Aluminum Nitride Particles Research Articles

Systematic experimental investigation of filtration losses of drilling fluids containing silicon oxide nanoparticles

This paper presents the results of silicon oxide nanoparticles-incorporated drilling fluid filtration through a porous medium with different permeability. A water-based clay suspension was used as a basic model for creating investigated fluid samples. AlN (aluminium nitride) particles were used as a dispersed phase. The concentration of microparticles varied from 0.5 to 4.00 wt%, while the microparticles size varied from 1 to 10 μm. The concentration of SiO2 nanoparticles was changed within the range of 0.25 and 4.00 wt%, while the nanoparticles size varied from 5 to 100 nm. It was shown that filtration of drilling fluids with nanoparticles inclusions depends on their concentration, size and material, the concentration and size of microparticles and the pore sizes of ceramic filters. The addition of the nanoparticles leads to a significant reduction in filtration of a microsuspension and affects the structure and thickness of a cake formed on the surface of a filter. The main novelty of this work lies in the fact that the effect of the addition of nanoparticles on filtration losses depends on the ratio between nano and microparticles. It was shown that the positive effect of nanoparticle additives on filtration losses is determined not only by the properties of nanoparticles (size and concentration), but also by the properties of microparticles contained in the drilling fluid, as well as the characteristics of the rock (pore size).

Influence of AlN particles on microstructure, mechanical and tribological behaviour in AA6351 aluminum alloy

In the current trend, the hard ceramic particles reinforced aluminum matrix composites (AMCs) is extensively being exploited as a composite which shall be utilized for various engineering applications. In the present research, the Al-Si-Mg (AA6351) composite incorporated with aluminium nitride (AlN) filler were prepared via novel and low cost melt stirring process. This study was conducted using AA6351 aluminum alloy in conjunction with AlN particles whose percentages of incorporation were 4%, 8%, 12%, 16% and 20 wt% in the ascending. The stir casted composites and the base alloy were characterized via scanning electron microscope (SEM) and energy dispersive x-ray analysis (EDAX). EDAX pattern proves the occurrence of AlN filler contents in the synthesized AMCs. SEM studies exhibit the even dispersion of the reinforcement particles in the Al matrix. The effects of AlN contents on the mechanical characteristics of AA6351 matrix composites were examined. The dry sliding wear characteristics of the prepared composites was tested employing pin on disc machine. The mechanical and wear behavior of the AMCs had shown a great enhancement by the incorporation of AlN particles into AA6351 matrix alloy. The test outcomes discovered that Al/20 wt% AlN composites had revealed superior wear resistance, hardness, yield strength and tensile strength than the AA6351 base alloy.

Experimental investigation on mechanical properties of AA7075-AlN composites

Abstract Hard ceramic particle reinforced aluminum matrix composites (AMCs) are considered a distinct category of advanced materials which command outstanding strength, good corrosion resistance and excellent wear resistance compared to conventional materials. In the present work, an Al-Zn-Mg aluminum alloy-based metal matrix composite was prepared by stir casting. The AA7075 matrix was reinforced with 0, 3, 6, 9 and 12 wt.-% aluminum nitride particles for producing AMCs. Flexural strength, tensile strength and micro-hardness were studied. The microstructure of the matrix alloy and the composites was examined by scanning electron microscopy (SEM). Micron-sized aluminum nitride particles were added to the aluminum matrix to enhance the micro-hardness and the flexural and tensile strength of the composite. SEM micrographs reveal the fairly uniform dissemination of aluminum nitride particles in the composite. The results obtained indicate that the mechanical properties of the composite were increased with an increase in weight percentages of the aluminum nitride reinforcement content.

Manipulating thermal conductivity of polyimide composites by hybridizing micro- and nano-sized aluminum nitride for potential aerospace usage

Electrically insulating yet thermally conductive polymer-based composites are highly sought after in aerospace field. In this work, for the first time, electrically insulating but thermally conductive polyimide (PI) composites are fabricated by simultaneously incorporating micro- and nano-sized aluminum nitride (AlN) particles via a simple, economic, and scalable method of ball milling and subsequent hot-pressing process. The thermal conductivity, dielectric, and mechanical properties of the PI composites depend on the ratio of micro-sized AlN (m-AlN) to nano-sized AlN (n-AlN) and the total content of AlN in the PI composites. The thermal conductivity of the PI composites with 40 wt% m-AlN and 20 wt% n-AlN is 1.5 ± 0.05 W·m−1·K−1, which is 10 times higher than that of bare PI. The PI composites hold a great potential in aerospace industries.

Preparation and characterization of epoxy-based composite with multilayered structure and high thermal conductivity

A multilayered thermally conductive composite with ternary system of heat conductive fillers-thermally conductive films-epoxy matrix was prepared through a facile process of layer-by-layer stacking, pre-curing and hot-pressing. The thermally conductive films (boron nitride nanosheets/cellulose nanofiber) with high in-plane thermal conductivities were employed as the heat conductive medium, while the platelet-shaped hexagonal boron nitride and the particle-shaped aluminum nitride were utilized as heat conductive fillers for enhancing the perfection of the thermally conductive network. A horizontally heat conductive network was constructed within the epoxy matrix under the joint contribution of the horizontally aligned hexagonal boron nitride platelets and the parallelly spread thermally conductive films through hot-pressing. The aluminum nitride particles acted as linking points, filling the gaps between hexagonal boron nitride platelets, while constructing the thermally conductive path in the vertical direction. Thanks to the introduction of thermally conductive films and the good orientation of boron nitride platelets, the in-plane thermal conductivities of the composites increased with increasing of film layer number. With film layer number of 9, and filler content of 30 wt% (aluminum nitride/boron nitride (1:1)), the in-plane thermal conductivity of the composite was as high as 8.53 W m−1 * K, which showed an enhancement of 4165% than that of the pure epoxy matrix, and an improvement of 613% compared to that of the composite without multilayered structure. Meanwhile, the out-of-plane thermal conductivity exhibited a slightly deceased tendency as film layer number increased, but it still reached 0.87 W m−1 * K with film layer number of 9, which was 335% higher than that of the pure epoxy. In addition, the multilayered composite also possessed good thermal stability, enhanced stiffness, as well as low dielectric constant and dielectric loss, which shows a potential application in thermal management for packaging of integrated circuit and microelectronic devices.

Synergistic Effects of Various Ceramic Fillers on Thermally Conductive Polyimide Composite Films and Their Model Predictions.

In this study, thermally conductive composite films were fabricated using an anisotropic boron nitride (BN) and hybrid filler system mixed with spherical aluminum nitride (AlN) or aluminum oxide (Al2O3) particles in a polyimide matrix. The hybrid system yielded a decrease in the through-plane thermal conductivity, however an increase in the in-plane thermal conductivity of the BN composite, resulting from the horizontal alignment and anisotropy of BN. The behavior of the in-plane thermal conductivity was theoretically treated using the Lewis–Nielsen and modified Lewis–Nielsen theoretical prediction models. A single-filler system using BN exhibited a relatively good fit with the theoretical model. Moreover, a hybrid system was developed based on two-population approaches, the additive and multiplicative. This development represented the first ever implementation of two different ceramic conducting fillers. The multiplicative-approach model yielded overestimated thermal conductivity values, whereas the additive approach exhibited better agreement for the prediction of the thermal conductivity of a binary-filler system.

Tracking, erosion and thermal distribution of micro‐AlN + nano‐SiO 2 co‐filled silicone rubber for high‐voltage outdoor insulation

Thermal depolymerisation induced tracking and erosion of polymeric insulators is one of the key insulation failure modes and this process adversely affects the reliability of power delivery networks. This study reports the tracking, erosion and thermal distribution of micron-AlN and micron-AlN + nano-SiO2 co-filled silicone rubber composites. A tracking-erosion model is presented to explain how the co-filled set of particles directly affects such mechanisms. Aluminium nitride (AlN: 5–10 μm) and silica (SiO2: 20 nm) particles were procured for fabricating test samples. The inclined plane test according to IEC 60587 was carried out using tracking voltage method 2 with an initial applied voltage of 3 kV and a ramping rate of 0.25 kV/h over the duration of 240 min. Measurement results show co-filled composites exhibit significantly lower physical tracking and erosion as compared to micron-AlN filled composites. Thermal accumulation and average leakage current in co-filled composites are found noticeably lower than micron-filled counterparts. Moreover, the increased surface area of the combined co-filled particles in the composites provides better scattering and reduce secondary electron collision. This may impede the release of high energy causing thermal degradation.

Effects of thermal properties on tracking and erosion resistance of micro-ATH/AlN/BN filled silicone rubber composites

Silicone rubber is a hydrophobic polymer which is widely employed for high voltage outdoor insulation. The material offers excellent electrical performance under contaminated environments. However, pristine silicone rubber has low thermal properties and this may cause tracking and erosion failure due to severe dry band arcing and ohmic heating on the insulating surface. This work investigates the effect of material thermal characteristics on the tracking and erosion resistance of silicone rubber filled with micron sized alumina tri-hydrate (ATH), aluminum nitride (AlN) and boron nitride (BN) particles. Composites with different loading were synthesized by dispersing particles in pristine room temperature vulcanizing (RTV) silicone rubber and IEC 60587 inclined plane test (IPT) was conducted to evaluate tracking and erosion resistance. Apart from physical parameters and leakage current, an infrared thermal imager was used to measure the surface temperature distribution during the course of IPT. Experimental results showed tracking and erosion resistance is significantly enhanced with addition of BN particles followed by ATH. AlN composites exhibit poor tracking and erosion resistance, similar to pristine silicone rubber. It is concluded that addition of BN-composites improves ability to impede the tracking and erosion process, the reasons being better thermal stability and enhanced thermal conduction in the discharge region. On the other hand, infrared analysis revealed thermal accumulation is remarkably higher in AlN-composites which promotes dry band arcing and results in tracking and erosion failure.

Enhanced through-plane thermal conductivity of PTFE composites with hybrid fillers of hexagonal boron nitride platelets and aluminum nitride particles

Due to the strong horizontal orientation tendency of hexagonal boron nitride (hBN) platelets, hBN/polymer composites generally exhibit high in-plane thermal conductivity while low through-plane thermal conductivity. In this work, hBN platelets and aluminum nitride (AlN) particles are used as hybrid fillers to improve the thermal conductivity of polytetrafluoroethylene (PTFE). AlN particles effectively disrupt the alignment of hBN platelets along the lateral direction during the compression processing, which can be proved by the results of SEM and XRD. At 30 vol% filler loading, a high through-plane thermal conductivity as 1.04 W/mK is achieved, which is 3.8 times that of neat PTFE. The significantly increased thermal conductivity is related not only to the synergetic effect of hybrid fillers, but also the reduced in-plane orientation degree of hBN. Hashin-Shtrikman model is also used to quantify the filler connectivity within polymer matrix. The result suggests that filler morphology and orientation influence the filler connectivity and both control the effective thermal conductivity of composites.

Optimizing the Tribological Behavior of Hybrid Copper Surface Composites Using Statistical and Machine Learning Techniques

Copper-based surface composite dispersed with varying fractions of hybrid reinforcement was fabricated through friction stir processing (FSP). Hybrid reinforcement particles were prepared from aluminum nitride (AIN) and boron nitride (BN) particles of equal weight proportion. Based on design of experiments, wear characteristics of the developed copper surface composites were estimated using pin-on-disk tribometer. Experimental parameters include volumetric fraction of hybrid reinforcement particles (5, 10, and 15 vol %), load (10, 20, 30 N), sliding velocity (1, 1.5, and 2 m/s), and sliding distance (500, 1000, and 1500 m). Microstructural characterization demonstrated uniform dispersion of hybrid reinforcement particles onto the copper surface along with good bonding. Hardness of the developed surface composites increased with respect to increase in hybrid particle dispersion when compared with copper substrate while a reduction in density values was revealed. Analysis on wear rate values proved that wear rate decreased with increase in hybrid particle dispersion and increased with increase in load, sliding velocity, and distance. Analysis of variance (ANOVA) specified load as the most significant factor over wear rate values followed by volume fractions of particle dispersion, sliding velocity, and distance. Regression model constructed was found efficient in predicting wear rate values. Analysis of worn out surfaces through scanning electron microscopy (SEM) revealed the transition of severe to mild wear with respect to increase in hybrid reinforcement particle dispersion. A feed forward back propagation algorithm-based artificial neural network (ANN) model with topology 4-7-1 was developed to predict wear rate of copper surface composites based on its control factors.

Microstructure and mechanical properties of hard ceramic particulate reinforced AA7075 alloy composites via liquid metallurgy route

Particulate reinforced aluminium matrix composites (PRAMCs) are extensively substituting the conventional aluminium alloys in several applications and components in aircraft, marine, construction and automobile industries. Research is being carried out across the globe to enrich the mechanical, tribological and physical properties of PRAMCs using novel manufacture techniques and reinforcements. In this article, an attempt is made to analyse the influence of the different weight fraction of aluminum nitride (AlN) particle reinforced composites. Aluminium alloy AA7075 was reinforced with several quantities (0, 5, 10 and 15 wt%) of AlN through stir casting route. The microstructures, as well as mechanical properties of the manufactured composites are analysed. The manufactured composites were inspected by using Optical Microscope. Optical micrographs revealed the nearly uniform dissemination of reinforcement particles in the matrix alloy (AA7075). The hardness, as well as the tensile strength of the composite, has increased with the increase in weight fraction of aluminium nitride particulates in the AA7075 matrix.

Low-temperature spark plasma sintering of calcium stabilized alpha sialon using nano-size aluminum nitride precursor

Calcium stabilized alpha-sialon ceramic was synthesized using spark plasma sintering (SPS). The size effect of aluminum nitride precursor (1μm and 50nm) on the phase analysis, microstructural and mechanical characteristics of the processed sialon was studied. Alongside the size of AlN precursor, holding time and sintering temperature were also varied in order to assess the degree of densification, phase transformation and its subsequent effect on the mechanical properties of these materials. The development of alpha phase was found to be strongly dependent on the particle size of the aluminum nitride (AlN) precursor. Interestingly, this novel approach of changing particle size from micro to nano-level combined with the SPS process resulted in the formation of alpha-sialon ceramic at much lower than previously reported sintering temperature i.e. 1500°C as compared to 1700/1800°C. Surface oxide layer associated with AlN particles resulted in the formation of additional beta phase along with major alpha phase in the final product. The sialon product synthesized from micron-size AlN particles (1μm) at a sintering temperature of 1500°C exhibited Vickers hardness value HV10, of 18GPa and moderate fracture toughness of 5.6MPa√m. However, sialon materials synthesized from nano-size AlN particles (50nm) showed a hardness value of 14GPa while displaying an improved fracture toughness of 7MPa√m. Increase in holding time resulted in a slight increase in densification of these materials, however its influence on mechanical properties was less significant as compared to the effect of particle size of aluminum nitride staring powder precursor.

A Multiscale Understanding of the Thermodynamic and Kinetic Mechanisms of Laser Additive Manufacturing

Abstract Selective laser melting (SLM) additive manufacturing (AM) technology has become an important option for the precise manufacturing of complex-shaped metallic parts with high performance. The SLM AM process involves complicated physicochemical phenomena, thermodynamic behavior, and phase transformation as a high-energy laser beam melts loose powder particles. This paper provides multiscale modeling and coordinated control for the SLM of metallic materials including an aluminum (Al)-based alloy (AlSi10Mg), a nickel (Ni)-based super-alloy (Inconel 718), and ceramic particle-reinforced Al-based and Ni-based composites. The migration and distribution mechanisms of aluminium nitride (AlN) particles in SLM-processed Al-based nanocomposites and the in situ formation of a gradient interface between the reinforcement and the matrix in SLM-processed tungsten carbide (WC)/Inconel 718 composites were studied in the microscale. The laser absorption and melting/densification behaviors of AlSi10Mg and Inconel 718 alloy powder were disclosed in the mesoscale. Finally, the stress development during line-by-line localized laser scanning and the parameter-dependent control methods for the deformation of SLM-processed composites were proposed in the macroscale. Multiscale numerical simulation and experimental verification methods are beneficial in monitoring the complicated powder-laser interaction, heat and mass transfer behavior, and microstructural and mechanical properties development during the SLM AM process.

Effect of the Grafting Reaction of Aluminum Nitride on the Multi-Walled Carbon Nanotubes on the Thermal Properties of the Poly(phenylene sulfide) Composites.

In this study, the PPS/MWCNTs/AlN composite was prepared with poly(phenylene sulfide) (PPS), covalent functionalized multi-walled carbon nanotubes (fMWCNTs), and aluminum nitride (AlN) via melt-blending techniques. The AlN is a fascinating non-oxidizing ceramic material having the highest thermal conductivity among the ceramic materials. In order to introduce the functional groups on the surface of the AlN particles, a silane coupling agent was used as it is able to graft with the functional groups on the covalent functionalized MWCNTs. The silanization reaction of the AlN was confirmed qualitatively and quantitatively by FT-IR (Fourier Transform Infrared Spectroscopy), and XPS (X-ray Photoelectron Spectroscopy). The grafting reaction of the AlN particles on the MWCNTs was confirmed using UV–Vis (Ultraviolet-Visible Spectroscopy), FE-SEM (Field-Emission Scanning Electron Microscopy) and FE-TEM (Field-Emission Transmission Electron Microscopy) images. The grafting reaction was accomplished by observing the change of the transmittance, the morphology of the AlN particle bonded to the MWCNTs. For the morphological changes of the fractured surface of the PPS/MWCNTs/AlN composites by FE-SEM, the hybrid filler was homogeneously dispersed on the PPS matrix when the AlN particle was grafted on the MWCNTs. The homogeneous distribution of the hybrid filler acts as a heat transfer path, which led the higher thermal properties, such as thermal conductivity, thermal resistance, and melting temperature than those of not grafted MWCNTs.

Thermal conductivity of epoxy resin composites filled with combustion‐synthesized AlN powder

The thermal conductivity of epoxy resin composites filled with combustion‐synthesized aluminum nitride (AlN) particles was investigated. The mixing of the composite constituents was carried out by either a dry method (involving no use of solvent) for low filler contents or a solvent method (using acetone as solvent) for higher filler contents. It was found that surface treatment of the AlN particles using a silane, 3‐aminopropyltriethoxysilane (APTES), increases the thermal conductivity of the resultant composites by a less amount compared to most of the values reported in other studies. This was explained by that the combustion‐synthesized AlN particles contain less OH or active sites on the surface, thus adsorbing less amounts of APTES. However, the thermal conductivity of the composites filled with the combustion‐synthesized AlN was found to be within the range of the values reported in other studies where commercially available AlN was used. Effects of several factors on the thermal conductivity of the epoxy resin composites were investigated including filler content (10‐60 vol%), particle size (2.5‐22.4 μm), oxygen content (0.22‐2.20 wt%) and with or without surface treatment. Within the ranges of the factors investigated in this study, it was found that the filler content has the greatest effect on the thermal conductivity of the composites. The effects of the other three factors on the thermal conductivity of the composites increase roughly with increasing filler content. Among the three factors, the effect of particle size on the thermal conductivity was found to be greater than that of the other two. POLYM. COMPOS., 39:E2125–E2133, 2018. © 2017 Society of Plastics Engineers

Epoxy composites filled with boron nitride and aluminum nitride for improved thermal conductivity

Epoxy composites containing boron nitride (BN) or aluminum nitride (AlN or Al2N3) particles have been studied with a view to obtaining increased thermal conductivity. The effect of these fillers on the cure reaction has been investigated by differential scanning calorimetry (DSC) for two systems, epoxy-diamine and epoxy-thiol, and for volume fractions up to about 35 % of these filler particles. For the epoxy-diamine system, the glass transition temperature of the fully cured system, the heat of reaction, and the temperature at which the peak heat flow occurs were all independent of the cure conditions, filler type and content. In contrast, the epoxy-thiol system shows a systematic effect of filler on the peak temperature for both fillers: there is an initial acceleration of the reaction, which diminishes with increasing content, and the reaction is even significantly retarded at high contents for BN. This is interpreted in terms of an improved interface between epoxy matrix and particles, with a consequent enhancement of the thermal conductivity of the epoxy-thiol composites.

Formation of Liquid Crystalline Order and Its Effect on Thermal Conductivity of AlN/Liquid Crystalline Epoxy Composite

ABSTRACTThe liquid crystalline (LC) order was introduced on aluminum nitride particles by the surface effect to increase the thermal conductivities of aluminum nitride/LC epoxy composites. X-ray diffraction and grazing incidence small-angle X-ray scattering analyses revealed that the LC epoxy resin cured on the surface of an α-Al2O3 substrate formed homeotropically aligned smectic layers to increase the thermal conductivity. Therefore, thermally treated aluminum nitride particles, which formed α-Al2O3 layers on their surfaces, were applied to prepare the composites with high thermal conductivity. The thermal conductivities of the resulting composites were 11–36% higher than those with the composites prepared using untreated aluminum nitride particles.

Thermal conductivity and dielectric properties of PEDOT:PSS-AlN filler reinforced water-soluble polymer composites

Abstract Poly(3,4-ethylenedioxythiophene):poly-(styrenesulfonic) (PEDOT:PSS) surface modification of aluminum nitride (AlN) fillers and the effects on thermal conductivity and dielectric properties of polyurethane (PU) based composites are investigated in this study. The compositions, microstructure, thermal stability, thermal conductivity, dielectric properties and volume resistivity of the PU based composites were characterized using Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetry (TGA), optical thermal analyzer (OTA), impedance analyzer (IA), respectively. It was observed that the thermal conductivity and thermal stability of the PU composites increased with increasing AlN content. After proper processing, the AlN particles could form a continuous dispersion, which would form a thermally conductive pathway within the polymer matrix. By adding 0–50 wt% AlN particles, the PU composites thermal conductivity was increased from 0.209 to 0.476 W/m-K. Furthermore, the thermal conductivity can be promoted to 0.764 W/m-K using PEDOT:PSS surface modification. The dielectric properties of the composites can also be adjusted by PEDOT:PSS surface modification. The dielectric constant of the PU based composites was increased from 7.58 to 400 at 10 kHz by adding 0–3 wt% PEDOT:PSS, which can act as an attractive candidate material for packaging, dielectric and embedded capacitors.

Assessment of microstructure and wear behavior of aluminum nitrate reinforced surface composite layers synthesized using friction stir processing on copper substrate

Aluminum nitride (AlN) is a potential ceramic particle to improve the wear resistance of copper surface. The present work is focused on synthesizing Cu/AlN (0,6,12,18vol%) copper matrix composites (CMCs) on pure copper substrates through friction stir processing (FSP). AlN particles were compacted into grooves machined on the surface of the copper plates. FSP was carried out under a set of fixed experimental conditions. The microstructural features were analyzed using optical, scanning and transmission electron microscopy. The wear behavior was assessed using a pin-on-disc apparatus. AlN particles were distributed homogenously in the surface composite. There were no clusters and segregation of AlN particles. The distribution was almost constant across the depth of the surface composite. There was a good interfacial bonding between AlN particles and the copper matrix. There was no major change in shape and size of AlN particles subsequent to FSP. Fine equiaxed grain structure was observed in the composite induced by dynamic recrystallization and pinning effect of AlN particles. The dry sliding wear behavior of the composite surface was reported in detail.

Microstructural, mechanical and tribological behavior of aluminum nitride reinforced copper surface composites fabricated through friction stir processing route

This work focuses on investigating the effect of Aluminum Nitride (AlN) for its 5, 10 and 15vol% dispersion onto the surface of copper matrix through friction stir processing route. Microstructural observation confirms for the breaking down of grain size thus implying dynamic recrystallization process and also uniform dispersion along with good bonding of AlN particles with copper matrix. Hardness of the developed surface composite exhibits an increasing trend which is supposed to be the effect of dispersed particles and grain size reductions. Tensile tests prove that surface composites yields incremental behavior over strength with rise in AlN vol% even though values were far behind the strength offered by pure copper. Fractured surface micrograph of tensile specimens indicates reduction in ductility of the developed composite with dispersion of AlN particles. Wear resistance showcased a positive inclination with respect to reinforcement increments while the frictional coefficient value also possessed a propensity to increase. The fluctuation of frictional coefficient value diminished with AlN addition mainly because of reduced contact between copper and the rotating counterpart besides carrying away the exerted loads by these AlN particles. Detailed characterization of worn out surface prove that with AlN addition wear rate through adhesion has also reduced significantly.