Thermal Cycle Behavior of the Interface of AG3/75E/55E and AU4G/75E/55E Multimaterials Elaborated by Thermal Spray

doi:10.21203/rs.3.rs-4067999/v1

This study aims at the elaboration of two aluminum alloys based multimaterials (AG3/75E / 55E, AU4G/75E/55E); using the thermal projection technique. Thermanit stainless steel (55E) was deposited on two aluminum alloys: AG3 (5754) and AU4G (2017A) which are commonly used in the aeronautical industry; a Ni-Al bond coat (75E) was deposited between the coatings and the substrates to avoid the unwanted effect of aluminum oxide on the two substrates which acts as a diffusion barrier and therefore penalizes bonding.

A thermal fatigue device was also used in order to study physico-chemical and mechanical behavior of the interface under application of thermal shocks and post treatment.

The results show a better better resistance to cycles thermal in the case of composite AU4G/75E/55E was noted.

aluminum alloys

thermal projection

multimaterial

thermal fatigue

adhesion

Since the sixties, the need for economy of both energy and materials have led various industries particularly the aeronautical, naval and automobile industries to make significant steps towards the development of novel materials with enhanced mechanical, thermal and electrochemical properties as well as new techniques of assembly. This led to the development of new aluminum, magnesium and titanium alloys which are among the most needed by the world market. These materials have low density, reasonable mechanical properties and high resistance to corrosion [1].

Nevertheless, problems arising at high temperatures such as thermal fatigue [2;3] are a major drawback for these alloys which led the researchers to look out for smart solutions to improve the performance of mechanical parts and devices and to meet the needs of more and more demanding customers; one of the most effective solutions protect this alloys from high temperature is the thermal spray coating [4] ; it is a surface treatment used in various industries [5-11] aimed at improving material properties such as thermal properties; wear resistance and friction [12].

Several researchers used this technique to improve the properties of surfaces; Sadki and al [13;14] produce stainless thermanite coatings onto substrates on aluminum alloys using arc spray process (ASP); their results showed a large changes in mechanical properties of aluminum alloy after coating due to the large difference on microstructure and the microhardness of coatings is nearly four times that of the two substrates of aluminum alloys. Mohankumar and al 2022 ; Patel and al 2022 [15] elaborate Cr3C2-NiCr coating and nickel aluminium bronze (NAB) by HVOF spray ; the caotings were tested in 3.5 wt.% NaCl solution with different Na2S concentrations, theirs results show the Cr3C2-NiCr coating exhibited more stable corrosion resistance in the NaCl solution.

Until now the thermal fatigue of coatings sprayed by electric arc wire spray has not been fully investigated.

The aim of this study is to evaluate the thermal fatigue on interface adhesion of the metal/metal multimaterials by physico-chemical and mechanical characteriazation under application of thermal shocks and post treatment. The results show a better behavior after the heating treatment in the case of composite AU4G/75E/55E was also noted.

2.1- Coating and substrate materials

Two different types of substrate-based aluminum alloys with different chemical compositions were used. The first one is AU4G (2017A); the second is AG3 (5457); they were provided by the Aerospace Equipment Retrofit Unit (ERMA); Algiers; Algeria. The chemical composition of substrates was determined by using analysis X-rays fluorescence as is given in table 1.

Table 1. Chemical composition of substrates

Alloys	Al %	Cu %	Si %	Mn %	Cr %	Mg %
AU4G (2017A)	94.3	4	0.5	0.5	-	0.7
AG3 (5457)	96.3	-	-	0.3	0.3	3.1

The specimens are made starting from a cylindrical rod of 25mm diameter, which is sliced in the form of discs of 5 mm of thickness (Fig.1).

Before thermal spray process We have used the surface preparation technique known as stripping; the two substrates AU4G and AG3 are coated electrolytically with a layer of zinc and bombarded with a jet of metal particles in order to obtain a surface ready to receive the deposit and to ensure a good adhesion. The obtained Ra ~0.09 μm and Ra ~3.33μm were measured by an optical profilemeter (Alti-Surf) and each Ra value was averaged from three measurements. For materials with low adhesion, the use of under tack coat is of paramount importance for improving the adhesion of the coating on the substrate. In our case, a sub-adhesion layer of about 0.1 mm thickness was produced by depositing a 75 E grade Ni-Al alloy. We have used Thermanit 55 E as the coating material which is a refractory stainless steel used as a thermal barrier and which is moreover wear, friction and corrosion resistant. The chemical composition of Bond coat and Coating is given in table 2 below:

Table 2. chemical composition of Bond coat and Coating

Elements	Fe %	Cr%	Mn%	Ni%	C%	Al%
Bond coat (75 E)	-	-	-	79.2	-	19.4
Coating (55E)	66.6	18.5	8.1	5.5	0.132	-

This composition corresponds to the grade of stainless steel: X12 CrMnNi 18-8-5.

2.2 Thermal spray techniques

We have deposited Thermanit 55 E stainless steel on two different aluminum alloys AG3 and AU4G using Arc wire thermal spray process (EN10025; fig 2). The projection parameters values given by the manufacturer (data sheet) are summarized in table 3.

In order to achieve the best results as regards the amalgamation of the jet with the base metal, one should make sure that the projection parameters meet the recommended values given by the manufacturer (data sheet), and which are summarized in table 3:

Table 3. The projection parameters.

Air pressure in the engine	3.8 bars
Air pressure in the spray nozzle	3 bars
Feed rate of wire	0.064 m/s
Generator voltage	30 V
Amperage	100 A
Projection Distance	140 mm
Firing angle	90 °

The spray gun, a Thermo Spray-234 (Fig.3), is a handheld device with a remarkable design that makes it both flexible and easy to manipulate. This device uses an electric arc between two consumable metal wires fed into the gun. A jet of compressed air sprays the molten metal and projects it onto the substrate.

The final form of our samples after thermal spray is presented in Figure 4.

2.3 Thermal fatigue

The Composite thus obtained are subjected to the treatment of thermal fatigue (fig 5) cycles of heating and cooling; The heating period up to 450°C is reached after 300s, and after cooling close to 600s, the sample reaches a temperature of 35°C; The cycle numbers are: 0; 75; 100; 215. We subsequently carried out the different analysis techniques to assess the effect of fatigue on the adhesion and properties of the coating.

2.4 Ultrasonic Non Destructive Test

We used the technique of immersion testing with the method of transmission in order to assess the adhesion of the samples after a given number of cycles.

2.5. Micro Structural Characterization

Microstructures of coatings were observed on scanning electron microscope (SEM) of QUANTA coupled with energy dispersive X-ray analyzer, which allows a correspondence of image observation and chemical analysis. The coating thickness was measured by taking back scattered electron image (BSEI). The beam size is typically on the order of 1μm, and a typical detection limit is ≤ 1 at %, and thus, we anticipated that this method might provide information on the extent of homogenization achieved during the thermal spraying.

2.6 Vickers microhardness

We used Shimadezu HMV-M3, The test force is applied with an indenter of diamond quadrangular pyramid with a facing angle of 136 °at the top under a light load and a metallographic microscope. A load of 100 gf was applied to the surface perpendicular to the substrate and the coating for 10 seconds, without shock or vibration.

2.7 Post treatment

We studied the influence of post-treatment on the quality of the coating; heat treatment was carried out (400°C) to the two composites projeted with different treatment times (15 min, 4 hours and 24 hours).

3.1- ULTRASONIC NON DESTRUCTIVE TEST

Adhesion in thermal projection is generated essentially by three types of connections [16]: mechanical attachment, connections chemicals and metallic bonds. Given the rapid solidification of particles and of the layered microstructure of deposits, mechanical fixation is the main mechanism adhesion. The mechanical properties of the deposit, in particular its adhesion/cohesion, depend on the morphology of the flakes, the effective contact surface between flakes and the roughness of the substrate [17]. Therefore, the preparation of the substrate before projection conditions largely the final adhesion of the deposit. Thus, good sandblasting (injection of particles, control of the compressive stresses generated in the vicinity of the surface and any preheating conditions of the substrate) will promote the mechanical attachment of the particles. Of the cleaning and degreasing operations of the substrate and the elimination of sandblasting residues promote good contact between the coating layer and the substrate

Figures 6 and 7 represent the ultrasonic signal amplitudes as a function of time which vary from one sample to another depending on the number of thermal cycles carried out, this means that there is a portion of ultrasonic energy stopped and , as a result, the energy reaching the receiver is reduced, there is a fault intercepting the signal. From these amplitudes diagrams (fig 6 and 7), we can clearly see that we have a good adhesion in both multimaterials.

From figure 8, depicting the evolution of the attenuation coefficient as a function of thermal cycles number, we see an increase of this parameter for both multimaterials. This result may be due to the presence of flaws in the studied parts. This may result of cracks or decrease in adhesion at the interface between the coating and the substrate

3.2 Micro Structural Characterization

the microstructure of the coatings obtained by thermal spraying depends on the method used, the spraying parameters (speed, chemical composition, temperature, melt, size) and the characteristics of the projected material (roughness, temperature, physico-chemical properties) [18-24]. The final properties of these deposits are strongly affected by the presence of defects which correspond to partially melted particles or unmelted containing oxides, cracks, porosities, as well as stresses residual.

The observation of a cross-section shows the appearance of the different layers of the two elaborated multimaterials.

A good adhesion was achieved between the substrate and the coating in both composites (before 75 thermal cycles and 100 cycles for AG3/75E/55E and AU4G/75E/55E respectively).
This adhesion is probably due to the scouring treatment and to the presence of the adhesion layer projected that acts as a binder for Thermanit (final protective coating) on the substrate.
After 75 thermal cycles and 100 cycles for AG3/75E/55E AU4G/75E/55E, observation of interfaces showed the existence of defects at the interfaces which constitute the initiation of rupture.This decohesion is the result of the accumulation of thermal stresses formed during the various applied cycles. It is known that the thermal properties (coefficient of thermal expansion, etc.) of different materials may significantly affect their behavior.
After 100 cycles and 215 cycles for composites AG3/75E/55E and AU4G/75E/55E respectively, cracks at the interface are larger and propagate in a more pronounced way.

3.2 Microhardness of multimaterials AG3/75E/55E and AU4G/75E/55E

Figures 10 show the evolution of the microhardness of the two multimaterials according to the depth.

For 0 thermal cycles
For areas close to the deposit, there is a microhardness greater than that of the substrate in the case of two composites. Thus, the deposit obtained by thermal spraying has improved the mechanical properties at the surface of our materials.

After 100 and 215 thermal cycles

There is a stability of the microhardness for alloy AG3 and a decrease of the microhardness in the case of the alloy AU4G as the number of thermal cycles increases. This was due possibly to an increase of the grain size.

At the surface, there is an increase of microhardness for both multi- AU4G/75E/55E and AG3/75E/55E. This hardening may be caused by the densification of the coating.

3.4- POST-TREATMENT

As can be seen from figure 11, duration of heating treatment has a marked influence on crack propagation along the interface. We notice that the cracks at the interfaces increase as a function of time; these are more important in the case of the composite based on

In this study, two different aluminium alloys based composites were elaborated using the thermal projection technique. Different characterization methods of investigation (both destructive and non destructive) were used in order to the quality of the interface between coating and substrate. Results reveal the following main points:

A good bonding AU4G/75E/55E and AG3/75E/55E was noted.
The ultrasonic tests have shown that the higher the number of thermal cycles applied, the higher the attenuation coefficient, leading to increased defects.
The micrographic examination of the various interfaces in cross-sections of the surface of the coating shows a lamellar structure of the deposit.
The increase in crackings with the number of thermal cycles is noted in the case of the two multimaterials (AU4G/75E/55E and AG3/75E/55E).
Measurements of the microhardness confirmed the improvement of mechanical properties of the surface of our material. Also, an increase in the microhardness of the coating according to the number of cycles is probably due to the presence of type Cr3C2 carbides and oxides NiO and MnO projection.
The appearance of cracks (after post-treatment) in the case of composite AU4G/75E/55E and their propagation in the case of AG3/75E/55E is mainly due to the difference of thermal properties (coefficient of thermal expansion, conductivity thermal,) of the various constituents of the elaborated composites. A better behaviour after the heating treatment in the case of composite AU4G/75E/55E was also noted.

Aknowlegdements

The authors wish to thank the Etablissement de Rénovation du Matériel Aéronautique (ERMA) for providing all the materials used in this study.

Author Contribution

[1] A. Lakshmikanthan ; S. Angadi ; V. Malik ; K. Kuldeep; Saxena ; « Mechanical and Tribological Properties of Aluminum-Based Metal-Matrix Composites” ; September 2022 ; Materials ; DOI:10.3390/ma15176111[2] L. Milosan ; T. Bedő ; C. Gabor ; D. Munteanu ; M. Pop ; D. Catana ; M. Cosnita ; B. Varga ; Characterization of Aluminum Alloy–Silicon Carbide Functionally Graded Materials Developed by Centrifugal Casting Process ; Appl. Sci. 2021, 11(4), 1625; https://doi.org/10.3390/app11041625[3] H. Arami, R. Khalifehzadeh , M. Akbari, F. Khomamizadeh ; Microporosity control and thermal-fatigue resistance of A319 aluminum foundry alloy ; Materials Science and Engineering: A ; Volume 472, Issues 1–2, 15 January 2008, Pages 107-114 ; https://doi.org/10.1016/j.msea.2007.03.031[4] J. Martin Herrera Ramirez, Raul Perez Bustamante, Cesar Augusto Isaza Merino & Ana Maria Arizmendi Morquecho ; Thermal Spray Coatings ; DOI:10.1007/978-3-030-48122-3_7 chapter In book: Unconventional Techniques for the Production of Light Alloy and Composites (pp.103-127) 23 June 2020 .[5] Shalaka Shinde ;Sanjay Sampath;A Critical Analysis of the Tensile Adhesion Test for Thermally ; J Therm Spray Tech (2022) 31:2247–2279 https://doi.org/10.1007/s11666-022-01468-z [6] M.R. Dorfman, Chapter 22 - Thermal Spray Coatings, Handbook of Environmental Degradation of Materials (Third Edition)ed., M. Kutz, Ed., William Andrew Publishing, 2018 p 469–488[7] A. Vardelle, C. Moreau, J. Akedo, H. Ashrafizadeh, C.C. Berndt, J.O. Berghaus, M. Boulos, J. Brogan, A.C. Bourtsalas and A. Dolatabadi, The 2016 Thermal Spray Roadmap, J. Therm. Spray. Techn., 2016, 25(8), p 1376–1440.[8] P.L. Fauchais, J.V. Heberlein and M.I. Boulos, Thermal Spray Fundamentals: from Powder to Part, Springer Science & Business Media, 2014[9]D.R. Clarke, M. Oechsner and N.P. Padture, Thermal-Barrier Coatings for more Efficient Gas-Turbine Engines, MRS Bull., 2012, 37(10), p 891–902.[10] C.-J. Li, G.-J. Yang and C.-X. Li, Development of Particle Interface Bonding in Thermal Spray Coatings: A Review, J. Therm. Spray. Techn., 2013, 22(2–3), p- 192–206.[11] L. Pawlowski, The Science and Engineering of Thermal Spray Coatings, John Wiley & Sons, 2008.

A. Lakshmikanthan; S. Angadi ; V. Malik ; K. Kuldeep; Saxena ; « Mechanical and Tribological Properties of Aluminum-Based Metal-Matrix Composites” ; September 2022 ; Materials ; DOI:10.3390/ma15176111
L. Milosan; T. Bedő ; C. Gabor ; D. Munteanu ; M. Pop ; D. Catana ; M. Cosnita ; B. Varga ; Characterization of Aluminum Alloy–Silicon Carbide Functionally Graded Materials Developed by Centrifugal Casting Process ; Appl. Sci. 2021, 11(4), 1625; https://doi.org/10.3390/app11041625
H. Arami, R. Khalifehzadeh, M. Akbari, F. Khomamizadeh ^; Microporosity control and thermal-fatigue resistance of A319 aluminum foundry alloy; Materials Science and Engineering: A; Volume 472, Issues 1–2, 15 January 2008, Pages 107–114; https://doi.org/10.1016/j.msea.2007.03.031
J. Martin Herrera Ramirez, Raul Perez Bustamante, Cesar Augusto Isaza Merino & Ana Maria Arizmendi Morquecho; Thermal Spray Coatings; DOI:10.1007/978-3-030-48122-3_7 chapter In book: Unconventional Techniques for the Production of Light Alloy and Composites (pp.103–127) 23 June 2020.
Shalaka Shinde;Sanjay Sampath;A Critical Analysis of the Tensile Adhesion Test for Thermally ; J Therm Spray Tech (2022) 31:2247–2279 https://doi.org/10.1007/s11666-022-01468-z
M.R. Dorfman, Chap. 22 - Thermal Spray Coatings, Handbook of Environmental Degradation of Materials (Third Edition)ed., M. Kutz, Ed., William Andrew Publishing, 2018 p 469–488
A. Vardelle, C. Moreau, J. Akedo, H. Ashrafizadeh, C.C. Berndt, J.O. Berghaus, M. Boulos, J. Brogan, A.C. Bourtsalas and A. Dolatabadi, The 2016 Thermal Spray Roadmap, J. Therm. Spray. Techn., 2016, 25(8), p 1376–1440.
P.L. Fauchais, J.V. Heberlein and M.I. Boulos, Thermal Spray Fundamentals: from Powder to Part, Springer Science & Business Media, 2014
D.R. Clarke, M. Oechsner and N.P. Padture, Thermal-Barrier Coatings for more Efficient Gas-Turbine Engines, MRS Bull., 2012, 37(10), p 891–902.
C.-J. Li, G.-J. Yang and C.-X. Li, Development of Particle Interface Bonding in Thermal Spray Coatings: A Review, J. Therm. Spray. Techn., 2013, 22(2–3), p- 192–206.
L. Pawlowski, The Science and Engineering of Thermal Spray Coatings, John Wiley & Sons, 2008.
Sagar Amin; Hemant Panchal ; A Review on Thermal Spray Coating Processes ; International Journal of Current Trends in Engineering & Research ;Volume 2 Issue 4, April 2016 pp. 556–563
A. Sadki1, M.L.Hattali, M. A. Bradai, R. Younes, N.Mesrati ; Characterization and Modeling of the Mechanical Behavior of Aeronautical Alloy Based Composite; Universal Journal of Chemistry 4(1): 10–19, 2016 http://www.hrpub.org DOI: 10.13189/ ujc.2016.040102
A. Sadki; Rassim Younes ; Bradai Mohand Amokrane ; Nadir Mesrati ; Effect of NiAl Bond Layer on the Wear Resistance of an Austenitic Stainless Steel Coating Obtained by Arc Spray Process- May 2023;SAE International Journal of Materials and Manufacturing 16(4) ; DOI:10.4271/05-16-04-0022
P. Patel, Sima A. Alidokht,; N. Sharifi, A. Roy, K. Harrington, P. Stoyanov, Microstructural and Tribological Behavior of Thermal Spray CrMnFeCoNi High Entropy Alloy Coatings; Volume 31, pages 1285–1301, (2022); springer link.
Jandin, G., et al. "Correlations between operating conditions, microstructure and mechanical properties of twin wire arc sprayed steel coatings." Materials Science and Engineering: A 349.1-2 (2003): 298–305.
Planche, M. P., R. Bolot, and C. Coddet. "In-flight characteristics of plasma sprayed alumina particles: measurements, modeling, and comparison." Journal of thermal spray technology 12.1 (2003): 101–111.
Y. Han, Z. Zhu d, B. Zhang, Y. Chu, Y. Zhang, J. Fan, Effects of process parameters of vacuum pre-oxidation on the microstructural evolution of CoCrAlY coating deposited by HVOF, Journal of Alloys and Compounds 735 (2018) 547e559
L. Qiaoa, Y. Wua, S. Honga, J. Zhang, W.Shia, Y. Zheng, Relationships between spray parameters, microstructures and ultrasonic cavitation erosion behavior of HVOF sprayed Fe-based amorphous/ nanocrystalline coatings, Ultrasonics - Sonochemistry 39 (2017) 39–46
A.G.M. Pukasiewicz, H.E. de Boer, G.B. Sucharski, R.F. Vaz, L.A.J. Procopiak, The influence of HVOF spraying parameters on the microstructure, residual stress and cavitation resistance of FeMnCrSi coatings, Surface & Coatings Technology 327 (2017) 158–166
K. Yang, M. Fukumoto, T. Yasui, M. Yamada, Role of substrate temperature on microstructure formation in plasma-sprayed splats, Surface & Coatings Technology 214 (2013) 138–143
O. Kovářík, P.Haušild, J. Siegl, T. Chráska, J.Matějíček, Z. Pala, M. Boulos, The influence of substrate temperature on properties of APS and VPS W coatings, Surface & Coatings Technology 268 (2015) 7–14.
Z. Arabgol, M. Villa Vidaller, H. Assadi, F. Gartner, T. Klassen, Influence of thermal properties and temperature of substrate on the quality of cold-sprayed deposits, Acta Materialia 127 (2017) 287e301
J. Wang, X.T. Luo, C. J. Li, N. Ma, M. Takahashi, Effect of substrate temperature on the microstructure and interface bonding formation of plasma sprayed Ni20Cr splat, Surface & Coatings Technology,371(2019)36–46

No competing interests reported.

Thermal Cycle Behavior of the Interface of AG3/75E/55E and AU4G/75E/55E Multimaterials Elaborated by Thermal Spray

Status:

Version 1

Abstract

Figures

1 INTRODUCTION

2 EXPERIMENTAL PROCEDURES

3 RESULTS

CONCLUSIONS

Declarations

Author Contribution

References

Additional Declarations

Status:

Version 1