WO2017092065A1 - Method for preparing corrosion-resistant coating of marine well drilling platform - Google Patents

Abstract

Disclosed is a method for preparing a corrosion-resistant coating of a marine well drilling platform belonging to the technical field of preparing high-entropy alloy corrosion-resistant coatings. In the method, a double-feeding-port nozzle aerodynamic spraying technology is used to spray an Al-Cr-Fe-Mn-Ni five-component high-entropy alloy powder on a steel structure base body of a marine well drilling platform, and at the same time, a cathode protection metal Zn powder is added so as to obtain a coating having stable components and good corrosion resistance. The double-feeding-port nozzle aerodynamic spraying technology is an effective method for preparing an Al-Cr-Fe-Mn-Ni five-component high-entropy alloy corrosion-resistant coating, and the coating is large, dense, and highly corrosion-resistant, etc.

Description

Preparation method of anti-corrosion coating for marine drilling platform Technical field

[0001] The present invention relates to a method of making a corrosion resistant coating using an offshore drilling platform.

Background technique

The steel structure in offshore drilling platforms has long been in the corrosive environment of marine salt spray, seawater ionization and chemical substances. The traditional anti-corrosion coatings are mostly epoxy coatings, but they have adhesion, seawater corrosion resistance and poor cathodic resistance. Therefore, the offshore platform needs to be repaired or repainted in less than one to two years, not only the maintenance cost. It is huge and affects the use of offshore platforms.

As a multi-component alloy, high-entropy alloy uses the design idea of equimolar mass ratio of more than 4 elements, with high chaos and ultra-high glass forming ability, so it has high strength, high hardness and high wear resistance. Good properties such as high temperature, high temperature resistance and high corrosion resistance. Especially in terms of corrosion resistance, it is much better than steel such as stainless steel. In recent years, high-entropy alloy coating preparation methods include laser coating, electrochemical deposition and magnetron sputtering. These methods have their own advantages and disadvantages. Among them, the electrochemical deposition method is slow in formation and limited by the size of the workpiece, and is suitable for preparing coatings with small thickness. The efficiency of the coating prepared by the magnetron sputtering method is high, but it is limited by equipment and the production cost is high; The coating method is a new technology developed in recent years. It is a high-entropy alloy that melts high-entropy alloy powder onto the surface of the substrate through a higher temperature heat source and a larger degree of aerodynamic force to obtain a certain thickness and desired properties. coating. This process has been relatively extensive, but its use is still limited. Due to the diversity of high-entropy alloy components and the extremely high aerodynamics in the laser heating process, the temperature gradient between the coating and the substrate is too large, resulting in large thermal stress in the coating or over-extension, resulting in The generation of cracks. In addition, more pores are generated during the coating process, and the bonding strength between the substrate and the coating is insufficient during laser sintering. At the same time, the laser-coated structure is a rapidly solidified as-cast structure, and there is segregation at the grain boundary. These factors will ultimately affect the performance of the preparation materials.

In addition, in terms of feeding, the conventional one is a single feed port, and the gas is heated in the front section of the nozzle, which causes the heat to be greatly reduced when it reaches the nozzle, so that the heating effect of the powder is greatly discounted.

Aerodynamic spraying is a type of compressed air that drives metal particles so that they are extremely high at full speed. A new type of spraying technique that strikes a substrate and deposits a coating by plastic deformation through such a violent collision. It has the advantage of eliminating the effects of thermal stress deformation, oxidation, and coarse grain of thermal spray.

However, the use of aerodynamic spraying technology to improve the corrosion resistance of high-entropy alloy coatings on surfaces such as offshore drilling platforms has not been reported.

technical problem

Problem solution

Technical solution

In order to overcome the shortcomings of the prior art mentioned above, the object of the present invention is to provide a novel method for preparing an anti-corrosion coating for an offshore drilling platform, which uses a five-component high-entropy alloy powder of Al-Cr-Fe-Mn-Ni and Zn. The powder of 7:1 powder is used as raw material, and the anti-corrosion coating is prepared on the steel substrate of the offshore drilling platform through the double feed nozzle and aerodynamic spraying technology.

In order to solve the above problems, the present invention adopts the following technical solutions:

The invention discloses a preparation method of an anti-corrosion coating for an offshore drilling platform, which is characterized in that a powder of Al-Cr-Fe-Mn-Ni five-component high-entropy alloy powder and Zn powder mixed with a ratio of 7:1 (mass ratio) is used as a raw material. The feed nozzle and aerodynamic spray technology prepare an anti-corrosion coating on the steel substrate of the offshore drilling platform.

In the process of preparing the corrosion-resistant coating by the aerodynamic spraying technology, the Al-Cr-Fe-Mn-Ni five-component high-entropy alloy powder and the Zn powder are heated from the two inlets respectively through the double feed nozzle. The heater is heated so that the powder temperature reaches 300-400 ° C. The power of the spray is provided by an air compressor with a pressure of 3-5 MPa and a spray distance of 3-5 cm.

The chemical composition ratio of the Al-Cr-Fe-Mn-Ni five-component high-entropy alloy powder is an equimolar ratio of 1:1:1:1:1. It is possible to avoid the formation of intermetallic compounds between the powder elements, which are all brittle substances, which are not good for corrosion protection and hardness improvement. At the same time, the equimolar ratio design idea can make the five elements form a high entropy solid solution, which is very helpful for corrosion protection. Because the high-entropy solid solution is a very stable structure, it is not easy to react with other corrosive liquids.

The chemical composition of the Al-Cr-Fe-Mn-Ni five-component high-entropy alloy powder has a purity requirement of 99.9%.

The preparation process of the Al-Cr-Fe-Mn-Ni five-element high-entropy alloy powder is carried out by mixing the powder into an agate tank, being filled with He gas, and being ball-milled in a mechanical ball mill at a speed of 360 min/s. Ball milling time 100h, the ball to material ratio was 9:1, and after standing for 3 hours, the can was opened in a glove box, and then the mixed powder was placed in a vacuum drying oven and dried at 100 ° C for 1 hour, and stored for use.

Among them, the ball milling time is 100h, and the ball to material ratio is 9:1. The reason for choosing the time and the ball-to-batch ratio is that if the time is too long or the ball-to-batch ratio is not suitable, the powder will not easily form a high-entropy solid solution, and the solid solution is due to the mixing entropy. It is particularly large, so it is not easy to react, and it is very important for corrosion prevention. Therefore, after a large number of experiments, such parameters can be obtained, and this parameter can quickly obtain a high-entropy solid solution structure. This is also confirmed by the subsequent XRD pattern, under which a powder of high entropy solid solution structure is formed.

After standing for 3 hours, the cans were opened in a glove box. The purpose is to obtain a five-component high-entropy alloy powder of Al-Cr-Fe-Mn-Ni which is extremely resistant to corrosion.

The corrosion-resistant coating has a thickness of 10-600 um. The thickness control is determined by the time of spraying.

The base body is sanded with 150# and 600# sandpaper respectively to remove the oil stain and scale, and the metal luster is leaked to increase the interface bonding ability.

The Zn powder has a particle size requirement of less than 20 um and a purity requirement of 99.99%. Its purpose is to provide cathodic protection for Zn to reduce the electrochemical corrosion of seawater.

A spraying device for an anti-corrosion coating of an offshore drilling platform, comprising a compressor and a control system, characterized in that it further comprises a double feed nozzle connected to the compressor, wherein the double feed nozzle is generally in the shape of a truncated cone, There are two inlets 32 on both sides of the tail end of the truncated cone. The inlet port 32 communicates with the mixing chamber 33. The mixing chamber 33 communicates with the discharge port 34 at the top end of the truncated cone. One of the inlets is connected with The storage tank I is connected, and a feed valve II is arranged between the inlet port and the storage tank I, and another inlet port is connected with the storage tank II, and a feed is provided between the inlet port and the storage tank II. The material valve I; the double inlet nozzle is provided with a spiral heater.

The design principle of the invention is as follows:

Based on aerodynamic spraying technology, the high entropy alloy powder is sprayed, the spraying process temperature is lower, the high entropy alloy has a small influence on the high entropy solid solution morphology, reduces the phase transformation in the powder, and reduces the deformation and internal stress of the matrix material. . The high-entropy solid solution has the characteristics of high degree of chaos and many components, which makes the powder extremely stable, and the hardness, anti-friction performance and corrosion resistance of the coating are extremely high.

At the same time, the high-entropy alloy powder and the Zn powder are mixed in a certain ratio, and Zn is used as a cathodic protection metal, which has more excellent resistance to seawater electrolytic corrosion.

Advantageous effects of the invention

Beneficial effect

[0005] The beneficial effects of the present invention are:

1) In order to improve the seawater corrosion resistance of the offshore platform, the A1-Cr-Fe-Mn-Ni five-component high-entropy alloy powder with high stability and corrosion resistance is used, and the cathodic protection metal Zn powder is added at the same time. The corrosion resistance is superior. In the early stage of anti-corrosion, due to the existence of Zn, under the cathodic protection theory, 1/8 is the main force of anti-corrosion, so that the seawater can be corroded first in a certain period of time, and when the Zn powder is corroded, the high entropy Alloy powder has become the focus of anti-corrosion, so due to the existence of high-entropy solid solution, the coating is difficult to react with seawater, so that the anti-corrosion enters the flat corrosion period.

2) The aerodynamic sprayed Al-Cr-Fe-Mn-Ni five-element high-entropy alloy coating process of the present invention has the characteristics of controllable thickness, compactness and strong matrix bonding compared with the existing high-entropy alloy coating preparation process. At the same time, it is easier to maintain the high entropy solid solution morphology of the powder under low temperature, which is very helpful for coating stability, coating strength and wear resistance. The results show that aerodynamic spraying to prepare Al-Cr-Fe-Mn-Ni five-component high-entropy alloy anti-corrosion coating is a very effective method, which fills the blank of anti-corrosion coating preparation at home and abroad.

3) The double feed hole nozzle aerodynamic spraying technology pioneered by the invention is more compact and simpler in equipment than the conventional aerodynamic spraying technology, and is convenient to be applied to various spraying occasions, and the adaptability is greatly improved. In terms of effect, the powder flows into the nozzle more uniformly under the action of siphoning, and the whole nozzle is spirally heated to ensure that the temperature of the mixed powder is substantially constant at 350 ° C, so that the plasticity of the powder is improved, and it is easier to combine with the substrate, and finally the prepared coating is finally made. The layer is more dense and the bonding performance is better.

4) The double feed nozzle of the invention can be combined with different types of powder while heating the screw at the nozzle, which greatly increases the activity of the powder. Conducive to the formation of the coating. Together with the concept of a double nozzle, different powders can be prepared simultaneously onto the surface of the substrate.

Brief description of the drawing

DRAWINGS

Figure 1 is a schematic view of an aerodynamic spraying device for a double inlet nozzle used in the present invention;

2 is a scanning electron micrograph of the anticorrosive coating of the offshore platform of the present invention; the cross-sectional morphology of the coating when the spraying temperature is 300 ° C and the spraying pressure is 4 MPa;

3 is a scanning electron micrograph of the anticorrosive coating of the marine platform of the present invention; the cross-sectional morphology of the coating when the spraying temperature is 350 ° C and the spraying pressure is 4 MPa;

4 is a scanning electron micrograph of the anti-corrosion coating of the offshore platform of the present invention; the cross-sectional morphology of the coating when the spraying temperature is 400 ° C and the spraying pressure is 4 MPa;

Fig. 5 is a scanning electron micrograph of the anticorrosive coating of the offshore platform of the present invention; the cross-sectional morphology of the coating is sprayed at a temperature of 450 ° C and a spray pressure of 4 MPa. It can be seen from the figure that the coating under the parameters (d) is dense and tightly combined, which is the optimal technical parameter.

Fig. 6 is an X-ray diffraction spectrum of the corrosion resistant coating of the offshore platform of the present invention, and the high-entropy alloy structure of the coating is a body-centered cubic structure.

Figure 7 is a schematic view showing the structure of a double feed nozzle.

Figure 8 is a scanning electron micrograph of a prior art coating;

Figure 9 is a scanning electron micrograph of a prior art coating;

Figure 10 is a scanning electron micrograph of a prior art coating.

In the figure: 1-control system, 2- storage tank, 21-reservoir I, 22-reservoir II, 23-feed valve I, 24-feed valve II, 3-double inlet nozzle, 31-heater, 32-inlet, 33-mixing chamber, 34-outlet, 4-compressor.

Invention embodiment

detailed description

The invention will be described in detail below with reference to the accompanying drawings and embodiments.

A spraying device for anticorrosive coating of an offshore drilling platform, comprising a compressor 4 and a control system 1, further comprising a double inlet nozzle 3 communicating with the compressor 1, the double inlet nozzle 3 being generally in the shape of a truncated cone Two inlet ports 32 are provided on both sides of the tail end of the trough, and the inlet port 32 communicates with the mixing chamber 33, and the mixing chamber 33 communicates with the discharge port 34 at the top end of the truncated cone, one of which is fed The port 32 is connected to the storage tank I21, and a feed valve II24 is arranged between the inlet port 32 and the storage tank I21, and another inlet port 32 is connected with the storage barrel II22 at the inlet port 32 and the storage barrel. A feed valve I23 is provided between II22; the double feed nozzle 3 is provided with a spiral heater. 32

As shown in Fig. 1, the Al-Cr-Fe-Mn-Ni five-component high-entropy alloy powder is placed in the storage tank I21 and the Zn powder is placed in the storage tank II22, and the feed valve I23 and the feed valve II24 are adjusted. The Al-Cr-Fe-Mn-Ni five-component high-entropy alloy powder and the Zn powder feed mass ratio are adjusted to 7:1. The compressor 4 is turned on so that the air pressure enters the double feed port nozzle 3, and the double feed nozzle carries the heater 31 for heating the powder.

The double feed nozzle has a truncated cone shape as a whole, and two inlet ports 32 are provided on both sides of the tail end of the truncated cone. The spout 32 communicates with the mixing chamber 33, and the mixing chamber 33 communicates with the discharge port 34 at the top end of the truncated cone.

In the invention, the spraying raw material is a self-made Al-Cr-Fe-Mn-Ni five-component high-entropy alloy powder, and the sprayed substrate is a marine platform steel structure. The specific process parameters are as follows: the chemical composition distribution ratio is an equimolar ratio of 1:1:1:1:1; the purity requirement is 99.9%; the powder is placed in an agate tank for mixing, He gas protection, ball milling in a mechanical ball mill , the speed is 360min/s, the ball milling time is 100h, the ball ratio is 9:1, the ball is allowed to stand for 3 hours, the can is opened in the glove box, and then the mixed powder is placed in a vacuum drying oven and dried at 100 ° C for 1 hour. Store for backup.

In the present invention, the specific parameters of the above spraying device are as follows: the powder heating temperature is 300-400 ° C, the spraying distance is 3-5 cm, and the spraying pressure is 3-5 MPa. Before spraying, the base body is sanded with 150# and 600# sandpaper respectively to remove the oil stain and scale, and the metal luster is leaked to increase the interface bonding ability.

Example 1

The anti-corrosion coating material of the offshore drilling platform is Al-Cr-Fe-Mn-Ni five-component high-entropy alloy powder, and its chemical composition specific gravity is an equimolar ratio; the compressed air is selected as the spraying power, and the above powder and Zn powder are 7:1. The mixing pressure was 4 MPa, the spraying temperature was 300 ° C, and the spraying distance was 3.5 cm. The surface of the steel platform substrate of the offshore platform was sprayed by a dual nozzle feed port aerodynamic device.

Example 2

The anti-corrosion coating material of the offshore drilling platform is Al-Cr-Fe-Mn-Ni five-component high-entropy alloy powder, and its chemical composition specific gravity is an equimolar ratio; the compressed air is selected as the spraying power, and the above powder and Zn powder are 6:1. The mixing pressure was 4 MPa, the spraying temperature was 350 ° C, and the spraying distance was 3.5 cm. The surface of the steel platform substrate of the offshore platform was sprayed by a dual nozzle feed port aerodynamic device.

Example 3

The anti-corrosion coating material of the offshore drilling platform is Al-Cr-Fe-Mn-Ni five-component high-entropy alloy powder, and its chemical composition specific gravity is an equimolar ratio; the compressed air is selected as the spraying power, and the above powder and Zn powder are 7:1. The mixing pressure was 4 MPa, the spraying temperature was 400 ° C, and the spraying distance was 4.5 cm. The surface of the steel platform substrate of the offshore platform was sprayed by a dual nozzle feed port aerodynamic device.

Example 4

The anti-corrosion coating material of the offshore drilling platform is Al-Cr-Fe-Mn-Ni five-component high-entropy alloy powder, and its chemical composition specific gravity is an equimolar ratio; the compressed air is selected as the spraying power, and the above powder and Zn powder are 7:1. The mixing pressure was 4 MPa, the spraying temperature was 450 ° C, and the spraying distance was 4 cm. The surface of the steel platform substrate of the offshore platform was sprayed by a dual nozzle feed port aerodynamic device.

Claims (9)

1. The invention discloses a preparation method of an anti-corrosion coating for an offshore drilling platform, which is characterized in that: the method uses a powder of Al-Cr-Fe-Mn-Ni five-component high-entropy alloy powder and Zn powder mixed with 7:1 as a raw material, through double The feed hole nozzle and aerodynamic spray technology prepare an anticorrosive coating on the steel substrate of the offshore drilling platform.
2. The method for preparing an anti-corrosion coating for an offshore drilling platform according to claim 1, characterized in that: in the process of preparing a corrosion-resistant coating by aerodynamic spraying technology, a double feed nozzle, Al-Cr-Fe-Mn- The Ni five-component high-entropy alloy powder and Zn powder are heated from the two feed ports through the heater, so that the powder temperature reaches 300-400 ° C. The power of the spray is provided by the air compressor, the pressure is 4 Mpa, and the spray distance is 3. -5cm.
3. The method for preparing a corrosion resistant coating for an offshore drilling platform according to claim 1, wherein the Al-Cr-Fe-Mn-Ni five-component high-entropy alloy powder has a chemical composition ratio of equimolar ratio 1 : 1: 1: 1:1.
4. The method for preparing a corrosion resistant coating for an offshore drilling platform according to claim 1, wherein the chemical composition of the Al-Cr-Fe-Mn-Ni five-component high-entropy alloy powder has a purity requirement of 99.9%. .
5. The method for preparing a corrosion resistant coating for an offshore drilling platform according to claim 1, wherein the preparation process of the Al-Cr-Fe-Mn-Ni five-component high-entropy alloy powder is as claimed in claim 3. The powder is placed in an agate tank for mixing, gas-filled, ball milled in a mechanical ball mill, rotating at 360 min/s, ball milling time 100 h, ball-to-batch ratio 9:1, ball milled and allowed to stand for 3 hours, in a glove box The can was opened in a can, and the mixed powder was placed in a vacuum drying oven and dried at 100 ° C for 1 hour, and stored for use.
6. The method of preparing an anti-corrosion coating for an offshore drilling platform according to claim 1, wherein the corrosion-resistant coating has a thickness of 10-600 um.
7. The method for preparing an anti-corrosion coating for an offshore drilling platform according to claim 1, wherein the base body is sanded with 150# and 600 grit sandpaper respectively to remove oil stains and scale, and to leak metallic luster to increase interface bonding. ability.
8. A method of preparing a marine drilling platform corrosion resistant coating according to claim 1 It is: the Zn powder has a particle size requirement of less than 20 um and a purity requirement of 99.99%.
9. A spraying apparatus for an anti-corrosion coating for an offshore drilling platform according to claim 1, comprising a compressor and a control system, further comprising a double inlet nozzle communicating with the compressor, said double inlet The nozzle is generally in the shape of a truncated cone. Two inlet ports 32 are provided on both sides of the tail end of the trough. The inlet port 32 communicates with the mixing chamber 33, and the mixing chamber 33 communicates with the discharge port 34 at the top end of the truncated cone. One of the inlets is connected to the storage tank I, and a feed valve II is arranged between the inlet and the storage tank I, and another inlet is connected to the storage tank II, at the inlet and the storage A feed valve I is provided between the barrels II; the double inlet nozzle is provided with a spiral heater.

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