlN as additives and hot isostatically pressed silicon nitride without additives were studied in 0.1 to 10 M HF aqueous solutions at 50 to 80 C for up to 240 hours. Silicon and aluminum ions were dissolved into the HF solutions, but yttrium ion did not dissolve at all and formed insoluble YF(sub 3). The dissolution of silicon ... |
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| High Temperature Corrosion and Degradation in Strength of Silicon Nitride Based Ceramics by Alkali Sulfates and Carbonates Melts |
88 |
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| Authors:
M. Shimada; T. Sato; T. Endo; TOHOKU UNIV SENDAI (JAPAN)
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| Si3N4 based ceramics such as hot isostatically pressed Si3N4, hot pressed Si3N4, hot pressed sialons containing 0, 30, 60 and 100% of alpha phase were corrodeed by K2SO4 and K2CO3 melts at 1150-1300 C and 925-1150 C, respectively. The minimum reactant molar ratios of K2SO4/Si3N4 and K2CO3/Si3N4 necessary for complete reactions in a nitrogen gas were 1.6 and 3.5, respectively. The surface chemical reaction controlled shrinking core model adequately described ... |
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| High-Temperature Oxidation of Silicon Nitride-Based Ceramics by Water Vapour, |
JUL 1987 |
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| Authors:
T. Sato; K. Haryu; T. Endo; M. Shimada
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| Hot-pressed silicon nitride, sintered silicon nitride and three kinds of sialon with different compositions were oxidized in dry air and wet nitrogen gas atmospheres at 1100 to 1350 C and 1.5 to 20 kPa water vapor pressure. All samples were oxidized by both dry air and water vapor at high temperature, and formed oxide films consisting of silica, Y(sub 2)Si(sub 2)O(sub 7) and Y(sub 4)Al(sub 2)O(sub 9). The oxidation rate ... |
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| HIGH TEMPERATURE OXIDATION OF HOT-PRESSED ALUMINIUM NITRIDE BY WATER VAPOUR, |
JUN 1987 |
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| Authors:
T. Sato; K. Haryu; T. Endo; M. Shimada
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| Hot pressed AlN without additives was oxidized at 1100 to 1400 C in dry air, wet air and wet nitrogen gas atmospheres with 1.5 to 20 kPa of water vapor pressure. AlN was oxidized by both air and water vapor, and formed alpha-alumina film on the surface above 1150 C. The oxidation kinetics in air were parabolic and were promoted by water vapor. On the other hand, the oxidation kinetics ... |
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| THERMAL STABILITY AND MECHANICAL PROPERTIES OF YTTRIA-DOPED TETRAGONAL ZIRCONIA POLYCRYSTALS WITH DISPERSED ALUMINA AND SILICON CARBIDE PARTICLES, |
MAR 1987 |
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| Authors:
T. Sato; H. Fujishiro; T. Endo; M. Shimada
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| Yttria-doped tetragonal zirconia polycrystals in which were dispersed various amounts of alumina and SiC particles were sintered at 1500 C for 3 h, and the mechanical properties and the thermal stability of the sintered bodies were evaluated. Dispersion of alumina caused no significant effect on sinterability, and increased the hardness and elasticity of the composites. Dispersion of SiC particles decreased the relative density and the grain size of composites. Elasticity ... |
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| Relation Between Tensile Strength and Hardness of Aluminum Alloys, |
JAN 1986 |
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| Authors:
S. Sato; T. Endo
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| Tensile and Vickers and Rockwell hardness tests were carried out on a number of aluminum wrought alloys. The alloys are classified into three groups according as the relation between tensile strength and Vickers hardness. A chart for converting hardness to tensile strength is shown. |
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| Strain Rate Effects on the Low Cycle Fatigue Strength of 304 Stainless Steel in High Temperature Water Environment |
86 |
|
| Authors:
M. Fujiwara; T. Endo; H. Kanasaki; MITSUBISHI HEAVY INDUSTRIES LTD TAKASAGO (JAPAN)*
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| A new technique of low cycle fatigue tests in high temperature water, without autoclaves, was developed. Using this technique, effects of dissolved oxygen (D.O.), sensitization and strain rate on the low cycle fatigue life of 304 stainless steel (S.S.) in 300 C water were investigated. In high D.O. water, the fatigue life of sensitized steel was remarkably sensitive to strain rate, but not so much in low D.O. water. The ... |
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| Improvement of Thermal Stability of Yttria-Doped Tetragonal Zirconia Polycrystals by Alloying with Various Oxides, |
1986 |
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| Authors:
T. Sato; S. Ohtaki; T. Endo; M. Shimada
|
| Yttria-doped tetragonal zirconia polycrystals doped with 0-12 mol% of CaO, MgO, ceria and titanium dioxide were sintered at 1400-1600 C for 3 h, and the mechanical properties and thermal stability of the sintered bodies were evaluated. The degree of the tetragonal-to-monoclinic phase transformation by annealing in humid air or hot water decreased with both increasing amounts of ceria or titanium dioxide and decreasing grain size of zirconia. Alloying with titanium ... |
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| The Deviation from Creep by Viscous Glide in Solid Solution Alloys at High Stresses--I. Characteristics of the Dragging Stress |
NOV 84 |
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| Authors:
T. Endo; T. Shimada; T. G. Langdon
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| Solid solution alloys exhibit a clear deviation from creep by viscous glide at high stress levels, and this behavior may be interpreted in terms of the break-away of dislocations from their solute atmospheres. Detailed calculations are described to determine the magnitude of the dragging stress over a wide range of dislocation velocities. The results show that the critical velocity at break-away, V(sub er), is in excellent agreement with the value ... |
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| Effect of Duration of Test Load upon Hardness and Room-Temperature Creep Test for Aluminum Alloys |
JAN 84 |
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| Authors:
H. Kobayashi; S. Sato; T. Endo
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| Vickers hardness tests were carried out for various aluminum alloys under the condition that the duration of loading was changed. To determine the relation between hardness and creep properties, creep tests were carried out at room-temperature. Hardness values of 1000 and 3000 series alloys lower with the increase of the duration of loading and the effects of duration on strongly work-hardened materials are more pronounced. However, hardness values of the ... |
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| High Temperature Deformation of an Al-5 at% Mg Alloy under Combined High Frequency Stresses |
AUG 82 |
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| Authors:
T. Endo; M. Tasaki; M. Kubo; T. Shimada
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| Static flow stress decreases abruptly when ultrasonic oscillatory stress (17.8 kHz) is intermittently superimposed. The decrement in static flow stress was measured in an Al-5Mg alloy. The ranges of strain rate and testing temperature were from 0.0001 to 0.001/S and from 473 to 673 K, respectively. The static flow stress decrement was zero at 673 K. This implies that dislocation velocity at 673 K is proportional to effective stress. The ... |
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| Recovery and Work Hardening Rates of an Al-10 Mass % Zn Solid Solution Alloy at Temperatures from 523 to 823 K |
DEC 81 |
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| Authors:
T. Endo; N. Marumo
|
| The stress and temperature dependence of steady state creep rates, recovery rates and work hardening rates were studied. The rate controlling mechanism changed from bulk to core-diffusion at about 673 K. Application of the Yoshinaga's discriminant revealed that the effective stress level of flow stess is negligibly small. |
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| Decrease in Static Flow Stress of Aluminum by Superimposition of Ultrasonics |
DEC 80 |
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| Authors:
T. Endo; Y. Ibaraki; M. Tasaki
|
| The change in static flow stress caused by superimposed ultrasonics (17.8 kHz) during testing was studied at 77 and 300 K under the strain rates and oscillatory stress amplitudes from 0.0000083 to 0.00083/s and from 0.2 to 11 MPa respectively. The temperature rise due to application of ultrasonics is smaller than 6 K, when the application time is less than 10 s. The decrements in static flow stress are independent ... |
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| Effects of Small Defects on Fatigue Strength of Metals |
JAN 80 |
|
| Authors:
Y. Murakami; T. Endo
|
| Low carbon (0.13C-0.47Mn-0.28Si) and medium carbon (0.46C-0.74Mn-0. 27Si) steel specimens were fatigue tested and the effects of small (40 to 200 micrometers) artificial defects were determined. The smallest holes did not reduce the fatigue limit significantly. |
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| Operating Experience of Precision Forged Titanium Turbine Blades |
80 |
|
| Authors:
A. Okubo; M. Kishimoto; T. Endo; J. Sano; T. Hiwatashi; KOBE STEEL LTD (JAPAN)*
|
| The authors introduced an application of Ti-6Al-4V and Ti-15Mo-5Zr alloy to steam turbine blades. The remarkable findings were revealed from the manufacturing stage, the field tests and the operating experience. Ti-15Mo-5Zr alloy for overlaying showed good erosion resistance in water-drop jet condition. Damping value of blades was much higher than that of the material damping itself. Precise forging of titanium blades could easily be done by using proper beta-forging process. ... |
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| MONOTONIC AND COMPLETELY REVERSED CYCLIC STRESS-STRAIN AND FATIGUE BEHAVIOR OF REPRESENTATIVE AIRCRAFT METALS. |
JUN 1966 |
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| Authors:
T. Endo; JoDean Morrow; ILLINOIS UNIV URBANA DEPT OF THEORETICAL AND APPLIED MECHANICS
|
| Monotonic and cyclic stress-strain and fatigue behavior in the life range of approximately 10 to 100,000 cycles are experimentally determined for 2024-T4 and 7075-T6 aluminum alloys, SAE 4340 steel (quenched and tempered at 1000F), and titanium alloy 8-1-1. The purpose of the investigation is to establish the necessary materials information and base line fatigue data for cumulative damage studies. Plots of the fatigue life as function of elastic, plastic and ... |
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| Existence of the Coaxing Effect and Effects of Small Artificial Holes on Fatigue Strength of an Aluminum Alloy and 70-30 Brass |
|
|
| Authors:
Y. Murakami; Y. Tazunoki; T. Endo
|
| In order to study the existence of the coaxing effect and the effects of small defects on the fatigue strength of an aluminum alloy and 70-30 brass, plain specimens and special holed specimens containing one or more very small drilled holes with diameters of 40, 50, 100, 200, and 500 microns were prepared. Contrary to commonly accepted knowledge, the existence of a distinct coaxing effect was confirmed in the fatigue ... |
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| Creep-Fatigue Life Prediction Using Simple High-Temperature Low-Cycle Fatigue Testing Machines |
|
|
| Authors:
T. Endo; T. Sakon
|
| Several criteria have been proposed for the fracture caused by creep- fatigue interaction and many studies are still being made to verify the validity of these criteria. Most of the studies, however, are based on data obtained by short-time tests. A simple high-temperature low-cycle fatigue testing machine for long-time creep-fatigue tests has been developed and experiments on two kinds of Cr-Mo-V steel forgings and 304 stainless steel plate carried out. ... |
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Reports by Author
