ZrB2 Particles Research Articles

Microstructure and properties of 6111Al matrix composites reinforced by the cooperation of in situ ZrB2 particles and Y

In this research work, the new kind of 6111Al matrix composites reinforced by nanosized ZrB2 particles and rare earth element Y have been successfully prepared via the Al-KBF4-K2ZrF6-Y in situ reaction system in the melt. Compared to the traditional particle reinforced aluminum matrix composite, this innovative fabrication system broke through the limit in the content of reinforcing phases and helped to modify the morphology and distribution of in situ ZrB2 particles with assistance of Y addition. The results of tensile testing on 6111Al-3 wt%ZrB2-0.3 wt%Y composites revealed that the YS, UTS and elongation reached to 295 MPa, 325 MPa and 13.2%, which have been increased by 28.2%, 19.5% and 83.3% respectively compared to the matrix alloy. The distribution state and morphology of reinforcing phases including in situ ZrB2 particles, Al3Y and Y5Si3 precipitates were analyzed by the latest equipments like X-ray diffraction (XRD), Optical microscope (OM), Scanning electron microscope (SEM) and High resolution transmission electron microscope (HRTEM) equipped with Energy dispersive spectroscope (EDS).

Microstructure and Wear Behavior of Squeezed Magnesium Alloy (AM100) Based Composites Reinforced with ZrB<sub>2</sub>, Graphite and Hybrid of ZrB<sub>2</sub> and Graphite Particles

An attempt has been made to investigate the microstructures and wear behavior of magnesium alloy AM100 (Mg-Al-Mn) based composites reinforced with 7 vol. % of ZrB2, graphite or hybrid of (1:1) ZrB2 and graphite particles as well as the unreinforced magnesium alloy. Magnesium alloy was melt under shield of inert gases and composites were prepared using stir casting method. Optical microscopy was used to study the microstructures of the unreinforced alloy and composites. The composites characterized primarily by the uniform distribution of particles in the matrix and a good adherence between the particles and matrix. XRD analysis was used to identify the phases of the unreinforced alloy and composites. The XRD diffraction pattern of AM100 matrix reveals different phases, namely, Mg, AlMn and Al12Mg17. Formation of these phases is due to the reaction between alloy constituents. Dry sliding wear tests were conducted by using a pin-on-ring apparatus. The wear rates of the composites and matrix alloy were measured at loads of 10, 20 and 30 N, and sliding speed of 0.7 m/s. The worn surfaces of the composite pins were examined by scanning electron microscopy (SEM). The experimental results of the wear tests showed that the magnesium based composites exhibited higher wear rate at all the applied loads when compared to those of the unreinforced magnesium alloy. The ZrB2 reinforced magnesium composite exhibited the lowest wear rate amongst the composites material investigated in the present work.

Effects of particulate agglomerated degree on deformation behaviors and mechanical properties of in-situ ZrB2 nanoparticles reinforced AA6016 matrix composites by finite element modeling

In this paper, both the tensile deformation behaviors and mechanical properties of in situ ZrB2 nanoparticles reinforced AA6016 matrix composites are investigated with finite element analysis. For the modeling, the volume fraction of nano ZrB2 particles is defined by combining cluster sizes with particulate agglomerated degree which was observed in the agglomeration clustered regions by experiments. The effects of clusters on the mechanical behaviors of composites are disclosed according to qualify mechanical behaviors of local particulate agglomeration. The results indicate that finite element analysis is performed to predict the Young’s modulus of composites, which is in good agreement with the experimental results. In addition, the speed of stress concentration is faster when the agglomerated degree elevates, which minimizes elongation of composites under the same particle volume fraction. Likewise, under the same agglomerated degree, the higher particle volume fraction of composites triggers the reduction of elongation.

Design of an in–situ multi–scale particles reinforced (Al2O3+ZrB2+AlN)/Al composite with high strength, elasticity modulus and thermal stability

The thought of designing Al–based composites with attractive comprehensive properties, by using various particles as reinforcements simultaneously, has been put forward and verified in this paper. By in–situ synthesizing Al2O3 (<1 μm), ZrB2 (<300 nm) and AlN (<100 nm) particles, a novel (Al2O3+ZrB2+AlN)/Al composite has been prepared. It was found that the ultimate tensile strength of the composite is as high as 540 MPa at 25 °C and 200 MPa at 350 °C, while the elasticity modulus of the composite is 101 GPa. Besides, the composite also performs attractive thermal stability and the coefficient of thermal expansion is 15.8×10–6 K–1 at 500 °C. It is regarded that the synergistic effect of the multi–scale Al2O3, ZrB2 and AlN particles are responsible for the improved performance. This paper may be referred for designing multiphase reinforced composites to achieve various properties.

Abrasive Wear Study of AA7075/ZrB2 Reinforced Composites

AA7075-xZrB2 (x = 0, 5, 10, 15, and 20 wt.%) composites were manufactured by reacting potassium zirconium fluoride (K2ZrF6) and potassium tetrafluoroborate (KBF4) with molten AA7075 at 800°C. The ZrB2 particles formed by the reaction were fairly uniformly distributed throughout the whole composite. The microhardness of the composites increased from 45 to 78 VHN with ZrB2 contents from 0 to 20 wt.%, respectively. The wear rate rose as the load and sliding distance increased and fell as the sliding speed increased. The material-removal mechanism of the composites was due to abrasive wear.

Effect of Machining Parameters on Cutting Force and Surface Roughness during Dry Turning of Al6061/Zrb2alumium Matrix Composite

This paper shows that the outcome of analysis by the machining of Al-6061–ZrB2.which has done through in-situ reactions. Al 6061 alloy is reinforced with zirconium diboride by stir casting method.The reaction of K2ZrF6 and KBF4 will form ZrB2 at a temperature of 860°C and a holding time of 45 minutes using in-situ reaction. The molten metal matrix composite is poured into the pre-heated die with diameter of 50mm and length 500 mm. Influence of reinforcement ratio of 0, 5 and 10 wt% of ZrB2 on machinability are examined. By the turning operation cutting force was reduced, when the cutting speed has increased. The increment in ZrB2 particles within the matrix decreases the cutting force. Surface roughness is enhanced due to improvement in surface roughness and cutting speed deteriorated because of more addition of reinforcement.

SiC whiskers: A strategy to modify the high-temperature performance of laminated ZrB2–SiC ceramics

With SiC whisker and SiC particle as interface layers, ZrB2–SiC–SiCw (LZ-Sw) and ZrB2–SiC–SiCp (LZ-Sp) laminated ceramics were prepared by tape casting and hot pressing. Fracture behaviors and accompanying microstructural changes were studied in the range from 20 to 1500 °C. At 20 °C, both LZ-Sw and LZ-Sp exhibited excellent flexural strengths in parallel direction of 607 ± 58 and 568 ± 46 MPa, respectively. From 20 to 1500 °C, the flexural strength of LZ-Sw was always higher than that of LZ-Sp. From 1200 to 1500 °C, the flexural strength of LZ-Sw declined relatively slowly while that of LZ-Sp dropped sharply. At 1500 °C, the flexural strength of LZ-Sw reached 361 MPa in the parallel direction, 66.4% higher than that of LZ-Sp (217 MPa). The superior high-temperature performance of LZ-Sw was caused by porous interface layers composed of SiC whiskers and ZrB2 particles, which reduced the enrichment of the glassy phase and avoided grain-boundary sliding.

Characterization of in Situ Zirconium Diboride (Zrb2) Reinforced by Aluminium-Copper (Al-Cu) Metal Matrix Composites

Aluminium matrix composites by way of in-situ reaction has arisen as a preference conducive to knock out imperfections and defects exiting within ex situ MMC. In the present work, Al-Cu-ZrB2 have been develop through in situ reaction which boost mechanical properties over dispersion strengthening together with grain refinement obtained by the existence of each particulates inside the melt all along solidification. Al-Cu reinforced among different proportion of ZrB2 (0, 3 and 6 wt. %) synthesized using in situ fabrication at 800 °C of molten aluminum-copper alloys by inorganic salts K2ZrF6 together with KBF4. The amalgam were specified using XRD, FESEM together with mechanical test on appropriately sectioned and metallographically prepared surface to examine and inspect phase distribution, hardness together with tensile properties. From result acquired, raised ZrB2 amount will increase rate of tensile and hardness characteristics of Al-Cu alloy. XRD patterns exposed development of ZrB2 particulates without existence of unspecified other compounds. Most of ZrB2 granular were located near grain boundaries of Al dendrites. Microstructural analysis exposed the homogeneous and consistent allocation of second phase particles, clean interface and favorable bonding. It is support that ZrB2 molecules are predominantly in nano size among hexagonal either tetragonal shape, yet minor molecules in micron size are also noticed. For that reason, composite synthesized using in situ techniques exhibit homogeneous distribution of reinforcing tend to be superlative associated within clean interface along the metallic matrix. In order to accomplish better mechanical features, it is necessary to regulate and control phase arrangement all along fabrication of Al-Cu with higher contents of ZrB2.

Erosion mechanism of ternary-phase SiC/ZrB2-MoSi2-SiC ultra-high temperature multilayer coating under supersonic flame at 90° angle with speed of 1400 m/s (Mach 4)

A ternary-phase SiC/ZrB2-MoSi2-SiC multilayer coating was prepared on graphite by two-step reactive melt infiltration (RMI) method. The formation mechanism of the coating was studied by HSC chemistry software 6.0. The erosion resistance of the coating was investigated by supersonic flame erosion test at 90° angle, temperature of 2173 K and speed of 1400 m/s (Mach 4) for 120 s. Erosion test results revealed that the SiC/ZrB2-MoSi2-SiC multilayer coating had very good erosion resistance. Weight change percentage, mass erosion rate and linear erosion rate of the coating were −0.18 %, −0.027 × 10−3g cm−2 s−1 and 0.33 μm s−1, respectively. Microstructural characterization demonstrated that interesting structures such as rod-like, flake-like, spherical, worm-like and fibrous structures were formed during erosion test. The erosion mechanism of ZrB2-MoSi2-SiC coatings is controlled both chemically and mechanically. The reduction of chemical degradation can be attributed to the presence of MoSi2 particles and the reduction of mechanical degradation can be related to the presence of ZrB2 particles.

Hybrid aluminum matrix composites containing carbon nanotubes and zirconium diboride particles: fractography, microstructure and mechanical performance

Hybrid aluminum matrix composites (HAMCs) containing carbon nanotubes (CNTs) and zirconium diboride (ZrB2) particles were prepared via solid-state powder metallurgy route. The constituents of HAMCs were initially ball milled for uniform dispersion, and subsequently composite mixtures were consolidated by cold compaction, which was followed by pressureless sintering. The fractions of nanotubes and ceramic particles in HAMCs were 0.5 wt% and 5.0 wt%, respectively. Individually reinforced composites containing 0.5 wt% MWCNTs and 5.0 wt% ZrB2 particles were also prepared for reference together with pure aluminum. X-ray diffraction identified the crystalline phases while optical and scanning electron microscopy revealed uniform dispersion of reinforcements without their agglomeration. Mechanical characterization showed a significant rise in the properties of HAMCs over unreinforced aluminum and composites containing individual reinforcements. The improvements of ~ 26%, ~ 34% and ~ 19% in hardness, compressive strength and flexural strength were observed in comparison with pure aluminum, respectively. The examination of fractured surfaces revealed the strengthening mechanisms responsible for the improvement in mechanical performance of HAMCs.

Fabrication of stircast ZA/ZrB2 reinforced in-situ composites

This work outlines the preparation of Zinc-Aluminium (ZA)/ZrB2 composite via in situ stir casting technique. X-ray diffractometer (XRD) has been used for phase identification, optical microscopy (OM) for microstructural analysis and scanning electron microscopy (SEM) for in-depth analysis of microstructure. Four compositions with 0, 3, 6 and 9 vol% ZrB2 were prepared. XRD analysis confirms the formation of ZrB2 particles. It also shows peaks of zinc and aluminium. Absence of any other peak confirms that reaction was completed. Optical micrographs show that generation of second phase particles has refined the grains of matrix phase. Hexagonal and rectangular morphology of particles is clearly observed while studying under SEM. Evaluation of mechanical properties shows that with increase in ZrB2 vol% the tensile strength as well as compressive strength increases at the expense of ductility. Also remarkable increase in hardness is measured with increase in ZrB2 vol%.

Effect of ZrB2 content on the densification, microstructure, and mechanical properties of ZrC-SiC ceramics

ZrC ceramics containing 30 vol% SiC-ZrB2 were produced by high-energy ball milling and reactive hot pressing. The effects of ZrB2 content on the densification, microstructure, and mechanical properties of ceramics were investigated. Fully dense ceramics were achieved as ZrB2 content increased to 10 and 15 vol%. The addition of ZrB2 suppressed grain growth and promoted dispersion of the SiC particles, resulting in fine and homogeneous microstructures. Vickers hardness increased from 23.0 ± 0.5 GPa to 23.9 ± 0.5 GPa and Young’s modulus increased from 430 ± 3 GPa to 455 ± 3 GPa as ZrB2 content increased from 0 to 15 vol%. The increases were attributed to a combination of the higher relative density of ceramics with higher ZrB2 content and the higher Young’s modulus and hardness of ZrB2 compared to ZrC. Indentation fracture toughness increased from 2.6 ± 0.2 MPa⋅m1/2 to 3.3 ± 0.1 MPa⋅m1/2 as ZrB2 content increased from 0 to 15 vol% due to the increase in crack deflection by the uniformly dispersed SiC particles. Compared to binary ZrC-SiC ceramics, ternary ZrC-SiC-ZrB2 ceramics with finer microstructure and higher relative densities were achieved by the addition of ZrB2 particles.

ZrB2 nanoparticles transmuting tribological properties of Al3Zr/AA5052 composite

Good work hardenability, moderate to high strength of AA5052 alloy and high melting point and elastic modulus of Al3Zr with limited wear resistance have been the driving force to transmute Al3Zr/AA5052 composite by generations of ZrB2 nanoparticles. For this purpose, the varying amounts of ZrB2 particles in Al3Zr/AA5052 composite have been produced by direct melt reaction in situ technique. The phase identification, microstructural studies and wear testing have been performed for all the composites. The phase identification and microstructural studies indicate that the ZrB2 particles are formed successfully in the Al3Zr/AA5052Al composite with hexagonal and rectangular morphology within a size range of 10–190 nm. Wear testing results show that friction coefficient (COF) fluctuates with sliding distance, whereas it decreases with normal load. For the composite without ZrB2, the COF is exhibited increasing trend with sliding velocity, while for the hybrid composites initially it decreases, but beyond 2 m/s sliding velocities it starts increasing. Wear studies also show that with ZrB2 generation in Al3Zr/AA5052 composites can be used up to larger loads and higher sliding velocities while being in mild wear regime. It is observed that the mild wear regime extends and COF increases with the increase in vol% of ZrB2 particles. Texture analysis of worn surfaces is in agreement with the results. The present investigation shows that in situ (ZrB2 + Al3Zr)/AA5052 hybrid composites could be a promising material in the applications requiring high wear resistance and high COF such as braking system.

Experimental investigation and characterization of in situ synthesized sub micron ZrB2-ZrC particles reinforced hybrid AA6061 aluminium composite

In the present work, AA6061 aluminum matrix composite (AMCs) was fabricated by mixing AA6061 matrix with the byproducts of in situ reaction namely ZrB2 and ZrC sub micron particles. The in situ reaction took place between K2ZrF6, KBF4 and SiC particles. The Fabrication of AMCs was done under a controlled environment using an electric stir casting furnace. The mechanical and microstructural properties of as cast AMCs were investigated by Differential thermal analysis (DTA), x-ray diffraction patterns (XRD), Field emission scanning electron microscope (FESEM), Electron back-scattered diagram (EBSD), and transmission electron microscopy (TEM). The in situ formation of ZrB2 particles in AA6061 aluminum matrix occurred at a temperature of 852.8 °C and ZrC particles at 1116.8 °C, which was confirmed by Heat flow curves obtained by differential thermal analysis (DTA). The formation of ZrB2 and ZrC particulates in the AMCs is also ascertained by XRD and FESEM results. The homogeneous distribution of in situ formed ZrB2 and ZrC particles in the AMCs with good interfacial bonding was confirmed from the FESEM micrographs. The refinement of grains of aluminum matrix by the in situ formed ZrB2 and ZrC particles was proved by EBSD maps. The in situ formed ZrB2 and ZrC particles in the AMCs exhibited hexagonal and spherical shapes, thermodynamically stable structure, increased the microhardness and UTS of in situ fabricated AMCs.

Role of zirconium diboride particles on microstructure and wear behaviour of AA7075 in situ aluminium matrix composites at elevated temperature

ABSTRACTThe present research work examines the impact of temperature on the dry sliding wear behaviour of AA7075 aluminium strengthened zirconium diboride (ZrB2) particulate composite (0, 3, 6, 9 and 12 wt.%). The dry sliding wear behaviour of the AMCs was inspected utilizing a pin-on-disc machine at differing temperatures (40, 60, 120, 180 and 240°C). The wear resistance of AMCs improved with the increased substance of ZrB2 particulates at all test temperatures. The worn surface of the AMC pins was described utilizing FESEM. It was found from the SEM micrographs of worn surface, that at different temperatures, adhesion and metal flow were the prime wear process of the AA7075 composites, while for in situ formed AMCs, metal stream and oxidation were the factors affecting the wear process. The worn surface of the AMCs showed that there was a modification in wear component from abrasive wear to metal flow.

Synergistic reinforcement of in situ (ZrB2+TiB2) particles and Er on microstructure and properties of 6082Al matrix composites

In present work, the effects of in situ (ZrB2+TiB2) particles and rare earth element Er on microstructure and mechanical properties of 6082Al matrix composites were investigated respectively. On the basis of research above, the characteristics of synergistic enhancement of them can be analyzed. The results indicated that the mechanical properties of 6082Al-3wt%(TiB2+ZrB2)-0.5 wt%Er composites reached to the maximum values with YS, UTS and elongation were 285 MPa, 330 MPa and 11.7% respectively, which increased by 13.1%, 13.8% and 85.8% respectively compared with the 6082Al matrix alloy. The addition of Er to the 6082Al-(TiB2+ZrB2) composites contributed to the notable modification on distribution and morphology of in situ particles that the large particle clusters almost disappeared and the size of TiB2 and ZrB2 particles decreased a lot compared with the situation without Er addition. The grain size of the matrix alloy decreased from 115.4 μm to 43.8 μm when the Er addition is 0.5 wt%. The Er-containing precipitates and in situ TiB2 and ZrB2 particles were confirmed by Optical microscope, Scanning electron microscopy, Transmission electron microscopy, Energy dispersive spectroscopy, and X-ray diffraction.

Effects of rolling on microstructures and properties of in-situ (TiB2 + ZrB2)/AlSi9Cu1 composites

In this paper, the (TiB2 + ZrB2)/AlSi9Cu1 composites were fabricated via in situ reaction from Al-K2TiF6-K2ZrF6-KBF4 reaction system. The effects of rolling on microstructures and properties of the composites were investigated by XRD, SEM, TEM and mechanical tensile test. In addition, the influence mechanisms of plastic deformation on aluminum alloy composites were discussed in detail. The results show that the in situ TiB2 and ZrB2 particle well distributed in the matrix with the size of 20∼50 nm and the morphology is short-stick or plate. The rolling technology could obviously optimize the microstructure, enhance the properties of the composite especially, after 6 passes hot rolling and 4 passes cold rolling, the TiB2 and ZrB2 particles clusters with size range from 80 to 150 nm were uniformly distributed in the matrix, the Si phases were fractured into different small parts with the size of less than 1 μm and the grains size were further reduced. The ultimate tensile strength (UTS) and elongation (EL) of in situ composite are 282 MPa, 17.6%, respectively. Also, the Portevin-Le Chatelier (PLC) phenomenon found in the composite was discussed.

Tribological and mechanical properties of Zirconium Di-boride (ZrB2) particles reinforced aluminium matrix composites

In the last few decades, the interest of using the metal matrix composites (MMCs) has enhanced owing to its potential for replacing the traditional materials in several industrial applications. In this articles, a state of the art review on Zirconium Di-boride (ZrB2) particles reinforcement aluminium matrix composites. This review paper exhibits the mechanical and tribological properties of ZrB2 particles reinforced aluminium matrix composites. Mostly the ZrB2 particles based composites are prepared by in situ casting technique and the very few research works are done in other processing technique. Generally the properties of the composites are increased with the increase in ZrB2 particle content.

Microstructure evolution of MeB2 (Me=Zr, Ti) powders prepared by borothermal reduction during heat treatment at 1000°C–1800°C

Microstructure evolution of MeB2 (Me = Zr, Ti) powders prepared by borothermal reduction of the corresponding oxides with boron under vacuum was investigated after heat-treatment at different temperature. The existence of the by-product B2O3 resulted in the coarsening of faceted ZrB2 particles at 1550 °C or below, whereas B2O3 showed almost no effect on the size and morphology of TiB2 or Zr0·98Ti0·02B2 particles. It could be concluded that the coarsening of ZrB2 in the temperature range of 1000 °C–1550 °C was caused by the dissolution-reprecipitation mechanism. While, few effects on TiB2 or Zr0·98Ti0·02B2 was found in this temperature range. When subject to higher temperature in B2O3-free environment, the growth was inversely evidenced on TiB2 and Zr0·98Ti0·02B2 but the growth of ZrB2 particle could be retained, indicative of the surface diffusion, which controlled the particle growth at high temperature.

The microstructures and properties of in-situ ZrB2 reinforced Cu matrix composites

In this work, ZrB2 particles have been in-situ synthesized in the Cu melts using Cu-B master alloy as the starting material. It is found that the non-uniformly distributed ZrB2 particles in the prepared as-cast composites tend to aggregate into agglomerations and this trend is more pronounced with the ZrB2 content increasing.In addition, the size of hexagonal plate-like ZrB2 whose diameter ranges from less than 1 μm to more than 10 μm accompanied by the thickness ranging from about 0.5 μm to 2 μm shows an uneven appearance. The increasing ZrB2 contents can give rise to the higher hardness values of 160–205% of the original pure Cu. However, the electrical conductivity which is about 52.9% IACS to 76.8% IACS will be severely affected. Besides, the decreased friction coefficient from 0.6 to 0.4 and the gradually declining lost mass of the samples indicates the better wear resistance property with increasing ZrB2 contents.