Induction heating, radio-frequency

Continuous production of fullerenes was possible by pyrolysis of acetylene vapor in a radio-frequency induction heated cylinder of glassy polymeric carbon having multiple holes through which the gas mixture passes [44]. Fullerene production is seen at temperatures not exceeding 1500 K. The yield of fullerenes, however, generated by this method is less than 1%. A more efficient synthesis (up to 4.1% yield) was carried out in an inductively coupled radio-frequency thermal plasma reactor [45]. 

In the evaporation method, a film is deposited by the condensation of the vapor on a substrate, which is maintained at a lower temperature than that of the vapor. All metals vaporize when heated to sufficient temperatures. Several methods, such as resistive, inductive (or radio frequency), electron bombardment (e-beam), or laser heating, can be used to attain these temperatures, according to the metal to deposit. 

The Curie-point flash pyrolyser was originated by Szymanski et al. [522], initially developed by Simon et al. [523] and later improved [511]. A Curie-point system (Fig. 2.24) can heat a ferromagnetic metal wire inductively with radio frequencies to the pyrolysis temperature in milliseconds. The final temperature is well characterised and reproducible. The alloy of the ferromagnetic material used achieves control of the pyrolysis temperature in a Curie-point instrument. Curie-point reference values are alumel 154.2°C, nickel 355.3°C, Perkalloy 596°C, iron 780° C, Hisat-50 1000°C. A set of six certified and traceable Curie temperature materials is available (ICTAC/TAI). 

A plasma of electrons, ions, and neutrals produced in gas flowing through concentric tubes is maintained and heated to 5000 to 8000 K by inductive coupling to a high (radio) frequency... 

Pulse-mode pyrolyzers include resistively-heated electrical filaments or ribbons and radio frequency induction-heated wires [841,842,846,848,849]. The filament or ribbon-type pyrolyzers are simple to construct. Figure 8.45, and typically consist of an inert wire or ribbon (Pt or Pt-Rh alloy) connected to a high-current power supply. Samples soluble in a volatile solvent are applied to the fileutent as a thin film. Insoluble materials are placed in a crucible or quartz tube, heated by a basket-lilce shaped or helical wound filiunent. The coated filament is contained within a low dead volume chamber through which the carrier gas flows, sweeping the pyrolysis products onto the column. The surface temperatui of the filament is raised rapidly from ambient temperature to He equilibrium pyrolysis temperature. This... 

The Czochralski Technique. Pulling from the melt is known as the Czochralski technique. Purified material is held just above the melting point in a cmcible, usually of Pt or Ir, most often powered by radio-frequency induction heating coupled into the wall of the crucible. The temperature is controlled by a thermocouple or a radiation pyrometer. A rotating seed crystal is touched to the melt surface and is slowly withdrawn as the molten material solidifies onto the seed. Temperature control is used to widen the crystal to the desired diameter. A typical rotation rate is 30 rpm and a typical withdrawal rate, 1—3 cm/h. Very large, eg, kilogram-sized crystals can be grown. 

Radio-frequency induction heated wires (Curie-point pyrolyzers)... 

The substrate is mounted on a graphite susceptor (usually SiC-coated) and a radio frequency (rf) field is used to inductively heat the susceptor. 

The p-type manganese silicide sintered element used ia this investigation were formed in the shape of sintered (7mm in diameter) cylindrical pellets by means of the processing as shown in Pig.l. The raw materials of Mn(4ISI) and Si(4N) were mixed in the ratio of (Mn Si = 1 1.73) and directly melted by Radio-Frequency induction heating system in a graphite crucible under vacuum. The small amoimt of Ge was added in the raw material as a dopant. In order to... 

Inductively Coupled Plasma (ICP) - ASTM D5185 In the ICP method, argon gas is passed through a radio frequency induction coil and heated to a temperature of 8000-10,000 K, producing a plasma. The oil sample, diluted by a low viscosity solvent such as xylene or kerosene, is nebulized and borne by the argon gas carrier into the centre of the plasma torch. The high temperatures excite the metal atoms. 

Electrical, e.g. ultrasonic, high-frequency/radio frequency, impulse, induction sealing. Basically a modification of the heat seal process. 

Inductively coupled plasma (ICP) reactors (Fig. 20a) are particularly attractive because their design is relatively simpler and they are easily scaleable to large diameter substrates [84, 85]. In ICPs, the plasma is excited in a cylindrical chamber (r, 2,0) by a solenoidal or planar (stovetop-type) coil powered at radio frequencies, for example 13.56 MHz. The coil current induces a time-varying magnetic field which in turn induces an azimuthal (in the 0-direction) electric field that couples power to the plasma, i.e., heats the plasma electrons. For common excitation frequencies (less than the plasma frequency), the electromagnetic fields are absorbed by the plasma within the skin depth. For typical conditions, fields penetrate a few cm into the plasma. The power is deposited non-uniformly in the shape of a toroid (see also Fig. 

Direct resistance heating most simply is effected in a cold wall reactor. For such a reactor, the typically employed form of input energy is radio frequency (Rf) induction heating of a conducting substrate support, known as a susceptor. Typical susceptor... 

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