Investigation on Feedstock Preparation for Micro-Cemented Carbide Injection Molding

2018 ◽  
Vol 18 (2) ◽  
pp. 96-102
Author(s):  
Abdolali Fayyaz ◽  
Norhamidi Muhamad ◽  
Abu Bakar Sulong
Keyword(s):  
Flow Behavior ◽  
Flow Characteristics ◽  
High Viscosity ◽  
Cemented Carbide ◽  
Solid Loading ◽  
Powder Particle Size ◽  
Powder Particles ◽  
Particle Size And Morphology ◽  
Size And Morphology ◽  
Feedstock Preparation

Abstract This research was focused on mixing of submicron cemented carbide (WC-Co-VC) powder and binder. WC-Co-VC powder particle size and morphology were analyzed by laser diffraction and field emission scanning electron microscopy. The WC-Co-VC powder was kneaded with a paraffin wax based binder system. Based on critical solid loading, the feedstock with different solid loadings between 49 to 51 vol.% was prepared. Finally, the flow behavior of different feedstocks was investigated. Morphology of powder revealed that the particles of powder are slightly agglomerated and irregular in shape. The result of mixing indicted that the torque value increases as the solid loading increase from 49 vol.% to 51 vol.%. The feedstock exhibited homogeneity and the powder particles are homogenously coated with binder. The feedstock with solid loading of 51 vol.% is sensitive to temperature and showed high viscosity values. The feedstock with solid loadings of 49 and 50 vol.% had good compatibility and flow characteristics.

Solution-SBR Powders

1976 ◽  
Vol 49 (1) ◽  
pp. 126-139
Author(s):  
D. N. Schulz ◽  
L. E. Calihan ◽  
D. P. Tate
Keyword(s):  
Powder Particle Size ◽  
Factors Affecting ◽  
Molecular Weights ◽  
Bound Rubber ◽  
Powder Blends ◽  
Powder Particles ◽  
Filler Dispersion ◽  
Particle Size And Morphology ◽  
Size And Morphology ◽  
Powdered Rubber

Abstract This paper describes the advantageous cross-fertilization of solution-masterbatch technology and powdered-rubber processing. A nonlatex method has been developed for the preparation of free-flowing solution-SBR powders. The factors affecting powder particle size and morphology have been identified. Optimization of the preparative variables has resulted in dry-blendable solution-SBR powders. As a consequence of a low shear history, the solution-SBR powder blends show distinctive rubber-filler, rheological, and physical properties. For example, unvulcanized solution-SBR powder compounds evince higher molecular weights and lower bound-rubber contents than conventional mixes. Yet, the microscopic filler dispersion of these two types of compounds appears similar. Uncured solution-SBR powder blends also exhibit stiffer rheological behavior than conventional mixes. Furthermore, this stiffness tends to persist in the vuleanizates derived from these powdered compounds. Vulcanizate excellence depends primarily upon fineness of the powder particles and absence of free filler. Conditions have been found which permit the direct ribbon extrusion of tire tread, without prior compacting or milling. Conventional single-screw ribbon- tread extruders are sufficient to produce treads of high quality.

Morphology of as-precipitated and dried powders in the PLZT system

1986 ◽  
Vol 44 ◽  
pp. 838-839
Author(s):  
R. W. Schwartz ◽  
D. A. Payne
Keyword(s):  
Freeze Drying ◽  
Ammonium Hydroxide ◽  
Ph Control ◽  
Continuous Reactor ◽  
Powder Particle Size ◽  
Oxide Ceramic ◽  
Chemical Preparation ◽  
Electro Optic ◽  
Particle Size And Morphology ◽  
Size And Morphology

High quality ceramic products, such as transparent electro-optic materials, require better control of chemical composition, powder particle size and morphology, than is offered by conventional mixed-oxide ceramic processing methods. Chemical preparation procedures can be used to prepare powders with the required characteristics of controlled size and morphology.Precipitated hydroxides in the PLZT system (lead lanthanum zirconium titanate) were prepared in a constant volume continuous reactor, following a procedure suggested by Murata, which uses nitrate and chloride precursors, and ammonium hydroxide for pH control. After washing with deionized water, the powders were dried by either spray-drying or freeze-drying in liquid nitrogen.

scholarly journals Preliminary investigations on extrusion of high viscosity slurry using direct writing technique

2020 ◽  
Vol 11 ◽  
pp. 15 ◽  
Author(s):  
Ali Tesfaye Kebede ◽  
Esakki Balasubramanian ◽  
AS Praveen ◽  
Lade Rohit ◽  
Kumar Arvind
Keyword(s):  
Flow Characteristics ◽  
High Viscosity ◽  
Curing Temperature ◽  
Solid Loading ◽  
Disruptive Technology ◽  
Internal Diameter ◽  
Solid Propellants ◽  
Direct Writing ◽  
The Cost ◽  
3D Printing Technique

Traditionally solid propellants are manufactured using casting and molding techniques. The effective burning rate of solid propellants is strongly depended on its cross section and geometry. The preparation of mold and mandrel for the manufacturability of various geometric profiles are tedious, time consuming, increases the cost and more human efforts are needed. In order to mitigate these issues, a disruptive technology called additive manufacturing (AM) is in the verge of development. Although the method is effective, additional study must be conducted to improve the flow characteristics of slurries for the high solid loading and there is a huge necessity to reduce the prolonged curing time. The present study focuses on preliminary investigations of extrusion of high viscosity slurry using a pneumatically driven extrusion system. The slurry was prepared with a 80 wt.% solid loading of NaCl having particle sizes of 45 µm and 150 µm, 15.6 wt.% HTPB, 2.2 wt.% TDI, 2.2 wt.% DOA and 0.03 wt.% of ferric acrylacetonate. The slurry was extruded with an aid of pneumatically controlled extruder and each layer was formed. Formed by extruding the slurry using 1.65 mm internal diameter nozzle. Infrared (IR) heater was utilized to transfer the radiational energy for partial curing of each layer and thereby adhesion of other layer was guaranteed. Simulation is performed to determine the temperature distribution using ANSYS platform for comparing the curing temperature of the printed part top surface. Preliminary experiments confirm that extrusion of slurry and heating of each layer can be effectively achieved with the proposed 3D printing technique. Three tensile specimens were produced in accordance with ASTMD 412-C and their corresponding mechanical properties are evaluated. The printed parts have the tensile strength of 0.7 MPa, elongation of 4.85 % and modulus of elasticity of 18.5 MPa which are comparable with the properties of conventional casted part.

ULTRAFINE PRIMARY SILICON PARTICLES IN PHOSPHORUS-MODIFIED HYPEREUTECTIC AL-SI ALLOY POWDERS PRODUCED BY SAMD METHOD

2008 ◽  
Vol 22 (18n19) ◽  
pp. 3304-3310 ◽  
Author(s):  
P. DELSHAD-KHATIBI ◽  
F. AKHLAGHI
Keyword(s):  
Primary Silicon ◽  
Powder Particle Size ◽  
Primary Si ◽  
Solid Media ◽  
Aluminum Droplets ◽  
Rotating Impeller ◽  
Powder Particles ◽  
Size And Morphology ◽  
Phosphorus Modification ◽  
Average Size

In the present study, alloy powder batches of Al-20Si (wt. %) were generated by SAMD technique using NaCl as the solid media. The method consists of introducing and mixing a specified amount of NaCl particles (mean diameter 254 μm) in aluminum melt at the temperature of 710°C. Melt disintegration occurs in 5 min by kinetic energy transfer from a rotating impeller (1400 rpm) to the metal via the solid atomizing medium ( NaCl particles). The resulting mixture of aluminum droplets and NaCl particles are subsequently quenched in water to dissolve NaCl and solidify Al droplets to produce powder particles. In order to investigate the effect of phosphorus modification on the size and morphology of the primary Si particles, the SAMD technique was also performed to produce Al-20Si -0.015P powder particles. The resultant powders were screened through 6 different sized sieves ranging from 38 to 500 μm and different powder fractions were cold mounted, polished and studied by optical microscopy. It was concluded that for both un-modified and modified alloys, there was a decrease in the size of primary Si particles corresponding to a decrease in the powder particle size. However, the same sized phosphorus modified powders exhibited considerably finer primary Si particles in which the average size of these ultrafine Si particles was about 1.1 μm for the smallest sieved particles.

Direct manipulation of particle size and morphology of ordered mesoporous silica by flow synthesis

RSC Advances ◽  
2015 ◽  
Vol 5 (18) ◽  
pp. 13331-13340 ◽  
Author(s):  
T. N. Ng ◽  
X. Q. Chen ◽  
K. L. Yeung
Keyword(s):  
Particle Size ◽  
Mesoporous Silica ◽  
Hollow Spheres ◽  
Ordered Mesoporous Silica ◽  
Direct Manipulation ◽  
Flow Synthesis ◽  
Precise Control ◽  
Ordered Mesoporous ◽  
Particle Size And Morphology ◽  
Size And Morphology

Flow-synthesis of mesoporous silica allows deliberate and precise control over the size and shapes and enables the preparation of complex microstructures (i.e., hollow spheres).

Preparation of High-Purity Ultrafine α-Al2O3 by Solid-State Reaction at Room Temperature

2008 ◽  
Vol 368-372 ◽  
pp. 683-685
Author(s):  
Cheng Wei Hao ◽  
Bo Lin Wu ◽  
Ji Yan Li
Keyword(s):  
Solid State ◽  
High Purity ◽  
Solid State Reaction ◽  
Room Temperature ◽  
Raw Materials ◽  
Phase Particle ◽  
Phase Transformation Temperature ◽  
Particle Size And Morphology ◽  
Size And Morphology ◽  
Α Al2o3

Ammonium aluminium carbonate hydroxide (AACH), with a small quantity of γ-AlOOH, was synthesized through solid-state reaction at room temperature using AlCl3·6H2O and NH4HCO3 as raw materials and polyethylene glycol (PEG-10000) as the dispersant. After calcined at 1100°C for 1.5h, α-Al2O3 powders with primary particle sizes of 20~30nm were obtained. The crystal phase, particle size and morphology of the high-purity ultrafine α-Al2O3 were characterized. The results showed that a small quantity of γ-AlOOH in the AACH decomposed and formed crystal seeds. The presence of crystal seeds reduced the nucleation activation energy and therefore reduced the phase transformation temperature.

scholarly journals Synthesis and Characterization of a Fe3O4@PNIPAM-Chitosan Nanocomposite and Its Potential Application in Vincristine Delivery

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1704
Author(s):  
Cynthia N. Hernández-Téllez ◽  
Ana G. Luque-Alcaraz ◽  
Maribel Plascencia-Jatomea ◽  
Hiram J. Higuera-Valenzuela ◽  
Mabeth Burgos-Hernández ◽  
...  
Keyword(s):  
Fe3o4 Nanoparticles ◽  
Release Kinetics ◽  
Magnetic Core ◽  
Systematic Evaluation ◽  
Solution Temperature ◽  
Core Shell ◽  
Particle Size And Morphology ◽  
Size And Morphology ◽  
Thermomagnetic Properties ◽  
Release Model

In this research, we conducted a systematic evaluation of the synthesis parameters of a multi-responsive core-shell nanocomposite (Fe3O4 nanoparticles coated by poly(N-isopropylacrylamide) (PNIPAM) in the presence of chitosan (CS) (Fe3O4@PNIPAM-CS). Scanning electron microscopy (SEM) was used to follow the size and morphology of the nanocomposite. The functionalization and the coating of Fe3O4 nanoparticles (Nps) were evaluated by the ζ-potential evolution and Fourier Transform infrared spectroscopy (FTIR). The nanocomposite exhibited a collapsed structure when the temperature was driven above the lower critical solution temperature (LCST), determined by dynamic light scattering (DLS). The LCST was successfully shifted from 33 to 39 °C, which opens the possibility of using it in physiological systems. A magnetometry test was performed to confirm the superparamagnetic behavior at room temperature. The obtained systems allow the possibility to control specific properties, such as particle size and morphology. Finally, we performed vincristine sulfate loading and release tests. Mathematical analysis reveals a two-stage structural-relaxation release model beyond the LCST. In contrast, a temperature of 25 °C promotes the diffusional release model. As a result, a more in-depth comprehension of the release kinetics was achieved. The synthesis and study of a magnetic core-shell nanoplatform offer a smart material as an alternative targeted release therapy due to its thermomagnetic properties.

scholarly journals Dehumidified Air-Assisted Spray-Drying of Cloudy Beetroot Juice at Low Temperature

2021 ◽  
Vol 11 (14) ◽  
pp. 6578
Author(s):  
Aleksandra Jedlińska ◽  
Alicja Barańska ◽  
Dorota Witrowa-Rajchert ◽  
Ewa Ostrowska-Ligęza ◽  
Katarzyna Samborska
Keyword(s):  
Particle Size ◽  
Physicochemical Properties ◽  
Spray Drying ◽  
Low Temperatures ◽  
Beetroot Juice ◽  
Particle Size And Morphology ◽  
Size And Morphology ◽  
Tapped Density ◽  
Lower Loss ◽  
Better Than

This paper discusses the physicochemical properties of powders obtained by spray drying of cloudy beetroot juice, using dehumidified air in variants with or without carriers. The inlet air temperature was 130 °C or 90 °C, and the addition of the carriers was at a ratio of juice to carrier solids of 3:2. In the obtained powders, the following physicochemical properties were determined: water content and water activity, apparent density, loose and tapped density, porosity, flowability, particle size and morphology, and the content and retention of betalains. It was possible to dry cloudy beetroot juice without the use of carriers at low temperatures (90 or 130 °C). The 100% beetroot powders were characterized by satisfactory physicochemical properties, often better than those with carriers (including lower hygroscopicity and higher color saturation and yield). A lower loss of betalains was found for the powders with the addition of carriers. The best process yields were obtained for the powder without carriers at 130 °C and 90 °C.

Prediction of High Viscosity Liquid/Gas Two-Phase Slug Length in Horizontal and Slightly Inclined Pipelines

2021 ◽  
Author(s):  
Omar Shaaban ◽  
Eissa Al-Safran
Keyword(s):  
Numerical Optimization ◽  
Flow Behavior ◽  
Mechanistic Model ◽  
High Viscosity ◽  
Oil Well ◽  
Liquid Slug ◽  
Two Phase ◽  
Proposed Model ◽  
Wide Range ◽  
Flow Closure

Abstract The production and transportation of high viscosity liquid/gas two-phase along petroleum production system is a challenging operation due to the lack of understanding the flow behavior and characteristics. In particular, accurate prediction of two-phase slug length in pipes is crucial to efficiently operate and safely design oil well and separation facilities. The objective of this study is to develop a mechanistic model to predict high viscosity liquid slug length in pipelines and to optimize the proper set of closure relationships required to ensure high accuracy prediction. A large high viscosity liquid slug length database is collected and presented in this study, against which the proposed model is validated and compared with other models. A mechanistic slug length model is derived based on the first principles of mass and momentum balances over a two-phase slug unit, which requires a set of closure relationships of other slug characteristics. To select the proper set of closure relationships, a numerical optimization is carried out using a large slug length dataset to minimize the prediction error. Thousands of combinations of various slug flow closure relationships were evaluated to identify the most appropriate relationships for the proposed slug length model under high viscosity slug length condition. Results show that the proposed slug length mechanistic model is applicable for a wide range of liquid viscosities and is sensitive to the selected closure relationships. Results revealed that the optimum closure relationships combination is Archibong-Eso et al. (2018) for slug frequency, Malnes (1983) for slug liquid holdup, Jeyachandra et al. (2012) for drift velocity, and Nicklin et al. (1962) for the distribution coefficient. Using the above set of closure relationships, model validation yields 37.8% absolute average percent error, outperforming all existing slug length models.

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