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Due to the harsh underground environment in coal mining, the surface of hydraulic support columns corrodes severely, resulting in significant economic losses. Therefore, a highly corrosion-resistant coatings is needed to extend the service life of the columns.

This study aims to compare the corrosion resistance of ST-Cr₃C₂-NiCr (sealed treatment Cr₃C₂-NiCr) coatings with industrially applied chromium plating. The corrosion failure mechanism of the coatings was investigated.

The results demonstrated that the ST-Cr₃C₂-NiCr coatings exhibited excellent corrosion resistance. After sealing treatment, the corrosion potential of Cr₃C₂-NiCr coatings was −0.215 V, and the corrosion current density of Cr₃C₂-NiCr coatings was lower than that of the plated parts.

ST-Cr₃C₂-NiCr coatings prepared by supersonic atmospheric plasma spraying could provide excellent corrosion resistance in the coal industry.

The low porosity and the presence of the NiCr phase were crucial factors contributing to the preferable corrosion resistance exhibited by the ST-Cr₃C₂-NiCr coatings. The corrosive process of the coatings involved layer-by-layer delamination of surface oxide film, sub-surface pitting, formation and degradation of sub-surface passive film, as well as severe block-like delamination.

45 steel is a common material for the manufacture of various components such as shafts or gears. However, its poor surface properties often limit its applications. The purpose of this paper is to find a way to enhance the surface performance of 45 steel, which is expected to improve the wear resistance of 45 steel.

Double glow plasma surface metallurgy technique was used to prepare hafnium carbide (HfC) coatings on the surface of the 45 steel with two preparation process; one is to diffuse two elements together, while the other is to diffuse step by step. The scanning electronic microscopy and the X-ray diffraction were used to analyze the morphology and phase of the HfC coatings. And then the wear tests were carried out for this coating.

Coating diffused step by step shows better performance; it has a 15-µm alloyed layer which is uniform and dense and its hardness can reach up to 1326.5 Vickers-hardness (HV). While the coating fabricated by diffusing elements together owns a 10-µm alloyed layer and its hardness is 1204.1 HV. According to the wear test results, both coatings have a protective effect on the substrate and the coating prepared by step-by-step diffusion process has less wear volume, indicating that it possesses better friction reduction.

A new method which diffuses elements together was successfully used to prepare compound HfC coating, which can reduce the cost of coating preparation and improve the efficiency of coating preparation.

In the present study, Al₂O₃ coatings were deposited on stainless steel AISI-304 material by using atmospheric plasma spraying technique to combat high temperature solid particle erosion. The present aims at the performance analysis of Al₂O₃ coatings at high temperature conditions.

The erosion studies were carried out at a temperature of 400°C by using a hot air-jet erosion tester for 30° and 90° impingement angles. The possible erosion mechanisms were analyzed from scanning electron microscope (SEM) micrographs. Surface characterization of the powder and coatings were conducted by using an X-ray diffractometer, SEM, equipped with an energy dispersive X-ray analyzer. The porosity, surface roughness and micro-hardness of the as-sprayed coating were measured. This paper discusses outcomes of the commonly used thermal spray technology, namely, the plasma spray method to provide protection against erosion.

The plasma spraying method was used to successfully deposit Al₂O₃ coating onto the AISI 304 substrate material. Detailed microstructural and mechanical investigations were carried out to understand the structure-property correlations. Major findings were summarized as under: the erosive wear test results indicate that the plasma sprayed coating could protect the substrate at both 30° and 90° impact angles. The coating shows better resistance at an impact angle of 30° compared with 90°, which is related to the pinning and shielding effect of the alumina particle. The major erosion wear mechanisms of Al₂O₃ coating were micro-cutting, micro-ploughing, splat removal and detachment of Al₂O₃ hard particles.

In the current study, the authors have followed the standard testing method of hot air jet erosion test as per American society for testing of materials G76-02 standard and reported the erosion behavior of the eroded samples. The coating was not removed at all even after the erosion test duration i.e. 10 min. The erosion test was continued till 3 h to understand the evolution of coatings and the same has been explained in the erosion mechanism. The outcome of the present study may be used to minimize the high temperature erosion of AISI-304 substrate.

This paper aims to verify weather atmospheric plasma spray (APS) in situ remelting posttreatment is effective for densifying the porous FeCoCrMoCBY amorphous alloy (FAA) coating and improving the antiabrasion and anticorrosion performances or not.

APS was used to deposit and in situ densify FAA coating on the 40Cr substrate. Scanning electron microscope, X-ray diffractometer, energy dispersive spectroscopy, neutral salt spray, hardness and wear behavior test were used to evaluate the densifying effects.

APS remelting technology can effectively improve the hardness of the coating by reducing the porosity. After remelting at 30 kW power, the hardness of the coating increased by about 260 HV0.2 and the porosity decreased to 2.78%. The amorphous content of the coating is 93.9%, which is about 3.5% lower than original powders. The electrochemical impedance spectrum and neutral salt spray test results show that APS remelting can reduce the corrosion rate by about 62.7%.

APS remelting method is firstly proposed in this work to replace laser remelting or laser cladding methods. APS remelting method can effectively improve the corrosion and abrasion resistance of the FAA coating by increasing the densification with much low recrystallization, which is big progress for application of FAA coatings.

Application of cold spray technology may exhibit significant benefits for the additive manufacturing process, particularly for producing intricate objects. To ascertain the feasibility of such an application, this paper aims to present a numerical investigation of the effect of scaling down a convergent-divergent (de Laval) nozzle, which is typically used in the cold spray industry, on the compressible flow parameters and thermal characteristics.

The Navier–Stokes equations and energy equation governing compressible flow are numerically solved using a finite volume method with a coupled solver. The conjugate heat transfer technique is used to couple fluid and solid heat transfer domains and predict the local heat transfer coefficient between the solid and fluid. The use of various RANS turbulence models has also been investigated to quantify the effect of the turbulence model on the simulation.

The numerical results reveal that the flow and thermal characteristics are altered as the convergent-divergent nozzle is scaled down. The static pressure and temperature profiles at any section in the nozzle are shifted toward higher values, while the Mach number profile at any section in the nozzle is shifted toward a lower Mach number. The turbulent kinetic energy at the nozzle exit increases with the scaling down of the nozzle geometry. This study also provides convincing evidence that the adiabatic approach is still suitable even though the temperature of the nozzle wall is extremely high, as required for industrial application. Results indicate that it is feasible to use the available capabilities of the cold spray technology for additive manufacturing after scaling down the nozzle.

The idea of adopting cold spray technology for additive manufacturing is new and innovative. To develop this idea into a viable commercial product, a thorough understanding of the flow physics within a cold spray nozzle is required. The simulation results discussed in this paper demonstrate the effect that scaling down of a convergent-divergent nozzle has on the flow characteristics in the nozzle.

This paper seeks to summarise the results of available research on the use of high velocity oxy‐fuel (HVOF) thermal‐spray technique to provide protection against high temperature corrosion and erosion‐corrosion of materials.

This paper describes one of the recent thermal‐spray processes, namely HVOF thermal‐spray technology and presents a survey of the studies on the use of this technique to provide protection against corrosion and erosion‐corrosion of high temperature alloys, with a special emphasis on boiler steels.

High temperature corrosion and erosion‐corrosion are serious problems observed in steam‐powered electricity generation plants, gas turbines, internal combustion engines, fluidized bed combustors, industrial waste incinerators and recovery boilers in paper and pulp industries. These problems can be prevented by changing the material or altering the environment, or by separating the component surface from the environment. Corrosion prevention by the use of coatings for separating materials from the environment is gaining importance in surface engineering. Amongst various surface modifying techniques, thermal spraying has developed relatively rapidly due to the use of advanced coating formulations and improvements in coating application technology. One of the variants of thermal spraying, namely HVOF has gained popularity in recent times due to its flexibility for in‐situ applications and superior coating properties.

This review covers mainly information that has been reported previously in the open literature, international journals and some well‐known textbooks.

The paper presents a concise summary of information for scientists and academics, planning to start their research work in the area of surface engineering.

This paper fulfils an identified information/resources need and offers practical help to an individual starting out on a career in the area of surface engineering for erosion‐corrosion and wear.

Discusses developments in coatings using high velocity oxyfuel (HVOF). Covers the basic process, comparisons with other thermal spraying processes and optimization of performance. Discusses industrial applications and new developments in the technology.

This paper aims to consolidate the results of various researchers focusing the different applications, so that this paper could become the torch bearer for the futuristic researchers working in the domain of cold gas dynamics spray coating.

A study on the cold spray coating is presented by summarizing the data present in literature. Important factors such as coating temperature, pressure, coating thickness, particle size, which affect the erosion-corrosion (E-C) resistance, physical and mechanical properties of boiler steel are stated. This paper also addresses the use of cold spray coating and compares it with other different thermal spray processes.

From the literature review, it was noticed that cold spray technology is best as compare to other thermal spray processes to reduce porosity, increase hardness, adhesion strength and retention in properties of feedstock powders.

Cold spray coating technology has a great potential in almost every field especially in restoration of surfaces, generation of complex surface, biomedical application, resist hot corrosion, wear, oxidation and erosion corrosion.

The purpose of this paper is to improve the tribological properties of aluminum cylinder liner. Higher martensite contents were closely related to the higher hardness and excellent wear resistance of Fe-based coatings. Furthermore, the grain size of the Fe-based coating was approximately 40 nm, which provides an excellent fine grain strengthening effect.

To improve the tribological properties of aluminum cylinder liners, a Fe-based martensite coating was prepared by internal plasma spraying technology, whose microstructure and tribological properties were then investigated.

Sprayed Fe-based coating possessed a low contact angle and strong adhesion with lubricating oil. In a simulated engine condition, Fe-based coating exhibited a decreased friction coefficient and increased wear resistance under oil lubrication, which was dominated by a stronger adhesive force with lubricating oil, higher martensite contents on the worn surface, higher hardness and higher H/E value than those of the reference HT 200 and Al-19Si cylinder material.

Nanostructure Fe-based martensite coating was sprayed on an aluminum cylinder liner, which demonstrated remarkable advantages over the reference cylinder material.

EVEN the technical press is inclined to devote more space to developments in aircraft and their component parts than to the metals and materials employed in their construction. In this article the writer proposes to survey the entire field of aircraft metals developed of recent years.