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Open AccessArticle

Improvement of Structures and Properties of Al₂O₃ Coating Prepared by Cathode Plasma Electrolytic Deposition by Incorporating SiC Nanoparticles

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Coatings 2022, 12(5), 580; https://doi.org/10.3390/coatings12050580 - 24 Apr 2022

Viewed by 1033

Abstract

A serious issue in the preparation of Al₂O₃ coatings by cathode plasma electrolytic deposition (CPED) is that the coatings have a porous structure, which is detrimental to their protective performance. Therefore, to address this problem, SiC nanoparticles are incorporated into [...] Read more.

A serious issue in the preparation of Al₂O₃ coatings by cathode plasma electrolytic deposition (CPED) is that the coatings have a porous structure, which is detrimental to their protective performance. Therefore, to address this problem, SiC nanoparticles are incorporated into the Al₂O₃ coating in this study. A series of Al₂O₃–SiC composite coatings are efficaciously prepared on the surface of 316L stainless steel by CPED. The microstructures, compositions and phase components of the composite coatings are characterized; the electrochemical corrosion resistance and tribological behavior are evaluated; and the mechanism of SiC nanoparticles in the coating formation process is discussed in detail. The results indicate that the Al₂O₃ coating prepared by CPED consists of α-Al₂O₃ and γ-Al₂O₃, and the former is the main crystalline phase. With the incorporation of SiC nanoparticles in the coating, the content of α-Al₂O₃ gradually decreases, almost disappearing, accompanied by an increase in γ-Al₂O₃ as the main crystalline phase. The incorporation of SiC nanoparticles significantly reduces the surface irregularity and roughness of Al₂O₃ coatings and remarkably improves the corrosion resistance and wear resistance of the Al₂O₃ coatings. The improvement in corrosion resistance and anti-wear properties can be explained by the fact that the SiC nanoparticles effectively weaken electrical breakdown and increase the compactness of the coatings. Full article

(This article belongs to the Special Issue New Advances in Ceramic Coatings and Its Applications)

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Open AccessCommunication

Mechanical Properties Durability of Sc₂O₃-Y₂O₃ Co-Stabilized ZrO₂ Thermal Barrier Materials for High Temperature Application

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Coatings 2022, 12(2), 155; https://doi.org/10.3390/coatings12020155 - 27 Jan 2022

Cited by 1 | Viewed by 1373

Abstract

The poor phase stability of conventional 6–8 wt.% yttria-partially stabilized zirconia (YSZ) results in the formation of detrimental cracks in thermal barrier coatings (TBCs) as well as the decrease of fracture toughness, limiting its long-term application above 1200 °C. Here, we try to [...] Read more.

The poor phase stability of conventional 6–8 wt.% yttria-partially stabilized zirconia (YSZ) results in the formation of detrimental cracks in thermal barrier coatings (TBCs) as well as the decrease of fracture toughness, limiting its long-term application above 1200 °C. Here, we try to prove that a higher t′-phase stability is the prerequisite for the mechanical properties durability of ZrO₂-based TBC materials. Compared with YSZ ceramic, 7.0 mol.% Sc₂O₃ and 0.5 mol.% Y₂O₃ co-stabilized ZrO₂ (ScYSZ) shows a superior t′ phase stability at 1300 °C. In addition, the fracture toughness of ScYSZ is nearly stable after being annealed at 1300 °C for 0–40 h, while the value of YSZ gradually declines during the aging process. The stable fracture toughness of ScYSZ is closely related to its prominent t′ phase stability. The elastic modulus of ScYSZ is nearly unchanged and lower than that of YSZ. The excellent stability of the phase structure and mechanical properties makes ScYSZ a great potential material for next generation high-temperature TBCs. Full article

(This article belongs to the Special Issue New Advances in Ceramic Coatings and Its Applications)

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Open AccessArticle

Comparative Studies of Piston Crown Coating with YSZ and Al₂O₃·SiO₂ on Engine out Responses Using Conventional Diesel and Palm Oil Biodiesel

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Coatings 2021, 11(8), 885; https://doi.org/10.3390/coatings11080885 - 23 Jul 2021

Cited by 3 | Viewed by 2309

Abstract

In this study, the effect of a thermal barrier coating with yttria-stabilized zirconia (YSZ) and aluminum silicate (Al₂O₃·SiO₂) alongside an NiCrAl bond coat on the engine performance and emission analysis was evaluated by using conventional diesel and [...] Read more.

In this study, the effect of a thermal barrier coating with yttria-stabilized zirconia (YSZ) and aluminum silicate (Al₂O₃·SiO₂) alongside an NiCrAl bond coat on the engine performance and emission analysis was evaluated by using conventional diesel and pure palm oil biodiesel. These materials were coated on the piston alloy via plasma spray coating. The findings demonstrated that YSZ coating presented better engine performances, in terms of brake thermal efficiency (BTE) and brake-specific fuel consumption (BSFC) for both fuels. The piston with YSZ coating materials achieved the highest BTE (15.94% for diesel, 14.55% for biodiesel) and lowest BSFC (498.96 g/kWh for diesel, 619.81 g/kWh for biodiesel). However, Al₂O₃·SiO₂ coatings indicated better emission with lowest emissions of NO, CO, and CO₂ for both diesel and biodiesel. For the uncoated piston, the results indicated that the engine clocked the highest torque and power, especially on diesel fuel due to the high viscosity and low caloric value, and it recorded the lowest hydrocarbon emission due to the complete combustion of fuel in the engine. Hence, it was concluded that the YSZ coating could lead to better engine performance, while Al₂O₃·SiO₂ showed promising results in terms of greenhouse gas emission. Full article

(This article belongs to the Special Issue New Advances in Ceramic Coatings and Its Applications)

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Open AccessArticle

Effect of Thermal Barrier Coating on the Performance and Emissions of Diesel Engine Operated with Conventional Diesel and Palm Oil Biodiesel

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Coatings 2021, 11(6), 692; https://doi.org/10.3390/coatings11060692 - 09 Jun 2021

Cited by 8 | Viewed by 1554

Abstract

In this study, the performance and emission of a thermal barrier coating (TBC) engine which applied palm oil biodiesel and diesel as a fuel were evaluated. TBC was prepared by using a series of mixture consisting different blend ratio of yttria stabilized zirconia [...] Read more.

In this study, the performance and emission of a thermal barrier coating (TBC) engine which applied palm oil biodiesel and diesel as a fuel were evaluated. TBC was prepared by using a series of mixture consisting different blend ratio of yttria stabilized zirconia (Y₂O₃·ZrO₂) and aluminum oxide-silicon oxide (Al₂O₃·SiO₂) via plasma spray coating technique. The experimental results showed that mixture of TBC with 60% Y₂O₃·ZrO₂ + 40% Al₂O₃·SiO₂ had an excellent nitrogen oxide (NO), carbon monoxide (CO), carbon dioxide (CO₂), and unburned hydrocarbon (HC) reductions compared to other blend-coated pistons. The finding also indicated that coating mixture 50% Y₂O₃·ZrO₂ + 50% Al₂O₃·SiO₂ had the highest brake thermal efficiency (BTE) and lowest of brake specific fuel consumption (BSFC) compared to all mixture coating. Reductions of HC and CO emissions were also recorded for 60% Y₂O₃·ZrO₂ + 40% Al₂O₃·SiO₂ and 50% Y₂O₃·ZrO₂ + 50% Al₂O₃·SiO₂ coatings. These encouraging findings had further proven the significance of TBC in enhancing the engine performance and emission reductions operated with different types of fuel. Full article

(This article belongs to the Special Issue New Advances in Ceramic Coatings and Its Applications)

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Open AccessArticle

Highly Flexible Wind Turbine Blades Utilizing Corrugated Surface Hinges

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Mogeeb Elrahman Elsheikh

Coatings 2021, 11(6), 635; https://doi.org/10.3390/coatings11060635 - 26 May 2021

Cited by 2 | Viewed by 2111

Abstract

An anthropomorphic wind turbine blade was the suggested design that had a flexure hinge at root, middle, and tip regions. The inter-distances of the flexure hinges follow the Fibonacci sequence and resembled the natural finger through binding. Therefore, the present study designs various [...] Read more.

An anthropomorphic wind turbine blade was the suggested design that had a flexure hinge at root, middle, and tip regions. The inter-distances of the flexure hinges follow the Fibonacci sequence and resembled the natural finger through binding. Therefore, the present study designs various corrugated flexure hinges. NACA0012 is chosen as the basic airfoil for designing the corrugated flexure hinges with different geometrical profiles and leading edges. The designs are based on morphing technology and the main geometrical parameters of the corrugation, the pitch distance along the span and the height, are inspired by tubercles of the whale flippers. The study uses the finite element method to define the significant strength characteristics of each design flap-wise, edge-wise, torsional stiffness, and buckling resistance in order to assign the best fit corrugation profile for each region of the blade. Full article

(This article belongs to the Special Issue New Advances in Ceramic Coatings and Its Applications)

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Open AccessArticle

Bonding and Thermal-Mechanical Property of Gradient NiCoCrAlY/YSZ Thermal Barrier Coatings with Millimeter Level Thickness

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Coatings 2021, 11(5), 600; https://doi.org/10.3390/coatings11050600 - 19 May 2021

Cited by 6 | Viewed by 1444

Abstract

The thermal insulation properties of thermal barrier coatings (TBCs) can be significantly improved with increasing the coating thickness. However, due to the weak bonding of high-thickness TBCs, the low reliability and short lifetime greatly limits their application under some severe operating conditions. In [...] Read more.

The thermal insulation properties of thermal barrier coatings (TBCs) can be significantly improved with increasing the coating thickness. However, due to the weak bonding of high-thickness TBCs, the low reliability and short lifetime greatly limits their application under some severe operating conditions. In this study, a novel and high-efficiency synchronous dual powder feeding method is used to deposit a series of gradient NiCoCrAlY/YSZ coatings with millimeter level thickness. The tensile bonding strengths and residual stress state of coatings are evaluated in order to explore the effect of thickness on the bonding strength of coatings. The results suggested that, due to some micro-convex structure at the “GC/TC” interface and inside “GC” layer, the bonding strength of 1000-μm-thickness gradient NiCoCrAlY/YSZ TBCs with the 4:6 and 2:8 hybrid ratios is over 44 MPa compared to the common TBCs. The fracture position gradually shifts from NiCoCrAlY bond coat to NiCoCrAlY/YSZ transition zone and finally to the YSZ top coat owing to the different position of residual stress concentrations. After thermal cycling tests, the 1000-μm-thickness gradient coating exhibits a higher thermal cycling life. Some coarse cracks initiate and propagate at the bottom region of TBCs, which is mainly due to thermal expansion mismatch stress that finally results in the failure of the gradient coating between the “BC” layer and the substrate. Full article

(This article belongs to the Special Issue New Advances in Ceramic Coatings and Its Applications)

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Open AccessArticle

Characteristics and Crystal Structure of Calcareous Deposit Films Formed by Electrodeposition Process in Artificial and Natural Seawater

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Jun-Mu Park

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Myeong-Hoon Lee

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Seung-Hyo Lee

Coatings 2021, 11(3), 359; https://doi.org/10.3390/coatings11030359 - 21 Mar 2021

Cited by 2 | Viewed by 1708

Abstract

In this study, we tried to form the calcareous deposit films by the electrodeposition process. The uniform and compact calcareous deposit films were formed by electrodeposition process and their crystal structure and characteristics were analyzed and evaluated using various surface analytical techniques. The [...] Read more.

In this study, we tried to form the calcareous deposit films by the electrodeposition process. The uniform and compact calcareous deposit films were formed by electrodeposition process and their crystal structure and characteristics were analyzed and evaluated using various surface analytical techniques. The mechanism of formation for the calcareous deposit films could be confirmed and the role of magnesium was verified by experiments in artificial and natural seawater solutions. The highest amount of the calcareous deposit film was obtained at 5 A/m² while current densities between 1–3 A/m² facilitated the formation of the most uniform and dense layers. In addition, the adhesion characteristics were found to be the best at 3 A/m². The excellent characteristics of the calcareous deposit films were obtained when the dense film of brucite-Mg(OH)₂ and metastable aragonite-CaCO₃ was formed in the appropriate ratio. Full article

(This article belongs to the Special Issue New Advances in Ceramic Coatings and Its Applications)

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Review

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Open AccessReview

The Effects of CuO and SiO₂ on Aluminum AA6061 Hybrid Nanocomposite as Reinforcements: A Concise Review

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Muntadher Sabah Msebawi

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Azmah Hanim Mohamed Ariff

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Nur Ismarrubie Zahari

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Mohammed H. Rady

Coatings 2021, 11(8), 972; https://doi.org/10.3390/coatings11080972 - 15 Aug 2021

Viewed by 1545

Abstract

Hybrid composites are obtained by embedding multiple micro and nano reinforcements into the matrix materials. These hybrid composites are helpful to obtain the useful properties of matrix and reinforcement materials. Aluminum matrix is one the most common matrix materials due to its excellent [...] Read more.

Hybrid composites are obtained by embedding multiple micro and nano reinforcements into the matrix materials. These hybrid composites are helpful to obtain the useful properties of matrix and reinforcement materials. Aluminum matrix is one the most common matrix materials due to its excellent thermal and electrical properties. This review covers various aspects of nanoparticle-reinforced Al hybrid composites. Solid-state recycling of Al only consumes around 5% of the energy utilized in the conventional extraction and recycling methods. This review revolves around the induction of silica and copper oxide nanoparticles into the solid-state recycled Al matrix material to form the hybrid composite. These nanoparticles enhance stiffness, toughness, and high temperature stability for Al hybrid composites. A detailed analysis was carried out for AA6061-grade Al matrix materials along with the silica and copper oxide nanoparticles. The present work focused on the effects of nano silica and nano copper oxide particle reinforcements on Al-based composite manufactured via hot extrusion process. The composite fabrication through solid-state recycling is discussed in detail. A detailed analysis for the effects of volume fraction and wt.% of CuO and SiO₂ reinforcement particles was carried out by various characterization techniques. A detailed comparison in terms of mechanical performance of Al-based composites with the addition of nano silica and nano copper oxide particles is presented here to investigate the efficiency and performance of these particles. Full article

(This article belongs to the Special Issue New Advances in Ceramic Coatings and Its Applications)

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