High-frequency induction

Vacuum and Atmosphere Melting. A coreless high frequency induction furnace is enclosed in a container or tank which can be either evacuated or filled with a gaseous atmosphere of any desired composition or pressure. Provision is made for additions to the melt, and tilting the furnace to pour its contents into an ingot mold also enclosed in the tank or container without disturbing the vacuum or atmosphere in the tank (Fig. 2). 

Recently, attention has been directed to a study of the problem of grooving corrosion in line-pipe steel welded by high frequency induction or electric resistance welding. In sea water, it seems to be related to high sulphur content in the weld zone, the type of environment, its temperature and velocity The importance of sulphur is significant since Drodten and... 

Thermal CVD requires high temperature, generally from 800 to 2000°C, which can be generated by resistance heating, high-frequency induction, radiant heating, hot plate heating, or any combination of these. Thermal CVD can be divided into two basic systems known as hot-wall reactor and cold-wall reactor (these can be either horizontal or vertical). 

Welding is possible for certain grades by the thermal processes, high frequencies, induction and by ultrasound. The strength of the joints can be 10-40% of the PMMA used. Gluing generally gives better results. 

In the Watertown Arsenal method, the metal is melted in batch lots of the required weight in high-frequency induction furnaces and poured into a horizontally mounted mold rotating at 1300rpm while it is cooled on the outside with water. The mold is made of heavy cast iron and machined inside to the desired shape of the exterior of the gun to be produced. The finished casting has a hollow core and can be easily bored out to the desired internal diam of the gun(Ref 3)(See also Ref 2a)... 

Kuwae et al. [138] have described a rapid determination of mercury in soils by high-frequency induction heating (rf) followed by cold vapour atomic absorption spectrometry. The mercury released from the sample is absorbed in stannous chloride-hydroxylamine prior to atomic absorption spectrometry. Recovery of 99.4 to 99.8% mercury was obtained by this method from portions of sample containing between 0.025-0.15 p,g of mercury. 

The work of laboratories of moderate resources is based upon resistance furnace methods. More elaborate methods, such as high-frequency induction, cooled-crucible arc, electron bombardment, or mirror furnaces, with their resulting higher temperature ranges are financially beyond the reach of these laboratories. 

Boulos, M. I. Mostaghimi, J. Proulx, P. In High Frequency Induction Plasma Sherbrooke, 1989. 

In high-frequency induction sealing a metallic component is located at the point of joining in such a manner as not to inhibit the flow of molten material the inset is designed to ensure a flow of material sufficient to give a seal of the strength required. The method is used mainly for the assembly of moulded components, or for the sealing of plastic bottles in instances where a tamper-evident hermetic seal is needed. 

Modern equipment for continuous production normally includes high-frequency induction generators, which are switched electronically, and speeds of hundreds of heating cycles per minute are becoming commonplace. 

Curie-point pyrolyzer (high frequency inductive heating of a ferromagnetic carrier). 

Electric resistance weld pipe is made from strip in coil form. After being uncoiled, flat strip is progressively rounded as it passes through a series of vertical and horizontal forming rolls before welding. Small-diameter pipe is welded by the high frequency induction method and medium-diameter... 

B3. Brewer, L., The Use of Laboratory, High Frequency Induction Furnaces. UCRL—653 (April, 1950). 

The commonly used RF frequencies in Curie point pyrolysers are 400 to 1000 kHz, and the power outputs range from 100 to 1500 watts. The rate of temperature rise depends on the conductor mass and specific heat, as well as on the power consumption of the ferromagnetic conductor. This power consumption per unit surface is related to the amount of heat generated by the conductor and implicitly to the temperature. The power consumption per unit surface N (cal cm sec ) of a ferromagnetic conductor located along the axis inside a high frequency induction coil is given by the formula ... 

The temperature increase in time is fairly abrupt, as shown in Figure 4.2.2a for an iron wire in a high frequency induction field of 382 Oe and 1.2 MHz and in Figure 4.2.2b for an iron wire in a high frequency induction field of 1170 Oe and 480 kHz [8]. 

Typical application fields are casting molds for molded vanadium components, crucibles for high frequency induction furnaces and substrates for integrated circuits. In nuclear reactor technology beryllium oxide is mixed with nuclear fuel as a moderator for fast neutrons. 

Use (Unstabilized) Production of piezoelectric crystals, high-frequency induction coils, colored ceramic glazes, special glasses, source of zirconium metal, heat-resistant fibers, (hydrous) odor absorbent, to cure dermatitis caused by poison ivy. (Stabilized with CaO refractory furnace linings, crucibles, solid electrolyte for batteries operating at high temperature. 

George P et al (2003) High-frequency inductance measurements and performance projections made for cusp-field single-pole heads. IEEE Trans Magn 39 1949-1954... 

Parsons et al. [62] improved the nitrogen determination techniques and reduced the analysis time to 15 min. In their experiments, the weight of organic and inorganic samples was 1-10 mg and that of blood samples was 10—20 mg. A sample was mixed with 0.8 g of silver permanganate, a small amount of copper oxide was added and the mixture was burned for 30 sec in a high-frequency induction furnace. 

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