Fixture and Its Preparation Method and Application

Abstract

The present invention relates to a fixture, a preparation method thereof and an application; the preparation method of the fixture comprises the following steps: providing a fixture body, and the material of the fixture body is selected from titanium-based stainless steel, aluminum-based stainless steel, titanium-aluminum-based stainless steel or iron-chromium-aluminum alloy; placing the fixture body in a device with an absolute vacuum degree of 10-1 Pa - 2×102 Pa and heating it to 1000 °C - 1150 °C, then introducing an oxygen-containing gas into the device for reaction, and cooling it after the reaction ends to obtain the fixture. In the fixture prepared by this preparation method, the protective layer is formed by oxidation after the elements of the fixture body diffuse to the surface, and is an integral structure with the fixture body, having a long service life, extremely low material cost and simple production process.

Description

Technical Field

[0001] The present invention relates to the technical field of fixtures, and in particular to fixtures and their preparation methods and applications. Background Art

[0002] During the brazing process of stainless steel and nickel-based alloys, fixtures are required to fix the assembled parts to be brazed to prevent deformation of the assembled parts during the welding process. Since the brazing filler metal used in the brazing process melts at high temperatures and infiltrates into the parts to be welded of the assembled parts through capillary action, there may sometimes be overflow, resulting in the adhesion of the assembled parts and the fixtures by the overflowed brazing filler metal and being unable to be separated.

[0003] To solve the problem of the adhesion of the brazing filler metal to the assembled parts and the fixtures, there are mainly two traditional methods: one is to use the coating method to cover the flux inhibitor on the surface of the fixture to prevent the assembled parts and the fixture from being adhered by the overflowed brazing filler metal. However, the commonly used high-temperature flux inhibitors titanium oxide and aluminum oxide have poor bonding strength with the fixture and will fall off into the interior of the assembled parts during use, resulting in poor cleanliness of the assembled parts. The assembled parts need to be cleaned, and the flux inhibitor needs to be reapplied before each brazing, with high usage costs and complex processes; the other is to spray a ceramic layer on the surface of the fixture using the spraying method. However, since the ceramic layer and the fixture have different thermal expansion coefficients and are only mechanically combined together, after the fixture is used more than 10 times, the ceramic layer will fall off, resulting in problems such as damage to the assembled parts and poor cleanliness. Summary of the Invention

[0004] Based on this, in view of the above problems, it is necessary to provide a fixture and its preparation method and application. In the fixture prepared by this preparation method, the protective layer is formed by the oxidation of the elements of the fixture body itself diffusing to the surface, which is an integral structure with the fixture body, has a long service life, extremely low material costs, and simple production processes.

[0005] The present invention provides a preparation method for a fixture, comprising the following steps:

[0006] Provide a fixture body, and the material of the fixture body is selected from titanium-based stainless steel, aluminum-based stainless steel, titanium-aluminum-based stainless steel or iron-chromium-aluminum material;

[0007] Place the fixture body in a device with an absolute vacuum of 10 -1 Pa - 2×10 2 Pa and heat it to 1000°C - 1150°C, then introduce an oxygen-containing gas into the device for reaction, and after the reaction is completed, cool it to obtain the fixture.

[0008] In one embodiment, in the step of introducing an oxygen-containing gas into the device for reaction, the reaction time is 0.5 h - 20 h.

[0009] In one embodiment, in the step of introducing an oxygen-containing gas into the device for reaction, the reaction is carried out in n stages, where n ≥ 2, and the reaction temperature in the nth stage is higher than that in the (n - 1)th stage.

[0010] In one embodiment, the reaction temperature in the nth stage is 1100°C - 1150°C.

[0011] In one embodiment, in the step of introducing an oxygen-containing gas into the device, the oxygen-containing gas is introduced continuously or intermittently.

[0012] In one embodiment, in the step of introducing an oxygen-containing gas into the device, the total amount of oxygen introduced per hour is 0.2 m 3 -10 m 3 。

[0013] In one embodiment, the oxygen-containing gas is selected from air or oxygen.

[0014] A fixture obtained by the method for preparing a fixture as described above, the fixture includes a fixture body and a protective layer coated on the surface of the fixture body, and the protective layer includes alumina and / or titanium oxide.

[0015] In one embodiment, the thickness of the protective layer is greater than or equal to 200 nm.

[0016] An application of a fixture as described above in brazing.

[0017] In the method for preparing the fixture provided by the present invention, during the vacuum heating of the fixture body, titanium atoms and / or aluminum atoms, iron atoms, chromium atoms, etc. in the fixture body undergo thermal motion at high temperature and diffuse to the surface of the fixture body, and then are oxidized by oxygen in the introduced oxygen-containing gas to form oxides. However, under the conditions of a reaction temperature of 1000°C - 1150°C and an absolute vacuum of 10 -1 Pa - 2×10 2 Pa, oxides of iron atoms, chromium atoms, etc. will be reduced by carbon in the fixture body, while oxides of aluminum atoms and / or titanium atoms will not be reduced by carbon in the fixture body, thereby forming a protective layer including alumina and / or titanium oxide on the surface of the fixture body.

[0018] Since the protective layer is formed by the diffusion of the elements of the fixture body to the surface and then oxidation, the protective layer and the fixture body are an integral structure. Compared with coating the fixture body with a solder mask, there is no need to coat the fixture body with a solder mask before each soldering, and there will be no problem that the protective layer falls off into the assembled parts during use, which affects the reliability of the assembled parts. Compared with spraying an oxide ceramic layer on the surface of the fixture body, there will be no problem that the protective layer falls off during use due to different thermal expansion coefficients, squeezing the assembled parts and causing damage to the assembled parts. In addition, since the aluminum and / or titanium forming the oxide in the protective layer are the elements of the fixture body itself, only the temperature and vacuum conditions need to be controlled to obtain the protective layer, which can reduce costs and simplify the production process. Brief Description of the Drawings

[0019] Figure 1 It is a schematic structural view of the fixture provided by the present invention.

[0020] In the figure: 10, fixture body; 20, protective layer. Detailed Embodiments

[0021] For the convenience of understanding the present invention, the present invention will be described more comprehensively below with reference to relevant embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0022] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0023] Combined Figure 1 As shown, the preparation method of the fixture provided by the present invention includes the following steps:

[0024] S10. Provide the fixture body 10, and the material of the fixture body 10 is selected from titanium-based stainless steel, aluminum-based stainless steel, titanium-aluminum-based stainless steel or iron-chromium-aluminum alloy;

[0025] S20. Place the fixture body 10 in a device with an absolute vacuum of 10 -1 Pa - 2×10 2 Pa and heat it to 1000°C - 1150°C, then introduce an oxygen-containing gas into the device for reaction, and cool it after the reaction to obtain the fixture.

[0026] It can be understood that the absolute vacuum degree refers to taking the "theoretical vacuum" as the zero position, indicating how much higher the pressure is than the "theoretical vacuum". The marked values are all positive values. The smaller this number is, the closer it is to the absolute vacuum, that is, the better the vacuum.

[0027] In step S10, when the material of the fixture body 10 is selected from titanium-based stainless steel, the protective layer 20 formed on the surface of the fixture body 10 contains titanium oxide. Optionally, the titanium-based stainless steel is selected from 304Ti, 316Ti, 436, 439, 430LX or 430LNT; when the material of the fixture body 10 is selected from aluminum-based stainless steel or iron-chromium-aluminum alloy, the protective layer 20 formed on the surface of the fixture body 10 contains aluminum oxide. Optionally, the aluminum-based stainless steel is selected from 501; when the material of the fixture body 10 is selected from titanium-aluminum-based stainless steel, the protective layer 20 formed on the surface of the fixture body 10 contains aluminum oxide and titanium oxide.

[0028] It can be understood that since the sizes and shapes of the brazing materials are not uniform, the size and shape of the fixture body 10 are not restricted. The shape and size of the fixture body 10 only need to match the assembled parts to be welded.

[0029] In order to avoid the oil stain on the surface of the fixture body 10 from affecting the contact area between the surface of the fixture body 10 and the oxygen-containing gas, so as to better form the coated protective layer 20 on the surface of the fixture body 10, before step S20, degreasing and removing oil stain treatment is carried out on the provided fixture body 10. Specifically, the degreasing and removing oil stain treatment can be carried out by means of alkali washing.

[0030] In step S20, during the heating process of the fixture body 10, titanium atoms and / or aluminum atoms, iron atoms, chromium atoms, etc. in the fixture body 10 undergo thermal motion at high temperature and diffuse to the surface of the fixture body 10, and then are oxidized by oxygen in the introduced oxygen-containing gas to form oxides. However, under the conditions of a reaction temperature of 1000°C - 1150°C and an absolute vacuum degree of 10 -1 Pa - 2×10 2 Pa, the oxides of iron atoms and chromium atoms, etc. will be reduced by carbon in the fixture body 10, while the oxides of aluminum atoms and / or titanium atoms will not be reduced by carbon in the fixture body 10, thereby forming a protective layer 20 including aluminum oxide and / or titanium oxide on the surface of the fixture body 10.

[0031] Since the protective layer 20 is formed by the diffusion of the elements of the fixture body 10 to the surface and then oxidation, the protective layer 20 and the fixture body 10 are an integral structure. Compared with coating a soldermask or spraying a ceramic layer on the surface of the fixture body 10, the service life is longer. In addition, since the aluminum and / or titanium forming the oxides in the protective layer 20 are the elements of the fixture body itself, only by controlling the temperature and vacuum conditions can the protective layer be obtained, thereby being able to reduce costs and simplify the production process.

[0032] Optionally, the introduced oxygen-containing gas includes, but is not limited to, air, oxygen, a mixed gas of oxygen and nitrogen, a mixed gas of oxygen and an inert gas, etc. Preferably, the introduced oxygen-containing gas is air or oxygen.

[0033] The reaction of introducing the oxygen-containing gas into the device can be carried out in one step or in multiple steps. In one embodiment, in the step of introducing the oxygen-containing gas into the device for reaction, the reaction is carried out in n stages, n≥2, and the reaction temperature in the nth stage is higher than that in the (n - 1)th stage, and the reaction temperature in the nth stage is 1100°C - 1150°C. Thus, with the successive increase of the reaction temperature, the diffusion rate of aluminum atoms and / or titanium atoms in the fixture body 10 to the surface also successively increases, so that the previously formed protective layer 20 will not hinder the formation of oxides of aluminum atoms and / or titanium atoms on the surface of the fixture body 10 later. With the increase of the reaction temperature, the compactness and thickness of the protective layer 20 also increase.

[0034] Optionally, the reaction can be carried out in two stages. For example, the reaction temperature in the first stage is 1000°C - 1100°C, and the reaction temperature in the second stage is 1100°C - 1150°C; or, the reaction temperatures in the first stage and the second stage are both 1100°C - 1150°C, but there is a temperature difference between them, and the temperature difference can be 10°C - 30°C.

[0035] Optionally, the reaction can be carried out in three stages. At this time, the reaction temperature in the third stage is higher than that in the second stage which is higher than that in the first stage. For example, the reaction temperature in the first stage is 1000°C - 1050°C, the reaction temperature in the second stage is 1050°C - 1100°C, and the reaction temperature in the third stage is 1100°C - 1150°C; or, the reaction temperature in the first stage is 1000°C - 1100°C, and the reaction temperatures in the second stage and the third stage are both 1100°C - 1150°C; or, the reaction temperatures in the first stage, the second stage and the third stage are all 1100°C - 1150°C.

[0036] Since the newly formed protective layer 20 is not compact, oxygen can permeate through it to continue reacting with aluminum and / or titanium on the surface of the fixture body 10 to form oxides. It can be understood that the longer the reaction time, the greater the mass fraction of aluminum elements and / or titanium elements on the surface of the fixture body 10. However, when the protective layer 20 on the surface of the fixture body 10 reaches a certain thickness and tightly coats the entire surface of the fixture body 10, further reaction does not better improve the thickness and compactness of the oxide layer 20. Therefore, in one embodiment, the reaction time is 0.5h - 20h, preferably 18h - 20h.

[0037] In one embodiment, in the step of introducing an oxygen-containing gas into the device, the oxygen-containing gas is introduced continuously or intermittently, and the total amount of oxygen introduced per hour is 0.2 m 3 -10 m 3 .

[0038] Among them, when the oxygen-containing gas is introduced continuously, the flow rate of oxygen in the introduced oxygen-containing gas is 0.2 m 3 / h - 10 m 3 / h, preferably 0.2 m 3 / h - 0.4 m 3 / h. When introduced continuously, the flow rate can remain unchanged or change; when the oxygen-containing gas is introduced intermittently, it is only necessary to ensure that the total amount of oxygen in the oxygen-containing gas introduced per hour is 0.2 m 3 / h - 10 m 3 / h, preferably 4 m 3 -6 m 3 . It can be understood that when the oxygen-containing gas is introduced continuously, the aluminum and / or titanium on the surface of the fixture body 10 can be more fully contacted with the air, and a protective layer 20 with a more uniform thickness can be formed on the surface of the fixture body 10. Therefore, it is preferred to introduce the oxygen-containing gas continuously.

[0039] Continue to refer to Figure 1 , the present invention also provides a fixture obtained by the above-mentioned fixture preparation method. The fixture includes a fixture body 10 and a protective layer 20 coated on the surface of the fixture body. The protective layer 20 includes aluminum oxide and / or titanium oxide.

[0040] In order to further extend the service life of the fixture, in one embodiment, the thickness of the protective layer 20 is greater than or equal to 200 nm, preferably 300 nm - 400 nm.

[0041] The present invention also provides an application of the fixture as described above in brazing. The fixture is used to fix the assembly during the brazing process.

[0042] Hereinafter, the fixture, its preparation method and application will be further described through the following specific examples.

[0043] Example 1

[0044] The 304Ti stainless steel is sheared and stamped into a fixture body, and then the surface of the fixture body is degreased and defatted by alkali washing.

[0045] The fixture body after degreasing and defatting treatment is placed in a vacuum brazing furnace with an absolute vacuum of 10 Pa for heating, and the fixture body is heated to 1100 °C. At this time, air is continuously introduced into the vacuum brazing furnace for reaction, and the flow rate of oxygen in the introduced air is 1 m 3 / h, and keep the reaction at 1100 °C for 10 h. After the reaction, cool it to obtain the fixture.

[0046] Example 2

[0047] Shear and stamp the FeCrAl alloy into a fixture body matching the assembly to be welded, and then degrease and remove oil and grease from the surface of the fixture body by alkaline washing.

[0048] Place the degreased and oil-removed fixture body in a vacuum brazing furnace with an absolute vacuum of 10 Pa for heating, and heat the fixture body to 1130 °C. At this time, continuously introduce oxygen into the vacuum brazing furnace for reaction, and the flow rate of oxygen is 0.2 m 3 / h, and keep the reaction at 1130 °C for 15 h. After the reaction, cool it to obtain the fixture.

[0049] Example 3

[0050] Shear and stamp the 304Ti stainless steel into a fixture body matching the assembly to be welded, and then degrease and remove oil and grease from the surface of the fixture body by alkaline washing.

[0051] Place the degreased and oil-removed fixture body in a vacuum brazing furnace with an absolute vacuum of 200 Pa for heating, and heat the fixture body to 1130 °C. At this time, continuously introduce a mixed gas of oxygen and nitrogen into the vacuum brazing furnace for reaction, and the flow rate of oxygen in the introduced mixed gas is 10 m 3 / h, and keep the reaction at 1130 °C for 20 h. After the reaction, cool it to obtain the fixture.

[0052] Example 4

[0053] Shear and stamp the 304Ti stainless steel into a fixture body matching the assembly to be welded, and then degrease and remove oil and grease from the surface of the fixture body by alkaline washing.

[0054] Place the degreased fixture body in a vacuum brazing furnace with an absolute vacuum of 3×10 -1 Pa for heating, and heat the fixture body to 1030 °C. At this time, continuously introduce air into the vacuum brazing furnace for reaction, and the flow rate of oxygen in the introduced air is 0.5 m 3 / h, and keep the reaction at 1030 °C for 5 h. After the reaction, cool it to obtain the fixture.

[0055] Example 5

[0056] The 304Ti stainless steel is sheared and stamped into a fixture body that matches the assembled parts to be welded. Then, the surface of the fixture body is degreased and defatted by alkali washing.

[0057] The fixture body after degreasing and defatting is placed in a vacuum brazing furnace with an absolute vacuum of 150 Pa for heating, and the fixture body is heated to 1140 °C. At this time, air is continuously introduced into the vacuum brazing furnace for reaction, and the flow rate of oxygen in the introduced air is 3 m 3 / h, and the reaction is maintained at 1140 °C for 15 h. After the reaction is completed, it is cooled to obtain the fixture.

[0058] Comparative Example 1

[0059] Comparative Example 1 is carried out with reference to Example 1, except that the stainless steel does not contain aluminum and titanium.

[0060] Comparative Example 2

[0061] Comparative Example 2 is carried out with reference to Example 1, except that the absolute vacuum is greater than 2×10 2 Pa.

[0062] Comparative Example 3

[0063] Comparative Example 3 is carried out with reference to Example 1, except that the heating and reaction are carried out in an air furnace.

[0064] Comparative Example 4

[0065] Comparative Example 4 is carried out with reference to Example 1, except that the heating temperature of the fixture body is less than 1000 °C.

[0066] Comparative Example 5

[0067] Comparative Example 5 is carried out with reference to Example 1, except that the heating temperature of the fixture body is greater than 1150 °C.

[0068] The thickness of the fixture protective layer, service life, and mass fractions of aluminum and titanium on the surface of the fixtures prepared in Examples 1-5 and Comparative Examples 1-5 are as follows. The specific test methods are shown below, and the test results are shown in Table 1.

[0069] Protective layer thickness: The distribution of O elements in the thickness direction of the material is measured using Auger electron spectroscopy to determine the thickness of the protective layer.

[0070] Service life: The fixture is repeatedly placed in the brazing furnace. When the fixture cracks, the number of times the fixture has passed through the furnace is determined.

[0071] Mass fraction of aluminum: The percentage of aluminum elements on the surface is measured using an energy spectrometer.

[0072] Mass fraction of titanium: The percentage of titanium element on the surface is tested using an energy spectrometer.

[0073] Table 1

[0074]

[0075] As can be seen from Table 1, the service life of the fixture of the present invention can reach more than 530 times, which is significantly better than coating a solder resist or spraying a ceramic layer on the surface of the fixture body. In addition, from the examples and comparative examples, it can be seen that the selection of the reaction temperature and vacuum degree in the present invention can reduce iron oxide and chromium oxide in the fixture body by carbon, thereby improving the solder resistance effect of the welding fixture.

[0076] Example 6

[0077] The 304Ti stainless steel is sheared and stamped into a fixture body matching the assembly to be welded, and then the surface of the fixture body is degreased and defatted by alkali washing.

[0078] The fixture body after degreasing and defatting is placed in a vacuum brazing furnace with an absolute vacuum of 2×10 -1 Pa for heating, and the fixture body is heated to 1100 °C. At this time, oxygen is introduced into the vacuum brazing furnace twice for reaction. Each time after introducing oxygen, the reaction lasts for 5 h, and the volume of oxygen introduced each time is 0.5 m 3 , and the reaction is carried out at 1130 °C. After the reaction is completed, it is cooled to obtain the fixture.

[0079] Example 7

[0080] The 304Ti stainless steel is sheared and stamped into a fixture body matching the assembly to be welded, and then the surface of the fixture body is degreased and defatted by alkali washing.

[0081] The fixture body after degreasing and defatting is placed in a vacuum brazing furnace with an absolute vacuum of 50 Pa for heating, and the fixture body is heated to 1120 °C. At this time, oxygen is introduced into the vacuum brazing furnace three times for reaction. Each time after introducing oxygen, the reaction lasts for 6 h. The volume of oxygen introduced for the first time is 2 m 3 , the volume of oxygen introduced for the second time is 3 m 3 , and the volume of oxygen introduced for the third time is 4 m 3 , and the reaction is carried out at 1120 °C. After the reaction is completed, it is cooled to obtain the fixture.

[0082] Example 8

[0083] The 304Ti stainless steel is sheared and stamped into a fixture body matching the assembly to be welded, and then the surface of the fixture body is degreased and defatted by alkali washing.

[0084] Place the fixture body after degreasing and defatting treatment in a vacuum brazing furnace with an absolute vacuum of 20 Pa for heating, and heat the fixture body to 1050 °C. At this time, air is introduced into the vacuum brazing furnace three times for reaction. The volume of oxygen in the air introduced for the first time is 2.5 m 3 , after reacting for 2 h, air is introduced for the second time. The volume of oxygen in the air introduced for the second time is 2.5 m 3 , after reacting for 3 h, air is introduced for the third time. The volume of oxygen in the air introduced for the third time is 2.5 m 3 , react for 5 h, and keep the reaction temperature at 1050 °C. After the reaction is completed, cool to obtain the fixture.

[0085] Measure the fixture protective layer thickness, service life, and the mass fractions of aluminum and titanium on the fixture surface prepared in Examples 6 - 8. The specific test methods are as shown above, and the test results are shown in Table 2.

[0086] Table 2

[0087]

[0088] Comparing Comparative Examples 1 - 5 and Examples 6 - 8, it can be seen that continuously introducing oxygen-containing gas is beneficial to improving the service life of the fixture.

[0089] Example 9

[0090] Shear and stamp 304Ti stainless steel into the fixture body, and then degrease and defat the surface of the fixture body by alkali washing.

[0091] Place the fixture body after degreasing and defatting treatment in a vacuum brazing furnace with an absolute vacuum of 5 Pa for heating, and heat the fixture body to 1130 °C. At this time, continuously introduce oxygen into the vacuum brazing furnace for reaction. The flow rate of the introduced oxygen is 0.5 m 3 / h. After reacting for 10 h, without changing the oxygen flow rate, raise the heating temperature to 1150 °C and react for 5 h. After the reaction is completed, cool to obtain the fixture.

[0092] Example 10

[0093] Shear and stamp 304Ti stainless steel into the fixture body, and then degrease and defat the surface of the fixture body by alkali washing.

[0094] Place the fixture body after degreasing and defatting treatment in a vacuum brazing furnace with an absolute vacuum of 5 Pa for heating, and heat the fixture body to 1050 °C. At this time, continuously introduce oxygen into the vacuum brazing furnace for reaction. The flow rate of the introduced oxygen is 1 m 3After reacting at / h for 5 h, without changing the oxygen flow rate, the heating temperature was increased to 1130 °C and the reaction continued for 5 h. After the reaction ended, it was cooled to obtain the fixture.

[0095] Example 11

[0096] The 304Ti stainless steel was sheared and stamped into a fixture body, and then the surface of the fixture body was degreased and defatted by alkali washing.

[0097] The fixture body after degreasing and defatting was placed in a vacuum brazing furnace with an absolute vacuum of 50 Pa for heating, and the fixture body was heated to 1100 °C. At this time, oxygen was continuously introduced into the vacuum brazing furnace for reaction, and the flow rate of the introduced oxygen was 4 m 3 / h. After reacting for 3 h, without changing the oxygen flow rate, the heating temperature was increased to 1140 °C and the reaction continued for 5 h. After the reaction ended, it was cooled to obtain the fixture.

[0098] Example 12

[0099] The 304Ti stainless steel was sheared and stamped into a fixture body, and then the surface of the fixture body was degreased and defatted by alkali washing.

[0100] The fixture body after degreasing and defatting was placed in a vacuum brazing furnace with an absolute vacuum of 5 Pa for heating, and the fixture body was heated to 1030 °C. At this time, oxygen was continuously introduced into the vacuum brazing furnace for reaction, and the flow rate of the introduced oxygen was 2 m 3 / h. After reacting for 3 h, without changing the oxygen flow rate, the heating temperature was increased to 1070 °C and the reaction continued for 4 h. Then, without changing the oxygen flow rate, the heating temperature was increased to 1130 °C and the reaction continued for 5 h. After the reaction ended, it was cooled to obtain the fixture.

[0101] The thickness of the fixture protective layer, service life, and the mass fractions of aluminum and titanium on the fixture surface prepared in Examples 9 - 12 were tested. The specific test methods were as shown before, and the test results are shown in Table 3.

[0102] Table 3

[0103]

[0104]

[0105] Comparing Comparative Examples 1 - 5 with Examples 9 - 12, it can be seen that carrying out the reaction in stages is also beneficial to improving the service life of the fixture.

[0106] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0107] The above-described embodiments merely represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. A method for preparing a fixture, characterized in that, it comprises the following steps: Provide a fixture body, and the material of the fixture body is selected from titanium-based stainless steel, aluminum-based stainless steel, titanium-aluminum-based stainless steel or iron-chromium-aluminum alloy; Place the fixture body in a device with an absolute vacuum of 10 -1 Pa - 2×10 2 Pa and heat it to 1000°C - 1150°C. Then, introduce an oxygen-containing gas into the device for reaction. The reaction is carried out in n stages, where n ≥ 2, and the reaction temperature in the nth stage is higher than that in the (n - 1)th stage. The reaction time is 18h - 20h. After the reaction is completed, cool it to obtain the fixture.

2. The method for preparing a fixture according to claim 1, characterized in that, the reaction temperature in the nth stage is 1100°C - 1150°C.

3. The method for preparing a fixture according to claim 1, characterized in that, in the step of introducing an oxygen-containing gas into the device, the oxygen-containing gas is introduced continuously or intermittently.

4. The method for preparing a fixture according to claim 3, characterized in that, In the step of introducing an oxygen-containing gas into the device, the total amount of oxygen introduced per hour is 0.2 m 3 -10 m 3 .

5. The method for preparing a fixture according to claim 4, characterized in that, the oxygen-containing gas is selected from air or oxygen.

6. A fixture, characterized in that, the fixture is obtained by the method for preparing a fixture according to any one of claims 1-5, and the fixture comprises a fixture body and a protective layer coated on the surface of the fixture body, and the protective layer includes alumina and / or titanium oxide.

7. The fixture according to claim 6, characterized in that, the thickness of the protective layer is greater than or equal to 200 nm.

8. Application of a fixture according to claim 6 or 7 in brazing.

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