Powder Injection Process Research Articles

Numerical Analysis of Fluid Flow and Powder Transport Characteristics of RH-Degasser Ladle Bottom Powder Injection (RH-PBI) Process

Numerical Analysis of Fluid Flow and Powder Transport Characteristics of RH-Degasser Ladle Bottom Powder Injection (RH-PBI) Process

Hot metal dephosphorization process using calcium ferrite slag without fluorite

ABSTRACT To solve environmental pollution caused by using fluorite slagging in the process of hot metal dephosphorization, this paper applies pre-melted calcium ferrite slag in the production of stainless steel powder injection and oxygen dephosphorization process to replace fluorite slagging. The results show that the average hot metal dephosphorization rate of calcium ferrite slagging is 88.06%, and its dephosphorization effect is better than that of fluorite slagging. The average hot metal dephosphorization rate of fluorite slagging is 77.7%. The slag melting temperature during calcium ferrite slagging is 1137°C on average, which is lower than the melting temperature of fluorite slagging, and the slag melting temperature during fluorite slagging is 1296°C on average. When calcium ferrite slagging, the slag melting condition is good during the blow process. According to the results of material cost estimation, it is completely feasible to substitute calcium ferrite slag for fluorite slagging.

Powder injection molding of PNN-PMN-PZN doped low temperature sintering PZT ceramics

A complete process of powder injection molding was developed and optimized for the low temperature sintering PZT ceramics. A commercialized PNN-PMN-PZN doped PZT ceramics was used for the process development. The torque rheometer experiment was conducted to determine the optimal solids loading to injection molding rectangular type specimen. Appropriate debinding conditions were developed by thermogravimetry. Holding temperatures were determined based on the decomposition behavior of binder system and the volatilization temperature of Pb. Due to the fine particle size and low solids loading, a slow thermal debinding rate was required to prevent the crack defect. The densification behavior during sintering was analyzed by dilatometry. Low temperature sintering PZT ceramics shows a strain rate peak point at 1015°C which is relatively lower than the peak point of conventional PZT ceramics. Even though a relatively long (3h) holding time was required to achieve 98% of relative density, the powder injection molded low temperature sintering PZT ceramics showed 7.66 (103kg/m3) of density and 635 (pC/N) of piezoelectric charge constant which are 98 and 99% of reference value of powder.

Experiments of eliminating the destructive effects of excessive Fe inclusions for Al secondary products

Excessive Fe content in Al alloys caused the serious decline of mechanical properties, such as the ductility and impact toughness. Carried out the experiments of eliminating the destructive effects of excessive Fe content by flux-adding technology, which including removing a part of Fe content from Al scrap melt and modifying the morphology of Fe rich precipitates. The experimental results showed that, the ratio of removing Fe element was above 20%, and the morphology of Fe rich precipitates changed from Lamellar to bulk or lath precipitations under the process parameters: the fluxing-agents composed of borax, and MnCl2 (mixed by mass ratio of 1:1), and the adding amount of fluxing-agents was about 1.5%; thrown the fluxing-agents into the Al scrap melt by powder injection process and kept for 30 min.

Bio-inspired piezoelectric artificial hair cell sensor fabricated by powder injection molding

A piezoelectric artificial hair cell sensor was fabricated by the powder injection molding process in order to make an acoustic vector hydrophone. The entire process of powder injection molding was developed and optimized for PMN–PZT ceramic powder. The artificial hair cell sensor, which consists of high aspect ratio hair cell and three rectangular mechanoreceptors, was precisely fabricated through the developed powder injection molding process. The density and the dielectric property of the fabricated sensor shows 98% of the theoretical density and 85% of reference dielectric property of PMN–PZT ceramic powder. With regard to homogeneity, three rectangular mechanoreceptors have the same dimensions, with 3 μm of tolerance with 8% of deviation of dielectric property. Packaged vector hydrophones measure the underwater acoustic signals from 500 to 800 Hz with −212 dB of sensitivity. Directivity of vector hydrophone was acquired at 600 Hz as analyzing phase differences of electric signals.

Researches Regarding the Influence of Technological Parameters on the Alloying Efficiency in Powder Injection Process

The injection of the powdered materials into molten melts is a common practice in the metallurgical technology of steel refining and alloying. During process development, within the metal bath is formed a mixed three-phase with different structures depending on the parameters of the hydrodynamic injection. The “plume zone” represents a domain inside of the molten metal in which takes place the forming, coalescence and disintegration of the gas bubbles, that penetrate into the molten metal together with the powdered material. The “plume zone” is the primary contact zone between the powdered particles and the molten metal. Inside of contact zone is take place the chemical reactions between the reactive material and the metal bath components. The “plume zone” size, shape and structure are functions of the hydrodynamic parameters of the injection process, the most important being the injection speed. The size of this parameter leads at the appearance of a multitude of possible structures types of the metal bath. These structures dictate the metallurgical process efficiency in defining the steelmaking process and refining of metal bath. In the present paper are investigated and discussed the “plume zone” structures formed during injection with graphite particle of a molten steel bath and the metallurgical results obtained experimentally under the influence of the injection velocity.

Influence of Specimen Dimensions and Temperature on the Debinding Behavior of Alumina Feedstock

This work investigated the influence of specimen dimensions and temperature on the debinding behavior of alumina feedstock for powder injection process. Polyethylene glycol (PEG) was used as a based binder. It is soluble in water therefore the use of wax-based binder system can be avoided. PEGs with a molecular weight of 1500 and 4000 were mixed with polyvinyl butyral (PVB) a minor component. Stearic acid was added during feedstock preparation to act as a lubricant. Debinding process was carried out using a water leaching test at 30 and 70 °C to study for PEG removal rate. Specimens retained their shapes after leaching of the binders. In general, the rate of binder removal increased at initial stage then slowed down at longer leaching times. A faster debinding rate was achieved at 70 °C when compared to 30 °C. In addition, samples with a higher surface area to volume ratio (As/V) led to an increase in the %PEG removal rate. This study also showed the relationship between %PEG removal as a function of different surface area to volume ratio (As/V) which can be helpful in predicting %PEG removal for any other samples having cylindrical shape.

Process Validation of Ceftriaxone and Sulbactam Dry Powder Injection

In the present work Process validation of Ceftriaxone and Sulbactam as a dry powder injection was carried out. As the manufacturing process of dry powder injection is mainly dependent on blending process. In the present investigation, blending process was validated at different speeds of blender and the % assay was estimated by HPLC method. The octagonal blender was operated at 13, 17 and 20 rpm samples were taken from 10 different locations inside the blender. At 13 rpm there is much variation in assay results, at 17 rpm there is very less variation and also at 20 rpm there is slight variation occurs with reference to the acceptable ranges of assay {i.e. 90-110 %}. The obtained results clearly indicated that the optimum rpm is often necessary for the proper mixing of the drug. Therefore, 17 rpm was considered for the proper mixing at blending stage and it can be successfully employed to manufacture of dry powder injections for further manufacturing. The content uniformity of the net filled content was found to be in ± 5 % of average net content. Hence, it was concluded that process stands validated for the preparation of dry powder injection.

Two component tungsten powder injection molding – An effective mass production process

Tungsten and tungsten-alloys are presently considered to be the most promising materials for plasma facing components for future fusion power plants. The Karlsruhe Institute of Technology (KIT) divertor design concept for the future DEMO power plant is based on modular He-cooled finger units and the development of suitable mass production methods for such parts was needed.A time and cost effective near-net-shape forming process with the advantage of shape complexity, material utilization and high final density is Powder Injection Molding (PIM). This process allows also the joining of two different materials e.g. tungsten with a doped tungsten alloy, without brazing.The complete technological process of 2-Component powder injection molding for tungsten materials and its application on producing real DEMO divertor parts, characterization results of the finished parts e.g. microstructure, hardness, density and joining zone quality are discussed in this contribution.

Investigation on comprehensive performance of the EFI by MIM technology

Metal Injection Molding (MIM) technology is introduced into EFI production processing. Magnetic circuit of EFI is designed, and three different kinds of EFI samples are manufactured. Through comparisons of simulation and ex- periments, comprehensive performance of one EFI sample, which is made of Fe-based nanocrystalline soft magnetic alloy by MIM is found to be obviously better than that of others, which are made of traditional material and processing. The dynamic response times of opening and closing are respectively shorter by 32.5% and 62.2%, and dynamic flow range is wider by 8.3%. The electronic fuel injector (EFI) is a key actuator of gasoline engine, which decides precision of fuel injection, so characteristics of EFI, such as accuracy, consistency and stability, are mostly important for engine fuel injecting system. The key parts of injector are traditionally made of soft magnetic alloy bar through metal machining process, technology of which is characterized by low efficiency, material utilization and poor consistency. Moreover, cutting stress, caused while cut- ting, would lead to permeability of soft magnetic materials decreasing, coercivity and magnetic wastage increasing (1). Metal Injection Molding (MIM) known as the most popular parts forming technology, is a new near-net shaping technique (2). MIM technology is a product of multi- disciplinary cross-penetration, such as plastic injection molding polymer chemistry, powder metallurgy technology and metal material science (3). High density, high precision and high strength parts can be manufactured rapidly by MIM technology. MIM can be traced back to 1920's, when ceramic spark plug was prepared with process of powder injection molding. Several decades from then, powder injection molding was mainly applied to ceramic injection molding. Until 1979, Par- match Co., establishedby Wiech, turned its application from powderinjection molding into metal injection molding for first time (4). Through almost twenty years of development, MIM technol- ogy is widely used in aerospace, weapon, car, tools, teeth materials, medical materials, national defense and people's livelihood industry (5-12), for its advantages of high productivity, high precision and high performance.

Experimental evaluation of the new lance for powder injection

The paper presents the results of the evaluation experiments of the new lance for powder injection process. The pneumatic powder injection process itself has been well known since many years and it can be operated both with submerged and non-submerged lance. The new invented by authors injection lance is dedicated for processes without its submersion especially when the powders are injected into liquid metal bath inside the ladles or induction crucible furnaces. In these cases it is important to not introduce the carrier gas into metal volume to make the temperature decrease as low as possible. However, when the lance is not submerged the problem with particles jet introduction into liquid metal with proper distribution appears. The new lance of special design with slots and flange at the outlet was checked both in model water experiments and real conditions for ferroalloys injection into liquid cast grey iron. The results proved the efficiency of the powder introduction and low liquid alloy temperature decrease, too.

Two-Phase Jet in Process of Pneumatic Powder Injection into Liquid Alloy

The short description of the new approach to the pneumatic powder injection process analysis was presented in the article. The experiments with the high speed camera recording of the two-phase jet in pneumatic powder injection process were carried out in the Department of Foundry, Silesian University of Technology, Poland. The results were briefly analyzed and some interesting conclusions appeared, especially that the real velocity of the injected particles is far less than it is normally calculated with use of the well-known formulas. They were compared with existing literature data as well as with some experimentspreviously made by authors. Powder particles velocity and two-phase jet mass concentration were analyzed as the most important parameters for powder injection process. The results described are part of the complex experimental plan and the next step is computer modeling (just launched) of the jet introducing liquid.

Influence of particle properties on the size of agglomerated metallurgical powders

The disintegration of agglomerates of solid charge used in a nickel flash furnace has been investigated to improve the understanding and modelling of furnace operation. A laboratory-scale experimental rig was constructed to non-intrusively measure the agglomerate size distribution of solid charge suspended in air, and to observe the powder injection process. Measurements indicated sizes from 200 to 7000 μm of agglomerated solid charge were present under turbulent conditions similar to that experienced in a flash furnace. The current work indicates that the primary particle size distribution of feed significantly affected the size of suspended agglomerates that were formed, while the amount of fine (−38 μm) material strongly influenced the strength of agglomerates. Specifically, increasing the concentration of −38 μm particles in nickel concentrate from 42 vol.% to 66 vol.% increased the volume of agglomerated material by a factor of more than 7. The effect of particle packing was shown to influence the agglomerate size distribution of feed, although this effect was inconsistent and required more study. Experiments investigating the effect of particle shape on agglomerate size showed only a slight effect that may not be significant. It is expected that reducing the amount of fine material in flash furnace feed would cause a decrease in agglomerate sizes within the reaction shaft, and lead to faster reaction times. It is recommended that the agglomerability of furnace feed be taken into account in computational models of flash furnace reactions in future work.

Process simulation of powder injection moulding: identification of significant parameters during mould filling phase

Simulating and optimising the powder injection process are complex problems since a number of linked material, geometry and process variables have to be considered. In addition, it is very difficult to identify critical parameters for designing binder systems, feedstocks, parts, moulds and processing conditions owing to the fact that multiple objective functions have to be considered. Towards the goal of identifying the level of significance of various material, process and geometry parameters during powder injection moulding, a systematic procedure for sensitivity analysis has been successfully developed for the mould filling phase of the PIM process. In this sensitivity analysis, all input parameters were defined for the mould filling simulation and all output parameters for optimum design of part, mould and processing conditions and dimensionless sensitivity values for all input and output parameters were calculated, which allow parameters with different units to be compared quantitatively. The sensitivity analysis procedure developed will be an invaluable tool for both the design engineer in the PIM industry who has to determine the critical input parameters for given design targets, as well as for the production engineer who has to optimise and monitor the production stage.

Physical Simulation of Powder Injection Process in a Torpedo‐car

Through systematical physical simulation of powder injection process in a torpedo‐car, the influences of operation parameters on process variables such as uniform mixing time, powder penetration ratio and residence time are determined. The relationships between the operation parameters and the process variable are obtained using linear regression method. Finally, the optimum operation parameters for powder injection are found using multi‐objective nonlinear programming method.

Mathematical model for condensed-solvent debinding process of PIM

Based on Fick’s diffusion law, mathematical model for specimens with simple shapes such as slab, sphere and cylinder are developed for condensed-solvent debinding process of powder injection molding. A graphical method is introduced to forecast the debinding process using the established model while complicated calculation could be avoided. Experiments are carried out to verify the mathematical model and graphical method, and the results are very close to those calculated from the up-mentioned model and method.

Three-dimensional finite element modeling of laser cladding by powder injection: Effects of powder feedrate and travel speed on the process

This article addresses a novel three-dimensional transient finite element model of the laser cladding by powder injection process. The proposed model can predict clad geometry as a function of time and process parameters including beam velocity, laser power, powder jet geometry, laser pulse shaping, and material properties. In the proposed method, the interaction between powder and melt pool are assumed to be decoupled and as a result, the melt pool boundary is first obtained in the absence of powder spray. Once the melt pool boundary is calculated, it is assumed that a layer of coating material based on powder feedrate and elapsed time is deposited on the intersection of the melt pool and powder stream in the absence of laser beam. The new melt pool boundary is then calculated by thermal analysis of the deposited powder layer, substrate and laser heat flux. The results of numerical modeling for different process velocities and different powder feedrates are presented and compared with experimental results. The comparisons show a good agreement between the modeling and experimental geometry of the clads.

Inyección de mineral de manganeso en acero líquido

A theoretical and experimental analysis is carried out to estimate the rate of MnO reduction when manganese ore is injected into liquid steel with three carbon contents, 0.5, 1.0 and 2.0 mass % at 1600 °C. It is assumed that there are two reaction zones along the flux injection operation: a transitory reaction between the rising particles and the bulk metal, and the permanent reaction between the metal and the top slag. The experiments were carried out in an open 10 kg induction furnace using A1203 refractory. The results show that the transitory reaction plays a more important role in the powder injection process than the permanent reaction. The reduction of MnO with silicon is more important when the basicity of the slag is high; this is because the aSi02 decreases as the slag basicity is increased. However, when the slag basicity is low and the initial carbon content in steel is high the reduction of MnO with silicon becomes less efficient, although silicon still remains better reducing agent than carbon.

Metallic powder injection molding using low pressure

The demand by high performance materials that have to support severe service conditions at a reasonable cost has been forcing the powder metallurgy to improve constantly. The most recent and more important innovation in the area is the process of powder injection. Powder injection molding (PIM) is a technology capable of producing a new range of components from powders. This advanced technology overcomes the existent limitations in the forming of products with complex geometry. The process presents countless variations which are used in the industry today. Invariably, it consists of mixing the powders and a thermo-plastic binder, injecting the mass in the mold in the wanted form, debinding, sintering and making optional secondary operations, as for example, machinery. The purpose of this work is to review the metal injection molding techniques and apply the low pressure injection molding process to family of parts using metallic powder with 10 μm particle size. This work also comments the design and construction of a low pressure injection machine and injection molds.

Carbon Control in PIM Tool Steel

The unique physical and mechanical properties of the M-group tool steels and the ease to sinter the powder compacts of these materials into near full density make them good candidates for powder injection molding. The major disadvantage of these tool steels is their moderate sensitivity to sintering and hardening conditions and their tendency to decarburization. The key to success in PIM of these materials is carbon control during presintering and sintering. Since the sintering mechanism of this type of material is “supersolidus”, the sintering temperature and the carbon content are the most important process variables because these dictate the volume fraction of liquid. This paper describes the process of powder injection molding (PIM) of M-2 tool steel, and its debinding, presintering, and sintering processes with the resultant properties. The effect of processing variables on the resulting properties is also evaluated. The focus is on carbon control and its effect on the final properties.