Zirconia Powders Research Articles

Synthesis and assessment of properties of ZrB2 nanopowder utilizing boro/carbothermal reduction method

AbstractThe reason of this study is to synthesize ZrB2 nano powder utilizing boric acid and phenolic resin. Within the study of zirconia as a source of zirconium, boric acid was used as a source of boron and phenolic resin as a carbon source. The theoretical and experimental studies of ZrB2 were synthesized by boro/carbothermal diminishment from the novel sol–gel technology. The zirconia powder was crushed for 8 h and in conjunction with different molar proportions of boric acid, in this consider, a kinetic demonstrate for reactions creating ZrB2 was built up based on thermodynamic analysis. The resultant powder was synthesized in a neutral atmosphere controlled in 1450°C and 1550°C. After it was also observed that, with the increase of molar proportion of H3BO3, the reaction delivered ZrB2 powders in high amount of the boron reaction. The compound was analyzed by an X‐ray diffraction technique and found to be ZrB2 powder that was synthesized with the purity of approximately 98%.

Additively Manufactured Zirconia for Dental Applications with In Situ Color Gradation Control.

The current process for creating zirconia reconstructions for teeth is time-consuming, expensive, and results in tool wear and raw material waste. An alternative method, near-net shape additive manufacturing capable of producing samples with color gradient is presented as an innovative and more efficient solution. A low-cost robocasting system, which enabled the co-extrusion of two different ceramic inks, was designed and developed. Moreover, hydrogel-based ceramic inks, with rheological properties suitable for the present system, containing commercially available Yttria-stabilized zirconia (white and yellow) powders, were produced. Parts of different color shades and color gradients, with a high aspect ratio and good green body stability, were printed. In addition, precise color measurements were carried out, and co-extruded parts were compared with ultraviolet-C photofunctionalized parts. High fractions of binder in green bodies caused distortions in the samples during air drying and upon sintering. Debinding and sintering at 1500°C yielded parts of relatively low density (4.90-5.09 g/cm3) and hardness (500 HV10-1100 HV10). A slightly different sintering behavior was observed for parts of different compositions. Density and hardness increased with the fraction of iron oxide-containing ink.

Optimal Sensor Deployment for Parameter Estimation Precision by Integrating Bayesian Networks in Wet-Grinding Systems

Accurately and efficiently determining a system’s physical variables is crucial for precise product-quality control. This study proposes a novel method for optimal sensor deployment to increase the accuracy of sensing data for physical variables and ensure the timely detection of the product’s particle size in a wet-grinding system. This approach involves three steps. First, a Bayesian network (BN) is designed to model the cause–effect relationship between the physical variables by applying the path model. The detectability is determined to confirm that the mean shifts of all the physical variables are identifiable using sensor sets in the wet-grinding system. Second, the sensing location of accelerometers mounted on the chamber shell is determined according to the coupled computational fluid dynamics–discrete element method simulations. Third, the shuffled frog leaping algorithm is developed by combining the BN to minimize the maximum data output deviation index among all sensor sets and sensory costs; this is achieved under the constraints of the mean shift detectability, achieving optimum sensor allocation. Subsequently, a case study is performed on a zirconia powder production process to demonstrate that the proposed approach minimizes the requirements of the data output deviation index, sensory costs, and detectability. The proposed approach is systematic and universal; it can be integrated into monitor architecture for parameter estimation in other complex production systems.

Surface modification toughening of partially stabilized zirconia ceramics: by sub-eutectoid solution annealing

In this investigation, surface modification toughening of partially stabilized zirconia ceramics, by sub-eutectoid solution annealing, has been performed. The Zr0.918Mg0.068Y0.014O1.925 designated (MZY) was prepared by mixing Magnesia Partially Stabilized Zirconia (MZ9) and Yttria Tetragonal Zirconia (TZ3Y) Polycrystal commercial powders using wet ball milling. The mechanical properties and microstructure of the MZY were investigated. XRD and SEM were used for phase analysis and microstructure examination of the sintered samples’ surfaces. The fracture toughness and hardness of the sintered compacts were determined by the Vickers indentation technique. The physical and mechanical properties of MZY were compared to those of MZ9 ceramics prepared under the same conditions. The results showed that, the Yttria addition inhibited the exaggerated growth of the tetragonal precipitates during sintering. The MZY showed a maximum in the fracture toughness of 12.9 MPa√m upon sub-eutectoid solution annealing at 1000 °C for 150 h, while the tetragonal precipitates in the MZ9 lost coherence due to their spontaneous massive transformation to the monoclinic phase via the decomposition reaction.

Nonthermal atmospheric pressure plasma jet-assisted formation of oxygen vacancies stabilized tetragonal zirconia particles

This study presented a controlled oxygen vacancy formation on stabilization of tetragonal zirconia particles via a nonthermal atmospheric pressure plasma jet (APPJ) with varying the supplied power. The characteristic analyses based on X-ray diffraction, field emission scanning electron microscopy, high-resolution transmission electron microscopy (HR-TEM), Raman, ultraviolet–visible spectroscopy, and ultraviolet photoemission spectroscopy confirm the existence of oxygen vacancies in tetragonal zirconia particles. Production of oxygen vacancies in the prepared zirconia powder is related to the presence of surface defects by observing HR-TEM and further decreases the bandgap as indicated by optical characterization. Thus, it can be anticipated that the research of defect engineering is a promising way to improve the optoelectronic and photocatalytic performance of oxide material via the APPJ method.

Nano-dispersed yttria-stabilized zirconia powder: Phase, morphology, and conductivity investigation with different chelating agents via a modified sol-gel method

8 mol% yttria-stabilized zirconia nano-powders were synthesized via a novel sol–gel method employing basic zirconium carbonate, acetic acid, and different chelating agents (citric acid, oxalic acid, and ethylenediaminetetraacetic acid (EDTA)). The dried gel and calcined nano-powders were characterized using various techniques to investigate their thermal behavior, phase composition, particle size, microstructure morphology, and electrochemical performance. It was found that the dried gel had different polymeric network structures based on the different molecular structures, number of functional groups, and acidity of the chelating agents, which led to different properties after calcination. The smallest particle size, best dispersion, and narrowest grain size distribution were obtained for the EDTA sample after calcination at 600 °C, which are attributed to the unique functional groups in EDTA. The highest relative density and smallest grain size of the EDTA sample, which resulted in enhanced grain boundary contribution and effective conducting area, led to increased ionic conductivity (0.06 S cm−1).

Preparation, Characterization and Properties of NC-coated Zirconium Composite Particles

Zirconium has certain application advantages compared with other metals due to its high density, high volume calorific value and combustion performance. Unfortunately, the applications of current Zirconium powders are limited due to its high electrostatic discharge sensitivity, making Zirconium powders more pyrophoric and less amenable to functionalization. To improve the security, Zr/NC composite particles with reduced electrostatic discharge sensitivity are prepared by solvent-antisolvent method and characterized by FT-IR, XRD, TG, SEM and ESD test. The measurement confirmed that the 50% firing energy (E50) of Zr/NC is increased from 5.13 mJ to 25.2 mJ, which is 5 times higher than that of raw Zr powder. The results show that surface coating modification is a feasible method for decreasing the ESD of Zr powder. This study provides technology support for its application in high density propellant.

Contents

International Journal of Applied Ceramic TechnologyVolume 20, Issue 4 p. 2043-2046 ISSUE INFORMATIONFree Access Contents First published: 31 May 2023 https://doi.org/10.1111/ijac.14090AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Graphical Abstract Cover Photograph: Yttria-stabilized zirconia (YSZ) powder with surface Ni plating has promising application in many fields. The cover image shows the progression of electroless nickel deposition on hollow spherical YSZ from uncoated materials (top row) through 120 minutes of deposition time. Read more about the experiments and kinetic modeling of this study in https://doi.org/10.1111/ijac.14347 Volume20, Issue4July/August 2023Pages 2043-2046 RelatedInformation

Wear behaviour of alumina-toughened-zirconia composites with different phase arrangement under ball-on-flat tribological tests

ABSTRACT An alumina-toughened zirconia (ATZ) material, fabricated using a procedure consisting of the common sintering of two different zirconia powders, was tested using the ball-on-disc method in a temperature range between room temperature and 400°C. Tetragonal zirconia balls were used as a counterpart. Two different types of microstructure were designed, one consisting of separated alumina inclusions in a zirconia matrix and another one which was a combination of two continuous phases, penetrating the whole volume of the composite. It was detected that at elevated temperatures both materials showed a distinct decrease in the wear rate. Composite with a low alumina content showed minimal wear rate at 300°C and composite with higher amount of alumina showed it at 400°C. There are some observations that this minimal wear rate result is connected with a pseudoplastic behaviour of a layer formed between co-operating elements of tribological pair. This layer is composed of the debris of both, sample and counterpart, and its behaviour during sliding is connected with the mean grain size of this debris which is correlated with the mean grain size of sintered material.

Impact Strength of Various Types of Acrylic Resin: An In Vitro Study.

The aim of this study is to evaluate and compare the impact strength of conventional acrylic resin, high-impact acrylic resin, high-impact acrylic resin reinforced with silver nanoparticles, and high-impact acrylic resin reinforced with a zirconium oxide powder. A total of 60 samples were prepared of dimensions 60 mm length × 7 mm width × 4 mm thickness to test impact strength. Machined stainless steel dies of the same dimension were used to form molds for the fabrication of these samples. Of 60 samples, 15 samples were prepared each from conventional acrylic resin (Group A1), high-impact acrylic resin (Group A2), acrylic resin reinforced with silver nanoparticles (Group A3), and acrylic resin reinforced with zirconium oxide powder (Group A4). Izod-Charpy pendulum impact testing machine was used. The impact strength of group A1 was in the range of 2.83-3.30 kJ/m2 (M = 3.12 kJ/m2, SD = 0.16), group A2 was in range of 5.10-5.78 kJ/m2 (M = 5.51 kJ/m2, SD = 0.18), group A3 was in range 3.18-3.56 kJ/m2 (M = 3.37 kJ/m2, SD = 0.11), and group A4 was in range 7.18-7.78 kJ/m2 (M = 7.5 kJ/m2, SD = 0.18). Statistical analysis using one-way ANOVA and t-test revealed significant differences (p < 0.001). High-impact acrylic resin reinforced with zirconium oxide powder has the highest impact strength. This research sheds light on the usefulness of novel filler materials in clinical prosthodontics.

ОПРЕДЕЛЕНИЕ УДЕЛЬНОЙ ПОВЕРХНОСТИ ПОРОШКОВ ЦИРКОНИЯ МЕТОДОМ НИЗКОТЕМПЕРАТУРНОЙ АДСОРБЦИИ АЗОТА

The work is devoted to determination of the specific surface of fine-dispersed zirconium powders of different producers by low-temperature nitrogen adsorption method using modern analytical equipment. Sodium-reduced zirconium powders of two different productions, as well as coarse electrolytic zirconium powder after its grinding by hydride technology, were researched in the present work. Consequently the values of the specific surface of the studied zirconium powders by the BET method were obtained, and features of such measurements by “Sorbtometr-M002” evaluator for the specified materials were noted.

ПРИКЛАДНОЕ МАТЕРИАЛОВЕДЕНИЕ ПОРОШКОВ ЦИРКОНИЯ

The research is dealing with the necessity of substitution of zirconium powder, which was previously produced by “factory No. 1”, for the one made by “factory No. 2”. In the course of our work, which is preceding the implementation of the second kind of powder, we have found some differences in the properties of the powders of different origins. Our goal was to use the methods of studying surface, structure, chemical and phase composition and to find the cause of such discrepancy in properties and present a new way to eliminate them. The analysis of the results of the research allowed us to summarize the ways of improving the technology used on “factory No. 2” and creating the alternative ways of obtaining zirconium powder.

ИЗУЧЕНИЕ ПРОЦЕССОВ АГРЕГИРОВАНИЯ И ДЕЗАГРЕГИРОВАНИЯ ЧАСТИЦ ВЫСОКОДИСПЕРСНОГО ПОРОШКА ЦИРКОНИЯ

During long-term storage of wet fine zirconium metal powder under certain conditions the process of particles aggregation may start, which leads to powder transformation into a solid lumpy material, which significantly limits its application range. The purpose of this work was to establish the probable causes leading to the aggregation of zirconium powder particles during long-term storage, and to assess the possibility of transferring the lumpy material to its initial powdery state while preserving its basic physical and chemical properties. Particles aggregation most likely happens due to participation of zirconium atoms of the metal layers in formation of oxo-bridging bonds in acidic medium. Lumpy material formed in the process of storage of sodium-thermal zirconium metal powder (PZrN-A) was used as an example for testing the method of particles disaggregation by means of sodium hydroxide solution treatment, which makes it possible to transform the lumpy material into a stable powdery state typical for standard powder. The mechanism of alkaline treatment consists in the irreversible rupture of oxo-bridging bonds in the material, and the formation of hydroxyl groups on the surface of zirconium particles, which is accompanied by the destruction of aggregates and their disintegration into individual particles. Treatment with sodium hydroxide solution of different concentration demonstrates no significant changes in chemical composition of particles surface layers and makes it possible to maintain the main physical and chemical characteristics of zirconium powder. Samples of zirconium powder were studied by scanning electron microscopy, X-ray spectral microanalysis. The content of total and active zirconium, the value of the specific surface area of the powders was determined. Their sensitivity to friction and electric spark is evaluated.

DLP 3D printing of high strength semi-translucent zirconia ceramics with relatively low-loaded UV-curable formulations

DLP 3D printing is one of the additive manufacturing techniques, which allows the fabrication of ceramic parts with a complex shape, precisely controlled internal architecture and fine surface finishing. The method is based on the layer-by-layer solidification of a photosensitive ceramic suspension via UV-light projection followed by debinding of organic components and sintering and generally requires a high solid content of the ceramic filler to achieve good sintered densification. The present article aims to explore the possibility of fabricating high strength, fully dense and semi-translucent zirconia parts with relatively low-loaded UV-curable systems using a low-cost desktop DLP printer designed for printing polymers. For the slurry preparation, tetragonal zirconia powders from three different suppliers were evaluated. It was shown that with 35 vol% of zirconia content slurries, it was possible to fabricate zirconia semi-translucent ceramics with a density of 99.6%. No cracks or pores larger than 1 μm were observed on the sintered parts. According to ball-on-3-ball mechanical tests performed on the 13 × 1 mm discs an average flexural strength of the printed zirconia ceramics was 1566 MPa and a maximum of 1964 MPa could be achieved.

A further step toward the understanding of phase transformation mechanism between 10 wt. % dysprosia stabilized zirconia powders and ceramics

In this study, 10 wt. % dysprosia stabilized zirconia (10DySZ) ceramics were prepared by pressing and pretreatment method. The phase and structural evolution as well as the phase transformation behaviors of 10DySZ ceramics were investigated. Results show that the 10DySZ ceramics have the same phase composition as that of powders in final products. Differently, an asynchronous nucleation behavior of m- and c-DySZ can be recognized, the t→m martensite transformation was inhibited significantly during the incubation period of phase transformation. The phase transformation behaviors of 10DySZ ceramics were also confirmed to be followed the new phase nucleation and growth theory. In the early stage, the inhibition of phase transformation can be attributed to the comprehensive influence from steric hindrance, internal stress and critical size effect. However, in the later phase transformation explosion period, the rapid growth of new phases as well as the increased internal stress dominated the acceleration of phase transformation of 10DySZ ceramics.

Expression of Interleukin-1β and Histological Changes of the Three-Dimensional Oral Mucosal Model in Response to Yttria-Stabilized Nanozirconia.

Over the years, advancement in ceramic-based dental restorative materials has led to the development of monolithic zirconia with increased translucency. The monolithic zirconia fabricated from nano-sized zirconia powders is shown to be superior in physical properties and more translucent for anterior dental restorations. Most in vitro studies on monolithic zirconia have focused mainly on the effect of surface treatment or the wear of the material, while the nanotoxicity of this material is yet to be explored. Hence, this research aimed to assess the biocompatibility of yttria-stabilized nanozirconia (3-YZP) on the three-dimensional oral mucosal models (3D-OMM). The 3D-OMMs were constructed using human gingival fibroblast (HGF) and immortalized human oral keratinocyte cell line (OKF6/TERT-2), co-cultured on an acellular dermal matrix. On day 12, the tissue models were exposed to 3-YZP (test) and inCoris TZI (IC) (reference material). The growth media were collected at 24 and 48 h of exposure to materials and assessed for IL-1β released. The 3D-OMMs were fixed with 10% formalin for the histopathological assessments. The concentration of the IL-1β was not statistically different between the two materials for 24 and 48 h of exposure (p = 0.892). Histologically, stratification of epithelial cells was formed without evidence of cytotoxic damage and the epithelial thickness measured was the same for all model tissues. The excellent biocompatibility of nanozirconia, as evidenced by the multiple endpoint analyses of the 3D-OMM, may indicate the potential of its clinical application as a restorative material.

Kinetic stability and rheological properties of photosensitive zirconia suspensions for DLP printing

Digital light processing (DLP) is a rapidly developing technology accessing the opportunity to print complex ceramics objects. The main prerequisite for successful printing is the preparation of kinetically stable suspension with low viscosity and homogenous distribution of perfectly dispersed particles. All three mentioned assumptions could be fulfilled by a selection of a suitable dispersant and starting zirconia powder. In this paper, a commercial agent Disperbyk-103 was used to create a highly stable suspension with 30 vol% of zirconia powder with appropriate viscosity (0.93 Pa s at a shear rate of 10 s−1). The optimal concentration of the agent was set not only by rheological measurements but also with the help of measurement of the kinetic stability over time using an analytical centrifuge. Stability measurement was evaluated as an appropriate supplementary analysis to the conventional viscosimetric analysis. Furthermore, the predictive viscosity models were tested either as a tool how to estimate the maximum solid volume fraction for the ceramic suspensions as well as for the prediction of suspension dynamic viscosity according to the used solid content in the prepared suspension. Finally, the suspension with the most suitable physicochemical properties was printed, sintered, and subsequently characterized using the analysis of mechanical properties by the Vickers hardness (1315 HV), relative density (98.2%) and shrinkage. The presented work points to the excellent possibility of using stability analysis as a complementary ceramic suspension analysis.

Colloidal Processing and Sintering of Alumina and Zirconia Fine Particles Using New Microbial Dispersant

Application of new microbial dispersant to colloidal processing of fine powders of zirconia and alumina was conducted for obtaining fine-grained microstructures. Well-dispersed aqueous suspensions of the fine powders were prepared by adding appropriate amount of new microbial dispersant. The suspensions were characterized by measuring particle size, zeta-potential and rheological properties. Dense green bodies of zirconia and alumina were obtained by slip casting of the suspensions and further CIP treatment. Low-temperature densification was observed, and dense and fine-grained sintered bodies were obtained.

YSZ/Ni double‐shell powder via surface electroless deposition tuned by an active kinetic model

AbstractYttria‐stabilized zirconia (YSZ) powder with surface Ni plating has promising application in many fields due to its large surface area, low density and excellent high temperature performance. In this study, YSZ/Ni double‐shell powder was fabricated via electroless deposition method, and an active surface kinetic model was developed to tune the surface area and nuclei loading quantitatively. A novel concept, active surface ratio (ASR, the ratio of active deposition surface area to projected area of ceramic powder), is proposed to intrinsically correlate deposition rate with nuclei topology on ceramic surface. The intrinsic relationship between microstructure of metallized ceramic surface and deposition duration was clarified. The active surface kinetic model reveals the correlation between the ASR and instantaneous deposition rate and provides necessary theoretical basis for effective control of ceramic surface modification process by electroless deposition.

Cracking Behavior of Atmospheric Plasma-Sprayed 8YSZ Thermal Barrier Coatings during Thermal Shock Test

The failure of plasma-sprayed thermal barrier coatings (TBCs) during service is usually related to the cracking behavior. In this study, plasma-sprayed TBCs were prepared with two kinds of agglomerated sintered yttria-stabilized zirconia (YSZ) powders with different particle sizes. The evolution of mechanical properties and crack propagation behavior of the coatings during the whole life stage were studied by a thermal shock test. The effect of powder particle size on the cracking behavior of the TBCs during thermal shock was analyzed from the aspect of pore structure, mechanical properties, and stress state of the coatings. The crack propagation and coalescence in the direction parallel to the substrate in the coating is the main factor leading to the spalling failure of the coating during thermal shock. Although the coating prepared by fine YSZ has higher fracture toughness, the lower strain tolerance will increase the cracking driving force on the crack tip of the coating during thermal shock, and the cracks in the coating propagate merge at a faster rate during thermal shock. The larger porosity and pore size of the coating prepared by coarse YSZ help the coating suffer less thermal stress during thermal shock. Although the existence of pores reduces the fracture toughness of the coating to a certain extent, the increase of strain tolerance reduces the crack growth rate in the coating, so the coating has a longer life.