Sintering Thermo

A. 1,4-Diphenyl-5-amino-l,2,3-triazole. A 500-ml. three-necked flask is equipped with a sealed stirrer, a thermometer well, and a dropping funnel which is protected by a drying tube and has a pressure-equalizing side arm. A mixture of 35.7 g. (0.3 mole) of phenyl azide (Note 1) and 38.6 g. (0.33 mole) of phenylacetonitrile (Note 2) is placed in the flask. The flask is immersed in an ice-water mixture contained in a 1-gal. Thermos flask. After the reaction mixture has cooled to about 2°, a solution of 24.3 g. (0.45 mole) of sodium methoxide (Note 3) in 150 ml. of absolute ethanol is added dropwise during the course of 2 hours. The reaction mixture is then stirred at 2-5° in the ice-water bath for a period of 48 hours (Note 4). After the cooling bath has been removed and the flask allowed to warm spontaneously to room temperature, the mixture is filtered by suction on a sintered glass funnel, and the col-... 

For instance, conductometric transduction has been used for determination of an atrazine herbicide in the concentration range 4.6-231.8 mM [165]. A sintered glass frit was used as the support for the MIP film prepared by thermo-radical polymerization. However, both the response time of 30 min and the chemosensor recovery time of 12 h were long. For better performance, the MIP film was prepared by photo-radical co-polymerization of a chloroform solution, which contained tri (ethylene glycol)dimethacrylate (TEGDMA), MAA, and oligourethane acrylate, sandwiched between two quartz slides (Table 6). 

Some of the flame volatile sodium is dissolved in the vitrified silicate ash particles before deposition and an additional amount of sodium is transferred from the sulphate to silicate phases during sintering. The reaction between sodium sulphate and silicates at ash sintering temperatures has been monitored by thermo-gravimetric measurements. Some of the results are given in Table IV. 

Compounds containing fillers are usually more sensitive to thermal decomposition due to the acceleration of thermo-oxidative reactions by a number of additives at elevated temperatures. Fillers could allow sintering compounds at lower temperatures due to an increase in the conductivity of the part. For example, a metal-filled PTFE compound (steel, lead, or bronze) has a significantly higher thermal conductivity than PTFE, which leads to rapid heating of the part. 

High-temperature applications of perovskite-type membrane reactors require improved material performances and operational stability. The reactor microstruc-ture and architecture controls were found to be crucial for thermo-mechanical integrity and oxygen permeation kinetics. A multilayer reactor was developed, using second-phase particles to control its microstructure and a co-sintering process to control its architecture. 

Figure 5.3. Apparatus (thermo-cell) for measuring transport of electricity in the presence of temperature gradient. C, coulometer A, ammeter B, battery K, key Ej, Ej, electrodes D, sintered glass disc 1, thermostat maintained at temperature T] 11, thermostat maintained at temperature Tn.

Q. Wei, et al., "High Temperature Uniaxial Creep Behavior of a Sintered In Situ Reinforced Silicon Nitride Ceramics", Ceramic Engineering Science Proceedings, ed. E. Usttlndag and G. Fischman, 20(3), 1999, The American Ceramic Society Westerville, OH, 463-470 G. Ziegler, "Thermo-Mechanical Properties of Silicon Nitride and Their Dependence on Microstructure", Mat. Sci. Forum, 47, 162-203 (1989)... 

Sintered molybdenum (thermal conductivity around 115 W/mK) for nozzle casings and tips in applications up to 360 °C (Figure 4.5b), and for melts with an abrasive action (five times greater durability than that of copper/beryllium alloys). After ion treatment (thermo-implantation) the durability of molybdenum sinters is increased by many times. Molybdenum sinters are brittle in places where there is a notch, e.g., the thermocouple groove ... 

A honeycomb packing can also be assembled of thermo-pressed plates, as presented in Fig. 48. Using plates of sintered plastics, for example sintered PVC, it is possible to obtain a packing able to operate at very low liquid supeificml velocity with practically ftilly wetted packing surface area [62-64, 145- 147]. 

The extremely high melting point and the low self-diffusion coefficient make these ceramics very difficult to sinter to full density temperatures above 2000°C and the application of pressure are necessary conditions. However these processing parameters lead to coarse microstructures, with mean grain size of the order of 20 pm and trapped porosity, all features which prevent the achievement of the full potential of the thermo-mechanical properties of UHTCs. 

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