Comparison of Ni-Based Self-Fluxing Remelted Coatings for Wear and Corrosion Applications

Abstract

The present study investigates the possibility to apply a vacuum furnace thermal post-treatment as an alternative solution for flame sprayed NiCrBSi wear and corrosion-resistant coatings, deposited on a low alloyed structural steel. The controlled atmosphere offers advantages regarding the fusion of the coating, porosity reduction, and degassing. An improvement of the applied heating-cooling cycle was performed through the variation of time and temperature. The best performing samples were selected by comparing their porosity and roughness values. The chosen samples were subsequently characterized regarding their microstructure, microhardness, sliding wear, and corrosion behavior. The experimental work confirms that the use of a vacuum remelting post-process reduces the porosity below 1% and leads to the formation of a larger quantity of hard boron-containing phases, promoting a significant decrease of the wear rate, while maintaining a good corrosion behavior.

Considerations on the Wear Behavior of Vacuum-Remelted ZrO2-Reinforced Self-Fluxing Ni-Based Thermally Sprayed Alloys

“…From the reflections at 50.2, the average tetragonal ZrO 2 crystallites were estimated to be about 67 nm, while the crystallites corresponding to the monoclinic phase, at 28.13 and 31.42 reflections, did not exceed 50 nm. The matrix aligns well with the classical phase interpretation for the Ni-based self-fluxing coatings [ 9 , 28 , 48 , 49 ] with a Ni-predominant phase and a σ Cr 3 Ni 5 Si 2 intermetallic compound. The coating’s post-processing led to the formation of hard CrB or Ni 3 B phases, whose presence is beneficial for the wear resistance of the coatings [ 11 , 22 , 28 , 50 ].…”

“…Since the content of the chemical elements cannot be varied indefinitely to improve the alloy or the resulting coatings, other developments in terms of novel deposition techniques, post-processing, or the introduction of reinforcing particles have been proposed. Although new methods, such as one-step atmospheric plasma spraying deposition [ 4 ] or powder laser cladding with no further post-processing, were recently reported [ 5 ], most of the state-of-the-art Ni-based self-fluxing alloy coatings need further remelting [ 6 , 7 , 8 , 9 ]. Post-processed coatings show improvement in fracture toughness and overall improved mechanical performance [ 10 ], as well as an increase in wear and corrosion resistance [ 11 ].…”

Factors Influencing Cavitation Erosion of NiCrSiB Hardfacings Deposited by Oxy-Acetylene Powder Welding on Grey Cast Iron

“…From the broad grades of metallic materials, the nickel alloys present promising applicability to cast iron workpieces [26]. The self-fluxing nickel alloys Ni-B-Si and Ni-Cr-B-Si can be deposited by different methods likewise oxy-acetylene powder welding [30], plasma arc welding [26,31], laser cladding [32], flame spraying [33,34], HVOF [35,36]. The low melting point and high substrate wettability guarantee effective deposition of NiCrSiB on different metallic substrates likewise steel [37], Ti6Al4V titanium alloy and cast iron [26,34].…”

Comparative Study of Corrosion Performance of LVOF-Sprayed Ni-Based Composite Coatings Produced Using Standard and Reducing Flame Spray Stoichiometry

“…At present, surface modification and coating technology is emerging as a cost-effective alternative for protecting engineering components against wear and corrosion damage [2]. Among various coating methods, thermal spraying is an advanced materials processing technique that involves heating or melting particles and depositing them onto the surface to produce thick coatings that improve the surface properties of materials [3,4]. Furthermore, one of the most common and cost-effective solutions to overcome the corrosion damage of industrial components is to apply a protective coating onto the component's surface [2,3].…”