Superfine silicon carbide particles reinforced nickel-phosphorus(Ni-P)matrix composite coatings were prepared by electroless depositionThe morphology and structure as well as the phase transformation of the composite coatings were studied by SEM,XRD,TEM and DSCIt is shown that SiC particles co-deposited homogeneously,and the structure of Ni-P-SiC composite coatings as deposited was amorphousAfter certain heat treatment,the matrix of composite coatings crystallized into nickel crystal and nickel phosphideAt higher temperature,nickel reacted with SiC and generated nickel silicides accompanied by free carbonFinal products of Ni- P-SiC coating after completely heat treatment were consisted of Ni,Ni_3P,Ni_3Si and carbonThe finer the SiC particles in composite coating,the lower the temperature for the reaction to take place

Electroless Ni-P-SiC Composite Coatings with Superfine Particles

Hard coatings are extensively required in industry for protecting mechanical/structural parts that withstand extremely high temperature, stress, chemical corrosion, and other hostile environments. Electrical discharge coating (EDC) is an emerging surface modification technology to produce such hard coatings by using electrical discharges to coat a layer of material on workpiece surface to modify and enhance the surface characteristics or create new surface functions. This paper presents a comprehensive overview of EDC technologies for various materials, and summarises the types and key parameters of EDC processes as well as the characteristics of resulting coatings. It provides a systematic summary of the fundamentals and key features of the EDC processes, as well as its applications and future trends.

https://iopscience.iop.org/article/10.1088/2631-7990/ab7332/pdf

Surface modification and functionalization by electrical discharge coating: a comprehensive review

High-temperature corrosion of coal-fired boiler parts such as water walls and superheated tubes poses a serious threat to the efficiency of the thermal power plant. To overcome this, numbers of cor...

Performance of thermal-sprayed coatings to combat hot corrosion of coal-fired boiler tube and effect of process parameters and post-coating heat treatment on coating performance: a review

The present work investigates the hot-corrosion behavior of carbon nanotube (CNT)-reinforced chromium oxide coatings on boiler steel in a molten salt (Na2SO4-60wt%V2O5) environment at 700°C under cyclic conditions. The coatings were deposited via the high-velocity oxygen fuel process. The uncoated and coated steel samples were subjected to hot corrosion in a silicon tube furnace at 700°C for 50 cycles. The kinetics of the corrosion behavior was analyzed through mass-gain measurements after each cycle. The corrosion products were analyzed by X-ray diffraction, scanning electron microscopy, and energy-dispersive X-ray analysis techniques. The results revealed that uncoated steel suffered spallation of scale because of the formation of nonprotective Fe2O3 scale. The coated steel samples exhibited lower mass gains with better adhesiveness of oxide scale with the steel alloy until the end of exposure. The CNT-reinforced coatings were concluded to provide better corrosion resistance in the hot-corrosion environment because of the uniform dispersion of CNTs in the coating matrix and the formation of protective chromium oxides in the scale.

Hot-corrosion behavior of Cr 2 O 3 -CNT-coated ASTM-SA213-T22 steel in a molten salt environment at 700°C

Abstract The investigation into wear resistance is an up-to-date problem from the point of view of both scientific and engineering practice. In this study, HVOF coatings such as MCrAlY (CoNiCrAlY and NiCoCrAlY) and NiCrMo were deposited on AISI 310 (X15CrNi25-20) stainless steel substrates. The microstructural properties and surface morphology of the as-sprayed coatings were examined. Cavitation erosion tests were conducted using the vibratory method in accordance with the ASTM G32 standard. Sliding wear was examined with the use of a ball-on-disc tribometer, and friction coefficients were measured. The sliding and cavitation wear mechanisms were identified with the SEM-EDS method. In comparison to the NiCrMo coating, the MCrAlY coatings have lower wear resistance. The cavitation erosion resistance of the as-sprayed M(Co,Ni)CrAlY coatings is almost two times lower than that of the as-sprayed NiCrMoFeCo deposit. Moreover, the sliding wear resistance increases with increasing the nickel content as follows: CoNiCrAlY < NiCoCrAlY < NiCrMoFeCo. The mean friction coefficient of CoNiCrAlY coating equals of 0.873, which almost 50% exceed those reported for coating NiCrMoFeCo of 0.573. The as-sprayed NiCrMoFeCo coating presents superior sliding wear and cavitation erosion resistance to the as-sprayed MCrAlY (CoNiCrAlY and NiCoCrAlY) coatings.

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Cavitation Erosion and Sliding Wear of MCrAlY and NiCrMo Coatings Deposited by HVOF Thermal Spraying

Study of High-Temperature Corrosion Behavior of D-Gun Spray Coatings on ASTM-SA213, T-11 Steel in Molten Salt Environment

The present paper deals with the investigation of microstructure and high-temperature hot corrosion behavior of high-velocity oxy fuel (HVOF)-produced coatings. Two powder coating compositions, namely, Ni22Cr10Al1Y alloy powder and Ni22Cr10Al1Y (80wt%; microsized)-silicon carbide (SiC) (20wt%; nano (N)) powder, were deposited on a T-22 boiler tube steel. The hot corrosion behavior of bare and coated steels was tested at 900°C for 50 cycles in Na2SO4-60wt%V2O5 molten-salt environment. The kinetics of corrosion was established with weight change measurements after each cycle. The microporosity and microhardness of the as-coated samples have been reported. The X-ray diffraction, field emission-scanning electron microscopy/energy dispersive spectroscopy, and X-ray mapping characterization techniques have been utilized for structural analysis of the as-coated and hot-corroded samples. The results showed that both coatings were deposited with a porosity less than 2%. Both coated samples revealed the development of harder surfaces than the substrate. During hot corrosion testing, the bare T22 steel showed an accelerated corrosion in comparison with its coated counterparts. The HVOF-sprayed coatings were befitted effectively by maintaining their adherence during testing. The Ni22Cr10Al1Y-20wt%SiC (N) composite coating was more effective than the Ni-22Cr-10Al-1Y coating against corrosion in the high-temperature fluxing process.

Microstructural analysis and hot corrosion behavior of HVOF-sprayed Ni–22Cr–10Al–1Y and Ni–22Cr–10Al–1Y–SiC (N) coatings on ASTM-SA213-T22 steel

Experimental studies on material removal rate, tool wear rate and surface properties of machined surface by powder mixed electric discharge machining

Hot corrosion behavior of HVOF-sprayed carbide based composite coatings for boiler steel in Na2SO4–60 % V2O5 environment at 900 °C under cyclic conditions

https://iopscience.iop.org/article/10.1088/2053-1591/ab1f96/pdf

Gurmail Singh

Papers

Study of High-Temperature Corrosion Behavior of D-Gun Spray Coatings on ASTM-SA213, T-11 Steel in Molten Salt Environment

Microstructural analysis and hot corrosion behavior of HVOF-sprayed Ni–22Cr–10Al–1Y and Ni–22Cr–10Al–1Y–SiC (N) coatings on ASTM-SA213-T22 steel

Experimental studies on material removal rate, tool wear rate and surface properties of machined surface by powder mixed electric discharge machining

Hot corrosion behavior of HVOF-sprayed carbide based composite coatings for boiler steel in Na2SO4–60 % V2O5 environment at 900 °C under cyclic conditions

High temperature oxidation behaviour and characterization of NiCrAlY-B4C coatings deposited by HVOF