Low-pressure Cold Spray Research Articles

Characterization and Sliding Wear Behavior of Low-Pressure Cold-Spray Al-Al2O3 and Al-Al2O3/TiN Composite Coatings

Low-pressure cold-spray (LPCS) aluminum is widely used for coating depositions in various engineering applications but is limited by its low hardness and poor wear resistance. To improve these properties, ceramic particles are added to form metallic matrix composites (MMCs). High-pressure processes can achieve effective MMC coatings but are costly and energy intensive. LPCS has been studied to develop an Al-based MMC at a lower cost. To ensure the adaptation of developed LPCS coating in engineering applications, the behavior of the coating under certain loads needs to be established. This study investigates the sliding wear behavior, friction characteristics, hardness, and microstructure of Al-Al2O3 and Al-Al2O3/TiN composite coatings deposited using LPCS at 1 MPa and 450 °C. The effect of adding 25 wt% TiN to the Al-Al2O3 composite was explored. Although the addition of TiN did not significantly enhance the hardness of the coating, SEM analysis revealed notable differences in wear behavior between the two coatings. The Al-Al2O3/TiN composite exhibited better wear resistance, which was attributed to the reduced formation of powdery wear debris and improved crack suppression. These findings highlight the potential of TiN reinforcement to enhance the tribological performance of LPCS aluminum-based coatings, offering a promising solution for improving wear resistance in engineering applications.

Subsurface Weave Pattern Influences on Polymer Cold Spray Deposits onto Woven Fiber-Reinforced Composites

AbstractThe polymer cold spray (CS) process has recently been demonstrated as a promising coating and repair technique for fiber-reinforced polymer composites (FRPs). However, a noticeable variation in coating thickness (herein referred to as checkerboard pattern) often occurs in the initial pass of low-pressure CS deposition. The checkerboard pattern occurs due to the periodic variations in matrix thickness and volume above the subsurface fiber weave pattern. When the initial pass exhibits the so-called checkerboard pattern, the CS deposition for subsequent passes may be negatively affected in terms of deposition efficiency, porosity, adhesion, surface roughness, and thickness consistency. The present work compares results of both numerical simulations and experimental studies performed to reveal the governing mechanisms for and elimination of checkerboarding. Single particle impact numerical simulations are conducted to observe thermomechanical behavior of particles during CS impact on the FRP surface at different regions of the composite material. Complementary experimental CS studies of exemplar powders onto FRPs with various surface interlayer thicknesses are also presented and discussed. Experimental analyses of deposits include microstructural observations to compare against the simulations while also providing practical strategies for the elimination of checkerboarding effects. It is demonstrated that the thickness and volume of the matrix region underneath the impact area are the main contributing factors that govern the CS deposition variations on CFRP substrates. As such, increasing the surface epoxy layer thickness beyond a critical value can reduce the effect of substrate stiffness effects imposed by the subsurface fiber tows, thereby effectively eliminating the checkerboard patterns.

On the Role of Substrate in Hydroxyapatite Coating Formation by Cold Spray

The deposition of agglomerated hydroxyapatite (HAp) powders by low-pressure cold spray has been a topic of interest in recent years. Key parameters influencing the deposition of HAp powders include particle morphology and impact kinetic energy. This work examines the deposition of HAp powders on various metal surfaces to assess the impact of substrate properties on the formation of HAp deposits via cold spray. The substrates studied here encompass metals with varying hardness and thermal conductivities, including Al6061, Inconel alloy 625, AISI 316 stainless steel, H13 tool steel, Ti6Al4V, and AZ31 alloy. Single-track experiments offer insights into the initial interactions between HAp particles and different substrate surfaces. In this study, the results indicate that the ductility of the substrate may enhance HAp particle deposition only at the first deposition stages where substrate/particle interaction is the most critical factor for deposition. Features on the substrate associated with the first deposition sprayed layer include localized substrate deformation and the formation of clusters of HAp agglomerates, which aid in HAp deposition. Furthermore, after multiple spraying passes on the various metallic surfaces, deposition efficiency was significantly reduced when the build-up process of HAp coatings shifted from ceramic/metal to ceramic/ceramic interactions. Overall, this study achieved agglomerated HAp deposits with high deposition efficiencies (30–60%) through single-track experiments and resulted in the preparation of HAp coatings on various substrates with thickness values ranging from 24 to 53 µm. These coatings exhibited bioactive behavior in simulated body fluid.

Improving bond strength and deposition efficiency of ceramic coatings via low pressure cold spraying: A study on hydroxyapatite coatings with Cu-Zn blends

This study presents Low Pressure Cold Spraying (LPCS) method for ceramic coatings, aimed at enhancing efficiency and elucidating bonding mechanisms. It focuses on the deposition of ceramic coatings using LPCS, with hydroxyapatite (HA) on 316L stainless steel (SS) as an illustrative example. Despite the advantages of LPCS, retaining HA particles has proven challenging, resulting in thin coatings (11.09 ± 2.56 μm) with low bonding strength (1.80 ± 0.19 MPa). To address this issue, a composite coating strategy was developed by blending 20 wt% Cu and Zn powder with 80 wt% HA. This approach significantly improved coating properties, achieving enhanced bonding strength (33.70 ± 1.13 MPa), deposition efficiency (27 %), and hardness (136.30 ± 2.45 HV) compared to pure Cu-Zn coatings. Numerical simulations were conducted to interpret these experimental results, indicating that blending metal with HA improves deposition efficiency, bonding strength, and hardness. In HA coatings, particles fragment into submicron grains and embed into the substrate through mechanical interlocking (MI), with shockwave-induced bonding strengthening subsequent layers. For Cu-Zn coatings, bonding occurs through MI and adiabatic shear instability (ASI). In HA-Cu-Zn coatings, high-velocity HA particles and Zn particles enhance bonding further through in-situ tamping.

Combinatorial synthesis of AlNi alloys by low-pressure cold spray deposition and post-laser alloying process

Aluminum-Nickel (AlNi) alloys are of great interest due to their exceptional high-temperature wear and corrosion resistance, making them valuable in transport, energy, and materials processing applications. However, challenges in the production and shaping of these alloys, particularly as thick coatings, remain significant. This study introduces an innovative method for the high-throughput synthesis of AlNi coatings, utilizing a two-step process: low-pressure cold spray deposition followed by laser surface alloying. The combination of these two techniques not only improves the synthesis process but also opens avenues for exploring new material compositions with specific application requirements. This approach holds significant potential for accelerating the development and optimization of advanced coatings and multiphase compounds in applications such as repair and additive manufacturing.Aluminum and nickel powders were co-sprayed to create coatings with controlled compositions ranging from 50Al50Ni to 10Al90Ni (wt%). Subsequent laser treatment induced in-situ alloying and homogenization, resulting in dense, uniform AlNi coatings. The microstructure and chemical composition were characterized using Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS), while X-ray Diffraction (XRD) identified the formation of various phases, including Al3Ni and AlNi3 phases. The process demonstrated effective alloying and microstructural homogeneity, with residual alumina present at the surface. Despite the presence of some microstructural defects, such as cracking, this method provides a robust foundation for further refinement and opens new possibilities for tailoring alloy properties through combinatorial cold spray and laser alloying techniques.

Effect of plastic deformation of particle and substrate on metallurgical bonding during cold spraying

The metallurgical bonding of cold spraying is investigated from the perspective of plastic deformation. The individual Al particle was deposited on the surface of Ni substrate by low-pressure cold spraying technology. Direct observation of the Al/Ni interface from the cross-sectional morphology shows that metallurgical bonding occurs only at the partial Al/Ni interface. The finite element simulation considering the presence of oxide layer confirms that the metallurgical bonding is located in front of the maximum plastic deformation area. In the maximum plastic deformation area, the relative displacement between Al particle and Ni substrate exists from the beginning of contact to the end of deposition, which makes the metallurgical bonding discontinuous and gradually disappear.

Manufacturing and cold spraying of hybrid composites — A path for metallizing thermoset matrix composites

This study aims to realize and metallize the hybrid thermoset-thermoplastic fiber reinforced composites for aerospace applications. Two variations in the manufacturing route including cocuring and hybrid interlayer were adopted for realizing the RTM6-PEI-CF composite. Low pressure cold spray metallization technique is applied by varying the processing parameters stand-off distance and traverse speed. Microstructural analysis and mechanical tests (roughness check, nanoindentation tests) were performed on sprayed composites. Overall, manufacturing routes affected the inherent structure of the composite and subsequent coating quality. Mechanical interlocking induced close contact of PEI-aluminum (Al) particles characterized into uniform coating with surface morphology variation shown in cocured composites. Coating adhesion strength increment up to 18 MPa was noted by using the PEI-carbon fiber (CF) semi-preg in manufacturing. The tomography scan highlighted the structural integrity of the manufactured and coated composites, revealing coating-thermoplastic contact, interphase, and porosity in the inter-tow fiber region. An increase in the traverse speed to 2 mm/s reduced the electrical conductivity and adhesion strength of the coating with the hybrid composite. Within the limits of this investigation, opting for lower stand-off distance and traverse speed (here, 10 mm and 1 mm/s) reflected in improved adhesion and approximately 1.5 mm coating thickness.

Repairing Al7075 surface using cold spray technology with different metal/ceramic powders

Cold spray process is essentially a coating technique as well as used in repair applications. This method is a low-temperature solid-state process. In this study, the damaged surface of Al7075 was repaired by low pressure cold spray method with Ni-Zn-Al2O3, Al-Zn-Al2O3, Al-Al2O3, Ni-Al2O3, and Zn-Al2O3 metal/ceramic feedstock powders. Microstructure examination, microhardness measurements, tribological experiments, and tensile tests were conducted on the repaired samples and compared with Al7075. The repaired regions exhibited a composite microstructure characterized by the presence of Al2O3 ceramic particles with high hardness dispersed within a metal matrix composed of Al, Ni, Zn, Ni-Zn, and Al-Zn. This composite structure was attributed to the interlocking mechanism of cold spray. The highest hardness value was measured in the repaired area using Ni-Al2O3, which is approximately 1.28 times higher than that of Al7075 alloy. According to the dry sliding test, the wear performance of all repaired specimens was superior to that of Al7075. The wear resistance of samples repaired with Ni-Al2O3 and Ni-Zn-Al2O3 increased approximately 7.1 and 5.8 times, respectively, compared to Al7075. The specimens repaired with Ni-Zn-Al2O3 feedstock powder showed the most similar results in tensile and yield strength values to Al7075 to the tensile test.

Erosion behaviour of low-pressure cold-sprayed Ni coatings for concentrating solar power receivers

Nickel-based coatings provide outstanding wear and erosion resistance making them particularly suitable for several applications, from aerospace and naval to automotive, energy, and electrical. Cold spray (CS) is encountering a growing interest as a promising technology to deposit thick and dense coatings for components used in energy power generation systems, such as the concentrating solar power (CSP) plants. In this article, nickel coating was deposited onto steel substrates by using a low-pressure CS. The erosion behaviour of the coating was evaluated by a solid particle impact test at two different impact angles. The coating erosion rate was 10 × 10−4 at a 60° impact angle, showing a combination of ploughing and cutting mechanisms.

Mixed-Material Feedstocks for Cold Spray Additive Manufacturing of Metal–Polymer Composites

High-performance polymers such as poly(ether ether ketone) (PEEK) are appealing as composite components for a wide variety of industrial and medical applications due to their excellent thermomechanical properties. However, conventional PEEK metallization methods can often lead to poor quality control, low deposition rate, and high cost. Cold spray is a promising potential alternative to produce polymer–metal composites rapidly and inexpensively due to its relatively mild operating conditions and high throughput. In this study, we investigated the deposition characteristics of metal–polymer composite feedstock, composed of PEEK powder and copper flake in varying ratios, onto a PEEK substrate. Copper-PEEK powder blends were prepared by both hand-mixing and cryogenic milling (cryomilling), which predominantly creates composite particles with micron-scale copper domains coating PEEK particle surfaces. This process non-monotonically affects the relative dominance and length scales of the multiple contributing deposition mechanisms present in mixed-material cold spray. In low-pressure cold spray, deposits showed significant changes in deposition efficiency and composition as a result of milling, with improvements in these characteristics most dramatic at lower Cu fractions. Deposits of a cryomilled blend of nominally 30 vol.% copper in PEEK exhibited minimal porosity under scanning electron microscopy, complete retention of powder composition, and the highest deposition efficiency among all samples tested. Notably, neither neat PEEK nor neat Cu meaningfully deposited at the same mild conditions as this 30 vol.% Cu blend, indicating a synergistic departure from linear mixing rules driven by the relative balance of local deposition interactions (e.g., hard–soft, soft–soft, etc.). Intentional powder and process design toward optimizing this balance may facilitate cold spray metallization applications.

Polymer Metallization by Cold Spray Deposition of Polyamide-Copper Composite Coatings

Cold spray metallization of polymers is a promising surface engineering technique that enables the deposition of metal coatings onto polymer substrates at low process temperatures, resulting in improved surface properties, thus enhanced functionality of the polymeric material. However, deposition of well-adhering metallic coatings without causing surface damage to the polymer substrate is still a challenge. In this work, copper-polyamide composite coatings with different copper concentrations between 30 and 75 vol.% in the starting powders were deposited on polyamide substrates using a low-pressure cold spray system with two nozzle geometries of short and long diverging sections. The spray parameters were first developed for the deposition of polyamide powder (at gas temperature of 260 °C and gas pressures ranging from 0.41 to 1.37 MPa), and then used to spray the composite powder mixtures where the polyamide particles were acting as a binder for copper particles. Inflight and impact particle characteristics (velocity and temperature) of the polyamide powder were simulated to better understand the deposition properties. Considering that the selected conditions were suboptimal for the deposition of copper particles, no surface damage was caused as no penetration of the copper particles into the polymer substrate occurred. The results show that increasing the copper content in the powder mixtures significantly improved the resulting coating uniformity and the retained copper content. In addition, the coating deposited by spraying the powder mixture with a higher copper content of 75 vol.% and using the longer nozzle yielded the highest cohesion strength. To further improve coatings cohesion, two post-spray processing methods of furnace heating and hot pressing were used, and the effect of each process on coatings properties was investigated.Please confirm if the author names are presented accurately and in the correct sequence (given name, middle name/initial, family name). Given name: [Kintak Raymond] Last name [Yu]. Also, kindly confirm the details in the metadata are correct.The author names are now correct: Kintak Raymond given name and Yu last nameAll other details are corrects

Metallisation of additive manufactured polyamide 12 by low pressure cold spray

Cold Spray is a solid deposition process that can expand the field of application of polymeric materials thanks to the build-up of a metallic coating that improves their electrical properties and the wear resistance, among others. The novelty of the Cold Spray deposition on polymers has as drawback the lack of processing models that allow to choose the manufacturing parameters and forecast the coatings and substrates properties. In this work, the influence of the processing parameters for Aluminium-Zinc coating build-up via Low Pressure Cold Spray on polyamide 12 additively manufactured via Fused Filament Fabrication was investigated. Several sets of processing parameters combinations were systematically modified to establish the deposition window, leading to a final set that allowed to determine the physical, microstructural, and mechanical properties of the coatings, and the physical and thermal properties of the polymeric substrate. For the fixed gas pressure of 0.45 MPa and gas temperature of 500 °C, the scanning speed and the powder mass flow rate had a strong influence. Thick coatings (around 850 μm in size) were achieved at high powder mass flow rate (26 g/min) at the expense of low bond strength (between 1 and 3 MPa). The surface roughness acquired the highest values in those samples where erosion took place, occurring this phenomenon at small standoff distances and low powder mass flow rate, and no finding any relationship with the transverse gun speed. The generation of an interface layer of mixed metallic particles polymeric substrate plays a key role in the subsequent metallic coating growth, with thicknesses that ranged from 30 μm to 200 μm. In the substrate, the crystallinity degree of the polyamide underneath the coating increased, evidence of a heat affected zone where temperatures around the crystallisation temperature were reached, that also promoted stretching of the polymeric substrate due to dilatational phenomena. All this accompanied of an overall decrease in the thickness of the PA12 coupon after coating build up deposition with the high powder mass flow rate. This evidence indicates that a large plastic deformation of the polymeric substrate at the most energetic combination of processing parameters took place.

Microstructure and corrosion properties of Cu coatings deposited via laser-assisted low-pressure cold spray

Cu coatings were prepared via the laser-assisted low-pressure cold spray (LPCS) method to study the effect of laser irradiation on microstructure and corrosion behaviors of the coatings. The results reveal that the laser-assisted LPCS-Cu coatings are denser and have better coating−substrate interfacial bonding as compared to LPCS-Cu coating. Laser irradiation improves the overall plastic deformation of deposited particles, resulting in uniform grain refinement of Cu particles. Therefore, the laser-assisted LPCS-Cu coatings show more uniform microstructure and smaller grain size. The results of electrochemical tests demonstrated that laser-assisted LPCS-Cu coatings have higher corrosion potential, lower corrosion current and corrosion rate than the LPCS-Cu coating in 3.5 wt.% NaCl solution. The main reason is that laser irradiation improves the coating density and intimate bonding between particles, and a continuous and dense corrosion product film composed of CuCl and Cu2O is formed on the surface of the laser-assisted LPCS-Cu coating to block the erosion of the corrosive solution.

Denseness and Adhesion of Low-Pressure Cold Spray Coating to Corroded Steel Bridges

Denseness and Adhesion of Low-Pressure Cold Spray Coating to Corroded Steel Bridges

Optimal Design of a Cold Spray Nozzle for Inner Wall Coating Fabrication by Combining CFD Simulation and Neural Networks

AbstractRecently, the low-pressure cold spray (LPCS) technique has been used to fabricate superhydrophobic polymer coatings on metallic substrates, suggesting a significant potential in engineering applications. This study aims to design a spiral LPCS nozzle to coat the pipe’s inner wall with superhydrophobic polymer. The design goal is to achieve the maximum particle velocity in a confined (limited) space, assuming that the powder can enter the feeding tube through the Venturi effect. Achieving these two goals simultaneously using only computational fluid dynamics (CFD) simulation is challenging. Therefore, the CFD simulation was combined with the neural network (NN) method to design the new spiral nozzle. During training, the effects of the NN models and algorithms were investigated. The results showed that the feedforwardnet model combined with the trainbr or trainlm algorithm (from MATLAB 2016b software), presented a minimal error for particle velocity or gas flux prediction, respectively. The trained NN correlates the nozzle parameters (i.e., mean coil diameter, spring lift angle, and expansion ratio) and its performances (i.e., particle velocity and gas flux in the powder feeding tube). As a result, the optimal spiral nozzle was determined based on the design goal of maximum particle velocity and suitable gas flux in the powder feeding tube. Furthermore, the effect of each nozzle parameter on the particle velocity and gas flux in the powder feeding tube was analyzed. The cold spray experiment confirmed that the designed spiral nozzle could fabricate Perfluoroalkoxy alkane (PFA) coatings.

Enhanced wear resistance of AlCoCrFeMo high entropy coatings (HECs) through various thermal spray techniques

The remarkable mechanical and wear properties of high entropy alloys (HEAs) have opened up exciting possibilities for their use in aerospace applications. This study explores the potential of AlCoCrFeMo high entropy coatings (HECs) fabricated using three thermal spray techniques, namely low-pressure cold spray (LPCS), flame spray (FS), and high-velocity oxy fuel spray (HVOF) as wear resistant surfaces. The coatings were investigated in terms of their microstructures, phases, mechanical properties, and sliding wear characteristics from room temperature up to 350 °C. Ex-situ characterization was performed using XRD for phase analysis and SEM-EDS for cross-sectional microscopy and phase compositions of the coatings. All three coatings exhibited a typical lamellar structure with the formation of BCC solid solution phase and variations in porosity and oxide content. The HVOF sprayed coatings showed higher hardness values compared to the FS and LPCS coatings, which can be attributed to their fine splats microstructure, lower porosity, and oxide inclusions compared to the other two coatings. In terms of tribological performance, the LPCS coatings exhibited overall lower frictional coefficient than the FS and HVOF coatings at both tested temperatures. However, the HVOF coatings exhibited relatively lower wear rates, correlating well with observations from ex-situ analysis, highlighting lower material transfer and decreased formation of debris particles compared to LPCS and FS coatings. These findings suggest that the HEA materials have great potential as next-generation tribological interfaces under high-temperature wear conditions, emphasizing the importance of designing materials with improved microstructural features.

Optimization of cold spray process parameters to maximize adhesion and deposition efficiency of Ni+Al2O3 coatings

The paper considers the conducted study of the complex effect of low-pressure cold spraying parameters, namely the nozzle inlet temperature, stand-off distance, and powder feed rate on the adhesion and deposition efficiency of coatings from a Ni+Al2O3 powder on VT3-1 titanium alloy substrate. Based on predetermined information, the main levels and intervals of factor variation were selected. The dependence of the adhesion and deposition efficiency on the selected variables was approximated by a second-order polynomial. In accordance with the developed matrix of the experiment (central compositional design), a coating of the studied powder was deposited. The average value of these parameters was determined using standard methods for studying the adhesion strength (ASTM C603) and the deposition efficiency for thermal spray coatings. Based on the results of experimental data, regression equations were obtained for adhesion and deposition efficiency. For the purpose of checking the adequacy of the model, an analysis of variance was performed. It was confirmed that the obtained empirical dependences can be used to predict the adhesion and deposition efficiency of cold spraying of coatings from a Ni+Al2O3 powder on VT3-1 titanium alloy in the specified ranges of values of spraying parameters. Multi-factor optimization of the spraying parameters in order to obtain maximum values of adhesion strength and deposition efficiency was performed using the response surface methodology in the Stat-Ease 360 software. Three-dimensional and contour graphs of the dependence of the adhesion and deposition efficiency on the studied parameters were developed from the obtained empirical models. The optimal combination of parameters of low-pressure cold spraying, which ensures the maximum adhesion (34.78 MPa) and deposition efficiency (29.46%) of the Ni+Al2O3 coating mixture, is the nozzle inlet temperature—537 °C, stand-off distance—11 mm, and powder feed rate—0.6 g s−1.

Enhancing the Microhardness of Coatings Produced by Cold Gas Dynamic Spraying through Multi-Reinforcement with Aluminum Powders Containing Fullerenes and Aluminum Nitride

Coatings with high hardness were successfully obtained using low-pressure cold spray (LPCS) technology from nanocrystalline powders based on the aluminum alloy AlMg6, which were multi-reinforced with 0.3 wt.% fullerenes and 10–50 wt.% AlN. The powders were synthesized through a two-stage high-energy ball milling process, resulting in a complex mechanical mixture consisting of agglomerates and micro-sized ceramic particles of AlN. The agglomerates comprise particles of the nanocomposite material AlMg6/C60 with embedded and surface-located, micro-sized ceramic particles of AlN. Scanning electron microscopy and EDS analyses demonstrated a uniform distribution of reinforcing particles throughout the coating volume. An X-ray diffraction (XRD) analysis of the coatings revealed a change in the predominant orientation of matrix alloy grains to a more chaotic state during deformation over the course of cold gas dynamic spraying. A quantitative determination of AlN content in the coating was achieved through the processing of XRD data using the reference intensity ratio (RIR) method. It was found that the proportion of transferred ceramic particles from the multi-reinforced powder to the coating did not exceed ~65%. Experimental evidence indicated that LPCS processing of mono-reinforced nanocrystalline powder composite AlMg6/C60 practically did not lead to the formation of a coating on the substrate and was limited to a monolayer with a thickness of ~10 µm. The microhardness of the monolayer coating obtained from the deposition of AlMg6/C60 powder was 181 ± 12 HV. Additionally, the introduction of 10 to 50 wt.% AlN into the powder mixture contributed to the enhancement of growth efficiency and an increase in coating microhardness by ~1.4–1.7 times. The obtained results demonstrate that the utilization of agglomerated multi-reinforced powders for cold gas dynamic spraying can be an effective strategy for producing coatings and bulk materials based on aluminum and its alloys with high microhardness.

The Preparation and Properties of Ni2Al3 Intermetallic Compound Coating

In this work, a Ni2Al3 intermetallic compound coating was prepared on 45 # steel by combining methods of low-pressure cold spray and heat treatment. Firstly, powders mixed with Ni powders, Al powders, and Al2O3 powders as a mass ratio of 20:6:4 were sprayed on surface of 45 # steel by low-pressure cold spraying technology to prepare a Ni-Al pre-coating. Subsequently, the pre-coating was annealed at 570 °C in an argon atmosphere for 12 h to obtain the Ni2Al3 intermetallic compound coating. The composite coating was characterized using TEM, SEM, and XRD. High temperature oxidation performance of the composite coating was analyzed by isothermal oxidation tests conducted at 600 °C in air atmosphere for 96 h. The results show that the composite coating is composed of Ni2Al3 phase. Under a high-temperature oxidation environment, a protective oxide film composed by Al2O3 and NiO was formed on the coating surface, which resulting in a superior high-temperature oxidation resistance compared to 15CrMo heat-resistant steel. The mechanism of the Ni2Al3 coating resistance to high-temperature oxidation is that an oxide film mainly composed of Al2O3 and NiO formed on the surface during the high-temperature oxidation process; this oxide film can effectively resist oxidation and protect the substrate material from oxidation at a high temperature of 600 °C.

Suggestion of a New Repair Technique for Steel Structures by Low-Pressure Cold Spray and Laser Cleaning

Suggestion of a New Repair Technique for Steel Structures by Low-Pressure Cold Spray and Laser Cleaning