CN106591758A - Arc spraying solid wire and method for preparing high-temperature oxidation resistant coating layer therefor - Google Patents

Abstract

The invention discloses an arc spraying solid wire and a method for preparing a high-temperature oxidation resistant coating layer therefor. The arc spraying solid wire is a FeCrAl base alloy, and consists of the raw materials in percentage by weight: 19-26 wt% of Cr, 5-9 wt% of Al, 0.05-0.08 wt% of Si, 0.05-0.08 wt% of C, 0.1-0.5 wt% of rare earth oxide Y2O3 and CeO2 mixture, and the balance of Fe. The method for preparing the high-temperature oxidation resistant coating layer for the solid wire for comprises the process of: burdening, smelting, filtration, casting, rolling, drawing, annealing, finishing, surface treatment, finished wire obtaining, high-temperature oxidation resistant coating layer forming. The method has the following advantages: the alloy wires with different components can be prepared through changing the ratios of all alloy components; the high-temperature oxidation resistance of the coating layer can be prominently improved through properly increasing the ratio of rare earth elements; the alloy wire has continuity and uniformity; and the prepared coating layer is better in high-temperature oxidation resistance.

Description

A kind of electric arc spraying solid wire material and its preparation method for high temperature oxidation resistant coating

technical field

The invention relates to the technical fields of thermal spraying technology and high-temperature protective coating, in particular to an electric arc spraying solid wire material and a method for preparing a high-temperature oxidation-resistant coating.

Background technique

Arc spraying is to use two wires to short-circuit at the mouth of the spray gun to generate an arc and melt the wires. The high-pressure air delivered by the air compressor atomizes the melted wires and sprays them onto the surface of the substrate to deposit them into a kind of high bonding strength and porosity. Thermal spraying method for low rate, low surface roughness coatings. Arc spraying wire includes two types, one is solid wire and the other is powder core wire. Solid wire is made by smelting, drawing and other processes, and is the main spraying material currently used. Solid wire mainly includes: non-ferrous metal wire, such as lead, zinc, copper, nickel and other metals and their alloys; ferrous metal wire, such as carbon steel, stainless steel, etc. Among them, iron-based alloy wire is widely used because of its good economic performance and excellent high-temperature oxidation resistance. FeCrAl alloy is an important electrothermal alloy. The alloy has excellent high temperature oxidation resistance (up to 1400°C) and high electrical resistivity. Due to the presence of a large amount of Cr and Al elements in the composition, the surface of the alloy will form dense Oxide film, thus prolonging the service life of the material. FeCrAl coating is prepared by arc spraying, in which Cr and Al generate Cr ₂ O ₃ and Al ₂ O ₃ at high temperature, and Cr ₂ O ₃ can improve the creep performance of Al ₂ O ₃ and refine the grains of Al ₂ O ₃ , reduce the cracking of the Al ₂ O ₃ film caused by the growth stress, inhibit the peeling of the oxide layer, promote the selective oxidation of Al, and make the Al ₂ O ₃ layer thicker and more dense and stable, thus preventing oxygen elements from entering the interior of the coating . The increase of the Al content in the wire can increase the resistivity, can more effectively convert electric energy into heat energy, and improve the thermal efficiency of arc spraying. In terms of economic performance, the price of FeCrAl alloy materials is 30%-50% cheaper than that of Ni-based alloys and stainless steel materials. Therefore, the preparation of high-temperature protective coatings with FeCrAl alloys has broad market prospects.

Contents of the invention

The object of the present invention is to provide a kind of electric arc spraying solid wire material and the method for preparing high-temperature oxidation-resistant coating thereof, the FeCrAl base high-temperature oxidation-resistant coating that makes has good high-temperature oxidation resistance and acid-base corrosion performance, and has no effect on base materials. to a good protective effect.

The technical solution of the present invention is: a solid wire material for arc spraying, the solid wire material is a FeCrAl-based alloy, which is composed of the following raw materials by weight percentage: Cr19-26wt%, Al5-9 wt%, Si0.05-0.08wt% , C0.05～0.08wt%, rare earth oxide Y ₂ O ₃ and CeO ₂ mixture 0.1～0.5wt%, Fe balance; in the rare earth oxide Y ₂ O ₃ and CeO ₂ mixture, Y ₂ O ₃ and The ratio of CeO2 is ₁ :1.

Preferably, the solid wire is a FeCrAl-based alloy composed of the following raw materials by weight percentage: Cr19-21wt%, Al5-7wt%, Si0.05-0.08wt%, C0.05-0.08wt%, rare earth oxide Y ₂ O ₃ and CeO ₂ mixture 0.1 ~ 0.2wt%, Fe balance;

Preferably, the solid wire is a FeCrAl-based alloy composed of the following raw materials by weight percentage: Cr23~26wt%, Al5~7wt%, Si0.05~0.08wt%, C0.05~0.08wt%, rare earth oxide Y ₂ O ₃ and CeO ₂ mixture 0.1 ~ 0.2wt%, Fe balance;

Preferably, the solid wire is a FeCrAl-based alloy composed of the following raw materials by weight percentage: Cr23-26wt%, Al7-9wt%, Si0.05-0.08wt%, C0.05-0.08wt%, rare earth oxide Y ₂ O ₃ and CeO ₂ mixture 0.1 ~ 0.2wt%, Fe balance;

Preferably, the solid wire is a FeCrAl-based alloy composed of the following raw materials by weight percentage: Cr23-26wt%, Al7-9wt%, Si0.05-0.08wt%, C0.05-0.08wt%, rare earth oxide Y ₂ O ₃ and CeO ₂ mixture 0.3 ~ 0.5wt%, Fe balance;

A method for preparing a high-temperature oxidation-resistant coating by electric arc spraying a solid wire, comprising the following steps:

(1) Ingredients: Fe powder, Cr powder, Al powder, Si powder, C powder, and Y ₂ O ₃ and CeO ₂ powder mixed in a ratio of 1:1 are mixed according to the above ratio, and mixed evenly;

(2) Melting: Put the prepared alloy raw materials into a vacuum induction furnace for melting, preheat to 400-550°C for 2-4 hours, and control the temperature of the alloy liquid at 1000-1200°C during melting, every 10-20min carry out electromagnetic stirring;

(3) Filtration: Filter the smelted alloy raw material liquid through a porous ceramic plate and pour it into the filter box. The temperature of the filter box is set at 900°C to 1000°C;

(4) Casting: Pour the alloy raw material liquid in the filter box into the crystallizer for continuous casting; the casting speed is 25-35L/min, the cooling liquid of the crystallizer is tap water, and the diameter drawn from the end of the crystallizer is 5-10mm alloy wire;

(5) Rolling: Cold rolling the cast alloy wire through a high-speed wire finishing mill to obtain alloy wire with a diameter of 5-9 mm;

(6) Drawing: The rolled alloy wire is drawn continuously through a drawing machine for multiple passes;

(7) Annealing: Put the drawn alloy wire into an incubator-type resistance furnace, heat it to 450-500°C, keep it warm for 2-4 hours, and then cool it to room temperature with the furnace;

(8) Finishing: put the annealed alloy wire into the straightening machine for finishing;

(9) Surface treatment: Grind the finished alloy wire with 800#, 1000# and 1200# sandpaper successively to remove surface burrs and obtain a smooth surface; then coat a layer of grease on the surface of the alloy wire , to avoid direct contact with the air and cause the surface to be oxidized;

(10) Prepare the finished wire: wind the surface-treated alloy wire on a plastic reel with a diameter of 18mm through a wire winding machine, and the weight of the wire is 12.5kg, and then pack it to obtain the finished arc sprayed solid wire ;

(11) Preparation of high-temperature oxidation-resistant coating: Arc-sprayed solid wire is deposited on the surface of the base material with a thickness of 0.5-0.9 mm of FeCrAl-based high-temperature oxidation-resistant coating through supersonic arc spraying equipment.

The technical parameters of rolling in the step (5) are: billet heating temperature 170-200°C, rolling gap 15-20s, pressure 0.4-0.8Mpa, finishing mill limited speed 85-95m/s, spinning coefficient 3.5 ~4.0.

The drawing conditions in the step (6) are as follows: the number of drawing times is 5-8 passes, the extrusion temperature is 450-500°C, the outflow die hole speed is 50-70m/min, and the lubricant is 65% cylinder oil + 15% hard oil. Lead fatty acid + 10% graphite + 10% talcum powder.

The process parameters of deposition in the step (11) are: voltage 28-34V, current 160-220A, air pressure 0.8-1.0Mpa, wire feeding speed 0.1-0.2m/s, spraying distance 10-20cm.

Beneficial effects of the present invention:

1. Compared with powder core wire, the solid wire prepared by the present invention has low manufacturing cost and simple process. The oxidation resistance of the coating prepared by arc spraying is also better than that of most Fe-based powder core coatings. After the coating is oxidized at high temperature, the oxide layer is dense and stable, and the coating density and adhesion are better than those prepared by powder core wire.

2. The present invention can change the ratio of each alloy component to prepare alloy wires with different components. By adding rare earth to the alloy, the high-temperature service life of the coating can be greatly improved, and the rare earth element can make the oxide film structure on the surface of the coating occur. The change increases the thickness of the oxide film and enhances the adhesion of the oxide film, so that the coating obtains a dense and firm oxide film, which significantly improves the high-temperature oxidation resistance of the FeCrAl alloy. Oxidation coating has excellent protective effect.

Contents of the invention

Fig. 1 is the high temperature oxidation weight gain curves of four high temperature oxidation resistant coatings of the present invention and No. 20 steel substrate.

Fig. 2 is the hot corrosion weight gain curve of four kinds of high temperature oxidation resistant coatings of the present invention and No. 20 steel substrate.

detailed description

A method for preparing a high-temperature oxidation-resistant coating by electric arc spraying a solid wire, comprising the following steps:

1. Ingredients: Alloy raw material Fe powder, Cr powder, Al powder, Si powder, C powder and Y ₂ O ₃ and CeO ₂ powder mixed in 1:1 to prepare A, B, C, D four groups of FeCArAl according to different components base alloy, the specific ratio is shown in Table 1; the A combination alloy is recorded as FeCr ₂₀ Al ₆ Re _0.15 , the B combination alloy is recorded as FeCr ₂₅ Al ₆ Re _0.15 , the C combination alloy is recorded as FeCr ₂₅ Al ₈ Re _0.15 , the D combination Gold is recorded as FeCr ₂₅ Al ₈ Re _0.3 ;

2. Melting: Put the prepared alloy raw materials into a vacuum induction furnace for melting, preheat to 400-550°C for 3 hours, control the temperature of the alloy liquid at 1000-1200°C during melting, and perform electromagnetic stirring every 15 minutes;

3. Filtration: Filter the smelted alloy raw material liquid through a porous ceramic plate, and pour it into the filter box. The temperature of the filter box is set at 950°C;

4. Casting: Pour the alloy raw material liquid in the filter box into the mold for continuous casting; the casting speed is 30L/min, the cooling liquid of the mold is tap water, and the alloy wire with a diameter of 6mm is pulled out from the end of the mold;

5. Rolling: The cast alloy wire is cold-rolled in a high-speed wire finishing mill to obtain alloy wire with a diameter of 5.5 mm; the rolling process parameters are: billet heating temperature 170-200°C The gap is 15-20s, the pressure is 0.5-0.6Mpa, the limited speed of the finishing mill is 90m/s, and the spinning coefficient is 3.5-4.0;

6. Drawing: The rolled alloy wire is continuously drawn through a drawing machine for multiple passes; the drawing conditions are: drawing times 6 passes, extrusion temperature 450-500°C, outflow die hole speed 60m /min, the lubricant is 65% cylinder oil + 15% lead stearate + 10% graphite + 10% talcum powder;

7. Annealing: Put the drawn alloy wire into an incubator-type resistance furnace, heat it to 450-500°C, keep it warm for 3 hours, and then cool it to room temperature with the furnace;

8. Finishing: put the annealed alloy wire into the straightening machine for finishing;

9. Surface treatment: Grind the finished alloy wire with 800#, 1000# and 1200# sandpaper successively to remove surface burrs and obtain a smooth surface; then coat a layer of grease on the surface of the alloy wire, Avoid direct contact with air to cause the surface to be oxidized;

10. Prepare the finished wire: wind the surface-treated alloy wire on a plastic reel with a diameter of 18mm through a wire winding machine, the weight of the wire is 12.5kg, and then pack it to obtain the finished arc sprayed solid wire;

11. Preparation of high-temperature oxidation-resistant coating: arc-sprayed solid wire is deposited on the surface of No. 20 steel substrate through supersonic arc spraying equipment. The deposition process parameters are: voltage 28-34V, current 160-220A, air pressure 0.8-1.0 Mpa, the wire feeding speed is 0.1-0.15m/s, the spraying distance is 15cm, and the FeCrAl-based high-temperature oxidation-resistant coating of 0.5-0.9mm is prepared.

Table 1 The ratio of each component in the FeCrAl-based alloy.

Through the above steps, four high-temperature oxidation-resistant coatings of FeCr ₂₀ Al ₆ Re _0.15 , FeCr ₂₅ Al ₆ Re _0.15 , FeCr ₂₅ Al ₈ Re _0.15 and FeCr ₂₅ Al ₈ Re _0.3 were respectively prepared, and the coating properties were tested, including High temperature oxidation (temperature 900°C, time 100h) and thermal corrosion (Na ₂ SO ₄ +K ₂ SO ₄ molar ratio 7:3; coating amount 2.5mg/cm ² , corrosion temperature 800°C, corrosion time 100h), the test results are as follows Figure 1 and Figure 2 show.

It can be seen from Figure 1 that after high temperature oxidation at 900 °C for 100 h, the substrate of No. 20 steel has a large weight gain, and the oxidation weight gain curves of the four coatings are relatively flat, with less oxidation gain; among them, the oxidation gain of steel No. 20 183.9mg/cm ² , FeCr ₂₀ Al ₆ Re _0.15 oxidation weight gain is 57.5 mg/cm ² , FeCr ₂₅ Al ₆ Re _0.15 oxidation weight gain is 43.6 mg/cm ² , FeCr ₂₅ Al ₈ Re _0.15 oxidation weight gain is 31.1 mg/cm ² , FeCr ₂₅ Al ₈ Re _0.3 oxidation weight gain is 4.2 mg/cm ² .

It can be seen from Figure 2 that after hot corrosion at 900°C for 100 hours, the corrosion gain of No. 20 steel was 251.2 mg/cm ² , the corrosion gain of FeCr ₂₀ Al ₆ Re _0.15 was 81.8 mg/cm ² , and the corrosion gain of FeCr ₂₅ Al ₆ Re _0.15 was 251.2 mg/cm 2 . The weight is 18.1 mg/cm ² , the corrosion gain of FeCr ₂₅ Al ₈ Re _0.15 is 9.6 mg/cm ² , and the corrosion gain of FeCr ₂₅ Al ₈ Re _0.3 is 2.8 mg/cm ² .

In summary, the four coatings all have good resistance to high temperature oxidation and hot corrosion, and can play a good role in protecting the No. 20 steel substrate. Among them, the coating with the best performance is FeCr ₂₅ Al ₈ Re _0.3 , comprehensive properties of the coating FeCr ₂₅ Al ₈ Re _0.3 > FeCr ₂₅ Al ₈ Re _0.15 > FeCr ₂₅ Al ₆ Re _0.15 > FeCr ₂₀ Al ₆ Re _0.15 , indicating that the increase of rare earth content is beneficial to improve the oxidation resistance of the coating and thermal corrosion resistance.

The above is only a specific implementation of the present invention, but the scope of protection of the present invention is not limited thereto, and any changes or simple replacements that do not go through creative work should be covered within the scope of protection of the present invention.

Claims (9)

1. An arc-sprayed solid wire, characterized in that: the solid wire is a FeCrAl-based alloy, composed of the following raw materials by weight percentage: Cr19～26wt%, Al5～9 wt%, Si0.05～0.08wt%, C0 .05～0.08wt%, rare earth oxide Y ₂ O ₃ and CeO ₂ mixture 0.1～0.5wt%, Fe balance; In the rare earth oxide Y ₂ O ₃ and CeO ₂ mixture, the ratio of Y ₂ O ₃ to CeO ₂ is 1:1. 2. The arc sprayed solid wire according to claim 1, characterized in that: the solid wire is a FeCrAl-based alloy, composed of the following raw materials by weight percentage: Cr19～21wt%, Al5～7 wt%, Si0.05～ 0.08wt%, C0.05~0.08wt%, rare earth oxide Y ₂ O ₃ and CeO ₂ mixture 0.1~0.2wt%, Fe balance. 3. The electric arc spraying solid wire according to claim 1, characterized in that: the solid wire is a FeCrAl-based alloy, composed of the following raw materials by weight percentage: Cr23~26wt%, Al5~7 wt%, Si0.05~ 0.08wt%, C0.05~0.08wt%, rare earth oxide Y ₂ O ₃ and CeO ₂ mixture 0.1~0.2wt%, Fe balance. 4. The arc sprayed solid wire according to claim 1, characterized in that: the solid wire is a FeCrAl-based alloy, composed of the following raw materials by weight percentage: Cr23~26wt%, Al7~9 wt%, Si0.05~ 0.08wt%, C0.05~0.08wt%, rare earth oxide Y ₂ O ₃ and CeO ₂ mixture 0.1~0.2wt%, Fe balance. 5. The arc sprayed solid wire according to claim 1, characterized in that: the solid wire is a FeCrAl-based alloy, composed of the following raw materials by weight percentage: Cr23-26wt%, Al7-9 wt%, Si0.05- 0.08wt%, C0.05~0.08wt%, rare earth oxide Y ₂ O ₃ and CeO ₂ mixture 0.3~0.5wt%, Fe balance. 6. A method for preparing a high-temperature oxidation-resistant coating by arc spraying a solid wire according to any one of claims 1 to 5, comprising the following steps: (1) Ingredients: Fe powder, Cr powder, Al powder, Si powder, C powder, and Y ₂ O ₃ and CeO ₂ powder mixed in a ratio of 1:1 are mixed according to the above ratio, and mixed evenly; (2) Melting: Put the prepared alloy raw materials into a vacuum induction furnace for melting, preheat to 400-550°C for 2-4 hours, and control the temperature of the alloy liquid at 1000-1200°C during melting, every 10-20min carry out electromagnetic stirring; (3) Filtration: Filter the smelted alloy raw material liquid through a porous ceramic plate and pour it into the filter box. The temperature of the filter box is set at 900°C to 1000°C; (4) Casting: Pour the alloy raw material liquid in the filter box into the crystallizer for continuous casting; the casting speed is 25-35L/min, the cooling liquid of the crystallizer is tap water, and the diameter drawn from the end of the crystallizer is 5-10mm alloy wire; (5) Rolling: Cold rolling the cast alloy wire through a high-speed wire finishing mill to obtain alloy wire with a diameter of 5-9mm; (6) Drawing: The rolled alloy wire is drawn continuously through a drawing machine for multiple passes; (7) Annealing: Put the drawn alloy wire into an incubator-type resistance furnace, heat it to 450-500°C, keep it warm for 2-4 hours, and then cool it to room temperature with the furnace; (8) Finishing: put the annealed alloy wire into the straightening machine for finishing; (9) Surface treatment: Grind the finished alloy wire with 800#, 1000# and 1200# sandpaper successively to remove surface burrs and obtain a smooth surface; then coat a layer of grease on the surface of the alloy wire , to avoid direct contact with the air and cause the surface to be oxidized; (10) Finished wire: Wind the surface-treated alloy wire on a plastic reel with a diameter of 18mm through a wire winding machine, and the weight of the wire is 12.5kg, and then pack it to make the finished arc sprayed solid wire ; (11) Preparation of high-temperature oxidation-resistant coating: Arc-sprayed solid wire is deposited on the surface of the base material with a thickness of 0.5-0.9 mm of FeCrAl-based high-temperature oxidation-resistant coating through supersonic arc spraying equipment. 7. The method for preparing a high-temperature oxidation-resistant coating by arc spraying a solid wire according to claim 6, characterized in that: the rolling process parameters in the step (5) are: blank heating temperature 170-200°C, The rolling gap is 15-20s, the pressure is 0.4-0.8Mpa, the limit speed of the finishing mill is 85-95m/s, and the spinning coefficient is 3.5-4.0. 8. The method for preparing a high-temperature oxidation-resistant coating by arc spraying solid wire according to claim 6, characterized in that: the drawing conditions in the step (6) are: drawing times 5-8 passes, extrusion The temperature is 450-500°C, the outflow speed of the die hole is 50-70m/min, and the lubricant is 65% cylinder oil + 15% lead stearate + 10% graphite + 10% talcum powder. 9. The method for preparing a high-temperature oxidation-resistant coating by arc spraying solid wire according to claim 6, characterized in that: the process parameters deposited in the step (11) are: voltage 28-34V, current 160-220A, The air pressure is 0.8-1.0Mpa, the wire feeding speed is 0.1-0.2m/s, and the spraying distance is 10-20cm.