Carbon / carbon furnace for brazing furnace and preparation method thereof

Abstract

The present invention relates to the technical field of brazing furnaces, and specifically to a carbon / carbon furnace for brazing furnaces and a preparation method thereof, which is made of a plurality of layers of carbon cloth and a plurality of layers of mesh tires alternately laid, and a preformed plate is made by a needle punching process, and then prepared by chemical vapor deposition, liquid phase impregnation, carbonization, and high-temperature graphitization in sequence. The carbon / carbon plate of the present invention not only greatly reduces the weight of the furnace, reduces the heat loss, but also has the additional advantage of long-term thermal stability. The carbon / carbon furnace has a small deformation amount during use, high flatness, and a long service life.

Description

Technical Field

[0001] The invention relates to the technical field of brazing furnaces, and in particular to a carbon / carbon furnace tool for a brazing furnace and a preparation method thereof. Background Art

[0002] Brazing furnaces usually require the use of many heavy tools in the brazing chamber. These tools include all heavy metal structures (such as grates, trays, racks, baskets, etc.) in the high temperature zone of the brazing furnace. All parts and tools placed in the high temperature zone need to be heated to the brazing temperature and then safely cooled to room temperature, and as little deformation as possible. If the tools in the furnace are very heavy, it will not only prolong the brazing process time, but also occupy a large part of the production capacity. Brazing companies have to pay a considerable amount of cost to heat these heavy tools to brazing temperature, often multiple times a day, day after day, year after year. The tools account for more than 90% of the total weight of the materials placed in the furnace, and less than 10% are parts that need to be brazed and provided to customers. The high cost makes these problems difficult to solve for the time being.

[0003] Based on this, the present invention designs a carbon / carbon furnace tool for a brazing furnace and a preparation method thereof to solve the above problems. Summary of the invention

[0004] In view of the above-mentioned shortcomings of the prior art, the present invention provides a carbon / carbon furnace for a brazing furnace and a preparation method thereof, which can effectively solve the problems of large heat loss, high cost, low comprehensive utilization rate of equipment, etc. during the brazing process.

[0005] Technical Solution

[0006] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0007] The present invention provides a carbon / carbon plate for brazing furnace, which is prepared by alternately laying a plurality of carbon cloth layers and a plurality of mesh layers, and forming a preformed plate by a needle punching process, and then sequentially preparing the plate by chemical vapor deposition, liquid phase impregnation, carbonization and high temperature graphitization.

[0008] Furthermore, after the high-temperature graphitization treatment, the preform plate is sequentially subjected to a halogen alkane treatment and a boron nitride coating treatment.

[0009] Furthermore, the impregnation liquid of the liquid phase impregnation is furfural resin.

[0010] Furthermore, the single-layer thickness of the carbon cloth is 0.2-0.8 mm; the single-layer thickness of the web tire is 0.2-0.8 mm; the number of layers of the carbon cloth and the web tire is 30-80 in total, and 1-5 layers of carbon cloth are stacked between two adjacent layers of the web tire.

[0011] A carbon / carbon furnace for a brazing furnace is made by assembling carbon / carbon plates with a mortise and tenon structure; preferably, the assembled furnace is a fence structure.

[0012] A method for preparing a carbon / carbon furnace tool for a brazing furnace includes the following process flow:

[0013] S1: preform processing; S2: cutting and blanking; S3: chemical vapor deposition; S4: liquid phase impregnation; S5: carbonization treatment; S6: high temperature graphitization; S7: halogen alkane treatment; S8: boron nitride coating treatment; S9: machining and assembly;

[0014] The density of the board after carbonization treatment in step S5 is ≥ 1.6 g / cm 3 When the temperature is 0.0400 W, the step S6 high temperature graphitization treatment is performed;

[0015] The density of the board after carbonization treatment in step S5 is less than 1.6 g / cm 3 When, return to step S4 liquid phase immersion treatment.

[0016] Furthermore, in the step S1, the laminated carbon cloth and the web are needle-punched by an automated flat needle-punching machine to form a preform sheet with a density of 0.45-0.5 g / cm³;

[0017] Among them, the carbon cloth is made of domestic T700 12K tow carbon fiber, and the mesh tire is made of imported T700 grade carbon fiber.

[0018] In the step S2, cutting is performed according to the finished product size of the furnace; preferably, cutting is performed into 1450 mm×50 mm×20 mm.

[0019] Furthermore, in step S3, the strips cut in step S2 are subjected to chemical vapor deposition treatment, the deposition temperature is 1000-1150° C., natural gas and catalytic gas are introduced, nitrogen is used as diluent gas, the furnace pressure is controlled to be 2000-4000 Pa, and the time is 300-400 hours;

[0020] Preferably, the catalytic gas is a hydrocarbon; most preferably, the catalytic gas is propane;

[0021] Preferably, by volume percentage, natural gas accounts for 60%, hydrocarbons 20%, and nitrogen 20%;

[0022] In the step S4, the blank after chemical vapor deposition is subjected to liquid phase densification treatment, and the densification material is selected from furfural resin, with a solid content of more than 70% and a residual carbon rate of more than 53-55%; the impregnation pressure is 1-3Mpa, the heating process temperature is controlled at 180-200°C, and the time is 5-12h.

[0023] Preferably, the immersion pressure is 2 MPa, the heating process temperature is controlled at 200° C., and the time is 8 hours.

[0024] Furthermore, in step S5, the impregnated sheet is placed between two graphite sheet fixtures, the carbonization temperature is 800-1200°C, and the time is 80-120h;

[0025] In the step S6, the carbon / carbon plate with the required density is subjected to high temperature graphitization treatment with tooling, the treatment temperature is 2000 ~ 2500 ℃, under vacuum, 25-35h;

[0026] In step S7, the halogenated alkane treatment method is as follows: carbon hexafluoride is introduced at a temperature of 2400-2800° C. for a time of 100-150 hours;

[0027] In the step S8, the boron nitride coating treatment method is as follows: the boron nitride coating is applied on the preform plate, and then heated under vacuum for 80-120 hours;

[0028] The raw materials of the boron nitride coating include boron nitride powder, anhydrous ethanol and phenolic resin, and the weight ratio of the boron nitride powder, anhydrous ethanol and phenolic resin is (3-7): (1-3): (1.5-4); preferably, the weight ratio of the boron nitride powder, anhydrous ethanol and phenolic resin is 5:2:3.

[0029] Furthermore, in step S9, the plate with qualified density is machined, and a mortise and tenon structure is used in the assembly process; preferably, a ceramic protective sleeve is added at the joint with the workpiece in the furnace.

[0030] Beneficial Effects

[0031] Compared with the known public technology, the technical solution provided by the present invention has the following beneficial effects:

[0032] (1) Carbon / carbon stoves not only greatly reduce the weight of the stove and reduce heat loss, but also have the additional advantage of long-term thermal stability. Carbon / carbon stoves have small deformation during use, high flatness and long service life.

[0033] (2) The present invention adopts carbon / carbon composite materials to replace the heat-resistant stainless steel in the traditional brazing furnace. The density of carbon-carbon is only one-fourth of that of metal parts, with small volume and strong bearing capacity. Carbon-carbon absorbs less heat and is more energy-efficient than traditional metal parts. About 50% of the heat can be used in the brazing process.

[0034] (3) Carbon-carbon materials are corrosion-resistant and not easily contaminated. This product does not require the application of solder resist. The product is designed as an assembled structure. If the local strength is damaged, it can be partially replaced. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the prior art descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 It is a structural schematic diagram of a carbon / carbon furnace for a brazing furnace according to the present invention;

[0037] Figure 2 This is a process flow chart of a carbon / carbon furnace tool for a brazing furnace according to the present invention;

[0038] Figure numbers: stove-10; plate-11. DETAILED DESCRIPTION

[0039] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] The present invention will be further described below in conjunction with the embodiments.

[0041] 1. Preparation of carbon / carbon stove

[0042] Embodiment 1:

[0043] like Figure 1 and Figure 2 As shown, a carbon / carbon furnace for a brazing furnace, the preparation method thereof is as follows:

[0044] S1: Preform processing: an automated flat needle punching machine is used to needle punch the alternately layered carbon cloth and mesh tire to prepare a preform sheet;

[0045] There are two layers of carbon cloth stacked between two adjacent layers of mesh tires; the carbon cloth is made of domestically produced T700 12K tow carbon fiber, with a surface density of 55 g / cm ² , thickness is 0.5mm; the mesh tire is made of imported T700 grade carbon fiber, which is opened into a mesh with a thickness of 0.5mm; it is made into a preform sheet with a density of 0.45g / cm³; the total number of layers of carbon cloth and mesh tire is 40;

[0046] S2: Cutting: Cut the materials according to the finished size of the furnace, and cut them into 1450mm×50mm×20mm;

[0047] S3: Chemical vapor deposition: The strips cut in step S2 are subjected to chemical vapor deposition treatment at a deposition temperature of 1100°C. By volume percentage, 60% natural gas and 20% propane are introduced, and 20% nitrogen is used as a diluent gas. The furnace pressure is controlled to be 3000 Pa, and the time is 350 hours.

[0048] S4: Liquid phase impregnation: The blank after chemical vapor deposition is subjected to liquid phase densification treatment, and the densification material is furfural resin (manufacturer is Shandong Shengquan, model FAR plus ), its solid content is 93%, residual carbon rate is 55%; impregnation pressure is 2Mpa, heating process temperature is controlled at 200℃, time is 8h;

[0049] S5: Carbonization treatment: put the impregnated sheet between two graphite sheet fixtures, the carbonization temperature is 950℃, and the time is 100h;

[0050] S6: High temperature graphitization: The carbon / carbon plate that meets the density requirements is treated with high temperature graphitization with tooling at a temperature of 2200°C under vacuum for 30 hours;

[0051] S7: Halogenated alkane treatment: introducing carbon hexafluoride at a temperature of 2600°C for 120 hours;

[0052] S8: Boron nitride coating treatment: applying a boron nitride coating on the preform plate, and then heating it under vacuum for 100 hours; wherein the raw materials of the boron nitride coating include boron nitride powder, anhydrous ethanol and phenolic resin, and the weight ratio of the boron nitride powder, anhydrous ethanol and phenolic resin is 5:2:3;

[0053] Among them, the phenolic resin (manufacturer Shengquan, model TC-02) adopts a phenolic resin with a solid content of 70%, ash content <500ppm, residual carbon rate of 40%, and pH 6;

[0054] S9: Machining and assembling: Machining the plates in step S8, and assembling them to meet the requirements of strength, rigidity and stability. Several prefabricated plates are assembled using mortise and tenon structures to obtain Figure 1 The carbon / carbon furnace shown, wherein the preform plates are arranged at equal intervals in the transverse and longitudinal directions;

[0055] In the above preparation process, the density of the board after carbonization treatment in step S5 is ≥1.6g / cm 3 When the carbonization treatment is carried out in step S6, the density of the plate after the carbonization treatment in step S5 is less than 1.6 g / cm 3 When, return to step S4 liquid phase immersion treatment.

[0056] Embodiment 2:

[0057] The only difference from Example 1 is that the surface density of the carbon cloth is 70 g / cm².

[0058] Embodiment 3:

[0059] The only difference from Example 1 is that in step S3, 60% natural gas and 0% propane are introduced by volume, and 20% nitrogen is used as the dilution gas.

[0060] Embodiment 4:

[0061] The only difference from Example 1 is that in step S3, 0% natural gas and 0% propane are introduced by volume, and 0% nitrogen is used as the dilution gas.

[0062] Embodiment 5:

[0063] The only difference from Example 1 is that phenolic resin is used in step S4, and the number of impregnations is the same as that in Example 1, which is 3 times. The phenolic resin is purchased from a manufacturer and model: Shengquan TC-02.

[0064] Embodiment 6:

[0065] The only difference from Example 1 is that epoxy resin is used in step S4, and the number of impregnations is the same as that in Example 1, which is 3 times. The epoxy resin is purchased from a manufacturer and model: Shengquan E-4-4.

[0066] Embodiment 7:

[0067] The only difference from Example 1 is that the number of immersions is one.

[0068] Embodiment 8:

[0069] The only difference from Example 1 is that there is no boron nitride coating treatment.

[0070] Embodiment 9:

[0071] The only difference from Example 1 is that there is no step S7: halogenated alkane treatment.

[0072] Table 1 - Density parameters and dipping times in Examples 1-9

[0073]

[0074] Note: Bulk density refers to the bulk density after multiple impregnation and carbonization.

[0075] By comparing Example 1 with Example 4, the addition of the chemical vapor deposition step can increase the bulk density of the preform; by comparing Example 1 with Example 3, in the chemical vapor deposition step, by adding catalytic gas propane, the bulk density of the preform can be increased; in addition, since the bulk density in this application is specified to be greater than or equal to 1.6 for high-temperature graphitization, the higher the initial bulk density, the fewer times of liquid phase impregnation will be, and the cost will be reduced. When performing liquid phase impregnation, the preform impregnated with furfural resin has a higher density and better effect.

[0076] (II) Performance parameters of carbon / carbon stoves

[0077] Heat loss: the time required to heat up to a specified temperature with the same power;

[0078] Surface roughness: needle drawing method;

[0079] Table 2 - Performance parameters of carbon / carbon stoves prepared in Examples 1-9

[0080]

[0081] Controlling the bulk density after carbonization treatment to above 1.6 can reduce the heat loss in the furnace and improve thermal stability. In addition, the surface roughness within this range is less than 3.2um, with high flatness, which is convenient for subsequent processing.

[0082] 3. Comparison with existing materials

[0083] Control group 1:

[0084] The only difference from Example 1 is that: in step S2, the cutting is performed according to the finished product size of the furnace, and the material is cut into 1450mm*1450*50mm;

[0085] Finally, a carbon-carbon solid structure with a specification of 1450mm*1450*50mm was prepared.

[0086] Control group 2:

[0087] The model used is sus304 stainless steel.

[0088] Effective work determination method: actual heating time / planned heating time;

[0089] Table 3 - Performance parameters of Example 1 and Control Groups 1-2

[0090]

[0091] It can be seen that the structure of the present application increases the furnace loading capacity, increases the effective work, and greatly reduces the waste of electric energy. The carbon-carbon stove of the present application reduces the weight of the stove, and the fence structure of the stove of the present application greatly reduces the overall weight.

[0092] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the protection scope of the technical solutions of the embodiments of the present invention.

Claims

1. A carbon / carbon plate for a brazing furnace, characterized in that: The preformed sheet is made of several layers of carbon cloth and several layers of mesh alternately, and then processed by a needle punching process, followed by chemical vapor deposition, liquid phase impregnation, carbonization, high temperature graphitization, halogen alkane treatment and boron nitride coating treatment; the density of the sheet after carbonization treatment is ≥1.6g / cm 3 When the high temperature graphitization treatment is carried out; The method for treating the halogenated alkane is as follows: introducing carbon hexafluoride at a temperature of 2400-2800°C for 100-150 hours; the method for treating the boron nitride coating is as follows: applying the boron nitride coating on the preform plate, and then heating it under vacuum for 80-120 hours; wherein the raw materials of the boron nitride coating include boron nitride powder, anhydrous ethanol and phenolic resin, and the weight ratio of the boron nitride powder, anhydrous ethanol and phenolic resin is 5:2:3; The chemical vapor deposition treatment, the deposition temperature is 1000 ~ 1150 ℃, into natural gas and catalytic gas, nitrogen as a diluent gas, control the furnace pressure of 2000 ~ 4000Pa, time 300-400h; the liquid impregnation impregnation liquid is furfural resin; The single-layer thickness of the carbon cloth is 0.2-0.8 mm; the single-layer thickness of the web tire is 0.2-0.8 mm; the number of layers of the carbon cloth and the web tire is 30-80 in total, and 1-5 layers of carbon cloth are stacked between two adjacent layers of the web tire.

2. A carbon / carbon furnace for a brazing furnace, characterized in that: The brazing furnace is manufactured by assembling the carbon / carbon plates for the brazing furnace according to any one of claims 1 using a mortise and tenon structure.

3. A method for preparing a carbon / carbon furnace tool for a brazing furnace as claimed in claim 2, characterized in that: It includes the following process flow: S1: preform processing; S2: cutting and blanking; S3: chemical vapor deposition; S4: liquid phase impregnation; S5: carbonization treatment; S6: high temperature graphitization; S7: halogen alkane treatment; S8: boron nitride coating treatment; S9: machining and assembly; The density of the board after carbonization treatment in step S5 is ≥ 1.6 g / cm 3 When the carbonization treatment is carried out in step S6, the density of the plate after the carbonization treatment in step S5 is less than 1.6 g / cm 3 When, return to step S4 liquid phase immersion treatment; The halogenated alkane treatment method in step S7 is as follows: introducing carbon hexafluoride at a temperature of 2400-2800° C. for a time of 100-150 hours; In step S8, the boron nitride coating treatment method is as follows: the boron nitride coating is applied on the preform plate, and then heated under vacuum for 80-120 hours; wherein the raw materials of the boron nitride coating include boron nitride powder, anhydrous ethanol and phenolic resin; and the weight ratio of the boron nitride powder, anhydrous ethanol and phenolic resin is 5:2:

3.

4. The method for preparing a carbon / carbon furnace tool for a brazing furnace according to claim 3, characterized in that: In the step S1, the carbon cloth and the web are needle-punched by an automated flat needle-punching machine to form a preform sheet with a density of 0.45-0.5 g / cm³; Among them, the carbon cloth is made of domestic T700 12K tow carbon fiber, and the mesh tire is made of imported T700 grade carbon fiber. In the step S2, cutting is performed according to the finished product size of the furnace; cutting is performed into 1450 mm×50 mm×20 mm.

5. The method for preparing a carbon / carbon furnace tool for a brazing furnace according to claim 3, characterized in that: In the step S3, the strips cut in step S2 are subjected to chemical vapor deposition treatment, the deposition temperature is 1000-1150° C., natural gas and catalytic gas are introduced, nitrogen is used as diluent gas, the furnace pressure is controlled to be 2000-4000 Pa, and the time is 300-400 hours; the catalytic gas is hydrocarbon; in terms of volume percentage, natural gas accounts for 60%, hydrocarbon 20%, and nitrogen 20%; In the step S4, the blank after chemical vapor deposition is subjected to liquid phase densification treatment, and the densification material is selected from furfural resin, with a solid content of more than 70% and a residual carbon rate of more than 53-55%; the impregnation pressure is 1-3Mpa, the heating process temperature is controlled at 180-200°C, and the time is 5-12h.

6. The method for preparing a carbon / carbon furnace tool for a brazing furnace according to claim 3, characterized in that: In the carbonization treatment of step S5, the impregnated sheet is placed between two graphite sheet fixtures, the carbonization temperature is 800-1200°C, and the time is 80-120h; In the step S6, the carbon / carbon plate that meets the density requirement is treated with a tool for high-temperature graphitization at a temperature of 2000-2500° C. under vacuum for 25-35 hours.

7. The method for preparing a carbon / carbon furnace tool for a brazing furnace according to claim 3, characterized in that: In step S9, the plates with qualified density are machined, and the mortise and tenon structure is used in the assembly process.

Images