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

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

scholarly journals Microstructure of Aluminide Coatings Modified by Pt, Pd, Zr and Hf Formed in Low-Activity CVD Process

Coatings ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 421
Author(s):  
Marek Goral ◽  
Maciej Pytel ◽  
Kamil Ochal ◽  
Marcin Drajewicz ◽  
Tadeusz Kubaszek ◽  
...  
Keyword(s):  
Diffusion Zone ◽  
Aluminide Coating ◽  
Base Material ◽  
Outer Zone ◽  
Nickel Superalloy ◽  
Industrial Processes ◽  
Outward Diffusion ◽  
Near Surface ◽  
Aluminide Coatings ◽  
Low Activity

In the present article the doping of aluminide coatings by Pt/Pd as well as Hf or Pd using industrial processes was developed. The different combinations of doping elements were tested as well as their influence on chemical composition of coatings was initially investigated. The Pt and Pd and both Pt + Pd was electroplated on the surface of the MAR M247 nickel superalloy. The Zr or Hf was doped during low activity CVD aluminizing process using industrial Bernex BPX Pro 325S system. The conducted research showed that Pt and Pd formed the (Ni, Pd, Pt) Al solid solution in the outer additive layer. The higher concentration of palladium in the near surface and in the whole additive layer was detected. The platinum was presented below the surface of aluminide coating. The Zr or Hf was detected mainly in the diffusion zone. The low concentration of Zr (about 0.1 wt.%) in the outer zone was observed. The hafnium was detected mainly in the diffusion zone but in the outer additive layer a small concentration of this element was measured. The obtained results showed that formation of three elements (Pd, Pt) + Zr or Hf modified aluminide coating using proposed technology is possible. The structure of all obtained aluminide coatings was typical for a low-activity, high temperature (LAHT) formation process mainly by outward diffusion of Ni from base material.

Hafnium Modified Aluminide Coatings Obtained by the CVD and PVD Methods

2015 ◽  
Vol 227 ◽  
pp. 353-356 ◽  
Author(s):  
Maryana Zagula-Yavorska ◽  
Jolanta Romanowska ◽  
Jan Sieniawski ◽  
Małgorzata Wierzbińska
Keyword(s):  
Volume Fraction ◽  
Aluminide Coating ◽  
Intermetallic Phase ◽  
Double Layers ◽  
Middle Zone ◽  
Nickel Substrate ◽  
Diffusion Treatment ◽  
Cvd Method ◽  
Aluminide Coatings ◽  
Nial Phase

Zirconium, hafnium or platinum modification of NiAl phase increases the oxidation resistance of diffusion aluminide coatings. Small hafnium addition to aluminide coatings decreases the oxidation rate of nickel superalloys at 1100 °C.The paper presents comparison of structures of hafnium modified aluminide coatings deposited in two different ways on pure nickel. In the first way double layers of hafnium 3 μm thick and aluminum 3 μm thick were deposited by the EB-PVD on the nickel substrate. The double layers were subjected to diffusion treatment at 1050 °C for 6 h and 20 h. In the second method, a hafnium layer was deposited by the EB-PVD method, whereas aluminum was deposited by the CVD method. The obtained coatings were examined by the use of an optical microscope (microstructure and coating thickness) and a scanning electron microscope (chemical composition on the cross-section of the modified aluminide coating). Microstructures and phase compositions of coatings obtained by different methods differ significantly. Diffusion treatment for 6 h leads into formation of the Ni5Hf phase. The elongation of the diffusion time from 6 to 20 h decrease the volume fraction of the Ni5Hf phase. An aluminide coating deposited by the CVD method at 1050 °C at the nickel substrate with prior hafnium layer (3 μm thick) has a triple zone structure. An outer zone consists of the NiAl phase, a middle zone consists of the Ni3Al phase, and the Ni(Al) phase forms an inner zone, close to the substrate. An NiHf intermetallic phase is between the outer and the middle zone, whereas Ni3Hf is between the inner zone and the substrate.

Cyclic-Oxidation of RexOy-Modified Aluminide Coating

2012 ◽  
Vol 557-559 ◽  
pp. 1721-1726
Author(s):  
Yong Dong Wang ◽  
Yue Bo Zhou
Keyword(s):  
Composite Film ◽  
Cyclic Oxidation ◽  
Aluminide Coating ◽  
Pack Cementation ◽  
Reactive Element ◽  
Aluminide Coatings ◽  
Oxidation In Air

Reactive reactive element oxide RexOy (Re=Ce, Y)-modified aluminide coatings were developed by aluminizing the as-codeposited Ni-RexOy composite film using pack cementation method at 1100°C for 4 h. By comparison, aluminizing was also performed with the same condition on an as-deposited Ni film without RexOy particles. SEM/EDAX and TEM results indicated that the co-deposited CeO2 or Y2O3 particls were homogeneously dispersed in the finer-grain nanocrystalline Ni grains. The cyclic oxidation in air at 900°C indicated that the RexOy -modified aluminide coatings were profoundly spallation resistance as compared to the RexOy -free coatings due to the formation of a continuous adherent α-Al2O3 scale.

The Influence of Long-Term Heat Treatment on Microstructure of Zr-Modified Aluminide Coating Deposited by CVD Method on MAR M200+Hf Nickel Superalloy

2013 ◽  
Vol 592-593 ◽  
pp. 469-472 ◽  
Author(s):  
Ryszard Filip ◽  
Marek Góral ◽  
Marcin Zawadzki ◽  
Andrzej Nowotnik ◽  
Maciej Pytel
Keyword(s):  
Heat Treatment ◽  
Aluminide Coating ◽  
Chemical Vapour ◽  
Nickel Superalloy ◽  
Phase Changes ◽  
Vacuum Furnace ◽  
Aluminide Coatings ◽  
Nial Phase ◽  
Main Component

The article presents the investigation of influence of long-term annealing of Zr modified aluminide coatings on its microstructure. The coatings were deposited by Chemical Vapour Deposition on MAR M200+Hf nickel superalloy. Annealing was carried out in a vacuum furnace at the temperature 1020°C within the period of 12, 16 and 20 hours respectively. The microstructral analysis was carried out using Hitachi S-3400 scanning electron microscope. Phase changes in the aluminide layer were observed, particularly the NiAl phase into Ni3Al. Changes in thickness of individual layers in the coating were observed. Conducted research showed that there is no influence of Zr on structure of the aluminide coating during annealing. The structure changes are similar to observed in simple aluminide coating. The maximum time of heat treatment without significant influence on structure of aluminide coating is 16 hours. After that time the main component of coating is NiAl phase.

Effect of Hf Addition on High Temperature Properties of Ir-Containing Alloy Coatings

2007 ◽  
Vol 546-549 ◽  
pp. 1689-1694 ◽  
Author(s):  
Hideyuki Murakami ◽  
K. Kamiya ◽  
Akihiro Yamaguchi ◽  
Ying Na Wu ◽  
Seiji Kuroda
Keyword(s):  
High Temperature ◽  
Cyclic Oxidation ◽  
Flat Surface ◽  
Small Difference ◽  
Aluminide Coating ◽  
High Temperature Properties ◽  
Aluminide Coatings ◽  
Cyclic Oxidation Test ◽  
Hf Addition ◽  
Pack Cementation Process

In the present study, high temperature properties of Ir-modified and Ir-Hf-modified aluminide coatings on Ni-based single crystal superalloy TMS-82+ were discussed. They were prepared by depositing pure Ir and Ir-Hf alloys on TMS-82+ using magnetron sputtering and EB-PVD, followed by a conventional Al-pack cementation process. The effects of Hf addition on the oxidation resistance and top-coat spallation resistance were investigated. Cyclic oxidation test at 1423K for 1h as one heating cycle revealed that while there is a small difference in oxidation kinetics and spallation lives between Ir and Ir-Hf coatings, drastic difference in surface morphology was observed. After 50 oxidation cycles the Ir-modified aluminide coating showed surface rumpling whereas the Ir-Hf modified aluminide coatings kept the flat surface. It was also revealed that excessive addition of Hf promoted the internal oxidation, resulting in the deterioration of substrates. These results agree with the conventional Pt-modified aluminide coatings and Ni-Al-Hf alloys.

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.

Microstructure Investigation of Aluminide Coatings after Platinum Modification Deposited by CVD Method on Inconel 713 LC Ni-Base Superalloy

2011 ◽  
Vol 409 ◽  
pp. 883-888
Author(s):  
M. Yavorska ◽  
Jan Sieniawski ◽  
Ryszard Filip ◽  
Tadeusz Gancarczyk
Keyword(s):  
Diffusion Coating ◽  
Diffusion Treatment ◽  
Cvd Method ◽  
Aluminide Coatings ◽  
Heat Treated ◽  
Two Phases ◽  
Electroplating Process ◽  
Low Activity ◽  
Platinum Electroplating ◽  
Base Superalloy

In the present study, microstructure investigation of aluminide coatings after platinum modification deposited by CVD method on Inconel 713 LC Ni-base superalloys were performed. The platinum coatings 3 and 7 m thick were deposited by electroplating process. The diffusion treatment of platinum electroplating coatings at the temperature 1050 °C was carried out for 2h. The low-activity CVD aluminizing of heat treated coatings at the temperature 1050 °C was conducted for 8 h. On the grounds of the obtained results it was found that microstructure of diffusion treated platinum electroplating coatings 3 m and 7 m thick consisted of two phases: γ-Ni and (Al0.25Pt0.75)Ni3. The low activity CVD aluminizing of diffusion treated platinum electroplating coatings 3 and 7 m thick enables the diffusion coating obtaining. The main constituent of aluminide coatings was (Ni,Pt)Al phase.

Vapor-Phase Slurry Aluminide Coating for Gas Turbine Components

2005 ◽  
Author(s):  
Jeffrey J. McConnell ◽  
Thomas A. Kircher ◽  
Bruce G. McMordie
Keyword(s):  
Gas Turbine ◽  
Vapor Phase ◽  
Aluminide Coating ◽  
Thermal Mass ◽  
Nickel Steel ◽  
Phase Reaction ◽  
Aluminide Coatings ◽  
Attractive Option ◽  
Oxidation And Corrosion ◽  
Liquid Phase Reaction

Diffusion aluminide coatings have long been used to protect gas turbine components made of nickel, steel, and cobalt alloys from oxidation and corrosion at high temperatures. The most common method for producing aluminide coatings is to “pack” parts within a powdered mixture of aluminum metal, halide compounds and inert oxide. When this mixture is heated, the halide reacts with the aluminum to form aluminum-rich vapor that migrates to the part and forms protective intermetallic aluminide layers. Similar aluminide coatings can be produced from “vapor-phase” slurries that incorporate aluminum pigments and halide activators. Unlike slurries long used to locally repair pack aluminides via a liquid-phase reaction with molten (or semi-molten) aluminum, the thickness of an aluminide formed from a vapor-phase slurry depends primarily upon the diffusion cycle used, not upon the amount of slurry applied to the surface. By eliminating the need for a powder pack, the vapor-phase slurry reduces thermal mass of the furnace load, increases batch flexibility and simplifies masking. Examples of aluminide coatings that may be produced by this method are presented. It is also shown that the oxidation resistance of an aluminide produced from a vapor-phase slurry is comparable to that of a coating of similar composition formed by pack aluminization. Consequently, the properties and advantages of vapor-phase slurry aluminization make this method an attractive option for coating the entire gas path surfaces of many components.

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