scholarly journals The effect of cycle frequency, H2O and CO2 on TBC lifetime with NiCoCrAlYHfSi bond coatings

2014 ◽  
Vol 260 ◽  
pp. 107-112 ◽  
Author(s):  
M.J. Lance ◽  
K.A. Unocic ◽  
J.A. Haynes ◽  
B.A. Pint
Keyword(s):  
Cycle Frequency ◽  
Bond Coatings ◽  
Tbc Lifetime

Effect of increased water vapor levels on TBC lifetime with Pt-containing bond coatings

2011 ◽  
Vol 206 (7) ◽  
pp. 1566-1570 ◽  
Author(s):  
B.A. Pint ◽  
G.W. Garner ◽  
T.M. Lowe ◽  
J.A. Haynes ◽  
Y. Zhang
Keyword(s):  
Water Vapor ◽  
Bond Coatings ◽  
Tbc Lifetime

The Effect of Environment on TBC Lifetime

2015 ◽  
Author(s):  
Bruce A. Pint ◽  
Kinga A. Unocic ◽  
J. Allen Haynes
Keyword(s):  
Water Vapor ◽  
Carbon Capture ◽  
Air Plasma ◽  
Combustion Gas ◽  
Bond Coatings ◽  
Barrier Coating ◽  
Coating Failure ◽  
Negative Effect ◽  
Plasma Sprayed ◽  
Tbc Lifetime

While the water vapor content of the combustion gas in natural gas-fired land based turbines is ∼10%, it can be 20–85% with coal-derived (syngas or H2) fuels or innovative turbine concepts for more efficient carbon capture. Additional concepts envisage working fluids with high CO2 contents to facilitate carbon capture and sequestration. To investigate the effects of changes in the gas composition on thermal barrier coating (TBC) lifetime, furnace cycling tests (1 and 100h cycles) were performed in air with 10, 50 and 90 vol.% water vapor and CO2-10%H2O and compared to prior results in dry air or O2. Two types of TBC’s were investigated: (1) diffusion bond coatings (Pt diffusion or Pt-modified aluminide) with commercial electron-beam physical vapor-deposited yttria-stabilized zirconia (YSZ) top coatings on second-generation superalloy N5 and N515 substrates and (2) high velocity oxygen fuel (HVOF) sprayed MCrAlYHfSi bond coatings with air-plasma sprayed YSZ top coatings on superalloys X4, 1483 or 247 substrates. For both types of coatings exposed in 1h cycles, the addition of water vapor resulted in a decrease in coating lifetime, except for Pt diffusion coatings which were unaffected by the environment. In 100h cycles, environment was less critical, perhaps because coating failure was chemical (i.e. due to interdiffusion) rather than mechanical. In both 1h and 100h cycles, CO2 did not appear to have any negative effect on coating lifetime.

scholarly journals The Effect of Coating Composition and Geometry on TBC Lifetime

2017 ◽  
Author(s):  
Bruce A. Pint ◽  
Michael J. Lance ◽  
J. Allen Haynes
Keyword(s):  
Gas Turbines ◽  
Average Lifetime ◽  
Air Plasma ◽  
Bond Coatings ◽  
Bond Coating ◽  
Negative Effect ◽  
Plasma Sprayed ◽  
Oxygen Fuel ◽  
Thermally Sprayed ◽  
Tbc Lifetime

Several factors are being investigated that affect the performance of thermal barrier coatings (TBC) for use in land-based gas turbines where coatings are mainly thermally sprayed. This study examined high velocity oxygen fuel (HVOF), air plasma sprayed (APS) and vacuum plasma sprayed (VPS) MCrAlYHfSi bond coatings with APS YSZ top coatings at 900°–1100°C. For superalloy 247 substrates and VPS coatings tested in 1-h cycles at 1100°C, removing 0.6wt.%Si had no effect on average lifetime in 1-h cycles at 1100°C, but adding 0.3%Ti had a negative effect. Rod specimens were coated with APS, HVOF and HVOF with an outer APS layer bond coating and tested in 100-h cycles in air+10%H2O at 1100°C. With an HVOF bond coating, initial results indicate that 12.5 mm diameter rod specimens have much shorter 100-h cycle lifetimes than disk specimens. Longer lifetimes were obtained when the bond coating had an inner HVOF layer and outer APS layer.

Fatigue of Unidirectional Cord-Rubber Composites

1999 ◽  
Vol 27 (1) ◽  
pp. 48-57 ◽  
Author(s):  
Y. Liu ◽  
Z. Wan ◽  
Z. Tian ◽  
X. Du ◽  
J. Jiang ◽  
...  
Keyword(s):  
Damage Accumulation ◽  
Fatigue Testing ◽  
Fatigue Behavior ◽  
Constant Load ◽  
Testing System ◽  
Rubber Composites ◽  
Cycle Frequency ◽  
Periodic Loading ◽  
Fatigue Damage Accumulation ◽  
Rubber Composite

Abstract A fatigue testing system is established with which the real-time recording of stress, strain, temperature, and hysteresis loss of rubbers or cord-rubber composite specimens subjected to periodic loading or extension can be successfully carried out. Several problems are connected with the experimental study of the fatigue of rubber composites. In constant extension cycling, the specimen becomes relaxed because of the viscoelasticity of rubber composites, and the imposed tension-tension deformation becomes complex. In this method, the specimen is unlikely to fail unless the imposed extensions are very large. Constant load cycling can avoid the shortcomings of constant extension cycling. The specially designed clamps ensure that the specimen does not slip when the load retains a constant value. The Deformation and fatigue damage accumulation processes of rubber composites under periodic loading are also examined. Obviously, the effect of cycle frequency on the fatigue life of rubber composites can not be ignored because of the viscoelasticity of constituent materials. The increase of specimen surface temperature is relatively small in the case of 1 Hz, but the temperature can easily reach 100°C at the 8 Hz frequency. A method for evaluating the fatigue behavior of tires is proposed.

Fatigue of mouse soleus muscle, using the work loop technique.

1997 ◽  
Vol 200 (22) ◽  
pp. 2907-2912 ◽  
Author(s):  
G N Askew ◽  
I S Young ◽  
J D Altringham
Keyword(s):  
Soleus Muscle ◽  
Power Output ◽  
Cycle Frequency ◽  
Reduction In Force ◽  
Negative Work ◽  
Loop Shape ◽  
Force Velocity ◽  
Positive Work ◽  
Work Loop

The function of many muscles requires that they perform work. Fatigue of mouse soleus muscle was studied in vitro by subjecting it to repeated work loop cycles. Fatigue resulted in a reduction in force, a slowing of relaxation and in changes in the force-velocity properties of the muscle (indicated by changes in work loop shape). These effects interacted to reduce the positive work and to increase the negative work performed by the muscle, producing a decline in net work. Power output was sustained for longer and more cumulative work was performed with decreasing cycle frequency. However, absolute power output was highest at 5 Hz (the cycle frequency for maximum power output) until power fell below 20% of peak power. As cycle frequency increased, slowing of relaxation had greater effects in reducing the positive work and increasing the negative work performed by the muscle, compared with lower cycle frequencies.

Effects of initial oxidation on β phase depletion and oxidation of CoNiCrAlY bond coatings fabricated by warm spray and HVOF processes

2013 ◽  
Vol 221 ◽  
pp. 59-69 ◽  
Author(s):  
Takeru Mori ◽  
Seiji Kuroda ◽  
Hideyuki Murakami ◽  
Hiroshi Katanoda ◽  
Yukihiro Sakamoto ◽  
...  
Keyword(s):  
Initial Oxidation ◽  
Warm Spray ◽  
Bond Coatings ◽  
Β Phase

scholarly journals Thermal Boundary Evolution of Molten Pool During Wire and Arc Additive Manufacturing of Single Walls of 5A06 Aluminum Alloy

Metals ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 848
Author(s):  
Haibin Geng ◽  
Jian Luo ◽  
Jinglong Li ◽  
Jianjun Gao ◽  
Xin Lin
Keyword(s):  
Thermal Conductivity ◽  
Temperature Gradient ◽  
Molten Pool ◽  
Thermal Evolution ◽  
Size Variation ◽  
Heating Time ◽  
Additive Manufacture ◽  
Cycle Frequency ◽  
Bottom Up ◽  
Surface Appearance

Molten pool uniformity is a prerequisite for wire and arc additive manufacture to achieve a uniform surface appearance. The thermal boundary is a key indicator to evaluate the thermodynamic state of the molten pool. This paper focuses on thermal analysis through finite element simulation and characterizes the thermal evolution of a molten pool during bottom-up deposition. The peak temperature of the substrate plate increases from 375.7 °C to 623.1 °C when peak current increases from 120 A to 180 A. The temperature gradient decreases from 40 °C/mm to 30 °C/mm. Weld speed increases from 0.15 m/min to 0.25 m/min; the temperature gradient is kept at about 30 °C/mm. Dimensionless thermal conductivity, Ge number, is proposed and defined as the criteria to estimate layer size variation. For Ip = 140 A, the average value of the Ge number is 87.7, and it shows the best numerical stability. Dimensionless thermal conductivity, Ge, is proposed and defined as the criteria to estimate the occurrence of layer size variation. Prolonging heating time and increasing cycle frequency, Ge number shows favorable stability during bottom-up deposition. The experimental results are consistent with analytical conclusions, which proves the validity of the Ge number as an indicator of deposition stability.

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