![]() With regard to moisture, it is the same as in the case of hydrogen. Nitrogen gas reacts with silicon carbide, forming silicon nitride when the temperature exceeds 1400℃, and this shortens the service life. It is recommended that the surface load shall be decreased as much as possible. It is recommended that it shall be used at a temperature of less than 1300℃ in the furnace chamber. The service life, however, depends very much on the intensity of moisture of the gas. It is important to raise the temperature after purging moisture sufficiently at a low temperature when initiating a new furnace or starting to use one after a long suspension.ĮREMA’s resistance increases rapidly and its mechanical strength deteriorates quickly if the temperature exceeds 1350℃ in a hydrogen gas atmosphere. Heater’s lifespan is sometimes cut to less than one fifth of the expected lifespan under dry open-air conditions. In any atmosphere, it is recommended to decrease the surface load as much as possible. The correct application of coating increases EREMA’s service life. Tokai Konetsu Kogyo has therefore developed special protective coatings (protective films) for special atmosphere or corrosive substances in order to prevent EREMA aging. Similarly, caution is necessary to prevent the reaction of EREMA heating elements with various chemical substances emitted from processed materials during heating operation. ![]() In recent years, cases requiring furnace atmosphere control have been increasing and caution must be exercised for EREMA use in various atmospheres. It varies depending on (1) Operation Temperature (2) Surface Loading (3) Atmospheres and Materials to be Processed (4) Energizing Method (5) Electrical Connection (6) Installation Method of Heating Elements.ĭetailed explanations are given as follows.ĮFFECTS OF ATMOSPHERE CONDITIONS ON EREMA HEATING ELEMENTS ![]() the life of heating elements, varies greatly according to the following application conditions. The reason is that, reaching an approximate threefold increase, the variation in each element’s resistance becomes greater and heat distribution per one element worsens, causing inefficient temperature distribution in the furnace chamber.Īlso, silicon carbide heating elements, when coming to the end of their life, cause not only resistance increase but changes in apparent porosity and fracture damage by deterioration in strength, so caution must be exercised.Įspecially Types SG and SGR have a tendency to cause meltdown when approaching the end of their lives.Ĭaution must be exercised, as the time required for electric resistance to increase three times the initial value i.e. (The life of SG and SGR lasts until resistance reaches 1.7 times the original value). For Types E, E-DV, F, U and M, the service life limit is suggested to be when its resistance increases to about 3 times the initial resistance. General variation in electrical resistance is shown in Fig. Fig 3 ) Increase in Resistance (Type E, E-DV and F)
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