Study of Particle Properties of Different Steels Sprayed by Arc Spray Process

Abstract

Thermally sprayed coatings are employed for many purposes, as corrosion protection, wear resistance improvement, resistance to high temperatures, and others. The coating performance depends on its morphology, which is composed by splats, pores, oxide inclusions, and entrapped unmelted or resolidified particles. In arc spray process (ASP), the heat source is the arc electric obtained from the contact of two consumable metallic wires with different electric potentials, and the carrier gas is the compressed air. The velocity, dimensions, and thermal characteristics of the droplets sprayed are related to the morphology and properties of the coating. The main goal of this research is to evaluate how the velocity, temperature, and particle size are modified by the chemical composition of different materials (carbon steel, stainless steels, and FeMnCrSiNi alloy). The intention is to predict how the modification of the process parameters will change the particles properties. The materials had similar behavior tendencies during the flight: the velocity increased to a peak value then decreased, but this maximum value was different for materials with different particle size. The particles’ size did not present significant differences during the flight; and the particles cooled down as they moved away from the gun, except the austenitic stainless steel and the FeMnCrSiNi alloy, which increased the droplets temperature during the travel. These alloys also presented more variation in chemical composition during flight.

Thermal Spraying of FeMnCrSi Alloys: An Overview

“…The temperature of particles sprayed by ASP had the distribution at the distance of 200 mm presented in Figure 3, and their behavior during the flight was increase the value from 1998±157 ˚C at 40 mm to 2027±162 ˚C at 200 mm, variation of 1%, which is related to the alloy chemical composition and the amount of oxidizing alloy elements, such as chromium, manganese, and silicon, which reacts is an exothermic chemical reaction [24]. Pukasiewicz et al [26] presented the morphology of FeMnCrSi ASP coatings, Figure 4, with typical coatings elements: lamellae, pores, oxide layers, and pre-solidified particles.…”

“…In-flight particle properties have a severe influence on the morphology and, consequently, on the coating properties. Vaz et al [24] compared the in-flight particle properties of the FeMnCrSi and other steel alloys sprayed by ASP, using a Sulzer Metco 300 (Westburry, NY, USA). The velocity, temperature, and diameter of particles were measured by a Tecnar DPV Evolution (Saint Bruno, QC, Canada) equipment.…”

“…This experiment indicates that the distance of 200 mm is the best position to place the substrate to be coated with FeMnCrSi by ASP, since the highest velocity promotes a denser coating, which has a direct influence on the cavitation performance of the coating. [24].…”

Welding and Thermal Spray Processes for Maintenance of Hydraulic Turbine Runners: Case Studies

“…The compressive residual stress of 205 MPa was seen on FeMnCrSi HVOF sprayed, which is related to the improvement of the cavitation resistance 19.1 mg/h [37]. Vaz et al [38], using the ASP (Arc Spraying Process), indicated the best standoff distance for FeMnCrSi [33], reaching the highest Kinetic Energy for the particles in flight at 200 mm, with velocity 150 m/s. Mayer et al [39] indicated the synergism between corrosion/cavitation Cr3C2-NiCr alloys, with higher mass loss by cavitation on NaCl solution than on deionized water.…”