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Smart polymeric coatings play a crucial role in protecting steel surfaces from corrosion and wear. One of progressive smart behavior is self-healing behavior especially in self-healing epoxy coatings. Creating or improving the second smart behavior is known as a new trend for these smart materials. This study aims to investigate the effects of ZrO 2 nanoparticles on the self-lubricating behavior as the second smart behavior of the linseed oil-loaded microcapsule/epoxy composite coatings. To do so, the in-situ polymerization method was used for the synthesis of linseed oil-loaded microcapsule. Results showed that the average size of prepared linseed oil-loaded microcapsules was 563 nm. The composite coatings were prepared by different content of ZrO 2 nanoparticles (0, 3, 6, 9, 12, and 15 wt%) and constant content of linseed oil-loaded microcapsules (5 wt%). The tribological performance of samples was studied using pin-on-disk test. The worn surface of the samples was also studied using field emission scanning electron microscope (FESEM) images. Results proved that the frictional coefficient and wear rate of the samples were significantly decreased by increasing the concentrations of the ZrO 2 nanoparticles up to 9 wt%. The lowest friction coefficient and wear rate values of 0.085 and 0.142 × 10−6 mm3/Nm were obtained for 5 wt% linseed oil-loaded microcapsules/epoxy with 9 wt% ZrO 2 which were about 82 % and 88 % lower than those of pure epoxy coating. [ABSTRACT FROM AUTHOR]

Zirconium oxide(ZrO2) is an important ceramic material characterized by a wide optical bandgap, low optical losses, high dielectric constant, excellent physical and structural properties, high coefficient of thermal expansion and chemical stability. This paper reports the synthesis of ZrO2 nanoparticles by the sol–gel method using ZrO(NO3)2 as the zirconium precursor and ammonia solution (25%) as the precipitating agent. The pH value of the sol and the annealing temperature strongly influence the morphology and size of nanoparticles. In the present work, the sol pH was varied from 8 to 11 and the nanoparticles obtained were annealed in the temperature range of 400–700°C. The structural, morphological and optical properties of the nanoparticles were investigated using x-ray diffraction, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy and photoluminescence measurements. The results demonstrate that the stable t-ZrO2 phase starts appearing above 400°C, with nanoparticle size varying in the range of 15–22 nm. The optimal size of ZrO2 nanoparticles (15.65 nm) was obtained at a pH value of 9 and an annealing temperature of 500°C. [ABSTRACT FROM AUTHOR]

The progress in tribocorrosion performance of the engineering parts is in dire need of improving their surface properties. In the present contribution, Ni-Cr-ZrO2 layers were electrodeposited on St37 steel. The stress was put on optimizing the process factors, including the parameters involved in pulsed current electrodeposition and level of the ZrO2 reinforcing nanoparticles (0–20 g/L) in the bath. The surface characteristics of the electrodeposits were evaluated using FESEM, EDS, AFM, and XRD. The tribomechanical characteristics of the films were determined using a Vickers microhardness tester and pin-on-disk apparatus. The electrochemical behavior of the samples was studied using OCP, EIS, PDP, and immersion techniques. The results demonstrated that the included ZrO2 nanoparticles led to more homogenous, rougher, and defect-free surfaces, while they did not change the phase composition of the alloy electrodeposits. The polarization resistance of the Ni-Cr alloy coating increases by 6.7 times when 10 g/L of the reinforcing nanoparticles is added to the electrolyte. A decrease of ≈42 % in the mean COF value was obtained by the incorporation of 10 g/L ZrO2 nanoparticles into the plating bath. The coating system developed holds the promise to address both technical requirements and health concerns.

This study aimed to evaluate the influence of denture cleansers on the color, stability, and surface roughness of three-dimensional (3D)-printed denture base resins modified with zirconium dioxide nanoparticles (nano-ZrO2). A total of 440 specimens were fabricated using one heat-polymerized resin, and two 3D-printed resins (NextDent and ASIGA). According to the nano-ZrO2 content, the specimens for each resin were divided into five groups (0%, 0.5%wt, 1%wt, 3%wt, and 5%wt). Each concentration was divided into four subgroups (n = 10) based on the immersion solution (distilled water, sodium hypochlorite, Corega, and Fittydent) and immersion duration (360 and 720 days). The color changes (∆E00) and surface roughness (Ra, µm) of each specimen were measured at different time intervals (base line, 360 days, 720 days) using a spectrophotometer and a non-contact profilometer, respectively. The results were statistically analyzed using ANOVA and a post hoc Tukey's test (α = 0.05). Sodium hypochlorite showed the highest significant color change of all the denture base resins (p < 0.001). The average value of ΔE00 for sodium hypochlorite was significantly higher than the values for the other solutions (Fittydent, Corega, and water) (p < 0.001). Color stability was significantly affected by immersion time for all types of solutions except Corega (p < 0.001). All of the tested immersion solutions (distilled water, sodium hypochlorite, Corega, and Fittydent) showed a significant increase in the surface roughness of all the denture base resins (p < 0.05). Surface roughness was substantially increased by immersion time for all types of solution except Fittydent (p < 0.001). Denture cleansers can result in substantial color change and affect the surface roughness of unmodified and nanoparticle-modified denture base resins. Therefore, the selection of denture cleanser and appropriate types of material is critical for denture longevity. [ABSTRACT FROM AUTHOR]

Magnesium alloys with a strengthening long-period stacking ordered structure (LPSO-phase) offer outstanding mechanical properties, but their low corrosion resistance necessitates additional surface protection. The work investigates the influence of adding ZrO2 nanoparticles at a concentration of 1–4 g/l to the electrolyte on the thickness, structure, composition, wettability, and anticorrosion properties of oxide layers formed during plasma electrolytic oxidation (PEO) of the Mg97Y2Zn1 alloy with the LPSO-phase. It was found that during PEO, under the influence of an electric field, ZrO2 nanoparticles penetrate into the forming oxide layer and reduce its porosity. The study revealed a decrease in the quantity and size of pores near the barrier layer in places where the alloy LPSO-phase comes out to the interface with the oxide layer. Low concentrations of ZrO2 nanoparticles (1–2 g/l) reduce the corrosion rate of the alloy up to two times compared to the base case. The minimum corrosion current density icorr≈14 nA/cm2 and the highest polarization resistance Rp≈2.6 MΩ•cm2 are found in the sample formed in an electrolyte with the addition of 1 g/l of ZrO2 nanoparticles. Calculation of the barrier zone parameters of oxide layers showed that an increase in the ZrO2 concentration in the electrolyte leads to an increase in the barrier layer thickness and in its specific conductivity, which negatively affects the corrosion resistance of the formed oxide layers – the barrier zone resistance of the layer obtained by adding 4 g/l of ZrO2, drops by ~20 % compared to the base case (up to ~1 MΩ•cm2).

This article explores the synthesis and characterization of ZrO2 nanoparticles for gas sensing purposes. The researchers utilized a co-precipitation technique to create the nanoparticles and examined their structural, particle size, UV-visible, and gas sensing properties. The findings indicate that the crystal structure and size of the nanoparticles vary depending on the sintering temperature. The nanoparticles demonstrated sensitivity to acetone and methanol, with a greater sensitivity to acetone. The study emphasizes the potential of ZrO2 nanoparticles for gas sensing applications and their distinct properties compared to bulk ZrO2. Further research is recommended to investigate the sensing capabilities of ZrO2 nanoparticles for industrial gases. [Extracted from the article]

This study investigated the influence of three different frequencies (100, 1000, and 2000 Hz) during the PEO process on the characteristics of ceramic coatings fabricated on Ti-6Al-4V alloys in the presence of 12 g/L Na3PO4.12H2O and 3 g/L ZrO2 nanoparticles. The microstructure, surface roughness, wettability, chemical composition, and corrosion performance of the coatings were thoroughly examined to assess their performance. The microstructural results revealed that increasing frequencies led to a reduction in the porosity size, as well as a decrease in coating thickness, wettability, and surface roughness. Additionally, the corrosion performance of the coatings was evaluated in Hank's solution using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) methods. As the frequency rose from 100 to 2000 Hz, the corrosion current density dropped significantly from 47.35 to 13.75 nA/cm2 and the corrosion potential increased from 218 to 684 mV versus Ag/AgCl electrode. These findings indicated that the coating produced at a frequency of 2000 Hz exhibited the lowest corrosion density, thereby demonstrating superior corrosion resistance compared to the coatings produced at lower frequencies. The corrosion resistance of the optimum coating (coating formed at a frequency of 2000 Hz) was found to be approximately 0.8 times higher compared to the uncoated metal. [ABSTRACT FROM AUTHOR]

Recently, many studies have increasingly dedicated have paid considerable attention to how nanofluids affect the efficiency of renewable energy systems. In this study, the effectiveness of ZrO2–distilled water (DW) nanofluid effectiveness on a solar thermal collector (FPSC) in Hungary, Gödöllő, was studied. First, four different volume fractions of 20 nm ZrO2 nanoparticles (0.025 %, 0.05 %, 0.075 % and 0.1 %) were added to DW-based nanofluids, and the stability and nanofluids characteristics were examined using various measurement instruments. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and field-emission scanning electron microscopy (FESEM), were used in the analysis of structural and morphological characteristics. The efficiency of a solar collector powered via nanofluids was then examined at various flow rates: 0.025, 0.033 and 0.041 kg/s. Findings showed that adding nanoparticles improved the FPSC’s efficiency to 72.1 %, and thermal efficiency of the FPSC increased by 26.2 % relative to that of water at 0.1% concentration and 0.041 kg/s flow. The proposed FPSC system in the nanofluid showed greater exergy efficiency than the system in DW, and a considerable in exergy efficiency (∼16.05 %) was observed when the nanoparticle concentration in the working fluid was 0.1 % ZrO2–DW. The system yielded maximum exergy efficiency. This study demonstrated the significant potential of ZrO2 nanoparticles for the application of solar energy.

Objective: to investigate and compare the reinforcing effects of glass fibers (GFs) and ZrO2 nanoparticles at different ratios on the Flexural Strength (FS), Microhardness (MH), and Surface Roughness (SR) of autopolymerizing provisional PMMA. Methods: A total of one hundred and twenty specimens of autopolymerizing PMMA were prepared for FS, MH, and SR tests and grouped as follows: no additives (control group), for the tested groups, different ratios of GFs and ZrO2 at 5% of autopolymerizing PMMA were incorporated. The ratios of GFs/ZrO2 nanoparticles were 0%-5%, 1%-4%, 2%-3%, 2.5%-2.5%, 3%-2%, 4%-1% and 5%-0% (n = 5). The FS was evaluated using the three-point bending test, MH was evaluated using the Vickers microhardness tester and SR was evaluated using a contact-type profilometer. Data were analyzed using ANOVA, Tukey’s test, and Person correlation at 0.05 level of significance. Results: The unreinforced group had the lowest FS, MH, and SR mean values followed by (0%GFs + 5% ZrO2), (1% GFs + 4% ZrO2), (2% GFs + 3% ZrO2), (2.5% GFs + 2.5% ZrO2), (3% GFs + 2% ZrO2), (4% GFs + 1% ZrO2) and (5% GFs + 0% ZrO2) which had the highest values. Conclusion: Hybrid reinforcement with GFs, ZrO2 nanoparticles, or a combination of them effectively improved flexural strength and microhardness of autopolymerizing provisional PMMA that would create provisional restorations with extended clinical service. GFs demonstrated superior reinforcing effects compared to ZrO2 nanoparticles. However, reinforcement with 2.5–5% GFs increased the surface roughness for provisional restoration.

TiO2 oxide coatings incorporated ZrO2 nanoparticles were prepared on Cp-Ti using the plasma electrolytic oxidation (PEO) process in electrolyte solutions containing dispersed ZrO2 nanoparticles. The coatings’ microstructure, roughness, and composition were characterized using scanning electron microscopy (SEM), roughness profilometry, and X-ray diffractometry (XRD) analyses, respectively. The coatings’ friction and wear characteristics were examined using a ball-on-disk sliding test in a simulated body fluid (SBF) electrolyte. The as-prepared oxide coatings had a rough and porous surface structure, primarily consisting of rutile and/or anatase TiO2, tetragonal ZrO2, and ZrTiO4. ZrO2 nanoparticles were incorporated into the TiO2 coating layers and were found on the surface or in the pores. The wear and friction behavior of the oxide coatings were influenced by the quantity of ZrO2 nanoparticles (1 g/L, 3 g/L, and 5 g/L) in the electrolyte solution. The wear resistance of coatings improved by decreasing the wear rate by about 8 % (from 2.31 × 10−6 mm3/Nm to 2.11 × 10−6 mm3/Nm) when the ZrO2 nanoparticles concentration in the electrolyte solution rose from 1 g/L to 5 g/L, because of the formation of more of harder ZrO2 and ZrTiO4 phases in the coatings.

The materials tribology community has identified that the transfer film attached to the surface of the counterpart metal during the friction process is not only closely related to the filler modification material but also a key factor affecting the tribological properties of polymer composites; however, there is a lack of feasible methods to quantify the characteristics of the transfer film. In this study, Nano-ZrO2 and polyetheretherketone (PEEK) were filled into a PTFE matrix in order to enhance the wear resistance of polytetrafluoroethylene (PTFE). The tribological properties of the modified PTFE composites were tested using a linear reciprocating friction and wear tester, and the entire friction experiment was designed in seven separate stages. Morphological features were extracted and analyzed from photographs of the transfer film acquired by optical microscopy at each friction stage using an image processing program. The thickness and roughness of the transfer film sections were measured using a non-contact profilometer. Abrasive debris were collected, and their morphological features were observed with an electron microscope. The results showed that the synergistic addition of soft PEEK and hard Nano-ZrO2 particles effectively inhibited interlayer slippage between PTFE molecular chains, dramatically reducing the size and yield of abrasive debris, and facilitated the improvement of the thickness and firmness of the transfer film, which significantly enhanced the wear resistance of the PTFE composites (the lowest volumetric wear rate for Nano-ZrO2/PEEK/PTFE was only 1.76 × 10−4 mm3/Nm). Quantitative analyses of the morphological characteristics of the transfer films revealed that the coverage and roundness of the transfer films gradually increase with the friction stroke, while the aspect ratio and texture entropy subsequently decrease gradually. The coverage, area, mean, third-order moments, and consistency of the transfer film strongly correlated with the volumetric wear rate (correlation coefficient |r| > 0.9). [ABSTRACT FROM AUTHOR]

to investigate and compare the reinforcing effects of glass fibers (GFs) and ZrO 2 nanoparticles at different ratios on the Flexural Strength (FS), Microhardness (MH), and Surface Roughness (SR) of autopolymerizing provisional PMMA. A total of one hundred and twenty specimens of autopolymerizing PMMA were prepared for FS, MH, and SR tests and grouped as follows: no additives (control group), for the tested groups, different ratios of GFs and ZrO 2 at 5% of autopolymerizing PMMA were incorporated. The ratios of GFs/ZrO 2 nanoparticles were 0%-5%, 1%-4%, 2%-3%, 2.5%-2.5%, 3%-2%, 4%-1% and 5%-0% (n = 5). The FS was evaluated using the three-point bending test, MH was evaluated using the Vickers microhardness tester and SR was evaluated using a contact-type profilometer. Data were analyzed using ANOVA, Tukey's test, and Person correlation at 0.05 level of significance. The unreinforced group had the lowest FS, MH, and SR mean values followed by (0%GFs + 5% ZrO 2), (1% GFs + 4% ZrO 2), (2% GFs + 3% ZrO 2), (2.5% GFs + 2.5% ZrO 2), (3% GFs + 2% ZrO 2), (4% GFs + 1% ZrO 2) and (5% GFs + 0% ZrO 2) which had the highest values. Hybrid reinforcement with GFs, ZrO 2 nanoparticles, or a combination of them effectively improved flexural strength and microhardness of autopolymerizing provisional PMMA that would create provisional restorations with extended clinical service. GFs demonstrated superior reinforcing effects compared to ZrO 2 nanoparticles. However, reinforcement with 2.5–5% GFs increased the surface roughness for provisional restoration. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the influence of denture cleansers on the color, stability, and surface roughness of three-dimensional (3D)-printed denture base resins modified with zirconium dioxide nanoparticles (nano-ZrO2). A total of 440 specimens were fabricated using one heat-polymerized resin, and two 3D-printed resins (NextDent and ASIGA). According to the nano-ZrO2 content, the specimens for each resin were divided into five groups (0%, 0.5%wt, 1%wt, 3%wt, and 5%wt). Each concentration was divided into four subgroups (n = 10) based on the immersion solution (distilled water, sodium hypochlorite, Corega, and Fittydent) and immersion duration (360 and 720 days). The color changes (∆E00) and surface roughness (Ra, µm) of each specimen were measured at different time intervals (base line, 360 days, 720 days) using a spectrophotometer and a non-contact profilometer, respectively. The results were statistically analyzed using ANOVA and a post hoc Tukey’s test (α = 0.05). Sodium hypochlorite showed the highest significant color change of all the denture base resins (p < 0.001). The average value of ΔE00 for sodium hypochlorite was significantly higher than the values for the other solutions (Fittydent, Corega, and water) (p < 0.001). Color stability was significantly affected by immersion time for all types of solutions except Corega (p < 0.001). All of the tested immersion solutions (distilled water, sodium hypochlorite, Corega, and Fittydent) showed a significant increase in the surface roughness of all the denture base resins (p < 0.05). Surface roughness was substantially increased by immersion time for all types of solution except Fittydent (p < 0.001). Denture cleansers can result in substantial color change and affect the surface roughness of unmodified and nanoparticle-modified denture base resins. Therefore, the selection of denture cleanser and appropriate types of material is critical for denture longevity.

The main aim of this experiment was to determine the thermal conductivity of two nanofluids, ZrO2/DW and SiC/DW, under different temperatures and concentrations as compared to the base fluid. In this work, zirconium oxide and silicon carbide nanoparticles were obtained, and the nanofluids were prepared using a two-stage method by dispersing the nanoparticles in distilled water (DW) by the ultrasonic processor and a magnetic mixture. Field emission scanning electron microscopy (FESEM), Energy-dispersive x-ray spectrometer (EDX), Transmission Electron Microscope (TEM), and X-ray diffraction (XRD) techniques were used to microstructural and characterize the nanoparticles. Stability of nanofluids were examined by zeta potential test. After that, thermal conductivity was measured using the thermal hot wire method using a KD2-Pro thermal analyzer at temperatures ranging from 20 to 60 °C. Solid volume fractions (φ) of 0.025%, 0.05%, 0.075%, and 0.1% were used. The results showed that the thermal conductivity of the nanofluid was enhanced with increased volume fractions and temperature. The highest recorded thermal conductivity was at the highest temperature 60 °C and solid volume fraction 0.1%. The thermal conductivity enhancement for ZrO2/DW at the volume fraction of 0.1% was 20.455%, and that of SiC/DW was 30.303%. The enhancement was compared to that of the base fluid, distilled water. Finally, based on experimental data, A new mathematical correlations were obtained by curve-fitting. The correlations were used to estimate the thermal conductivity of ZrO2/DW and SiC/DW nanofluids at different solid volume fractions and temperatures. The results obtained were compared to a correlation to determine their accuracy. The deviations from the presented correlations were 1.49% and 1.2% for ZrO2/DW and SiC/DW, respectively. The comparison between experimental results and correlation outputs showed a good agreement which signifies that the results were accurate.

In general, A nanofluid is a substance in which solids and fluids are mixed. The nano-powder of zirconium oxide (ZrO2) and silicon carbide (SiC) was dispersed into the distilled water (DW) using the widely adopted two-step technique. A Brookfield viscometer was used to measure the viscosity of the nanoparticles of ZrO2/DW and SiC/DW, where the temperature ranged between 20 and 60 °C and different solid volume fractions of 0.025, 0.05, 0.075, and 0.1 % were used. An examination of the mono nanofluids of ZrO2/DW and SiC/DW was conducted to assess their rheological behaviour. The findings of the experiments revealed that the Newtonian behaviour did not change when the nano-powder was added. Increasing the solid volume fraction of the nanoparticles and lowering the temperature resulted in the sample's dynamic viscosity being augmented. Hence, as the temperature rose, nanoparticles had a more observable impact on the viscosity. Furthermore, the findings showed that the increase in the ZrO2/DW nanofluid's viscosity peaked at 226.3 %, whereas for the SiC/DW nanofluid, it was 110.5 %. Additionally, according to the results of the experiments, new correlations capable of predicting the investigated nanofluids' viscosity in relation to solid concentration and temperature has been suggested. The study's results could motivate expanded utilization of nanofluids by researchers working on energy applications.

A high-level research is currently focused on the construction of polymer nanocomposite membranes with high proton conductivity (PC), peak power density (PD), and open circuit voltage (OCV) for polymer electrolyte membrane fuel cells (PEMFC) to substitute the commercial Nafion-211 membrane. The present study deals with the solvent-casting process for producing ZrO 2 nanoparticles (1–7 wt %) dispersed on phosphoric acid (PA) doped polyethylene imine and polyvinyl alcohol (PA-PEI/PVA) polymer nanocomposites (PNCs). ZrO 2 (5%) dispersed PA-PVA/PEI PNCs showed the highest ion-exchange capacity (IEC) of 2.94 mmol/g−1 at room temperature (RT), and PC of 4.34 10−2 S/cm−1 at 120 °C. Experiments on the PNCs were carried out at 120 °C to evaluate their performance and usability in medium-temperature polymer electrolyte membrane fuel cells (MT-PEMFCs). The results indicate a practical and effective route for the fabrication of a composite membrane that has a semi-interpenetration network structure with abundant active protonated groups, and has future prospects and widespread application in MT-PEMFCs. • ZrO 2 /PA-PEI/PVA polymer nanocomposites are innovative, inexpensive, and easy to create. • They have high ion-exchange capacity (2.94 mmol/g−1) and proton conductivity (4.34 10−2 S/cm−1). • The composites are exhibit ideal characteristics for polymer electrolyte fuel cells. • The composite has future prospects and widespread application in MT-PEMFCs. [ABSTRACT FROM AUTHOR]

To improve the wear resistance of the surface of the cotton picker spindle, a Ni-Co-ZrO2 composite coating with different ZrO2 nanoparticle concentrations was prepared using electrodeposition technology on the micro surface of spindle hook teeth, and the morphologies of the surface and cross-section, element contents, grain sizes, microhardness and friction coefficients of the Ni-Co-ZrO2 composite coating were obtained; a simulated wear test was conducted based on the independently developed spindle hook tooth wear device, and the morphologies and elemental distributions of the composite coating before and after wear were obtained; the effects of different ZrO2 nanoparticle concentrations (0, 2, 4, 6, 8 g/L) on the morphology, element content, grain size, microhardness, friction coefficient and wear resistance of the coating were discussed. The test results indicated that compared with Ni-Co coatings, Ni-Co-ZrO2 composite coatings featured a more compact coating structure, a greater coating thickness, and a smaller grain size. The presence of ZrO2 nanoparticles led to further improvement of the coating's microhardness, friction coefficient and wear resistance. When the mass concentration of ZrO2 nanoparticles reached 4 g/L, the microhardness of Ni-Co-ZrO2 composite coating reached the maximum value, 545.4 Hv0.1, and the friction coefficient decreased to 0.06. At the same time, in the simulated wear test, the composite coating with this concentration had the smallest wear area and the highest wear resistance. [ABSTRACT FROM AUTHOR]

A stable superhydrophobic FAS-ZrO 2 (FZr-ESS) surface was created by chemically etching and modifying a 304 stainless steel substrate. The effect of etching parameters such as time and temperature on the surface wetting properties was studied and optimized. The etched steel surface exhibited a honeycomb-like microstructure that, coupled with the low surface energy of the fluorinated ZrO 2 nanoparticles, produced a FZr-ESS surface with a surface contact angle (CA) of 165.9° and a sliding angle (SA) of 1.7°. The presence of highly stable functionalized ZrO 2 conjugated to the steel matrix contributed to the surface's outstanding mechanical stability, as confirmed by tape peeling and sandpaper abrasion tests. Furthermore, the FZr-ESS surface demonstrated exceptional chemical stability under a variety of pH conditions due to its excellent water repellency. An electrochemical test showed that the resulting surface was highly resistant to corrosion, with the corrosion current density reduced by nearly two orders of magnitude compared to bare stainless steel. The superhydrophobic FZr-ESS surface also displayed excellent long-term stability, wetting diversity, and self-cleaning behavior, making it highly versatile for a range of applications. [ABSTRACT FROM AUTHOR]

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This research aimed to find the suitable condition for the fabrication of AlZnMgCu1.5-T6/ZrO2 nanocomposites to improve the mechanical properties and wear resistance of the produced surface nanocomposites. The effects of rotational speed and the number of passes were investigated to obtain the desired properties. For this purpose, rotational speeds of 1000 rpm, 1200 rpm, and 1400 rpm were used along with a constant traverse speed of 40 mm/min, and the number of processing passes was considered to be one and two passes. Optical microscopy and electron microscopy equipped with an EDS system were used to study the microstructural evolution, such as grain refinement and distribution of nanoparticles in these nanocomposites. To evaluate the mechanical and wear properties of the nanocomposites, tension, hardness, and wear tests were performed according to related standards. In the next step, the fracture surfaces were examined by XRD to investigate the formation of possible phases. Finally, fracture and wear surfaces were investigated to determine dominant mechanisms. In addition to the absence of defects, an extreme grain refinement due to the severe plastic deformation of the grains and the presence of ceramic nanoparticles were confirmed by microscopic observations. According to the results, due to the extreme grain refinement and the presence of ZrO2 hard ceramic nanoparticles, the average and maximum hardness values increased up to 33% and 48%, respectively, compared to those of the aluminum alloy matrix. Also, the wear rate was reduced up to 65%. It was concluded that according to the findings, the most suitable condition for achieving the optimal mechanical and wear properties is 1400 rpm-two passes.

Polytetrafluoroethylene (PTFE) is a polymeric material with excellent self-lubricating properties. In this study, in order to improve the wear resistance of PTFE, the PTFE matrix was filled with soft-phase polyetheretherketone (PEEK) particles and hard-phase nano-ZrO2 particles in varying volume ratios. A linear reciprocating friction tester was used to test the tribological properties of the PTFE composites. Optical microscopy (OM) and scanning electron microscopy (SEM) were utilized to observe the formation and evolution of the transfer film on the surface of the counterpart metal during the friction process. Molecular dynamics simulation software (Materials Studio MS) was used to simulate and analyze the frictional behavior between the molecular structures of PTFE composites and the counterpart iron atoms on a microscopic scale. The results showed that the uniformity and firmness of the transfer film had an important influence on the wear resistance of the material. PEEK and ZrO2 nanoparticles were able to improve the firmness and formation rate of the transfer film, respectively, resulting in significant improvement in the wear resistance of PTFE (volume wear rate reduced from 7.7 × 10−4 mm3/Nm for pure PTFE to 1.76 × 10−6 mm3/Nm for nano-ZrO2/PEEK/PTFE). Molecular dynamics simulations revealed that the poor wear resistance of PTFE was due to significant interlayer slippage within its molecular chains. PEEK molecular chains could effectively adsorb PTFE molecular chains and formed a strong bond. ZrO2 nanoparticles also contributed to the overall stability of the PTFE matrix. Both soft and hard fillers significantly inhibited interlayer slippage between PTFE molecular chains, enhancing the shear deformation resistance of the material and thus improving the wear resistance of PTFE composites. [ABSTRACT FROM AUTHOR]

Poly(methyl methacrylate) (PMMA) is a commonly used material, as it is biocompatible and relatively cheap. However, its mechanical properties and weak antibiofilm activity are major concerns. With the development of new technology, 3D-printed resins are emerging as replacements for PMMA. Few studies have investigated the antibiofilm activity of 3D-printed resins. Therefore, this study aimed to investigate the antibiofilm activity and surface roughness of a 3D-printed denture base resin modified with different concentrations of zirconium dioxide nanoparticles (ZrO2 NPs). A total of 60 resin disc specimens (15 × 2 mm) were fabricated and divided into six groups (n = 10). The groups comprised a heat-polymerized resin (PMMA) group, an unmodified 3D-printed resin (NextDent) group, and four 3D-printed resin groups that were modified with ZrO2 NPs at various concentrations (0.5 wt%, 1 wt%, 3 wt%, and 5 wt%). All specimens were polished using a conventional method and then placed in a thermocycler machine for 5000 cycles. Surface roughness (Ra, µm) was measured using a non-contact profilometer. The adhesion of Candida albicans (C. albicans) was measured using a fungal adhesion assay that consisted of a colony forming unit assay and a cell proliferation assay. The data were analyzed using Shapiro–Wilk and Kruskal–Wallis tests. A Mann–Whitney U test was used for pairwise comparison, and p-values of less than 0.05 were considered statistically significant. The lowest Ra value (0.88 ± 0.087 µm) was recorded for the PMMA group. In comparison to the PMMA group, the 3% ZrO2 NPs 3D-printed group showed a significant increase in Ra (p < 0.025). For the 3D-printed resins, significant differences were found between the groups with 0% vs. 3% ZrO2 NPs and 3% vs. 5% ZrO2 NPs (p < 0.025). The highest Ra value (0.96 ± 0.06 µm) was recorded for the 3% ZrO2 NPs group, and the lowest Ra values (0.91 ± 0.03 µm) were recorded for the 0.5% and 5% ZrO2 NPs groups. In terms of antifungal activity, the cell proliferation assay showed a significant decrease in the C. albicans count for the 0.5% ZrO2 NPs group when compared with PMMA and all other groups of 3D-printed resins. The group with the lowest concentration of ZrO2 NPs (0.5%) showed the lowest level of C. albicans adhesion of all the tested groups and showed the lowest Candida count (0.29 ± 0.03). The addition of ZrO2 NPs in low concentrations did not affect the surface roughness of the 3D-printed resins. These 3D-printed resins with low concentrations of nanocomposites could be used as possible materials for the prevention and treatment of denture stomatitis, due to their antibiofilm activities. [ABSTRACT FROM AUTHOR]

The green biogenic synthesis of nanoparticles using natural sources is always eco-friendly and attractive. The current study has focused on the production of ZrO2 nanoparticles using the aqueous leaf extract of Laurus nobilis (bay leaf). The structural and morphological properties of ZrO2 nanoparticles were investigated through UV–visible absorption spectrophotometer, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and dynamic light scattering (DLS). The characterization techniques confirmed the formation of ZrO2 nanoparticles with the diameter from 20 to 100 nm. FTIR spectra also demonstrated the formation of ZrO2 in the crystalline phase. The narrow and edged peaks obtained from XRD symbolized a notable increase in the crystalline index of the obtained zirconium nanoparticles. The SEM micrographs revealed the morphology as spherical shaped. Various concentrations of the obtained zirconium nanoparticles were tested to check their inhibitory action against certain microorganisms such as Gram-positive bacteria, Gram-negative bacteria and a fungus. The inhibitory actions against the tested microorganisms were directly proportional to the concentration of the obtained zirconium nanoparticles. Consequently, the dispersion properties of ZrO2 nanoparticles in the aqueous solution increased considerably, which might have contributed to the antimicrobial activity. Hence, the synthesized ZrO2 nanoparticles of L. nobilis can serve as an antimicrobial agent, which may play a vital role in medical industry. [ABSTRACT FROM AUTHOR]

This study investigated the translucency of 3D-printed denture base resins modified with zirconium dioxide nanoparticles (ZrO2NPs) under thermal cycling. A total of 110 specimens were fabricated and divided into 3 groups according to the materials, i.e., heat-polymerized resin, and 3D-printed resins (NextDent, and ASIGA). The 3D-printed resins were modified with 0, 0.5, 1, 3, and 5 wt.% of ZrO2NPs. All the specimens were subjected to 5000 thermal cycles. The translucency was measured using a spectrophotometer. The results showed that the heat-polymerized resin had considerably higher translucency than the 3D-printed resins. Compared to the unmodified group, the translucency decreased significantly after adding 5% ZrO2NPs to NextDent and 3% ZrO2NPs to ASIGA resins. The highest translucency was achieved for NextDent by adding 0.5% ZrO2NPs and for ASIGA without any ZrO2NPs. It was found that the average concentration level in ASIGA was significantly higher than that in NextDent. These findings revealed that 3D-printed resins have lower translucency than heat-polymerized acrylic resin, and adding ZrO2NPs at low concentrations did not affect the translucency of the 3D-printed resins. Therefore, in terms of translucency, 3D-printed nanocomposite denture base resins could be considered for clinical applications when ZrO2NPs are added at low concentrations. [ABSTRACT FROM AUTHOR]

In this work, crosslinked chitosan-citrate/ZrO 2 (CS-CIT/ZrO 2) nanocomposite was straightforwardly synthesized in two steps: first, chitosan biopolymer (CS) was functionalized with a zirconia inorganic nanomaterial (zirconium dioxide, ZrO 2), and then, citrate (CIT) was used in an ionic cross-linking procedure. This new nanocomposite's physicochemical characteristics have been fully investigated using methods including FTIR, CHN–O, BET, pH pzc , XRD, and FESEM-EDX. Using the response surface methodology approach, the removal of cationic dye (Safranin O, SO) from an aqueous solution by CS-CIT/ZrO 2 was thoroughly investigated with concerning adsorption factors (pH (4–10), duration (10–90 min), and CS-CIT/ZrO 2 dosage (0.02–0.08 g)). Freundlich isotherm demonstrates the equilibrium behavior of SO by CS-CIT/ZrO 2. The optimal conditions for achieving the maximum removal of SO (70.7 %) were found to be at pH 10.0, with a dosage of CS-CIT/ZrO 2 of 0.05 g/L, and a time of 90 min, depending on the desirability function. A pseudo-first-order model characterized the kinetics data of SO adsorption by CS-CIT/ZrO 2 in an adequate manner. CS-CIT/ZrO 2 has a remarkable adsorption capacity of 280.14 mg/g. The effective adsorption of SO on the positively charged CS-CIT/ZrO 2 is responsible for the electrostatic interactions between the SO cation and the negatively charged CS-CIT/ZrO 2 , along with the H-bond and n-π interactions. According to this work, CS-CIT/ZrO 2 has great promise as a superior bioadsorbent for adsorption of synthesized cationic dyes from polluted water. [Display omitted] • Functionalization of chitosan polymer by citrate and ZrO 2 nanoparticles was attained. • The functionalized chitosan (CS-CIT/ZrO 2) was applied to remove Safranin O dye. • The response surface methodology approach was applied to optimize the adsorption process. • A pseudo-first-order model characterized the kinetics data of SO adsorption. • CS-CIT/ZrO 2 has a remarkable adsorption capacity of 280.14 mg/g. [ABSTRACT FROM AUTHOR]

The materials tribology community has identified that the transfer film attached to the surface of the counterpart metal during the friction process is not only closely related to the filler modification material but also a key factor affecting the tribological properties of polymer composites; however, there is a lack of feasible methods to quantify the characteristics of the transfer film. In this study, Nano-ZrO2 and polyetheretherketone (PEEK) were filled into a PTFE matrix in order to enhance the wear resistance of polytetrafluoroethylene (PTFE). The tribological properties of the modified PTFE composites were tested using a linear reciprocating friction and wear tester, and the entire friction experiment was designed in seven separate stages. Morphological features were extracted and analyzed from photographs of the transfer film acquired by optical microscopy at each friction stage using an image processing program. The thickness and roughness of the transfer film sections were measured using a non-contact profilometer. Abrasive debris were collected, and their morphological features were observed with an electron microscope. The results showed that the synergistic addition of soft PEEK and hard Nano-ZrO2 particles effectively inhibited interlayer slippage between PTFE molecular chains, dramatically reducing the size and yield of abrasive debris, and facilitated the improvement of the thickness and firmness of the transfer film, which significantly enhanced the wear resistance of the PTFE composites (the lowest volumetric wear rate for Nano-ZrO2/PEEK/PTFE was only 1.76 × 10−4 mm3/Nm). Quantitative analyses of the morphological characteristics of the transfer films revealed that the coverage and roundness of the transfer films gradually increase with the friction stroke, while the aspect ratio and texture entropy subsequently decrease gradually. The coverage, area, mean, third-order moments, and consistency of the transfer film strongly correlated with the volumetric wear rate (correlation coefficient |r| > 0.9).

The progress in tribocorrosion performance of the engineering parts is in dire need of improving their surface properties. In the present contribution, Ni-Cr-ZrO 2 layers were electrodeposited on St37 steel. The stress was put on optimizing the process factors, including the parameters involved in pulsed current electrodeposition and level of the ZrO 2 reinforcing nanoparticles (0-20 g/L) in the bath. The surface characteristics of the electrodeposits were evaluated using FESEM, EDS, AFM, and XRD. The tribomechanical characteristics of the films were determined using a Vickers microhardness tester and pin-on-disk apparatus. The electrochemical behavior of the samples was studied using OCP, EIS, PDP, and immersion techniques. The results demonstrated that the included ZrO 2 nanoparticles led to more homogenous, rougher, and defect-free surfaces, while they did not change the phase composition of the alloy electrodeposits. The polarization resistance of the Ni-Cr alloy coating increases by 6.7 times when 10 g/L of the reinforcing nanoparticles is added to the electrolyte. A decrease of ≈42 % in the mean COF value was obtained by the incorporation of 10 g/L ZrO 2 nanoparticles into the plating bath. The coating system developed holds the promise to address both technical requirements and health concerns., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (© 2024 The Authors.)

To improve the wear resistance of the surface of the cotton picker spindle, a Ni-Co-ZrO2 composite coating with different ZrO2 nanoparticle concentrations was prepared using electrodeposition technology on the micro surface of spindle hook teeth, and the morphologies of the surface and cross-section, element contents, grain sizes, microhardness and friction coefficients of the Ni-Co-ZrO2 composite coating were obtained; a simulated wear test was conducted based on the independently developed spindle hook tooth wear device, and the morphologies and elemental distributions of the composite coating before and after wear were obtained; the effects of different ZrO2 nanoparticle concentrations (0, 2, 4, 6, 8 g/L) on the morphology, element content, grain size, microhardness, friction coefficient and wear resistance of the coating were discussed. The test results indicated that compared with Ni-Co coatings, Ni-Co-ZrO2 composite coatings featured a more compact coating structure, a greater coating thickness, and a smaller grain size. The presence of ZrO2 nanoparticles led to further improvement of the coating’s microhardness, friction coefficient and wear resistance. When the mass concentration of ZrO2 nanoparticles reached 4 g/L, the microhardness of Ni-Co-ZrO2 composite coating reached the maximum value, 545.4 Hv0.1, and the friction coefficient decreased to 0.06. At the same time, in the simulated wear test, the composite coating with this concentration had the smallest wear area and the highest wear resistance.

The aim of this study was to investigate the potential antimicrobial and cytotoxic effect of modified 3D printed resin with ZrO 2 nanoparticles, as long-term provisional restoration. In addition, the study involved artificial aging process for three months to observe stability of 3D printed resin. Functionalized ZrO 2 nanoparticles with γ-MPS were characterized using transmission electron microscopy, scanning electron microscope and Fourier-transform infrared spectroscopy. Dental resin was incrementally impregnated with γ-MPS modified nanoparticles at different concentrations (0, 1, 3, and 5 wt%). Specimens were printed, post-cured and placed in artificial saliva at 37 oC for 48 h or aged for 3 months. Discrepancy in composition and roughness were monitored using FTIR and AFM, respectively. Biocompatibility was evaluated using human oral fibroblasts. Antimicrobials capacity and biofilm adhesion were measured with Streptococcus mutans and Candida albicans. The microscopic and spectroscopic analyses confirmed γ-MPS coating around ZrO 2 nanoparticles. The addition of nanoparticles (>1 wt%) significantly increased the surface roughness. Cytotoxicity results were in agreement with the recommended range of oral biomaterials standard. Moreover, the antimicrobial activity significantly improved with increasing the filler concentration. Despite the decrease in antimicrobial efficacy after 3 months of aging, modified resin revealed a critical ability to dominate biofilm formation. The addition of ZrO 2 nanoparticles showed significant antimicrobial capability of a 3D printed resin without inducing any cellular side effects. Thus, the modification of a 3D printed resin with ZrO 2 nanoparticles has a promising future in the dental field for fabricating long-term provisional restorations. [Display omitted] • ZrO 2 nanoparticles were functionalized and modified 3D printed resin material. • ZrO 2 nanoparticles had physical interaction and homogenized distribution with resin. • Higher concentrations significantly altered surface morphology and roughness. • Direct and indirect cytotoxicity assay found modified resin to be biocompatible. • Incorporation of ZrO 2 significantly reduced biofilm formation and adhesion. [ABSTRACT FROM AUTHOR]

Due to the low mechanical performances of 3D-printed denture base resins, ZrO2 nanoparticles (ZrO2NPs) were incorporated into different 3D-printed resins and their effects on the flexure strength, elastic modulus, impact strength, hardness, and surface roughness were evaluated. A total of 286 specimens were fabricated in dimensions per respective test and divided according to materials into three groups: heat-polymerized as a control group and two 3D-printed resins (NextDent and ASIGA) which were modified with 0.5 wt.%, 1 wt.%, 3 wt.%, and 5 wt.% ZrO2NPs. The flexure strength and elastic modulus, impact strength, hardness, and surface roughness (µm) were measured using the three-point bending test, Charpy's impact test, Vickers hardness test, and a profilometer, respectively. The data were analyzed by ANOVA and Tukey's post hoc test (α = 0.05). The results showed that, in comparison to heat-polymerized resin, the unmodified 3D-printed resins showed a significant decrease in all tested properties (p < 0.001) except surface roughness (p = 0.11). In between 3D-printed resins, the addition of ZrO2NPs to 3D-printed resins showed a significant increase in flexure strength, impact strength, and hardness (p < 0.05) while showing no significant differences in surface roughness and elastic modulus (p > 0.05). Our study demonstrated that the unmodified 3D-printed resins showed inferior mechanical behavior when compared with heat-polymerized acrylic resin while the addition of ZrO2NPs improved the properties of 3D-printed resins. Therefore, the introduced 3D-printable nanocomposite denture-base resins are suitable for clinical use. [ABSTRACT FROM AUTHOR]

The (PMMA–ZrO2–Ag) nanocomposites are fabricated by using casting method. Nano-zirconia and nano-silver are added to polymethyl methacrylate at different weight percent (0%, 0.75%, 1.5%, and 2.25%); nanozirconia and nano-silver are attached to PMMA at equal weight percent. The effect of the ZrO2 and Ag nanoparticles as promoters on the structural and mechanical properties of PMMA is characterized by optical microscopy, hardness and compression tests. The hardness of polymethyl methacrylate is increased with the increase in the ZrO2 and Ag nanoparticles’ concentration, but then is decreased after 2.25 weight percent. The compression strength of PMMA is gained with increasing nano-zirconia and nano-silver contents. The present work shows that the prepared samples can be used for dental applications. [ABSTRACT FROM AUTHOR]

ZrO2 nanoparticles (ZNPs) have excellent physical properties. This study investigated the fracture load of implant-supported, fixed cantilevered prosthesis materials, reinforced with ZNPs and various polymerization techniques, compared with conventional and CAD/CAM materials. Sixty specimens were made from two CAD/CAM; milled (MIL) (Ceramill TEMP); and 3D-printed (NextDent Denture 3D+). Conventional heat-polymerized acrylic resin was used to fabricate the other specimens, which were grouped according to their polymerization technique: conventionally (HP) and autoclave-polymerized (AP); conventionally cured and reinforced with 5 wt% ZNPs (HPZNP); and autoclave reinforced with 5 wt% ZNPs (APZNP). The specimens were thermocycled (5000 cycles/30 s dwell time). Each specimen was subjected to static vertical loading (1 mm/min) using a universal Instron testing machine until fracture. Scanning electron microscopy was used for fracture surface analyses. The ANOVA showed significant fracture load differences between all the tested groups (p = 0.001). The Tukey post hoc tests indicated a significant difference in fracture load between all tested groups (p ˂ 0.001) except HP vs. HPZNP and AP vs. MIL. APZNP had the lowest mean fracture load value (380.7 ± 52.8 N), while MIL had the highest (926.6 ± 82.8 N). The CAD/CAM materials exhibited the highest fracture load values, indicating that they could be used in long-term interim prostheses. Autoclave polymerization improved fracture load performance, whereas ZrO2 nanoparticles decreased the fracture load performance of cantilevered prostheses. [ABSTRACT FROM AUTHOR]

[Display omitted] • ZrO 2 nanoparticles were successfully embedded in ZIF-8-derived N -doped porous carbon. • Charge storage is mainly realized by the diffusion-controlled process. • Phosphorus uptake capacity can be enhanced by adding Zr into N -doped porous carbon. • Ligand exchange and electrostatic attraction contribute to phosphorus removal. Excessive phosphorus discharges are not favorable to the normal functioning of water ecosystems. Although some treatments have been implemented to control phosphorus concentrations in sewage, several challenges remain for them. Capacitive deionization technology (CDI) possesses excellent potential for phosphorus removal, and the electrode material is the key to CDI. Herein, a novel ZIF-8-derived N -doped porous carbon electrode enabled with in situ embedded ZrO 2 nanoparticles (ZNPC) was fabricated through a simple in-situ growth approach. The experimental results demonstrate that ZrO 2 embedded in ZNPC can improve the electrochemical performance and provide suitable affinity sites for phosphorus, thus enhancing the electrode performance in capturing phosphorus. Isothermal and kinetic models were adopted to investigate the phosphorus uptake process. Mechanism analysis reveals that the phosphorus removal behavior is associated with the electric field, ligand exchange, and electrostatic attraction. This study provides a promising approach for facile constructing Zr-based N -doped porous carbon and expands its potential utility for phosphorus removal from aqueous solutions. [ABSTRACT FROM AUTHOR]

Polytetrafluoroethylene (PTFE) is a polymeric material with excellent self-lubricating properties. In this study, in order to improve the wear resistance of PTFE, the PTFE matrix was filled with soft-phase polyetheretherketone (PEEK) particles and hard-phase nano-ZrO2 particles in varying volume ratios. A linear reciprocating friction tester was used to test the tribological properties of the PTFE composites. Optical microscopy (OM) and scanning electron microscopy (SEM) were utilized to observe the formation and evolution of the transfer film on the surface of the counterpart metal during the friction process. Molecular dynamics simulation software (Materials Studio MS) was used to simulate and analyze the frictional behavior between the molecular structures of PTFE composites and the counterpart iron atoms on a microscopic scale. The results showed that the uniformity and firmness of the transfer film had an important influence on the wear resistance of the material. PEEK and ZrO2 nanoparticles were able to improve the firmness and formation rate of the transfer film, respectively, resulting in significant improvement in the wear resistance of PTFE (volume wear rate reduced from 7.7 × 10−4 mm3/Nm for pure PTFE to 1.76 × 10−6 mm3/Nm for nano-ZrO2/PEEK/PTFE). Molecular dynamics simulations revealed that the poor wear resistance of PTFE was due to significant interlayer slippage within its molecular chains. PEEK molecular chains could effectively adsorb PTFE molecular chains and formed a strong bond. ZrO2 nanoparticles also contributed to the overall stability of the PTFE matrix. Both soft and hard fillers significantly inhibited interlayer slippage between PTFE molecular chains, enhancing the shear deformation resistance of the material and thus improving the wear resistance of PTFE composites.

Pollution and diseases such as the coronavirus pandemic (COVID-19) are major issues that may be solved partly by nanotechnology. Here we review the synthesis of ZrO2 nanoparticles and their nanocomposites using compounds from bacteria, fungi, microalgae, and plants. For instance, bacteria, microalgae, and fungi secret bioactive metabolites such as fucoidans, digestive enzymes, and proteins, while plant tissues are rich in reducing sugars, polyphenols, flavonoids, saponins, and amino acids. These compounds allow reducing, capping, chelating, and stabilizing during the transformation of Zr4+ into ZrO2 nanoparticles. Green ZrO2 nanoparticles display unique properties such as a nanoscale size of 5–50 nm, diverse morphologies, e.g. nanospheres, nanorods and nanochains, and wide bandgap energy of 3.7–5.5 eV. Their high stability and biocompatibility are suitable biomedical and environmental applications, such as pathogen and cancer inactivation, and pollutant removal. Emerging applications of green ZrO2-based nanocomposites include water treatment, catalytic reduction, nanoelectronic devices, and anti-biofilms. [ABSTRACT FROM AUTHOR]

Tetragonal zirconia (t‐ZrO2) nanoparticles (NPs) were successfully synthesized by a green method using β‐cyclodextrin as stabilizer. The structural characterization of the prepared nanoparticles was done by X‐ray diffraction (XRD).The tetragonal crystalline structure of ZrO2 NPs was confirmed by XRD analysis. We employed the Rietveld method to refine the XRD data and the refinement result leads to specify the tetragonal phase of ZrO2 NPs with space group P 42/n m c. The FTIR spectrum gives the information about the presence of Zr−O bonding at 501 cm−1. Particle size and morphological properties were demonstrated by Scanning Electron Microscope (SEM) and elemental compositions were analysed using EDAX spectrum. The band gap energy was estimated using optical absorption spectroscopy and the value was found to be 3.99 eV. The UV (310 nm) and visible (401, 420 and 560 nm) emissions were observed from PL spectrum. Brunauer‐Emmet‐Teller (BET) surface analysis was used for determining the surface area and average pore size of ZrO2 NPs.The photocatalytic degradation of the prepared ZrO2 NPs for organic dyes had been studied under visible light irradiation. Results showed that 68 % degradation was achieved within 135 min for Methylene Blue (MB) dye but other dyes almost remains unchanged during the same reaction times. [ABSTRACT FROM AUTHOR]

The authors' previous study showed that zirconium oxide nanoparticles (ZrO2 NPs) induce toxic effects in MC3T3‐E1 cells; however, its toxicological mechanism is still unclear. Liquid chromatography–mass spectrometry/time‐of‐flight mass spectrometry was used to reveal the metabolite profile and toxicological mechanism of MC3T3‐E1 cells in response to ZrO2 NPs. The results demonstrated that MC3T3‐E1 cells treated with ZrO2 NPs for 24 and 48 h presented different metabolic characteristics. Following ZrO2 NP treatment for 24 h, 96 upregulated and 129 downregulated metabolites in the positive ion mode, as well as 91 upregulated and 326 downregulated metabolites in the negative ion mode were identified. Following ZrO2 NP treatment for 48 h, 33 upregulated and 174 downregulated metabolites were identified in the positive ion mode, whereas 37 upregulated and 302 downregulated metabolites were confirmed in the negative ion mode. Among them, 42 differential metabolites were recognised as potential metabolites contributing to the induced toxic effects of ZrO2 NPs in MC3T3‐E1 cells. Most of the differential metabolites were lysophosphatidylcholine and lysophosphatidylethanolamide, indicating that exposure to ZrO2 NPs may have a profound impact on human cellular function by impairing the membrane system. The results also provide new clues for the toxicological mechanism of ZrO2 NP dental materials. [ABSTRACT FROM AUTHOR]

This work aims preparation of Ni-based nanocomposite coating by electroless deposition method onto stainless steel (316L) substrate, the present work will compare the effects of incorporation of ZrO2 nanoparticles at different percentages (1.25 wt %, 2.25 wt %, and 4.25 wt %) Ni-based electroless deposition coating of the bath nanocomposite on the phase structure, microhardness, and corrosion resistance is studied. Where the structure and chemical composition of nanocomposite coatings were studied by using (X-ray), (SEM) and (EDS). of Ni - ZrO2 nanocomposite coating exhibits much-increased microhardness and remarkably improved corrosion resistance

Poly(methyl methacrylate) (PMMA) is a commonly used material, as it is biocompatible and relatively cheap. However, its mechanical properties and weak antibiofilm activity are major concerns. With the development of new technology, 3D-printed resins are emerging as replacements for PMMA. Few studies have investigated the antibiofilm activity of 3D-printed resins. Therefore, this study aimed to investigate the antibiofilm activity and surface roughness of a 3D-printed denture base resin modified with different concentrations of zirconium dioxide nanoparticles (ZrO2 NPs). A total of 60 resin disc specimens (15 × 2 mm) were fabricated and divided into six groups (n = 10). The groups comprised a heat-polymerized resin (PMMA) group, an unmodified 3D-printed resin (NextDent) group, and four 3D-printed resin groups that were modified with ZrO2 NPs at various concentrations (0.5 wt%, 1 wt%, 3 wt%, and 5 wt%). All specimens were polished using a conventional method and then placed in a thermocycler machine for 5000 cycles. Surface roughness (Ra, µm) was measured using a non-contact profilometer. The adhesion of Candida albicans (C. albicans) was measured using a fungal adhesion assay that consisted of a colony forming unit assay and a cell proliferation assay. The data were analyzed using Shapiro–Wilk and Kruskal–Wallis tests. A Mann–Whitney U test was used for pairwise comparison, and p-values of less than 0.05 were considered statistically significant. The lowest Ra value (0.88 ± 0.087 µm) was recorded for the PMMA group. In comparison to the PMMA group, the 3% ZrO2 NPs 3D-printed group showed a significant increase in Ra (p < 0.025). For the 3D-printed resins, significant differences were found between the groups with 0% vs. 3% ZrO2 NPs and 3% vs. 5% ZrO2 NPs (p < 0.025). The highest Ra value (0.96 ± 0.06 µm) was recorded for the 3% ZrO2 NPs group, and the lowest Ra values (0.91 ± 0.03 µm) were recorded for the 0.5% and 5% ZrO2 NPs groups. In terms of antifungal activity, the cell proliferation assay showed a significant decrease in the C. albicans count for the 0.5% ZrO2 NPs group when compared with PMMA and all other groups of 3D-printed resins. The group with the lowest concentration of ZrO2 NPs (0.5%) showed the lowest level of C. albicans adhesion of all the tested groups and showed the lowest Candida count (0.29 ± 0.03). The addition of ZrO2 NPs in low concentrations did not affect the surface roughness of the 3D-printed resins. These 3D-printed resins with low concentrations of nanocomposites could be used as possible materials for the prevention and treatment of denture stomatitis, due to their antibiofilm activities.

Nanoparticles of ZrO 2 :Pr stabilized with ytterbium in the range 0.5%mol.-20%mol. were synthesized. Crystallite sizes depended on Yb concentration. Red luminescence resulting from 1D 2 →3H 4 transition of Pr3+ is present in all the samples. Additionally in the samples calcined at 1200 °C blue-green luminescence from 3P 0 level of Pr3+ was found. This emission was more intense than red one. Intensity of the 3P 0 →3H 4 luminescence depended on ytterbium content and was found to be the highest at 20% mol. Yb. Luminescence study had shown, that ytterbium introduced additional lattice defects. Some quantity of praseodymium activator ions were found to be present at +4 state and changed its valence to +3 as ytterbium content had risen. [ABSTRACT FROM AUTHOR]

Polymethyl methacrylate (PMMA) is one of the common widely accepted biomaterials in prosthetic dentistry due to its acceptable advantages, since 1937. In the present work, PMMA reinforced with Al2O3 nanowires (Al2O3 NWs) and ZrO2 nanoparticles (ZrO2 NPs) were fabricated by a self-curing method. Mechanical and tribological tests were conducted to study the effect of nanofillers on the mechanical and tribological performance of PMMA nanocomposites. Compression and microhardness tests, as mechanical tests, were accomplished to estimate the elastic modulus and microhardness number of the present nanocomposites. Also, tribological properties of unfilled PMMA and its nanocomposites were realized by pin-on-disk tester under dry sliding conditions. Wear test was conducted at room temperature under applied loads of 10, 20, 30, 40, and 50 N at a constant sliding speed and distance of 1.256 m/s and 226 m, respectively to study wear rate and coefficient of friction (COF) of the nanocomposites. Experimental results revealed that the elastic modulus, microhardness, wear rate, and COF were enhanced with increasing nanofiller content up to 0.5 and 0.7 wt. % of Al2O3 NWs and ZrO2 NPs, respectively. Also, wear rate increased with increasing applied loads up to 50 N, while COF decreased with increasing applied loads up to 40 N. Finally, specimens' worn surfaces were examined and imaged using scanning electron microscope (SEM). [ABSTRACT FROM AUTHOR]

This study investigated the translucency of 3D-printed denture base resins modified with zirconium dioxide nanoparticles (ZrO2NPs) under thermal cycling. A total of 110 specimens were fabricated and divided into 3 groups according to the materials, i.e., heat-polymerized resin, and 3D-printed resins (NextDent, and ASIGA). The 3D-printed resins were modified with 0, 0.5, 1, 3, and 5 wt.% of ZrO2NPs. All the specimens were subjected to 5000 thermal cycles. The translucency was measured using a spectrophotometer. The results showed that the heat-polymerized resin had considerably higher translucency than the 3D-printed resins. Compared to the unmodified group, the translucency decreased significantly after adding 5% ZrO2NPs to NextDent and 3% ZrO2NPs to ASIGA resins. The highest translucency was achieved for NextDent by adding 0.5% ZrO2NPs and for ASIGA without any ZrO2NPs. It was found that the average concentration level in ASIGA was significantly higher than that in NextDent. These findings revealed that 3D-printed resins have lower translucency than heat-polymerized acrylic resin, and adding ZrO2NPs at low concentrations did not affect the translucency of the 3D-printed resins. Therefore, in terms of translucency, 3D-printed nanocomposite denture base resins could be considered for clinical applications when ZrO2NPs are added at low concentrations.

Background: Polymerization shrinkage and fracture are the two common trouble shoots with denture base resins. Polymerization shrinkage affects the dimensional accuracy and fit of the prosthesis. The effect of zirconia (ZrO2) nanoparticles on polymerization shrinkage is not documented yet. Purpose: The aim and objective of this study were to evaluate the impact strength and dimensional accuracy of heat-cured poly methyl methacrylate (PMMA) on reinforcement with ZrO2 nanoparticles. Materials and Methods: Conventional heat-cure denture base resin (control) and the polymer reinforced with 3, 5, and 7 wt% of ZrO2 nanoparticles were prepared and used in this study. Forty bar-shaped specimens were prepared and tested for impact strength using Charpy’s type impact tester. Forty denture bases were fabricated and checked for dimensional accuracy by measuring the distance between the denture base and the cast in two different sections using the travelling microscope. Results: The impact strength decreased with increased concentration of ZrO2 and found to be least at 7 wt% concentration (2.01±0.26 J/mm2). The distance between the denture base and the cast significantly decreased both in the posterior palatal seal region (0.060±0.007cm) and mid-palatine section region (0.057±0.006cm) with ZrO2 nanoparticles reinforcement and was found to be least at 7 wt% concentration. Conclusion: Reinforcement of heat-cured PMMA with ZrO2 nanoparticles significantly increased the dimensional accuracy and decreased the impact strength.

Due to the low mechanical performances of 3D-printed denture base resins, ZrO2 nanoparticles (ZrO2NPs) were incorporated into different 3D-printed resins and their effects on the flexure strength, elastic modulus, impact strength, hardness, and surface roughness were evaluated. A total of 286 specimens were fabricated in dimensions per respective test and divided according to materials into three groups: heat-polymerized as a control group and two 3D-printed resins (NextDent and ASIGA) which were modified with 0.5 wt.%, 1 wt.%, 3 wt.%, and 5 wt.% ZrO2NPs. The flexure strength and elastic modulus, impact strength, hardness, and surface roughness (µm) were measured using the three-point bending test, Charpy’s impact test, Vickers hardness test, and a profilometer, respectively. The data were analyzed by ANOVA and Tukey’s post hoc test (α = 0.05). The results showed that, in comparison to heat-polymerized resin, the unmodified 3D-printed resins showed a significant decrease in all tested properties (p < 0.001) except surface roughness (p = 0.11). In between 3D-printed resins, the addition of ZrO2NPs to 3D-printed resins showed a significant increase in flexure strength, impact strength, and hardness (p < 0.05) while showing no significant differences in surface roughness and elastic modulus (p > 0.05). Our study demonstrated that the unmodified 3D-printed resins showed inferior mechanical behavior when compared with heat-polymerized acrylic resin while the addition of ZrO2NPs improved the properties of 3D-printed resins. Therefore, the introduced 3D-printable nanocomposite denture-base resins are suitable for clinical use.

ZrO2 nanoparticles (ZNPs) have excellent physical properties. This study investigated the fracture load of implant-supported, fixed cantilevered prosthesis materials, reinforced with ZNPs and various polymerization techniques, compared with conventional and CAD/CAM materials. Sixty specimens were made from two CAD/CAM; milled (MIL) (Ceramill TEMP); and 3D-printed (NextDent Denture 3D+). Conventional heat-polymerized acrylic resin was used to fabricate the other specimens, which were grouped according to their polymerization technique: conventionally (HP) and autoclave-polymerized (AP); conventionally cured and reinforced with 5 wt% ZNPs (HPZNP); and autoclave reinforced with 5 wt% ZNPs (APZNP). The specimens were thermocycled (5000 cycles/30 s dwell time). Each specimen was subjected to static vertical loading (1 mm/min) using a universal Instron testing machine until fracture. Scanning electron microscopy was used for fracture surface analyses. The ANOVA showed significant fracture load differences between all the tested groups (p = 0.001). The Tukey post hoc tests indicated a significant difference in fracture load between all tested groups (p ˂ 0.001) except HP vs. HPZNP and AP vs. MIL. APZNP had the lowest mean fracture load value (380.7 ± 52.8 N), while MIL had the highest (926.6 ± 82.8 N). The CAD/CAM materials exhibited the highest fracture load values, indicating that they could be used in long-term interim prostheses. Autoclave polymerization improved fracture load performance, whereas ZrO2 nanoparticles decreased the fracture load performance of cantilevered prostheses.