Effects and Interplays of Spray Angle and Stand-off Distance on the Sliding Wear Behavior of HVOF WC-17Co Coatings

Abstract

The state of particle impact (velocity and temperature) significantly affects the coating's microstructural, mechanical properties and wear performance. The spray stand-off distance and spray angle dictate particle velocity components and temperature at impact. This work aims in advancing the understanding of their effect and interplay in regard to the sliding wear performance as well as the mechanisms of wear themselves of HVOF-sprayed WC-17Co coatings. Dry sliding wear resistance was evaluated by a pin-on-disk test, and significant interplay between the spray parameters was observed. A large number of experiments in a full-factorial manner provided insights into the progressive tribofilm build-up and wear damage modes and allowed for proposing mechanisms regarding their occurrence. Small deviations from the normal spray angle at long stand-off distances proved to be beneficial for the wear performance of the coatings. The highest friction coefficient and most aggressive wear damage were observed in coatings with a rich coverage of the wear track with a tribofilm. The phase composition of the coatings proved to be the principal contributor in the wear performance.

Effect of stand-off distance (SOD) on damping properties of atmospheric plasma sprayed alumina-zirconia ceramic coatings

“…based high temperature resistant with superior mechanical properties ceramic coatings have been widely used in gas turbines for power generation and propulsion applications in aerospace and space sectors as these coatings have a great influence on the fuel efficiency [8][9][10][11]. Several investigations are carried out with thermally sprayed high-temperature oxide-based coatings in terms of microstructures-obtained properties and its effect on thermal spray parameters applied [12][13][14][15][16][17][18]. The effect of SOD on the microstructure and mechanical properties of thermally sprayed metal and ceramic coatings such as hardness, elastic modulus, strength, fracture toughness and tribological properties are widely studied [19][20][21][22][23].…”

CoCrFeMnNi0.8V/Cr3C2-Ni20Cr High-Entropy Alloy Composite Thermal Spray Coating: Comparison with Monolithic CoCrFeMnNi0.8V and Cr3C2-Ni20Cr Coatings

“…The coatings were applied with a proprietary "compact High Velocity Oxy-Fuel (HVOF)" technique [27], featuring a nozzle designed to accelerate exhaust gases to almost trice the speed of sound (Mach 2.7). The in-house optimization of the HVOF gun's parameters focused on producing the ideal microstructure, characterized by low porosity and reduced mean free path of the binder, while maximizing the volume of Cr-C and achieving maximum microhardness for the coatings.…”

Sliding Wear of Conventional and Suspension Sprayed Nanocomposite WC-Co Coatings: An Invited Review

“…Common compositions for WC cermet coatings are WC-12Co, WC-17Co, WC-10Co-4Cr and WC-12Ni (Ref 3, 5, 19, 20, 26) (note that all compositions are in wt.%). Figure 15 Table 4 (Ref 32,108,116,117,[120][121][122][123][124][125][126][127] presents the wear performance of WC cermet coatings with respect to binder composition. The cermet coating composed of WC-NiCrBSi is not well-documented in terms of its sliding wear in comparison to WC-12Co coatings (Table 4).…”