Authors: Jong Gwan Ahn, Dong Jin Kim, Jae Ryeong Lee, H.S. Jung, Byoung Gyu Kim
Abstract: The synthesis of spherical silver powders by chemical reduction method was investigated.
Conductive metal pastes to have good properties in adhesion, stability, and conductivity, it is very
important to control the purity, size, and shape of metal particles. In the present study, proper
methods to control the properties of micron sized metal powders for conductive pastes are
investigated. Chemical reduction method in aqueous solution was adapted to produce silver powder.
The effects of reaction time, concentration of reductant and additives, and stirring speed were
investigated, in experimental. Fine spherical silver powder of 0.5 to 3 ㎛ were synthesized from silver
nitrate solution with hydroquinone as a reducing additive by liquid phase method, and some variables
and reaction mechanism in conjunction with the particle morphology and size were studied.
Authors: Lin Wang, Jia Xiang Zhong, Bin Ma, Shu Jun Wang
Abstract: In this paper, the application of new functional nano-material films prayed on transmission
display screen is studied. Optical properties, such as luminance gain and scattering angle, of the screens
are measured to investigate the particle size effects on the properties. The results show that the optical
properties of screen sprayed with nano-material film improve notably compared with those screens with
films of conventional particle sizes. When the particle size is less than 100nm, the gain is high and the
viewing angle low. With increasing particle sizes, the characteristics of screens vary with particle sizes. In
order to solve the contradictory relationship between gain and viewing angle and to obtain screens with
desirable optical properties, suitable nano-particle sizes ranging from 400nm to 700nm should be chosen
for the spraying film. The scattering mechanisms between nano-particles and light are also discussed.
Authors: Ioan Vida-Simiti, Nicolaie Jumate, Valentin Moldovan, Niculina Sechel, György Thalmaier
Abstract: Spherical bronze powders were used for studies the obtaining of gradual porous structures by sedimentation and sintering methods. The powder size classes above 100 μm were used for the manufacturing of the macroporous support by spreading the powder into the sintering die. Sintering was conducted in vacuum (10-4 Torr) at a temperature of 750 °C for 40 minutes. On the macroporous support a layer of fine powder fraction was deposited by gravitational sedimentation. The deposited layers were consolidated by sintering at 750 °C for 30 minutes. The analysis of the gradual porous layers was done using scanning electron microscopy and mercury porosimetry. The fluids viscosity influences the sedimentation velocity of particles. The height of the column directly affects the quality of porous structure. If the sedimentary column is short, the turbulences created by adding the suspension of the dispersed powder in the sedimentary tube are more harmful.
Authors: Zheng Min Li, Zhi Wei Chen, Min Tan, Ke Jing Xu, Bing Jiang
Abstract: Nano-TiO2 coating film is one of the efficient photocatalysts. The particle size distribution of TiO2 has important influence on photocatalytic activity. A new method to determine the particle size distribution of TiO2 nano-film coated on ceramic was developed, by which the images of film acquired by Atom force microscope (AFM) were processed, and TiO2 particles contacted with others were separated and detected. The particle size distributions of two TiO2 nano-films were determined.
Authors: Bing Jiang, Zheng Min Li, Han Zhai, Zhi Wei Chen, Hong Guo, Jin Ye Niu, Min Tan
Abstract: Determination of particle size and shape factors of the corundum powders by SEM image analysis has been reported in our preceding work. However, the effect of sample preparation and image processing has not been investigated. In order to obtain appropriate images, samples was well-dispersed by vibrating particles manually up and down, and then thicker Pt coating was well sputter coated on the surface of samples; compared with the magnifications of 100 and 32, magnification of 50 was more reasonable; for distinguishing particles from image background properly, the gray threshold value of 70 was set to transform gray image to binary image; to decrease image noises, three image filters, i.e. Erosion Filter, Dilation Filter and Median Filter were investigated and the last one was the most effective. This method of sample preparation and image processing can be used in regular and irregular particles determination.