Zirconia Particles Research Articles

Zirconia Fiber Containing TRIP‐Matrix Composites Prepared via Paper‐Manufacturing Technology

Herein, the continuous further development of metal matrix composites prepared by the paper‐manufacturing technology is in focus. The composites are based on metastable austenitic stainless steel with the addition of magnesia partially stabilized zirconia particles or yttria‐stabilized zirconia fibers. The sintering conditions are profoundly investigated, to study and subsequently inhibit the formation of carbides, which deteriorates the mechanical performance of the paper‐derived materials in the past. The cellulose pulp fiber content as well as the filler particle content is adjusted with the aim to improve the mechanical performance of the paper‐derived materials during tensile load testing. In addition, the cellulose pulp fibers are partially replaced by yttria‐stabilized zirconia fibers. The improved composites that contain 3 and 6 vol% of yttria‐stabilized zirconia fibers exhibit the ultimate tensile strengths of 264 and 322 MPa. The tensile strain of the improved TRIP‐matrix composites as well as of the reference material is significantly increased (up to 10%) as compared with our previous study, where all materials show brittle fracture behavior. This can certainly be attributed to the improvements in the sintering process and the corresponding prevention of carbide formation during heat treatment upon cooling.

Mechanical Properties of Nanohybrid Resin Composites Containing Various Mass Fractions of Modified Zirconia Particles.

PurposeThe aim of this study was to investigate the effect of various mass fractions of 10-methacry-loyloxydecyl dihydrogen phosphate (MDP)-conditioned or unconditioned zirconia nano- or micro-particles with different initiator systems on the mechanical properties of nanohybrid resin composites.MethodsBoth light-cured (L) and dual-cured (D) resin composites were prepared. When the mass fraction of the nano- or micro-zirconia fillers reached 55 wt%, resin composites were equipped with dual-cured initiator systems. We measured the three-point bending-strength, elastic modulus, Weibull modulus and translucency parameter of the nanohybrid resin composites containing various mass fractions of MDP-conditioned or unconditioned zirconia nano- or micro-particles (0%, 5 wt%, 10 wt%, 20 wt%, 30 wt% and 55 wt%). A Cell Counting Kit (CCK)-8 was used to test the cell cytotoxicity of the experimental resin composites. The zirconia nano- or micro-particles with MDP-conditioning or not were characterized by transmission electron microscopy (TEM), Fourier infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS).ResultsResin composites containing 5–20 wt% MDP-conditioned or unconditioned nano-zirconia fillers exhibited better three-point bending-strength than the control group without zirconia fillers. Nano- or micro-zirconia fillers decreased the translucence of the nanohybrid resin composites. According to the cytotoxicity classification, all of the nano- or micro-zirconia fillers containing experimental resin composites were considered to have no significant cell cytotoxicity. The FTIR spectra of the conditioned nano- or micro-fillers showed new absorption bands at 1719 cm−1 and 1637 cm−1, indicating the successful combination of MDP and zirconia particles. The XPS analysis measured Zr–O–P peak area on MDP-conditioned nano- and micro-zirconia fillers at 39.91% and 34.89%, respectively.ConclusionNano-zirconia filler improved the mechanical properties of nanohybrid resin composites, but cannot be the main filler to replace silica filler. The experimental dual-cured composites can be resin cements with better opacity effects and a low viscosity.

Investigation of two-body wear behavior of zirconia-reinforced lithium silicate glass-ceramic for biomedical applications; in vitro chewing simulation

The aim of this work was to the investigate two-body wear behavior of zirconia-reinforced lithium silicate glass-ceramic and composite resins through in vitro chewing simulation. Two types of glass-ceramics (IPS e.max CAD; lithium disilicate, Vita Suprinity; zirconia-reinforced lithium silicate) and two types of composite resins (Filtek Supreme; nano-filled, Ivoclar Vivadent Heliomolar; micro-filled) were used. All specimens were exposed to two-body wear tests using a dual-axis computer-controlled chewing simulation. Each chewing simulation test procedure, Al2O3 ball with a diameter of 6 mm, was used as antagonist material. The mean volume loss and wear depth of all specimens after the chewing tests were determined with use non-contact 3 D profilometer. Zirconia-reinforced lithium silicate Vita Suprinity had significantly higher two-body wear resistance than lithium disilicate IPS e.max CAD glass-ceramic and other composite resins after chewing tests. While Vita Suprinity exhibited a homogeneous crystal microstructure, IPS e.max CAD glass-ceramic exhibited a structure with needle-shaped fine-grained crystals embedded in a glassy matrix. As a result, the homogeneous distribution of zirconia particles into the ceramic material will increase the two-body wear resistance through chewing simulation tests.

Synthesis and Characterization of Monodisperse Hydrous Colloidal Zirconia Nanoparticles

The suspension of hydrous colloidal zirconia particles (CZPs) was prepared from zirconium oxychloride solutions via thermal hydrolysis at acidic condition and at boiling point of 110 ºC for 72 h. Characterization of the obtained suspension and dried solid ZrO2 was performed by DLS, FESEM, FTIR, XRD and TGA measurements. Purification via dialysis membrane can maintain the monodispersion of the colloidal suspension when stabilized at pH6. The suspension contained almost sheet-like colloidal particles with amorphous structure with size ranges from 70 to 140 nm in wide and about 40-60 nm in thickness. The formula of hydrous CZPs can be expressed as ZrO2.2H2O.

Early Short-Term Postoperative Mechanical Failures of Current Ceramic-on-Ceramic Bearing Total Hip Arthroplasties.

Although ceramic-on-ceramic (CoC) bearings have been shown to produce the smallest amount of wear volume in vitro as well as in vivo studies when used for total hip arthroplasties (THA), concerns about the failure of these bearing surfaces persist due to early failures observed after short postoperative time. In this study, an exhaustive analysis of the early failure occurred on the new generation of ceramic bearings, consisting of a composite alumina matrix-based material reinforced with yttria-stabilized tetragonal zirconia (Y-TZP) particles, chromium dioxide, and strontium crystals, was performed. For this study, 118 CoC bearings from 117 patients were revised. This article describes a group of mechanical failure CoC-bearing BIOLOX THA hip prosthesis patients without trauma history. The retrieved samples were observed under scanning electron microscopy (SEM), composition was analyzed with energy dispersive X-ray spectroscopy (EDX), and damaged surfaces were analyzed by grazing-incidence X-ray diffraction (GI-XRD) and white light interferometry. In the short term, CoC articulations provided similar mechanical behavior and functional outcome to those in XLPE cases. However, 5% more early mechanical failures cases were observed for the ceramic components. Although the fracture rate of third generation CoC couples is low, the present study shows the need to further improve the third generation of CoC-bearing couples for THA. Despite the improved wear compared to other materials, stress concentrators are sources of initial crack propagation, such as those found in the bore-trunnion areas. Moreover, in view of the evidence observed in this study, the chipping observed was due to the presence of monoclinic phase of the Y-TZP instead of tetragonal, which presents better mechanical properties. The results showed that total safety after receiving a THA is still a goal to be pursued.

Fast synthesis of novel micron porous particles of Gd, Yb and Y-stabilized zirconia to prepare TBCs with low thermal conductivity

The conventional agglomerated and sintered (A&S) zirconia granules for making plasma-spraying thermal barrier coatings (TBCs) was dense and nonporous. A novel porous A&S zirconia granule was reported in this work. Firstly, some novel porous spherical particles (about 1 μm) of zirconia partially stabilized by Gd, Yb and Y (Gd-Yb-YSZ) were synthesized by a new method using the carbon spheres as the templates. This made the subsequent liquid-solid separation by filtration much faster than the conventional sol-gel method. Then these micron porous Gd-Yb-YSZ particles were transformed to some big porous granules (30–90 μm) by a A&S method. Finally, these porous Gd-Yb-YSZ granules were used to make a novel porous TBC of Gd-Yb-YSZ on superalloy by air plasma spray, together with the nonporous granules of both Gd-Yb-YSZ and YSZ. The measured insulation temperatures of TBCs made from the nonporous YSZ granules, the nonporous Gd-Yb-YSZ granules and the porous Gd-Yb-YSZ granules were 45 °C, 59 °C and 94 °C, respectively, at a heat source temperature of 1050 °C. It indicated that the thermal conductivity of TBC decreased in the following order: nonporous YSZ granule specimen > nonporous Gd-Yb-YSZ granule specimen > porous Gd-Yb-YSZ granule specimen. The possible reasons for this result were investigated.

Wear debris released by hip prosthesis analysed by microcomputed tomography.

Total hip arthroplasty uses commercial devices that combine different types of biomaterials. Among them, metals, ceramics and metal oxides can be used either in the prosthesis itself or in the cement used to anchor them in the bone. Over time, all of these materials can wear out and release particles that accumulate in the periprosthetic tissues or can migrate away. We used histology blocks from 15 patients (5 titanium metallosis, 5 alumina prostheses, 5 with altered methacrylic cement) to perform a microCT study and compare it with conventional histology data. An EDS-SEM analysis was done to characterise the atomic nature of the materials involved. A morphometric analysis was also performed in 3D to count the particles and assess their density and size. The metallic particles appeared to be the largest and the ceramic particles the finest. However, microCT could not reveal the wear particles of radiolucent biomaterials such as polyethylene and the very fine zirconia particles from cement fragmentation. MicroCT analysis can reveal the extent of the accumulation of these debris in the periprosthetic tissues. LAYOUT DESCRIPTION: Hip prostheses progressively degrade in the body by releasing wear debris. They accumulate in the periprosthetic tissues. Microcomputed tomography was used to image three types of radio-opaque wear debris: metal, ceramic and zirconia used in the bone cements.

In-vitro mechanical and biological evaluation of novel zirconia reinforced bioglass scaffolds for bone repair

Bone defects resulting from infections, tumors, or traumas represent a major health care issue. Tissue engineering has been working togehter with medicine to develop techniques to repair bone damage and increase patient's life quality. In that context, scaffolds composed of bioactive ceramics have been explored, although their poor mechanical properties restrain their clinical applications as highly porous structures. As an alternative solution, this study aimed to evaluate the mechanical properties and biological response of novel zirconia reinforced bioactive glass scaffolds (ZRBG) manufactured by the replica method. The microstructure, chemical composition, compressive strength, density, in-vitro bioactivity, and cell viability were analyzed and compared to scaffolds made of monolithic zirconia of similar architecture (45, 60 and 85 ppi). The microstructure of ZRGB scaffolds consisted of a bioactive glass matrix with dispersed zirconia particles (~33% glassy phase) and the compressive strength values (ZRBG scaffolds: 0.33 ± 0.11, 0.41 ± 0.20 and 0.48 ± 0.6 MPa; ZRBG scaffolds with extra BG coating: 0.38 ± 0.13, 0.45 ± 0.11 and 0.50 ± 0.14 MPa for 45, 60 and 80 ppi, respectively) were not statistically different from those of zirconia scaffolds (0.25 ± 0.14 MPa for 45 ppi, 0.32 ± 0.11 MPa for 60 ppi and 0.44 ± 0.07 MPa for 80 ppi). No bioactivity was exhibited by monolithic zirconia scaffolds while significant bioactive response was found for ZRBG scaffolds. The cell viability of ZRBG scaffolds in osteogenic medium was improved up to 171% over zirconia scaffolds. This work provides promosing results for further exploring this technique for implant dentistry.

Synthesis and Properties of Heat Resistant Coatings Based on a Si–B4C–ZrB2–ZrO2 Composition

This article discusses the influence of nanosized particles of zirconium dioxide on the properties of a heat-resistant coating synthesized by the suspension annealing of a silicon–boron carbide–zirconium diboride composition. The heat resistance of coatings on graphite and high silica ceramic substrates is studied, and the phase composition, morphology, hardness, and electric resistance of the coatings are determined.

Influence of wet foam stability on the microstructure of ceramic shell foams

In this study, recycled ceramic shell particles from the mold used in precision casting, which consists of coating a wax model with several layers (shell) of mullite and zirconia particles of different sizes, were used as raw material to prepare stable wet-foams by direct foaming and gelcasting using ovalbumin. The control of suspension parameters, such as pH, dispersant concentration, solids concentration and stirring velocity, can influence the foam stability against destabilization mechanisms (such as drainage, coalescence, and Ostwald ripening), optimizing the final properties of the cellular ceramic structures. The rheological behavior of suspensions and the gel point temperature of foams was also evaluated. The evolution of the bubbles-sizes (as a function of time) into the wet foam structure was analyzed by Axio Vision LE and ImageJ software. The fired ceramic shell foam (1550 ​°C, 2 ​°C/min, for 2 ​h) exhibited porosities higher than 80%, characterized by a highly interconnected network of spherical pores, with sizes ranging from 518 ​± ​29 to 1088 ​± ​103 ​μm and compressive strength of 0.9 ​± ​0.2 ​MPa. The morphological features and mechanical strength of the obtained foam indicating the possibility that it could be employed as low-cost replacement for radiant porous burners applications.

Effect of Zr/Gnp hybrid filler on thermal and ablation properties of carbon‐epoxy composites

AbstractIn this work, the Zirconia (Zr) particles were coated with graphene nanoplatelets (Gnps) using the wet chemical synthesis process and sintered at 500°C and 900°C. At sintering temperature of 900°C, the Zr coated with 0.25 wt% Gnp fillers exhibited better oxidation resistance. Thus, the carbon epoxy (C‐Ex) composites containing Zr/Gnp, 0.25 wt%, were fabricated by the hand‐layup technique. The prepared composites were characterized by scanning electron microscopy, thermogravimetry analysis (TGA), flexural, and ablation tests. The C‐Ex composites modified with Zr/Gnps fillers showed significant improvement in thermal stability and flexural strength compared with the pristine sample. The composite containing 0.25 wt% Zr/Gnp filler reduced the mass ablation rate to 23%, whereas back‐surface temperature was decreased to 170°C compared with pure C‐Ex composite. The surface morphology of ablated composite samples revealed that the Zr/Gnp produced char droplet spheres on the carbon fibres, which prevented the further oxidation of the matrix and thus improved the ablative performance.

A new holder/container with a porous cover for atomic layer deposition on particles, with transport analysis and detailed characterization of the resulting materials

Atomic layer deposition (ALD) is widely used in the semiconductor and materials industries for depositing thin films. Here, we describe a holder/container for performing ALD on particles that does not require agitation. This device contains a broad, shallow, circular recess that holds the particles. Two different frits and combinations of stacked meshes were explored as a cover to this holder to restrict the movement of the particles while still allowing good conductance of the ALD reagent gases. A mathematical discussion of the diffusion through the frits and stacked meshes is presented. As confirmed by spectroscopic ellipsometry (SE) on planar witness silicon shards, consistent, high‐quality film growth took place inside and outside the holder. The performance of the holder was demonstrated with ~5‐μm zirconia particles that were coated with alumina from trimethylaluminum (TMA) and water, and with zinc oxide from diethylzinc (DEZ) and water. Deposition on different amounts of particles was investigated (50, 100, 200, and 500 mg). Parasitic chemical vapor deposition (CVD) appeared to be present when a greater number of particles or meshes were used. ALD coating on particles was also confirmed by X‐ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and energy‐dispersive X‐ray spectroscopy (EDS).

Microstructural, mechanical, and optical characterization of an experimental aging-resistant zirconia-toughened alumina (ZTA) composite

ObjectiveTo evaluate the effect of aging on the microstructural, mechanical, and optical properties of an experimental zirconia-toughened alumina composite with 80%Al2O3 and 20%ZrO2 (ZTA Zpex) compared to a translucent zirconia (Zpex) and Alumina. MethodsDisc-shaped specimens were obtained by uniaxial and isostatic pressing the synthesized powders (n = 70/material). After sintering and polishing, half of the specimens underwent aging (20 h, 134 °C, 2.2 bar). Crystalline content and microstructure were evaluated using X-ray diffraction and scanning electron microscopy, respectively. Specimens underwent biaxial flexural strength testing to determine the characteristic stress, Weibull modulus, and reliability. Translucency parameter (TP) and Contrast ratio (CR) were calculated to characterize optical properties. ResultsZTA Zpex demonstrated a compact surface with a uniform dispersion of zirconia particles within the alumina matrix, and typical alumina and zirconia crystalline content. ZTA Zpex and alumina exhibited higher CR and lower TP than Zpex. ZTA Zpex and Zpex showed significantly higher characteristic stress relative to alumina. While aging did not affect optical and mechanical properties of ZTA Zpex and alumina, Zpex demonstrated a significant increase in translucency, as well as a in characteristic stress. Alumina reliability was significantly lower than others at 300 MPa, ZTA Zpex and Zpex reliability decreased at 800 MPa, except for aged Zpex. SignificanceWhile aging did not affect the mechanical nor the optical properties of ZTA Zpex and alumina, it did alter both properties of Zpex. The results encourage further investigations to engineer ZTA as a framework material for long span fixed dental prostheses specially where darkened substrates, such as titanium implant abutments or endodontically treated teeth, demand masking.

A review on tribological behaviour and mechanical properties of Al/ZrO2 metal matrix nano composites

This article reviews the effects of nano-sized mono metallic zirconium oxide particles on the mechanical and the tribological behavior of aluminum alloys. The zirconium oxide nanoparticle plays a vital role in acts as reinforcements and aluminum alloys as base matrix. The fabrication of aluminum nano composites was prepared by adding various weight percentages of nano-sized zirconium oxide (ZrO2) nanoparticles in aluminum alloys by using stir casting techniques with a controlled environment. The outcomes were found by the previous literature review shows that the tribological behavior of the aluminum nanocomposite was enhanced the coefficient of friction and wear resistance related through base matrix and also improved mechanical properties such as ultimate tensile strength, impact strength, microhardness, the slight reduction in ductility and fracture toughness of the aluminum nanocomposites by accumulative volume percentage of zirconium oxide (ZrO2) nanoparticles. For microstructural analysis, concluded that the results were showing that the scattering of reinforcement distributions is uniform around the base matrix and an excellent bonding between them.

The effects of adding zirconium oxide Micro-particles to high impact polymethyl methacrylate on some mechanical properties

Aim: The purpose of this study was to investigate the transverse strength and impact strength of high impact heat-cured Poly (Methyl Methacrylate) (PMMA) reinforced with zirconium oxide particles (ZrO2). Materials and Methods: A total of sixty specimens were fabricated for each test. The denture base materials evaluated in this study were divided equally into three groups (A), (B) and (C) for each test. group (A) control group, unmodified high impact heat cured (PMMA). Group (B) ‎&‎ ‎(C) high impact heat cured (PMMA) reinforced with 5% ‎&‎ ‎10% (ZrO2) powder respectively by volume. The transverse strength was measured using the three point bending test. The impact strength was measured using the Chrapy impact tester. The micro-structural study of the fracture surfaces of test specimens ‎was performed using Scanning Electron Microscope. Results: Statistical analysis were conducted on the data obtained from the experiments using one way analysis of variance(ANOVA).Both ‎the transverse strength and impact strength of high impact heat cured PMMA reinforced with ‎treated ZrO2 particles were superior to the unreinforced high impact heat cured PMMA. However, the improvement in transverse strength was not directly proportional with the amount of filler particles. Scanning electron micrographs showed the degree of bonding between the filler particles and PMMA matrix.

Hip Spacers with a Metal-on-Cement Articulation Did Not Show Significant Surface Alterations of the Metal Femoral Head in Two-Stage Revision for Periprosthetic Joint Infection.

Two-stage revision is considered the gold standard treatment for chronic periprosthetic joint infection (PJI). During the interim period, between explantation of the infected hip endoprosthesis and revision arthroplasty, individually formed articulating hip spacers made of polymethylmethacrylate (PMMA) bone cement can be used to provide better soft tissue preservation, local antibiotic release, and improved postoperative mobilization. If effective prevention from luxation is achieved, hip function and hence overall patient satisfaction is improved. Zirconium oxide particles inside conventional PMMA bone cement, however, are known to enhance third-body wear, which may cause alterations of the metal head in the articulating spacer and hence become a serious risk for the patient. Therefore, the aim of our study was to analyze whether the articular surface of cobalt-chrome (CoCr) femoral heads is significantly altered in the setting of a metal-on-cement articulation during the interim period of two-stage revision for PJI. We analyzed a consecutive series of 23 spacer cases and compared them with femoral heads from two series of conventional hip arthroplasty revisions with metal-on-polyethylene articulations and different time intervals in situ. To investigate metallic wear, the femoral heads were thoroughly examined, and their surface roughness was measured and analyzed. We found no significant differences between the two conventional hip arthroplasty groups, despite their very different times in situ. Furthermore, the individually different times in situ within the spacer group had no significant impact on surface roughness, either. Compared with the spacer group, the surface roughness of the metal femoral heads from both conventional hip arthroplasty groups were even higher. Within the spacer group, roughness parameters did not show significant differences regarding the five predefined locations on the metal head. We conclude that metal-on-cement articulations do not cause enhanced surface alterations of the metal femoral head and hence do not limit the application in articulating hip spacers in the setting of two-stage revision for PJI.

Interface-by-design in zirconia-polyurea matrix hybrid composites

This study investigates the incorporation of zirconia particles in polyurea matrix to form hybrid composites. Pristine zirconia particles in the monoclinic phase are first premixed with an oligomeric diamine−a reactant for polyurea−as an alternative method of surface functionalization that does not require the use of organosilanes. Interfacial interactions between the zirconia particles and polyurea are revealed via attenuated total reflectance-Fourier transform infrared spectroscopy, where a shift and broadening of the urea-carbonyl stretching and an increase in relative intensity of the corresponding disordered vs. ordered N–H stretching are shown in hybrid composites vs. bulk polyurea. The composition dependence of the viscoelastic relaxation characteristics and dynamic storage modulus in hybrid composites as determined by dynamic mechanical analysis are also elaborated upon. Additionally, we evaluate the potential of exploiting zirconia-polyurea hybrids to enabling dynamic impedance optimization at the interface of a select bi-layer construct, particularly when considering the material response under dynamic loading environments.

Morphology and pore structure of zirconia particles prepared by the thermal treatment of zirconium tetra-n-propoxide in glycols

Morphology and pore structure of zirconia particles prepared by the thermal treatment of zirconium tetra-<i>n</i>-propoxide in glycols

Development, mechanical and tribological characterization of Al2O3 reinforced ZrO2 ceramic composites

Alumina reinforced zerconia composite materials are attractive structural fabrics, dental and industrial applications that incorporate high hardness and wear resistance, electrical resistance with additional toughness. In this research work Alumina is matrix material and zerconia is reinforced materials. Composites composite material containing different amount of zerconia added to the aluminum oxide i.e. 5%wt, 10%wt and 15%wt and prepared composite materials by using powder metallurgy milling method. The prepared was checked hardness, wear rate, Electrical resistance and Coefficient of linear thermal expansion. Composites are tested for wear intensity with a pin on the disk wear test machine, hardness for the Rockwell hardness tester, electrical resistance for the electrical resistance meter and coefficient of linear thermal linear thermal expansion is for the dilatometer, to analyze the crack propagation of the composite materials after wear by SEM and revealed a fairly uniform distribution of Ultra n-ZrO2 particles with a slight agglomeration. The incorporation of Ultra nano zirconium dioxide particles into aluminum particles lead to produce a aluminum composites with increased mechanical and electrical properties. Aluminum reinforced zirconia Ceramic composites work material are the good surface finish. The surface quality, the dimensional precision has a significant effect and the materials have a useful life.

Preliminary analysis of physical and chemical phenomena occurring in droplet at solution precursor plasma spraying of zirconia coatings

The study describes the physical and chemical phenomena occurring in a droplet at the solution precursor plasma spraying (SPPS) coating deposition. The analysis followed the process stages leading to obtain zirconia coatings from zirconium acetate precursor. The coatings were sprayed and characterized in our previous study. A simple mathematical model was developed to describe the phenomena occurring during the spray process. The results obtained with the model were correlated with the experimental data. The data were obtained by the characterization of the splats obtained at impact of particles on the substrate. In particular, the diameters of zirconia particles before these impacts were calculated from the splats images. The modeling required the knowledge of plasma jet 2-D velocity and temperature fields at the experiments. These data were obtained by using the GENMIX numerical code. Consequently, the heat and momentum transfer between plasma gas and droplets and particles was described and enabled predicting their velocities, trajectories and temperatures in-flight. The model estimates the duration of the chemical phenomena inside droplets and particles in-flight including evaporation of solvents, the homogeneous nucleation and the phases' transformations prior to zirconia particle melting. The simplified model was useful to predict whether the particles were liquid at impact with substrate and helped in optimizing the liquid feedstock injection pressure.