CN105908018B - A kind of composite thermal spraying powder and its preparation method - Google Patents

Abstract

The invention discloses a composite thermal spraying powder and a preparation method thereof. The main components contained in the powder are: 2-7wt.% aluminum Al, 40-75wt.% chromium Cr, 0.1-0.3wt.% Boron B, 3-8wt.% carbon C, and nickel Ni as the balance; and the particle size of the powder is: 5-125 μm, and the main particle size is 15-75 μm; the main particle size means that the powder within this particle size range accounts for 60% above. The powder has high sphericity, uniform composition, low oxygen content, controllable preparation process, high content of chromium carbide in the powder, and is precipitated in a long strip in an in-situ autogenous manner.

Description

A kind of composite thermal spraying powder and its preparation method

technical field

The invention relates to the technical fields of powder processing and metal coating materials, in particular to a composite thermal spraying powder and a preparation method thereof.

Background technique

The failure of modern industrial parts often occurs on the surface of the parts. Therefore, the use of advanced surface treatment technology (such as thermal spraying) to prepare key coatings on the surface of parts or to repair the coating on the failed surface will largely On the one hand, it can meet the use requirements of parts for different working conditions and improve the service life of parts. However, with the further development of modern manufacturing industry, the application conditions of industrial parts are becoming increasingly harsh, and it is difficult for coatings prepared with single-structure metal or alloy materials to meet the increasingly complex requirements for wear and corrosion resistance. The ceramic-metal composite material strengthened by the ceramic relative to the metal phase is widely used in automobiles (such as piston rings) because it combines the characteristics of high hardness, high melting point, corrosion resistance of the ceramic phase and high toughness and easy processing of the metal phase. ), aerospace (such as aircraft landing gear), metallurgy (such as sinking rolls) and papermaking (such as corrugated rolls) and other industrial or civil components that have high requirements for surface wear and corrosion resistance. Commonly used ceramic-reinforced metal composite materials include WC-Co, Cr ₃ C ₂ -NiCr, etc., but because WC ceramics will be oxidized and decomposed at working conditions above 550 °C, they cannot be used in medium and high temperature applications, and Cr ₃ C ₂ The performance can be kept stable below 800℃, but the performance of the metal phase NiCr will decrease obviously with the increase of temperature. Therefore, in view of the wear resistance and corrosion resistance of some parts, such as the crankshaft, exhaust valve and piston ring of large heavy-duty marine diesel engines, it is urgent to prepare a new type of metal-ceramic Composite materials and corresponding coatings to meet its use requirements and improve its service life.

In the prior art, in the composite powder used in the preparation of ceramic-reinforced metal composite coatings, the ceramic phase is often added by external addition. Generally, ceramic particles and metal particles are mixed directly or the two are mixed and then agglomerated and sintered. This type of ceramic phase The composition of the externally added composite powder is not uniform, the bonding between the ceramic phase and the metal phase is poor, and the ceramic phase is easy to scatter or degrade during the spraying process, resulting in problems such as low spraying deposition rate and poor coating performance. Moreover, since the externally added ceramic phase often adopts ceramic particles with polygonal edges and corners, it is easy to cause excessive wear of the abrasive material during the subsequent wear process when deposited into the coating.

Contents of the invention

The purpose of the present invention is to provide a composite thermal spraying powder and its preparation method. The powder has high sphericity, uniform composition, low oxygen content, controllable preparation process, high chromium carbide content in the powder, and is in the form of long strips in an in-situ autogenous manner. Precipitate out.

A composite thermal spraying powder, the main components contained in the powder are:

2-7wt.% aluminum Al, 40-75wt.% chromium Cr, 0.1-0.3wt.% boron B, 3-8wt.% carbon C, and nickel Ni as the balance;

And the particle size of the powder is: 5-125 μm, and the main particle size is 15-75 μm; the main particle size means that the powder within the particle size range accounts for more than 60%.

A preparation method of composite thermal spray powder, said preparation method comprising:

First, the raw materials are extracted according to the set mass ratio; wherein, the extracted raw materials include: 2-7wt.% aluminum Al, 40-75wt.% chromium Cr, 0.1-0.3wt.% boron B, 3-8wt. .% carbon C, the balance is nickel Ni;

The extracted raw materials are put into a vacuum melting crucible, and the Ni ₃ Al-based alloy powder with chromium carbide in-situ autogenous reinforcement is obtained by vacuum induction melting-inert gas atomization;

The obtained alloy powder is subjected to vibratory screening or airflow classification treatment to prepare the thermal spraying powder of the chromium carbide in situ autogenously reinforced Ni ₃ Al base alloy.

The content of the obtained in-situ authigenic chromium carbide is 35-85vol.%.

And the structure is composed of one or more of Cr ₇ C ₃ , Cr ₃ C ₂ , Cr ₂₃ C ₆ , and the shape is long strip.

The boron in the raw material is nickel-boron alloy, chromium-boron alloy or a mixture of the two; and the content of boron in the alloy is 18-21wt.%.

The vacuum induction smelting-inert gas atomization method is specifically:

Firstly, the raw material is heated and refined in an intermediate frequency induction furnace. The vacuum degree in the furnace is ≤10Pa, and the heating rate is 5-20°C/min. 1600 ℃ ~ 1700 ℃, followed by heat preservation treatment, the heat preservation time is 30 ~ 90min, electromagnetic stirring is carried out at the same time during the heat preservation process, the frequency of the electromagnetic stirrer is 3000 ~ 5000Hz, after the raw material alloy liquid is uniform, it enters the atomization tank through the tundish and the leak nozzle middle;

Then, the alloy liquid is atomized and solidified by means of inert gas atomization, and at the same time, chromium carbide is spontaneously precipitated in situ to obtain _Ni3Al -based alloy powder enhanced by chromium carbide in situ.

The diameter of the leak nozzle is 2-8 mm, and the inert atomizing gas used is argon or nitrogen;

The atomizing nozzle adopts retractable circular seam nozzle, the atomizing cone angle is 40-80°, and the atomizing pressure is 2.5-5MPa.

The method also includes:

Further use the obtained chromium carbide in-situ self-generated reinforced Ni ₃ Al-based alloy thermal spray powder to prepare a composite coating, the thermal spraying method used includes but not limited to plasma spraying process or supersonic flame spraying process, wherein:

In the plasma spraying process: spraying power 30-50Kw, argon flow rate 35-50l/min, hydrogen flow rate 5-9l/min, powder feeding rate 30-65g/min, spraying distance 100-140mm;

In the supersonic flame spraying process: the kerosene flow rate is 22-30l/h, the oxygen flow rate is 800-1000l/h, the powder feeding rate is 45-80g/min, and the spraying distance is 350-400mm.

The prepared composite coating has a thickness of 0.1-1 mm, a microhardness range of Hv _0.3 500-Hv _0.3 1100, and a bonding strength range of 30-85 MPa.

It can be seen from the above-mentioned technical solution provided by the present invention that the powder has high sphericity, uniform composition, low oxygen content, controllable preparation process, high content of chromium carbide in the powder, and is precipitated in strips in an in-situ autogenous manner; And it can make the prepared coating have excellent bonding, and has the characteristics of high hardness, low friction coefficient, good wear resistance, excellent corrosion resistance and erosion resistance in the range of 25 ° C to 700 ° C.

Description of drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the accompanying drawings that need to be used in the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For Those of ordinary skill in the art can also obtain other drawings based on these drawings on the premise of not paying creative efforts.

Fig. 1 is a schematic flow chart of the preparation method of the composite thermal spray powder provided by the embodiment of the present invention.

detailed description

The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.

The embodiment of the present invention provides a composite thermal spraying powder, the main components contained in the powder are:

2-7wt.% aluminum Al, 40-75wt.% chromium Cr, 0.1-0.3wt.% boron B, 3-8wt.% carbon C, and nickel Ni as the balance;

And the particle size of the powder is: 5-125 μm, and the main particle size is 15-75 μm; here, the main particle size means that the powder within the particle size range accounts for more than 60%.

The embodiment of the present invention also provides a preparation method of composite thermal spray powder, as shown in Figure 1 is a schematic flow chart of the preparation method provided by the embodiment of the present invention, the preparation method includes:

Step 11: first extract the raw materials according to the set mass ratio;

In this step, the extracted raw materials include: 2-7wt.% aluminum Al, 40-75wt.% chromium Cr, 0.1-0.3wt.% boron B, 3-8wt.% carbon C, and The amount is nickel Ni;

The boron in the raw material is nickel-boron alloy, chromium-boron alloy or a mixture of the two; and the content of boron in the alloy is 18-21wt.%.

Step 12: Put the extracted raw materials into a vacuum melting crucible, and obtain Ni ₃ Al-based alloy powder with chromium carbide in situ autogenous reinforcement by means of vacuum induction melting-inert gas atomization;

In this step, the content of the obtained in-situ authigenic chromium carbide is 35-85vol.%, and the structure is composed of one or more of Cr ₇ C ₃ , Cr ₃ C ₂ , Cr ₂₃ C ₆ , The shape is long strip.

Here, the above vacuum induction melting-inert gas atomization method is specifically:

Firstly, the raw material is heated and refined in an intermediate frequency induction furnace. The vacuum degree in the furnace is ≤10Pa, and the heating rate is 5-20°C/min. 1600 ℃ ~ 1700 ℃, followed by heat preservation treatment, the heat preservation time is 30 ~ 90min, electromagnetic stirring is carried out at the same time during the heat preservation process, the frequency of the electromagnetic stirrer is 3000 ~ 5000Hz, after the raw material alloy liquid is uniform, it enters the atomization tank through the tundish and the leak nozzle middle;

Then, the alloy liquid is atomized and solidified by means of inert gas atomization, and at the same time, chromium carbide is spontaneously precipitated in situ to obtain _Ni3Al -based alloy powder enhanced by chromium carbide in situ.

In the specific implementation process, the diameter of the above-mentioned leakage nozzle can be 2-8 mm, and the inert atomizing gas used can be argon or nitrogen; the atomizing nozzle is a retractable annular nozzle, and the atomization cone angle is 40-80°. The atomization pressure is 2.5~5MPa.

Step 13: Vibrating sieving or airflow classification treatment is performed on the obtained alloy powder to prepare a thermal spraying powder of Ni ₃ Al-based alloy reinforced by chromium carbide in situ.

In addition, after obtaining the thermal spraying powder of the above-mentioned chromium carbide in-situ self-reinforced Ni ₃ Al-based alloy, the thermal spraying powder obtained can also be used to prepare a composite coating. The thermal spraying method used includes but is not limited to plasma spraying process or supersonic flame spraying process in which:

In the plasma spraying process: spraying power 30-50Kw, argon flow rate 35-50l/min, hydrogen flow rate 5-9l/min, powder feeding rate 30-65g/min, spraying distance 100-140mm;

In the supersonic flame spraying process: the kerosene flow rate is 22-30l/h, the oxygen flow rate is 800-1000l/h, the powder feeding rate is 45-80g/min, and the spraying distance is 350-400mm.

The thickness of the finally obtained composite coating can be 0.1-1 mm, the microhardness can be in the range of Hv _0.3 500-Hv _0.3 1100, and the bonding strength can be in the range of 30-85 MPa.

The preparation process of above-mentioned thermal spraying powder and composite coating is described in detail below in conjunction with specific examples:

Example 1, at first get raw material by following mass ratio, aluminum Al: 5.2wt.%, chromium Cr: 55.3wt.%, boron B: 0.21wt.%, carbon C: 5.0wt.%, nickel Ni: surplus; And A nickel plate, a nickel-boron alloy block, a chromium block, and a graphite block are sequentially put into the vacuum melting crucible.

Then use an intermediate frequency induction furnace to heat and refine the raw materials. The vacuum degree in the furnace is 9.6Pa, and the heating rate is 15°C/min. Insulation treatment, the holding time is 45min, the frequency of the electromagnetic stirrer is 4000Hz, during which aluminum blocks are added step by step for smelting;

The obtained alloy liquid enters the atomization tank through the tundish and the leak nozzle for high-pressure argon atomization. The diameter of the leak nozzle is 4 mm, the atomization cone angle is 60°, and the atomization pressure is 3.5 MPa. The atomized powder is subjected to airflow classification treatment to obtain the composite thermal spraying powder of the chromium carbide in-situ self-generated reinforced Ni ₃ Al-based alloy, and the particle size distribution of the powder is: 10-105 μm.

The obtained powder has high sphericity and low oxygen content of 400ppm, and the chromium carbide in the powder is elongated and uniformly distributed with a content of 63vol.%.

Further, supersonic flame spraying is used to spray the composite powder of chromium carbide in-situ self-reinforced Ni ₃ Al-based alloy prepared above to prepare a composite coating of chromium carbide in-situ self-generated reinforced Ni ₃ Al-based alloy. The specific spraying process parameters It is: kerosene flow rate 26l/h, oxygen flow rate 900l/h, powder feeding rate 50g/min, spraying distance 380mm.

The final prepared coating structure is uniform and dense, the microhardness of the coating at room temperature is Hv _0.3 1011.1, the bonding strength is 80.24MPa, and the microhardness at 700°C is Hv ₁ 755.6.

Example 2, at first get raw material by following mass ratio, aluminum Al: 3.8wt.%, chromium Cr: 66.8wt.%, boron B: 0.23wt.%, carbon C: 6.0wt.%, nickel Ni: surplus; A nickel plate, a nickel-boron alloy block, a chromium block, and a graphite block are sequentially put into the vacuum melting crucible.

Then use an intermediate frequency induction furnace to heat and refine the raw materials. The vacuum degree in the furnace is 9.7Pa, and the heating rate is 15°C/min. For 20 minutes, the frequency of the electromagnetic stirrer is 5000Hz, during which aluminum blocks are added step by step for smelting;

The obtained alloy liquid enters the atomization tank through the tundish and the leak nozzle for high-pressure argon atomization. The diameter of the leak nozzle is 5 mm, the atomization cone angle is 65°, and the atomization pressure is 4.0 MPa. Vibrating, sieving and classifying the atomized powder to obtain a composite thermal spraying powder of chromium carbide in-situ self-generated reinforced Ni ₃ Al-based alloy, and the particle size distribution of the powder is: 15-115 μm.

The obtained powder has a high sphericity and a low oxygen content of 450 ppm. The chromium carbide in the powder is strip-shaped and evenly distributed with a content of 76 vol.%.

Further, supersonic flame spraying is used to spray the composite powder of chromium carbide in-situ self-reinforced Ni ₃ Al-based alloy prepared above to prepare a composite coating of chromium carbide in-situ self-generated reinforced Ni ₃ Al-based alloy. The specific spraying process parameters For: kerosene flow rate 28l/h, oxygen flow rate 950l/h, powder feeding rate 45g/min, spraying distance 370mm.

The final prepared coating structure is uniform and dense, the microhardness of the coating at room temperature is Hv _0.3 1031.4, the bonding strength is 79.76MPa, and the microhardness at 700°C is Hv ₁ 799.6.

Table 1 below shows the microhardness in the range of 25 to 700°C for the composite coating of chromium carbide in-situ self-reinforced Ni ₃ Al-based alloy prepared in Examples 1 and 2 and the existing commercial Cr ₃ C ₂ -NiCr coating (Hv ₁ ) vs.:

Table 1

As shown in Table 2 below, the composite coatings of the chromium carbide in situ self-reinforced Ni ₃ Al-based alloys prepared by examples 1 and 2 and the existing commercial Cr ₃ C ₂ -NiCr coatings have better friction coefficients and wear resistance (including their own Contrast of wear amount and wear amount of abrasive parts):

Table 2

Among them, the friction and wear test adopts German IV high-temperature reciprocating friction and wear testing machine, the coating is a constant moving upper sample, and the abrasive part is a static lower sample, the test load is 100N, the frequency is 50Hz, the stroke is 2mm, the wear time is 30min, and the temperature is normal temperature, respectively. 300°C, 600°C. The abrasive part for the test at room temperature and 300°C is gray cast iron, and the abrasive part for the test at 600°C is 304 stainless steel.

From the above comparison, it can be seen that the microhardness of this coating ranges from Hv _0.3 500 to Hv _0.3 1100, and the bonding strength ranges from 30 to 85 MPa. Anti-friction, wear-resistant, corrosion-resistant, anti-scouring and other occasions within the range of ~800 °C.

In summary, the powder described in the embodiment of the present invention has high sphericity, uniform composition, low oxygen content, controllable preparation process, high content of chromium carbide in the powder, and is precipitated in a long strip in an in-situ autogenous manner; and can The prepared coating has excellent bonding, and has the characteristics of high hardness, low friction coefficient, good wear resistance, excellent corrosion resistance and erosion resistance in the range of 25°C to 700°C.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person familiar with the technical field can easily conceive of changes or changes within the technical scope disclosed in the present invention. Replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (5)

1. a preparation method of composite thermal spraying powder, is characterized in that, described preparation method comprises: First, the raw materials are extracted according to the set mass ratio; wherein, the extracted raw materials include: 2-7wt.% aluminum Al, 40-75wt.% chromium Cr, 0.1-0.3wt.% boron B, 3-8wt. .% carbon C, the balance being nickel Ni; the boron in the raw material is nickel-boron alloy, chromium-boron alloy or a mixture of the two; and the content of boron in the alloy is 18-21wt.%. Put the extracted raw materials into a vacuum melting crucible, and use vacuum induction melting-inert gas atomization to obtain Ni ₃ Al-based alloy powder with chromium carbide in situ autogenous reinforcement; wherein, the obtained in situ autogenous chromium carbide content 35~85vol.%; and the structure is composed of one or more of Cr ₇ C ₃ , Cr ₃ C ₂ , Cr ₂₃ C ₆ , and the shape is long strip; The obtained alloy powder is subjected to vibratory sieving or airflow classification treatment to prepare thermal spraying powder of chromium carbide in-situ self-reinforced Ni ₃ Al-based alloy, and the particle size of the powder is: 5-125 μm, and the main particle size is 15- 75 μm; the main particle size means that the powder within this particle size range accounts for more than 60%. 2. the preparation method of composite thermal spraying powder as claimed in claim 1, is characterized in that, the mode of described vacuum induction melting-inert gas atomization is specifically: Firstly, the raw material is heated and refined in an intermediate frequency induction furnace. The vacuum degree in the furnace is ≤10Pa, and the heating rate is 5-20°C/min. 1600 ℃ ~ 1700 ℃, followed by heat preservation treatment, the heat preservation time is 30 ~ 90min, electromagnetic stirring is carried out at the same time during the heat preservation process, the frequency of the electromagnetic stirrer is 3000 ~ 5000Hz, after the raw material alloy liquid is uniform, it enters the atomization tank through the tundish and the leak nozzle middle; Then, the alloy liquid is atomized and solidified by means of inert gas atomization, and at the same time, chromium carbide is spontaneously precipitated in situ to obtain Ni ₃ Al-based alloy powder reinforced by in situ chromium carbide. 3. the preparation method of composite thermal spraying powder as claimed in claim 2, is characterized in that, The diameter of the leak nozzle is 2-8 mm, and the inert atomizing gas used is argon or nitrogen; The atomizing nozzle adopts retractable circular seam nozzle, the atomizing cone angle is 40-80°, and the atomizing pressure is 2.5-5MPa. 4. the preparation method of composite thermal spray powder as claimed in claim 1, is characterized in that, described method also comprises: Further use the obtained chromium carbide in-situ self-generated reinforced Ni ₃ Al-based alloy thermal spray powder to prepare a composite coating, the thermal spraying method used includes but not limited to plasma spraying process or supersonic flame spraying process, wherein: In the plasma spraying process: spraying power 30-50kW, argon gas flow rate 35-50L/min, hydrogen gas flow rate 5-9L/min, powder feeding rate 30-65g/min, spraying distance 100-140mm; In the supersonic flame spraying process: the kerosene flow rate is 22-30L/h, the oxygen flow rate is 800-1000L/h, the powder feeding rate is 45-80g/min, and the spraying distance is 350-400mm. 5. the preparation method of composite thermal spraying powder as claimed in claim 4, is characterized in that, The prepared composite coating has a thickness of 0.1-1 mm, a microhardness range of Hv _0.3 500-Hv _0.3 1100, and a bonding strength range of 30-85 MPa.