A ceramic tube sleeve sealing structure based on oxygen probe and its preparation method

Abstract

The invention discloses a ceramic tube sleeve sealing structure based on an oxygen probe and a preparation method thereof, comprising a high-aluminum tube and a zirconia tube inserted into the end of the high-aluminum tube, a sealing device is arranged between the zirconia tube and the high-aluminum tube, the sealing device comprises a high-temperature ceramic glue filled in the gap between the high-aluminum tube and the tube wall of the zirconia tube and a ceramic glaze coating located at the end of the high-aluminum tube and connected to the zirconia tube, the ceramic glaze coating is arranged in an annular shape and covers the end face of the high-temperature ceramic glue as a whole, during the production, a centering auxiliary rod is limitedly inserted into the high-aluminum tube, and then the zirconia tube is inserted into the high-aluminum tube, and the high-temperature ceramic glue is filled from the tube mouth of the connection between the high-aluminum tube and the zirconia tube to the gap between the zirconia tube and the high-aluminum tube until the colloid fills the annular gap between the two, and ceramic glaze is applied to the tube mouth of the high-aluminum tube to form a ceramic glaze coating. Based on the measurable distance of the existing oxygen probe, the invention can ensure the airtight requirement according to the working condition requirements and realize the measurement of the oxygen content at a long distance.

Description

Technical Field

[0001] The invention relates to the technical field of sensor equipment, and in particular to a ceramic tube sleeve sealing structure based on an oxygen probe and a preparation method thereof. Background Art

[0002] At present, oxygen sensors (oxygen probes) are widely used, mainly in protective atmosphere heat treatment, gas carburizing and energy saving of large boilers. Gas carburizing is one of the most widely used and important heat treatment methods in the machinery manufacturing industry. The quality of carburized parts depends to a large extent on the surface carbon concentration. However, for a long time, the carburizing process has been generally controlled by experience and regular inspection of test rods. The surface carbon concentration of carburized parts fluctuates greatly, and a large amount of carbides often appear in the surface metallographic structure, which seriously affects the product quality and reduces the service life of carburized parts. In recent years, the emergence of oxygen sensors (oxygen probes) has brought a technological revolution to gas carburizing heat treatment, making it possible to accurately control the carbon potential of furnace gas during carburizing, and is conducive to the realization of microcomputer automatic control, which has far-reaching significance for improving the quality of carburizing heat treatment and technical transformation of pit carburizing furnaces.

[0003] The oxygen sensor consists of two inner and outer platinum (Pt) electrodes and a stable zirconia ceramic in between. When the outer side of the probe is in contact with the gas to be measured and reference air is introduced into the inner side, an oxygen concentration difference cell is formed due to the different oxygen concentrations on both sides of the zirconia tube, generating an electric potential on the inner and outer electrodes, thereby measuring the oxygen content in the gas to be measured.

[0004] Based on this, the ceramic tube on the oxygen sensor plays a key role in the entire application process of the oxygen sensor. It is a key component in the oxygen measurement work. Then, the ceramic tube in the existing specifications of the oxygen sensor has an application length of 200mm to 1200mm, which cannot meet all needs. Once the area to be measured is located in a deeper position, the oxygen content cannot be effectively measured. In view of this, there is currently a lack of an effective sleeve structure for lengthening the ceramic tube to meet the requirements of industrial applications. Summary of the invention

[0005] 1. Technical issues to be resolved

[0006] In order to overcome the shortcomings of the existing technology, a ceramic tube sleeve sealing structure based on an oxygen probe and a preparation method thereof are proposed, which can solve the problem of limited length of the ceramic tube of the existing oxygen probe, can ensure the airtightness requirements according to the working conditions, and realize the long-distance oxygen content measurement.

[0007] (II) Technical solution

[0008] The present invention is achieved through the following technical scheme: The present invention proposes a ceramic tube sleeve sealing structure based on an oxygen probe, comprising a high-aluminum tube and a zirconia tube inserted into the end of the high-aluminum tube, a sealing device is arranged between the zirconia tube and the high-aluminum tube to achieve sealing of the connection gap between the two, the sealing device comprises a high-temperature ceramic glue filled in the gap between the high-aluminum tube and the wall of the zirconia tube, and a ceramic glaze coating located at the end of the high-aluminum tube and connected to the zirconia tube, the ceramic glaze coating is arranged in an annular shape and covers the end face of the high-temperature ceramic glue as a whole.

[0009] Furthermore, the high-aluminum tube is a through tube with through holes at both ends, and the zirconia tube is a tube body structure with a single-side opening, and the open side is connected to the high-aluminum tube by a socket connection.

[0010] A method for preparing a ceramic tube sleeve sealing structure based on an oxygen probe comprises the following steps:

[0011] 1) Concentricity: Place a centering auxiliary rod in the high-aluminum tube, and then insert the zirconia tube into the high-aluminum tube, so that the concentricity of the high-aluminum tube and the zirconia tube can reach within 0.1mm when they are connected;

[0012] 2) Filling with high-temperature ceramic glue: Fill the high-temperature ceramic glue from the nozzle where the high-aluminum tube and the zirconia tube are connected to the gap between the zirconia tube and the high-aluminum tube until the glue fills the annular gap between the two, and then remove the centering auxiliary rod. The filling is completed when the filling cannot be continued and the high-temperature ceramic glue overflows from the nozzle of the high-aluminum tube;

[0013] 3) Gel: The structure in step 2) is placed at room temperature for 24 hours;

[0014] 4) Step-by-step curing: put it into an oven at 80℃, 100℃, and 150℃ and bake it for 1 hour respectively; 5) High temperature curing: put it into a box-type electric furnace at 950℃ for heating and curing for 20 to 30 minutes;

[0015] 6) Cooling and curing: Cool down to 150-200℃ in the furnace and then air cool out of the furnace;

[0016] 7) Glaze sealing: Apply ceramic glaze to the mouth of the high-aluminum tube to form a ceramic glaze coating, which fully covers the end face of the high-temperature ceramic glue, and is connected to the edge of the high-aluminum tube on the outside and the zirconia tube on the inside;

[0017] 8) Standing: The structure in step 7) is stably placed at room temperature for 24 hours;

[0018] 9) Gradually solidify the glaze: sequentially place the structure in step 8) into an oven at 80°C, 100°C, and 150°C and bake for 1 hour respectively;

[0019] 10) High temperature glaze curing: put it into a box-type electric furnace at 1100-1200℃ for heating and curing for 20-30 minutes;

[0020] 11) Secondary cooling and solidification: Cool down to 150-200℃ in the furnace and then take out of the furnace for air cooling.

[0021] Furthermore, the centering auxiliary rod includes a rod body and a limiting column, the diameter of the rod body is consistent with the inner diameter of the zirconia tube and the zirconia tube can be freely sleeved on the rod body, the limiting column is fixed on the rod body and its outer diameter is consistent with the inner diameter of the high aluminum tube, and the limiting column can slide freely in the inner cavity of the high aluminum tube

[0022] (III) Beneficial effects

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The ceramic tube sleeve sealing structure based on the oxygen probe mentioned in the present invention and the preparation method thereof are no longer limited to the length limit of the oxygen probe of the existing oxygen sensor. According to different usage conditions, a probe tube of appropriate length can be prepared. The whole adopts a sleeve form, which not only realizes the oxygen measurement function through the zirconia tube, but also combines the characteristic of arbitrary selection of the length of the high-aluminum tube to produce a non-standard oxygen sensor. The connection between the high-aluminum tube and the zirconia tube adopts the form of high-temperature ceramic glue combined with ceramic glaze coating, which is not only convenient to manufacture but also has a good airtightness effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the structure of the present invention.

[0026] Figure 2 This is a schematic diagram of the installation of the centering auxiliary rod.

[0027] 1-high aluminum tube; 2-zirconia tube; 3-high temperature ceramic glue; 4-ceramic glaze coating; 5-centering auxiliary rod; 51-rod body; 52-limiting column. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0029] like Figure 1 and Figure 2A ceramic tube sleeve sealing structure based on an oxygen probe is shown, comprising a high aluminum tube 1 and a zirconia tube 2 inserted into the end of the high aluminum tube 1, a sealing device is arranged between the zirconia tube 2 and the high aluminum tube 1 to achieve sealing of the connection gap between the two, the sealing device comprises a high temperature ceramic glue 3 filled in the gap between the walls of the high aluminum tube 1 and the zirconia tube 2, and a ceramic glaze coating 4 located at the end of the high aluminum tube 1 and connected to the zirconia tube 2, the ceramic glaze coating 4 is arranged in an annular shape and covers the end face of the high temperature ceramic glue 3 as a whole.

[0030] The high aluminum tube 1 is a through tube with through holes at both ends, and the zirconia tube 2 is a tube structure with a single-side opening, and the open side is connected to the high aluminum tube 1 by a socket connection.

[0031] Example

[0032] A method for preparing a ceramic tube sleeve sealing structure based on an oxygen probe comprises the following steps:

[0033] 1) Concentricity: insert the centering auxiliary rod 5 into the high aluminum tube 1, and then insert the zirconia tube 2 into the high aluminum tube 1, so that the high aluminum tube 1 and the zirconia tube 2 are sleeved and connected, and the concentricity is within 0.1 mm;

[0034] 2) Filling with high-temperature ceramic glue: filling the high-temperature ceramic glue 23 from the tube opening where the high-aluminum tube 1 and the zirconia tube 2 are connected to the gap between the zirconia tube 2 and the high-aluminum tube 1 until the glue fills the annular gap between the two, and then taking out the centering auxiliary rod 5. The filling at this point is completed when the high-temperature ceramic glue 23 overflows from the tube opening of the high-aluminum tube 2 and cannot be filled further;

[0035] 3) Gel: The structure in step 2) is placed at room temperature for 24 hours;

[0036] 4) Step by step solidification: put it into the oven at 80℃, 100℃ and 150℃ and bake for 1 hour respectively;

[0037] 5) High temperature curing: put it into a box-type electric furnace at 950°C for heating and curing for 20 minutes; 6) Cooling curing: cool it to 150°C in the furnace and then take it out of the furnace for air cooling;

[0038] 7) Glaze sealing; Ceramic glaze is applied to the mouth of the high aluminum tube 1 to form a ceramic glaze coating 4, which fully covers the end surface of the high temperature ceramic glue 23, and is connected to the edge of the high aluminum tube 1 on the outside and connected to the zirconia tube 2 on the inside;

[0039] 8) Standing: The structure in step 7) is stably placed at room temperature for 24 hours;

[0040] 9) Gradually solidify the glaze: sequentially place the structure in step 8) into an oven at 80°C, 100°C, and 150°C and bake for 1 hour respectively;

[0041] 10) High temperature glaze curing: put it into a box-type electric furnace at 1185~℃ for heating and curing for 25 minutes;

[0042] 11) Secondary cooling and curing: Cool down to 150℃ in the furnace and then take out of the furnace for air cooling.

[0043] Among them, the centering auxiliary rod 5 includes a rod body 51 and a limiting column 52. The diameter of the rod body 51 is consistent with the inner diameter of the zirconia tube 2 and the zirconia tube 2 can be freely sleeved on the rod body 51. The limiting column 52 is fixed on the rod body 51 and its outer diameter is consistent with the inner diameter of the high aluminum tube 1. The limiting column 52 can slide freely in the inner cavity of the high aluminum tube 1.

[0044] It should be noted that the bottom of the rod body 51 is flush with the mouth of the high aluminum tube 1. At this time, the distance between the root of the rod body 51 and the end face of the limit column 52 is the insertion depth of the zirconia tube 2 (this depth is also the height of the high-temperature ceramic glue 3). A scale can be set on the rod body 51. If the insertion depth of the zirconia tube 2 needs to be adjusted, the bottom of the rod body 51 can be appropriately extended out of the mouth of the high aluminum tube 1 by a corresponding length.

[0045] The sleeve-type extended ceramic tube produced by the present invention has good air tightness and can be used in oxygen probes. The detection part of the oxygen probe (i.e., the zirconia tube 2) can be used to meet the demand for oxygen measurement at a longer distance. Since the length of the high-aluminum tube 1 can be arbitrarily selected, the defect of the fixed specifications of the existing oxygen probe can be avoided, and the oxygen measurement demand under complex working conditions can be met.

[0046] The above-described embodiments are merely descriptions of preferred implementations of the present invention, and are not intended to limit the concept and scope of the present invention. Without departing from the design concept of the present invention, various modifications and improvements made by ordinary persons in the art to the technical solution of the present invention should fall within the protection scope of the present invention, and the technical contents for which protection is sought in the present invention have been fully recorded in the claims.

Claims

1. A method for preparing a ceramic tube sleeve sealing structure based on an oxygen probe, characterized in that: The ceramic tube sleeve sealing structure based on the oxygen probe comprises a high aluminum tube (1) and a zirconia tube (2) inserted into the end of the high aluminum tube (1); a sealing device is arranged between the zirconia tube (2) and the high aluminum tube (1) to achieve sealing of the connection gap between the two; the sealing device comprises a high temperature ceramic glue (3) filled in the gap between the tube walls of the high aluminum tube (1) and the zirconia tube (2) and a ceramic glaze coating (4) located at the end of the high aluminum tube (1) and connected to the zirconia tube (2); the ceramic glaze coating (4) is arranged in an annular shape and entirely covers the end face of the high temperature ceramic glue (3); the high aluminum tube (1) is a through tube with through holes at both ends; the zirconia tube (2) is a tube body structure with a single-side opening and the open side is connected to the high aluminum tube (1) by a socket connection; the specific preparation comprises the following steps: 1) Concentricity: a centering auxiliary rod (5) is placed in the high-aluminum tube (1) to limit the position, and then the zirconia tube (2) is inserted into the high-aluminum tube (1), so that the high-aluminum tube (1) and the zirconia tube (2) are sleeved and connected to each other with a concentricity within 0.1 mm; 2) Filling with high-temperature ceramic glue: filling the high-temperature ceramic glue (3) from the tube opening at the connection between the high-aluminum tube (1) and the zirconia tube (2) to the gap between the zirconia tube (2) and the high-aluminum tube (1) until the glue fills the annular gap between the two, and then taking out the centering auxiliary rod (5). The filling is completed when the filling cannot be continued and the high-temperature ceramic glue (3) overflows from the tube opening of the high-aluminum tube (1); 3) Gel: The structure in step 2) is placed at room temperature for 24 hours; 4) Stepwise solidification: the product of step 3) is placed in an oven at 80°C, 100°C, and 150°C and baked for 1 hour respectively; 5) High temperature curing: Place the product in step 4) in a box-type electric furnace at 950°C for heating and curing for 20 to 30 minutes; 6) Cooling and curing: Cool down to 150-200℃ in the furnace and then air cool out of the furnace; 7) Glaze sealing: Ceramic glaze is applied to the mouth of the high-aluminum tube (1) to form a ceramic glaze coating (4), which fully covers the end surface of the high-temperature ceramic glue (3), and is connected to the edge of the high-aluminum tube (1) on the outside and to the zirconia tube (2) on the inside; 8) Standing: The structure in step 7) is stably placed at room temperature for 24 hours; 9) Gradually solidify the glaze: sequentially place the structure in step 8) into an oven at 80°C, 100°C, and 150°C and bake for 1 hour respectively; 10) High temperature glaze curing: the product of step 9) is placed in a box-type electric furnace at 1100-1200°C for heating and curing for 20-30 minutes; 11) Secondary cooling and solidification: Cool down to 150-200℃ in the furnace and then take out of the furnace for air cooling.

2. The method for preparing a ceramic tube sleeve sealing structure based on an oxygen probe according to claim 1, characterized in that: The centering auxiliary rod (5) comprises a rod body (51) and a limiting column (52); the diameter of the rod body (51) is consistent with the inner diameter of the zirconia tube (2), and the zirconia tube (2) can be freely sleeved on the rod body (51); the limiting column (52) is fixed on the rod body (51) and its outer diameter is consistent with the inner diameter of the high aluminum tube (1); the limiting column (52) can slide freely in the inner cavity of the high aluminum tube (1).

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