Silicon carbide ceramic thermocouple protection tube and preparation method thereof

A silicon carbide ceramic and thermocouple technology, applied in the field of engineering ceramic materials, can solve the problems of complex structure, uneven drying shrinkage, and key technical data not yet disclosed.

Inactive Publication Date: 2014-04-23
SHANGHAI INST OF CERAMIC CHEM & TECH CHINESE ACAD OF SCI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the mold design of the extrusion section after sealing is not given
Moreover, the front piston is connected to the extruder piston, and the structure is relatively complicated. At the same time, such a sealing design cannot visually observe the sealing effect
[0012] U.S. invention patents US4923655, US5112544, US5043116, etc., have given a kind of one-end sealing process of ceramic extruded blanks, which are sealed by organic foam plugging and slurry impregnation. This process uses extruded through-hole blanks The body pipe is used as the base to seal the end of the pipe body, and the performance of the slurry needs to be exactly the same as that of the body, and there are problems of uneven drying shrinkage and easy cracking during sintering
[0013] US invention patent US5227105, using B 4 C-C is a sintering aid. Through a series of continuous production processes such as extrusion, drying, debonding and sintering, a through-hole silicon carbide ceramic pipe is prepared, and a silicon carbide thermocouple protection tube with one end sealed at one end is commercially produced, but No patent reports in this area have been seen yet, and some key technical information has not yet been made public

Method used

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  • Silicon carbide ceramic thermocouple protection tube and preparation method thereof

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preparation example Construction

[0097] A second aspect of the present invention provides a method for preparing the silicon carbide ceramic thermocouple protection tube, which includes the following steps:

[0098] Provide the raw material described in the present invention;

[0099] The raw material is extruded to obtain a tube body of a silicon carbide ceramic thermocouple protection tube;

[0100] The tube body is sintered at a high temperature to obtain the silicon carbide ceramic thermocouple protection tube.

[0101] mold

[0102] The third aspect of the present invention provides a mold for extrusion molding of a ceramic thermocouple protection tube, the mold has a sealing end.

[0103] In a specific embodiment of the present invention, the extrusion sealing mold is mainly composed of (I) extrusion core, (II) connecting piece, (III) outer mold sleeve, and (IV) sealing piece.

[0104] In a specific embodiment, the extrusion core (I) has air holes in the middle of the horizontal and vertical directio...

Embodiment approach

[0115] The method includes process steps such as batching, extrusion molding, drying, heat treatment and high-temperature sintering:

[0116] (1) Mix the silicon carbide powder, the second phase powder and the sintering aid evenly, stir evenly, dry and sieve to obtain the mixed powder.

[0117] The average particle size of the silicon carbide powder can be 0.2-5.0 μm, and the optimized average particle size is 0.5-1.5 μm.

[0118] The second phase powder can be MoSi 2 , BN, TiB 2 , ZrB 2 Or its composite powder, etc., its content is 0-15wt%, and the optimized content is 5-10wt%.

[0119] The sintering aid may include B 4 C-C, C-B system, where C can be introduced in the form of powder or cracking of organic polymers.

[0120] said B 4 The content of C or B is 0-1.5wt%, and the optimized content is 0.4-1.0wt%. The content of C is 0-6wt%, and the optimized content is 1.0-4.0wt%.

[0121] (2) Add plasticizer, water, lubricant, dispersant, defoamer, etc. to the mixed powde...

Embodiment 1

[0146] SiC powder with an average particle size of 0.5 μm and 0.4wt% B 4 C powder and 1.0wt% carbon black are uniformly mixed, stirred evenly, dried and sieved to obtain a mixed powder. Add plasticizer, water, lubricant, dispersant, defoamer, etc. to the mixed powder and stir evenly, and carry out vacuum mud refining in the mixer for aging treatment. Put the mud on the vacuum extruder and install the extrusion die for extrusion molding. When the pipe body is stable, install the sealing piece. Wherein the diameter of the ventilation hole is 0.5 mm, the diameter of the hemispherical plastic plug is 1.5 mm, and the diameter of the mud discharge hole is 1.0 mm. The outer diameter of the extruded pipe is 15mm, the wall thickness is 1.5mm, the surface is smooth, and the sealing is uniform. The extruded silicon carbide thermocouple protection sleeve body is dried and heat-treated at high temperature to obtain silicon carbide ceramics. The density reaches 96.2% T.D, the thermal con...

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Abstract

The invention provides a silicon carbide ceramic thermocouple protection tube. The material of the silicon carbide ceramic thermocouple protection tube is prepared from the following raw materials by extrusion moulding and high-temperature sintering: submicron-order silicon carbide powder, the second-phase powder accounting for 0-15% of the weight of the submicron-order silicon carbide powder and a proper amount of sintering aid, wherein the second-phase powder is MoSi2, BN, TiB2, ZrB2 or composite powder thereof; and the sintering aid adopts a solid-phase sintering aid system selected from B4C-C system and C-B system.

Description

technical field [0001] The invention relates to a silicon carbide ceramic and a preparation method thereof, and more precisely relates to the preparation of a silicon carbide ceramic thermocouple protection tube by an extrusion molding process. The invention belongs to the technical field of engineering ceramic materials. Background technique [0002] Thermocouples are the most widely used temperature sensors and play an important role in various industrial fields. However, the long-term stability, service life and other performance indicators of the thermocouple directly depend on the performance of the protection tube material. Especially in modern industry, temperature measurement in various harsh environments such as high temperature thermal shock, acid and alkali corrosion, molten metal corrosion, strong oxidizing or reducing atmosphere is more and more common, and the development of long-life, cost-effective thermocouple protection tubes has always been It is one of ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C04B35/565C04B35/622
Inventor 闫永杰黄政仁刘学建陈忠明
Owner SHANGHAI INST OF CERAMIC CHEM & TECH CHINESE ACAD OF SCI
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