Powder Processing Parameters Research Articles

SELECTING OPTIMAL PROCESS PARAMETERS OF Al2O3/C COMPOSITE USING GRA WITH PCA AND TAGUCHI’S QLF APPROACH

The aim of this study is to find the controlled factors affecting the mass density of the combined Al2O3/Cu. All experiments were carried out using powder metallurgy. Experiments were carried out with four controllable powder processing parameters, namely milling time, compaction pressure, sintering temperature, and holding time. The L18 mixed-level Taguchi Orthogonal Array was used for experimental because it is the basis for the analysis of the Taguchi method. In this research, statistical analysis is carried out using GRA with PCA and Quality Loss Function. The result was the best model based on the Quality Loss Function, because the method has the biggest determination coefficient value is 99,97% where the results is better than GRA with PCA. From the main effect table study, the optimal combination of parameters for response: mass density and hardness are A2B3C3D2 powder metallurgical process parameters, namely milling time of 360 minutes, compacting powder of 200 MPa, sintering of 7000C, and holding time of 20 minutes. The ANOVA results show that the compaction pressure has the most influential parameter that affects the response. The percentage contribution of compaction pressure is 87.09%. Based on ANOVA, the R-squared value is 99.97%, which means the tested factor variables can explain the density of the Al2O3/Cu composite by 99.70%. Therefore, only 18 experimental trials are needed to discover the reality of what will happen in the process.

Synthesis and electrochemical behaviour of TiC- and B4C-reinforced Al-based metal matrix composite

Aluminium (Al)-based metal matrix composites were developed with titanium carbide (TiC) and boron carbide (B4C) materials as reinforcement. The weight percentages of titanium carbide (1.5%) and boron carbide (0.5%) powder were maintained throughout the process of composite development. Composite process parameters such as powder compaction pressure, sintering temperature and time were varied in different combinations. The prepared composites were mechanically evaluated and metallurgically investigated for their quality. Further, the samples were subjected to electrochemical analysis to study their behaviour in 3.5% sodium chloride (NaCl) solution. From the experimentation, the corrosion potential and current density were measured. Subsequently, the corrosion rate (mm/year) of the material was calculated through its Tafel plot. The composite processed at a sintering temperature of 630°C for a duration of 135 min had higher corrosion resistance, with a minimum corrosion rate of 1.699 mm/year. The electrical resistance also increased over the exposed surface with a minimum current density of 0.15 mA/cm2. Scanning electron microscopy and energy-dispersive spectroscopy (EDS) were used to determine the metallurgical quality of the exposed surface. The oxide formation was observed on the exposed surface in the process of corrosion. The element aluminium and oxygen were found on the surface which denotes that the Aluminium oxide formed on the exposed surface. From the results, a discussion is presented confirming the influence of composite powder processing parameters.

Design and optimization of NiMg/ceria-zirconia catalyst pellets

Mechanical strength plays a significant role in the industrial applications of the solid catalysts. Often powder catalysts must be “formed” into pellets to meet pressure drop restrictions in packed tubular reactors. The pellets must be designed to be mechanically stable when subjected to thermal and mechanical stresses during operation. The objective of this study was to evaluate the effect of powder processing parameters on mechanical stability of the resulting extruded cylindrical NiMg/Ce0.6Zr0.4O2 pellet catalysts. The binder amount, water amount, and pH of solvent impacted physicochemical properties and mechanical strength of the catalysts. Optimal amounts of binder and water, as well as a low slurry pH can increase the crush strength and breakage resistance. An enhancement in mechanical strength of 220% was obtained by optimizing the binder to solvent ratio and pH conditions. The tri-reforming performance (e.g., CH4 and CO2 conversions, and H2/CO molar ratio) was minimally impacted when the powder processing was optimized to improve mechanical strength.

Optimization of powder metallurgy processing parameters of Al2O3/Cu composite through Taguchi method with Grey relational analysis

This article investigates the effect of powder metallurgy processing parameters on multi-responses: mass density and hardness of Al2O3/Cu composite based on Taguchi method coupled with Grey relational analysis. Based on Taguchi’s L18 orthogonal array, the experimental trial runs were conducted with four controllable powder processing parameters: milling time, compaction pressure, sintering temperature and holding time. The Grey relational analysis (GRA) was performed to find the optimal powder processing condition with Grey relational grade (GRG) as a measure of performance index. Analysis of variance (ANOVA), 3D surface plots and contour plots were used to express the most influential parameter that affects mass density and hardness of Al2O3/Cu composite. Confirmation tests were conducted to make sure the validity of test results. The scanning electron microscope (SEM) images show the presence of Al2O3 particle in the composite. The Energy Dispersive X-Ray (EDX) spectrum indicates the presence of chemical elements: Cu, Al, O in the composite. The results show that the optimal powder metallurgy parameter combination is A2B3C3D1. The mean Grey relational coefficient (GRC) analysis shows that the mass density was more easily influenced by factors considered compare to hardness. The mean GRG result shows that the compaction pressure has the strongest correlation to responses. The result of 3D surface plots, contour plots and ANOVA indicate that the compaction pressure has most influential parameter that affect GRG. The % contribution of parameters shows that the % contribution of compaction pressure is significant (80.22%) compare to other main effects and interaction effects. The confirmation tests revealed that the performance characteristic of Al2O3/Cu composite was improved by GRA based Taguchi technique. The Monte Carlo simulated model summery show that based on Taguchi L18 Orthogonal Array design, one can easily find the reality of what will be happening in a process. Therefore, optimization of processes parameter could be simplified by using the Grey-based Taguchi method.

Metal matrix to ceramic matrix transition via feedstock processing of SPS titanium composites alloyed with high silicone content

Titanium silicides are promising candidates for use as a reinforcement in advanced light-weight composites due to their excellent mechanical properties and oxidation resistance at high temperatures, sufficient wear resistance, and high chemical stability in various corrosion environments. Direct in-situ synthesis of such composites from titanium-silicon (Ti-Si) powder feedstock by spark plasma sintering (SPS) was used in this study with a particular attention on the effect of the powder processing parameters (blending, co-milling, milling + blending) on the microstructure formation and mechanical properties of the sintered composites. As opposed to the previous silicide-reinforced Ti studies, this was done for high silicone content (20 wt%). It was found that, despite the powders initial identical composition, the microstructure and phase content of the compacts varied significantly with the used powder fabrication route. Taking advantage of this, composites ranging from relatively soft metal-matrix (52 vol% metallic Ti; using non-milled Ti and coarse or fine-milled Si) to hard ceramic-matrix (11 vol% metallic Ti, using fine-dispersed joint-milled mixture of Ti and Si) were obtained. Due to in-situ formation of various TiSi2, TiSi, Ti5Si4 and Ti5Si3 silicide reinforcement phases contents with high hardness and stiffness, all the sintered composites showed superior hardness and wear resistance (an increase as much as 44×) in comparison to pure Ti. Importantly, hardness and elastic modulus of intermediate compounds TiSi2, TiSi, Ti5Si4 and Ti5Si3 were measured using instrumented indentation technique for the first time and are presented in the paper.

The Influences of Powder Processing Variables on the Properties of Bi-2223/Ag Tapes

High-temperature superconducting (HTS) (Bi, Pb) <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Sr <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Ca <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> Cu <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">10</sub> /Ag superconducting tape (Bi-2223 tape) is made mainly by three process steps including preparation of precursor powder, mechanical deformation, and heat treatment of the tape. Recently, our main efforts have been made to improve the precursor powder. With nitrates and nitric acid as main starting materials, and using spray drying and other technology, an effective process of making precursor powder for Bi-2223 tape has been developed. This paper reports this process in detail and the influences of powder processing parameters on the tape properties, such as aliquation of composition, particle size, as well as residual oxynitride, carbon, and water. By optimizing powder preparation parameters, high-quality Bi-2223 tape with critical current of about 150 A (77 K, self field) was made.

Utilizing microwaves for the determination of moisture content independent of density

Abstract Bulk density and moisture content are both very important powder-processing parameters that affect, among other things, the material's flowability and compressibility, as well as the final product's quality. Many traditional microwave methods to determine these parameters rely on the calculation of the real (e′) and imaginary (e″) components of the sample's relative complex permittivity. These parameters can also be calculated directly from raw sensor measurements. Using the conductance and frequency at resonance of an open-reflection microwave resonance sensor allowed the determination of a sample's moisture content (MC) with a high degree of accuracy. The method was applied to static samples of microcrystalline cellulose (MC range 0.568–6.163% and density range 0.280–0.499 g/cm3) and α-lactose monohydrate (MC range 5.59–8.69% and density range 0.346–0.691 g/cm3). The results indicated that the described method predicts moisture content accurately and independent of density fluctuations. As a result, the described method has been shown to be a viable alternative to other established microwave moisture content calibrations.

Characterization of dry milled powders of LAST (lead–antimony–silver–tellurium) thermoelectric material

Although thermoelectric (TE) materials are often fabricated as cast ingots, there has been recent interest in the powder processing of these materials. Cast TE materials typically have grain sizes as large as several hundred microns, but powder processing (grinding, milling and then sintering) can produce dense specimens with a reduced grain size, an improved mechanical integrity and enhanced TE properties. In the TE literature when powder processing is employed, little or no description is provided of the powder processing techniques and the powder processing parameters are either not characterized or only a mean particle size is given. In this study, powders milled from solid cast ingots of the TE compound LAST (lead–antimony–silver–tellurium) were characterized via Coulter Counter, to measure the mean powder particle size and the size distribution, scanning electron microscopy (SEM), to examine the powder particle morphology, and X-ray diffraction (XRD), to detect possible phase changes or amorphization. The impurity levels in the milled powders were examined by wear rate measurements on the milling media, as well as by energy dispersive X-ray analysis and inductively coupled plasma measurements.

Processing of porcelain enamel glass powders for electrostatic spraying

Following a brief review on current technology of electrostatic spray for enameling, the requirements on powder properties were discussed. The use of poly (siloxanes) or poly (silanes) as encapsulants for producing electrostatic porcelain enamel powders with appropriate electrical resistivity, hydrophobicity and fluidity was analyzed from a mechanistic standpoint. Experimental results were presented to illustrate typical processing problems such as the change of powder properties on aging as a result of differential encapsulation of glass components. Various measures were proposed for improving the stability of powder properties. Optimization of powder processing parameters by means of Taguchi experimental design technique was described.

Kinetics and mechanism of the (B1,Pb)2Sr2Ca2Cu3O10 formation reaction in silver-sheathed pires

Abstract A detailed kinetic and mechanistic analysis of the growth of the (Bi 2− x Pb x )Sr 2 Ca 2 Cu 3 O 10 phase in silver-sheathed wires has been performed by an isothermal equilibration method. Silver tubes loaded with precursor powders were processed into wires using established metallurgical techniques. The wire specimens were immersed in a preheated equilibration apparatus, heat-treated at the desired temperature in 7.5% O 2 , for varying periods of time, then quenched in a room-temperature silicone oil bath. The results indicated that the kinetic data followed a nucleation growth mode1 derived for a reaction at the interface between thin sheets and a fine powder or a fluid. Transmission electron microscopy confirmed the two-dimensional reaction geometry and revealed the presence of an amorphous phase at grain boundaries, where rapid transport diffusion appears to occur due to the absence of the stabilizing influence of the regular lattice. A reduction in activation energy was observed at temperatures 2819°C which is tentatively attributed to the onset of a liquid-phase-controlled reaction (i.e. a phase boundary crossing). The effects of powder processing parameters and precursor particle size on the kinetic behavior and the growth rate of the (Bi 2− Pb x )Sr 2 Ca 2 Cu 3 O 10 phase are also discussed.