Coatings

Open AccessArticle

Effect of Solid Sodium Silicate on Workability, Hydration and Strength of Alkali-Activated GGBS/Fly Ash Paste

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Coatings 2023, 13(4), 696; https://doi.org/10.3390/coatings13040696 (registering DOI) - 29 Mar 2023

Abstract

Based on economic and environmental considerations, the recycling economy of mineral waste has been found to have great potential and economic benefits worldwide, in which alkali-activated cementitious materials are one of the main developing directions. The alkali activators commonly used in alkali-activated cementitious [...] Read more.

Based on economic and environmental considerations, the recycling economy of mineral waste has been found to have great potential and economic benefits worldwide, in which alkali-activated cementitious materials are one of the main developing directions. The alkali activators commonly used in alkali-activated cementitious materials are the composite activators of sodium silicate solution and solid sodium hydroxide, which not only need to deal with high viscosity and corrosive chemicals, but also need to be prepared in advance and properly stored. In this paper, ground granulated blast furnace slag (GGBS) and fly ash were used as precursors, while solid sodium silicate powder was applied as the alkali activator. In addition, the precursors were mixed with the activator in advance and activated by adding water to prepare alkali-activated GGBS/fly ash cement. The influence of precursor components, the dosage of the alkali activator and the liquid–solid ratio on the working performance, mechanical strength and hydration process of alkali-activated cement was studied. The results showed that the further incorporation of GGBS accelerated the alkali activation reaction rate and improved the strength of the specimen. However, in the specimen with GGBS as the main component of the precursor, the main hydration product was C-A-S-H gel, which was different in the structural order and quantity. The compressive strength indicated that there was the best amount of activator to match it in terms of the precursor with certain components. A too high or too low amount of activator will hinder the alkali activation reaction. This study can provide some significant reference material for the use of solid alkali activators in alkali-activated cementitious materials. Full article

(This article belongs to the Special Issue Novel Green Pavement Materials and Coatings)

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Open AccessArticle

Investigation on Microstructure and Properties of the Electrodeposited Ni-SiC Composite Coating

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Coatings 2023, 13(4), 695; https://doi.org/10.3390/coatings13040695 - 29 Mar 2023

Abstract

The current work synthesized Ni-SiC composite coating with different SiC microparticle contents. The role of the SiC microparticle in designing the Ni-SiC composite microstructure was revealed. The SiC microparticle physically interrupted the continuous growth of the underlying columnar Ni grains. The columnar Ni [...] Read more.

The current work synthesized Ni-SiC composite coating with different SiC microparticle contents. The role of the SiC microparticle in designing the Ni-SiC composite microstructure was revealed. The SiC microparticle physically interrupted the continuous growth of the underlying columnar Ni grains. The columnar Ni grain between the embedded SiC microparticle grew without disturbance. Only upon SiC microparticles was a new layer starting with refined Ni grains observable. The vertical columnar Ni grains reappeared as the position departed the SiC microparticle upper surface. The increase in the contents of the SiC microparticle led to an increased level of grain refinement and the elimination of the (200) fiber texture. Besides that, the number of V-shaped valleys increased as well. Corrosion testing results show that the corrosion resistance of Ni-SiC composite coating increased with the increased SiC contents, which was mainly due to the optimized microstructure. Full article

(This article belongs to the Special Issue Advances in the Evaluation of Fatigue Life and Corrosion of Composite Materials)

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Open AccessArticle

Microstructure and Corrosion Behavior of Fe-Based Austenite-Containing Composite Coatings Using Supersonic Plasma Spraying

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Coatings 2023, 13(4), 694; https://doi.org/10.3390/coatings13040694 - 28 Mar 2023

Abstract

The Fe-based austenite-containing composite coatings with various contents (3 vol.%, 6 vol.%, 9 vol.%, 12 vol.%) of austenite powder additions were created by supersonic plasma spraying on 45 steel substrates. The microstructure, phase composition, microhardness, and porosity of the composite coatings were examed. [...] Read more.

The Fe-based austenite-containing composite coatings with various contents (3 vol.%, 6 vol.%, 9 vol.%, 12 vol.%) of austenite powder additions were created by supersonic plasma spraying on 45 steel substrates. The microstructure, phase composition, microhardness, and porosity of the composite coatings were examed. Moreover, special attention was paid to the effect of austenite powder on the corrosion resistance of the austenite-containing composite coatings. The results found that the addition of austenite powders could significantly improve the corrosion resistance of Fe-based coatings, which is mainly due to three correlated phenomena caused by the austenite particles. First, austenite particles significantly reduce the porosity of the austenite-containing composite coatings and form a denser coating structure due to their low melting point and good chemical compatibility with the Fe-based alloy. Further, austenite particles help to refine the grains and increase the grain boundary density. Last but not least, austenite particles help to generate more diffusely distributed second phases in the coating, improving the chemical homogeneity and hardness of the coating. Full article

(This article belongs to the Section Corrosion, Wear and Erosion)

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Open AccessReview

A Mini-Review of Synthetic Organic and Nanoparticle Antimicrobial Agents for Coatings in Textile Applications

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Michail Karypidis

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Evangelos Karanikas

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Aikaterini Papadaki

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Eleftherios G. Andriotis

Coatings 2023, 13(4), 693; https://doi.org/10.3390/coatings13040693 (registering DOI) - 28 Mar 2023

Abstract

Many synthetic compounds have been applied to impart antimicrobial properties to fabrics. In this review, the types of bacteria are described. Furthermore, synthetic antimicrobial agents, namely quaternary ammonium compounds (QACs), polyhexamethylene biguanide (PHMB), triclosan, and nitrogen-halamines (N-halamines), are discussed along with their properties, [...] Read more.

Many synthetic compounds have been applied to impart antimicrobial properties to fabrics. In this review, the types of bacteria are described. Furthermore, synthetic antimicrobial agents, namely quaternary ammonium compounds (QACs), polyhexamethylene biguanide (PHMB), triclosan, and nitrogen-halamines (N-halamines), are discussed along with their properties, their advantages and disadvantages. Although synthetic antimicrobial agents neutralise microorganisms, some adversely affect the environment, safety and health. These problems led to a novel generation of antimicrobial coating treatments on textiles, such as copper nanoparticles (CNPs) and silver nanoparticles (AgNPs) formed on plant extracts, chitosan and green synthesis, with a lower environmental impact but unaltered premium antimicrobial performance and improved durability. Full article

(This article belongs to the Special Issue Coatings for Antimicrobial Textiles)

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Open AccessArticle

Investigating the Synergistic Effect of Electrochemical Texturing and MoSeC Coatings on the Frictional Behaviour of Lubricated Contacts

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Manoj Rajankunte Mahadeshwara

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Coatings 2023, 13(4), 692; https://doi.org/10.3390/coatings13040692 - 28 Mar 2023

Abstract

The materials used for the piston cylinders of automobile engines, or the ring and tappets of various mechanical components, are continuously experiencing lubricated sliding motions. These surfaces are prone to damage due to the various tribological aspects of friction and wear. Hence, enhancing [...] Read more.

The materials used for the piston cylinders of automobile engines, or the ring and tappets of various mechanical components, are continuously experiencing lubricated sliding motions. These surfaces are prone to damage due to the various tribological aspects of friction and wear. Hence, enhancing their surface properties would contribute to increasing their life and saving energy and resources. For many decades surface texturing and surface coating technology have been studied to improve the surface tribological behaviours of the materials. In the present study, the steel surface was textured with electrochemical processing (ECP) and post-coating with transition metal dichalcogenides (TMD) using a molybdenum-selenium-carbon (MoSeC) film. A comparative study was conducted to investigate the synergistic effect of surface texturing and coating to improve frictional properties on the steel surface. The block-on-ring experiments were performed under lubricated conditions to understand the improvement of COF at different lubrication regimes. It has been seen that the MoSeC-coated circular patterns exhibited improvements in the frictional properties at all the lubricated conditions if compared with smooth surfaces. Full article

(This article belongs to the Special Issue Advanced Multielement Coatings: Deposition, Materials and Applications)

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Open AccessFeature PaperArticle

Thermoelectric and Structural Properties of Sputtered AZO Thin Films with Varying Al Doping Ratios

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Muhammad Isram

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Riccardo Magrin Maffei

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Coatings 2023, 13(4), 691; https://doi.org/10.3390/coatings13040691 - 28 Mar 2023

Abstract

Nanomaterials can be game-changers in the arena of sustainable energy production because they may enable highly efficient thermoelectric energy conversion and harvesting. For this purpose, doped thin film oxides have been proven to be promising systems for achieving high thermoelectric performances. In this [...] Read more.

Nanomaterials can be game-changers in the arena of sustainable energy production because they may enable highly efficient thermoelectric energy conversion and harvesting. For this purpose, doped thin film oxides have been proven to be promising systems for achieving high thermoelectric performances. In this work, the design, realization, and experimental investigation of the thermoelectric properties exhibited by a set of five Al:ZnO thin films with thicknesses of 300 nm and Al doping levels ranging from 2 to 8 at.% are described. Using a multi-technique approach, the main structural and morphological features of the grown thin films are addressed, as well as the electrical and thermoelectrical transport properties. The results show that the samples exhibited a Seebeck coefficient absolute value in the range of 22–33 μV/K, assuming their maximum doping level was 8 at.%, while the samples’ resistivity was decreased below 2 × 10⁻³ Ohm·cm with a doping level of 3 at.%. The findings shine light on the perspectives of the applications of the metal ZnO thin film technology for thermoelectrics. Full article

(This article belongs to the Special Issue Thermoelectric Thin Films for Thermal Energy Harvesting)

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Open AccessArticle

Effects of Substrates on Thin-Film Growth of Nickel Zinc Ferrite by Spin-Spray Deposition

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Coatings 2023, 13(4), 690; https://doi.org/10.3390/coatings13040690 - 28 Mar 2023

Abstract

In certain applications, such as on-chip integrated inductors, ferrite materials are highly desirable owing to their superior magnetic and insulation properties. Spin-spray deposition is a promising method for producing high-quality thin films of ferrite, as it does not require a vacuum and can [...] Read more.

In certain applications, such as on-chip integrated inductors, ferrite materials are highly desirable owing to their superior magnetic and insulation properties. Spin-spray deposition is a promising method for producing high-quality thin films of ferrite, as it does not require a vacuum and can operate at low temperatures. A comprehensive analysis was conducted to investigate the influence of the substrate on the microstructure and magnetic properties of the thin films, and the growth mechanism of this phenomenon was discussed. In addition, first-order reversal curve measurements were used to study the coercivity and grain size distribution. The results indicate that thermal conductivity played a significant role in determining the thin-film growth during spin spray deposition. Polyimide is considered a more suitable substrate under this process due to its appropriate thermal conductivity, which results in more uniform grain distribution and improved magnetic properties, with maximum permeability and a cutoff frequency reaching 55 and 485 MHz, respectively. Our results provide valuable insights into the mechanism of spin-spray deposition and offer an effective way to tune the performance of ferrite thin-film materials. Full article

(This article belongs to the Special Issue Functional Magnetic and Dielectric Composites: Fabrication, Properties and Applications)

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Graphical abstract

Open AccessArticle

Mixing, Fast and Slow: Assessing the Efficiency of Electronically Conductive Networks in Hard Carbon Anodes

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Manisha Anne Sawhney

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Jenny Baker

Coatings 2023, 13(4), 689; https://doi.org/10.3390/coatings13040689 - 28 Mar 2023

Abstract

This work aimed to answer fundamental questions about the optimal processing and formulation of hard carbon electrodes typical of those anticipated in commercial sodium-ion cells. Procedurally simple tests were proposed to compare the effects of slurry mixing energy and conductive additives on the [...] Read more.

This work aimed to answer fundamental questions about the optimal processing and formulation of hard carbon electrodes typical of those anticipated in commercial sodium-ion cells. Procedurally simple tests were proposed to compare the effects of slurry mixing energy and conductive additives on the morphology of and conductive networks in electrodes made with hard carbons from two different manufacturers. Long-range and short-range electronic conductivity was quantified with high repeatability for samples of each hard carbon electrode produced on different days. The most significant changes induced by mixing energy were observed in the electrodes produced without conductive additives, which was found to relate to post-processing particle size. Hard carbon from one source was pulverized by high energy mixing, replacing the electronic effect of conductive additives while increasing pore tortuosity and impedance. These findings recommend evaluating the dry electrode through-resistance as a complement to quantifying pre-cycling impedance to validate mixing protocol and the application of conductive additives in hard carbon electrodes. These procedures can also serve as reliable low-cost methods for quality control at early stages of sodium-ion anode manufacturing. Full article

(This article belongs to the Topic Characterization of Electrochemical Materials)

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Open AccessArticle

The Effect of Sintering Temperature on Vickers Microhardness and Flexural Strength of Translucent Multi-Layered Zirconia Dental Materials

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Bashayer Alfahed

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Abdullah Alayad

Coatings 2023, 13(4), 688; https://doi.org/10.3390/coatings13040688 - 28 Mar 2023

Abstract

This study evaluated the effects of the sintering temperature on Vickers microhardness and three-point flexural strength values of two multi-layered zirconia materials. Multi-layered zirconia systems with four distinct layers were selected: DD cube ONE ML (4Y-TZP) and DD cubeX² ML (5Y-TZP). In [...] Read more.

This study evaluated the effects of the sintering temperature on Vickers microhardness and three-point flexural strength values of two multi-layered zirconia materials. Multi-layered zirconia systems with four distinct layers were selected: DD cube ONE ML (4Y-TZP) and DD cubeX² ML (5Y-TZP). In total, 96 plate-shaped A2-shade specimens were obtained using individual layers of these two zirconia materials. The individual layers were then divided equally into batches with three different sintering temperatures (1300, 1450, and 1600 °C), and the Vickers microhardness was assessed. Another group of 72 bar-shaped specimens was prepared from the same materials. These were similarly divided into three different sintering temperatures, and the flexural strength was assessed. SEM was used to conduct fractographic analyses. The data were analyzed using SPSS 24.0 software with a p-value < 0.05. The microhardness and flexural strength of 4Y-TZP were higher than those of the 5Y-TZP at all the sintering temperatures. A significant difference was found in the microhardness and flexural strength values between groups sintered at different sintering temperatures (p < 0.05). The highest microhardness and flexural strength values were found at 1450 °C (p < 0.05). The microhardness values of different layers were not significantly different (p > 0.05). The sintering temperature and type of ceramic material significantly affected the microhardness and flexural strength. However, the layers did not significantly affect the microhardness. Full article

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Open AccessArticle

Boron-Based Mildew Preventive and Ultraviolet Absorbent Modification of Waterborne Polyurethane Coatings on Laminated Bamboo

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Coatings 2023, 13(4), 687; https://doi.org/10.3390/coatings13040687 - 28 Mar 2023

Abstract

In order to improve the outdoor exposure performance of laminated bamboo, boric acid/borax and UV absorbents, including triazole (UV1130), nano–TiO₂, and nano–SiO₂, were used to modify waterborne polyurethane (WPU) coatings, respectively. The physical and chemical properties of the coatings [...] Read more.

In order to improve the outdoor exposure performance of laminated bamboo, boric acid/borax and UV absorbents, including triazole (UV1130), nano–TiO₂, and nano–SiO₂, were used to modify waterborne polyurethane (WPU) coatings, respectively. The physical and chemical properties of the coatings with and without modification were evaluated by adhesion strength, contact angle, wear, and temperature-resistance experiments. The antimildew properties of the coatings were evaluated by the bacteriostatic zone method, and the pyrolysis characteristics were investigated through TG–FTIR analysis. The results showed that, when compared with the unmodified WPU coating, the coatings with different modifications had stronger wear resistance; the mass loss of the best C4 coating was only 0.0078 g, which was 0.0203 g less than that of the unmodified C0 coating. However, when compared to the unmodified coating, the wettability of the modified coating increased to different degrees, and the contact angle of the C4 coating with the most obvious effect was only 36.50°. During the curing process of the modified coatings, the UV absorbents and boric acid/borax would interact with the C–N, C–O, and C=O bonds in the coating and change the molecular structure of the WPU. The thermal stability of the coatings with different modifications was enhanced. The best result, a 76.27% weight loss, was observed in the modified coating with boric acid/borax and 1.0% nano–TiO₂. Different modified coatings had a certain degree of control effect on Aspergillus Niger, and the reason for this was considered the combined effect of boric acid/borax and UV absorbents. Full article

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Open AccessArticle

A Wind Tunnel Test of the Anti-Icing Properties of MoS₂/ZnO Hydrophobic Nano-Coatings for Wind Turbine Blades

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Coatings 2023, 13(4), 686; https://doi.org/10.3390/coatings13040686 - 27 Mar 2023

Abstract

Wind turbines operating in cold regions are prone to blade icing, which seriously affects their aerodynamic characteristics and safety performance. Coatings are one of the effective solutions to the icing problem on wind turbine blades. In this study, MoS₂/ZnO/PDMS superhydrophobic nano-anti-icing [...] Read more.

Wind turbines operating in cold regions are prone to blade icing, which seriously affects their aerodynamic characteristics and safety performance. Coatings are one of the effective solutions to the icing problem on wind turbine blades. In this study, MoS₂/ZnO/PDMS superhydrophobic nano-anti-icing coatings were prepared using the hydrothermal method and the liquid phase method. SEM revealed that the MoS₂/ZnO coating was a typical superhydrophobic nanostructure with an ultra-thin sheet-like morphology of clusters and a hilly nano-rough structure, with contact angles (CA) of 152.1° and 4.7° with water droplets and the sliding angle (SA), respectively. The MoS₂/ZnO/PDMS coating had an adhesion strength to ice of 78 kPa, which was 60.2% lower than an uncoated surface. The icing effects of the NACA0018 airfoil blade model with or without MoS₂/ZnO coatings were studied at different ambient temperatures and wind speeds using the icing wind tunnel test. The results showed that, compared to uncoated blades, the level of icing was lower on the blade airfoil surface that was coated with MoS₂/ZnO. At 10 m/s and −10 °C, the icing thickness and icing area of the leading edge of the blade airfoil were 13.7% and 28.3% lower, respectively. This study provides a valuable reference for the development of anti-icing coatings for wind turbine blades. Full article

(This article belongs to the Special Issue Recent Advances in Superhydrophobic and Icephobic Surfaces)

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Open AccessArticle

Effect of Fluorocarbon Polymers on Hydrophobicity, Wear Resistance and Corrosion Resistance of Epoxy Resins

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Coatings 2023, 13(4), 685; https://doi.org/10.3390/coatings13040685 - 27 Mar 2023

Abstract

In order to meet the anticorrosion and wear resistance requirements of petroleum pipelines, we selected a polymer (FC) containing difunctional hydroxyl propyl acrylate (HPA) and perfluoroalkyl ethyl acrylate (TEAc-N) free radical polymerization to prepare hydrophobic fluorocarbon chain oil and a hydroxyl special functional [...] Read more.

In order to meet the anticorrosion and wear resistance requirements of petroleum pipelines, we selected a polymer (FC) containing difunctional hydroxyl propyl acrylate (HPA) and perfluoroalkyl ethyl acrylate (TEAc-N) free radical polymerization to prepare hydrophobic fluorocarbon chain oil and a hydroxyl special functional group. Combined with tetrafluororesin (F4), the hydrophobic, wear-resistant and corrosion-resistant properties of epoxy coating were improved. The optimum synthesis ratio of TEAc-N:HPA was 9:1, and the FC polymer with the best hydrophobicity was prepared. The hydrophobic angle of the coating was 100.3% higher than that of pure Q235 section steel. By adding 5 wt.% of FC to epoxy resin (EP), the hydrophobicity increased by 65.4% and oleophobicity increased by 32.1% compared with pure EP. The coefficient of friction was reduced by 73.8%. EIS test results showed that the impedance modulus in the low frequency region (|Z|_0.01 Hz) was two orders of magnitude higher than that of the pure epoxy coating. The composite coating has sufficient utility to meet the wear, heat and corrosion resistance requirements for oil pipeline transportation. Full article

(This article belongs to the Special Issue Advanced Polymeric Materials and Coatings: Synthesis, Properties and Applications)

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Open AccessArticle

Enterosorbents Based on Rhubarb Biomass with a Hybrid Polymer-Inorganic Coating for the Immobilization of Azaheterocyclic Mycotoxins

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Coatings 2023, 13(4), 684; https://doi.org/10.3390/coatings13040684 - 27 Mar 2023

Abstract

The aim of the study was the improvement of the phytosorbent range to solve the actual problems of preventing mycotoxicosis caused by numerous types of azaheterocyclic mycotoxins. Technological approaches to structural released pectin and to the formation of a surface layer that was [...] Read more.

The aim of the study was the improvement of the phytosorbent range to solve the actual problems of preventing mycotoxicosis caused by numerous types of azaheterocyclic mycotoxins. Technological approaches to structural released pectin and to the formation of a surface layer that was capable of adhesive interaction with montmorillonite particles was identified. The increase in the material porosity and the formation of a hybrid polymer-inorganic coating on a cellulose matrix surface were revealed by scanning electron microscopy and gas adsorption. The modification of rhubarb biomass increased sorption capacity in comparison with the raw material seven-fold. The properties of rhubarb pectin and a hybrid composite based on it were investigated using FTIR spectroscopy, viscometry, laser diffraction and X-ray diffraction analysis. The results were compared with the characteristics of commercial citrus pectin. Models of the molecular structure of the polymer chain and the spatial interaction between macromolecules in the structure of the sorbing grain were proposed based on the pectin chemical state. The influence of the pectin structural organization on the kinetic parameters of the pH-regulated sorption of the test alkaloid under conditions simulating the functioning of the human digestive organs and those of farm animals was traced. The results of the studies allow prognoses on the sorption binding of alkaloids and determinations of the dosage of pectin-containing phytopreparations for mycotoxicos prevention. Full article

(This article belongs to the Special Issue Preparation and Applications of Functional Inorganic Coatings, Glass, Ceramics)

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Open AccessArticle

Inkjet Printing of High Aspect Ratio Silver Lines via Laser-Induced Selective Surface Wetting Technique

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Coatings 2023, 13(4), 683; https://doi.org/10.3390/coatings13040683 - 27 Mar 2023

Abstract

The field of printed electronics for highly integrated circuits and energy devices demands very fine and highly conductive electric interconnections. In this study, conductive lines having a high cross-sectional aspect ratio were printed via the inkjet printing of Ag nanoparticle inks assisted by [...] Read more.

The field of printed electronics for highly integrated circuits and energy devices demands very fine and highly conductive electric interconnections. In this study, conductive lines having a high cross-sectional aspect ratio were printed via the inkjet printing of Ag nanoparticle inks assisted by a laser-induced selective surface wetting technique: a hydrophobic layer of self-assembled monolayer-treated ZnO nanorods was coated on a glass substrate and selectively ablated by a laser to form micro-channels for the inkjet, whose surface energy changed from 36.3 mJ/m² to 51.5 mJ/m² before and after the laser irradiation. With the varying width of the laser-ablated channels and pitch of jetted ink drops, the 3D shapes of the printed silver lines were measured to investigate their effects on the widths, heights, and uniformities of the printed patterns. The results showed that the present technique realized a uniform line of 35 μm width and 0.46 μm average thickness, having an aspect ratio of 0.013, which is 7.6 times higher than that printed on bare glass. Full article

(This article belongs to the Special Issue Printed Functional Thin Films for Electronic, Optoelectronic and Sensing Applications)

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Open AccessArticle

Preparation of Wear-Resistant Superhydrophobic Coatings Based on a Discrete-Phase Adhesive

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Coatings 2023, 13(4), 682; https://doi.org/10.3390/coatings13040682 - 27 Mar 2023

Abstract

Among the many methods to prepare superhydrophobic coatings, the liquid spraying method has the advantages of simple operation, low equipment and substrate requirements, and a low cost to achieve large-scale industrialization. However, superhydrophobic coatings prepared using the existing one-step and two-step spraying methods [...] Read more.

Among the many methods to prepare superhydrophobic coatings, the liquid spraying method has the advantages of simple operation, low equipment and substrate requirements, and a low cost to achieve large-scale industrialization. However, superhydrophobic coatings prepared using the existing one-step and two-step spraying methods are not wear resistant, and the failure mechanism is also not clear. After preparing coatings using existing methods and conducting wear tests, we show that the reason for their lack of wear resistance is the excessive bonding caused by the nanoparticles embedded in the continuous-phase adhesive, or the low bonding caused by adhesion to the adhesive surface. Based on the above conclusion, we propose a method to transform a continuous-phase adhesive into a discrete-phase adhesive via phase separation, after which it is mixed with nanoparticles for spraying. This new method allows the nanoparticles to bond to the adhesive while avoiding embedding, which avoids the shortcomings of existing methods. Consequently, coatings fabricated using the new method have better wear resistance properties and important significance for practical applications. Full article

(This article belongs to the Special Issue Hydrophobic and Anti-icing Coatings)

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Open AccessArticle

Study on the Matching of Surface Texture Parameters and Processing Parameters of Coated Cemented Carbide Tools

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Haochuan Yang

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Shucai Yang

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Xin Tong

Coatings 2023, 13(4), 681; https://doi.org/10.3390/coatings13040681 - 27 Mar 2023

Abstract

Placing micro-textures on a tool surface can play an anti-wear and friction-reducing role and capture impurities and improve the tool-chip friction state, thus improving the cutting performance of the tool and the quality of the workpiece. To ensure the processing quality in the [...] Read more.

Placing micro-textures on a tool surface can play an anti-wear and friction-reducing role and capture impurities and improve the tool-chip friction state, thus improving the cutting performance of the tool and the quality of the workpiece. To ensure the processing quality in the micro-texture-coated tool-cutting process, the process parameters and micro-texture parameters are limited to smaller parameters, which reduces the processing efficiency and increases the cost. Aiming at this problem, this paper designs orthogonal experiments of the cutting process and micro-texture parameters, builds an experimental platform for milling titanium alloy with a micro-texture-coated ball-end milling cutter, analyzes the influence of cutting parameters on tool milling performance and workpiece quality, establishes a high fitting prediction model, and optimizes parameters. The results show that the cutting parameters significantly affect the milling force, tool wear, and workpiece surface roughness, which are in the first response level, and the micro-texture parameters, which are in the second response level. It is proven that micro-texture has anti-wear and anti-friction effects, and it is found that micro-texture parameters affect the evaluation index by changing the distribution state of the micro-texture. It is found that the multiple linear regression model fits better. Parameter optimization results are: v = 159.4232 (m/min), a_p = 0.211 (mm), f = 0.06 (mm/r), micro-pit diameter D = 62.3429 (μm), distance from blade L = 121.5184 (μm), and micro-pit spacing L₁ = 235.6443 (μm). It provides some guidance for the selection of micro-texture parameters and cutting parameters on a micro-texture-coated tool. Full article

(This article belongs to the Special Issue Surface Modification of Engineering and Functional Materials)

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Open AccessArticle

First-Principle Study of the Interface of Al₂O₃/CoCr Metal-Based Composites

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Coatings 2023, 13(4), 680; https://doi.org/10.3390/coatings13040680 - 27 Mar 2023

Abstract

In this work, the interface bonding properties of Al₂O₃/CoCr metal matrix composites were calculated using first principles after Al₂O₃ was added to traditional CoCr alloys. The phase and microstructure of the CoCr alloy and the Al [...] Read more.

In this work, the interface bonding properties of Al₂O₃/CoCr metal matrix composites were calculated using first principles after Al₂O₃ was added to traditional CoCr alloys. The phase and microstructure of the CoCr alloy and the Al₂O₃/CoCr metal matrix composites were characterized. The results indicate that the interface binding ability of the Al₂O₃ (111)/CoCr (111) interface model was the strongest, and the electronic overlap of its interface was the highest. The charge density was the strongest, the overlap area was the highest, and there was a charge accumulation area at the interface. Meanwhile, the influence of the amount of added Al₂O₃ on the bonding strength of the Al₂O₃/CoCr interface was studied. It was concluded that the interface bonding ability of the Al₂O₃ (111)/CoCr (111) interface was the best when 5% Al₂O₃ was added. By studying the phase composition and microstructure of Al₂O₃/CoCr metal matrix composites, it was shown that the microstructure of the composites was uniform and dense after added Al₂O₃, Al₂O₃, M₆C, and CoAl₂O₄ phases appeared, and the grain size was finer. Full article

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Open AccessArticle

Cutting Energy Consumption Modelling of End Milling Cutter Coated with AlTiCrN

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Coatings 2023, 13(4), 679; https://doi.org/10.3390/coatings13040679 - 27 Mar 2023

Abstract

As an indispensable piece of equipment in the manufacturing industry, the machine tool is low-energy-efficiency and high-energy-consumption in operation. Therefore, it is urgent to establish a cutting energy consumption model to guide production and reduce the energy consumption of the machining process. In [...] Read more.

As an indispensable piece of equipment in the manufacturing industry, the machine tool is low-energy-efficiency and high-energy-consumption in operation. Therefore, it is urgent to establish a cutting energy consumption model to guide production and reduce the energy consumption of the machining process. In this paper, the AlTiCrN-coated cutting tool is taken as the object of study, and the cutting energy consumption model is established. The cutting energy consumption model is composed of a machining time model and a cutting power model. The cutting power model can be divided into the shear deformation power model of the workpiece, the friction power model of the flank surface and the friction power model of the rake surface. The influence of the edge shape is taken into account in the establishment of the friction power model of the flank surface. The machining time model considering the S-type acceleration and deceleration stage is established. The accuracy of the model was verified by experiments. Experimental results show that the model has high accuracy. The Taguchi method was used to carry out the numerical experiment with the cutting energy consumption of the machine tool as the response. The influences of cutting parameters on energy consumption are analyzed. Cutting width is the most important factor, followed by cutting depth, then feed rate and spindle speed. The physical principle of the influence of cutting parameters on cutting energy consumption is revealed. Full article

(This article belongs to the Special Issue Surface Modification of Engineering and Functional Materials)

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Open AccessArticle

Study of Structural, Mechanical, and Corrosion Resistance of a Nanocomposite CrSiN/CrN/Cr Coating Deposited on AZ31: Effects of Deposition Time

by

Changqing Cui

and

Chunyan Yang

Coatings 2023, 13(4), 678; https://doi.org/10.3390/coatings13040678 - 26 Mar 2023

Abstract

To improve the surface properties of Mg alloys and expand the applications of CrN-based materials, composite CrSiN coatings consisting of amorphous Si₃N₄ and nano CrN phases have been prepared on AZ31 based on the theory of fine grain strengthening and [...] Read more.

To improve the surface properties of Mg alloys and expand the applications of CrN-based materials, composite CrSiN coatings consisting of amorphous Si₃N₄ and nano CrN phases have been prepared on AZ31 based on the theory of fine grain strengthening and multigrain boundaries. The effect of the thickness of the coating on the structure and properties was investigated. The microstructure was studied by means of X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The mechanical properties, adhesion properties, and corrosion resistance were investigated using a nanoindentater, scratch testers, and electrochemical workstations. The results show that the coating consists of a face-centered cubic CrN phase, that Si₃N₄ is not found in the diffraction pattern, and that the HRTEM images show a composite structure of amorphous and nanocrystalline phases. With the increase in deposition time (thickness), the surface roughness decreases, the defects disappear, and the interface has no visible defects. Moreover, the hardness and elastic modulus of the coating increase, corrosion resistance improves, adhesion performance first increases and then decreases. The adhesion between coating and substrate reaches the maximum when sputtering time is 50 min, which corresponds to the CrSiN thickness of 0.79 μm. Full article

(This article belongs to the Special Issue Advances in Corrosion Resistant Coatings Volume II)

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