Addition Of ZrO2 Particles Research Articles

Integrated control mechanism of ultrasound and ZrO2 particles on differential microstructures for the wire arc additive manufacturing

ABSTRACT Inhibiting unhomogenised microstructure during the directed energy deposition process with the electric arc energy source (DED-Arc) has become a significant challenge. Ultrasonic vibration leads to the severe stirring of liquid metal and break down dendrites in the inner-layer zone, which promotes the formation of fine grains after rapid solidification. In contrast, the grain refinement effect is not obvious in the semi-melting zone. The addition of ZrO2 particles in the 2319 Al-Cu alloy during the DED-Arc process can drag and pin the grain boundary to prevent grain coarsening in the semi-melting zone. Under the integrated effect of ultrasound and particles, ZrO2 particles can be evenly distributed in different regions, which is beneficial to enhance the microstructure uniformity of the deposition layer and ultimately achieving significant improvement in mechanical properties. The intergrated effect of ultrasonic vibration and particles on strength and elongation reach 13.8% and 92.4%, respectively.

Recycling Aluminium AA6061 Chips with Reinforced Boron Carbide (B4C) and Zirconia (ZrO2) Particles via Hot Extrusion

Compared to the recycling process by remelting, hot extrusion significantly reduces the energy consumption and CO2 emission and ensures good mechanical and microstructural properties. This study investigates the effects of reinforcing aluminium AA6061 chips with mixed boron carbide (B4C) and zirconia (ZrO2) particles by employing a design of experiment (DOE) under 550 °C processing temperature and three hours preheating time. The findings showed that compressive strength (CS) and hardness increased with up to 5% added particles, and beyond 5%, the yielded values decreased because of materials agglomeration. However, the decreasing density was dependent on the addition of ZrO2 particles. The distribution of particles with different volume fractions of mixed particles was investigated by employing SEM, AFM, and EDS tests. Thus, the process can produce a net shape structure that utilises material-bonding consolidation to provide sufficient support to reuse the recovered materials in engineering applications, such as in the automotive industry.

Characterisation of AZ31/ZrO2 composites produced via stir casting

AZ31Magnesium alloy reinforced with different vol% of ZrO2 particle composites have been produced by stir casting process. The effect of ZrO2 vol% on microstructure and mechanical properties of AZ31 alloy has been studied. Significant refinement in grain size was observed in ZrO2 reinforced composites. The hardness, Proof strength and tensile strength of the AZ31/ZrO2 composites increased with increase in addition of ZrO2 particle. However the ductility of the composite sample decreased with the addition of ZrO2 particles. The tensile fractured surface was analyzed using SEM to find the fracture mechanisms.

Fabrication, microstructures and mechanical properties of ZrO 2 dispersion-strengthened Q345 steel

ZrO2 dispersion-strengthened Q345 steel with different ZrO2 contents (0%, 0.5% and 1.2%, mass fraction) was fabricated through combining middle frequency induction furnace melting and cored-wire injection technologies. The microstructure and fracture surface morphology of ZrO2 dispersion-strengthened Q345 steel in casting, normalizing and quenching states were observed using optical microscopy, scanning electron microscopy and transmission electron microscopy. Also, strengthening and fracture mechanisms of the alloys were analyzed. Results showed that the dispersed ZrO2 particles added into Q345 matrix significantly enhanced its strength, and the main strengthening mechanism was the formation of dislocation cells and pinning effect caused by the addition of ZrO2 particles. Apart from that, the hard martensite phase, grain refinement and high ZrO2 particles content also played important roles in strengthening effect. Furthermore, the nanoindentation was also performed to further reveal the strengthening effect and mechanism of dispersed ZrO2 particles in Q345 steel. Results showed that the hardness of ZrO2 dispersion-strengthened Q345 steel increased with the increase of ZrO2 content.

Study on preparation and properties of molybdenum alloys reinforced by nano-sized ZrO2 particles

The nano-sized ZrO2-reinforced Mo alloy was prepared by a hydrothermal method and a subsequent powder metallurgy process. During the hydrothermal process, the nano-sized ZrO2 particles were added into the Mo powder via the hydrothermal synthesis. The grain size of Mo powder decreases obviously with the addition of ZrO2 particles, and the fine-grain sintered structure is obtained correspondingly due to hereditation. In addition to a few of nano-sized ZrO2 particles in grain boundaries or sub-boundaries, most are dispersed in grains. The tensile strength and yield strength have been increased by 32.33 and 53.76 %.

Preparation of Zn-ZrO<sub>2</sub> Nanocomposite Coating by DC and Pulsed Current Electrodeposition Technique with Low Current Density

In the present work, Zn-ZrO2nanocomposite coatings were deposited on the copper substrate through DC and pulse electrodeposition technique with low current density (10 mA/cm2). The effect addition of ZrO2nanoparticles and pulse current were studied. The surface morphology, microhardness and erosion resistance of Zn-ZrO2nanocomposite coating were evaluated. The result shows that, with the addition of ZrO2particles, the surface morphology of Zn-ZrO2nanocomposite coating was smoother. Phase identification by XRD confirm that Zn layer had been sucessfully deposited. The presence of ZrO2nanoparticles was not detected. Compared to DC, pulsed current electrodeposition technique showed higher cathodic efficiency, better microhardness and good erosion resistance.

Effect of ZrO2 particle on the performance of micro-arc oxidation coatings on Ti6Al4V

This paper investigates the effect of ZrO2 particle on the oxidation resistance and wear properties of coatings on a Ti6Al4V alloy generated using the micro-arc oxidation (MAO) technique. Different concentrations micron ZrO2 particles were added in phosphate electrolyte and dispersed by magnetic stirring apparatus. The composition of coating was characterized using X-ray diffraction and energy dispersive spectrum, and the morphology was examined using SEM. The high temperature oxidation resistance of the coating sample at 700°C was investigated. Sliding wear behaviour was tested by a wear tester. The results showed that the coating consisted of ZrTiO4, ZrO2, TiO2. With ZrO2 particle addition, the ceramic coating's forming time reduced by the current dynamic curve. It was shown that the addition of ZrO2 particles (3g/L, 6g/L) expressed an excellent oxidation resistance at 700°C and wear resistance.

Effect of ZrO2 addition on the dry sliding wear behavior of laser clad Ti6Al4V alloy

The relationship between microstructure and wear behavior of Ti6Al4V alloy and three laser-clad composite coatings (TiNi, TiNi5ZrO2, and TiNi10ZrO2) was investigated. Dry sliding wear tests were carried out using a ball-on-disk wear tester under varying loads. WC was used as the counterface material. The results showed that additions of ZrO2 refined the microstructure of TiNi from a dendritic to a flower-like microstructure. An improvement in the microindentation hardness value was also observed. Results indicated that the wear volume of clad TiNi alloy decreased with the addition of ZrO2 particles. The microstructural changes due to ZrO2 additions played a significant role in the wear performance of the clad TiNi alloy. Analysis of worn surfaces and wear debris indicated that the dominant wear mechanism for the Ti6Al4V alloy was adhesive wear with ploughing.

Comparative Evaluation of the Bioactive Behavior of HA and ZrO<sub>2</sub> Reinforced Coatings

The clinical use of plasma-sprayed hydroxyapatite (HA) coatings on metal implants has been widely investigated as the HA coating can achieve the firm and direct biological fixation with the surrounding bone tissue. It is shown in previous studies that the mechanical properties of HA coatings are improved by the addition of ZrO2 particles during the deposition of the coating on the substrate. Subsequently, the cohesive and adhesive strengths of plasma-sprayed hydroxyapatite (HA) coatings were strengthened by the ZrO2 particles addition as a reinforcing agent in the HA coating (HA+ZrO2 composite coating). The aim of the present work is to investigate and evaluate the in vitro bioactivity assessment of HA and HA/ZrO2 coatings, on stainless steel substrate, soaked in c-SBF, in order to study and compare their biological responses. The coatings were produced using vapor plasma spraying (VPS). The characterization of the surface of the coatings before and after soaking in SBF solution was performed using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM) and X-ray Diffraction analysis (XRD). All samples were smoothed before insertion in the medium and the in vitro bioactivity of all coating samples was tested in conventional Simulated Body Fluid (c-SBF) solution for various immersion times.

Dynamic and Static Softening of Sintered MgO-PSZ / TRIP-matrix Composites with up to 10 vol.-% ZrO2

A metal matrix composite (MMC) consisting of AISI 304 austenitic stainless steel with up to 10 vol.-% MgO-PSZ was produced by a powder metallurgic process through sintering at 1300 °C and 1390 °C. The hot working of sintered samples was conducted between 900 °C and 1100 °C. The behaviour of softening kinetics was investigated using flow curve recording methods (dynamic softening) and the double-hit method (static softening). The influence of the deformation parameters such as temperature, strain rate, inter-pass time and relative density of the samples was determined. The microstructure development of the sintered composite after hot forming was determined by optical microscopy and SEM and was interpreted with the help of qualitative microstructure analysis. The results show a general acceleration of softening processes with increasing temperature and strain rate, with the addition of ZrO2 particles and a decrease in the density of composite materials. A mathematical-physical model was developed to predict the softening behaviour and optimize the forming processes of the composite in the light of these results.

Interfacial modification and impact properties of Nb/MoSi2 laminate composites by the addition of ZrO2, NbSi2, and SiC particles

In this study, the results of a thermodynamical estimation indicate that the impact properties of Nb/MoSi2 laminate composites can be improved by suppressing the interfacial reaction. The effects of addition of SiC, NbSi2, and ZrO2 on the impact properties and interfacial reaction of Nb/MoSi2 laminate composites are also examined. Laminate composites, which comprise alternate layers of matrix mixture and Nb foil, were fabricated by the hot press process. Addition of ZrO2 particle is clearly demonstrated to increase both the impact value and the sintered density of Nb/MoSi2 laminate composites. The thickness of the interfacial reaction layer in Nb/MoSi2 laminate composites dramatically decreases with increasing volume fraction of ZrO2 particle. The suppression of the interfacial reaction is caused by the formation of ZrSiO4 in the MoSi2-ZrO2 matrix mixture. In addition, it appears that the reduction of the reaction layer promotes the plastic deformation of Nb foil and the interfacial delamination in laminate composites.

Interfacial microstructures and impact properties for Nb/MOSi2 laminate composites

The purpose of present work is to investigate effects of fabricating temperature and ZrO2, SiC and NbSi2 addition on interfacial reaction layer and impact properties for Nb/MoSi2 laminate composites. Four types of laminate composites alternating four layers of Nb foil with each MoSi2, mixture layer containing ZrO2. SiC and NbSi2 particles were fabricated by hot pressing. The volume fraction of Nb foil involved in these system was nominally 10 vol%. It has been found that the impact value of Nb/MoSi2 laminate composites decreased at a fabricating temperature higher than 1523 K, since the thickness of reaction layer between Nb and MoSi2 increased along with fabricating temperature. However, the addition ofZrO2 particles to Nb/MoSi2 laminate composites fabricated at 1623 K resulted in a change of the interfacial microstructure as well as a reduction of the reaction layer. Nb/MoSi2-ZrO2 laminate composites maintained the same density as that of Nb/MoSi2 laminate composites fabricated at 1773 K and showed a higher impact value than that of Nb/MoSi2 laminate composites at 1523 K.

Toughening Behavior Involving Multiple Mechanisms: Whisker Reinforcement and Zirconia Toughening

Since the contribution of transformation toughening increases with the loca crack resistance (which is proportional to the toughness of the matrix), ZrO2 particles were added to a toughened, whisker‐reinforced ceramic matrix. Analysis revealed that the combination of these multiple toughening agents should result in ceramic composites tougher than (1) that achieved by either mechanism by itself or (2) the sum of the two processes. The toughness of mullite could be increased 1.8‐and 2.4‐fold with a 20 vol% addition of ZrO2 particles or SiC whiskers, respectively. However, when 20 vol% of both ZrO2 particles and SiC whiskers were added, the toughness was increased at least 3‐fold with monoclinic m‐ZrO2 and by >5‐fold with tetragonal t‐ZrO2. The differences in the toughening achieved when t‐ZrO2 vs m‐ZrO2 is present in the SiC‐whisker‐reinforced mullite are attributed to differences in their interdependencies upon the whisker reinforcement.