scholarly journals Microstructure of Al-Si Slurry Coatings on Austenitic High-Temperature Creep Resisting Cast Steel

2018 ◽  
Vol 2018 ◽  
pp. 1-12 ◽  
Author(s):  
Agnieszka E. Kochmańska
Keyword(s):  
High Temperature ◽  
Water Solution ◽  
Cast Steel ◽  
Single Step ◽  
High Temperature Creep ◽  
Technological Parameters ◽  
Inorganic Binder ◽  
X Ray ◽  
Temperature Creep ◽  
Aluminide Coatings

This paper presents the results of microstructural examinations on slurry aluminide coatings using scanning electron microscopy, X-ray microanalysis, and X-ray diffraction. Aluminide coatings were produced in air atmosphere on austenitic high-temperature creep resisting cast steel. The function of aluminide coatings is the protection of the equipment components against the high-temperature corrosion in a carburising atmosphere under thermal shock conditions. The obtained coatings had a multilayered structure composed of intermetallic compounds. The composition of newly developed slurry was powders of aluminium and silicon; NaCl, KCl, and NaF halide salts; and a water solution of a soluble glass as an inorganic binder. The application of the inorganic binder in the slurry allowed to produce the coatings in one single step without additional annealing at an intermediate temperature as it is when applied organic binder. The coatings were formed on both: the ground surface and on the raw cast surface. The main technological parameters were temperature (732–1068°C) and time of annealing (3.3–11.7 h) and the Al/Si ratio (4–14) in the slurry. The rotatable design was used to evaluate the effect of the production parameters on the coatings thickness. The correlation between the technological parameters and the coating structure was determined.

Aluminide coatings on Inconel 617 obtained by slurry method with inorganic binder

2017 ◽  
Vol 2 (85) ◽  
pp. 49-55 ◽  
Author(s):  
A.E. Kochmańska
Keyword(s):  
Cyclic Oxidation ◽  
Protective Coatings ◽  
Water Solution ◽  
Technological Parameters ◽  
Zone Structure ◽  
Inorganic Binder ◽  
Aluminide Coatings ◽  
Inconel 617 ◽  
Slurry Method ◽  
Slurry Composition

Purpose: The aim of this study was to manufacture and examine the structure of aluminide coatings formed on Ni-based super alloy Inconel 617 in an argon atmosphere. Design/methodology/approach: The coatings were produced by the slurry method at temperatures from 900 to 1100°C and times from 2 to 6 hours. The newly-developed slurry composition was: powders of aluminium and silicon; NaCl, KCl, NaF halide salts as an activator and a water solution of a soluble glass as an inorganic binder. The microstructure (SEM), chemical composition (EDS) and phase composition (XRD) of the coatings were determined. Additionally the correlation between the technological parameters and the coating thickness was analysed. Findings: Slurry aluminide coatings with newly-developed composition have been successfully produced. The obtained coatings had a multi-zone structure depending on manufacturing parameters. Research limitations/implications: The next stage of this research will be to determine the performance of the coatings under high temperature cyclic oxidation. Optimization of the production parameters will therefore be possible after oxidation and cyclic oxidation tests. Practical implications: The slurry method is economical due to low consumption of powder material. Another advantage of the applied slurry composition is the possibility of forming protective coatings on other substrates. Originality/value: The use of the inorganic binder in the slurry allowed to produce the coatings in one single step without additional annealing at an intermediate temperature as it is when applied organic binder. The grain size of aluminium and silicon powders was less than usually used. The applied activator dissolved the passive layers present on the surface both of the aluminum powder and of the nickel alloy and accelerated the reactions that occur during coating formation.

Aluminide Protective Coatings Obtained by Slurry Method

2014 ◽  
Vol 782 ◽  
pp. 590-593 ◽  
Author(s):  
Agnieszka Kochmańska ◽  
Paweł Kochmański
Keyword(s):  
Titanium Alloy ◽  
Nickel Alloy ◽  
Protective Coatings ◽  
Cast Steel ◽  
Technological Parameters ◽  
Inorganic Binder ◽  
Air Atmosphere ◽  
Aluminide Coatings ◽  
Slurry Method

The slurry aluminide coatings are produced on the three kind of substrates: hightemperature creep resistant cast steel, titanium alloy and nickel alloy. The slurry as active mixture containing aluminium and silicon powders, an activator and an inorganic binder. The coating were obtained by annealed in air atmosphere. The structure of these coatings is two zonal and depend on the type of substrate and technological parameters of producing.

scholarly journals Real-time study of transients during high-temperature creep of an Ni-base superalloy by far-field high-energy synchrotron X-ray diffraction

2018 ◽  
Vol 51 (5) ◽  
pp. 1274-1282 ◽  
Author(s):  
Roxane Tréhorel ◽  
Gabor Ribarik ◽  
Thomas Schenk ◽  
Alain Jacques
Keyword(s):  
High Temperature ◽  
Single Crystal ◽  
Real Time ◽  
Mechanical Response ◽  
High Energy ◽  
Diffraction Spot ◽  
Far Field ◽  
High Temperature Creep ◽  
X Ray ◽  
Temperature Creep

The high-temperature mechanical behavior of single-crystal Ni-base superalloys has been formerly studied by in situ triple-crystal synchrotron X-ray diffractometry (TCD). However, the 1/300 s recording frequency does not allow real-time tests. It is shown here that real-time monitoring is possible with far-field diffractometry in transmission. The use of a far-field camera enables one to follow a diffraction spot with high angular precision and high recording speed. This technique allows measurement of the mechanical response of an AM1 Ni-base single-crystal superalloy following steep load jumps and relaxations during high-temperature creep tests. Local crystal misorientation is revealed and rafting (oriented coalescence) is examined. This new technique is compared with TCD, in order to highlight its benefits and drawbacks.

scholarly journals On the Plastic Strain Accumulation in Notched Bars During High-Temperature Creep Dwell

2020 ◽  
Vol 36 (2) ◽  
pp. 167-176 ◽  
Author(s):  
Daniele Barbera ◽  
Haofeng Chen
Keyword(s):  
High Temperature ◽  
Cyclic Loading ◽  
Plastic Strain ◽  
Kinematic Hardening ◽  
High Temperature Creep ◽  
Strain Accumulation ◽  
Material Models ◽  
Cyclic Loading Condition ◽  
Hardening Material ◽  
Temperature Creep

ABSTRACTStructural integrity plays an important role in any industrial activity, due to its capability of assessing complex systems against sudden and unpredicted failures. The work here presented investigates an unexpected new mechanism occurring in structures subjected to monotonic and cyclic loading at high temperature creep condition. An unexpected accumulation of plastic strain is observed to occur, within the high-temperature creep dwell. This phenomenon has been observed during several full inelastic finite element analyses. In order to understand which parameters make possible such behaviour, an extensive numerical study has been undertaken on two different notched bars. The notched bar has been selected due to its capability of representing a multiaxial stress state, which is a practical situation in real components. Two numerical examples consisting of an axisymmetric v-notch bar and a semi-circular notched bar are considered, in order to investigate different notches severity. Two material models have been considered for the plastic response, which is modelled by both Elastic-Perfectly Plastic and Armstrong-Frederick kinematic hardening material models. The high-temperature creep behaviour is introduced using the time hardening law. To study the problem several results are presented, as the effect of the material model on the plastic strain accumulation, the effect of the notch severity and the mesh element type and sensitivity. All the findings further confirm that the phenomenon observed is not an artefact but a real mechanism, which needs to be considered when assessing off-design condition. Moreover, it might be extremely dangerous if the cyclic loading condition occurs at such a high loading level.

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