Coating Materials Research Articles

Phosphate Esters: New Coating Materials for a Sustainable Release Paper.

AbstractPaper manufacturers have long used silicone as the coating agent for release liners. However, silicone‐based release paper is very difficult to recycle due to covalent bonds between silicone and fibers. The most suitable solution to overcome this problem is to use alternative coating materials with adequate release properties, provided that they can be easily repulped in typical paper recycling facilities. We proposed a coating agent composed of phosphate esters and dimethylacetamide in order to manufacture a recyclable and efficient release paper. Analyses carried out on coated sheets showed that phosphate esters allowed the formation of a surface with adequate release properties (low peeling force and surface free energy). In addition, the residual adhesion values obtained with phosphate esters confirmed that they are well anchored on the backing paper surface, thus limiting the mass transfer to the adhesive tape.

Fabrication of diisocyanate microcapsules for self-healing anti-corrosion coatings via integrating electrospraying and interfacial polymerization

Epoxy resins serve as useful material in anti-corrosion coatings. However, the development of microcracks during the processing or service life of a coating is an inevitable occurrence that markedly degrades its performance and shortens its lifespan. The incorporation of self-healing materials can prolong the coatings' lifespan and enhance the reliability of corrosion prevention processes. In this study, a microencapsulation method via integrating electrospraying and interfacial polymerization (ES-IP) was adopted to synthesize the microcapsules containing 4,4’-bis-methylene cyclohexane diisocyanate (HMDI) successfully. The self-healing capability of these microcapsules within the anti-corrosion coating was successfully validated. The prepared HMDI microcapsules (HMDI-MCs) demonstrate excellent dispersibility, tunable characteristics, and a high core material content of 93 wt%. Self-healing anti-corrosion coatings containing HMDI-MCs were prepared and underwent accelerated corrosion testing in sodium chloride (NaCl) solution. The result showed that HMDI is capable of leaking from microcapsules and undergoing solidification, thus forming a barrier to metal steel from corrosion hazards by endowing the coatings with effective self-healing abilities. This paper expands the application of the ES-IP technique in microencapsulation and suggests that HMDI-MCs have significant potential in self-healing anti-corrosion coating.

Bi-functional epoxy coating with long-term protection for Q235 steel prepared by incorporating melamine-grafted and carbon-black-modified graphene oxide

In recent years carbon materials, such as graphene oxide (GO) and carbon nanotube, have been became key materials for high-performance coatings for the protection of metals from corrosion. Here, a novel bi-functional epoxy coating was developed and formulated, which can replace traditional primers and topcoats. Furthermore, the effects of modified graphene oxide‑carbon black (MGC) on the corrosion resistance and weathering resistance of coated Q235 samples have been investigated using salt spray testing, UV accelerated aging testing, and electrochemical impedance spectroscopy. Results suggest that the incorporation of MGC leads to a considerable enhancement in the corrosion resistance and weathering resistance of coated samples. Notably, the bi-functional epoxy coating formulated with 0.2 wt% of MGC demonstrated the most effective anti-corrosion and weathering resistant properties. During the UV accelerated aging testing for 20 days, the low-frequency impedance modulus values of bi-functional epoxy coated samples were recorded to be 1.09 × 108 Ω·cm2, which is higher than pure epoxy coated samples (9.05 × 106 Ω·cm2). Also, the highest adhesion strength of bi-functional epoxy coated samples decreased from 2.51 MPa to 1.97 MPa. These observations suggest that the bi-functional epoxy maintained a significant portion of its adhesion strength even after undergoing UV accelerated aging, indicating its robustness and durability under such corrosion conditions.

Interatomic potentials for graphene reinforced metal composites: Optimal choice

Graphene reinforced metal matrix composites represent a promising class of materials for high-strength surface coatings because of their high strength and ductility. This study reports the application of different interatomic potentials to correctly describe the interaction between graphene and metals (Al, Cu, Ni, and Ti) by molecular dynamics. Both simple pair potentials, such as Lennard-Jones and Morse, and many-body potentials, such as bond order potential are applied for the simulation of a graphene/metal system at room temperature. Three different structures are considered: (i) graphene interacting with one metal atom; (ii) graphene interacting with a metal nanoparticle, and (iii) three-dimensional graphene network filled with metal nanoparticles. We first determine the potential energy that any graphene/metal system can reach during exposure at 300 K; then, we analyze the interaction dynamics for all considered systems and all potentials. A considerable difference in the interaction between metal nanoparticles with planar and folded graphene was found. For graphene/Ni, graphene/Cu, and graphene/Ti, the Lennard-Jones and Morse potentials provide accurate energetic and structural properties of the studied structures; they also describe interaction in the graphene/metal system in a similar way, at variance with bond-order potential. For graphene/Al, the Tersoff and Morse potentials describe the interaction better than Lennard-Jones. For the simulation of graphene/Me system, the optimal choice of the potential for different structures is of crucial importance. The presented analysis of the interatomic potentials appears to be promising for realistic and accurate simulations of graphene reinforced metal composites.

Bimodal nanomechanical performance of nanostructured Lu2Si2O7 environmental barrier coating

Lutetium disilicate (Lu2Si2O7) is considered a promising material for environmental barrier coatings because of its remarkable high-temperature stability and low thermal conductivity. In this study, nanostructured Lu2Si2O7 coating was prepared successfully using as-prepared feedstocks via atmospheric plasma spraying. The nanomechanical performance of the coating was studied. The results showed that the coating exhibited a bimodal nanomechanical performance attributed to the bimodal distribution of its microstructure; i.e., in the coating, the melted lamella exhibited higher elastic modulus and nanohardness, whereas the unmelted and semi-melted parts processed low elastic modulus and nanohardness. The elastic modulus and nanohardness of the coating were 143.438 ± 25.449 GPa and 9.239 ± 3.514 GPa, respectively. Furthermore, the elastic and plastic works were 9.018–14.752 nJ and 12.792–25.793 nJ, respectively. The average value of the microhardness dissipation parameter of the coating was 0.615, demonstrated that the remarkable wear resistance of the coating.

Investigation of the effects of rare earth element doping on the thermophysical properties of Gd2Zr2O7 by first principles

Gd2Zr2O7 is one of the most promising new generation of ceramic materials for high temperature thermal barrier coatings. However, it still has great potential of improving thermal and mechanical properties and contributing tobetter thermal cycling performance of the coating. Doping rare earth elements in Gd2Zr2O7 is an effective method to enhance its thermal and mechanical properties. In this paper, the first principles is used to calculate the thermophysical properties of doped Gd2Zr2O7 with 16 rare earth elements, including modulus of elasticity, Debye temperature, minimum high-temperature thermal conductivity, high temperature thermal expansion coefficient, and fracture toughness, by which all doped Gd2Zr2O7 ceramics were ranked using the entropy method. The results show that doping with Pr, Sm, Yb, and Nd showed superior comprehensive performance. Specially, (Gd0.875Pr0.125)2Zr2O7 has the lowest Young's modulus of 244 MPa, Pugh ratio of 0.53, Debye temperature of 523.4 K, thermal conductivity of 1.27 W/(m·K), and the largest coefficient of thermal expansion of 9.19 × 10−6 K−1, and (Gd0.875Ho0.125)2Zr2O7 has the highest fracture toughness of 2.21 MPa·m1/2.

In Situ Study on the Structural Evolution of Flexible Ionic Gel Sensors

With the development of society, the demand for smart coatings is increasing. The development of flexible strain sensors using block copolymer self-assembled ionic gel materials provides a promising method for promoting the development of smart coatings. The ionic liquid in the ionic part of the material is crucial for the performance of the sensor. In this study, the structural changes within FDA/dEAN (self-assembly of acrylated Pluronic F127 (F127-DA) in partially deuterated ethylammonium nitrate (dEAN)) triblock copolymer ionic gel during uniaxial tensile flow were characterized using an in situ SAXS technique. The results revealed that the characteristics of the responses of the ionic gel to strain resistance were intricately linked to the evolution of its microstructure during the tensile process. At low levels of strain, the face-centered cubic lattice arrangement of the micelles tended to remain unchanged. However, when subjected to higher strains, the molecular chains aligned along the stretching direction, resulting in a more ordered structure with reduced entropy. This alignment led to significant disruption in bridging structures within the material. Furthermore, this research explored the impact of the stretching rate on the relaxation process. It was observed that higher stretching rates led to decreases in the average relaxation time, indicating rate dependence in the microstructure’s behavior. These findings provide valuable insights into the behavior and performance of flexible strain sensors based on ionic gel materials in smart coatings.

Effective Utilization of Local Fiber Coating Materials for Enhanced Sensitivity in Temperature and Humidity Sensing Applications

Effective Utilization of Local Fiber Coating Materials for Enhanced Sensitivity in Temperature and Humidity Sensing Applications

Analysis of the Effect of Different Surface Preparation Methods on Corrosion Resistance and Adhesion Strength of ASTM A36 Steel Substrate with Surface Tolerant Epoxy Paint as Coating Material

Analysis of the Effect of Different Surface Preparation Methods on Corrosion Resistance and Adhesion Strength of ASTM A36 Steel Substrate with Surface Tolerant Epoxy Paint as Coating Material

Effect of various surface coating methods on surface roughness, micromorphological analysis and fluoride release from contemporary glass ionomer restorations.

To evaluate the effect of various surface coating methods on surface roughness, micromorphological analysis and fluoride release from contemporary resin-modified and conventional glass ionomer restorations. A total of 72 permanent human molars were used in this study. The teeth were randomly assigned into 2 groups according to type of restorative materials used; resin modified glass ionomer cement and conventional glass ionomer (SDI Limited. Bayswater Victoria, Australia). Each group was subdivided into 3 subgroups according to the application of coat material; Sub-group1: without application of coat; Sub-group2: manufacturer recommended coat was applied and sub-group3: customized (vaseline) coat was applied. Each group was then subdivided into two divisions according to the time of testing; immediate (after 24h) and delayed (after 6 months of storage). Three specimens from each sub-group were selected for surface roughness test (AFM) and another 3 specimens for the micromorphological analysis using scanning electron microscope (SEM). For the fluoride release test, a total of 60 cylindrical discs were used (n = 60). The discs were randomly split into 2 groups according to type of restorative materials used (n = 30); resin modified glass ionomer cement and conventional glass ionomer. Each group was subdivided into 3 subgroups (n = 10) according to the application of the coat material; Sub-group1: without application of coat; Sub-group2: with the manufacturer recommended coat and sub-group3: with application of customized (vaseline) coat. Data for each test was then collected, tabulated, were collected, tabulated, and tested for the normality with Shapiro-Wilk test. Based on the outcome of normality test, the significant effects of variables were assessed using appropriate statistical analysis testing methods. Regarding the data obtained from surface roughness test, Shapiro-Wilk test showed normal distribution pattern of all values (p > 0.05). Accordingly, Two-way ANOVA outcome showed that the 'type of restoration' or 'test time' had statistically significant effect on the AFM test (p < 0.05). Regarding Fluoride specific ion electrode test 2-way ANOVA followed by Least Significant Difference (LSD) Post-hoc test revealed significant difference among the groups (p < 0.05). It showed that SDI GIC group after 14 days of measurement had the highest mean of fluoride release (36.38 ± 3.16 PPM) and SDI RMGIC after 30 days of measurement had the second highest mean of fluoride release (43.28 ± 1.89 PPM). Finally, regarding the micromorphological analysis using SEM, a slight difference was observed between the studied groups. Based on the results of this study, various coatings enhance surface roughness in the initial 24h of restoration insertion. Different coat types seems that have no influence on fluoride release and the micromorphological features of the restoration/dentin interface.

Controllable preparation of YSZ-STHS in arc plasma spheroidization: Exploring the plasma flow characteristics' impact on powder quality

Yttria-stabilized zirconia hollow spherical powder (YSZ-HOSP) is a widely utilized ceramic material in thermal barrier coatings (TBCs). Within the category of YSZ-HOSP, yttria-stabilized zirconia spherical thin-walled hollow-shell powder (YSZ-STHS) displays immense potential for producing TBCs with minimal inter-lamellar porosity and cracks. Arc plasma torch equipped with flow-shaping nozzle shows promise for preparing YSZ-STHS. However, there is limited research on the impact of the nozzle geometry on plasma flow field characteristics and the resulting effect on the quality of YSZ-HOSP, particularly in terms of spheroidization ratio, hollow-shell powder ratio, and shell thickness. To achieve controllable preparation of YSZ-STHS in arc plasma spheroidization, this paper proposed a novel model for the formation of YSZ-HOSP under different plasma flow characteristics, including high-speed compressing flow field, intermediate-speed critical flow field, and low-speed expanding flow field. These different plasma flow characteristics were achieved by changing the nozzle diameter and investigated by both numerical simulation and experiments in terms of plasma flow characteristics, electro-thermal characteristics, and the quality of the YSZ-HOSP. Results reveal that YSZ-HOSP prepared with high-speed compressing flow field resulted in a low hollow-shell powder ratio, while low-speed expanding flow field led to an over-thick shell. Conversely, the intermediate-speed critical flow field demonstrates relatively high thermal efficiency and enthalpy, along with moderate jet temperature and velocity, resulting in YSZ-STHS with a spheroidization ratio of 96.6 %, a hollow-shell powder ratio of 92.5 %, and a mean shell thickness of 3.49 μm. Therefore, it is evident that manipulating plasma flow characteristics allows for the controlled preparation of YSZ-STHS.

Sustainable Coating Materials: Exploring the Influence of Adjuvants on Kaolinite Suspension with Insights from Five Local Mining Clays.

Herein, we presented a comprehensive case study on the kaolin suspension derived from mining powder, with a specific emphasis on its mineral constituents within the size range of 2-5 μm and its suitability in spray applications. We have systematically investigated the influence of adjuvants, existing in both organic molecules and polymers, on the sedimentation behavior of clay suspensions. The investigations included the analysis of turbidity, dispersion weight, pH, and surface charge as key parameters. Our findings revealed that the specific presence of PEG-PPG-PEG, PAA, and PSAMA had a notable effect on delaying the suspension of sedimentation by the actual sediment weight as well as enhancing the uniformity of clay coating by the reflection efficiency of coating materials in PPFD units. To enhance sustainability in coating materials, it was essential to elucidate the optimal amounts of adjuvants and the pH levels as they are closely related to the efficacy of tree-coated spraying and soil conditions.

Latest Implant Materials and Implant Coating Materials- A Narrative Review

Dental implant fittings are often made of a variety of materials. Titanium alloys, zirconium, PEEK, composite materials, 3D-printed materials, and biodegradable materials are a few of the most recent implant materials. A great deal of research is being done on implant surface coating materials, such as nanostructured materials and bioactive coatings, to improve the osseointegration of the implant with the bone.

Identification and recombinant expression of a cutinase from Papiliotrema laurentii that hydrolyzes natural and synthetic polyesters.

Given the multitude of extracellular enzymes at their disposal, many of which are designed to degrade nature's polymers (lignin, cutin, cellulose, etc.), fungi are adept at targeting synthetic polyesters with similar chemical composition. Microbial-influenced deterioration of xenobiotic polymeric surfaces is an area of interest for material scientists as these are important for the conservation of the underlying structural materials. Here, we describe the isolation and characterization of the Papiliotrema laurentii 5307AH (P. laurentii) cutinase, Plcut1. P. laurentii is basidiomycete yeast with the ability to disperse Impranil-DLN (Impranil), a colloidal polyester polyurethane, in agar plates. To test whether the fungal factor involved in this clearing was a secreted enzyme, we screened the ability of P. laurentii culture supernatants to disperse Impranil. Using size exclusion chromatography (SEC), we isolated fractions that contained Impranil-clearing activity. These fractions harbored a single ~22 kD band, which was excised and subjected to peptide sequencing. Homology searches using the peptide sequences identified, revealed that the protein Papla1 543643 (Plcut1) displays similarities to serine esterase and cutinase family of proteins. Biochemical assays using recombinant Plcut1 confirmed that this enzyme has the capability to hydrolyze Impranil, soluble esterase substrates, and apple cutin. Finally, we confirmed the presence of the Plcut1 in culture supernatants using a custom antibody that specifically recognizes this protein. The work shown here supports a major role for the Plcut1 in the fungal degradation of natural polyesters and xenobiotic polymer surfaces.IMPORTANCEFungi play a vital role in the execution of a broad range of biological processes that drive ecosystem function through production of a diverse arsenal of enzymes. However, the universal reactivity of these enzymes is a current problem for the built environment and the undesired degradation of polymeric materials in protective coatings. Here, we report the identification and characterization of a hydrolase from Papiliotrema laurentii 5307AH, an aircraft-derived fungal isolate found colonizing a biodeteriorated polymer-coated surface. We show that P. laurentii secretes a cutinase capable of hydrolyzing soluble esters as well as ester-based compounds forming solid surface coatings. These findings indicate that this fungus plays a significant role in biodeterioration through the production of a cutinase adept at degrading ester-based polymers, some of which form the backbone of protective surface coatings. The work shown here provides insights into the mechanisms employed by fungi to degrade xenobiotic polymers.

Preparation and Application of Degradable Lignin/Poly (Vinyl Alcohol) Polymers as Urea Slow-Release Coating Materials.

The massive amount of water-soluble urea used leads to nutrient loss and environmental pollution in both water and soil. The aim of this study was to develop a novel lignin-based slow-release envelope material that has essential nitrogen and sulfur elements for plants. After the amination reaction with a hydrolysate of yak hair keratin, the coating formulation was obtained by adding different loadings (2, 5, 8, 14 wt%) of aminated lignin (AL) to 5% polyvinyl alcohol (PVA) solution. These formulations were cast into films and characterized for their structure, thermal stability, and mechanical and physicochemical properties. The results showed that the PVA-AL (8%) formulation had good physical and chemical properties in terms of water absorption and mechanical properties, and it showed good degradation in soil with 51% weight loss after 45 days. It is suitable for use as a coating material for fertilizers. Through high-pressure spraying technology, enveloped urea particles with a PVA-AL (8%) solution were obtained, which showed good morphology and slow-release performance. Compared with urea, the highest urea release was only 96.4% after 30 days, conforming to Higuchi model, Ritger-Peppas model, and second-order dynamic model. The continuous nitrogen supply of PVA-AL coated urea to Brassica napus was verified by potting experiments. Therefore, the lignin-based composite can be used as a coating material to produce a new slow-release nitrogen fertilizer for sustainable crop production.

(Gd0.2Ho0.2Er0.2Yb0.2Lu0.2)2Si2O7 and (Sc0.2Ho0.2Er0.2Yb0.2Lu0.2)2Si2O7 high-entropy rare-earth disilicates as promising materials for environmental barrier coatings

The novel potential environmental barrier coating materials, two high-entropy rare earth disilicates (HEDs) (Gd0.2Ho0.2Er0.2Yb0.2Lu0.2)2Si2O7 and (Sc0.2Ho0.2Er0.2Yb0.2Lu0.2)2Si2O7 were prepared by the solid-phase method. Both the HEDs showed remarkable high-temperature phase stability and an appropriate thermal expansion coefficient (CTE) that matched that of SiCf/SiC. In addition, both the HEDs possessed above 20% lower thermal conductivity at 1000 °C (1.37 and 1.42 W·m−1·K−1, respectively) compared to traditional single-component rare earth disilicate material YbDS, and they also exhibited higher mechanical properties and good resistance to water vapour corrosion at 1300 °C. Moreover, the corresponding free-standing coatings obtained after deposition by atmospheric plasma spraying (APS) showed excellent resistance to CMAS corrosion, primarily because of the formation of an apatite layer.

Effect of Si addition on the microstructure and liquid lead-bismuth eutectic cavitation erosion behaviors of AlCrFeMoTi laser clade coatings

High entropy alloys exhibit high resistance to the lead-bismuth eutectic (LBE), making them promising candidate materials for protective coatings. However, improving their mechanical properties and resistance to cavitation erosion in flowing LBE environment remains a challenge. In this study, AlCrFeMoTi coatings were synthesized using laser cladding, and Si was added to enhance their resistance to cavitation erosion. The results showed that the AlCrFeMoTi coatings mainly contained FeMoTi and Fe-Cr phases. After the addition of Si, a single phase FeMoTi was formed. Moreover, Si increased the hardness of the coatings by 9.6%. After cavitation erosion in LBE at 500 ℃, cracks formed on the surface of the coatings and the main damage mechanism of the coating was lamellar spalling. The addition of Si inhibited crack propagation and reduced the erosion depth of the coatings by 43.5%. It can be attributed to the addition of Si makes the oxidation homogeneous and the strengthening of the single-phase.

Influence of doping elements on thermo-physical properties of co-doped strontium zirconate for potential thermal barrier coatings

Strontium zirconate is a promising material for thermal barrier coatings due to some excellent properties. New four co-doped strontium zirconate with lower thermal conductivity and higher thermal expansion coefficient were synthesized in this study. Sr(Zr0.9Y0.05Yb0.05)O2.95 (SZYYb) with the smallest difference in ionic radius and mass has lowest thermal diffusion coefficients mainly due to the effect of extrinsic phonon scattering mechanisms, including lattice distortion and grain size. The electronic structures of four co-doped SrZrO3 were analyzed by first-principles calculations. The findings suggested that the difference in bond strength caused by different doping affected the differences in the lattice constant, which led to the highest thermal expansion coefficient of SZYYb.

A Review on Tool Life in Coal Measures Rocks

Tungsten carbide inserts in rock drill bits are predominantly used in drilling rocks, particularly in mining industries. The research studies performed on drill bits have been limited to several factors such as collecting failure data of bit components from the field, conducting wear tests considering rock properties, and introducing new coated insert materials. The role of Artificial Intelligence (AI) and Machine Learning (ML) for the betterment of tool wear with real-time data is limited. The present study has offered an evaluative perspective of an essential industrial issue. In this review, a concept map presents a visual organization and representation of knowledge obtained during the study. Utilizing the propositions from the concept map, a brief review of the integrated concepts of researchers relating drill bits, failure data, numerical and statistical models, wear analysis, reliability assessment, and prerequisites in developing new materials have been discussed in the backdrop of the present study.

Evaporative Drying Induced Self-Assembly of Epicuticular Wax: A Biomimetic Approach in Tuning Surface Roughness.

Epicuticular wax is an example of a naturally created functional material that forms a layer on the outermost surface of plants with the objective to protect them from adverse environmental conditions, such as UV-solar radiation, uncontrolled water loss, microbial attacks, and so forth. Their functionalities are often attributed to the chemical composition of the wax as well as the physical structuration formed by the wax crystals on the surface. With this work, we present a simple, one-step biomimetic approach to replicate similar surface structures, on model substrate, using wax extracted from Euphorbia Cerifera (Candelilla wax). First, we describe formation of structured wax due to self-assembly induced by evaporative drying on quartz plates. Subsequently, we highlight the fundamental physical parameters required to tune the surface morphology. Our experiments reveal that it is possible to achieve considerably diverse surface morphologies depending on the solvent properties and deposition temperature. This diversity is due to the kinetics of recrystallization of wax during evaporation of solvent which, in turn, is primarily driven by the solubility of wax as well as evaporation rate of the solvent. Thus, the final morphology that we obtain is an interplay between recrystallization kinetics and solvent evaporation. Additionally, the degree of crystallinity of the structured films could also be tuned by solvent polarity. Surprisingly, X-ray diffraction indicates that the crystalline structure at the molecular level remains similar to that of bulk Candelilla wax. Our results provide fundamental insights into the replication of epicuticular wax films and identification of tuning parameters to obtain different surface morphologies with the same wax material for potential bioinspired multifunctional coatings in cosmetic applications.