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In this study, titanium carbide (TiC) coatings were grown on the surface of a spheroidal graphite cast iron (SGI) via thermo-reactive diffusion (TRD) using powder-pack processing at 800 °C, 850 °C and 900 °C for 4 h. The TiC coatings obtained on the SGI were characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), surface profilometry, microhardness, VDI adhesion testing, wear testing, and electrochemical corrosion testing. Depending on the TRD temperature, continuous, crack-free, and smooth TiC coatings of 5–11 μm thickness and 27.96–32.45 GPa hardness were obtained on the surface. The high chemical stability, high hardness, and good adhesion strength of TiC coatings resulted in a reduced friction, high wear resistance, and superior corrosion resistance compared to the untreated sample. Delamination and oxidation assisted abrasive wear transformed into oxidation-assisted adhesive wear in the coated samples. Galvanic corrosion was dominant in untreated SGI, while homogeneous corrosion occurred in the coated samples. TiC coatings grown using TRD have the potential to be used in engineering components exposed to tribo-corrosive conditions.

WOS: 000450762200032, In the present study, the metallographic, mechanical and tribologic behaviors of AISI D2 steel specimens coated with TiC through the titanizing process were investigated. The titanizing treatment was performed at the temperatures of 900 degrees C, 1000 degrees C or 1100 degrees C for 1h, 2h or 3h using a solid-state box thermoreactive diffusion technique. In all cases, the predominant phase in the coating was TiC, but the mechanical properties of the coating varied with treatment condition. The wear resistance of the coated samples against a linear reciprocating Al2O3 ball improved as the hardness and thickness of the coating increased. The effective wear mechanism of samples that had been treated at 900 degrees C, 1000 degrees C and 1100 degrees C were severe plastic deformation, delamination and polishing type wear, respectively. The wear performance was affected by coating layer's thickness and uniformity as well as its surface hardness, elastic modulus and toughness.

Friction and wear behaviour of MoS2, boric acid, graphite and TiO2 at four different sliding speeds (1. 0, 1. 5, 2. 0, 2. 5 m/s) has been compared with dry sliding condition. MoS2 and graphite show 30 to 50% reduction in mass loss compared to other lubricants at all sliding speeds. Friction coefficient reduces with increase in sliding speeds for all the conditions. Friction coefficient of dry as well as lubricant coated samples varies from 0. 2 to 0. 55 with MoS2 showing the lowest value (0. 2). Boric acid and TiO2 coated samples show high friction coefficients at higher sliding speeds due to poor lubricity and adherence. This could also be due to sliding resistance offered by lubricant coated samples with predominant asperities interaction. MoS2 and graphite coated samples also generated lowest frictional temperature compared to other conditions. � 2012 Indian Academy of Sciences.

Coatings with a thickness of 22-32 μm were formed on an AM60B magnesium alloy by plasma electrolytic oxidation (PEO) in electrolytes containing 12.0-24.0 g/l NaAlO2 and other additives. SEM analyses of the coated samples showed that the coatings were compact with relatively low porosity. X-ray diffraction revealed that the coatings consisted of mainly MgAl 2O4 and MgO phases. The relative amount of MgAl 2O4 in the coating increased with increasing NaAlO 2 concentration. The relatively compact and thick coatings provide good corrosion protection for magnesium, as indicated by the results of potentiodynamic polarization tests. In addition, the PEO treatment also significantly improved the wear resistance of the alloy. Pin-on-disk wear tests showed that the PEO treatment reduced the wear volume loss by a factor of 10. © 2011 Elsevier B.V. All rights reserved.

The coating Cr3C2 with 50wt.% Ni20Cr deposited by high velocity oxy-fuel (HVOF) spray process was characterized in detail to investigate the effect of annealing on the solid particle erosion behaviour and understand the influence of the binder properties. Systematic characterization of the coating was carried out using electron microscopy (scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electron probe microanalysis (EPMA)), X-ray diffraction (XRD), microindentation and nanoindentation techniques. The solid particle erosion tests were done on the as-sprayed coating and coatings annealed at 400�C, 600�C and 800�C using silica erodent particles. The coefficient of restitution of the coated samples was also measured by WC ball impact tests to simulate dynamic impacts. The as-sprayed coating consisted of primary carbides and binder that was a mixture of amorphous and nanocrystalline phases. Annealing leads to recrystallisation of binder phase and precipitation of secondary carbides. The coating hardness and binder ductility change with annealing temperature. The erosion resistance improves with annealing up to 600�C. In the as-sprayed coating, the amorphous phase, inter-splat boundaries and the elastic rebound characteristics affect the erosion response. While in the case of the coating annealed at 600�C, the presence of ductile crystalline binder, fine carbide precipitates and embedment of erodent particles together improve solid particle erosion resistance. � 2010 Elsevier B.V.

Sliding counter bodies frequently undergo boundary lubrication at lubricant starved areas with dominated surface interaction under dry sliding condition. The effect of sliding speed (1.0- 2.5 m s -1) on the friction and wear performance of nitrided martensitic stainless steel in the presence of dry lubricants like boric acid and MoS 2 has been investigated, and the results are presented in this work. Under dry condition, wear loss increases and friction coefficient decreases with sliding speeds. The lubricant coated samples show minimal wear loss at all sliding speeds (2.5 m s -1). The friction coefficient shows a decreasing trend for the MoS2 coated sample, while the boric acid coated sample shows an increasing trend. This is possibly due to the temperature induced conversion of boric acid to boric oxide. The fine debris mixture formed during sliding may also pin the lamellar shearing of solid lubricants to increase friction. � 2012 Institute of Materials, Minerals and Mining.

This study investigates the effects of the deposition process and coating composition on microstructural and tribological properties of TiN-and CrN-based coating systems. Coatings were produced using various PVD-based processes-electron beam (EB), cathodic arc (CA), and plasma enhanced magnetron sputtering (PEMS). All coated samples were evaluated for their composition, microstructure, and surface morphology. Coating mechanical properties such as hardness, Young's modulus, and coefficient of friction were also studied and related to their microstructures, wear, and erosion resistances. It was found that hardness (H), Young's modulus (E), and coefficient of friction had impact on both wear and erosion rates. In particular, the H 3/E 2 ratio was inversely proportional to the specific wear rate. For erosion behavior, higher H 3/E 2 ratios relate to lower erosion rates at low impingement angles, whereas higher H 3/E 2 ratios relate to higher erosion rates at high impingement angles. © 2012 American Society of Mechanical Engineers.

Electroless nickel-phosphorus (EN) deposits with and without addition of surfactants were made on mild steel substrates. Two surfactants namely sodium dodecylsulfate (SDS) and cetyltrimethyl ammonium bromide (CTAB) were used in the study. The EN coated samples were characterised using X-ray diffraction analysis and transmission electron microscopy. The XRD pattern of all the deposits indicated the presence of crystalline and amorphous phases coexisting in the as deposited condition. Profile refinement techniques have been used to separate the crystalline nickel (111) reflection from the amorphous profile. The crystallite size of nickel was found to vary from 200 nm in the as deposited condition to 80 nm with addition of surfactant. TEM study reveals a nano crystalline structure of the deposit in as plated condition and an amorphous structure with addition of surfactants. With addition of surfactants adhesion was good. The coating thickness varied from 12.7 ?m to 32.2 ?m with addition surfactants. Copyright � 2012 Inderscience Enterprises Ltd.

The shear resistance of bitumen-coated piles in sand is studied with interface shear tests in a modified direct shear apparatus and pull-out tests on model piles. The interface shear tests are conducted to study the effect of pile material, thickness of coat, normal stress, and rate of shear on pile shear resistance. The shear resistance of bitumen-coated samples and sand is found to be independent of the roughness of the pile material. The bitumen coating reduced shear resistance by more than 90%. Shear resistance reduces with increase in the thickness of coat for a given normal stress and is found to be influenced by the rate of shear. The results of pull-out tests conducted to compare the shear behaviour of coated and uncoated model aluminium pipe piles driven in sand are also presented. The pull-out and interface shear tests show a similar response to increase in coat thickness and normal stress. The shear resistance of bitumen-coated piles is found to increase only marginally with the density of the soil. Scale effects in the model tests are also discussed.

Strong dependence of the surface-enhanced infrared spectroscopy (SEIS) on the nature of the substrate and the surface roughness were demonstrated. Surface-enhanced vibrational spectroscopy involves the study of molecules adsorbed on surfaces that can enhance the absorption and emission of electromagnetic radiation. Self-assembled monolayers (SAM), alkanethiols on gold and silver surfaces, were prepared by dipping the silver-coated samples in 1 mM solutions of the thiols in absolute ethanol for 12 hours. SEIR spectroscopy was applied successfully to the study of monolayers adsorbed on metal surfaces in reflection absorption ATR as well as in transmission geometries. The surprisingly high enhancement was observed for the IR spectra for SAM grown on Ag/Al suggesting a simple method for the preparation of SEIR active substrates. The spectra were acquired using standard detection systems in a commercial analytical spectrometer without additional preparation.