Effect Of Powder Particle Size Research Articles

Effect of Powder Particle Size on Microstructure and Mechanical Properties of Cold-Sprayed Pure Nickel Coatings

Effect of Powder Particle Size on Microstructure and Mechanical Properties of Cold-Sprayed Pure Nickel Coatings

Hot oscillatory pressure preparing low-cost FGH4096 superalloys with high performance

The low-cost and high-performance FGH4096 superalloy was prepared by replacing the high-cost fine powder particles (<51 μm) with coarse particles (>120 μm) using the hot oscillatory pressure (HOP) sintering method. The effects of powder particle size on the grain size and mechanical properties of the superalloy were investigated. The results showed that the tensile strength is 1350 MPa and the elongation is 30.4% for the HOP samples of coarse powder, the mechanical properties are higher than that of the samples prepared by the hot-press (HP) with finer powder. In addition, HOP sintering shows good inhibitory effect for the prior particle boundaries (PPB) in the powder metallurgy superalloys, for the HOP sintering providing the great driving force of particles plastic deformation. The results suggest that the coarse powder particle size with HOP sintering can achieve the better mechanical properties for the FGH4096 superalloys, thus provides a strategy for the low-cost and high-performance powder metallurgy superalloys.

In situ synchrotron study of sintering of gas-atomized Ti-6Al-4 V powders using concomitant micro-tomography and X-ray diffraction: Effect of particle size and interstitials on densification and phase transformation kinetics

Compared to the well-established powder bed fusion techniques, sinter-based additive manufacturing of titanium alloys remains extremely challenging. This technique involves three steps: (i) shaping of a part composed of metallic powders bound with polymeric binder (ii) debinding (iii) sintering. One main issue is that densification during the solid sintering is promoted by small powder particles whereas the latter have a high propensity to carbon and oxygen uptakes from the binder, which are detrimental to ductility of titanium parts. In this article, we report a unique in-depth characterization of solid sintering of titanium powders using in situ coupled micro-computed tomography (µCT) and X-Ray diffraction under synchrotron radiation at high temperature, combined with in situ environmental scanning electron microscopy (HT-eSEM). Evolution of global porosity, pore size distribution and interconnectivity as well as allotropic titanium phase transformation and precipitation of second-phase precipitates (titanium carbides) were determined, allowing a discussion on the densification/phase transformation relationship. This multi-scale in situ study of solid sintering was used to identify the effect of powder particle size on the contamination / densification trade-off. Carbon/oxygen uptakes clearly increase the α-to-β transus but do not affect significantly the final porosity of the sintered parts, which argues for a secondary role of the β phase on the sintering kinetics of titanium alloys. Reducing the powder particle size has a tremendous effect on both the densification kinetics and the final pores structure.

Cracking Behavior of Atmospheric Plasma-Sprayed 8YSZ Thermal Barrier Coatings during Thermal Shock Test

The failure of plasma-sprayed thermal barrier coatings (TBCs) during service is usually related to the cracking behavior. In this study, plasma-sprayed TBCs were prepared with two kinds of agglomerated sintered yttria-stabilized zirconia (YSZ) powders with different particle sizes. The evolution of mechanical properties and crack propagation behavior of the coatings during the whole life stage were studied by a thermal shock test. The effect of powder particle size on the cracking behavior of the TBCs during thermal shock was analyzed from the aspect of pore structure, mechanical properties, and stress state of the coatings. The crack propagation and coalescence in the direction parallel to the substrate in the coating is the main factor leading to the spalling failure of the coating during thermal shock. Although the coating prepared by fine YSZ has higher fracture toughness, the lower strain tolerance will increase the cracking driving force on the crack tip of the coating during thermal shock, and the cracks in the coating propagate merge at a faster rate during thermal shock. The larger porosity and pore size of the coating prepared by coarse YSZ help the coating suffer less thermal stress during thermal shock. Although the existence of pores reduces the fracture toughness of the coating to a certain extent, the increase of strain tolerance reduces the crack growth rate in the coating, so the coating has a longer life.

The effect of powder particle size on the corrosion behavior of atmospheric plasma spray-Y2O3 coating: Unraveling the corrosion mechanism by fluorine-based plasma

The atmospheric plasma spray (APS) -Y2O3 coatings are widely used to minimize damage to internal parts of the chamber caused by the strong corrosive effect of fluorine-based plasma used in dry etching; however, the poor density of APS-Y2O3 coatings results in low plasma corrosion resistance. This is a major cause of the generation of contamination particles during CF4/O2 plasma etching. Hence, defects inside the coating must be eliminated to improve the plasma corrosion resistance of APS-Y2O3 coatings.The correlation between the decrease in the number of defects inside the APS-Y2O3 coatings according to the powder particle size and the surface corrosion process by CF4/O2 plasma etching was confirmed. We verified that the internal defects in APS-Y2O3 coatings can be controlled with small powder particles because the powder particles in the APS layer melt efficiently under the APS coating conditions; in addition, the fluorine content rate inside the coating is improved. After the focused ion beam (FIB) process, by examining YOxFy layer with a field emission scanning electron microscope (FE-SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray photoelectron spectroscopy (XPS); we observed the formation of a thick YOxFy layer with decreasing number of defects inside the APS-Y2O3 coatings; thereby, the bonding strength among the Y2O3 powder particles was increased, and corrosion of YOxFy layer due to physical and chemical reactions decreased; as a result, the etch amount was significantly reduced.Therefore, it can be seen that the generation of contamination particles in the CF4/O2 plasma etching can be reduced by controlling the occurrence of defects inside the APS-Y2O3 coatings. The results of this study demonstrate the possibility of minimizing the effect of contamination particles generated in the dry etching process to remove YOxFy layer using chamber self-cleaning such as waferless step. This paper presents a new direction for controlling contamination particles in the inner coating parts of the plasma etching chamber.

Effect of Powder Particle Size and Shape on Appearance and Performance of Titanium Coatings Prepared on Mild Steel by Plasma Cladding

The preparation of Ti coatings on mild steel can both effectively improve the corrosion resistance of the substrate and reduce the application cost of Ti, which is an effective measure to improve the service performance of mild steel in the marine environment. Plasma cladding technology is an efficient method for preparing metal coatings, and the type of powder is a key process parameter for coating preparation. In this work, high-performance Ti coatings are prepared on the surface of mild steel by plasma cladding technology, and the effects of different particle sizes and shapes of Ti powders on the surface morphology, microstructure and properties of the coatings are studied. The results show that powder particle size and sphericity are the key factors affecting the morphology, structure and service performance of Ti coatings. After 1000 h of salt spray test, the spherical powder cladding coatings only suffer slight corrosion, while the irregular shape powder coating is more severely corroded. Powder cladding with moderate powder particle size and good sphericity have a smoother coating and fewer defects. Ti powders with different particle sizes and shapes all have the diffusion of Fe element during the cladding process. The surface of Ti coating prepared by spherical powder are dominated by α-Ti and Fe0.2Ti0.8 phases, while the surface of Ti coating prepared by irregular shape powder is dominated by FeTi and Ti2Fe. The interface between the coating and the substrate shows metallurgical bonding, and the increase in Ti-Fe brittle phase will deteriorate the mechanical properties and corrosion resistance of the coating. The shear strength of coatings prepared from spherical Ti powders of 75–150 μm can reach 105.18 MPa, the corrosion potential is the most positive (−0.2206 V), and the self-corrosion current density is the lowest (6.220 × 10−8 A/cm2).

Valorization of asparagus-leaf by-product through nutritionally enriched chips to evaluate the effect of powder particle size on functional properties and rutin contents

This study first observed that the nutritional and phytochemical contents in asparagus leafy by-product were comparable or higher than those in edible portion. The extractable rutin in leaf was found to increase with a decrease in powder particle size (400–120 μm), as indicated by ultra-performance liquid chromatographic analysis. Then, such leaf powders of different particle sizes were incorporated into freeze-dried chips formulation to evaluate the effect on chips properties. There was an apparent higher retention of total chlorophylls (161%), total phenolic (46%), and total flavonoid (79%) due to the decrease in particle size, ultimately showing an increase in the antioxidant activities. Also, the color (L*, a*, and b* values) was significantly difference (p < 0.05). LF-NMR study indicated the status of water and safer level of drying (a w = 0.6). Conclusively, samples containing finer asparagus powder showed higher nutritional and phytochemical contents than those made with coarser powder.

Investigation on the effect of powder size on the properties of cladding layer based on RSM

This paper aims to reveal the influence of different TiC powder particle sizes and process parameters on the cladding morphology of composite materials and realize the forming control of cladding layer. The center composite design of response surface method was adopted to analyze the effects of laser power, scanning speed and particle size on the cladding morphology of composite materials. The mathematical models between process parameters, TiC powder particle size and micro-hardness, wear volume of the composite cladding layer were established and confirmed by variance analysis and model verification. The results indicate that powder particle size has most significant effect on the micro-hardness, and it increase with the increase of scanning speed, laser power and powder particle size; the effect of powder particle size on the wear resistance of the clad layer is most significant, and it increases with the increase of powder particle size and decreases with the increase of scanning speed and laser power. The optimization of process parameters is carried out with the target of maximizing micro-hardness and minimizing wear area. The error rates between prediction and experiment for the micro-hardness and wear area are 0.1% and 2.0% respectively. The results of this paper provide a reference for the prediction and control of the cladding morphology of composite materials.

The Effect of Powder Particle Size on the Corrosion Behavior of Atmospheric Plasma Spray-Y2o3 Coating: Unraveling the Corrosion Mechanism by Fluorine-Based Plasma

The Effect of Powder Particle Size on the Corrosion Behavior of Atmospheric Plasma Spray-Y2o3 Coating: Unraveling the Corrosion Mechanism by Fluorine-Based Plasma

Effects of Powder Particle Size on Fatigue Performance of Laser Powder-Bed Fused Ti-6Al-4V

In powder-based metal additive manufacturing, one key specification that needs to be precisely optimized is the particle shape and size distribution of metallic powders. Particle shape and size distribution influences the flowability of the powder and the uniformity of powder bed density (i.e. packing state of the powder). These eventually affect the porosity, which ultimately influences the fatigue performance of the fabricated parts. Therefore, it is essential to understand the effect of powder characteristics on the fatigue behavior before additively manufactured parts can be used in load-bearing, safety-critical applications. The current study aims at assessing the effects of powder particle size and morphology on mechanical properties and fatigue response of laser beam powder bed fused (LB-PBF) Ti-6Al-4V; an alpha-beta workhorse alloy of the titanium family. Several Ti-6Al-4V powder batches with different size distributions are used to fabricate the parts employing an EOS M290 machine. Powder characteristics, including flowability, compressibility, cohesion, size, and shape morphology, are investigated to reveal the differences between the two tested powder batches. Porosity levels and mechanical testing results are compared among specimens fabricated from different powder batches and the differences are explained based on variations in powder characteristics.

Effect of powder particle size on performances of SiC ceramic balls

The silicon carbide ceramic balls were prepared with different mean particle sizes of 0.5μm and 1.0μm. The powder particle size’s impacts on sintering density, crushing load ratio, hardness, fracture toughness, surface quality and microstructure of ceramic balls were investigated. The results show that the hardness and sintering density with different powder particle sizes were similar. Ceramic balls prepared with finer powder whose mean particle sizes 0.5μm are observed with better mechanical properties and structural homogeneity. The sintering density of ceramic balls with mean particle sizes 0.5μm is 3.118g/cm3, the average of Vickers hardness, average crushing load ratio and fracture toughness is HV2125, 60.6% and 3.22MPa/m1/2.

Plasma-sprayed lanthanum-doped strontium titanate as an interconnect for solid oxide fuel cells: Effects of powder size and process conditions

As a key component of the novel bi-layer interconnect for solid oxide fuel cells (SOFC), La-doped SrTiO3 (LST) has been deposited by atmospheric plasma spraying in this study. The effects of powder particle size, hydrogen flow rate and deposition temperature on stoichiometry, microstructure, and properties of LST deposits have been systematically investigated. The preferential vaporization loss of Sr is quantified by the relationship between the droplet size and splat composition, while the droplet size prior to impact is measured by a confocal laser microscopy and the composition of splat is analyzed by the energy-dispersive spectrum of scanning electron microscopy. Thermogravimetric analysis is used to determine the oxygen non-stoichiometry of the deposit. It is found that when the droplet diameter is smaller than 30 µm, the preferential vaporization induced Sr loss is significantly increased up to 45% with decreasing particle size, while it is greatly reduced if the droplet size is larger than 30 µm. Two mechanisms including diffusion-dominated mass transfer and convection-dominated mass transfer are proposed to explain the particle size effect on Sr loss. With increasing H2 flow in plasma gas, the oxygen deficiency in LST deposit is increased. Moreover, the effective bonding at lamellar interfaces is realized by increasing the deposition temperature to higher than the critical bonding temperature. The electrical conductivity of LST deposits is remarkably improved by decreasing Sr loss, increasing oxygen vacancy concentration, and enhancing the lamellar bonding. The LST coatings prepared at a deposition temperature of 450°C with coarse powder particles exhibits a dense microstructure and a conductivity of ~100 S/cm at 850°C in the reducing atmosphere. The results show that by properly optimizing the process conditions, the plasma-sprayed LST coating is a promising candidate to be a part of the bi-layer interconnect for SOFCs.

On the Characteristics of Cold Spray Technology and Its Application in Aerospace Industries

Cold spraying technology is an advanced spraying technology developed based on the principles of aerodynamics. It is mainly used to deposit and repair the surface of metal alloy parts to ensure that the parts have better mechanical properties and service life. Compared with traditional thermal spraying technology, cold spraying technology has many advantages, such as low spraying temperature, low oxygen content and low porosity, and it is not easy to cause oxidation, burning, phase change and other phenomena during spraying. This article reviews the principles, technical parameters, and characteristics of cold spray technology, focusing on the effects of powder particle size and shape, particle and substrate temperature, critical speed, spray gun, collision angle, and spray distance on coating quality and deposition efficiency. In addition, the current research and application status of cold spray technology in the preparation of anti-corrosion coatings, high temperature resistant coatings, high temperature oxidation and wear resistant coatings are discussed, and the development prospects of cold spray technology are prospected.

Influence of Nickel Powder Particle Size on the Microstructure and Densification of Spark Plasma Sintered Nickel-Based Superalloy

This study aims to investigate the effects of powder particle size on the densification and microhardness properties of spark plasma sintered superalloy. Three particles size ranges of nickel were used in this study, namely, (3-44, 45-106 and 106-150 μm), and this is the matrix in the IN738LC superalloy composition (powder), used in the study. The effects of the particle size were examined at a specific applied temperature and pressure. The transitioning stages during the sintering process of the green powders to the formation of the sintered alloy were analyzed and given as the particle rearrangement stage, the localized deformation stage and the neck formation/grain growth stage. There was the formation of γ, γ' and a solid solution within the microstructure of the sintered alloys. The effect of particle size was more pronounced on the grain sizes obtained, while the phases formed is the same for the three alloys. The results indicate that the nickel particle size (&gt;60% of the total composition) has a significant influence on the densification, porosity, grain size and hardness properties of the IN738LC sintered alloy. Finer nickel particle size resulted in a sintered product with smaller grain size (9 µm), reduced percentage porosity (3.9%), increased relative density (96.1%) and increased hardness properties (371 Hv).

Effect of inorganic powder hydrated lime on performance of asphalt mortar at medium, high, and low temperature

This paper investigated the effects of the grain diameter of inorganic powder particle hydrated lime and the aging of asphalt on the properties of asphalt mortar. The Dynamic Shear Rheological Test, Multiple Stress Creep Recovery Test, and Bending Beam Rheological Test were applied to evaluate the effects of powder particle size and asphalt aging on medium-temperature, high-temperature creep performance, and low-temperature crack resistance of mortar. The experimental results demonstrated that the anti-fatigue performance of unaged and aged mortar increased as filler particle size decreases. Meanwhile, asphalt aging was beneficial to the fatigue performance of asphalt mortar, especially for the fine filler particles (M3). However, with the decrease of particle size and an increase in structural asphalt adsorbed in the mortar, the high-temperature performance of aged and unaged mortar gradually become worse. In addition, with a decrease in particle size and an increase in specific surface area, adsorption of more asphalt reduced the mortar modulus and increased the viscosity. This counterbalanced the deleterious effect on the low-temperature performance of the asphalt mortar. Finally, it was found that the microscopic morphology of aged asphalt mortar, compared with the microstructure of unaged asphalt mortar, presented transition from smooth surface to fold texture, and the fillers of coarse particles of aged asphalt mortar were unevenly distributed.

Effect of Powder Particle Size and Spray Parameters on the Ni/Al Reaction During Plasma Spraying of Ni-Al Composite Powders.

It was known for long that Ni-Al composite powders can be used to deposit self-bonding coating as a bond coat for common ceramic coatings due to the exothermic reaction between Ni and Al. However, it was found that with commercial Ni-Al composite powders with a large particle size, it is difficult to ignite the self-propagating reaction between Ni and Al to form Ni-Al intermetallics by plasma spraying. In this study, Ni-Al composite powder particles of different sizes were used to prepare Ni-Al intermetallics-based coatings by plasma spraying. The dependencies of the exothermic reaction between Ni and Al and the coating microstructure on powder particle size and spray parameters were investigated. The phase composition, microstructure, porosity and oxide content of the coatings were characterized by x-ray diffraction, scanning electron microscope and image analyzing. The results show that particle size of Ni-Al composite powders is the dominant factor controlling the exothermic reaction for the formation of Ni-Al intermetallics during plasma spraying. When the powders larger than about 50 μm are used, the reaction forming aluminide cannot complete even by heating of plasma flame generated at high plasma arc power. However, when smaller powders less than 50 μm are used, the exothermic reaction can completely occur rapidly in plasma spraying, contributing to heating of Ni-Al droplets to the highest temperature for development of the self-bonding effect. The positive relationship between molten droplet temperature and tensile adhesive strength of the resultant coatings is recognized to confirm the contribution of high droplet temperature to the adhesive or cohesive strength.

Study on Mechanical Strength Measurement and Strength Improvement of Sulfide-Based Electrodes

The thermal battery is a primary battery that is used in special fields such as defense due to its high power and high reliability characteristics. In the thermal battery, a lithium or lithium compound negative electrode and a metal sulfide-based positive electrode system are used. There is always a demand for reducing the weight of the system and a need for increasing the area of the electrode. Therefore, it is essential to study the mechanical strength of the electrode and improve its strength. In this research, the strength of the compaction of the positive electrode material was quantitatively measured, and research was conducted to improve the strength for weight reduction and large area. Two methods of measurement were proposed for quantifying the mechanical strength of the electrode of the disk-shaped green compact electrode. The fracture strength of the green compact was measured by the "Monotonic equi-biaxial flexural strength test" method proposed by ASTM C1499-09, and the fracture toughness was measured by the double cantilever beam (DCB) test. In order to improve the mechanical strength, the strength according to the powder particle size and the compression pressure was measured. Higher fracture strength and fracture toughness more than double that of green compacts with reference powder grain size and differentiation smaller than 45μm were measured. The effect of powder particle size and compression pressure on strength was analyzed through powder characterizations and microstructure observations. In addition, actual electrodes were fabricated and the possibility of battery utilization was verified through discharge tests. Figure 1

Experimental investigation and economic analysis of surfactant (Span-20) in powder mixed electrical discharge machining (PMEDM) of AISI D2 hardened steel

Powder mixed EDM (PMEDM) is recognized as an advanced and innovative technique with enhanced performance and limited drawbacks in comparison to conventional EDM method. This study investigates the effect of powder particle size, various powder concentrations (Cp), and surfactant concentrations (Cs) on the performance of EDM. Since the machining characteristics are highly dependent on the dielectric performances, significant attention has been directed to introduce Cr powder and Span-20 surfactant into the dielectric fluid to achieve higher productivity and enhanced surface integrity. The EDM machining was carried out on AISI D2 hardened steel through ´Plug & Plaý dielectric circulating system attached to the main machine in order to evaluate the machining performances (i.e. MRR, EWR, and Ra). Interestingly, machining performance was improved with combination of Cr powder mixed and span-20 surfactant. By comparing the performance of span-20 surfactant and micro-nano chromium, the result within selected parameters shows that the span-20 surfactant and nano-chromium is the better choice for the EDM of AISI D2 hardened steel. In the machinability studies, the EDM machining of AISI D2 hardened steel by using span-20 surfactant and nano-chromium has exhibited the excellent machining performances, which led to 45.08% MRR enhancement and 68.89% Ra enhancement comparing to micro-chromium powder and span-20 surfactant led to 35.28% MRR and 28.96% Ra. Furthermore, cost analysis revealed that the nano-Cr powder size was approximately 4 times more economical than micro-Cr powder in machining of AISI D2 hardened steel, although the price for 1 kg is quite expensive.

Effect of powder particle size on microstructure and properties of low pressure cold sprayed high aluminium bronze coating

AbstrasctHigh-aluminum bronze alloy powder was mixed with 16 wt% Al2O3 powder to prepare low-pressure gas dynamic spray coatings with different sized powder particles. The mechanical properties of coatings were tested and the surface, cross section and stretch section of coatings were observed by scanning electron microscopy. Uniform experiment was performed to analyze the effects of particle size of the high-aluminum bronze and Al2O3 powder on coating performance. Experimental results shows that the degree of deformation of the high-aluminum bronze particle in the coating increased with decreasing particle size in the high-aluminum bronze and Al2O3 in the mixed powder. The degree of deformation of the high-aluminum bronze particle in the coating affected the mechanical properties of the coating showing a linear relationship between powder size and coating performance. When the particle size of Al2O3 and high-aluminum bronze particle ranged between 23–25 μm, the coating has the outstanding mechanical properties.

Magnetic properties of anisotropic bonded NdFeB/SmCo permanent magnets

Anisotropic bonded NdFeB permanent magnets have wide potential applications in the areas such as brushless DC motors, spindle motors, and stepping motors due to their excellent processing property and high magnetic properties. Anisotropic NdFeB bonded magnets prepared by hydrogen-disproportionation–desorption-recombination (HDDR) process have large energy product at room temperature. However, they are not stable at ∼100°C, which is the working temperature of many electric motors. In order to improve their thermal stability, we developed bonded NdFeB/SmCo magnets and investigated the effects of powder particle size and SmCo content on their magnetic properties. We proposed a model to clarify the filling effect of the powder, which played a key role in the enhanced (BH)max when reducing the SmCo particle size. As for the SmCo content, the bonded magnets showed improved (BH)max at 100°C-150°C and thermal stability with the increase of SmCo content. And through adjusting the SmCo content, the remanence temperature coefficient and coercivity temperature coefficient from 25-150°C were able to be regulated in the range of -0.14%/°C to -0.04%/°C and -0.51%/°C to -0.14%/°C, respectively. This work provides a design strategy and a facile route to improve the magnetic properties and thermal stability of the bonded magnets.