Electrodeposition and corrosion behavior of nano-structured Ni-WC and Ni-Co-WC composite coating

http://ro.ecu.edu.au/cgi/viewcontent.cgi?article=1052&context=ecuworks2013

Roles of compressive residual stress in enhancing the corrosion resistance of nano nitride composite coatings on steel

Effect Of Substrate Surface Roughness On Adhesion Of Titanium Nitride Coatings Deposited By Physical Vapour Deposition Technique

In order to improve the wear resistance of carburised M50NiL steel, the surface layer was deposited with Ti coating by magnetron sputtering and then plasma nitrided for 2 h with hollow cathode equipment. The influence of nitriding temperature (750, 800 and 850°C) on microstructure and mechanical properties of the coating were investigated. Results show that the coating of specimen 750 containing Ti-based-nitrides possesses higher nanohardness (13.769 ± 0.738 GPa) than the carburised layer (7.695 ± 0.338 GPa) and the load bearing capacity reaches 18 N due to the supporting carburised layer. The friction coefficient and wear rate of the specimen 750 decrease 23.1 and 72.2%, respectively, compared with the carburised specimen. The hardness and wear performance of the specimen 800 and 850 were underestimated by traditional test criterion because a loose and porous a′C(N) layer was formed on the surface due to sputtering effect of steel hollow cathode.

Improvement of wear resistance for carburised steel by Ti depositing and plasma nitriding

Ti–C and Ti–Si titanium compound coatings on a Ti–6Al–4V substrate are in situ synthesized by laser alloying technique to improve wear resistance of the titanium alloy. Microstructure and phase structure of the in situ synthesized coatings are investigated to understand behaviors of different kinds of titanium compound coatings. Compounds in the in situ synthesized Ti–C coating are mainly dendritic, and compounds in the in situ synthesized Ti–Si coating are block-like, lath-like and dendritic. The in situ synthesized Ti–C coating mainly contains TiC, and the in situ synthesized Ti–Si coating is chiefly composed of TiSi 2 and Ti 5 Si 3 . Microhardness of the in situ synthesized Ti–Si coating and the in situ synthesized Ti–C coating is in a range of 1500–1000 HV 0.1 and 1400–1100 HV 0.1 , respectively. Evaluation of wear resistance reveals that the in situ synthesized coatings improve the wear resistance of the Ti–6Al–4V alloy greatly. And the in situ synthesized Ti–Si coating displays better wear resistance than the in situ synthesized Ti–C coating.

Wear resistance of in situ synthesized titanium compound coatings produced by laser alloying technique

Titanium nitride (TiN) coatings were deposited on mild steel (MS) by direct current reactive magnetron sputtering. With the aim of improving the corrosion resistance of TiN, an additional nickel interlayer was brush plated on the steel substrates before TiN film formation. The phases have been identified with X-ray diffraction analysis. The hardness values of TiN layers were found to increase with the increase in thickness of the Ni interlayer. The wear track investigations of TiN layers showed that the TiN/MS system was worn out by abrasive wear mechanism while on the film with Ni interlayer is by adhesive wear. It was found that the TiN/Ni/MS stack had a weaker tendency towards corrosion and higher corrosion resistance in 3·5%NaCl than the bare MS substrate, Ni/MS and TiN/MS specimen.

K. Subramanian

Papers

Evaluation of corrosion and wear resistance titanium nitride (TiN) coated on mild steel (MS) with brush plated nickel interlayer