A steel-lined silicon carbide structure and a method for manufacturing its lining

Abstract

The present invention discloses a steel-lined silicon carbide structure, which includes a first steel part flange, a steel part cylinder, a silicon carbide lining layer, iron blocks, fiberglass cloth, and a second steel part flange. The present invention also provides a method for manufacturing the lining of the steel-lined silicon carbide structure, comprising the following steps: preparing a mold; welding iron blocks to the inner wall of the steel part cylinder; pasting fiberglass cloth on the inner wall surface of the steel part cylinder after applying high-temperature resistant glue and drying; loading the core into the steel part cylinder and completing the assembly; pouring silicon carbide material into the gap between the steel part cylinder and the core from the feed port in the upper core positioning mold, vibrating and compacting it with a vibrator and then leaving it to cure; demolding after the silicon carbide cures to form the silicon carbide lining layer; inspecting the silicon carbide lining layer, repairing defects, and leaving it for 24 hours after the repair is completed; putting it into an oven and setting a sintering program for sintering. The present invention uses foam as the core, realizing the manufacture of silicon carbide lining for special parts, such as square-round pipes, elbows, etc.

Description

[Technical field]

[0001] The invention relates to the technical field of a manufacturing process for a silicon carbide product, in particular to the technical field of a manufacturing process for a steel-lined silicon carbide product. [Background technology]

[0002] Silicon carbide is a high-strength integral composite inorganic material with high mechanical strength, wear resistance and thermal shock resistance. Its unique high-temperature resistance can be used in temperatures up to 1500°C. As a new type of high-temperature wear-resistant material, it is necessary to combine the excellent processing properties of steel with the heat and wear resistance of silicon carbide in many applications. However, during the manufacturing and use process, due to the difference in thermal conductivity between steel and silicon carbide, the thermal expansion and contraction of steel is faster than that of silicon carbide, and it is easy to have defects such as cracking caused by extrusion, which greatly shortens the service life of the product. [Summary of the invention]

[0003] The purpose of the present invention is to solve the problem of cracking of steel-lined silicon carbide during production and use due to different thermal conductivity of the two in the prior art, and propose a steel-lined silicon carbide structure and a lining production method thereof. In order to solve the problem of cracking of silicon carbide caused by extrusion due to thermal expansion and contraction between steel parts and silicon carbide lining layers, a buffer zone is set between the two, and at the same time, the sintering process of steel-lined silicon carbide is changed so that the temperature during sintering rises and falls slowly. During use, thermal insulation material is added to the outer wall of the steel part to slowly raise and lower its temperature, so that the silicon carbide of the lining is not squeezed by the steel part and maintains its integrity, thereby achieving the purpose of extending the service life.

[0004] To achieve the above-mentioned purpose, the present invention proposes a steel-lined silicon carbide structure, comprising a first steel flange, a steel cylinder, a silicon carbide lining layer, an iron block, a glass fiber cloth, and a second steel flange, wherein the first steel flange and the second steel flange are welded at both ends of the steel cylinder, and an iron block is welded on the inner wall of the steel cylinder; a silicon carbide lining layer is arranged inside the steel cylinder, and a glass fiber cloth is pasted on the inner wall of the steel cylinder between the steel cylinder and the silicon carbide lining layer; a lower positioning mold of a mold core is fixed to the bottom of the second steel flange by bolts, a blind hole is arranged in the middle of the lower positioning mold of the mold core, and a mold core is matched in the blind hole, silicon carbide is filled between the inner wall of the glass fiber cloth and the mold core to form a silicon carbide lining layer, and an upper positioning mold of a mold core is fixed to the upper end face of the first steel flange by bolts, a circular through hole is arranged in the middle of the upper positioning mold of the mold core, and the circular through hole passes through the mold core.

[0005] Preferably, the positioning mold on the mold core is provided with a feeding port and an exhaust port.

[0006] Preferably, the thickness of the glass fiber cloth is 2 mm.

[0007] The present invention also proposes a method for manufacturing a lining of a steel-lined silicon carbide structure, comprising the following steps:

[0008] Step 1: According to the inner diameter of the steel cylinder and the thickness of the silicon carbide lining layer to be manufactured, a mold core of corresponding specifications is manufactured, and at the same time, an upper mold core positioning mold and a lower mold core positioning mold matching the mold core are processed and manufactured;

[0009] Step 2: Weld a number of iron blocks on the inner wall of the steel cylinder, and the iron blocks are spaced 300mm to 400mm in the circumferential direction and 500mm in the longitudinal direction. The iron blocks are welded in two passes to prevent the silicon carbide of the lining from sliding off as a whole. After the iron blocks are welded, sandblasting and rust removal are performed;

[0010] Step 3: Apply high temperature resistant glue on the inner wall of the cleaned steel cylinder, stick the fiberglass cloth on the inner wall of the steel cylinder, and let it dry;

[0011] Step 4: Connect the lower mold core positioning mold to the second steel flange with bolts, install the mold core into the steel cylinder, and insert the lower end of the mold core into the blind hole in the middle of the lower mold core positioning mold, connect the upper mold core positioning mold to the first steel flange with bolts, and position the upper part of the mold core;

[0012] Step 5: Slowly pour the stirred silicon carbide material from the feed port in the upper mold core positioning mold into the gap between the steel cylinder and the mold core, compact it with a vibrator, and place it to solidify after compaction;

[0013] Step 6: After the silicon carbide is solidified to form the silicon carbide lining layer, remove the upper positioning mold, the lower positioning mold and the core; check the silicon carbide lining layer, repair the areas with pore defects, and leave it for 24 hours after the repair is completed;

[0014] Step 7: Place in the oven and set the sintering program for sintering.

[0015] Preferably, the sintering procedure is as follows: the temperature rises from 0 to 110°C (there is a certain amount of moisture in the silicon carbide layer) at a heating rate of 0.2°C / min, and the temperature is kept at 110°C for no less than 3 hours; the heating rate in the temperature range of 110 to 350°C is 0.3°C / min, and the temperature is kept at 350°C for no less than 5 hours; the heating rate from 350 to 1000°C is 0.25°C / min, and the temperature is kept at 1000°C for 6 hours; the cooling rate is 0.2°C / min to room temperature.

[0016] Preferably, the heating and cooling rates during the sintering process are controlled below 0.3°C / min, and insulation is performed at 110°C, 350°C and 1000°C. The insulation time depends on the thickness of the silicon carbide layer.

[0017] Beneficial effects of the present invention: The present invention adopts foam as a mold core to realize the production of silicon carbide linings for special parts, such as square and round pipes, elbows, etc.

[0018] The features and advantages of the present invention will be described in detail through embodiments in conjunction with the accompanying drawings.

Explanation of the Drawings

[0019] Figure 1 is the product structure diagram of a steel-lined silicon carbide structure and its lining manufacturing method of the present invention;

[0020] Figure 2 is the partial enlarged view of the product structure of a steel-lined silicon carbide structure and its lining manufacturing method of the present invention;

[0021] Figure 3 is the assembly pouring structure diagram of a steel-lined silicon carbide structure and its lining manufacturing method of the present invention.

[0022] In the figure: 1 - upper positioning die of the core mold, 2 - first steel part flange, 3 - steel part cylinder, 4 - silicon carbide lining layer, 5 - iron block, 6 - fiberglass cloth, 7 - core mold, 8 - second steel part flange, 9 - lower positioning die of the core mold.

Specific Embodiments

[0023] Refer to Figure 1 、 Figure 2 、 Figure 3 The present invention includes a first steel part flange 2, a steel part cylinder 3, a silicon carbide lining layer 4, an iron block 5, a fiberglass cloth 6 and a second steel part flange 8. The two ends of the steel part cylinder 3 are respectively welded with the first steel part flange 2 and the second steel part flange 8, and an iron block 5 is welded on the inner wall surface of the steel part cylinder 3; a silicon carbide lining layer 4 is arranged inside the steel part cylinder 3, and a fiberglass cloth 6 is pasted on the inner wall surface of the steel part cylinder 3 between the steel part cylinder 3 and the silicon carbide lining layer 4; a lower positioning die 9 of the core mold is fixed at the bottom of the second steel part flange 8 by bolts. A blind hole is provided in the middle of the lower positioning die 9 of the core mold, and a core mold 7 is fitted in the blind hole. Silicon carbide is filled between the inner wall surface of the fiberglass cloth 6 and the core mold 7 to form a silicon carbide lining layer 4. An upper positioning die 1 of the core mold is fixed on the upper end surface of the first steel part flange 2 by bolts. A circular through hole is provided in the middle of the upper positioning die 1 of the core mold, and the circular through hole passes through the core mold 7.

[0024] Specifically, the upper positioning die 1 of the core mold is provided with a feeding port and an exhaust port.

[0025] Specifically, the thickness of the fiberglass cloth 6 is 2 mm.

[0026] The present invention also proposes a method for manufacturing the lining of a steel-lined silicon carbide structure, including the following steps:

[0027] Step 1: Manufacture a core mold 7 with corresponding specifications according to the inner diameter of the steel part cylinder 3 and the thickness of the silicon carbide lining layer 4 to be manufactured. At the same time, process and manufacture an upper positioning die 1 of the core mold and a lower positioning die 9 of the core mold that are matched with the core mold 7;

[0028] Step 2: Weld a number of iron blocks 5 on the inner wall of the steel cylinder 3. The iron blocks 5 are spaced 300 mm to 400 mm in the circumferential direction and 500 mm longitudinally. There are 2 welds for the iron blocks 5 to prevent the overall sliding of the inner lining of silicon carbide. After the iron blocks 5 are welded, sandblasting and rust removal are carried out.

[0029] Step 3: Apply high-temperature resistant glue on the cleaned inner wall surface of the steel cylinder 3, paste the fiberglass cloth 6 on the inner wall of the steel cylinder 3, and let it dry.

[0030] Step 4: Connect the lower die core positioning die 9 to the second steel flange 8 with bolts, insert the die core 7 into the steel cylinder 3, and the lower end of the die core 7 is inserted into the blind hole in the middle of the lower die core positioning die 9. Connect the upper die core positioning die 1 to the first steel flange 2 with bolts to position the upper part of the die core 7.

[0031] Step 5: Slowly pour the stirred silicon carbide material into the gap between the steel cylinder 3 and the die core 7 from the feed port in the upper die core positioning die 1, and compact it with a vibrator. After compaction, let it stand for curing.

[0032] Step 6: After the silicon carbide cures to form the silicon carbide lining layer 4, remove the upper die core positioning die 1, the lower die core positioning die 9, and the die core 7; Check the silicon carbide lining layer 4, repair the places with porosity defects, and let it stand for 24 hours after repair.

[0033] Step 7: Place it in an oven and set the sintering program for sintering.

[0034] Specifically, the sintering program is as follows: The heating rate from 0 to 110 °C (there is a certain amount of moisture in the silicon carbide layer) is 0.2 °C / min, and it is kept warm at 110 °C for at least 3 h; The heating rate in the temperature range of 110 to 350 °C is 0.3 °C / min, and it is kept warm at 350 °C for not less than 5 h; The heating rate from 350 to 1000 °C is 0.25 °C / min, and it is kept warm at 1000 °C for 6 h; The cooling rate is 0.2 °C / min to room temperature.

[0035] Specifically, the heating and cooling rates during the sintering process are controlled below 0.3 °C / min, and at the same time, heat preservation is carried out at the temperature ranges of 110 °C, 350 °C, and 1000 °C. The heat preservation time depends on the thickness of the silicon carbide layer.

[0036] The working process of the present invention:

[0037] During the working process of a steel-lined silicon carbide structure and its lining manufacturing method of the present invention, it is described with reference to the accompanying drawings.

[0038] Example: DN800×200 (inner diameter of the cylinder φ800, thickness of the silicon carbide lining layer 20, inner diameter of the branch pipe φ201). The manufacturing process of the steel-lined silicon carbide includes the following operating steps:

[0039] A. Make a core 7 with corresponding specifications according to the inner diameter of the steel cylinder 3 and the thickness of the silicon carbide lining layer 4. The diameter of the core 7 is φ760, and the diameter of the branch pipe section is φ161. At the same time, process and manufacture the upper core positioning die 1 and the lower core positioning die 9 that match. The upper core positioning die 1 is provided with a feeding port and an exhaust port;

[0040] B. Weld iron blocks 5 with dimensions of 20×30×6 on the inner wall of the steel cylinder 3, with a circumferential interval of 310 and a longitudinal interval of 500, and stagger-weld 2 rows to prevent the overall sliding of the lined silicon carbide. After completion, perform sandblasting and rust removal;

[0041] C. Apply high-temperature resistant glue on the cleaned steel cylinder 3, paste a glass fiber cloth 6 with a thickness of 2 mm on the inner wall of the steel cylinder 3, and let it dry;

[0042] D. Connect the lower core positioning die 9 to the second steel flange 8 with bolts, insert the core 7 into the steel cylinder 3, insert the lower end into the inner hole of the lower core positioning die 9, and connect the upper core positioning die 1 to the first steel flange 2 with bolts to position the upper part of the core 7;

[0043] E. Slowly pour the stirred silicon carbide material into the gap between the steel cylinder 3 and the core 7 from the feeding port in the upper core positioning die 1, vibrate it with a vibrator, and place it for curing after completion;

[0044] F. After the silicon carbide is cured, remove the upper core positioning die 1, the lower core positioning die 9, and the core 7, check the silicon carbide lining layer 4, repair the defective parts, and put it into an oven for sintering; G. Set the sintering program: the temperature rising rate from 0 to 110 °C is 0.2 °C / min, keep it warm at 110 °C for 5 h, the temperature rising rate in the temperature range of 110 - 350 °C is 0.3 °C / min, keep it warm at 350 °C for 7 h, the temperature rising rate from 350 to 1000 °C is 0.25 °C / min, keep it warm at 1000 °C for 7 h, and the temperature decreasing rate is 0.2 °C / min to room temperature.

[0045] The above embodiments are illustrative of the present invention, not restrictive of the present invention. Any simply transformed scheme of the present invention belongs to the protection scope of the present invention.

Claims

1. A method for manufacturing a lining with a steel-lined silicon carbide structure, characterized in that, The following steps are involved: Step 1: According to the inner diameter of the steel cylinder (3) and the thickness of the silicon carbide lining layer (4) to be manufactured, a mold core (7) of corresponding specifications is manufactured, and at the same time, an upper mold core positioning mold (1) and a lower mold core positioning mold (9) matching the mold core (7) are processed and manufactured; Step 2: welding a plurality of iron blocks (5) on the inner wall of the steel cylinder (3), wherein the iron blocks (5) are spaced 300 mm to 400 mm in the circumferential direction and 500 mm in the longitudinal direction, and the iron blocks (5) are welded in two passes. After the welding of the iron blocks (5) is completed, sandblasting is performed to remove rust; Step 3: Apply high temperature resistant glue on the cleaned inner wall of the steel cylinder (3), stick the glass fiber cloth (6) on the inner wall of the steel cylinder (3), and let it dry; Step 4: Connect the mold core lower positioning mold (9) to the second steel flange (8) with bolts, install the mold core (7) into the steel cylinder (3), and insert the lower end of the mold core (7) into the blind hole in the middle of the mold core lower positioning mold (9), connect the mold core upper positioning mold (1) to the first steel flange (2) with bolts, and position the mold core (7) at the top; Step 5: slowly pour the stirred silicon carbide material from the feed port in the upper mold core positioning mold (1) into the gap between the steel cylinder (3) and the mold core (7), compact it with a vibrator, and place it to solidify after compaction; Step 6: After the silicon carbide is solidified to form the silicon carbide lining layer (4), the upper positioning mold (1), the lower positioning mold (9) and the core (7) are removed; the silicon carbide lining layer (4) is inspected, and the areas with pore defects are repaired, and the repaired areas are left for 24 hours; Step seven: Place in an oven and set a sintering program for sintering, the sintering program is as follows: the heating rate in the temperature section of 0 to 110°C is 0.2°C / min, and the temperature is kept at 110°C for not less than 3 hours; the heating rate in the temperature section of 110 to 350°C is 0.3°C / min, and the temperature is kept at 350°C for not less than 5 hours; the heating rate in the temperature section of 350 to 1000°C is 0.25°C / min, and the temperature is kept at 1000°C for 6 hours; the cooling rate is 0.2°C / min to room temperature; the heating and cooling rates during the sintering process are controlled below 0.3°C / min, and the temperature sections of 110°C, 350°C and 1000°C are kept warm, and the insulation time depends on the thickness of the silicon carbide layer.

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