Microhardness Improvement of Ni-W/SiC Composite Coatings by High Frequency Induction Heat Treatment

Abstract

Electrodeposited Ni-W alloy coating is considered as one of the most suitable candidate to replace the environmentally hazardous hexavalent hard chromium coatings. However, it is necessary to carry out heat-treatment at a high temperature to improve its microhardness and refine its grain. In the present work, an alternative high frequency induction heat-treatment (HFI-HT) technology was used to improve surface microhardness of Ni-W/SiC composite coatings, which were electrodeposited from an ammonium-citrate bath, containing suspended green SiC particles. Transformation of amorphous to crystalline structure can be observed after HFI-HT. The precipitation of a Ni 6 W 6 C phase rather than a Ni 4 W phase occurs by prolonging induction time to 64 s at a power density of 21 W mm −2 or turning power density up to 42 W mm −2 for 4 s. While the two phases of Ni 6 W 6 C and Ni 4 W can be precipitated at 900°C. The microhardness of Ni-W/SiC composite coatings can be improved up to 1100 HV with HFI-HT at 21 W mm −2 for 8 s, which is comparable to that of hard chrome coatings.

Effect of Al2O3 Nanoparticles and Heat Treatment on the Wear Resistance of Electrodeposited Ni-W/Al2O3 Composite Coatings

“…Before electrodeposition, the substrate was polished by different grades of emery papers, activated by immersing in HCl solution (15%) for 15 s and then cleaned with de-ionized water. The electrodeposition parameters and the composition of electrolytes used in this paper are similar to many literature ( Ref 1,4,16,21) and listed in Table 1. The trisodium citrate was applied as complexing agent, and no surfactants were added into the electrolyte.…”

The Effect of Heat Treatment on Phase Structure and Mechanical and Corrosion Resistance Properties of High Tungsten Ni-W Alloy Coating

“…WC has been synthesized in situ by laser cladding, improving the properties of Ni coating and Co alloy coating [10,11]. Su et al [12] found that the high-frequency induction heat treatment of Ni-W alloy coating yielded Ni 4 W and Ni 6 W 6 C precipitates, achieving a 1100 Hv coat hardness. Lee et al found that Ni 4 W and Ni 6 W 6 C were obtained by irradiating Ni-W alloy at room temperature and annealing at 850 • C [13].…”

Preparation and Properties of Ni–W Composite Coatings Reinforced by Graphene Nanoplatelets

“…The Ni–W co‐deposition technology was developed to resolve this dilemma. It was found that the co‐deposition of various micro/nanoparticles such as Si 3 N 4 , [ 10 ] Al 2 O 3 , [ 11 ] SiC, [ 12,13 ] ZrO 2 , [ 14–18 ] TiN, [ 19–21 ] TiB 2 , [ 22 ] diamond, [ 23 ] and multi‐walled carbon nanotubes (MWCNTs) [ 24,25 ] with the Ni–W alloy matrix can significantly enhance the mechanical properties and the corrosion resistance of the coating.…”