scholarly journals Microstructural Evolution and Mechanical Evaluation of a Laser-Induced Composite Coating on a Ni-Based Superalloy during Thermal Exposure

Materials ◽  
2019 ◽  
Vol 12 (9) ◽  
pp. 1439
Author(s):  
Yuebing Li ◽  
Yanming He ◽  
Chuanyang Lu ◽  
Wenjian Zheng ◽  
Jianguo Yang ◽  
...  
Keyword(s):  
Microstructural Evolution ◽  
Mechanical Performance ◽  
Volume Fraction ◽  
Thermal Exposure ◽  
Eutectic Structure ◽  
Laser Surface ◽  
Microstructural Stability ◽  
Coating Materials ◽  
Before And After ◽  
Surface Modified

A Ni–17Mo–7Cr-based superalloy was laser surface-modified to improve its tribological properties. Si particles were employed as coating materials. Si melted on the surface of the alloy during the process, triggering the formation of Mo6Ni6C carbides and Ni–Si intermetallics. A defect-free coating obtained was mostly made up of primary Mo6Ni6C and γ-Ni31Si12, as well as a eutectic structure of β1-Ni3Si and α-Ni-based solid solution (α-Ni (s.s)). The volume fraction of hard reinforcements (Mo6Ni6C, γ-Ni31Si12, and β1-Ni3Si) reached up to 85% in the coating. High-temperature microstructural stability of the coating was investigated by aging the coating at 1073 K for 240–480 h, to reveal its microstructural evolution. In addition, the mechanical performance of the coating was investigated. The nanoscale elastic modulus and hardness of Mo6Ni6C, γ-Ni31Si12, and α-Ni (s.s) were characterized using the nanoindentation tests. The nanoscratch tests were performed to measure the local wear resistance of the coating. Lastly, the Vickers hardness distribution across the cross-section of the coating before and after thermal exposure was compared. The work performed provides basic information understanding the microstructural evolution and mechanical performance of laser-induced coatings on Ni-based superalloys.

MICROSTRUCTURAL EVOLUTION AND RESIDUAL STRESSES OF AIR-PLASMA SPRAYED THERMAL BARRIER COATINGS UNDER THERMAL EXPOSURE

2010 ◽  
Vol 17 (03) ◽  
pp. 337-343 ◽  
Author(s):  
JAE-YOUNG KWON ◽  
JAE-HYOUN KIM ◽  
SANG-YEOP LEE ◽  
YEON-GIL JUNG ◽  
HYUN CHO ◽  
...  
Keyword(s):  
Thermal Barrier Coatings ◽  
Microstructural Evolution ◽  
Thermal Exposure ◽  
Thermally Grown Oxide ◽  
Thermal Barrier ◽  
Air Plasma ◽  
Barrier Coatings ◽  
Before And After ◽  
Peak Areas ◽  
Plasma Sprayed

Microstructural evolution and fracture behavior of zirconia ( ZrO2 )-based thermal barrier coatings (TBCs) were investigated under thermal exposure. New ZrO 2 granule with 8 wt.% yttria ( Y2O3 ) with a deformed hollow morphology was developed through a spray drying process and employed to prepare TBCs. The thermal exposure tests were conducted at 1210°C with a dwell time of 100 h till 800 h. The residual stress at the interface between top coat and thermally grown oxide (TGO) layer was measured using a nanoindentation technique before and after thermal exposure. Vertical cracks on the top coat were newly formed and interlamellar cracks at the interface were enhanced after the thermal exposure of 800 h. Especially, partial delamination was observed at the interface after the thermal exposure of 800 h in TBC samples tested. The microstructural evolution in the top coat could be defined through load–displacement curves, showing a higher load or a less displacement after the thermal exposure of 800 h. The stress state was strongly dependent on the TGO geometry, resulting in the compressive stresses at the "valleys" or the "troughs," and the tensile stresses at the "crests" or peak areas, in the ranges of -500 to -75 MPa and of +168 to + 24 MPa, respectively. These stress terms incorporated with resintering during thermal exposure affected the mechanical properties such as hardness and elastic modulus of the top coat.

Effects of Ruthenium on Microstructure and Stress Rupture Properties of a Nickel-Base Single Crystal Superalloy

2013 ◽  
Vol 747-748 ◽  
pp. 777-782
Author(s):  
Shuai Yang ◽  
Jian Zhang ◽  
Yu Shi Luo ◽  
Yun Song Zhao ◽  
Ding Zhong Tang ◽  
...  
Keyword(s):  
Volume Fraction ◽  
Stress Rupture ◽  
Thermal Exposure ◽  
Microstructural Stability ◽  
Stress Rupture Properties ◽  
Tcp Phases ◽  
Mean Size ◽  
Nickel Base ◽  
Rupture Properties

The effect of Ru addition (0 wt.%, 3 wt.%, 5 wt.%), on γ morphology, elemental segregation, microstructural stability under long-term thermal exposure at 980 and stress rupture properties at 1100°C/130MPa have been studied. The results showed that with the increase of Ru content, the γ/γ eutectic volume fraction and the dendrite arm spacing decreased gradually. The γ' phase mean size in three alloys decreased with the increase of the Ru content. On the other hand, the dendrite segregation of Al, Ta towards interdendrite area and ReW towards dendrite core area was alleviated gradually with the increase of the Ru content. The increase of Ru content from 0 wt.% to 5 wt.% pronouncedly enhanced the stress rupture properties by suppressing the precipitation of TCP phases effectively at high temperature.

Role of Cobalt in the Microstructural Stability of Single Crystal Superalloys

2016 ◽  
Vol 849 ◽  
pp. 557-562 ◽  
Author(s):  
Jing Yang Chen ◽  
Qing Li ◽  
Jie Li ◽  
Xin Tang ◽  
Cheng Bo Xiao
Keyword(s):  
Single Crystal ◽  
Volume Fraction ◽  
Thermal Exposure ◽  
Precipitate Size ◽  
Microstructural Stability ◽  
Tcp Phases ◽  
The Stability ◽  
Co Addition ◽  
Good Agreement

The effects of Co additions on the evolution of γ' precipitates and topologically close-packed (TCP) phases during thermal exposure at 950 °C were investigated for two Ni-based single crystal superalloys with 7.9 wt.% Co and 9.1 wt.% Co. The results indicated that the γ′ morphology was not affected by Co content, whereas γ′ volume fraction decreased and precipitate size increased due to lower Co addition after standard heat treatment. The coarsening of γ′ precipitates in both alloys was controlled by diffusion. The γ′ coarsening rate increased, while the stability of γ′ volume fraction decreased due to lower level of Co addition during 950 °C thermal exposure because more Co addition suppressed the diffusion process. High Co addition promoted the formation of μ phase after thermal exposure at 950 °C for 1000 h due to higher γ′ volume fraction, more stable γ′ volume fraction and higher electron vacancy number. The experimental results of μ phase precipitation showed good agreement with thermodynamic calculation by JMatPro.

Microstructural characterization of a rapidly solidified Al-Fe-V-Si alloy for elevated temperature applications

1988 ◽  
Vol 46 ◽  
pp. 550-551
Author(s):  
R. E. Franck ◽  
J. A. Hawk ◽  
G. J. Shiflet
Keyword(s):  
High Temperature ◽  
Elevated Temperature ◽  
Grain Growth ◽  
Volume Fraction ◽  
Microstructural Characterization ◽  
Second Phase ◽  
Microstructural Stability ◽  
Elevated Temperature Strength ◽  
Temperature Applications

Rapid solidification processing (RSP) is one method of producing high strength aluminum alloys for elevated temperature applications. Allied-Signal, Inc. has produced an Al-12.4 Fe-1.2 V-2.3 Si (composition in wt pct) alloy which possesses good microstructural stability up to 425°C. This alloy contains a high volume fraction (37 v/o) of fine nearly spherical, α-Al12(Fe, V)3Si dispersoids. The improved elevated temperature strength and stability of this alloy is due to the slower dispersoid coarsening rate of the silicide particles. Additionally, the high v/o of second phase particles should inhibit recrystallization and grain growth, and thus reduce any loss in strength due to long term, high temperature annealing.The focus of this research is to investigate microstructural changes induced by long term, high temperature static annealing heat-treatments. Annealing treatments for up to 1000 hours were carried out on this alloy at 500°C, 550°C and 600°C. Particle coarsening and/or recrystallization and grain growth would be accelerated in these temperature regimes.

Sunlight exposure: the effects on the performance of paragliding fabric

2018 ◽  
Vol 69 (05) ◽  
pp. 381-389
Author(s):  
MENGÜÇ GAMZE SÜPÜREN ◽  
TEMEL EMRAH ◽  
BOZDOĞAN FARUK
Keyword(s):  
Mechanical Properties ◽  
Aging Process ◽  
Air Permeability ◽  
Sunlight Exposure ◽  
Test Results ◽  
Coating Materials ◽  
Strength Tests ◽  
Before And After ◽  
The Relationship ◽  
Dark Blue

This study was designed to explore the relationship between sunlight exposure and the mechanical properties of paragliding fabrics which have different colors, densities, yarn counts, and coating materials. This study exposed 5 different colors of paragliding fabrics (red, turquoise, dark blue, orange, and white) to intense sunlight for 150 hours during the summer from 9:00 a.m. to 3:00 p.m. for 5 days a week for 5 weeks. Before and after the UV radiation aging process, the air permeability, tensile strength, tear strength, and bursting strength tests were performed. Test results were also evaluated using statistical methods. According to the results, the fading of the turquoise fabric was found to be the highest among the studied fabrics. It was determined that there is a significant decrease in the mechanical properties of the fabrics after sunlight exposure. After aging, the fabrics become considerably weaker in the case of mechanical properties due to the degradation in both the dyestuff and macromolecular structure of the fiber

scholarly journals Photocatalytic Degradation of Malachite Green Dye from Aqueous Solution Using Environmentally Compatible Ag/ZnO Polymeric Nanofibers

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2033
Author(s):  
Marwa F. Elkady ◽  
Hassan Shokry Hassan
Keyword(s):  
Photocatalytic Degradation ◽  
Malachite Green ◽  
Degradation Efficiency ◽  
Solution Flow Rate ◽  
Gravimetric Analysis ◽  
Electrospinning Technique ◽  
Malachite Green Dye ◽  
Polymeric Nanofibers ◽  
Before And After ◽  
Surface Modified

An efficient, environmentally compatible and highly porous, silver surface-modified photocatalytic zinc oxide/cellulose acetate/ polypyrrole ZnO/CA/Ppy hybrid nanofibers matrix was fabricated using an electrospinning technique. Electrospinning parameters such as solution flow rate, applied voltage and the distance between needles to collector were optimized. The optimum homogenous and uniform ZnO/CA/Ppy polymeric composite nanofiber was fabricated through the dispersion of 0.05% wt ZnO into the dissolved hybrid polymeric solution with an average nanofiber diameter ranged between 125 and 170 nm. The fabricated ZnO-polymeric nanofiber was further surface-immobilized with silver nanoparticles to enhance its photocatalytic activity through the reduction of the nanofiber bandgap. A comparative study between ZnO polymeric nanofiber before and after silver immobilization was investigated using X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and thermal gravimetric analysis (TGA). The photocatalytic degradation efficiency of the two different prepared nanofibers before and after nanosilver immobilization for malachite green (MG) dye was compared against various experimental parameters. The optimum degradation efficiency of nanosilver surface-modified ZnO-polymeric nanofibers was recorded as 93.5% for malachite green dye after 1 h compared with 63% for ZnO-polymeric nanofibers.

scholarly journals Nanocomposites Materials of PLA Reinforced with Nanoclays Using a Masterbatch Technology: A Study of the Mechanical Performance and Its Sustainability

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2133
Author(s):  
Helena Oliver-Ortega ◽  
Josep Tresserras ◽  
Fernando Julian ◽  
Manel Alcalà ◽  
Alba Bala ◽  
...  
Keyword(s):  
Food Packaging ◽  
Mechanical Performance ◽  
Polymeric Materials ◽  
Barrier Properties ◽  
Food Tray ◽  
Environmental Concerns ◽  
Poly Lactic Acid ◽  
The Matrix ◽  
Surface Modified ◽  
Being Moved

Packaging consumes around 40% of the total plastic production. One of the most important fields with high requirements is food packaging. Food packaging products have been commonly produced with petrol polymers, but due to environmental concerns, the market is being moved to biopolymers. Poly (lactic acid) (PLA) is the most promising biopolymer, as it is bio-based and biodegradable, and it is well established in the market. Nonetheless, its barrier properties need to be enhanced to be competitive with other polymers such as polyethylene terephthalate (PET). Nanoclays improve the barrier properties of polymeric materials if correct dispersion and exfoliation are obtained. Thus, it marks a milestone to obtain an appropriate dispersion. A predispersed methodology is proposed as a compounding process to improve the dispersion of these composites instead of common melt procedures. Afterwards, the effect of the polarity of the matrix was analyzing using polar and surface modified nanoclays with contents ranging from 2 to 8% w/w. The results showed the suitability of the predispersed and concentrated compound, technically named masterbatch, to obtain intercalated structures and the higher dispersion of polar nanoclays. Finally, the mechanical performance and sustainability of the prepared materials were simulated in a food tray, showing the best assessment of these materials and their lower fingerprint.

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