Uniaxial time-dependent ratcheting behavior of bronze powder filled polytetrafluoroethylene at room and high temperature

2013 ◽  
Vol 54 (7) ◽  
pp. 1571-1578 ◽  
Author(s):  
Wenjuan Xu ◽  
Hong Gao ◽  
Lilan Gao ◽  
Jianhua Ma ◽  
Xu Chen
Keyword(s):  
High Temperature ◽  
Time Dependent ◽  
Bronze Powder

The Microstructure and Mechanical Properties of Ni-Based Superalloy after Service Exposure in Gas Turbine

2010 ◽  
Vol 654-656 ◽  
pp. 2523-2526 ◽  
Author(s):  
Keun Bong Yoo ◽  
Han Sang Lee
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
Mechanical Tests ◽  
Time Dependent ◽  
Second Stage ◽  
Degradation Analysis ◽  
Check Points ◽  
Tcp Phase ◽  
Service Exposure ◽  
High Temperature Tensile

Many investigations about superalloys and coatings have been done in the laboratory, but evaluating the degradation condition of hot section components during service is still important not only for repair and reuse but also for outage prevention. Time dependent degradation for second stage blades of gas turbine was investigated. The degradation analysis for used blades was divided into microstructure changes by position of the blade and mechanical tests of high temperature tensile test. In the microstructure analysis, the rafting and coarsening of γ', MC decomposition and TCP phase formation occurred and progressed with increasing service time, and especially the leading and trailing edge of top layer should be a check points for used blade. High temperature tensile results of 25,000 and 52,000 hrs used blades were also compared with serviced time and position in each blade.

scholarly journals Internal Friction and Dynamic Modulus in Ultra-High Temperature Ru-Nb Functional Intermetallics / Tarcie Wewnętrzne I Moduł Dynamiczny W Bardzo Wysoko Temperaturowych Funkcjonalnych Związkach Międzymetalicznych Z Układu Ru-Nb

2015 ◽  
Vol 60 (4) ◽  
pp. 3069-3072
Author(s):  
M.L. Nó ◽  
L. Dirand ◽  
A. Denquin ◽  
J. San Juan
Keyword(s):  
High Temperature ◽  
Internal Friction ◽  
Martensitic Transformations ◽  
Time Dependent ◽  
Structural Defects ◽  
Complete Analysis ◽  
Internal Friction Peak ◽  
Thermally Activated ◽  
Temperature Ranges ◽  
Lower Temperature

In the present work we have studied the high-temperature shape memory alloys based on the Ru-Nb system by using two mechanical spectrometers working in temperature ranges from 200 to 1450ºC and -150 to 900ºC. We have studied internal friction peaks linked to the martensitic transformations in the range from 300 to 1200ºC. In addition, we have evidenced another internal friction peak at lower temperature than the transformations peaks, which apparently exhibits the behaviour of a thermally activated relaxation peak, but in fact is a strongly time-dependent peak. We have carefully studied this peak and discussed its microscopic origin, concluding that it is related to the interaction of some structural defects with martensite interfaces. Finally, we perform a complete analysis of the whole internal friction spectrum, taking into account the possible relationship between the time-dependent peak and the martensitic transformation behaviour.

Local moments, diamagnetism, and time‐dependent magnetic response of high‐temperature superconductors

1988 ◽  
Vol 64 (10) ◽  
pp. 5812-5814 ◽  
Author(s):  
M. Földeáki ◽  
M. E. McHenry ◽  
G. Kalonji ◽  
R. C. O’Handley
Keyword(s):  
High Temperature ◽  
High Temperature Superconductors ◽  
Time Dependent ◽  
Magnetic Response ◽  
Local Moments

Aspects of the Shi–Seinfeld–Okuyama theory of transient nucleation

1995 ◽  
Vol 10 (7) ◽  
pp. 1674-1679 ◽  
Author(s):  
G. Sundar ◽  
J.J. Hoyt
Keyword(s):  
High Temperature ◽  
Singular Perturbation ◽  
Incubation Time ◽  
Cluster Size ◽  
Analytic Solution ◽  
Time Dependent ◽  
Transient Kinetics ◽  
High Temperature Anneal ◽  
Transient Nucleation

The analytic solution to the time-dependent nucleation problem by Shi-Seinfeld-Okuyama (SSO) [Phys. Rev. A 41, 2101 (1990)] is reviewed. The singular perturbation solution employed by SSO is extended to examine the effect of initial quench position on the incubation time. Two cases are discussed. The first investigates the role of excess vacancies from the high temperature quench on the transient kinetics. The second case examines the change in the incubation time due to the effects of a preexisting subcritical cluster size distribution which forms during the high temperature anneal.

scholarly journals Time and Cycle Dependence in High Temperature Fatigue of Ceramic Matrix Composites

1996 ◽  
Author(s):  
Marc Steen ◽  
José-Lorenzo Vallés
Keyword(s):  
High Temperature ◽  
Ceramic Matrix Composites ◽  
Ceramic Matrix ◽  
Fatigue Behaviour ◽  
Time Dependent ◽  
Matrix Composites ◽  
Fibre Failure ◽  
High Temperature Fatigue ◽  
Stress Ratios ◽  
Cyclic Damage

The high temperature fatigue behaviour of two 2D reinforced ceramic matrix composites (CMCs) Is studied under high vacuum conditions. The mechanical loads imposed result in matrix cracking upon first loading, so that continued cyclic loading results in progressive interfacial debonding and/or matrix crack multiplication, as well as fibre failure. In order to investigate whether the fatigue life is mainly governed by time-dependent creep or by cyclically induced fatigue damage, a range of frequencies and two stress ratios are explored in stress controlled fatigue tests. The results obtained indicate that under pulsating fatigue (positive stress ratios or tension-tension) the material response is affected by both creep and fatigue mechanisms. The cyclic damage component gains in relative importance with increasing test frequency. Under reversed loading conditions (negative stress ratios), and depending on the creep strength mismatch between the fibres and the matrix, the time-dependent damage component can be largely suppressed, and the composite fatigue behaviour can become close to purely cycle-dependent. In both cases and for both composites fatigue failure is triggered by fibre failure.

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