View of AN INVESTIGATION ON ABRASIVE WEAR BEHAVIOUR OF HVOF THERMALLY SPRAYED WC-10CO-4CR AND WC-20CR-7NI COATINGS

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Vol.04, Issue 12, December 2019, Available Online: www.ajeee.co.in/index.php/AJEEE AN INVESTIGATION ON ABRASIVE WEAR BEHAVIOUR OF HVOF THERMALLY

SPRAYED WC-10CO-4CR AND WC-20CR-7NI COATINGS

1Sharda Soni, ¹Research Scholar,

2Prof. Pragyan Jain, ²HOD, ME, GGITS Jabalpur, MP, India

3Prof. Tribhuwan Kishore Mishra,

3Dept. of Mechanical Engineering, Gyan Ganga Institute of Technology and Science, Jabalpur

Abstract:- In this work abrasive wear tests WC-10CO-4Cr and WC-20Cr-7N coated specimens were performed against a silicon carbide abrasive media. High-Velocity Oxy-Fuel flame spraying technique (HVOF) was used to deposit the coating on MS then these coated samples were characterized using scanning electron microscopy, X-ray diffraction (XRD), coefficient of friction (COF), hardness and porosity. The experiment result showsWC-10CO- 4Cr coating suffered minimum weight loss, higher friction coefficient. Maximum hardness and minimum porosity were observed in WC-10CO-4Cr coating. The SEM image shows the bright and dark grey regions corresponding to the tungsten carbide and cobalt binder phase. Cutting, micro-cutting, and delamination wear mechanisms were observed in the worn-out surface.

1. INTRODUCTION

Steel is a broadly utilized material for an engineering application as a result of its accessibility in the market as well as in view of the accessible compounds and levels of steels give a wide scope of properties not found in some other group of materials. Carbon and other alloying components present in steel have a momentous impact on the microstructure changes and mechanical and tribological properties, also. Further wide scope of warm showering could be received to differ microstructure and mechanical and tribological properties in these sorts of materials.

Financial perspectives assume an imperative job in the choice of material.

Therefore, there is a necessity of hard material with which is least expensive, and most promptly accessible. In India the vast majority of the work is done on the low carbon and medium carbon steel and, because of expansion of alloying components the expense of steel increments, gentle steel gives an answer of this issue since the expense of mellow steel extremely low when contrasted with other composite steel. Determination of appropriate material ought to be made simply after cautious thought of part configuration, wear mode, material, and ecological associations.

Mild steels are the right crude material decision when high protection from burdens, surface weight and wear is required. Their quality after fire solidifying

meets the requesting necessities of wear obstruction steels. At the point when mild steel is covered by the (1060 HOGONAS) powder by the fire showering system it builds hardness of steel as it were. Run of the mill utilization of mild steels are for assembling of the street and horticultural hardware sharp edges, track sections for ranger service machines, snow furrow wear plate, smashers and different procedure apparatus and a wide range of machine parts requiring high quality.

It is likewise utilized in the car so as to make the vehicle body and suspension. Mild steels can be worked in both the hot and cold condition. The molding and joining of mild steels can be effectively cultivated utilizing typical workshop techniques. The low combination and pollution substance of mild steels make them impervious to hot splitting. Mild steels are likewise entirely reasonable for surface solidifying. In this way, there is a need to analyze the impact of powder covering on mechanical and tribological practices of steels. The formation of mild steel was not a medium- term advancement. It took specialists and researchers numerous years to consummate the correct recipe just as basic security.

Wear happens at the surface and the closed surface. Improving the property of surfaces is the present pattern for taking care of the present wear issues, instead of the improvement of new wear- safe mass materials. Along these lines, it

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Vol.04, Issue 12, December 2019, Available Online: www.ajeee.co.in/index.php/AJEEE is the objective to structure a framework

including undesirable mechanical activity on a surface that causes a material evacuation. To shield surfaces from weakening in their utilization condition, it is gone for fitting the properties of contact surfaces of building parts, for example, moving contact heading, riggings, cams and tappets to improve their capacity.

In this way, to changing the surface attributes (better than those of the mass material) for better use properties in the applications including wear, surface building is the most encouraging approach to acquire higher usefulness in reaching machine components. term advancement. It took specialists and researchers numerous years to consummate the correct recipe just as basic security. Wear happens at the surface and the closed surface.

Improving the property of surfaces is the present pattern for taking care of the present wear issues, instead of the improvement of new wear-safe mass materials.

Along these lines, it is the objective to structure a framework including undesirable mechanical activity on a surface that causes a material evacuation. To shield surfaces from weakening in their utilization condition, it is gone for fitting the properties of contact surfaces of building parts, for example, moving contact heading, riggings, cams and tappets to improve their capacity. In this way, to changing the surface attributes (better than those of the mass material) for better use properties in the applications including wear, surface building is the most encouraging approach to acquire higher usefulness in reaching machine components.

2. LITERATURE REVIEW

1. RavindraIshwar Badiger et. al (2017) investigated the mechanical properties of the Inconel-625 welded joint developed through microwave hybrid heating. Inconel-625 is a nickel- based superalloy which is strengthened by the addition of chromium, molybdenum, niobium and carbon. Inconel-625 is used

effectively utilized to join Inconel- 625 plates with a hybrid heating technique. The welded joints of Inconel-625 are carried out in two phases, which are metallurgical and mechanical characterization.

Average ultimate tensile strength and flexural strength of the developed joints were estimated at 375 and 377 Mparespectively.

Average impact toughness of microwave-induced joints observed to be 18j.

2. S. Sharma et. al (2016) investigated on improving abrasive wear, structure, properties, and co-based Coating using La2O3 addition. In this experiment, the Co-based alloy is modified with La2O3, which is coated by the high-velocity oxy-fuel (HVOF) spraying process. The coating materials basically are Ni, Co, and Fe based. The unmodified and La2O3 modified powder coatings are mainly showed three phases.

The result indicated that abrasive wear is found to increase with the increase in normal load and sliding rates. Analysis of the worn surfaces by scanning electron microscope images revealed cutting and plowing as the material removal mechanisms in these coatings under abrasive wear conditions used in this research.

3. Wolfgang Tillmann et. al. (2015) investigated on thermally sprayed fine structured WC-12Co coatings finished by ball burnishing and grinding to protect forming tools at against wear. In this experiment thermal spraying and HVOF coating technique is used to protect the surface of the forming tools against wear. The result showed in contrast to the cold work steel, both coated dies, the ball burnished as well as the ground die, showed a significantly better wear performance after the forming of 10,000 parts.

3. OBJECTIVE OF WORK

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Vol.04, Issue 12, December 2019, Available Online: www.ajeee.co.in/index.php/AJEEE WC-10Co-4Cr and WC-20Cr-7Nicoating

was not found in a common platform. So there is still a need to compare the wear, micro structural and mechanical properties. of these two coatings, The aim of this project to study the abrasivewear behavior of WC-10Co-4Cr and WC-20Cr- 7NiHVOF sprayed coating on the pin on disk wear tester at dry sliding condition.

And find out the cause of wear

mechanism at different stages and correlate to microstructure, XRD and other mechanical properties like toughness and hardness.

4. METHODOLOGY

The aim of this chapter is to explain the methodology, which is used to perform the wear test, Hardness, porosity, SEM, XRD and correlate the results.

4.1 Sample Preparation

Mild steel is used to prepare the coating specimen 1020 mild steel was purchased from Nextgen steel and alloy Mumbai.

Lathe and taxa machine was used to

prepare the sample in GGITS workshop.

Finally diameter 12. Diameter 24mm and 5cm×5cm.Sample was prepared for coating deposition. The view showing fabricated specimens is presented in figure No.4.1

Figure 4.1 coated cylindrical specimen 25 4.2 Coating deposition

WC-10Co-4Cr and WC-20Cr-7Nipowder were used for deposition the coating. These coatings were deposited MECPL Jodhpur Rajasthan by using the high-velocity Oxy-fuel (HVOF) technique. Coating parameter is mention in Table No.1

Table 1 HVOF spray deposition parameters

4.3 SEM (scanning electron microscopic), XRD and porosity Test.

Coated specimens were characterized by using the SEM JEOLJSM-6380A scanning

electron microscope. SEM test and XRD were performed at VNIT Nagpur. of coated sample X-Ray diffraction (XRD) test were performed by using 9kg wattXRDRiguke-

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Vol.04, Issue 12, December 2019, Available Online: www.ajeee.co.in/index.php/AJEEE Japan.XRD machine by using Cu-K Alfa

along with 1.5406A* radiation. Porosity was calculated by Image J software by

using the area count method. Average of 3 reading was considered to final out the porosity.

Figure 4.2 JEOLJSM-6380A scanning electron microscope 4.4Micro-Hardness

Vickermicrohardness tester was used to final out the micro-hardness by using 0.3kg load for 15 sec as per ASTME 384-2016 standard. The reading was taken at different places in the cross-section.

Figure 4.3 Hardness Tester 5. RESULT AND DISCUSSION

The aim of this chapter to discuss the result obtained by performing various test like SEM, XRD, Microhardness, porosity and wear test. After that these

presentation in graphically manner for comparison.

5.1 SEM Images of feedstock powder

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Vol.04, Issue 12, December 2019, Available Online: www.ajeee.co.in/index.php/AJEEE

Figure 5.1 Microstructure of powder Scanning electron microscopy (SEM)

images are shown by figure No.5.1(a),(b).These powder having spherical shapes. WC-10Co-4Cr shows dense structure and WC accumulated CO binder face. WC-10Co-4Cr and Coating WC20-Cr-7Ni powder shows a little bit of porous structure and having weaker binder face..WC-20Cr-7Ni has a weaker binder segment then the WC-10CO- 4Cr.Dark graypatches represents the existence of WC and combined and enclosed by nickel particle.

5.2 SEM images of WC-10CO-4Cr and WC-20Cr-7Ni Coating

Scanning electron micro scoping (SEM) images WC-10Co-4Cr and WC-20Cr- 7Nishown in figure No.5.2 It was

absorbed tungsten carbide homogeneously dispersed in cobalt matrix coating WC10CO4Cr shows dense microstructure as compare to coating WC20Cr7Ni due to excellent bounding

WC-10Co-4Cr shows refine

microstructure minimum porous and micro-cracks. Bright patches shows the presence of WC and grey patches presence shows the CO.WC-20Cr-7Ni Coating have a porous structure, micro cracks and some cavities. Some unmelt particles were also seen in the coating. It may be due to the presence of a weaker Cr binder face. Three-D images of coating (fig 5.3) show the fine and dense microstructure of WC-10CO-4Cr coating and WC-20Cr-7Ni Coating.

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Figure 5.2 Microstructure of(a) WC-10CO-4Cr and (b) WC-20Cr-7Ni Coating Coating

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Figure 5.3 3-D Topology of WC-10CO-4Cr and WC-20Cr-7Ni Coating 5.3 Porosity

The porosity of WC-10CO-4Cr and WC- 20Cr-7Ni Coating was found by ImageJ software. Threshold Image of coatings is shown in fig. 5.4. The porosity of WC- 10CO-4Cr was minimum and 4.5% and WC-20Cr-7Ni Coating shows higher porosity that is 6.8%. It is 1.5 times

higher than the WC-10Co-4Cr coating.

The percentage area method was used for calculating the porosity. The minimum porosity of WC-10CO-4Cr is attributed to dense microstructure. and WC-20Cr-7Ni Coating. The WC-20Cr-7Ni coating shows porous and microcracks due to the presence of a weaker phase of Cr.

Figure 5.4 Threshold Images of WC-10CO-4Cr and WC-20Cr-7Ni Coating Coating 5.4 XRD of Coating

Figure No.5.5X-Ray diffraction shows the (XRD) of the Coated sample shows the XRD WC-10CO-4Crshows a major peak of WC and minor peak of CO New face

W2Cface also same in coating. It is due to the decomposition of WC into liquid WC and W2C having bit effect and XRD.WC- 20Cr-7Ni shows a major peak as a Cr3C2 and minor peak NiCr presence of Cr2C2

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Vol.04, Issue 12, December 2019, Available Online: www.ajeee.co.in/index.php/AJEEE shows the decomposition of tungsten and

Cr and formsa new face. Some other face Cr7C3wasalso seen in the XRD pattern in small amounts.

5.5 Hardness of Coating

Figure No.5.6 Shows the microhardness of WC-10CO-4Cr and WC-20Cr-7Ni Coating. The Coating WC10CO4Cr shows maximum hardness and that is 38.75%

higher than the WC-20Cr-7Ni coating.

Result clear indicates that coating WC10CO4Cr shows the higher hardness because of WC- CO stronger bond, and dense microstructure.

Table 2 Hardness

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Figure 5.5 Microhardness of WC-10CO-4Cr and WC-20Cr-7Ni Coating 5.6 Wear

Wear in terms of weight loss of coating WC-10Co-4Cr and coating WC-20Cr-7Ni was measured at different applied load 20N and 40N was shows in figure No 5.7(a-b). The WC-10CO-4Cr coating shows minimum weight loss at both the load. WC-20Cr-7Ni coating showed higher wear. All the coating shows higher weight loss at 40 N loads as comparedto 20 N loads. The minimum wear of WC-10Co- 4Cr can be attributed dense

microstructure and minimum porosity.

Coefficients of friction of coating are shown in fig 5.8 (a-b) at 20N load and 40 N loads. Initially, coefficient friction increases due to higher stress-induced at junction of two opposite surfaces. It is due to less contact area. After some wear run period wear rate gets steady rate In this stage wear rate reduces due to the formation of the tribo oxide layer. WC- 20Cr-7Ni shows a higher coefficient of friction at both the load condition.

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Figure 5.6 Wear (weight Loss)

Figure 5.7 Coefficient of Friction 5.7 Analysis of wear out surface:

Figure No5.9 (a-b) shows the SEM image and #-D topology of wear worn out

coating small groove with narrow with is clearly seen in the same image. This is because of the higher hardness of WC-

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Vol.04, Issue 12, December 2019, Available Online: www.ajeee.co.in/index.php/AJEEE media. Micro cutting and delamination

were observed in WC-20Cr-7Ni coating.

Micro cracks were also seen in SEM image. A large amount of coated martial

was removed from the surface due week binder Cr-Ni phaseWC-10Co-4Cr and coating WC-20Cr-7Ni.

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Figure 5.8 Wear outworn surface (a) WC-10CO-4Cr and (b)WC-20Cr-7Ni Coating at 40 N Load

6. CONCLUSION

On the basis of different results obtained by the experimental are shown below:-

1. WC-10Co-4Cr powder shows spherical shapes. WC-10Co-4Cr shows dense structure and WC accumulated CO binder face 2. WC10CO4Cr shows dense and

refine microstructure as compare to coating WC20Cr7Ni due to excellent bounding WC-10Co-4Cr with minimum porous and microcracks.

3. WC-20Cr-7Ni Coating shows higher porosity and it 1.5 times higher than the WC-10Co-4Cr coating.

4. XRD of WC-10CO-4Cr coating shows a major peak of WC and minor peak of CO New face W2C face. XRDWC-20Cr-7Ni shows a major peak as a Cr3C2 and minor peak NiCr.

5. WC-10CO-4Cr WC10-CO-4Cr shows maximum hardness and that is 38.75% higher than the WC-20Cr-7Ni coating.

6. WC-10CO-4Cr coating shows minimum weight loss and a higher coefficient of friction.

7. Cutting and delamination wear mechanism was observed in wear test.

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