Silicon Nitride Particles Research Articles

Ti と窒化ケイ素粉末混合焼結体の In-situ 分解反応挙動と摩耗特性

Ti と窒化ケイ素粉末混合焼結体の In-situ 分解反応挙動と摩耗特性

Reinforcement of Silicon Nitride Particles with AZ81 Magnesium Alloy Prepared by Stir Casting

Magnesium is one of the promising materials for low-temperature conditions. Currently, magnesium is well known as developed magnesium matrix composites (MMCs) in automotive applications. Particles that are reinforced with MMCs materials having excellent properties of castability, high modulus of elasticity and high specific strength. But in this research, AZ81 Mg alloy is reinforced with silicon nitride for the study of material toughness, impact strength and hardness. Stir casting process was used for the casting of samples. After casting the samples, material toughness, impact strength and hardness were evaluated. Under this process, Si3N4 particles were uniformly distributed in AZ81 matrix and wellbonded composite formation. The result of the mechanical test shows a huge decrement in material toughness and increment in hardness as particle weight fraction of Si3N4 particles increases.

The influence of carbon additions on structure and properties of composites manufactured via powder metallurgy method

This paper presents an influence of reinforcement and additions types on tribological properties for composite materials produced for potential application in high loaded friction point. The influence of carbon nanotubes or amorphous form of carbon on tribological properties was subject of authors' interest. A technology of materials manufacturing based on preparation of composite powders using high energy ball milling, with subsequent hot pressing in the semi-liquid phase. All materials based on an aluminum alloys, with silicon carbide (SiC) or silicon nitride particles (Si3N4) applied as a reinforcement. As a additions 1 wt.% of multiwalled carbon nanotubes (CNT) or 5 wt.% of glassy carbon particles (GCp) were used. A proper parameters selection (speed, powder to ball ratio, time ect.) of high energy milling led to fragmentation of ceramic particles up to nano- or submicro scale with desirable homogenization in whole volume of solid material. Due to partially crushed of glassy carbon particles, their size was between 2 – 200 μm. However GCp revealed also proper distribution in volume of composite. Moreover, the good quality of bonding between matrix and reinforcement particles were achieved due to high energy during milling. For manufactured materials a rating of tribological properties (coefficient of friction, wear rate, ect.) at ambient and high temperature were made. The research confirmed that, due to desirable coefficient of friction (COF) value and low mass loss, manufactured materials can be applied in automotive industry, eg. for brake pads. A high stability of COF on desirable value (0.5 – 0.8) was observed up to temperature higher than 500 °C. The application of carbon additions resulted in increasing of friction properties. The material with silicon nitride as a reinforcement and glassy carbon particles addition revealed the best friction properties between analysed materials.

SHS of ultrafine and nanosized Si3N4 powders: The effect of inorganic and organic additives on the microstructures, morphology, and phase compositions of products

The relationship between the microstructure and phase composition of a product obtained by selfpropagating high-temperature synthesis (SHS) and different reaction mechanisms is studied using the example of silicon nitride. The formation of nanosized silicon nitride particles upon the combustion of silicon in nitrogen and other phenomena typical of substances of this class, such as self-organization and self-assembly, are observed. The chemical condensation SHS of silicon nitride is studied in the presence of inorganic salts as modifying additives. The resulting Si3N4 powders have a structure of secondary spherical particles being composed of primary ultrafine and nanosized ones. The Si3N4 powders under study were fractionated depending on the particles size and microstructure by chemical dispersion. Ultrafine particles of the light fraction form as homogeneous rods by the conventional vapor–liquid–crystal mechanism. The fine-crystalline fractions are formed by hollow crystals assembled into globules. Microstructural analysis shows that the crystal walls consist of nanosized Si3N4 particles. The effects of organic additives introduced into the charge stock on the phase formation, microstructure formation, and particle size of SHS silicon nitride are studied. The combustion products are found to be composite powders whose phase compositions depend on the additive and the synthesis conditions. According to the data from X-ray powder diffraction and chemical analysis, the final products can contain up to 100% of β-Si3N4, up to 60% of α-Si3N4, up to 80% of SiC, and up to 70% of Si2N2O. It is shown that silicon nitride-based composite powders containing silicon carbide and/or silicon oxynitride can be obtained in one step. The role of ferric chloride hexahydrate as the SHS catalyst is studied. An ultrafine structurally homogeneous powder of β-Si3N4 is obtained in the presence of FeCl3 · 6H2O.

Production and some properties of Si3N4 reinforced aluminium alloy composites

The present research work focuses on the production of aluminium (AA6082-T6) matrix composites reinforced with various weight percentage of silicon nitride particles by conventional stir casting route. The percentage of reinforcement is varied from 0 wt.% to 12 wt.% in a stage of 3%. The microstructures and mechanical properties of the fabricated aluminium matrix composites are investigated. The scanning electron microstructure images reveal the presence of Si3N4 particles in the aluminium matrix. The distribution of Si3N4 particles has also been recognized with X-ray diffraction technique. The mechanical properties such as ultimate tensile strength and hardness have improved at the cost of reduction in ductility with increase in weight percentage of silicon nitride particulates in the aluminium metal matrix. The density and porosity of the composites also show an increasing trend with increase in volume fraction of Si3N4 particles in the aluminium matrix.

Microstructural Observation and Phase Analysis of Sn-Cu-Ni (SN100C) Lead Free Solder with Addition of Micron-Size Silicon Nitride (Si<sub>3</sub>N<sub>4</sub>) Reinforcement

The effect of micron-size silicon nitride (Si3N4) particles additions, up to 1.0 wt. % on Sn-Cu-Ni (SN100C) solder alloy was investigated. Sn-Cu-Ni composite solder were prepared via powder metallurgy (PM) technique. Different percentages of Si3N4(0, 0.25, 0.5, 0.75 and 1.0 wt. %) were added into the alloy. Result revealed that reinforcement was well distributed between the grain boundaries which could positively affect the properties of the composite solder.

Polymethyl methacrylate based phase change microencapsulation for solar energy storage with silicon nitride

Silicon nitride was applied to enhance the thermal performance and mechanical properties of phase change microencapsulation (PCM) based on polymethyl methacrylate (PMMA) shell and n-octadecane core. ‘A molecular bridge’ was constructed to modify the surface of silicon nitride and to eliminate boundary layer between inorganic silicon nitride particle and organic PMMA shell. Thus, an innovative modified silicon nitride phase change microencapsulation (MPCM) with which silicon nitride uniformly disperses in PMMA as shell and n-octadecane as core was successfully prepared. The microencapsulation was characterized using Fourier transformed infrared spectrophotometer (FTIR), field emission scanning electron microscope (FESEM), differential scanning calorimeter (DSC) and thermal gravimetric analyzer (TGA). A micro/nano-hardness tester was also employed, in order to investigate mechanical performance of shell. The result shows that the MPCM containing 66.4% n-octadecane has 121.11J/g latent heats of melting and 122.01J/g latent heats of crystallization with the modified silicon nitride percentage up to 10wt.%. The modified silicon nitride could not only enhance thermal performance, but also improve mechanical strength up to 16.24mN which is 4times higher than that of PCM. Additionally, wrinkles on the surface of MPCM improved special surface area as well as adaptation of volume changes during phase change process. The prepared MPCM is expected to exhibit better performance in solar energy storage technology.

Sr-anorthite glass ceramic with enhanced crack resistance, reinforced with silicon nitride particles

It is demonstrated that composite materials based on Sr-anorthite glass ceramic can be synthesized with finely dispersed α-Si3N4 and β-Si3N4 powders introduced as fillers. A study of the influence exerted by the polymorphic forms of fillers, their morphology, dispersity, and concentration and also by the nature of the matrix on the synthesis, structure, and properties of the composites demonstrated that the mechanism and temperature range of sintering in syntheses of materials are determined by the nature of the matrix and the degree of densification and the structure of the composite depend on the concentration, dispersity, and shape of filler particles, their phase composition, and wettability of the glass-phase matrix. In syntheses of glass-crystalline composites by the hot compaction method, raising the filler content from 10 to 70 vol % leads to a substantial decrease in the density of the materials (by 20%); the maximum content of the filler should not exceed 30 vol %. The use of both α-Si3N4 and β-Si3N4 in an amount of 30% made it possible to raise the critical stress intensity coefficient of the strontium-aluminosilicate matrix by more than a factor of 2. A study of the thermal properties of the composites demonstrated that the glass-crystalline matrix can protect nonoxide fillers from oxidation by atmospheric oxygen at elevated temperatures, with the oxidation onset temperature increased by 300°. The developed class of composites is promising for application in airspace technology, chemical industry, and motor-vehicle construction.

Parametric Study of Dry Sliding Wear of Aluminium Metal Matrix Composites by Response Surface Methodology

The effect of silicon nitride particles on the dry sliding wear of Al6082 alloy composites manufactured by conventional stir casting method have been investigated. The percentage of reinforcement were varied from 0 to 12% in a step of 3. Response surface methodology has been used to plan and analyse the experiments. Result showed that sliding distance is the most influential factor and percentage reinforcement is the factor which affects the wear least. The interaction of percentage reinforcement and load, percentage reinforcement and sliding distance, load and sliding distance, sliding speed and sliding distance also have significant effects on the wear.

Pulse electrodeposition and corrosion properties of Ni–Si3N4 nanocomposite coatings

The development of modern technology requires metallic materials with better surface properties. In the present investigation; Si3N4-reinforced nickel nanocomposite coatings were deposited on a mild steel substrate using pulse current electrodeposition process employing a nickel acetate bath. Surface morphology, composition, microstructure and crystal orientation of Ni and Ni–Si3N4 nanocomposite coatings were investigated by scanning electron microscope, energy dispersive X-ray spectroscopy and X-ray diffraction analysis, respectively. The effect of incorporation of Si3N4 particles in the Ni nanocomposite coating on the micro hardness, corrosion behaviour has been evaluated. Smooth composite deposits containing well-distributed silicon nitride particles were obtained and the crystal grains on the surface of Ni–Si3N4 composite coating are compact. The crystallite structure was face centred cubic (fcc) for electrodeposited nickel and Ni–Si3N4 nanocomposite coatings. The micro hardness of the composite coatings (720 HV) was higher than that of pure nickel (310 HV) due to dispersion-strengthening and matrix grain refining and increased with the increase of incorporated Si3N4 particle content. The corrosion potential (E corr) in the case of Ni–Si3N4 nanocomposite had shown a negative shift, confirming the cathodic protective nature of the coating.

Fatigue Behavior of Ni-P Coated Si3N4 Reinforced Al6061 Composites

Ni–P coated Si3N4 reinforced Al6061 composites were fabricated by stir casting technique. Silicon nitride particles were varied in steps of 2 from 6wt.% to 10wt.%. Cast matrix alloy and developed composites were hot forged at a temperature of 500̊C using a 300T hydraulic hammer. Both as cast, hot forged matrix alloy and its composites were subjected to microstructural studies and fatigue strength tests. Microstructural studies reveal even distribution of silicon nitride particles with excellent bond between the matrix and reinforcement in both as cast and hot forged condition. It is observed that, increased content of reinforcement in both as cast and hot forged composites do result in significant improvement in fatigue strength. However, when compared with as cast matrix alloy and its composites, hot forged alloy and its composites exhibit higher fatigue strength. Both as cast and hot forged composites demonstrate improved fatigue strength when compared with the unreinforced alloys under identical test conditions. Fractured surfaces were examined using scanning electron microscopy (SEM) for the possible fracture mechanisms.

Influence of SiC/Si3N4 Hybrid Nanoparticles on Polymer Tensile Properties

Nanostructured silicon carbide (SiC)/silicon nitride (Si3N4) hybrid nanoparticles exhibit a high-potential for reinforcement of polymers. In the present investigation, silicon carbide (β-SiC) nanoparticles (~30 nm) were sonochemically coated on acicular silicon nitride (~100 nm × 800 nm) particles to increase the thermal and mechanical properties of Nylon-6 nanocomposite fibers. To produce Nylon-6/(SiC/Si3N4) nanocomposite fibers, we have followed a two-step process. In the first step, SiC nanoparticles were coated on Si3N4 nanorods using a sonochemical method and Cetyltrimethylammonium Bromide surfactant. In the second step, the SiC coated Si3N4 hybrid nanoparticles were blended with Nylon-6 polymer and extruded in the form of nanocomposite polymer fibers. The nanocomposite fibers were uniformly stretched and stabilized using a two-set Godet roll machine. The diameters of the extruded neat Nylon-6 and SiC/Si3N4/Nylon-6 nanocomposite fibers were measured using a scanning electron microscope and then tested for their tensile and thermal properties. These results were compared with the neat Nylon-6 polymer fibers. These results clearly indicate that the as-prepared nanocomposite polymer fibers are much higher in tensile strength (242%) and Young’s modulus (716%) as compared to the neat polymer fibers.

Preparation and Characterization of Al-Si<sub>3</sub>N<sub>4</sub> Composite Particles

Fine Al-Si3N4 composite particles were prepared via mechanochemical processing of the coarse aluminum powder and submicron silicon nitride powder in order to obtain the core-shell structure of composite powder particles. It was expected that soft aluminum particles could form a thin coat on hard silicon nitride particles. The resultant particles were characterized through scanning and transmission electron microscopy and electron spectroscopes. Their particle size distribution, specific surface area, nitrogen/oxygen content and phase composition were also determined. Chemical analysis showed that limited oxidation occurred during mechanochemical processing. It has been found that a thin Al-enriched layer (larger than 10 nm) formed at some Si3N4 particles apart from the opposite effect if Si3N4 particles were occluded in coarser Al items. Discussion of the results is also presented.

Microstructure of Short Carbon Fiber/Si<sub>3</sub>N<sub>4</sub>-Reinforced BAS Glass-Ceramic Matrix Composites

Compact short carbon fiber and silicon nitride particles co-reinforced BAS (barium-aluminosilicate) composites were synthesized by hot-pressed. Phase compositions and microstructures of these composites were characterized by means of XRD and SEM methods. The results showed that BAS was benefit to the densification and partially realize the αβ-Si3N4phase transformation. Definite orientation of the carbon short fibers was observed in the BAS matrix.

Room-temperature ferromagnetism in silicon oxide/silicon nitride composite films

Room-temperature ferromagnetism has been observed in silicon oxide/silicon nitride composite films formed on Si substrates at different substrate temperatures, and the ferromagnetic properties of the samples have been found to depend on the silicon nitride content of the films. It is proposed that the ferromagnetism is related to the interface states between the silicon oxide particles and silicon nitride particles. The saturation magnetization (MS) reached its maximum value in the film produced at a substrate temperature of 400 °C. A further study on the magnetic properties of the film has been carried out using first-principles calculations based on the density functional theory. The calculations suggest that the magnetic moments of the film originate from N 2p and Si 2p states in the vicinity of the hetoro-interface.

Application of Mechanochemical Processing for Preparation of Si3N4-based Powder Mixtures

Mechanochemical processing (MCP) involves several high-energy collisons of powder particles with the milling media and results in the increased reactivity/sinterability of powder. The present paper shows results of mechanochemical processing (MCP) of silicon nitride powder mixture with the relevant sintering additives. The effects of MCP were studied by structural changes of powder particles themselves as well as by the resulting sintering/densification ability. It has been found that MCP significantly enhances reactivity and sinterability of the resultant material: silicon nitride ceramics could be pressureless sintered at 1500 o C. Nevertheless, a degree of a silicon nitride crystal lattice and powder particle destruction (amorphization) as detected by XRD studies, is limited by the specific threshold. If that value is crossed then particle's surface damage effects are prevailing thus severe evaporation overdominates mass transport at elevated temperature. It is discussed that the cross-solid interaction between particles of various chemical composition, triggered by many different factors during mechanochemical processing, including a short-range diffusion in silicon nitride particles after collisions with other types of particles plays more important role in enhanced reactivity of tested compositions than amorphization of the crystal lattice itself. Controlled deagglomeration of Si3N4 particles during the course of high-energy milling was also considered.

Adhesion of Contaminant Particles to Advanced Photomask Materials

A challenge to the use of extreme ultraviolet lithography (EUVL) is contamination of the mask during its processing and storage since current techniques for contamination prevention, such as pellicles, cannot be used with the mask materials under EUVL conditions. This paper characterizes the adhesion forces between model contaminant particles and photomask and thin film surfaces relevant to extreme ultraviolet and deep ultraviolet lithography. Specifically, experimental studies of the adhesion of nanoscale and microscale silica and silicon nitride particles to surfaces such as chromium oxynitride, quartz, MoSi, tantalum oxynitride, and ruthenium in air are described. In addition, an adhesion force mapping scheme, the “force band diagram,” is presented. This method allows upper and lower limits to be imposed on the adhesion force between given particle-substrate pairs. Two extremes of behavior are considered in the force bands, a rough prolate spheroid (minimum adhesion force) and a smooth oblate spheroid (maximum adhesion force). Experimental data are compared with the force band models and in all cases the measured adhesion forces fall within the established boundaries for particle sizes ranging from the nanoscale to the microscale. This technique is general, and can be applied to other surfaces of interest to the microelectronics manufacturing community.

Co-electrodeposition and characterization of Cu–Si3N4 composite coatings

Smooth copper coatings containing well-distributed silicon nitride particles were obtained by co-electrodeposition in acidic sulfate bath. The cathodic current density did not show significant influence on incorporated particle volume fraction, whereas the increase of particle concentration in the bath led to its decrease. The increase of stirring rate increased the amount of embedded particles. The microhardness of the composite layers was higher than that of pure copper deposits obtained under the same conditions due to dispersion-strengthening and copper matrix grain refinement and increased with the increase of incorporated particle volume fraction. The microhardness of composites also increased with the increase of current density due to copper matrix grain refining. The composite coatings presented higher strength but lower ductility than pure copper layers. Pure copper and composite coatings showed the same corrosion resistance in 0.5wt.% H2SO4 solution at room temperature.

Toughening in Graphene Ceramic Composites

The majority of work in graphene nanocomposites has focused on polymer matrices. Here we report for the first time the use of graphene to enhance the toughness of bulk silicon nitride ceramics. Ceramics are ideally suited for high-temperature applications but suffer from poor toughness. Our approach uses graphene platelets (GPL) that are homogeneously dispersed with silicon nitride particles and densified, at ∼1650 °C, using spark plasma sintering. The sintering parameters are selected to enable the GPL to survive the harsh processing environment, as confirmed by Raman spectroscopy. We find that the ceramic's fracture toughness increases by up to ∼235% (from ∼2.8 to ∼6.6 MPa·m(1/2)) at ∼1.5% GPL volume fraction. Most interestingly, novel toughening mechanisms were observed that show GPL wrapping and anchoring themselves around individual ceramic grains to resist sheet pullout. The resulting cage-like graphene structures that encapsulate the individual grains were observed to deflect propagating cracks in not just two but three dimensions.

Abrasive wear behavior of Ni–P coated Si 3N 4 reinforced Al6061 composites

Ni–P coated Si 3N 4 reinforced Al6061 composites were fabricated by vortex method. Percentage of reinforcement was varied from 6 wt.% to 10 wt.% in steps of 2. Cast matrix alloy and developed composites were hot forged at a temperature of 500 °C using a 300T hydraulic hammer. Both as cast and hot forged matrix alloy and its composites were subjected to microstructure studies, grain size analysis, microhardness and abrasive wear tests. Microstructure studies reveal uniform distribution of silicon nitride particles with good bond between matrix and reinforcement in both as cast and hot forged condition. It is observed that, increased content of reinforcement in both as cast and hot forged composites do result in significant grain refinement. However, when compared with as cast matrix alloy and its composites hot forged alloy and its composites exhibits higher extent of grain refinement. Both as cast and hot forged composites exhibit improved microhardness and abrasive wear resistance when compared with the unreinforced alloys under identical test conditions. Abraded worn surfaces were examined using scanning electron microscopy (SEM) for possible wear mechanisms. Increased abrasive particle size and load has resulted in larger extent of grooving leading to increased abrasive wear loss for both the matrix alloy and developed composites.