WC-12 Co powder was thermal sprayed on AZ91D Magnesium alloy using HVOF technique. Laser texturing substrate preparation technique was used to roughen the surface for good coating adhesion. Adhesion strength of the coating was determined using ASTM 633C adhesion strength test for thick coatings. were used to investigate coating microstructure. Coating was characterized for porosity, micro hardness and Scanning electron microscopy and X- ray diffraction techniques. The coating hence prepared, were found to achieve good adhesion strength, micro hardness and low porosity.

Direct Metal Laser Sintering (DMLS) technique is one of the technologies which is generally used to built prototypes and tooling applications. DMLS uses powder bed fusion to bond particles together by laser energy. A new powder layer is spread on top of the previous layers and the process is repeated up to required shape of part can be produced. This review paper presents development, current status and challenges of the DMLS technique with emphasises on material processed by DMLS and is aimed to understand influence of density, microstructure, micro-hardness, tensile strength and wear behaviour of built-up parts. It also highlights the process through proofs based on classical results in terms of advantages and applications.

Coating adhesion has a major effect on the performance of thermal spray coatings and is in large part determined by the chemical, physical, and mechanical properties of the substrate surface. This paper reviews some of the work that has been done to optimize the surface of different materials for thermal spraying. It covers a number of substrate preparation methods, including grit blasting, laser ablation, laser surface texturing, and dry ice blasting, and explains how different process variables affect surface roughness and bond strength.

In this study, HVOF sprayed NiCr alloy coatings on A213 TP347H boiler steel are evaluated by severe corrosion tests in a high-temperature molten salt environment. XRD and FE-SEM/EDS analysis results are presented and discussed and correlated with corrosion kinetics.

Detonation-gun thermal spray technique was used to deposit commercial available Ni-20Cr and WC-Co coatings on ASTM A213 TP347H boiler steel. The coated specimens were subjected to air environment at 900°C in laboratory furnace to determine high temperature oxidation resistance. Mass change data was recorded to formulate oxidation kinetics of both the coated specimens. The exposed specimens were assessed by field emission scanning electron microscopy and energy dispersive spectroscopy (FE-SEM/EDS) and XRD analysis. The primary focus of the study is attractive oxidation resistance of Detonation gun sprayed Ni-20 Cr coating over the WC-Co coating on the said steel in the air environment.

In this study, detonation spraying was used to deposit commercially available Ni-20Cr and WC-Co powders on SA213-T22 boiler steel. Coated and uncoated specimens were subjected to 50 thermal cycles in a molten salt boiler environment 900 °C in order to evaluate their hot corrosion behavior. Mass change measurements were made at the end of each cycle to assess corrosion kinetics and XRD and SEM/EDS were used to characterize corrosion products. An analysis of the reaction kinetics and the formation of oxide scales is provided in the paper.

HVOF thermal spray technique was used to deposit Ni-20Cr coating on a ASTM-SA213-T22 boiler steel. The corrosion behaviour was investigated for the uncoated and HVOF spray Ni-20Cr coated boiler steel in a molten salt environment (Na 2 SO 4 -60%V 2 O 5 ) at 900°C for 50 cycles. Each cycle consisted of 1 hour heating in the silicon carbide tube furnace followed by 20 min cooling in air. Mass change technique was used to approximate the kinetics of high temperature corrosion. The uncoated sample suffered intensive spallation along with a significant mass gain as compared to the coated sample. The exposed specimens were characterized by X-ray diffraction [XRD] and scanning electron microscopy/energy dispersive spectroscopy [SEM/EDS]. It was observed that HVOF sprayed Ni-20Cr coating was suitable to provide high temperature corrosion resistance to the given steel in the said(salt) environment.

In this study, HVOF thermal spray technique was used to deposit Ni-20Cr coating on a commonly used boiler steel ASTM-SA213-T22.The specimens with and without coating were subjected to cyclic oxidation testing at an elevated temperature of 900°C to ascertain usefulness of the coating for 50 cycles. Each cycle consisted of 1 hour heating in a silicon carbide tube furnace followed by 20 min cooling in air. Mass change technique was used to approximate the kinetics of oxidation. The uncoated sample suffered intensive spallation along with a significant overall mass gain. The oxidation rate was found to reduce appreciably after the deposition of the coating by 91%. The exposed specimens were characterized by X-ray diffraction [XRD] and scanning electron microscopy/energy dispersive spectroscopy [SEM/EDS]. It was observed that HVOF-sprayed Ni-20Cr coating was suitable to provide oxidation resistance to the given steel in the air environment.

The aim of this study is to investigate the role of zirconium (Zr) in HVOF coatings in order to formulate a high-temperature oxidation-resistant composition. Ni-20Cr coatings with and without 1% Zr additions were deposited on 347H boiler steel by HVOF spraying and their oxidation behavior was assessed at a temperature of 900 °C under cyclic conditions. Test specimens were also subjected to actual boiler environments to ascertain their erosion-corrosion behavior. Weight change measurements were used to determine high-temperature oxidation kinetics as well as erosion-corrosion resistance. The specimens were examined after each thermal cycle to observe physical changes and spallation in their oxide scales. It was found that the addition of Zr in the Ni-20Cr coating reduced the oxidation rate but had little effect on erosion-corrosion resistance.

A study was carried out to determine the role of HVOF-spray Ni-20Cr coatings to enhance high temperature oxidation resistance of T22 and 347H boiler steels. Ni-20Cr coatings were deposited on the boiler steels. Subsequently high temperature oxidation behavior of these coatings was investigated by laboratory tests at an elevated temperature of 9000C under cyclic conditions. These coatings were also subjected to a boiler environment at an elevated temperature of 700ºC under cyclic conditions to ascertain their erosion-corrosion behaviour. Thermogravimetric data was taken after each cycle to formulate the oxidation, as well as, erosion-corrosion kinetics. The specimens were also physically examined after each cycle to notice any macrographic physical changes, spallation tendency of their oxide scales etc. The exposed specimens were examined using scanning electron microscopy and Energy Dispersive Spectroscopy (SEM/EDS) analysis. It was observed that oxidation rate was subsequently low in the coated substrates as compare to uncoated steels. It was observed that Ni-20Cr coating on 347H boiler substrate showed the maximum oxidation resistance. Moreover, both the steels showed better resistance to erosion-corrosion in actual boiler conditions after the application of Ni-20Cr coating.