• Archives of Pharmacal Research
• /
• 제5권2호
• /
• pp.53-60
• /
• 1982

The mixing of salicylic acid and wheat starch powders was studied using a V-type mixer. After the optimum operating conditions of the mixer were examined, the mixing characteristics relating to dilution ratio, particle size of active ingradient and addition ratio of lubricants were investigated. The coefficient of variation was expressed by a power law relating to the dilution ratio and the particle size of active ingredient. Furthermore, the comparison of results with the theoretically estimated value of mixing index suggested that the mixing of cohesive pharmacceutical powders is a complex stochastic process and cannot be explained fully by a simple theory based on a complete random mixing.

• Nuclear Engineering and Technology
• /
• 제52권8호
• /
• pp.1714-1723
• /
• 2020

This study aims at characterizing the rheological properties of uranium oxide powders for nuclear fuel pellets manufacturing. The flowability of these powders must be compatible with a reproducible filling of press molds. The particle size distribution is known to have an impact on the rheological properties and fine particles (<100 ㎛) are suspected to have a detrimental effect. In this study, the impact of the particle size distribution on the rheological properties of UO₂ powders was quantified, focusing on the influence of fine particles. Two complementary approaches were used. The first approach involved characterizing the powder in a static state: density, compressibility and shear test measurements were used to understand the behavior of the powder when it is transitioned from a static to a dynamic state (i.e., incipient flow conditions). The second approach involved characterizing the behavior of the powder in a dynamic state. Two zones, corresponding to two characteristic behaviors, were demonstrated for both types of measurements. The obtained results showed the amount of fines should be kept below 10 % wt to ensure a robust mold filling operation (i.e., constant mass and production rate).

• 한국축산식품학회지
• /
• 제42권6호
• /
• pp.915-927
• /
• 2022

Recently, protein-fortified milk powders are being widely consumed in Korea to prevent sarcopenia, and the demand for high-protein food powders is continuously increasing in the Korean market. However, spray-dried milk proteins have poor flowability and wettability owing to their fine particle sizes and high inter-particle cohesive forces. Fluidized bed agglomeration is widely used to improve the instant properties of food powders. This study investigated the effect of fluidized bed agglomeration on whey protein isolate (WPI)-fortified skim milk powder (SMP) at different SMP/WPI ratios. The fluidized bed process increased the particle size distribution, and agglomerated particles with grape-like structures were observed in the SEM images. As the size increased, the Carr index (CI) and Hausner ratio (HR) values of the agglomerated WPI-fortified SMP particles exhibited excellent flowability (CI: <15) and low cohesiveness (HR: <1.2). In addition, agglomerated WPI-fortified SMP particles exhibited the faster wetting time than the instant criterion (<20 s). As a result, the rheological and physical properties of the WPI-fortified SMP particles were effectively improved by fluidized bed agglomeration. However, the fluidized bed agglomeration process led to a slight change in the color properties. The CIE L^* decreased, and the CIE b^* increased because of the Maillard reaction. The apparent viscosity (η_a,10) and consistency index (K) values of the rehydrated solutions (60 g/180 mL water) increased with the increasing WPI ratio. These results may be useful for formulating protein-fortified milk powder with better instant properties.

• 한국안전학회지
• /
• 제20권2호
• /
• pp.105-112
• /
• 2005

This is to find out that cement mortar mixed with waste tie particle can be applied for recycling it and enhanced to have shock absorption capacity. Therefore, architectural material specification and its related references for the disposal of it are based on for the study. Test has been performed with procedure, based on the Korea Standard insulation mortar and Compressive Strength Test has been done at K remicon factory approved by Korea Government in Korea, in order to decrease any possible error in mixing procedure. Test molds far insulation capacity and cohesive strength have been delivered to the expert agency for having more exact results. The result from the above test shows that waste tyre mixed with cement mortar has almost equal to the common concrete. This means that the recycling of the waste t)re will be demanded more and more in case of having continued development for this recycling area. And also waste t)to-using construction material can be more applied for construction area than existing material. Thus, this recycling method can be very usefully applied for solving environmental problem and for establishing economic aspect.

• 한국분말재료학회지
• /
• 제29권2호
• /
• pp.99-109
• /
• 2022

Powder flowability is critical in additive manufacturing processes, especially for laser powder bed fusion. Many powder features, such as powder size distribution, particle shape, surface roughness, and chemical composition, simultaneously affect the flow properties of a powder; however, the individual effect of each factor on powder flowability has not been comprehensively evaluated. In this study, the impact of particle shape (sphericity) on the rheological properties of Ti-6Al-4V powder is quantified using an FT4 powder rheometer. Dynamic image analysis is conducted on plasma-atomized (PA) and gas-atomized (GA) powders to evaluate their particle sphericity. PA and GA powders exhibit negligible differences in compressibility and permeability tests, but GA powder shows more cohesive behavior, especially in a dynamic state, because lower particle sphericity facilitates interaction between particles during the powder flow. These results provide guidelines for the manufacturing of advanced metal powders with excellent powder flowability for laser powder bed fusion.

• 산업기술연구
• /
• 제25권B호
• /
• pp.127-133
• /
• 2005

Manufacturing methods of Nano particles can be distinguished by top-down technology as physical method and bottom-up technology as chemical synthetic method. Top-down technology is a kind of method for making microstructure as like carving after forming a macroscopic structure in advance and its typical methods are ball milling, gas condensation method and so on. Nano Particles synthesized by bottom-up method have got to do dispersing process for using them as actual nano particles because their viscosity are very strong and so easy to shape cohesive substances. Therefore, this study is about a particle separating device which separates a certain constant size of grains processed already in mill and mixer because we mostly use media agitating mill as a device of milling and dispersing and we necessarily use very slight balls as media for manufacturing nano particles in the machine. The centrifugal device has been designed for passing and separating below a certain type of grain size after final process of particles in the mill.