Investigation of stand-off distance effect on structure, adhesion and hardness of copper coatings obtained by the APS technique

Goudarzi Masoumeh,Saviz Shahrooz,Salar Elahi Ahmad,Ghoranneviss Mahmood

doi:10.1007/s40094-018-0277-0

Goudarzi Masoumeh, Saviz Shahrooz + Show 2 more

Open Access

https://doi.org/10.1007/s40094-018-0277-0

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Abstract

The outbreak of the disease and infection in the hospital environment and medical equipment is one of the concerns of modern life. One of the effective ways for preventing and reducing the complications of infections is modification of the surface. Here, the handmade atmospheric plasma spray system is used for accumulating copper as an antibacterial agent on the 316L stainless steel substrate, which applies to hospital environment and medical equipment. As a durable coating with proper adhesion is needed on the substrate, the effect of stand-off distance (SOD) which is an important parameter of the spray on the microstructure, the hardness and adhesion of the copper coating on the 316L stainless steel were investigated. The structure and phase composition of copper depositions were investigated using scanning electron microscopy and X-ray diffraction. The adhesion and hardness of depositions are evidenced using the cross cut tester and Vickers hardness tester, respectively. The findings confirm that the voids in the coatings increase with increasing SOD, which leads to decreasing the hardness of coatings and also the adhesion strength between depositions and substrate. In addition, by increasing the SOD, the oxygen content and the size of grains in the lamellae (fine structure) of coatings also increase.

Highlights

The properties of depositions depend on spray methods [1, 2]
The handmade atmospheric plasma spray system is used for accumulating copper as an antibacterial agent on the 316L stainless steel substrate, which applies to hospital environment and medical equipment
As a durable coating with proper adhesion is needed on the substrate, the effect of stand-off distance (SOD) which is an important parameter of the spray on the microstructure, the hardness and adhesion of the copper coating on the 316L stainless steel were investigated

Summary

Introduction

The properties of depositions depend on spray methods [1, 2]. In recent years, the plasma spray technique is used for deposition of different coatings [3, 4]. The structural modification of the plasma torch can increase the power of plasma, which leads to more hardness of the coatings [5]. By adding helium or hydrogen gas to plasma gas, the power of plasma increases resulting in increase of coating hardness [6]. The bond between the splats inside the depositions and layer structure of coatings is the factor which defines the features of coatings achieved by the plasma spray method [7]. Roughness and temperature of substrates can improve solidification of copper droplets and modify the properties of depositions obtained by the plasma spray technique [9, 10]. The large diameter of the nozzle can improve cohesion between the lamellae in the coatings, because the dwelling time of particles in plasma torch increases [11]. The depositions of nickel-based alloy formed by plasma spray under low power may have certain features comparable to depositions formed by conventional plasma spray [12]

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