CN114318202B - A kind of nickel-based alloy surface wear-resistant coating and preparation method thereof - Google Patents

Abstract

The invention discloses a nickel-based alloy surface wear-resistant coating and a preparation method thereof, wherein the wear-resistant coating comprises a nickel-based alloy matrix, and Al is grown on the surface of the nickel-based alloy matrix in situ ₂ O ₃ Ceramic layer and WS with lubrication function ₂ Wear-resistant coating of particles, WS ₂ Particles are dispersed in Al ₂ O ₃ In the ceramic layer. Polishing the surface of the nickel-based alloy, corroding the nickel-based alloy by acid liquor, immersing the nickel-based alloy into molten aluminum liquor to form an aluminum-immersed layer, and annealing the nickel-based alloy in argon to form a NiAl diffusion layer; then at Na-containing ₂ WO ₄ And Na (Na) ₂ S, constant-current micro-arc oxidation treatment with sectional forward/reverse current cooperative control is carried out in phosphate aqueous solution, and wear-resistant ceramic Al is formed on the surface in situ ₂ O ₃ And lubrication function WS ₂ And (3) compounding the reinforced wear-resistant coating. According to the invention, through the dual functions of the NiAl diffusion layer and the constant-current micro-arc oxidation process with sectional forward/reverse current cooperative control, the nickel-based alloy is promoted to form a layered friction layer in the friction process, the friction coefficient of the nickel-based alloy is effectively reduced, and the strengthening effect of the ceramic phase improves the wear resistance.

Description

A kind of nickel-based alloy surface wear-resistant coating and preparation method thereof

technical field

The invention belongs to a nickel-based alloy surface coating and its preparation, in particular to a nickel-based alloy surface wear-resistant coating and a preparation method thereof.

Background technique

Because of its good mechanical properties and corrosion resistance, nickel-based alloys are widely used in equipment manufacturing materials in the chemical energy industry, nuclear energy industry, transportation and other fields, such as engine turbine parts, continuous casting machine rolls, extrusion dies, etc. . Under the condition of reciprocating transmission, the nickel-based alloy is prone to friction and wear, and it is difficult to form a film and is very prone to failure. Therefore, insufficient wear resistance makes it difficult to meet the requirements of the abrasive working environment, and increases the frequency of parts replacement. At present, the wear resistance of nickel-based alloys is mainly enhanced by ceramic phases and surface modification methods: first, wear-resistant phases represented by graphite and ceramic phases are added to the nickel-based alloy matrix, and the powder metallurgy process is used to improve the wear resistance of nickel-based alloys. Forming nickel-based composite materials, but the bonding strength between the above-mentioned reinforcement phase and the nickel-base alloy interface is weak, and at the same time, it is difficult to control the distribution state of the reinforcement phase in the nickel-base alloy, and it is difficult to effectively improve the wear resistance of the nickel-base alloy. On the other hand, surface modification technology provides a way to improve the wear resistance of nickel-based alloys. For example, surface chemical heat treatments such as nitriding, carburizing, and boronizing can improve the surface hardness and wear resistance of metal materials, but penetration The layer is thin and it is difficult to meet the long-term wear requirements, which limits the wide application of nickel-based alloys.

Contents of the invention

Purpose of the invention: the first purpose of the present invention is to provide a kind of nickel base alloy surface wear-resistant coating; Another purpose of the present invention is to provide the preparation method of this wear-resistant coating.

Technical solution: A wear-resistant coating on the surface of a nickel-based alloy of the present invention includes a nickel-based alloy substrate, and the _surface of the nickel-based alloy substrate is in-situ grown on the surface of the _Al2O3 ceramic layer and _WS2 particles with a lubricating function wear-resistant coating, the WS ₂ particles are dispersed in the Al ₂ O ₃ ceramic layer.

Among them, the Al ₂ O ₃ and WS ₂ composite coating is formed in situ by micro-arc oxidation in a mixed aqueous solution of Na ₂ WO ₄ and Na ₂ S by dipping the aluminum layer on the surface of the nickel-based alloy.

The invention also protects a method for preparing a wear-resistant coating on the surface of a nickel-based alloy, comprising the following steps:

(1) Pre-treat the nickel-based alloy, and then corrode the surface with dilute hydrofluoric acid solution to obtain a rough surface;

(2) Using the hot-dip aluminum process assisted by inert argon, the aluminum-dipped layer is prepared on the surface of the nickel-based alloy with a rough surface, and the aluminum-dipped layer is annealed in an argon-protected environment to make the aluminum-dipped layer and the nickel-based alloy Form a NiAl diffusion layer;

(3) Mix Na ₂ WO ₄ , Na ₂ S, Na ₃ PO ₄ and NaOH in water to form a mixed solution;

(4) Place the nickel-based alloy immersion aluminum layer in step (2) in the mixed solution of step (3), and perform oxidation treatment with a constant current micro-arc oxidation process controlled by segmented forward/reverse current coordination. A wear-resistant coating with composite strengthening of Al ₂ O ₃ ceramic layer and WS ₂ particles was formed on the surface of the aluminum layer in situ.

Further, in the step (2), the hot-dip aluminum process assisted by inert argon gas specifically includes: heating pure aluminum with a purity of 99.5% in a vacuum furnace to 690-720°C to obtain pure aluminum liquid; Pour argon into the furnace until the pressure in the furnace is 0.1-0.2 MPa, and immerse the nickel-based alloy with a rough surface in the pure aluminum liquid for 10-30 minutes.

Further, in the step (2), the annealing temperature is 250-400° C., and the annealing time is 1-2 h.

Further, in the step (2), the thickness of the aluminum-impregnated layer is 500-1000 μm.

Further, in the step (3), the mass ratio of Na ₂ WO ₄ , Na ₂ S, Na ₃ PO ₄ and NaOH is 6-10:10-20:7-12:1-1.5.

Further, in the step (4), the constant-current micro-arc oxidation process with segmental forward/reverse current cooperative control is specifically: the forward current density is 2-4A/cm ³ within the time range of 0-50s, The reverse current density is 1.5-2A/cm ³ ; after 50s, the forward current density is 3-5A/cm ³ and the reverse current density is 2-2.5A/cm ³ .

Further, in the step (1), the pretreatment specifically refers to: polishing the nickel-based alloy to a mirror surface with sandpaper and diamond abrasive paste.

Further, in the step (1), the etching time is 3-10s.

Further, the nickel-based alloy is any one of Ni-Cr alloy, Ni-Cr-Mo alloy and Ni-Cr-Fe alloy.

The preparation principle of the present invention is as follows: according to the tribological performance requirements of nickel-based alloys in the service process, and according to the principle of material surface modification, the polished nickel-based alloys are corroded to form a rough surface, assisted by the pressure of inert argon , the surface of nickel-based alloy with rough surface is immersed in pure aluminum liquid for surface hot-dip aluminum, which can not only avoid the oxidation between the interface between pure aluminum and nickel-based alloy, but also enhance the wetting effect between the interface with the assistance of pressure, increasing the The mechanical bonding strength between the aluminum-immersed layer and the nickel-based alloy substrate, and the annealing treatment in an argon environment promotes the diffusion of nickel, aluminum and other atoms, and forms a NiAl diffusion layer at the interface between the aluminum-immersed layer and the nickel-based alloy substrate, which significantly enhances the interfacial bonding Strength; secondly, based on the high wear resistance of _Al2O3 ceramics and the lubricating _function of _WS2 , micro-arc oxidation treatment _was carried out in a phosphate aqueous solution containing _Na2WO4 and _Na2S to promote the in-situ formation of the aluminum-immersed layer The wear-resistant coating containing wear-resistant ceramics Al ₂ O ₃ and lubricating function WS ₂ composite strengthened, enhanced the bonding strength of the ceramic phase and the coating, and the synergy between Al ₂ O ₃ and W ₂ S in wear reduction and self-lubrication Under the action, to further improve the wear resistance of nickel-based alloys.

The present invention is based on the constant-current micro-arc oxidation process controlled by segmented forward/reverse current synergistically, on the surface of the nickel-based alloy impregnated aluminum layer, the in-situ preparation contains wear-resistant ceramics Al ₂ O ₃ and lubricating function WS ₂ composite strengthened Grinding coating, on the one hand, due to the application of segmented forward/reverse currents that are first low and then high, the pore size in the micro-arc oxidation film layer tends to be uniform; on the other hand, due to the wear-resistant strengthening effect of ceramic Al ₂ O ₃ , The self-lubricating effect of WS ₂ promotes the formation of a layered friction layer in the nickel-based alloy during the friction process, effectively reducing the friction coefficient of the nickel-based alloy, and the strengthening effect of the ceramic phase improves the wear resistance.

Beneficial effects: Compared with the prior art, the significant advantage of the present invention is that the present invention adopts the hot-dip aluminum process assisted by inert argon to prepare an aluminum-dipped layer on the surface of the corroded nickel-based alloy, and the auxiliary effect of inert argon can avoid Oxidation between the interface between pure aluminum and nickel-based alloy can also enhance the wetting effect between the interface with the assistance of pressure, enhance the mechanical bonding strength between the impregnated aluminum layer and the nickel-based alloy substrate, and form NiAl through annealing in an argon atmosphere. Diffusion layer, to further enhance the metallurgical bonding strength between the aluminum-impregnated layer and the nickel-based alloy substrate; on the other hand, the Al ₂ O ₃ formed in situ on the surface of the aluminum-impregnated layer and the lubricating function WS ₂ are compounded to strengthen the wear resistance coating, in which the WS ₂ phase and the Al ₂ O ₃ coating form a strong metallurgical bonding interface, the enhancement of the above-mentioned interface strength can significantly reduce the adhesion of the coating during the friction process, and avoid the coating due to weak interface strength. Peeling and failure, thereby improving the wear resistance of the material.

Description of drawings

Fig. 1 is the phase spectrogram that embodiment 1 makes nickel-based alloy surface wear-resistant coating;

Fig. 2 is that embodiment 2 makes the surface morphology of the wear-resistant coating on the surface of nickel base alloy;

Fig. 3 is the wear rate of the self-lubricating nickel-based alloy prepared in Examples 1-4.

Detailed ways

The technical solution of the present invention will be described in further detail below in conjunction with the accompanying drawings and embodiments.

Example 1

(1) The Ni-Cr nickel-based alloy is polished to a mirror surface with sandpaper and diamond abrasive paste, and then corroded in a dilute hydrofluoric acid solution for 3s to obtain a rough surface;

(2) Pure aluminum with a purity of 99.5% is heated to 690°C in a vacuum furnace, and an inert argon-assisted hot-dip aluminum process is used to pour argon into the vacuum furnace until the pressure in the furnace reaches 0.1MPa. The surface of the Ni-Cr nickel-based alloy with the rough surface is immersed in pure aluminum liquid for 10 minutes to prepare an aluminum-impregnated layer with a thickness of 500 μm. A NiAl diffusion layer is formed between the base alloys;

(3) Prepare a mixed aqueous solution of 6g/L Na ₂ WO ₄ , 10g/L Na ₂ S, 7g/L Na ₃ PO ₄ , and 1g/L NaOH;

(4) Use a forward current density of 2A/cm ³ and a reverse current density of 1.5A/cm 3 within the time range ^{of 0 to 50s; after 50s, use a forward current density of 3A/cm 3 and} a reverse current density of The micro-arc oxidation process of 2A/ ^cm3 oxidizes the aluminum-impregnated layer on the surface of the Ni-Cr nickel-based alloy in step (2) above in the aqueous solution of step (3), and forms in-situ on the surface of the aluminum-impregnated layer A wear-resistant coating reinforced with ceramic Al ₂ O ₃ and lubricating function W ₂ S.

It can be found from Figure 1 that in addition to the diffraction peaks of the nickel-based alloy matrix, the diffraction peaks of the hot-dipped aluminum layer and the NiAl phase are also found in the phase spectrum of the wear-resistant coating on the surface of the nickel-based alloy, indicating that in the thermal The formation of Ni in the interfacial diffusion layer between the immersion aluminum layer and the nickel-based alloy _matrix , and the diffraction peaks of the in-situ ceramics _Al2O3 and lubricating function _WS2 phases that also exist on the phase diagram, illustrate the present invention The wear-resistant coating on the surface of the nickel-based alloy and the preparation method can enhance the wettability of the interface between the coating and the nickel-based alloy, and form an oxide ceramic phase and a self-lubricating phase.

Example 2

The difference between this example and example 1 is: in step (2), pure aluminum with a purity of 99.5% is heated to 720°C in a vacuum furnace, and argon gas is injected into the vacuum furnace until the pressure in the furnace reaches 0.15MPa, and the preparation The thickness of the hot-dipped aluminum layer was 800 μm, the annealing temperature was set to 350°C, and the rest were the same as in Example 1.

From Figure 2, it can be found that WS ₂ phase particles are dispersed in the Al ₂ O ₃ ceramic coating, and the Al ₂ O ₃ ceramic coating is distributed with tiny pores.

Example 3

The difference between this example and Example 2 is: the nickel-based alloy in step (1) is Ni-Cr-Mo; the concentration of Na ₂ WO ₄ in step (3) is 8g/L, and the concentration of Na ₂ S is 16g/L ; In step 4, the forward current density is 3A/cm ³ and the reverse current density is 2A/cm 3 within the time range of 0-50s; after 50s, the forward current density is 4A/ ^{cm 3 ;} the rest are the same as in Example 2 same.

The friction coefficient of the nickel-based alloy surface wear-resistant coating prepared in Example 3 has a stable value of about 0.21 at room temperature, which is lower than the optimal friction coefficient (about 0.36) of the MoS ₂ reinforced NiCr alloy prepared by powder sintering, and is also lower than the micro Friction coefficient (0.3-0.4) of a single Al ₂ O ₃ coating obtained by arc oxidation.

Example 4

The difference between this example and Example 3 is: in step 3, the concentration of Na ₂ WO ₄ is 10 g/L, the concentration of Na ₂ S is 20 g/L, the concentration of Na ₃ PO ₄ is 12 g/L, and the concentration of NaOH is 1.5 g /L; In step (4), the forward current density is 4A/cm ³ and the reverse current density is 2A/cm ³ within the time range of 0-50s; after 50s, the forward current density is 5A/cm ³ and the reverse The current density is 2.5A/cm ³ ; the rest are the same as in Example 3.

From Figure 3, it can be found that the wear rate of the wear-resistant coating on the surface of the nickel-based alloy in Examples 1-4 is in the range of 1.6 to 2.3×10 ^-5 mm ³ /N•m, which is lower than that of the MoS ₂ reinforced NiCr alloy prepared by powder sintering Wear rate (4.6～8.1)×10 ^-5 mm ³ /N•m, this is because the in-situ ceramic Al ₂ O ₃ phase formed by micro-arc oxidation on the surface of the nickel-based alloy has high hardness and strength. In the process, the plastic deformation is difficult, and it is difficult to produce friction and adhesion, thereby reducing the wear rate; The annealing treatment of the aluminum-immersed layer promotes the formation of a NiAl diffusion layer with metallurgical bonding with the nickel-based alloy substrate, and the Al ₂ O ₃ layer formed in situ on the surface of the aluminum-immersed layer by the micro-arc oxidation process, the enhancement of the above-mentioned interface strength is significantly reduced. The adhesion of the coating during the friction process improves the wear resistance of the nickel-based alloy, further illustrating that the forming method of the wear-resistant coating on the surface of the nickel-based alloy provided by the present invention can effectively improve the friction performance of the nickel-based alloy.

Comparative example 1

The specific preparation process is the same as that in Example 1, except that in step (2), the aluminum-impregnated layer is not annealed at 250° C. for 2 h in an argon-protected environment, and the aluminum-impregnated layer is directly prepared on the surface of the Ni-Cr nickel-based alloy. And micro-arc oxidation process to prepare ceramic coatings.

Comparative example 2

The specific preparation process is the same as in Example 1, the difference is that step (3) does not use segmented forward/reverse current, directly adopts a constant current density of 2A/cm ³ for oxidation treatment, and obtains micro-arc oxidation ceramics coating.

The wear-resistant coating obtained in Comparative Example 1-2 was oxidized by micro-arc, and the wear-resistant performance was compared. In Comparative Example 1, the aluminum-immersed layer was not annealed at 250°C in an argon-protected environment, and there was no diffusion layer between the aluminum-immersed layer and the Ni-Cr nickel-based alloy substrate interface, and the interface bonding ability was reduced. Under the action of frictional shear stress cycles in the friction direction, the shear strength of aluminum in the aluminum-immersed layer is low, and the micro-arc oxidation porous coating aggravates the unevenness of the coating force, resulting in regional adhesion of the coating Wear, increased wear rate (3.8×10 ^-5 mm ³ /N•m). For the micro-arc oxidation treatment in Comparative Example 2, which does not use the segmented forward/reverse current mode, the pore size in the film layer varies in a large range, and the force is not uniform under the friction shear stress cycle during the friction process, and the stress Viscous wear is very easy to occur in a large area, which aggravates the wear of the coating (4.3×10 ^-5 mm ³ /N·m), so it can be explained that the NiAl diffusion layer formed at the interface of the aluminum layer/nickel-based alloy in the present invention and the separation The wear resistance of the coating is improved under the double action of the constant current micro-arc oxidation process controlled by the segmented forward/reverse current cooperatively.

Claims (8)

1. A preparation method of a nickel-based alloy surface wear-resistant coating is characterized in that the nickel-based alloy surface wear-resistant coating comprises a nickel-based alloy matrix, and Al is grown on the surface of the nickel-based alloy matrix in situ ₂ O ₃ Ceramic layer and WS with lubrication function ₂ Wear-resistant coating of granular composition, said WS ₂ Particles are dispersed in Al ₂ O ₃ In the ceramic layer; the preparation method comprises the following steps:

(1) Pretreating the nickel-based alloy, and then adopting a hydrofluoric acid dilute solution to carry out surface corrosion to obtain a rough surface;

(2) Preparing an aluminum dipping layer on the surface of the nickel-based alloy with the rough surface by adopting an inert argon-assisted hot dipping aluminum process, and annealing the aluminum dipping layer in an argon protection environment to form a NiAl diffusion layer between the aluminum dipping layer and the nickel-based alloy;

(3) Taking Na ₂ WO ₄ 、Na ₂ S、Na ₃ PO ₄ Mixing with NaOH in water to prepare a mixed solution;

(4) Placing the nickel-base alloy aluminum-immersed layer in the step (2) into the mixed solution in the step (3), carrying out oxidation treatment by using a sectional type constant-current micro-arc oxidation process with forward/reverse current cooperative control, and forming Al on the surface of the aluminum-immersed layer in situ ₂ O ₃ Ceramic layer and WS ₂ A particle composite reinforced wear-resistant coating;

the sectional type constant current micro-arc oxidation process with the cooperative control of forward current and reverse current specifically comprises the following steps: in the range of 0 toThe forward current density is 2-4A/cm within the 50s time range ³ The reverse current density is 1.5-2A/cm ³ The method comprises the steps of carrying out a first treatment on the surface of the After 50s, adopting forward current density of 3-5A/cm ³ The reverse current density is 2-2.5A/cm ³ 。

2. The method for preparing a wear-resistant coating on a nickel-based alloy surface according to claim 1, wherein in the step (2), an inert argon-assisted hot dip aluminizing process is adopted, which specifically comprises: heating pure aluminum with purity of 99.5% to 690-720 ℃ in a vacuum furnace to obtain pure aluminum liquid, flushing argon into the vacuum furnace until the pressure in the furnace is 0.1-0.2 MPa, and immersing the nickel-based alloy with the rough surface into the pure aluminum liquid for 10-30 min.

3. The method for preparing a wear-resistant coating on a nickel-base alloy surface according to claim 1, wherein in the step (2), the annealing temperature is 250-400 ℃ and the annealing time is 1-2 h.

4. The method for producing a wear-resistant coating on a nickel-base alloy surface according to claim 1, wherein the thickness of the aluminum-impregnated layer in the step (2) is 500 to 1000. Mu.m.

5. The method for producing a wear-resistant coating on a nickel-base alloy surface according to claim 1, wherein in the step (3), na ₂ WO ₄ 、Na ₂ S、Na ₃ PO ₄ And NaOH in a mass ratio of 6-10: 10-20: 7-12: 1 to 1.5.

6. The method for preparing a wear-resistant coating on a nickel-base alloy surface according to claim 1, wherein in the step (1), the pretreatment specifically comprises: polishing the nickel-based alloy to a mirror surface by adopting sand paper and diamond grinding paste.

7. The method for producing a wear-resistant coating on a nickel-base alloy surface according to claim 1, wherein the etching time in the step (1) is 3 to 10 seconds.

8. The method for preparing the nickel-based alloy surface wear-resistant coating according to claim 1, wherein the method comprises the following steps: the nickel-based alloy is any one of Ni-Cr alloy, ni-Cr-Mo alloy and Ni-Cr-Fe alloy.