Microstructure of aluminide coatings on Ti6Al4V alloy produced by the slurry method with inorganic binder

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.

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Aluminide Protective Coatings Obtained by Slurry Method

Materials Science Forum ◽

10.4028/www.scientific.net/msf.782.590 ◽

2014 ◽

Vol 782 ◽

pp. 590-593 ◽

Cited By ~ 2

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.

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Structure of Intermetallic Al–Si Coating on Inconel 617

Materials Science Forum ◽

10.4028/www.scientific.net/msf.782.594 ◽

2014 ◽

Vol 782 ◽

pp. 594-597

Author(s):

Agnieszka Kochmańska ◽

Paweł Kochmański

Keyword(s):

Electron Microscopy ◽

Electron Backscatter Diffraction ◽

Nickel Superalloy ◽

Argon Atmosphere ◽

Aluminide Coatings ◽

Electron Backscatter ◽

Inconel 617 ◽

Slurry Method ◽

Backscatter Diffraction ◽

Scanning Electron

Nickel superalloy was coated by aluminide coatings by the slurry method. The slurry as active mixture containing aluminium and silicon powders, an activator and a binder. The coating were obtained by annealed in argon atmosphere. The structure of these coatings is two zonal and depends on time and temperature of producing. The phase composition was determined using following techniques: scanning electron microscopy (SEM) equipped with Xray microanalysis (EDS) combined with electron backscatter diffraction (EBSD) and Xray diffraction (XRD).

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Si-modified aluminide coatings deposited on Ti46Al7Nb alloy by slurry method

Intermetallics ◽

10.1016/j.intermet.2009.04.006 ◽

2009 ◽

Vol 17 (11) ◽

pp. 965-967 ◽

Cited By ~ 31

Author(s):

M. Goral ◽

L. Swadzba ◽

G. Moskal ◽

M. Hetmanczyk ◽

T. Tetsui

Keyword(s):

Aluminide Coatings ◽

Slurry Method

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The Influence of Silicon Amount on Structure of Si Modified Aluminide Coating Deposited on Ti46Al7Nb Alloy by Slurry Method

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.465.251 ◽

2011 ◽

Vol 465 ◽

pp. 251-254

Author(s):

Marek Goral ◽

Grzegorz Moskal ◽

Lucjan Swadźba ◽

Marek Hetmańczyk

Keyword(s):

Aluminide Coating ◽

Outer Zone ◽

Metal Powders ◽

Diffusion Treatment ◽

Aerospace Applications ◽

Aluminide Coatings ◽

Water Based ◽

Xrd Phase Analysis ◽

Slurry Method ◽

Si Content

The alloys based on the intermetallic phases from Ti-Al system are materials which, on the grounds of their resistance characteristics, could be widely used in automotive and aerospace applications. The insufficient oxidation resistance of this alloys could be increased by the coating silicon modification. The technology used in this investigation was the immersion in water-based slurry containing metal powders. MHI high-Nb (14 wt %) alloy has been used as the research material for the coatings produced. The water-based slurries containing Al and Si powders have been prepared with 0-80 wt % Si content. The diffusion treatment has been done at 950oC in 4h in the Ar atmosphere. The investigation has showed that the thickness of the coatings ranged from 30 to 40 m. The structure of the Si-modified aluminide coatings is as follows: (a) outer zone consisting of TiAl3 phase and titanium silicides, (b) middle zone consisting of columnar titanium silicides in phase TiAl3 matrix (c) the inner zone consisting of TiAl2 phase. The XRD phase analysis has confirmed Ti5Si3 creation and, in case of the high silicon content (above 20 wt %), also other silicides: types Ti5Si4,TiSi2,TiSi

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

Advances in Materials Science and Engineering ◽

10.1155/2018/5473079 ◽

2018 ◽

Vol 2018 ◽

pp. 1-12 ◽

Cited By ~ 1

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.

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