CN113321509A - Corrosion-resistant vent pipe for fluoride glass active atmosphere treatment - Google Patents

Abstract

A corrosion-resistant breather pipe for fluoride glass active atmosphere treatment is prepared by mixing carbon powder and magnesium fluoride according to a certain proportion, and carrying out molding, vacuum sintering, corrosion and hot isostatic pressing sintering; the outer pipe wall of the vent pipe is made of glassy carbon, the inner pipe wall is made of high-density magnesium fluoride ceramic, and the middle layer of the inner pipe wall and the outer pipe wall is made of nano complex phase ceramic of carbon powder and magnesium fluoride. The outer wall of the breather pipe provided by the invention is made of glass carbon, so that the corrosion of perfluorinated glass melt can be effectively prevented; the inner pipe wall is made of magnesium fluoride ceramic, so that the corrosion of active fluoride gas can be effectively prevented; the middle layer is made of nano complex phase ceramic, and the strength and the fracture toughness of the vent pipe can be effectively improved. Therefore, the invention can greatly reduce the risks of corrosion and breakage of the vent pipe and introduction of impurities in the glass liquid in the fluoride glass active atmosphere treatment process.

Description

Corrosion-resistant vent pipe for fluoride glass active atmosphere treatment

The technical field is as follows:

the invention relates to the field of preparation of corrosion-resistant materials, in particular to a corrosion-resistant vent pipe for fluoride glass active atmosphere treatment.

Background art:

fluoride glass fibers due to extremely low theoretical losses (10)^-3dB/km), high damage threshold, low phonon energy and excellent mid-infrared spectrum performance, and has strong application prospect in military and civil use. In military applications, fluoride glass optical fibers are core components for optical-electrical countermeasure, space communication, and the like. For civil use, fluoride optical fibers are widely used in the fields of medical surgery, industrial processing, communication, autopilot, security, and the like. However, the loss of fluoride optical fiber is much higher than theoretical loss, especially in the vicinity of 2.7 μm, due to the presence of-OH groups and oxide nanoparticles in fluoride glass.

In order to solve the above problems, there is generally a reactive atmosphere treatment in the fluoride glass manufacturing process, i.e., a reactive CF is treated at a high temperature using a breather tube₄、SF₆、NF₃HF or F₂Gas is introduced into the glass melt to realize the deep removal of water and oxygen in the fluoride glass. However, metals, alloys and precious metals react with reactive fluoride gases at high temperatures, leading to the introduction of impurities and, in severe cases, to leakage. In addition, the breather tube end needs to be inserted into the glass melt, and fluoride glass melts can also attack metal, alloy and precious metal breather tubes. On the other hand, organic teflon or the like tubes are not suitable because they can withstand the high temperature at the time of glass melting, although they can withstand the reactive fluoride gas.

In view of the above, it is important to have a vent tube that is resistant to both reactive fluoride gases and attack by the glass melt, and also is resistant to high temperatures.

The invention content is as follows:

in order to solve the problems, the invention aims to provide a corrosion-resistant vent pipe for fluoride glass active atmosphere treatment, and solves the problem of low glass quality caused by the corrosion of the vent pipe in the fluoride glass active atmosphere treatment process.

In order to achieve the above object, the technical solution of the present invention is as follows:

the corrosion-resistant breather pipe for fluoride glass active atmosphere treatment is characterized by sequentially comprising an inner pipe wall, an intermediate layer and an outer pipe wall from inside to outside, wherein the outer pipe wall is made of a glassy carbon material, the inner pipe wall is made of a magnesium fluoride (MgF2) ceramic material, and the intermediate layer is made of a graphite and MgF2 nano composite ceramic material.

The preparation method of the corrosion-resistant vent pipe is characterized by comprising the following steps of:

step 1), uniformly mixing nano carbon powder A and nano MgF2 powder B according to a proportion under ball milling to obtain powder, wherein the molar ratio of A (A + B) is 45-60%;

step 2), obtaining a cylindrical ventilation pipe biscuit of graphite and MgF2 nano complex phase ceramic by dry pressing and cold isostatic pressing the powder, and preparing a semi-compact ventilation pipe by vacuum sintering;

step 3), the semi-compact vent pipe is etched in two steps: firstly, introducing nitrogen trifluoride (NF3) into a semi-compact ventilation pipe for 1-60 min, and reacting NF3 gas with carbon to obtain an MgF2 ceramic inner wall; secondly, sealing two ends of the vent pipe, inserting the vent pipe into fluoride glass melt, maintaining for 1-240 min, and reacting MgF2 with perfluorinated glass melt to obtain a glass carbon outer wall;

and 4), sintering the vent pipe through hot isostatic pressing to obtain the corrosion-resistant vent pipe.

The aeration time is 20-40 min. The maintaining time is 20-100 min.

Compared with the prior art, the invention has the following technical effects:

compared with the prior breather pipe, the breather pipe for treating the fluoride glass active atmosphere is difficult to resist the corrosion of fluoride glass melt and fluoride active atmosphere at the same time at high temperature.

The prior breather pipe can not resist active atmosphere and glass melt corrosion at high temperature at the same time, so that the application of the breather pipe is greatly limited, particularly in the preparation of high-quality fluoride glass optical fiber. The breather pipe of the invention can resist CF at 1300 ℃ at the same time₄、SF₆、NF₃、HF、F₂The corrosion of the active gas and the zirconium fluoride, aluminum fluoride and indium fluoride glass melt can meet the requirement.

Description of the drawings:

FIG. 1 is a schematic view of a corrosion-resistant vent tube for fluoride glass reactive atmosphere treatment according to the present invention

Fig. 2 is a top view of fig. 1.

The specific implementation mode is as follows:

the present invention is further illustrated by the following examples, which should not be construed as limiting the scope of the invention.

Example 1:

mixing nano carbon powder and nano MgF₂The powder is mixed evenly under ball milling according to the proportion that the mole percentage is 47 percent. Obtaining graphite and MgF by dry pressing and cold isostatic pressing₂The nanometer multiphase ceramic cylindrical vent pipe biscuit. And then preparing the ventilation pipe biscuit into a semi-compact ventilation pipe under vacuum sintering. Introducing nitrogen trifluoride gas (NF)₃) Introducing into semi-compact ventilation tube for 7 min; the snorkel is then sealed at both ends and inserted into the fluoride glass melt for a 12min hold time. Sintering the breather pipe by hot isostatic pressing to obtain a glass carbon material with an outer pipe wall and magnesium fluoride (MgF) with an inner pipe wall₂) The ceramic material has graphite and MgF as the middle layer₂The compact corrosion-resistant breather pipe made of the nano complex phase ceramic material. The breather pipe can be repeatedly used by erosion of active gases such as CF4, SF6, NF3, HF, F2 and the like and a zirconium fluoride, aluminum fluoride and indium fluoride glass melt under the condition of melting glass with the highest temperature of 1300 ℃, has no damage on the surface, and meets the use requirement.

The parameters of example 2-example 28 are as follows:

Claims (4)

1. the corrosion-resistant breather pipe for fluoride glass reactive atmosphere treatment is characterized by sequentially consisting of an inner pipe wall (2), an intermediate layer (3) and an outer pipe wall (1) from inside to outside, wherein the outer pipe wall (1) is made of a glass carbon material, and the inner pipe wall (2) is made of magnesium fluoride (MgF)₂) The intermediate layer (3) is made of graphite and MgF₂The nanometer complex phase ceramic material.

2. The method of making a corrosion resistant vent pipe of claim 1, comprising the steps of:

step 1), mixing nano carbon powder A and nano MgF₂The powder B is uniformly mixed under ball milling according to the proportion to obtain powder, and the molar proportion of A (A + B) is 45-60 percent;

step 2), obtaining graphite and MgF from the powder through dry pressing and cold isostatic pressing₂The nano multiphase ceramic cylindrical vent pipe biscuit is made into a semi-compact vent pipe through vacuum sintering;

step 3), the semi-compact vent pipe is etched in two steps: the first step is to introduce nitrogen trifluoride gas (NF)₃) Introducing the gas into a semi-compact ventilation pipe for 1-60 min, and passing through NF₃Reacting the gas with carbon to obtain MgF₂A ceramic inner wall; secondly, sealing two ends of the vent pipe, inserting the vent pipe into the fluoride glass melt, maintaining for 1-240 min, and allowing MgF to pass through₂Reacting with a perfluorinated glass melt to obtain a glassy carbon outer wall;

and 4), sintering the vent pipe through hot isostatic pressing to obtain the corrosion-resistant vent pipe.

3. The method for preparing the corrosion-resistant vent pipe according to claim 2, wherein the venting time is 20-40 min.

4. The method of making a corrosion resistant vent pipe of claim 2 wherein said holding time is 20-100 min.

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