Crucible compositions

Figure 5.10 DTA-GC curves for screening the oxidation activity of C 0 catalyst [18]. DTA 250 aV, 20°Cmin cooling rate, 5 min reference materiaL empty crucible composition of reactive gases, C0-02-N2(2.7 5 92.3) flow-rate, 35 ml min mass of CuO, 1.95 mg. GC-TCDj bridge current, 140 mA cell temperature, 60 "C GC columns in series containing 401 organic support and 5A molecular sieve carrier gas, Ar at 20 ml min . Model reaction screening oxidation activity of catalyst, CO +50, CO2 the conversion rate(%) of CO to CO, was obtained from the CO peak area on the GC trace...

DTA— 100pV heating rate, 10°Cmin" isothermal reaction temperatures, 400, 350, 300 250 °C reference material, empty crucible composition of reaction gases, volume ratio (%) of C0 02 N2= 2.7 5 92.3 flow-rate,... 

Glass in the form of fibres is relatively inexpensive and is the principal form of reinforcement used in plastics. The fibres are produced by drawing off continuous strands of glass from an orifice in the base of an electrically heated platinum crucible which contains the molten glass. The earliest successful glass reinforcement had a calcium-alumina borosilicate composition developed... 

As an example, consider the following. Suppose we have a crucible half-filled with a powder. We now fill the crucible with another powder of different composition and then heat the filled crucible. Any solid state reaction which does occur can only do so at the boundary of the two layers of powders. If the reaction is A -t- B = AB, then we find that the reaction product, which is also a solid, forms as a phase boundary between the two layers. The same condition exists in a solid state reaction between two crystalline particles having differing compositions. That is, they can only react at the interface of each particle. This is illustrated in the following diagram, which is a model of how the components react through a phase boundary ... 

The procedure involves obtaining a fuU crucible of melt whose composition mirrors that of the crysted we wish to grow. We then lower the crucible containing the melt through a baffled zone within the furnace... 

Synthesis of sulfo-selenide Chevrel phases Phases ofM Mo x xSex composition (M = Cr, Mn) were prepared by the reaction of stoichiometric mixtures of MoS2 and MoSe2 binary powders with Mo and Cr, or Mn, metallic powders (Mantjour-Billah and Chevrel 2004). The mixtures were pressed into pellets and then (inside an alumina crucible) sealed in evacuated silica tubes. After heating to 800°C and then to 1000°C for 24 hours, two further grinding and annealing (at 1000°C) treatments were performed. Powder X-ray diffraction methods were used to study the solid solutions, the trend of the lattice parameters, etc. 

The tests involved mixing known amounts of silver chloride with sodium hydroxide. The silver chloride was precipitated from a simulated anolyte solution with composition similar to that expected after the anolyte solution has been passed through the polishing circuit of the IRS. Metals in the simulated anolyte solution included Fe, Al, and Cu. The silver chloride/sodium hydroxide mixture was placed in a nickel crucible and then into a furnace heated to 600°C. After termination of the reaction, the crucible contents were quenched in water, washed out with water, and filtered. A silver mass balance was then performed. 

For dehydration, place the platinum (nickel) crucible with the prepared salt ( 5 g) into a test tube with a standard ground-glass joint (Fig. 63). Preliminarily weigh the crucible and the salt with an accuracy up to 0.01 g. Connect the test tube to a vacuum system. Evacuate it (10- mmHg) first at room temperature during 10-20 min, and then at 150 °C on an oil bath or a bath with Wood s alloy. Dehydrate the substance up to a constant mass. Calculate the composition of the product according to the change in its mass. 

Put a small amount of the magnesium chloride hexahydrate into a crucible and roast it. What is observed Decompose the salt completely. How can you see that this has occurred Cool the crucible and add 1-2 ml of water. What is the composition of the substance that has not dissolved in the water ... 

Preparation of Potassium Chromate. (Perform one experiment on each table.) Melt a mixture of 1 g of potassium carbonate, 1 gof potassium hydroxide, and 2 g of potassium nitrate in an iron crucible by heating with the flame of a burner. While stirring the melt with an iron wire, introduce 1 g of finely comminuted chromite or -0.8 g of chromium oxide into the crucible. Roast the mixture for 5-10 minutes on a blowpipe. Treat the cooled melt with water. Filter the solution and evaporate it until a crystalline film appears. What is the composition of the formed crystals Why was potassium carbonate introduced into the reaction Write the equation of the reaction. 

Sapphire. —To produce a fine oriental blue color, one must employ very white strass, and very pure oxide of cobalt. This composition, put into a luted Hessian crucible, should remain thirty hours in the fire. Tho... 

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