Comparative Study of Thermally Sprayed Coatings Under Different Types of Wear Conditions for Hard Chromium Replacement

Abstract

The tribological properties of part surfaces, namely their wear resistance and friction properties, are decisive in many cases for their proper function. To improve surface properties, it is possible to create hard, wear-resistant coatings by thermal spray technologies. With these versatile coating preparation technologies, part lifetime, reliability, and safety can be improved. In this study, the tribological properties of the HVOF-sprayed coatings WC-17%Co, WC-10%Co4%Cr, WC-15% NiMoCrFeCo, Cr 3 C 2 -25%NiCr, (Ti,Mo)(C,N)-37%NiCo, NiCrSiB, and AISI 316L and the plasma-sprayed Cr 2 O 3 coating were compared with the properties of electrolytic hard chrome and surface-hardened steel. Four different wear behavior tests were performed; the abrasive wear performance of the coatings was assessed using a dry sand/ rubber wheel test according to ASTM G-65 and a wet slurry abrasion test according to ASTM G-75, the sliding wear behavior was evaluated by pin-on-disk testing according to ASTM G-99, and the erosion wear resistance was measured for three impact angles. In all tests, the HVOF-sprayed hardmetal coatings exhibited superior properties and can be recommended as a replacement for traditional surface treatments. Due to its tendency to exhibit brittle cracking, the plasma-sprayed ceramic coating Cr 2 O 3 can only be recommended for purely abrasive wear conditions. The tested HVOF-sprayed metallic coatings, NiCrSiB and AISI 316L, did not have sufficient wear resistance compared with that of traditional surface treatment and should not be used under more demanding conditions. Based on the obtained data, the application possibilities and limitations of the reported coatings were determined.

Sliding wear investigation of suspension sprayed WC–Co nanocomposite coatings

“…Hence in comparing S-HVOF and HVOF-JK coatings; both of these factors i.e. i) the smaller carbide size (nanosized particles) in the wear debris which are predominantly W and WC in comparison to predominantly larger WC carbides for HVOF-JK, and ii) support of metal matrix for the nanosized particles which is similar to the effect of lower binder mean free path of the metal matrix as indicated by Houdková et al [12] and Chivavibul et al [28], resulted in a lower wear rate for both the ball and coating materials for the S-HVOF coatings ( Figure 10). …”

“…Hardmetals, such as WC-Co, Cr 3 C 2 -NiCr, WC-(W,Cr) 2 C-Ni, WC-NiCrBSi belong to one of the most important group of materials processed by thermal spray processes into coatings, which are predominantly applied for the protection against wear, such as abrasion, erosion and sliding [1][2][3][4][5][6][7][8][9][10][11][12][13].…”

“…Most research however has related to coatings sprayed from agglomerated and sintered powders, with the average particle size ranging from 10 μm to 50 μm and WC grain size ranging from 0.8 to 3.5 µm [1][2][3][4][5][6]. Optimization of these coatings has resulted in coating microstructures with negligible porosity, high fracture toughness and minimization of secondary carbide phases [1][2][3][4][5][6][9][10][11][12][13][14][15][16].…”

Influence of Post-treatment on the Microstructural and Tribomechanical Properties of Suspension Thermally Sprayed WC–12 wt%Co Nanocomposite Coatings

“…During spraying of WC-Co powders, significant changes in the chemical and phase compositions can occur [1]. The past two decades have seen extensive research in optimizing the feedstock powder characteristics, process parameters and post-treatments of wear-resistant hardmetal coatings [2][3][4][5][6][7][8][9][10][11][12][13][14]. Most research, however, has related to the coatings sprayed from agglomerated and sintered powders, with the typical particle size ranging from 10 to 50 lm and WC grain size ranging from 0.8 to 3.5 lm [2][3][4][5][6][7].…”

“…Most research, however, has related to the coatings sprayed from agglomerated and sintered powders, with the typical particle size ranging from 10 to 50 lm and WC grain size ranging from 0.8 to 3.5 lm [2][3][4][5][6][7]. Optimization of these coatings has resulted in coating microstructures with negligible porosity, high fracture toughness and minimization of secondary carbide phases [2][3][4][5][6][7][8][9][10][15][16][17][18].…”