• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09a
• /
• pp.518-519
• /
• 2006

A connection between pulse-periodical laser radiation power and stability of liquid-metal contacts between powder particles during selective laser sintering (SLS) is determined based on analysis solving the problem of stability of liquid column in the gravity and capillary forces field. On the grounds of obtained relationships the optimization of pulse-periodical laser radiation power and SLS-process duration is realized, that allows to produce voluminous powder porous materials with pre-determined physical and mechanical properties and surface geometry. Results of metallographic investigations of powder porous materials of titanium powder produced with technological regimes calculated by means of obtained relationships are given in the work

• The Journal of Korean Medicine
• /
• v.17 no.2 s.32
• /
• pp.245-250
• /
• 1996

This study was conducted to investigation into production of bile juice and bile powder by Chinese moon bear. The color of bile juice and bile powder were appeared to bronze and bronze or yellowlish brown. Average production of bile juice(ml) and bile powder(g) per head and the powdered rate(%) of bile juice were 98.4ml, 20.8g and 20.4% during a surgical operation. Production of bile juice(ml) and bile powder(g) per head were appeared to 120.7ml-139.5m1 and 8.5g-10.2g during experimental period(31 days), respectively. Average daily production of bile powder(g) per head and the collectting days of bile juice was decreased; to 6.7g and 52.5 day in summer compared with another season(10.3g and 60 days) The production of bile juice and bile powder was not difference between seven times collection in 7 days and once collection in 7 days.

• Korean Journal of Food Science and Technology
• /
• v.22 no.2
• /
• pp.183-191
• /
• 1990

Soy milk prepared from soy protein concentrate was added with each of four types of milk products. Acid production and growth of five species of lactic acid bacteria(LAB) in soy milk and sensory property of soy yogurt were investigated. Acid production by LAB increased in proportion to concentration of milk products added to soy milk. Among the four milk products tested, whey powder or skim milk powder stimulated acid production by LAB more than whole milk powder or modified milk powder. Stimulating effect by whey powder on acid production by LAB was greater than other milk products at low concentration. Acid production by LAB in soy milk added with glucose or milk products significantly increased during fermentation. Sensory property of soy yogurt added with whole milk powder or skim milk powder was better than that of reference (soy yogurt added with glucose) while sensory property of soy yogurt added with whey powder or modified milk powder was Inferior to that of reference.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09a
• /
• pp.14-15
• /
• 2006

In this study, a new laval type nozzle was designed and manufactured. Using this nozzle tin powder was produced in close coupled system by using nitrogen gas at different operating conditions. The results showed that the increasing the gas pressure up to 1.47 MPa reduced the mean powder size down to 11.39 microns with a gas/melt mass flow rate ratio of 2.0. Powders are spherical in shape and have smooth surfaces.

• Journal of ILASS-Korea
• /
• v.11 no.2
• /
• pp.59-68
• /
• 2006

Experimental results of the metal powder production with internal mixing, internal impinging and the atomizer coupled with substrate design are presented in this paper. In a test with internal mixing atomizer, mean powder size was decreased from $37{\mu}m\;to\;23{\mu}m$ for Pb65Sn35 alloy as the gas-to-melt mass ratio was increased from 0.04 to 0.17. The particle size further reduces to $16.01{\mu}m$ as the orifice area is increased to $24mm^2$. The micrograph of the metal powder indicates that very fine and spherical metal powder has been produced by this process. In a test program using the internal impinging atomizers, the mean particle size of the metal powder was decreased from $22{\mu}m\;to\;12{\mu}m$ as the gas-to-melt-mass ratio increased from 0.05 to 0.22. The test results of an atomizer coupled with a substrate indicates that the deposition rate of the molten spray on the substrate is controlled by the diameter of the substrate, the height of the substrate ring and the distance of the substrate from the outlet of the atomizer. This in rum determines the powder production rate of the spraying processes. Experimental results indicate that the deposition rate of the spray forming material decreases as the distance between the substrate and the atomizer increases. For example, the deposition rate decreases from 48% to 19% as the substrate is placed at a distance from 20cm to 40cm. On the other hand, the metal powder production rate and its particle size increases as the subsrate is placed far away from the atomizer. The production of metal powder with mean particle size as low as $3.13{\mu}m$ has been achieved, a level which is not achievable by the conventional gas atomization processes.

• Journal of Powder Materials
• /
• v.9 no.4
• /
• pp.267-272
• /
• 2002

The production of micro components is one of the leading technologies in the fields of information and communiation, medical and biotechnology, and micro sensor and micro actuator system. Microfabrication (micromachining) techniques such as X-ray lithography, electroforming, micromolding and excimer laser ablation are used for the production of micro components out of silicon, polymer and a limited number of pure metals or binary alloys. However, since the first development of microfabrication technologies there have been demands for the cost-effective replication in large scale series as well as the extended range of available material. One such promising process is micro powder injection molding (PIM), which inherits the advantages of the conventional PIM technology, such as low production cost, shape complexity, applicability to many materials, applicability to many materials, and good tolerance. This paper reports on a fundamental investigation of the application of W-Cu powder to micro metal injection molding (MIM), especially in view of achieving a good filling and a safe removal of a micro mold conducted in the experiment. It is absolutely legitimate and meaningful, at the present state of the technique, to continue developing the micro MIM towards production processes for micro components.

• Steel and Composite Structures
• /
• v.15 no.2
• /
• pp.151-162
• /
• 2013

In this study, an electrolyzing device for the production of metal powders was designed and fabricated. The production of copper powders was performed using a variety of current densities, anode-cathode distances and power removal times. The effect of these parameters on powder particle size and shape was determined. Particle size was measured using a laser diffraction unit while the powder shape was determined by SEM. Experimental results show that an increase in current density leads to a decrease in powder particle size. In addition particle shape changed from globular dendritic to acicular dendritic with increasing the current density. Distance between the cathode and anode also showed a similar influence on powder particle size and shape. An increase in time of powder removal led to an increase in powder particle size, as the shape changed from acicular dendritic to globular dendritic.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09b
• /
• pp.1012-1013
• /
• 2006

A technology of hardening porous materials of titan powders has been elaborated. The technology is based on passing alternating current with duration of ${\sim}10^{-1}{\ldots}10^1$ s through porous ($35{\ldots}40%$) blanks made by method of Sintering by Electric Discharge (SED) by passing a pulse of current with duration of ${\sim}10^{-5}{\ldots}10^{-3}$ s. The influence of technological regimes of porous blanks treatment on their structure and properties is investigated. Geometry and dimension of contact necks between powder particles of obtained samples are evaluated. Variations of porosity and strengths as well as microstructure of porous samples materials before and after treatment are investigated. Optimum range of treatment technological regimes is determined within which porosity of $30{\ldots}35%$ with maximum strength values.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09b
• /
• pp.1331-1332
• /
• 2006

The present investigation has attemped to optimize hydrogen reduction process for the mass production of Fe-8wt%Ni nanoalloy powder from ball milled $Fe_2O_3-NiO$ powder. In-situ hygrometry study was performed to monitor the reduction behavior in real time through measurement of water vapor outflowing rate. It was found that the reduction process can be optimized by taking into account the apparent influence of water vapor trap in the reactor on reduction kinetics which strongly depends on gas flow rate, reactor volume and reduction.

• Journal of the Korean Society for Precision Engineering
• /
• v.15 no.2
• /
• pp.28-34
• /
• 1998

Powder metallurgy processes are able to form Net-Shape products and have been widely used in the production of automobile parts to improve its productivity. However, because of pores in powder products, the toughness of powder products are generally poor. Therefore, forged products are used in parts which suffer severe fatigue loads. In this paper, the choice of powder materials and production processes such as mixing, compaction, sintering, heat treatment to produce automobile spline hub are studied. Three type of materials are selected and processed and its microstructure and properties are investigated by tensile test, compression ring test, and impact test. Materials and processing methods are selected from the results. Finally, experimental spline hubs are manufactured by selected processes from selected powders and proved by torsional durability test.