A corrosion-resistant fastener and its preparation method

Abstract

This invention discloses a corrosion-resistant fastener. It includes a fastener substrate; the surface of the fastener substrate is coated with a corrosion-resistant coating; the corrosion-resistant coating comprises a transition layer, an anti-corrosion layer, and a sealing layer stacked sequentially from the inside out. The corrosion-resistant coating is prepared on the fastener surface using vapor deposition technology and a brushing process. This corrosion-resistant coating, composed of a transition layer, an anti-corrosion layer, and a sealing layer, effectively solves the problems of low hardness, poor adhesion, poor abrasion resistance, and insufficient corrosion resistance of existing fastener surface protective coatings, thereby improving the corrosion resistance of the fastener and extending its service life.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of oil and gas field tools, in particular to a kind of corrosion-resistant fastener and preparation method. BACKGROUND

[0002] Fastener is commonly used tool in oil and gas field, and main material is ordinary carbon steel, high-strength steel, alloy steel etc.In different corrosion environments, steel fastener is poor in corrosion resistance to H2S, CO2, bacteria, water, dissolved oxygen, acid and alkali etc., which can seriously affect the normal use and safety of equipment and device, electronic and electrical and industrial engineering structure.

[0003] At present, the main methods to improve the corrosion resistance of fastener include zinc infiltration, aluminum infiltration, phosphating, cadmium plating, zinc plating, chromate treatment etc.The above methods all have the shortcomings of low hardness, poor bonding force, poor friction resistance and insufficient corrosion resistance, which leads to low service life of fastener in oil and gas field and seriously limits the application of fastener in oil and gas field corrosion medium environment. SUMMARY

[0004] In order to solve the problems in the prior art, the present application provides a kind of corrosion-resistant fastener and preparation method.A corrosion-resistant coating is prepared on the surface of the fastener by gas deposition technology and brushing process.The corrosion-resistant coating is composed of transition layer, corrosion-resistant layer and sealing layer in sequence, thereby effectively solving the problems of low hardness, poor bonding force, poor friction resistance and insufficient corrosion resistance of the surface protective coating of existing fastener, improving the corrosion resistance of fastener and prolonging the service life of fastener.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0006] A kind of corrosion-resistant fastener, comprising a fastener base body;

[0007] The surface of the fastener base body is coated with a corrosion-resistant coating;The corrosion-resistant coating comprises a transition layer, a corrosion-resistant layer and a sealing layer stacked in sequence from inside to outside.

[0008] Preferably, the transition layer is a titanium metal layer, and the thickness of the titanium metal layer is in the range of 1-10 μm.

[0009] Preferably, the corrosion-resistant layer is a metal oxide layer, and the thickness of the metal oxide layer is in the range of 2-8 μm.

[0010] Preferably, the metal oxide layer is composed of nano-crystalline grains, and the grain size of the metal oxide layer is 100-300 nm.

[0011] Preferably, the sealing layer is an epoxy organic compound layer, and the thickness of the epoxy organic compound layer is in the range of 5-10 μm.

[0012] A method for preparing a corrosion-resistant fastener, comprising the following steps,

[0013] Step 1, preparing a transition layer on the surface of the fastener substrate by chemical vapor deposition;

[0014] Step 2, preparing a corrosion-resistant layer on the surface of the transition layer by chemical vapor deposition;

[0015] Step 3, preparing a sealing layer on the surface of the metal oxide layer by spraying.

[0016] Preferably, in Step 1, before preparing the transition layer, the surface of the fastener substrate is cleaned by high-energy plasma under vacuum conditions.

[0017] Preferably, in Step 1, the transition layer is prepared by chemical vapor deposition of a titanium metal layer, the deposition temperature of the titanium metal layer is 600-650℃, and the deposition time is 4-10h; the titanium metal layer is a titanium carbide layer, a titanium nitride layer, and / or a titanium carbonitride layer.

[0018] Preferably, in Step 2, the corrosion-resistant layer is prepared by chemical vapor deposition of a metal oxide layer, the deposition temperature of the metal oxide layer is 1000-1100℃, and the deposition time is 2-5h; the metal oxide layer is an aluminum oxide layer, which is composed of micrometer crystals with a size of 1-3μm.

[0019] Preferably, in Step 3, the sealing layer is prepared by spraying an epoxy-based organic compound layer, and the thickness of the sealing layer is 5-10μm.

[0020] Compared with the prior art, the present application has the following beneficial technical effects:

[0021] The corrosion-resistant fastener provided by the present application is coated with a corrosion-resistant coating layer composed of a transition layer, a corrosion-resistant layer, and a sealing layer: first, the transition layer and the corrosion-resistant layer are prepared on the surface of the fastener substrate in sequence by a vapor deposition process, and then the sealing layer is prepared on the surface of the corrosion-resistant layer by brushing, and finally the corrosion-resistant coating layer is obtained on the surface of the fastener. The transition layer can be used to alleviate the mismatch of the thermal expansion coefficients of the corrosion-resistant layer and the fastener substrate, reduce the interfacial stress, and improve the bonding strength of the corrosion-resistant layer and the fastener substrate; the corrosion-resistant layer is a metal oxide layer with a micrometer crystal structure, which is mainly used to provide corrosion resistance, wear resistance, and electrochemical insulation; the sealing layer is an epoxy-based organic compound layer, which is mainly used to seal the micropores on the surface of the corrosion-resistant layer, and the sealing layer itself also has good corrosion resistance, thereby further enhancing the corrosion resistance of the fastener. The present application can effectively solve the problems of low hardness, poor bonding strength, poor friction resistance, and insufficient corrosion resistance of the existing metal fastener surface protection technology, and significantly improve the corrosion resistance and service life of the fastener surface. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 A schematic diagram of the surface corrosion-resistant coating structure of the corrosion-resistant fastener.

[0023] Figure 2 A morphology test diagram of the corrosion-resistant coating of the corrosion-resistant fastener in Example 1 of the present application.

[0024] Figure 3 A Vickers hardness test diagram of the corrosion-resistant fastener in Example 1 of the present application.

[0025] Figure 4 A bonding force performance test diagram of the corrosion-resistant fastener in Example 1 of the present application.

[0026] Figure 5 A friction resistance performance test diagram of the corrosion-resistant fastener in Example 1 of the present application.

[0027] Figure 6 A corrosion resistance performance test diagram of the corrosion-resistant fastener in Example 1 of the present application.

[0028] In the drawings: 1 is the fastener base body; 2 is the transition layer; 3 is the corrosion-resistant layer; 4 is the sealing layer. DETAILED DESCRIPTION

[0029] The present application will be further described in conjunction with specific examples, which are an explanation of the present application rather than a limitation.

[0030] The corrosion-resistant fastener of the present application comprises a fastener base body 1 and a corrosion-resistant coating formed on the surface of the fastener base body 1.

[0031] The corrosion-resistant coating is composed of a transition layer 2, a corrosion-resistant layer 3 plated on the surface of the transition layer 2, and a sealing layer 4 plated on the surface of the corrosion-resistant layer 3, in sequence, wherein the transition layer 2 is located between the surface of the fastener base body 1 and the corrosion-resistant layer 3, and the sealing layer 4 is located on the outer surface of the corrosion-resistant layer 3.

[0032] The preparation method of the corrosion-resistant fastener of the present application is as follows:

[0033] S1, under vacuum conditions, the surface of the fastener is cleaned by high-energy plasma. The high-energy plasma is Ar gas plasma, and the cleaning time is 15-45 min.

[0034] S2, the transition layer 2 is prepared on the surface of the fastener by chemical vapor deposition. The transition layer 2 is a titanium metal layer, and the thickness of the titanium metal layer is 1-10 μm. The deposition temperature of the titanium metal layer is 600-650 ℃, and the deposition time is 4-10 h. The titanium metal layer is a titanium carbide layer, a titanium nitride layer, and / or a titanium carbonitride layer.

[0035] S3, a corrosion resistant layer 3 is prepared on the surface of the titanium metal layer by chemical vapor deposition. The corrosion resistant layer 3 is a metal oxide layer, and the thickness of the metal oxide layer is 2-8 μm. The deposition temperature of the metal oxide layer is 1000-1100 °C, and the deposition time is 2-5 h. The metal oxide layer is an aluminum oxide layer. The aluminum oxide layer is composed of micron crystals, and the size of the micron crystals is 1-3 μm.

[0036] S4, a sealing layer 4 is prepared on the surface of the metal oxide layer by spraying, and the sealing layer 4 is an epoxy organic compound layer, and the thickness of the sealing layer is 5-10 μm.

[0037] Example 1

[0038] A corrosion resistant fastener, the corrosion resistant fastener comprising a fastener base 1; the fastener in this embodiment is a bolt, and the surface of the fastener base 1 is coated with a corrosion resistant coating. The corrosion resistant coating is composed of a transition layer 2, a corrosion resistant layer 3 coated on the surface of the transition layer 2, and a sealing layer 4 coated on the surface of the corrosion resistant layer 3, wherein the transition layer 2 is located between the surface of the fastener base 1 and the corrosion resistant layer 3, and the sealing layer 4 is located on the outer surface of the corrosion resistant layer 3.

[0039] The corrosion resistant coating is prepared by the following steps:

[0040] S1, the fastener is placed in a vacuum chamber, and the vacuum in the vacuum chamber is pumped to 10 -4 Pa by using a vacuum pump set; then a certain amount of argon gas is introduced, and a high-frequency pulse voltage is loaded to form a high-energy argon plasma to clean the surface of the fastener, and the cleaning time is 35 min.

[0041] S2, after cleaning, a certain amount of N2 and TiCl4 is introduced, and a titanium nitride transition layer is prepared on the surface of the fastener by chemical vapor deposition. The deposition temperature is 650 °C, and the deposition time is 10 h.

[0042] S3, after the preparation of the transition layer is completed, a corrosion resistant layer is prepared on the surface of the transition layer by chemical vapor deposition. The corrosion resistant layer is an aluminum oxide coating, and the deposition temperature of the corrosion resistant layer is 1050 °C, and the deposition time is 5 h.

[0043] S4, after the preparation of the corrosion resistant layer is completed, a sealing layer is prepared on the surface of the corrosion resistant layer by spraying. The sealing layer is a polyimide layer, and the spraying thickness of the polyimide layer is 10 μm.

[0044] After the preparation of the sealing layer on the surface of the fastener is completed, a corrosion resistant fastener is finally obtained.

[0045] Test results

[0046] Figure 2 The surface morphology test diagram of the aluminum oxide corrosion resistant layer coated on the surface of the corrosion resistant fastener of the present application. Figure 2The data shows that the alumina grain size in the corrosion-resistant fastener surface alumina anti-corrosion layer obtained in Example 1 is micrometer-sized, with a grain size of 2μm. The grains are tightly bonded, and the coating has high density.

[0047] Figure 3 This is a hardness test diagram for a corrosion-resistant fastener according to the present invention. Figure 3 The data shows that the hardness of the corrosion-resistant fastener obtained in Example 1 is 1600 HV.

[0048] Figure 4 This is a test diagram of the adhesion of a corrosion-resistant coating on the surface of a corrosion-resistant fastener according to the present invention. Figure 4 The figure shows that the adhesion of the corrosion-resistant coating on the surface of the corrosion-resistant fastener obtained in Example 1 is 65N.

[0049] Figure 5 This is a test diagram showing the friction resistance performance of a corrosion-resistant coating on the surface of a corrosion-resistant fastener according to the present invention. Figure 5 The data shows that the coefficient of friction of the corrosion-resistant coating on the surface of the corrosion-resistant fastener obtained in Example 1 is 0.2.

[0050] Figure 6 This is a test diagram of the corrosion resistance performance of a corrosion-resistant fastener according to the present invention. Figure 6 The data shows that the average corrosion rate of the corrosion-resistant fasteners obtained in Example 1 was 0.0021 mm / a.

[0051] A corrosion-resistant fastener prepared according to the above method has a hardness of 1200HV-1600HV, a coefficient of friction of 0.2-0.5, an adhesion force of 40-65N, and an average corrosion rate of 0.0021-0.0085mm / a on the surface of the fastener substrate 1.

[0052] Example 2

[0053] The method is the same as in Example 1, except that in step S1, the high-energy plasma cleaning time is 10 minutes.

[0054] The results showed that the grain size of the prepared alumina coating was 220 nm; the hardness of the corrosion-resistant coating on the surface of the prepared corrosion-resistant fastener was 1510 HV; the coefficient of friction was 0.3; the adhesion was 55 N; and the average corrosion rate was 0.0045 mm / a.

[0055] Example 3

[0056] The method is the same as in Example 1, except that in step S2, the thickness of the transition layer 2 is 1 μm.

[0057] The results show that the grain size of the prepared aluminium oxide corrosion protection layer is 140 nm; the hardness of the prepared corrosion resistant fastener surface corrosion resistant coating is 1200 HV; the friction coefficient is 0.5; the binding force is 40 N; and the average corrosion rate is 0.0085 mm / a.

[0058] Example 4

[0059] The method is the same as in Example 1, except that in step S2, the thickness of the transition layer 2 is 5 μm.

[0060] The results show that the grain size of the prepared aluminium oxide corrosion protection layer is 220 nm; the hardness of the prepared corrosion resistant fastener surface corrosion resistant coating is 1510 HV; the friction coefficient is 0.3; the binding force is 58 N; and the average corrosion rate is 0.0036 mm / a.

[0061] Example 5

[0062] The method is the same as in Example 1, except that in step S3, the thickness of the corrosion protection layer 3 is 1 μm.

[0063] The results show that the grain size of the prepared aluminium oxide corrosion protection layer is 140 nm; the hardness of the prepared corrosion resistant fastener surface corrosion resistant coating is 1400 HV; the friction coefficient is 0.4; the binding force is 48 N; and the average corrosion rate is 0.0072 mm / a.

[0064] Example 6

[0065] The method is the same as in Example 1, except that in step S3, the thickness of the corrosion protection layer 3 is 4 μm.

[0066] The results show that the grain size of the prepared aluminium oxide corrosion protection layer is 220 nm; the hardness of the prepared corrosion resistant fastener surface corrosion resistant coating is 1550 HV; the friction coefficient is 0.3; the binding force is 62 N; and the average corrosion rate is 0.0028 mm / a.

[0067] Example 7

[0068] The method is the same as in Example 1, except that in step S3, the thickness of the sealing layer 4 is 5 μm.

[0069] The results show that the grain size of the prepared aluminium oxide corrosion protection layer is 200 nm; the hardness of the prepared corrosion resistant fastener surface corrosion resistant coating is 1570 HV; the friction coefficient is 0.3; the binding force is 62 N; and the average corrosion rate is 0.0027 mm / a.

[0070] Example 8

[0071] The method is the same as in Example 1, except that in step S3, the thickness of the sealing layer 4 is 7 μm.

[0072] The results show that the grain size of the prepared aluminum oxide anticorrosion layer is 210 nm; the hardness of the prepared corrosion-resistant surface coating of the fastener is 1575HV; the friction coefficient is 0.3; the bonding force is 63N; and the average corrosion rate is 0.0025mm / a.

[0073] The corrosion-resistant fastener of the present application is coated with a corrosion-resistant coating on the surface of the fastener. The corrosion-resistant coating has a three-layer structure of a transition layer, an anticorrosion layer and a sealing layer. The transition layer is a titanium metal layer; the anticorrosion layer is a metal oxide layer; and the sealing layer is an epoxy organic compound layer. The anticorrosion layer has a micron crystal structure. The corrosion-resistant layer has the characteristics of high hardness, strong bonding, resistance to friction and wear, corrosion resistance, etc. The present application effectively solves the problems of easy wear and corrosion of existing fasteners in oil and gas field corrosion conditions, and significantly improves the wear resistance and corrosion resistance of the surface of the fastener.

[0074] First, a transition layer and an anticorrosion layer are prepared on the surface of the fastener substrate in sequence by a gas deposition process, and a sealing layer is prepared on the surface of the anticorrosion layer by brushing, to finally obtain a corrosion-resistant coating on the surface of the fastener. The transition layer is a titanium metal layer, which is mainly used to relieve the mismatch of the thermal expansion coefficients of the anticorrosion layer and the fastener substrate, reduce the interfacial stress, and improve the bonding strength of the anticorrosion layer and the fastener substrate; the anticorrosion layer is a metal oxide layer, which has a micron crystal structure and is mainly used to provide corrosion resistance, wear resistance, and electrochemical insulation; and the sealing layer is an epoxy organic compound layer, which is mainly used to seal the micropores on the surface of the anticorrosion layer, and the sealing layer itself also has good corrosion resistance, thereby further enhancing the corrosion resistance of the fastener. The present application can effectively solve the problems of low hardness, poor bonding, poor friction resistance, and insufficient corrosion resistance of the existing surface protection technology of metal fasteners, and significantly improve the corrosion resistance and service life of the surface of the fastener.

[0075] It should be understood that the protection scope of the present application is not limited to the specific statements and examples in the present application, and all other various specific modifications and combinations made by the relevant personnel in the art without departing from the essence of the present application based on the disclosed technical features and functional compositions of the present application are within the protection scope of the present application. In addition, within the scope of the present application, the above technical features of the present application and the technical features specifically described in the following (such as examples) can be combined with each other to form new or preferred technical solutions, which are also within the protection scope of the present application. Due to the limited space, they will not be listed one by one here.

Claims

1. A method of making a corrosion resistant fastener, characterized by, The fastener base (1) is coated with a corrosion-resistant coating on the surface. The fastener base (1) is coated with a corrosion-resistant coating on the surface. The method comprises the following steps, Step 1: a transition layer (2) is prepared on the surface of the fastener base (1) by chemical vapor deposition; the transition layer (2) is formed by preparing a titanium metal layer by chemical vapor deposition, and the deposition temperature of the titanium metal layer is 600-650 DEG C, and the deposition time is 4-10 h; Step 2: a corrosion-resistant layer (3) is prepared on the surface of the transition layer (2) by chemical vapor deposition; the corrosion-resistant layer (3) is formed by preparing a metal oxide layer by chemical vapor deposition, and the deposition temperature of the metal oxide layer is 1000-1100 DEG C, and the deposition time is 2-5 h; the metal oxide layer is an aluminum oxide layer, and the aluminum oxide layer is composed of micrometer crystals, and the size of the micrometer crystals is 1-3 μm; Step 3: a sealing layer (4) is prepared on the surface of the metal oxide layer by spraying; the sealing layer (4) is formed by preparing an epoxy organic compound layer by spraying, and the thickness of the sealing layer (4) is 5-10 μm.

2. The method of making a corrosion-resistant fastener according to claim 1, wherein, The transition layer (2) is a titanium metal layer, and the thickness of the titanium metal layer ranges from 1 to 10 μm.

3. The method of making a corrosion-resistant fastener according to claim 1, wherein, The corrosion-resistant layer (3) is a metal oxide layer, and the thickness of the metal oxide layer ranges from 2 to 8 μm.

4. The method of making a corrosion-resistant fastener according to claim 3, wherein, The metal oxide layer is composed of nanocrystalline grains, and the grain size of the metal oxide layer is 100-300 nm.

5. The method of making a corrosion-resistant fastener according to claim 1, wherein The sealing layer (4) is an epoxy organic compound layer, and the thickness of the epoxy organic compound layer ranges from 5 to 10 μm.

6. The method of making a corrosion-resistant fastener according to claim 1, wherein, In step 1, before the transition layer (2) is prepared, the surface of the fastener base (1) is cleaned by high-energy plasma under vacuum conditions.

7. The method of making a corrosion-resistant fastener according to claim 1, wherein In step 1, the titanium metal layer is a titanium carbide layer, a titanium nitride layer and / or a titanium carbonitride layer.

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