Erosion tribo-performance of HVOF deposited Stellite-6 and Colmonoy-88 micron layers on SS-316L

doi:10.1016/j.triboint.2018.06.004

Tribology International

Volume 147, July 2020, 105262

https://doi.org/10.1016/j.triboint.2018.06.004 Get rights and content

Highlights

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Microstructure of Stellite-6 and Colmonoy-88 deposited surfaces shows presence of inter-lamellae splates.
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Microhardness of SS-316 L was improved about 2.5–3.2 times with deposition of Stellite-6 and Colmonoy-88.
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Colmonoy-88 sprayed SS-316L showed lower erosion wear as compare to Stellite-6 sprayed SS-316L.
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The maximum erosion was observed at 30° impact angle arrangement for SS-316 L and Stellite-6.
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Maximum erosion wear of Colmonoy-88 was observed at 60°.

Abstract

The present study deals with the analysis of erosion tribo-performance of Stellite-6 and Colmonoy-88 micron layers deposited on stainless steel 316 L by using high-velocity oxygen–fuel (HVOF) process. The average roughness of Stellite-6 and Colmonoy-88 deposited SS-316 L was measured as 5.69 and 6.67 μm respectively. The crack toughness of Stellite-6 and Colmonoy-88 deposited surface was evaluated as 19.8 ± 0.56 and 30.1 ± 0.29 MPa m^1/2 respectively. Erosion wear experiments were performed by using a Ducom slurry pot tester at different process parameters. Results show that the relative erosion wear of SS-316 L and Stellite-6 was observed maximum at 30° impact angle whereas relative erosion of Colmonoy-88 was found maximum at 60°. Microhardness of SS-316 L was improved about 2.5–3.2 times with deposition of Stellite-6 and Colmonoy-88.

Introduction

The erosion wear prediction in slurry pumps has been recognized in various industries from many years. Erosion wear depends upon a variety of parameters such as velocity, time, concentration, impingement angle, target properties, etc. [1,2]. Erosion wear of materials also depends upon the particulate properties such as size, shape, density, etc. In recent years, researchers have shown a great interest in the analysis of erosion wear by varying the process parameters. On the other hand, very few researchers have performed the erosion wear studies based on particle shape [[3], [4], [5]]. They found that the circularity factor (CF) or shape factor (SF) of sand lies in range 0.56–0.75 [3,4]. Thus, the shape factor can play an important role in the analysis of erosion wear.

The sand particles flowing through slurry pumps, turbines and other hydraulic machinery generate erosion wear. To avoid the erosion wear, different types of coatings were performed on different pump materials. Various coating deposition processes or techniques are used in industries. Among those processes, the high-velocity oxy-fuel (HVOF) spraying process is widely used to deposit coating on the components of hydraulic machinery. Moreover, HVOF is a universally recommended process to deposit the various coatings for prevention or reduction of abrasion, erosion, and corrosion. Arji et al. [6] had performed an experimental study on erosion wear of Stellite-6 by using the sand as an erodent. Yao [7] studied the surface tribology of Ni-based (NiCrBSi–WC(Co)) coating. Results show that 50% addition of WC(Co) content significantly improved the wear performance of NiCrBSi coating. Karimi et al. [8] studied the porosity of Ni-based (NiCrBSi) flame sprayed coatings. They reported that porosity of this coating was improved in range 11.7–1.9% after going through remelting process. Aubry et al. [9] reported the various mechanical properties of Stellite and Colmonoy coatings deposited by cladding process. Li et al. [10] studied the corrosion of Ni-based (NiCrBSiFeCoC) coating. They also studied that coating possesses carbides phases namely Cr₂₃C₆, Cr₇C₃ and WC which contributes to improve the microhardness. Gnanasekaran et al. [11] investigated the mechanical and tribological properties of Colmonoy-5 coating deposited on 316-LN steel. They performed a laser hardfacing to deposit the Colmonoy-5 coating on 316-LN. They found that wear resistance of 316-LN steel was improved by 20 times with deposition of Colmonoy-5. Also, it is reported in literature that the erosion wear of thermal spray coating depends on its mechanical properties (such as fracture toughness, microhardness, elastic modulus etc.) [12].

From above literature, it can be concluded that Ni- and Co-based coatings were found to be promising in tribological applications. Stellite-6 and Colmonoy-88 haven't widely used for high erosion duty conditions in hydraulic machinery. So, the present study has been carried out to perform a comparative analysis on erosion wear of Stellite-6 and Colmonoy-88 coatings deposited by high-velocity oxy-fuel (HVOF) spraying process. This study is focused on mechanical as well tribological behavior of both coatings.

Section snippets

Base materials

In the present study, Stainless steel (SS) 316 L grade was used as a base material. The geometry of sample specimen is shown in Fig. 1. Test specimens are of dimensions- 67.5 × 25 × 5 mm and a concentric hole of 8 mm diameter. A comparison was made on the basis chemical composition data of SS-316 L provided by the metal supplier and optical emission spectrometer (manufactured by Foundry master, Oxford Instruments, Uedem, Germany) for precise measurement, as represented in Table 1.

Erodent material

In the present

Tribology experiments

An erosion pot tester (Ducom: TR-401, Bangalore, India) was used to perform the erosion wear experiments. Fig. 5 shows the schematic diagram of the erosion wear pot tester. A cylindrical pot of capacity of 2000 ml was used to prepare the slurry by stirring it for 25 min at 330 rev/min. A highly sensitive electronic weighing machine with least count of 0.0001 g was used to measure the weight loss from specimens which gave the quantity of eroded material. The experiments were performed at

Microhardness of bare and coated surface

A MVH-1 digital microhardness tester (manufactured by Metatech Pune, India) was used to measure the microhardness of SS-316 L grade. Typical indent observed on the surface of SS-316 L is shown in Fig. 7. The parallel and perpendicular Vickers diagonals were measured as 72.84 and 69.61 μm respectively. Average microhardness of SS-316 L in four trials was found as 196H V. (500 gm). The surface microhardness of coated specimens was also tested along the vertical axis (as shown in Fig. 8). It was

Conclusion

The present study was aimed to analyze the erosion failure of Stellite-6 and Colomony-88 coatings deposited on SS-316 L by HVOF process. The erosion wear experiments were carried out at different rotational speeds of impeller, solid concentrations of sand slurry, experimental time durations, shape factors, impact angles to match the actual conditions in a slurry pot tester. The following conclusions can be drawn on the basis of experimental results:

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The average roughness of Stellite-6 and

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^☆: This paper was presented at the ASIATRIB2018.

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Erosion tribo-performance of HVOF deposited Stellite-6 and Colmonoy-88 micron layers on SS-316L☆

Highlights

Abstract

Introduction

Section snippets

Base materials

Erodent material

Tribology experiments

Microhardness of bare and coated surface

Conclusion

Wear

Wear

Powder Technol

Wear

Wear

Physic Procedia

Wear

Wear

Wear

Tribol Int

Tribol Int

Tribol Int