Tribological Behavior of Ni-Based Coatings Deposited via Spray and Fuse Technique

Jiménez Hernando,Alfonso José Edgar,Olaya Jhon Jairo

doi:10.3390/coatings10111080

Jiménez Hernando, Alfonso José Edgar + Show 1 more

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https://doi.org/10.3390/coatings10111080

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Abstract

The tribological behavior of Ni-based coatings was analyzed. The coatings were deposited on grey cast iron substrates in a spray and fuse process using Superjet Eutalloy deposition equipment, varying the oxygen flow conditions in the flame. By means of the X-ray diffraction (XRD) technique, the crystal structure of the coatings was determined. The XRD patterns show the crystalline phases with principal reflections for Ni in the planes (111) and (222). Crystalline properties such as the orientation coefficient, crystallite size, and macrostrain showed the relationship with tribological and mechanical properties such as the dry wear rate and the microhardness. The microhardness was analyzed on the surface and on cross sections of the coatings by means of a Knoop microhardness tester. The topography and the morphological characteristics of the coatings and the tribo-surfaces were exanimated using scanning electron microscopy (SEM) and confocal microscopy, while the chemical composition was measured by means of energy-dispersive X-ray spectroscopy (EDS). The tribological behavior of the coatings was examined via the scratch cohesion–adhesion test, using cross sections of the coatings. Furthermore, adhesion and abrasion wear tests were carried out, using the pin-on-disk method, under the ASTM G99 standard and the ASTM G65 standard, respectively. The wear rate of the coatings showed a strong relation to the porosity in the metal matrix, which was previously determined via electrochemical characterization techniques.

Highlights

Thermal spray techniques have been widely used for depositing protective coatings, because of their relatively low-cost production, versatility, and the different types of substrates that can be used [1]
Using the spray and fuse thermal spray technique, Ni-based coatings were deposited onto grey cast iron cylindrical substrates of 41 mm in diameter and 4 mm in thickness
In the deposition process of the coatings, the grey cast iron substrate was preheated to a temperature of between 500 and 600 ◦ C, and the filler material was sprayed onto the substrate

Summary

Introduction

Thermal spray techniques have been widely used for depositing protective coatings, because of their relatively low-cost production, versatility, and the different types of substrates that can be used [1]. The spray and fuse technique is a two-step deposition process that falls under the thermal spray techniques This technique is an economical process for applying protective coatings with a relatively low degree of porosity (approximately 10–20%) and good adhesion [1,2,3]. Tribological studies are of great interest for understanding and predicting the behavior of coatings in erosive-corrosive environments so as to estimate the useful lifetime and the type of protection provided by coatings for the surface to be protected. Several authors, such as Fazel, Sugiarti, Wang, and Lee, among others, have studied the mechanical, tribological, and microstructural properties

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