Production method of ultra-high-temp. electrothermal ceramic heating body

Abstract

The invention relates to the method for manufacturing the ultra high temperature ceramics heating unit heated by electricity. Using the high temperature solid phase reaction generate LaCrO3 basis material. Adulterating microelement to change the agglomeration shrinkage and using modeling technique with one stroke in equal static pressure produce the ceramics heating unit. The invention overcomes the shortcoming existed in the LaCrO3 basis material made by using the wet process in liquid phase. Also it solves the issue of the agglomeration consistency between different ingredient of La1-xMxCrO3, and the issue of obtaining a intergrated body between different ingredients by using modeling technique with one stroke, as well as the issue of completing once agglomeration at same temperature for each blank of the heating unit.

Description

1. Technical field: [0001] The invention relates to a method for manufacturing an ultra-high temperature electric heating ceramic heating element, which belongs to the field of electric heating heating materials. 2. Background technology: [0002] The main characteristics of the electric heating element are: very high working temperature, allowable surface power, anti-oxidation and anti-corrosion ability and service life. Traditional anti-oxidation heating elements include: Ni-Cr, Fe-Cr-Al, SiC, MoSi 2 . The maximum service temperature of Ni-Cr, Fe-Cr-Al does not exceed 1200°C, SiC does not exceed 1450°C, MoSi 2 Not exceeding 1700°C. The oxidation phenomenon of SiC will be accelerated when the service temperature exceeds 1450°C, and the electrical properties of intermittent use will have obvious aging phenomenon. MoSi 2 When used for a long time in the temperature range of 400-700 ℃, low-level oxidation will occur and be destroyed. [0003] Oxide ceramic materials used ...

AI Technical Summary

Problems solved by technology

[0007] There are two types of heating element molding: one is to extrude the material of the same composition into a tube shape, and then process the middle part into a heating element blank with a thinner diameter or directly isostatically press it into a heating element blank with a thinner middle and thicker ends , it is difficult to ensure a high resistance value ratio between the hot end and the cold end after the two kinds of heating element blanks are sintered into the heating element. The ratio depends on the wall thickness of the heating element at the hot end and the cold end. In order to ensure the strength of the heating element, The ratio is generally less than 2, and it is difficult to improve the heating efficiency of a heating element of this shape; the other is to extrude the materials used as the cold end and the hot end into a tube shape, sinter them separately and then weld them together, and the welds must leave interfaces of different degrees Defects, thus affecting the service life of the heating element

[0008] The sintering technology of the heating element is: horizontal sintering in the air, the sintering temperature is to sinter the hot end material at 1750°C, sinter the cold end material at 1600-1750°C, and then weld the two materials together as required to complete the heating element. Production; one is firing at a temperature of 1350-1500 ° C, both methods have disadvantages, the former one is sintered at too high a temperature, and is sintered separately, and thermal stress will inevitably be left after welding, which will affect the use of components ;The sintering temperature of the latter is low, and when the element is used at a furnace temperature of 1750°C, secondary sintering will occur. At this time, the electrical properties of the heating element will change, which will affect the parameters of the electric furnace control system and cause fluctuations in the furnace temperature.

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