In the production of shaped and large ceramic articles, the method of vibration pressing has been proved to be very useful [1][2][3]. But the extensive use of this method is being delayed by the limited amount of experimental data available, most of which are difficult to compare, since they have been obtained on various designs of vibropress.Thus the authors of 14, 5] used equipment with the vibrator situated in the upper force plunger.In view of the elastic properties of rigid bodies and the friction between the particles of powder, the energy of the oscillations from the vibrator at depth is rapidly attenuated. Densification according to such a scheme occurs only from the surface in a way similar to the process of vibration tamping. According to [6] equipment has been used with the placement of the matrix and the lower plunger on the vibration table. With this method the entire volume of material is vibrated, regardless of the height of the article, but it is possible that with the application of the static pressure, the body being shaped will be compressed, and densification will be incomplete. This effect can be significantly reduced by using a "floating matrix" [7]. However, with an increase in the density of the greenware there is an increase in the bonding of the powder with the mold walls, and the effect of the floating matrix disappears.Equipment is available in which, with a top force plunger, only the lower plunger is subjected to oscillation, while the matrix is attached in the immobile condition [8], which enables us to obtain a more uniform density from top to bottom of the article.In certain equipment [9] the upper plunger rests on a fixed foundation. However, this solution is unsuccessful since the amplitude of the oscillations of the vibrating lower plunger is reduced in proportion to the increase in the static pressure.In order to maintain the amplitude unchanged the load-lifting capacity of the vibrating table should be not less than the force of pressing, which exceeds by many times the mass of the vibrating bodies.In a number of design projects the force plunger rests directly on the vibrotable.In this design the amplitude of the oscillations does not depend on the pressing force.In order to reduce the possibility of compressing the body the upper force plunger is sprung, and the oscillations of the vibrotable are converted into the vibroimpact schedule [!0].The disadvantages of all the above designs for vibropresses are their cumbersomeness, high metal and energy consumption, and the need to use special foundations, which restricts and delays their use under laboratory conditions. Therefore it has become necessary to design a new laboratory unit.The basis of the design was one with the force plunger resting on a vibrating platform consisting of a regular laboratory vibration table of the type 435A with an amplitude of up to 0.85 mm (without load) and a kinetic moment for the IV-36 vibrator of up to 54.8 N.cm. The plan of the assembled equipment is shown in Fig. i. The main part is the frame...
In Soviet industry, sodium sulfide is obtained in shaft furnaces by reducing sodium sulfate with coke in the range 850-1100~ according to the reaction Na2SO 4 + 4C = Na2S + CO 2 --48.5 kcal. The final product (melt at a temperature of 1000-1100~ upon discharge from the tapping hole, contains 65-700/0 * Na2S , 8-11% Na2SO4, and 5-8% Na2CO a.The short life of the chrome--magnesite lining in the shaft furnace in the zone used for reducing the sodium sulfide (not more than 9-10 days) causes a low utilization coefficient to be recorded for these furnaces, as well as significant material and labor outlay for production.Destruction of the chrome--magnesite refractory occurs as a result of the chemical corrosion, the variable action of the reducing and oxidizing atmospheres, and cooling of the first and second courses of the lining in the subtuyere zone with cold air sucked through the tuyeres. The temperature of the melt and gases is relatively low and does not have a decisive effect on the wear of the chrome--magnesite refractory.Previous investigations [1][2][3] showed that the chamotte (4490 A1203), high-alumina (75% A1203), dinas, magnesite, chrome--magnesite and chromite refractories are not stable in molten sodium sulfide. Graphite refractories possess a high resistance only when the melt contains not more than 10-15% sodium sulfate [4]. Note has been made of the resistance of specimens containing 67.5-90% A1203 and also specimens of standard electroeorundum and slag from the aluminothermic production of titanium, but these refractories have not been tested industrially.High-density spinel-containing refractory (open porosity 1-4.59o) was sdccessfully tested in a furnace for burning alkali stocks (combustion temperature 1100~The furnace campaign was 4 months. The refractory was in a good condition after the furnace had been stopped for repairs [5]. However, the wear of the spinelcontaining refractory tested in the form of a panel in the shaft furnace for producing sodium sulfide was 5-7 mm/day (against 11.9-15 ram/day for the other refractories studied), which is inadequate for use in the furnace lining [6]. Thus, of all the bricks tested the most interesting is corundum. * Here and subsequently, parts by weight are indicated.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.