Tribological properties of YSZ and YSZ/Ni-YSZ nanocomposite coatings prepared by electron beam physical vapour deposition

Metal-ceramic nanocomposite coatings have been applied to many industrial applications owing to their remarkable properties such as wear, corrosion and high temperature oxidation resistance than that of metals and alloys in high temperature environments. In this study, YSZ and Ni-YSZ nanocomposite coatings deposited by electron beam physical vapour deposition (EBPVD) for high temperature environments have been investigated. Initially friction and wear behaviour of YSZ coatings deposited at various substrate temperature were studied. Then the effect on wear response of Ni-YSZ nanocomposites with different Ni content were investigated using a ball-on-disc micro tribometer. The structural and tribochemical changes that occurred in the wear tracks of YSZ and Ni-YSZ coatings were investigated using field emission scanning electron microscopy and Raman spectroscopy. The results obtained on sliding wear and friction behaviour of these nanocomposite coatings suggest that 50 wt.% of Ni in YSZ nanocomposite provides good wear resistance behaviour than that of other coatings. Such an improvement in tribomechanical and wear performance of the nanocomposite coating could be attributed to the optimum amount of Ni which promotes the formation of NiO from Ni due to the frictional heat between nanocomposite coating and the sliding counter body in wear track as confirmed by Raman analysis.     

Compositional effects on the fouling resistance of fluorourethane coatings

Conclusions  A series of fluorinated polyurethane polymers have been prepared and characterized. Immersion experiments have been performed to determine the fouling-release effectiveness of the coatings. The surface energies of the films are between 12 mJ m⁻² to 33 mJ m⁻² and are controlled by the fluorine content of the polymer. These surface energies are well below the values shown by conventional alkyd, epoxy, vinyl, polyester, and polyurethane coatings (39 mJ m⁻² and 50 mJ m⁻²). Surface energy is not the dominant factor in determining the fouling- release behaviour of these coatings. Instead, measurements of the coating modulus, hardness, and glass transition temperature indicate that supple, soft polymers, with a high degree of mobility may display more effective fouling-release characteristics than more rigid, harder polymers below their glass transition temperatures. Surface roughness also appears to be a major factor in determining coating fouling-release behaviour. This work has demonstrated that marine organisms bind to fluorinated polyurethanes with significantly less strength than to the unfluorinated epoxy, vinyl and urethane resins which are now used with toxicants in marine coatings. However, this work has shown that these fluorinated polyurethanes are not sufficiently promising to merit further attention as non-toxic anti-fouling coatings for ship hulls. Fluorinated polyurethanes remain very attractive coatings for exterior and anti-corrosive service, especially in application requiring easy cleanability and resistance to sunlight, weather, and chemicals.     

Laser ablation behaviors of vacuum plasma sprayed ZrC-based coatings

ZrC, ZrC-30 vol% SiC, and ZrC-30 vol% TiC coatings were fabricated by vacuum plasma spray and the laser ablation behaviors were evaluated by a CO₂ laser beam under two heat fluxes (15.9 and 25.5 MW/m²). The phase compositions and microstructures of the coatings after ablation were investigated and the effect of SiC and TiC additives was analyzed. The results showed that the ZrC–SiC coating displayed better ablation resistance compared with the ZrC and ZrC–TiC coatings under 15.9 MW/m² heat flux. While the ZrC–TiC coating exhibited the improved ablation resistance under 25.5 MW/m² heat flux. The continuous and integral ZrO₂–SiO₂ scale provided protective effect for the ZrC–SiC coating. A liquid ZrO₂–TiO₂ layer which owned self-healing ability was formed for the ZrC–TiC coating in both heat fluxes. However, the state of the formed liquid, like amount, viscosity, evaporation, and decomposition, was influenced by the environment and was vital for the ablation resistance. This work might give a clue for designing ultrahigh-temperature ceramics as potential laser ablation–resistant coating materials.     

Repair of spline shaft by laser-cladding coarse TiC reinforced Ni-based coating: Process,microstructure and properties

To repair the surface defects of spline shaft and improve wear resistance, the coarse TiC reinforced Ni-based composite coatings were fabricated on the spline shaft surface by laser cladding with six types of precursors containing Ni45, coarse TiC, and fine TiN powder. The effects of ceramic content and fine TiN addition on the formability, microstructure, and mechanical properties of the coatings were studied comprehensively. In TiC reinforced Ni-based coatings 1–3 without fine TiN addition, the porosity decreased from 20.415 % to 0.571 % with the increase of TiC concentration. The coatings mainly consist of CrB, Cr7C3, Cr23C6, coarse TiC, and γ-Ni. With the addition of fine TiN, the length of the ceramic phases in coatings 1#–3# decreased slightly, while volume fraction and porosity increased. Moreover, the ring-shaped Ti (C, N) phases were also detected at the edges of both undissolved TiC and TiN particles, which improved the bonding force between ceramics and matrix. Besides, these ceramics inhibited the generation of columnar crystals and eliminated the heat-affected zone. The performance test results show that the coating 3# with 30 wt% TiC and 6 wt% TiN exhibits the best wear resistance despite slightly decreased hardness, and its friction coefficient of 0.409 and wear rate of 42.44 × 10⁻⁶ mm³ N⁻¹·m⁻¹ are, respectively, 0.667 and 0.307 times those of the substrate. Based on the additive/subtractive hybrid manufacturing technology, the optimized coatings were ground to obtain the finishing surface, which indicates that the coarse TiC reinforced coating can be employed in repairing the damaged parts.     

Effect of pore content and pH on the corrosion behavior of hydrophobic ceramic coatings

In this paper, superhydrophobic ceramic coatings were successfully prepared on stainless steel substrates (S304) by sol–gel method, and the effects of pore content and pH conditions on the corrosion resistance of hydrophobic ceramic coatings were studied. As the porosity increases, the contact angle of the coating increases. Among them, the contact angles of the coatings with 15% and 20% porosity in different pH solutions are all greater than 150°, achieving superhydrophobic surfaces. The contact angle results before and after corrosion show that the solution with a higher pH has a greater damage to the hydrophobicity of the coating. The corrosion resistance of the coatings was evaluated comparatively from polarization curves and electrochemical impedance spectroscopy. As the hydrophobicity improves, the corrosion resistance of the hydrophobic ceramic coating is enhanced. The impedance moduli at .01 Hz of the coating are 1.04 × 10³ times (pH 4), .13 × 10³ times (pH 7), and .74 × 10³ times (pH 10) of the bare steel, respectively. With the increase of pH, the corrosion resistance of hydrophobic ceramic coatings decreases, because OH⁻ in the corrosion solution is more easily adsorbed on the surface of the coating, thereby destroying the long hydrophobic chains.     

New approach for simultaneous enhancement of anticorrosive and mechanical properties of coatings: Application of water repellent nano CaCO3–PANI emulsion nanocomposite in alkyd resin

New alkyd coatings were prepared by addition of water-based polyaniline–4% CaCO₃ (PAC) nanocomposites into alkyd resin. Pure polyaniline (PANI) and PAC were synthesized using ultrasound assisted emulsion polymerization and added to alkyd resin to form nanocomposite coating. Nano CaCO₃ was added in different percentage ranging from 0% to 8% of monomer during the synthesis of polyaniline. XRD and TEM reveals that water repellent nano CaCO₃ is thoroughly dispersed in PANI matrix. The effect of PANI and PAC nanocomposite on mechanical and anticorrosion performance of alkyd coating was evaluated. An electrochemical measurement (Tafel Plots) shows that corrosion current I_corr was decreased from 0.89 to 0.03 μA/cm², when PAC nanocomposite was added to neat coatings. Positive shift of E_corr. also indicates that PAC nanocomposite acts as an anticorrosive additive to alkyd coating. Presence of water repellant nano CaCO₃ in PAC nanocomposite has exhibited dual effect, such as improvement in mechanical and anticorrosion properties. The experimental results have shown superiority of PAC nanocomposite over PANI when PAC nanocomposite added to alkyd coatings.     

UV-polymerisable,phosphorus-containing,flame-retardant surface coatings for glass fibre-reinforced epoxy composites

A vinyl phosphonic acid based flame retardant coating has been applied on the surface of a glass-fibre reinforced epoxy (GRE) composite substrate using a UV polymerisation technique. On exposure to heat the poly (vinyl phosphonic acid) (PVPA) coating thus obtained, intumesces and acts as a thermal insulator, providing active fire protection to the composite structure. Samples with ∼300 and 500 μm thick coatings were prepared. The fire performance of the coated GRE composite was studied by cone calorimetry at 35 and 50 kW/m² heat fluxes. While the sample with ∼500 μm thick coating did not ignite at both heat fluxes, the one with the ∼300 μm thick coating ignited at 50 kW/m², however the time-to-ignition was delayed from 60 s in the uncoated sample to 195 s and the peak heat release rate reduced from 572 kW/m² to 86 kW/m². The coatings did not peel off when subjected to a tape pull test and resisted cracking/debonding during an impact drop test of up to 5 J energy. However, the coatings are hydrophilic, showing significant mass loss in a water soak test. The improvement of the hydrophobicity of these coatings is a focus of our future research.     

Preparation and investigation of pulse co-deposited duplex nanoparticles reinforced Ni-Mo coatings under different electrodeposition parameters

In this work, Ni–Mo–SiC–TiN nanocomposite coatings were deposited on aluminium alloy by pulse electrodeposition with various electrodeposition parameters. The influences of the pulse frequency and duty cycle on the phase structure, morphology, mechanical and corrosion performance of the coatings were systematically investigated. The results showed that with increasing pulse frequency and decreasing duty cycle, the content of embedded duplex nanoparticles increased, and the grains refined gradually. The nanocomposite coating that was prepared at 20% duty cycle and 1000 Hz pulse frequency exhibited compact, uniform, and fine microstructures with the maximum incorporation of nanoparticles (6.81 wt% TiN and 1.72 wt% SiC). The wear rate and average friction coefficient then declined to 4.812 × 10^?4 mm³/N·m and 0.13, respectively, with a maximum microhardness of 519 HV. Simultaneously, the corrosion current density was reduced to 3.11 μA/cm², and a maximum impedance of 34888 Ω cm² was exhibited. The uniformly distributed duplex nanoparticles acted as a hindrance, which consequently supported the enhancement of corrosion and wear resistance. By investigating the variation of the pulse diffusion layer with electrical parameters, it was discovered that when the crystallite size is equivalent to or smaller than the diffusion layer thickness, it would be easier to cross the diffusion layer to incorporate in the coating. Additionally, the effects of various duty cycles and pulse frequencies on the nucleation process of the grains were discussed.     

Investigation of the corrosion protection behavior of natural montmorillonite clay/bitumen nanocomposite coatings

The influence of clay particles on the corrosion properties of bituminous coating was studied. Different percentages of natural montmorillonite clay (Cloisite Na⁺) were added to emulsified bitumen in water to make 2 wt.%, 3 wt.% and 4 wt.% of clay/bitumen nanocomposite coatings. The coatings were applied on steel 37. Optical microscopy and transmission electron microscopy (TEM) were employed to study the structure of nanocomposite. To investigate the anti-corrosion properties of the coated panels, electrochemical impedance spectroscopy (EIS) was used. The findings indicated that the addition of clay nanolayers improved corrosion resistance of the coatings. Moreover, increasing clay loading up to 4 wt.%, increased the corrosion resistance.     

Preparation and characterization of thermally stable epoxy-titanate coatings

Epoxy-polyamide coatings are used to protect metallic substrates in corrosive atmosphere. Thermal stability of the coating can be improved by the addition of inorganic cross-linking agent. Epoxy resin is incorporated with small percentage of silicone resin and cured with two types of hardeners such as polyamide and butyl titanate. The physical properties, heat resistance properties and electrochemical impedance behaviour of these coatings on steel in 0.5 M NaCl solution have been studied. The result implies that the heat resistant character of the titanate-cured coating is increased from 260 to 370 °C. The impedance study has shown that the coating resistance exerted by both the systems is in the range of 10⁵ Ω cm² after 6 days of immersion in 0.5 M NaCl. FTIR and Raman spectroscopy analysis confirm the presence of titanate linkage in the cured polymer coating. Thermal stability data indicate that the epoxy silicone resin cured with titanate hardener possesses higher thermal stability than that cured by polyamide hardener.     

Thermostability,oxidation, and high-temperature tribological properties of nano-multilayered AlCrSiN/VN coatings

In this study, monolithic AlCrSiN, VN, and nano-multilayered AlCrSiN/VN coatings were deposited using a hybrid deposition system combining arc ion plating and pulsed direct current magnetron sputtering. The microstructure, thermostability, mechanical, oxidation and tribological properties of the coatings were comparably investigated. The multilayered AlCrSiN/VN coating exhibited a face-centered cubic (fcc) structure with (200) preferred orientation and showed the highest hardness (30.7 ± 0.5 GPa) among these three coatings due to the multilayer interface enhancement mechanism and higher compressive stress. The AlCrSiN sublayers effectively prevented the V element from rapid outward diffusion to the surface of AlCrSiN/VN coating at elevated temperatures, which improved the oxidation resistance of the coating. Decomposition of V (Cr)–N bonds occurred at annealing temperatures from 800 °C to 1000 °C and V₂N phase appeared at 1100 °C. The AlCrSiN/VN coating showed excellent tribological performance at high temperatures by combining the merits of VN layers for low friction coefficient and AlCrSiN layers for superior oxidation resistance. Compared to VN and AlCrSiN coatings, AlCrSiN/VN coating showed the lowest wear rate of 2.6×10^-15 m³/N·m at 600 °C and lowest friction coefficient of 0.26 at 800 °C with a relativity low wear rate of 39.4×10^-15 m³/N·m.     

The microstructural features and corrosion behavior of Hydroxyapatite/ZnO nanocomposite electrodeposit on NiTi alloy: Effect of current density

In the present study, hydroxyapatite/ZnO nanocomposite coatings were developed on NiTi superelastic alloy via pulse electrodeposition technique under three different current densities. The morphological observations (FESEM) indicated that under 6 mA/cm², a compact, uniform composite layer could form, whereas lower or higher current densities resulted in non-uniform, porous coatings with uneven distribution of nanoparticles. XRD and FTIR studies revealed that pure hydroxyapatite was not achieved below 6 mA/cm². Topographic features (AFM) were assessed and demonstrated a continuous rise in roughness parameters as current density increased. The corrosion behavior was investigated through potentiodynamic polarization as well as impedance spectroscopy techniques. According to the extracted data, the porosity and non-uniformity of coatings formed under 3 and 9 mA/cm² caused a detrimental effect on the corrosion resistance of surfaces. The layer obtained under 6 mA/cm² showed resistance (R_c) which was almost two times greater than those deposited under 3 and 9 mA/cm² current densities. Last but not least, the bioactivity of coatings was evaluated in simulated body fluid. It was observed that more compact deposits offered more active sites for apatite nucleation, resulting in refined cauliflower-like grains. Accordingly, it can be asserted that the best composite coating was achieved under 6 mA/cm² current density.     

Aging effect on microstructure and property of strontium zirconate coating co-doped with double rare-earth oxides

Strontium zirconate coating co-doped with ytterbia and gadolinia (Sr(Zr_0.9Yb_0.05Gd_0.05)O_2.95, SZYG) and strontium zirconate coating (SrZrO₃, SZ) were prepared by atmospheric plasma spraying. The SZYG coating shows improved phase stability from room temperature to 1400°C, while its thermal conductivity (~0.8 W m⁻¹K⁻¹) is at least ~40% lower than that of the SZ coating. Both SZYG and SZ coatings were heat-treated at 1400°C up to 360 hours in air. The X-ray diffraction results reveal that both the as-sprayed SZYG and SZ coatings are composed of main phase SrZrO₃ and secondary phase t-ZrO₂. These two phases do not undergo phase transition upon heat treatment up to 360 hours in the SZYG coating, whereas t-ZrO₂ transforms into m-ZrO₂ almost completely after 20 hours heat treatment in the SZ coating, suggesting a strong promoting role in stabilizing t-ZrO₂ by the additions of Yb₂O₃ and Gd₂O₃ in the SZYG coating. The content of t-ZrO₂ is ~4.3 wt.% in the as-sprayed SZYG coating and increases to ~19.5 wt.% after 360 hours heat treatment, analyzed using Jade software. The thermal expansion coefficients (TECs) of the SZYG coatings have no abrupt decrease after heat treatment for more than 5 hours, whereas an abrupt decrease in the TECs of the SZ coating is observed after 100 hours heat treatment. The superior performance of the SZYG coating is attributed to the very stable secondary phase t-ZrO₂ stabilized by the co-doping of ytterbia and gadolinia.     

Chemical synthesis of TiO2 nanoparticles and their inclusion in Ni–P electroless coatings

The work addresses the preparation of Ni3P3TiO₂ nanocomposite coatings on mild steel substrate by the electroless technique. Nanosized TiO₂ particles were first synthesized by the precipitation method and then were codeposited (4 g/l) into the Ni3P matrix using alkaline hypophosphite reduced EL bath. The surface morphology, particle size, elemental composition and phase analysis of as-synthesized TiO₂ nanoparticles and the coatings were characterized by field emission scanning electron microscopy (FESEM), energy-dispersive analysis of X-ray (EDAX) and X-ray diffraction (XRD). Coatings with 20 µm thickness were heat treated at 400 °C for 1 h in argon atmosphere. The morphology, microhardness, wear resistance and friction coefficient characteristics (ball on disc) of electroless Ni3P3TiO₂ nanocomposite coatings were determined and compared with Ni3P coatings. The results show that as-synthesized TiO₂ nanoparticles are spherical in shape with a size of about12 nm. After heat treatment, the microhardness and wear resistance of the coatings are improved significantly. Superior microhardness and wear resistance are observed for Ni3P3TiO₂ nanocomposite coatings over Ni3P coatings.     

Microstructure,mechanical, tribological,and oxidizing properties of AlCrSiN/AlCrVN/AlCrNbN multilayer coatings with different modulated thicknesses

Multilayer structure design is one of the most promising methods for improving the comprehensive performance of AlCrN-based hard coatings applied to cutting tools. In this study, four types of AlCrSiN/AlCrVN/AlCrNbN multilayer coatings, with different modulated thicknesses, were deposited to investigate their microstructure, mechanical, tribological, and oxidizing properties. All multilayer coatings exhibited grain growth along the crystallographic plane of (200) with a NaCl-type face-centered cubic (FCC) structure. The results show that, as the modulation thickness decreases from ～35 nm to ～10 nm, (1) the grain refinement effect is increasingly evident; (2) all multilayer coatings show a hardness of >30 GPa and an elastic modulus of >300 GPa. Both the ability to resist elastic strain to failure and the plastic deformation of multilayer coatings increase. In addition, their resistance to cracking reduces; (3) the wear rates of these multilayer coatings reduce successively from 1.78 × 10^?16 m³ N^?1 m^?1 to 7.7 × 10^?17 m³ N^?1 m^?1. This is attributed to an increase in self-lubricating VO_x and a decrease in adhesives from the counterparts; (4) the best high-temperature oxidation resistance was obtained for the multilayer coating with a modulated thickness of ～15 nm.     

Influence of cobalt on manganese incorporation in Ni–Co coatings

The effect of alloying <1 wt% Mn with plain Ni, Ni–Co alloys and plain Co coatings in terms of the structure and properties has been studied. The alloys were electrodeposited from an additive free sulphamate electrolyte. The Mn concentration in the electrolyte was maintained at 5 g L⁻¹ so as to obtain <1 wt% Mn content in the alloy coatings. The Energy Dispersive X-ray analysis (EDX) showed that the Mn content reduced from 0.97 to 0.05 wt% with increase in Co content from 0 to 98 wt% in the alloy coating. An increase in microhardness was obtained on the addition of Mn to Ni/Ni–Co alloys. The X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) studies revealed a change in crystal structure and morphology. Pin-on-disc tribology test revealed better wear performance of Ni–18 wt%Co–Mn alloy coating compared to the other Ni–Mn/Ni–Co–Mn alloy coatings.     

Al2O3/Si3N4 nanocomposite coating on aluminum alloy by the anodizing route: Fabrication,characterization, mechanical properties and electrochemical behavior

An Al₂O₃/Si₃N₄ nanocomposite coating was successfully fabricated on commercial aluminum alloy. Hardness measurements, polarization and electrochemical impedance spectroscopy (EIS) were employed to study the mechanical and corrosion behaviors of the coatings. Field-Emission Scanning Electron Microscopy (FE-SEM) equipped with Energy Dispersive Spectroscopy (EDS) and X-ray diffraction (XRD) were utilized to characterize the surface morphology and phase composition of the coatings. Also, coatings abrasive wear properties were evaluated with a modified ASTM G105 standard. FE-SEM image, EDS and XRD analysis revealed the presence of Si₃N₄ in the coating. Furthermore, the results showed hardness of the coatings to increase from 380±50 HV for the anodized layer to 712±36 HV for the composite coatings that were formed in an electrolyte containing 6 gr/lit Si₃N₄ nanoparticles. Electrochemical measurements indicated that corrosion resistance of the nanocomposite coating significantly increased compared to the anodized coating. In addition, the effect of Si₃N₄ nanoparticles into the nanocomposite coatings on abrasive wear mechanism and mass loss rate of the coatings was investigated.     

Effects of heat treatment on microstructure and mechanical properties of TiC/TiB composite bioinert ceramic coatings in-situ synthesized by laser cladding on Ti6Al4V

To improve the wear resistance of titanium alloy, in this work, TiC/TiB composite bioinert ceramic coatings were synthesized in-situ via laser cladding using Ti and B₄C mixed powders as precursor materials. And to decrease the impact of the excessive residual tensile stress generated by the uneven temperature distribution on the performance of coatings, the coatings were then subsequently heated for 3 h at different temperatures (400 °C, 600 °C, and 800 °C) and then air cooled. The effects of heat treatment on the microstructure, residual stress, micro-hardness, fracture toughness, and wear resistance of the coatings were investigated. The results showed that phase compositions and microstructure of the heat-treated coatings were virtually identical to that of the untreated coatings; however, the precipitation of acicular TiB enhanced mechanical properties of the heat-treated coatings. In addition, the average residual tensile stress values of the coatings decreased as the heat treatment temperature increased, which improved fracture toughness of the coatings from 3.95 to 4.68 MPa m^1/2. Moreover, wear resistance of the coatings was greatly enhanced by heat treatment; as the wear volume of the heat-treated coatings decreased by 50% at 800 °C compared with that of the untreated coatings. Lastly, the coatings showed good biocompatibility after being evaluated in vitro, and therefore had broad application prospects in the field of orthopedic implants.     

Thick thermal barrier coatings with different segmentation crack densities: Microstructure analysis and thermal oxidation behavior

Thick thermal barrier coatings (TTBCs) have been developed to increase the lifetime of hot section parts in gas turbines by increasing the thermal insulating function. The premeditated forming of segmentation cracks was found to be a valuable way for such an aim without adding a new layer. The TTBC introduced in the current study are coatings with nominal thickness ranging from 1 to 1.1 consisting of MCrAlY bond coat and 8YSZ top coat deposited by air plasma spray technique (APS). TTBCs with segmented crack densities of 0.65 mm^?1 (type-A) and 1 mm^?1 (type-B) were deposited on a superalloy substrate by adjusting the coating conditions. It was found that the substrate temperature has an influential role in creating the segmentation crack density. The crack density was found to increase with substrate temperature and liquid splat temperature. The two types of coatings (type-A and B) with different densities of segmentation crack were heat-treated at 1000 °C (up to 100 h) and 1100 °C (up to 500 h). The variation of hardness measured by indentation testing indicates a similar trend in both types of coatings after heat treatments at 1000 °C and 1100 °C. Weibull analysis of results demonstrates that higher preheating coating during the deposition results in a denser YSZ coating. The growth rate of TGO for TTBCs was evaluated for cyclic and isothermal oxidation routes at 1000 °C and 1100 °C. The TGO shows the parabolic trend for both two types of coatings. The Kps value for two oxidation types is between 5.84 × 10^?17 m²/s and 6.81 × 10^?17 m²/s. Besides, the type B coating endures a lifetime of more than 40 cycles at thermal cycling at 1000 °C.     

Characterization of polyurethane foam as heat seal coating in medical pouch packaging application

In this study the use of polyurethane foam (PUF) as a heat seal coating for potential application in medical pouch packaging were investigated. We prepared PUF coatings at various foam densities and cell densities through mechanical foaming at various stirring speeds; then used a LUMisizer to examine their stabilities. After applying PUF coatings of various foam densities onto a medical packaging material (Tyvek?) at various thicknesses, then employed impulse heat sealing with linear low density polyethylene (LLDPE) films to fabricate medical pouches. In addition to investigating the morphology, tack properties, adhesion, scratch resistance, flexibility, and durability of the PUF coats, the peel strength and air permeability of the medical pouches were also measured. Increasing the foam density of the PUF coatings increased their stability; the PUF coats prepared at a higher foam density exhibited greater tackiness (<1 g/cm²), adhesion (5B), scratch resistance (HB), flexibility (passes), and durability (ΔYI ≤ 5). The peel strength measured in the T-peel configuration increased upon increasing the foam density and decreasing the coating thickness of the PUF coat/LLDPE pouches. The air permeability of the pouches increased upon increasing the foam density and cell density of the PUF coat/LLDPE pouches. Morphological studies using scanning electron microscopy were consistent with the experimental results.