Alumina Filler Research Articles

Ultralow wear PTFE composites filled with beryllia and germania particles

Nanosized α-phase alumina has been one of the few inorganic fillers that could induce 10−7 mm3/Nm ultralow wear rates of PTFE for the past two decades. We report here two additional oxide fillers, beryllia (BeO) and germania (GeO2) particles, that exhibit comparable wear reduction ability when filled in PTFE. Particle size and surface chemistry analysis revealed that the beryllia and germania particles had different structure and size from the alumina fillers used in this study whereas their composites shared similar ultralow wear rates and carboxylate salt rich tribofilms to the alumina PTFE system. Results in this study support both a particle structure driven and a tribochemistry driven wear reduction hypothesis for the alumina PTFE composite as previously suggested; whereas more systematic investigations are needed to elucidate wear resistance mechanisms in the beryllia and germania filled PTFE composites.

Mechanical, Thermal and Rheological Properties of Polyethylene-Based Composites Filled with Micrometric Aluminum Powder.

Investigations related to polymer/metal composites are often limited to the analysis of the electrical and thermal conductivity of the materials. The presented study aims to analyze the impact of aluminum (Al) filler content (from 1 to 20 wt%) on the rarely investigated properties of composites based on the high-density polyethylene (HDPE) matrix. The crystalline structure, rheological (melt flow index and oscillatory rheometry), thermal (differential scanning calorimetry), as well as static (tensile tests, hardness, rebound resilience) and dynamic (dynamical mechanical analysis) mechanical properties of composites were investigated. The incorporation of 1 and 2 wt% of aluminum filler resulted in small enhancements of mechanical properties, while loadings of 5 and 10 wt% provided materials with a similar performance to neat HDPE. Such results were supported by the lack of disturbances in the rheological behavior of composites. The presented results indicate that a significant content of aluminum filler may be introduced into the HDPE matrix without additional pre-treatment and does not cause the deterioration of composites’ performance, which should be considered beneficial when engineering PE/metal composites.

Finite element modelling of the filler wire feeding in the hybrid metal extrusion & bonding (HYB) process

HYB is a new solid-state joining method for metals and alloys that utilises continuous extrusion as a technique to enable aluminium filler metal additions. In the present paper a finite element (FE) model for the filler wire feeding inside the HYB PinPoint extruder has been developed and implemented within the commercial software package Deform 3D ™. Based on a comparison with experimental data for the extruder housing temperature, the drive spindle torque and the wire feed rate, it is concluded that the FE model is sufficiently relevant and comprehensive to be used in future developments of the HYB process. In addition to improved wire feeding control, a model-based approach will make it possible to reduce the engineering time and costs involved in case a modification of the design is needed to optimise the extruder performance in a real joining situation.

Mechanical and microwave absorption properties of SiCf/SiC–Al4C3 composite with EPD-SiO2/ZrO2 interphase prepared by precursor infiltration and active filler-controlled pyrolysis method

The SiO2/ZrO2 interphase was successfully prepared on SiC fibers by electrophoretic deposition (EPD) method and SiCf/SiC–Al4C3 composites were fabricated by precursor infiltration and active filler-controlled pyrolysis process using mixed PCS and aluminum fillers as precursors. The morphology of EPD-SiO2/ZrO2 interphase was observed by scanning electron microscopy (SEM) and its microstructure was characterized. The results indicated that a dense and smooth SiO2/ZrO2 interphase can be obtained by EPD method. The effects of EPD-SiO2/ZrO2 interphase on the mechanical, dielectric and microwave absorption properties of SiCf/SiC–Al4C3 composites were investigated. The flexural strength and fail displacement of SiCf/SiC–Al4C3 composite with 330 nm thick EPD-SiO2/ZrO2 interphase have been dramatically improved to 360 MPa and 0.58 mm, respectively, which were four times more than those of SiCf/SiC–Al4C3 composite without interphase. In addition, the complex permittivity of SiCf/SiC–Al4C3 composites were improved slightly from 6.8-3.5j to 8.5-3.9j at 10 GHz with the introduction of EPD-SiO2/ZrO2 interphase attributed to the inhibition of reaction between aluminum fillers and SiC fibers. Moreover, the introduction of EPD-SiO2/ZrO2 interphase has little influence on the microwave absorption properties of SiCf/SiC–Al4C3 composites and the effective microwave absorption band (RL ≤ −10dB) of SiCf/SiC–Al4C3 composites with EPD-SiO2/ZrO2 interphase reached to 3.9 GHz in X band according to the calculation values of reflection loss (RL), indicating its promising application in the field of structural and microwave absorption.

Characterization of Fresh and Cured Properties of Polymer Concretes Based on Two Metallurgical Wastes

Polyester polymer concretes can substitute conventional concretes based on their usually good mechanical strength, adequate physical properties, and high resistance against aggressive chemical environments. They also show a high potential for using recycled targets in their manufacturing. This paper analyzes the fresh and cured properties of polyester polymer concretes containing two metallurgical wastes, namely: ladle slag and alumina filler. Both targets require a higher resin dosage than sand. The standard consistency test showed a low representativeness of the recycled fresh mixes’ workability. The ladle slag and alumina filler samples showed a higher length plastic shrinkage than those containing sand. All of the targets obtained cured density values in the range of 1.589–1.912 g/cm3. From a mechanical point of view, the sand and alumina filler containing polyester polymer concretes reached 11.02 and 10.93 kN, respectively, of flexural strength, while the ladle slag samples showed the best result with 19.31 kN. In the compressive strength test, the sand and alumina filler combinations reached 106.16 and 104.21 MPa, respectively, while the ladle slag achieved 160.48 MPa. The flexural and compressive elasticity modulus showed similar trends related to the resin content.

Durability of polyester polymer concretes based on metallurgical wastes for the manufacture of construction and building products

Varied target materials can be incorporated into polyester polymer concretes (PPC). This allows natural aggregates to be substituted for different waste products in non-structural polymeric construction and building materials. Many studies have explored the mechanical properties of waste-based PPC, but the durability and surface resistance of these materials is not fully known. In this study, we compared the suitability of two metallurgical wastes to that of two natural aggregates for manufacturing durable PPC products. Durability against environmental conditions, durability against chemical products, and surface strength against physical damage were tested. Durability against environmental conditions was characterised according to visual damage and mechanical strength losses after freezing-thawing; no PPC combinations exhibited surface damage following the ageing cycles. The ladle slag (LS) samples exhibited the best pre- and post-test flexural and compressive strength. The properties of the alumina filler (AF) combinations exhibited the highest flexural and compressive strength losses after freezing-thawing. The calcareous sand combinations were damaged most severely by acid, while LS and AF exhibited good resistance against chemical substances. The LS combinations exhibited the highest surface strength against impacts in the rebound number test, while the results obtained for the AF combinations were close to those of natural aggregates. The surface resistance against scratching depended on the resin, not on the target material.

Investigation on slurry erosion of Al<SUB align="right">2O<SUB align="right">3 incorporated glass/epoxy composites

The jet erosion of fibre reinforced plastics (FRPs) has been reported in many literatures available, but very few have reported on their slurry erosion behaviour of FRPs. Furthermore, limited studies have paid attention on slurry erosion characterisation of filler incorporated FRPs. Hence, present study was focused on slurry erosion behaviour of alumina fillers incorporated glass/epoxy composites. The parameters considered were slurry concentration, contact angle and impact velocity. The experimental results reveal that increase in filler percentage increased the erosion resistance of glass/epoxy composites. The increase in slurry concentration and impact velocity has resulted in higher amount of erosion of studied composites. The material loss due to erosion increased with increase of impact angle till 45°, whereas further increase in impact angle caused reduction in wear. Erosion mechanisms were studied through SEM image of eroded samples. Worn surface analysis revealed that plastic deformation, matrix debonding with microcutting, microploughing, and pulverisation were dominant erosion mechanisms at 45° to 60° impact angle.

Investigation on slurry erosion of Al<SUB align="right">2O<SUB align="right">3 incorporated glass/epoxy composites

The jet erosion of fibre reinforced plastics (FRPs) has been reported in many literatures available, but very few have reported on their slurry erosion behaviour of FRPs. Furthermore, limited studies have paid attention on slurry erosion characterisation of filler incorporated FRPs. Hence, present study was focused on slurry erosion behaviour of alumina fillers incorporated glass/epoxy composites. The parameters considered were slurry concentration, contact angle and impact velocity. The experimental results reveal that increase in filler percentage increased the erosion resistance of glass/epoxy composites. The increase in slurry concentration and impact velocity has resulted in higher amount of erosion of studied composites. The material loss due to erosion increased with increase of impact angle till 45°, whereas further increase in impact angle caused reduction in wear. Erosion mechanisms were studied through SEM image of eroded samples. Worn surface analysis revealed that plastic deformation, matrix debonding with microcutting, microploughing, and pulverisation were dominant erosion mechanisms at 45° to 60° impact angle.

A First Approach on Modelling the Thermal and Microstructure Fields During Aluminium Butt Welding Using the HYB PinPoint Extruder

Hybrid metal extrusion & bonding (HYB) is a new solid-state joining method for metals and alloys that utilizes continuous extrusion as a technique to enable aluminium filler metal additions. In the HYB case, heat is generated by friction between the rotating tool and the workpiece and by plastic deformation of the base and filler materials. To get further insight into how the PinPoint extruder behaves during aluminium butt welding, a finite element (FE) model for the HYB process has been developed by exploiting the framework provided by the numerical code WELDSIM. The model allows the thermal and microstructure fields along with the resulting HAZ hardness profile to be calculated from knowledge of the net power input. In the present investigation the FE model is used to determine the energy efficiency of the HYB process following calibration against thermal data being obtained from dedicated in-situ thermocouple measurements. In the future the FE element model will be extended to enable predictions of both residual stresses and global distortions by taking full advantage of the opportunities that the numerical code WELDSIM offers.

Simulating the dependence of the filler wire feeding on the wire size in the hybrid metal extrusion & bonding (HYB) process

HYB is a new solid-state joining method for metals and alloys that utilizes continuous extrusion as a technique to enable aluminium filler metal (FM) additions. In the present work, a finite element (FE) model for the filler wire feeding inside the HYB PinPoint extruder has been developed and implemented within the commercial software package DEFORM 3DTM. Adaptive remeshing is used to handle the high mesh distortions occurring during simulation. Moreover, modelling of the FM flow stress as a function of strain, strain rate and temperature is done by employing a modified version of the Johnson-Cook constitutive equation and experimental tensile test data for the AA6082 filler wire. In the numerical simulations, the feeding behaviour of filler wires with diameters of 1.2, 1.4 and 1.6 mm, respectively has been explored. The results show that the filler wire feeding is sensitive to variations in the extrusion chamber geometry. For the specific combinations of wire diameters and extrusion chamber geometries examined, the ɸ1.4 mm wire appears to be the best choice when it comes to reducing feeding problems related to buckling & breaking of the filler wire during extrusion & joining.

Tensile Behavior of PLA and PLA Composite Materials Under Different Printing Parameters

Polylactic acid (PLA) is one of the most extensively used biodegradable aliphatic polyester produced from renewable resources, such as corn starch. Due to its qualities, PLA is a leading biomaterial for numerous applications in medicine as well as in industry, replacing conventional petrochemical - based polymers. The purpose of this paper is to highlight the mechanical properties, such as tensile stress, of pure PLA specimens in comparison with PLA based-composites, with three different added materials in PLA mass: Copper, Aluminum and Graphene, as well as the influence of filament angle deposition on these properties. In order to check if the the filling density of the specimen influences the ultimate tensile stress (UTS), three different filling percentages (60%, 80% and 100%) have been chosen in the experimental tests. In this context, the mechanical characteristics of four different filament types based on PLA material, starting from pure PLA to PLA with Aluminum, Copper or Graphene filler are compared. Understanding and controlling these parameters is essential for the successful use of PLA and PLA-based composites in different areas such as medical applications, sport equipments and light industry.These tests have been performed due to the fact there is a lack of information concerning the mechanical properties. In the scientific literature, such information is only available for expensive printing systems; for open source printers (as those used in these tests), the information is poor and for some new materials, even inexistant. According to the technical specifications, for an expensive printer the cost may exceed 3000 Euros, with a minimum layer resolution of 100 m, this type of printer can reliably reproduce many 3D objects accurately, in quiter conditions.

Enhancing thermal conductivity of epoxy with a binary filler system of h-BN platelets and Al2O3 nanoparticles

Epoxy resin is a common adhesive bonding material used to join dissimilar materials, especially in the electronics and aerospace industries. However, its low thermal conductivity and high coefficient of thermal expansion limit the direct use of epoxy in practical applications. In order to improve thermo-mechanical properties, we have prepared a series of epoxy composites using a binary system of hexagonal-boron nitride (h-BN) and aluminum oxide (Al2O3) fillers and analyzed the effect of the ratio of these fillers on the thermal conductivity of composites. While h-BN platelets form the main thermal conductive network, Al2O3 nanoparticles bridge the separated h-BN platelets to build more thermal conductive pathways. We proposed the improving of thermal conductivity as well as the mechanical properties of the epoxy matrix by incorporating h-BN and Al2O3 fillers at an optimum ratio.

Investigation on the electrical, thermal and mechanical properties of silicone rubber nanocomposites

Addition of alumina nano particles to silicone rubber (SR) has shown a significant improvement in electrical, mechanical and thermal properties of the SR nanocomposites. Static contact angle and water droplet-initiated corona inception voltage exhibited a marginal change on inclusion of nano alumina into SR matrix. Alumina filler improved the corona ageing resistance of the composites; however, a marginal reduction in the rate of hydrophobicity recovery is observed. Laser induced breakdown spectroscopy proved as an effective tool to rank the performance of the SR nano composites. Variation of crater depth with energy of laser pulse and number of laser pulses follows the exponential relation. Plasma temperature calculated by optical emission spectroscopy is in line with the amount of damage caused to the surface of the specimen by water droplet-initiated discharge. Dielectric response spectroscopic studies indicate that inclusion of nano fillers has resulted in lower interfacial polarization and lower imaginary permittivity. It is observed through dynamic mechanical analysis that the composites have higher storage modulus and the activation energy compared to base SR.

The dimensional stability assessment of the composite honeycomb panel for the conditions of thermal and gravitational loading in a Near-Earth Orbit

The results of the numerical determination of the stress-strain state of the composite honeycomb panel under gravitational and thermal loads of varying intensity in a near-earth orbit are presented. As a simulation model of the structure under study, a typical structure of a composite cell panel with a known type of cell arrangement of honeycomb aluminum filler and reinforcement schemes for layers of carbon fiber material for upper and lower plates with known thermomechanical properties was chosen. To solve the problems of thermoelasticity, we used the finite element method in mathematical formulations for stationary thermal and quasistatic thermomechanical analysis. The distribution of the values of von Mises equivalent stresses in the structural elements of the honeycomb panel under thermal loads in the temperature range from -80 to +80 is determined. The longitudinal and transverse deflections of the honeycomb from the action of thermal loads of various intensities in the near-earth orbit are found. The limiting value of the temperature difference between the outer surfaces of the plates, which ensures the thermal stability of the composite honeycomb panel, has been established. The maximum deflections of the honeycomb have been found out from gravitational and thermal stresses in the near-Earth orbit.

Experimental Analysis on the Application of Polymer Matrix Composites Containing Al2O3 for Automotive Lamp Reflector

As automotive lamps are highly integrated, the heat generated from bulbs reduces the light quantity and lifespan of the bulbs. Numerous studies have been actively conducted worldwide on heat dissipation designs and material modifications for heat release. In this study, an analysis was carried out of the mechanical, thermal, and morphological characteristics of Polybutylene Terephthalate (PBT) and Polyamide (PA6) matrix composites containing alumina filler; further, their flowability and injection moldability were also studied. The PA6 matrix that was subjected to an addition of 60% alumina was selected as the sample. To compare the performances of the selected composites with that of the fog lamp reflector manufactured with conventional PBT, fog lamp reflectors were fabricated. When 60% alumina was added, the thermal conductivity was improved. Thus, the maximum temperature of the lamp reflector was reduced, and the heat was transferred to the surroundings; this was in contrast to the fog lamp reflector fabricated with conventional PBT.

Dry sliding and abrasive wear behaviour of Al-7075 reinforced with alumina and boron nitride particulates

Abstract Present research examination focuses on the surface morphology; mechanical properties and wear conduct of Al-7075 metal matrix composites reinforced with alumina and hexagonal boron nitride fillers. Particulate reinforced Al-7075 metal matrix composites were manufactured following the two step stir casting method with differing the weight percentage (2.5 and 5) of reinforcement. Uniform dispersion of alumina and hexagonal boron nitride in pure alloy was verified by optical microstructure. The fabricated samples were subjected to abrasion using dry sand rubber wheel abrasive wear test rig by varying the abrading distance and the applied normal load. Silica sand of particle size 350–400 µm was used as abrasive medium. Mechanical and dry sliding wear test results indicated that both alumina and hexagonal boron nitride fillers show improved mechanical properties and wear resistance. From the abrasive wear test results, it was recognized that the wear resistance of composites is increased by increasing the weight percentage of reinforcements and the reinforced composite gave better resistance against abrasion than the control sample (Al-7075). Further, it was adjudicated that 5 wt% micro hexagonal boron nitride reinforced Al-7075 composite prompts predominant abrasion resistance. Finally, it was presumed that hexagonal boron nitride and alumina fillers gracefully and successfully improved morphological, mechanical, and also the wear properties of Al-7075 alloy for various engineered load-bearing applications.

Optimization of modifier deposition on the alumina surface to enhance mechanical properties and cavitation resistance

Composites based on poly(methyl methacrylate), dimethyl itaconate matrix and alumina particles were prepared. Ferrous oxide-doped alumina particles (Al2O3 Fe) and commercial alumina nanoparticles (Al2O3 n) modified with (3-aminopropyl)trimethoxysilane (AM) and methyl esters of linseed oil fatty acids (biodiesel—BD) were used as reinforcement. The mechanical properties of the prepared composites, containing 1, 3 and 5 wt% of surface-modified alumina particles, are compared to a neat polymer matrix. The particles were characterized by single-beam Fourier transform infrared spectroscopy, thermogravimetry and differential scanning calorimetry. The mechanical properties of the composites were determined by micro-Vickers hardness and impact testing. The morphology of the surface of the composites exposed to cavitation was observed through a field emission scanning electron microscope. AFM analysis was used to compare surface features seen using the SEM and to interpret the surface degradation properties. The hardness, cavitation resistance and high-impact energy resistance of the composites are better in the case of AM surface modification of alumina fillers, but biodiesel modified particles have comparable mechanical properties and a stabilized Al–O–Si bond that could be important when a composite is exposed to humidity or a wet environment.

Fabrication and Characterization of Nano-filled Polymer Composites

Polymers are essential matrix materials for fabricating advanced composites. The reinforcing materials take many forms. In addition to continuous fibers, filler reinforced was used. In this work, the influence of incorporation nano-metal particles to glass fiber/epoxy composites was investigated. Aluminum was used as metal nanoparticles. Nano and Micro fillers was sonicated with epoxy resin by ultrasonic processor to ensure good distribution of fillers. The composite laminate was fabricated by hand lay-up technique. Woven glass fiber was used as fiber reinforcement. The volume fraction of glass fiber was 35%. The aluminium fillers were added with weight percentage of 0.2 wt%, 2-wt% and 4-wt%. The results show that the fabricated composites have shown an improvement in tensile, flexural, and hardness strengths as compared to neat glass fiber/epoxy composites. The failure strain increased in both the tensile and flexural tests. Increasing the weight content of nano aluminium particles to 4-wt % decrease the tensile strengths. However, increasing the aluminium micro-particles to 4 wt% has shown enhancement in mechanical properties. Micro aluminum fillers indicated a maximum of 195 MPa at 4wt% Al. A higher weight fraction of nano Al in the epoxy resin had showed little agglomerations. The water absorption values observed were lower for composite filled with nanoparticle. The flexural strength increased by 52.21%, flexural strain by 21.4 %, and flexural modulus by 76.57% compared to GFRE.

Effect of Zirconia and Alumina Nanofillers on the Microstructure and Some Properties of Flowable Composite

Purpose:studying the effect of reinforcing flowable composite with different concentrations of zirconia and alumina nanofillers on its microstructure, complex viscosity, colour changes, flexural strength and degree οf cοnversiοn.Materials and Methods:180 samples were divided according to nanofillers type into two groups(n=90),each group was subdivided into five subgroups according to concentration of fillers (0%,2%,4%,8%and16%)(n=20). Each group was subdivided into 4 subdivisions according to type of test performed(n=5).Samples were characterized by SEM, viscosity was measured by oscillatory rheοmeter, colour changes was measured using spectrophotometer, fǀexural strength was measured by three point bending test and degree of conversion was measured by FTΙR.Results: SEM showed homogenous distribution of zircοnia and alumina np at 2&4wt%, some agglomeration for both types of fillers at 8wt%. For complex viscosity, zirconia np at 16wt% at 25℃ had higher median value compared to 37℃ (6.17), Alumina np at 2wt% and 4wt% at 25℃ had higher median value compared to 37℃ (5.665),(8.516) respectively. For colour changes, zr& al np at 4wt% showed the highest mean values(10.2±1.5,11.1±1.4) respectively. Ιn flexural strength, zirconia filler at 4wt% had higher mean value (137.8±18.1MPa)compared to alumina filler(94.4±16.9 MPa). For DC, 4wt% for both zr& al np showed the highest mean values compared to other groups (66.4±2.4, 64.3±0.82) respectively.Conclusion: Viscosity increased as the concentration of nanofillers increased. Ιncorporation of nanofillers affect the cοlour of the flowable composite. Fǀexural strength was improved with increasing the concentration of zirconia nanofillers, while it decreased with alumina nanofillers. DC increased as the filler concentration increased till 4 wt.% then decreased.

Ultrasonic Evaluation at the Interface of Aluminum/Steel Obtained by TIG Welding

Aluminum filler (Al-5%Si) is bonded on steel substrate by gas tungsten arc welding process under different current setting conditions. After welding a thorough metallographic analyses using optical and scanning electron microscopy were carried out to observe Al-Steel interface. Ultrasonic measurements by immersion and scanning acoustic microscopy were made to characterise the bond at Al-Steel interface. The ultrasonic wave reflected from the Al-Steel interface clearly indicated the more debonded area when the welding current is changed from direct current straight polarity (DCSP) mode to alternate current high frequency (ACHF) or the welding current in case of current for DCSP mode is reduced. This may be attributed either adequate amount of oxides along with intermediate phase make the bond interface rough and uneven due to introduction of ACHF mode or debonded areas are higher due to lower heat input when the current reduced to 125 amps from 150 amps in DCSP mode. Whereas smooth and even bond interface due to uniform heat input resulted stable Al-Steel interface and the mapping of bonded area by ultrasonic measurement showed spectrum of minimum peak for using current of 150 amps in DC mode. Thus the non-destructive assessments of interface between dissimilar materials through ultrasonic measurements could be important tools for evaluating the state of the bond.