Preparation and post-treatment of silver powders for front contact pastes of silicon solar cells

Corrugated-surface silver powders were prepared for front contact pastes of silicon solar cells. The effects of using different pH controlling agents on the powder diameter, morphology, and conversion of silver ions to silver powders were investigated. Silver powders with wrinkled surface and 100% conversion were prepared, and ground by using spiral jet milling and tumbling ball milling, respectively. Silver powders ground by using spiral jet milling had better size distribution, higher tap density, and corrugated surface, the tap density of silver powders ground by using spiral jet milling was 6.52 g cm–3. The silver powders were used to prepare front contact pastes of silicon solar cells, the aspect ratio of printed gridlines was 0.34.

Probabilistic Carbonation Simulations in Concrete Based on Marble Powder

The aim of this paper is the evaluation of concrete carbonation depth from a probabilistic analysis, focusing specifically on the study of the marble powder diameters randomness effect on the reinforced concrete carbonation. Monte Carlo simulations are realized under the assumption that the marble powder diameter (Dmp) is random variable with a log-normal probability distribution.

Analysis of Porosities in Nickel-Based Superalloys Powders

In this paper, we investigated the porosities and their formation mechanism in the nickel-base superalloy powders, which were prepared by electrode induction melting argon atomization and divided into four particle size ranges: d＜60μm, 60μm≤d＜120μm,120μm≤d＜180μm, and d≥180μm. Firstly, the distribution of porosities in the powder were observed by Zeiss electron microscope. Secondly, the number and size of porosities in different particle size range were counted. Finally, the formation mechanism of the porosity was analyzed in details. The results show that the porosities are mainly distributed at the edge and center of the powders, and the size increases with the increase of the powder size. the porosity varies from a few microns to dozens of microns. the biggest pore size in the powder is approximately 120μm.There are no obviously porosities found in powders when their diameters are less than 60μm. While the porosity appeared as the powder diameter is more than 60μm. In addition, the proportion of the powder with porosities also increases with increasing powder size. When powders size is more than 180μm, the proportion of the powder with porosities reached about 91%. In general, the formation of porosities in powders are mainly ascribed to two reasons. the first one is a portion of argon was enclosed by the metal films during the spheroidization; the second one is the metal droplets uneven shrinkage during the solidification.

Ultrasonic Preparation of Submicron Low Melting Point Alloy Powder

In order to study the preparation of low-melting alloy powder in phase change materials, three sets of control experiments were set up in this paper. To explore the effects of ultrasonic oscillation, ultrasonic atomization technology and rapid cooling had an effect on the particle size, surface morphology and powder shape of ultrasonic powder making. In the experiment, ultrasonic atomization, rapidly cooling ultrasonic atomization, and ultrasonic vibration generated powder were tested. The results showed that the surface of fog droplets generated by ultrasonic atomization was smooth, with distinct particles. The powder diameter was large, ranging from 20-60 μm. The surface of the powder obtained by ultrasonic shock existed an aggregation phenomenon. The powder diameter was small ranging from 5-10 μm. The ultrasonic atomized powder obtained by rapid cooling was mostly spherical with a smooth surface. After the screening, spherical powder with a diameter of 15-25 μm and the smooth surface could be obtained. The results showed that the particle diameter is small and uniform, while the uneven surface was difficult to eliminate. The experimental conditions of rapid cooling were favorable for the smoothness of the particle surface and the roundness of powder shape. Spherical powder with a diameter of 15-25 μm can be obtained by screening the rapidly cooled powder after ultrasonic atomization. Different experimental conditions and technological approach can produce high-performance low melting point alloy powder.

ANALISIS KADAR KAFEIN DALAM MINUMAN KOPI KHOP ACEH DENGAN METODE SPEKTROSKOPIK

In addition of being dubbed as the city of "Serambi Mekah", Aceh is also famous as the city of "Thousand Coffee Shops". One of coffee dish that attracts consumers' is khop coffee (read: kopi khop) because it is served with a glass dish upside down. The khop coffee, a typical coffee drink from Meulaboh, West Aceh Regency, is served by reversing the glass that has been filled with coarse coffee powder on top of the pan. Therefore, it is deemed necessary to conduct a special study on the analysis of unique taste-determining compounds in khop coffee to elevate the local wisdom of the Acehnese to the scientific region. The aim of this study was to determine the concentration of caffeine compounds of khop coffee due to the modification of coffee powder diameter by using the thin layer chromatography (TLC) method and UV-Vis spectrophotometry. This study used four types of samples with diameter variations coffee, namely original, fine, medium, and coarse. The four samples were extracted with boiling hot water according to the same conditions when the bartender served it (90 °C) followed by liquid-liquid extraction using chloroform solvent. Dry extract was analyzed by using TLC followed by a UV-Vis spectrometer. The results showed that the concentrations of original, fine, medium, and coarse coffee were respectively 57.85%; 17.61%; 1.29%; and 0.83%.

Pakan diameter berbeda bagi pertumbuhan benih sidat (Anguilla sp)

The objective of research was to establish the effect of different powder diameter on growth, efficiency value and daily consumption of eel seed. This research was conducted at the Laboratory of Aquaculture Technology, Faculty of Fisheries and Marine Sciences Sam Ratulangi University. Experimental design used was Complete Randomized Design with four treatments, each with three replication. Variables analysed consisted of relative growth, specific growth rate, feed efficiency value and daily comsumption. Results showed that treatment A with poder diameter of 0.125 mm displayed the best relative growth (105.356%), Specific growth (1.29%), feed efficiency value (6,431%), and daily consumption (0.813%). AS conclusion, feed with diameter 0.125 mm was utilized effectively by eel seed. Keywords: relative growth, specific growth rate, feed efficiency value. and daily comsumption, Anguilla sp

Study on the Influence Factors of Desilication in Bioleaching by B. Mucilaginosus

Bioleaching is an environmental friendly technology with many potential advantages such as few pollution and low energy requirement. The factors which affected the silicate-dissolving ability of Bacillus mucilaginosus Lv1-2on illite were investigated. The results showed that the optimum inoculum amount was 2%.The best carbon source and nitrogen source were glucose and (NH4)2SO4respectively. The silicon dissolution increased with the powder diameter decreased. The optimal temperature and shaking speed were 30°C and 220 rpm. The proper conditions were consistent with that of the growth of the strain,which confirmed that the strain played an important role in bioleaching.

Use of Liquid Film Evaporation in Biporous Media to Achieve High Heat Flux Over Large Areas

Boiling characteristics of three biporous and one monoporous sintered wick are tested. The monoporous wick has the same wick thickness as a comparable biporous wick. Diameters of the clusters of the comparable biporous wick are equal to the powder diameter of the monoporous wick. A second biporous wick has the same configuration as the first, but is sintered in a thicker layer. The third biporous wick that is tested has smaller cluster sizes then the first two. All three biporous wicks have clusters sintered from powder with the same size distribution. The results demonstrate the advantages of a biporous capillary structure. All biporous wicks reached higher critical heat flux (CHF) then the monoporous wick. Experiments show that larger clusters are better than smaller. Comparing two different wick thicknesses, we can see that even though there is a dryout region inside the thick wick, it is still able to continuously remove heat at constant superheat. No sudden changes in superheat are seen. This process of heat removal is not possible with the thin wick. The working fluid in all runs is methanol. 4-mm thick wick with powder diameter ranging from 53 to 63 microns and cluster diameter ranging from 500 to 707microns is able to remove 377W/cm2 at temperature difference 110°C. A partial pressure inside the test chamber at this heat flux is 0.68atm and the interface temperature 167°C.