Titanium-based corrosion-resistant material as well as preparation method and application thereof

Abstract

The invention provides a titanium-based corrosion-resistant material which comprises a titanium base material and a corrosion-resistant layer arranged on the surface of the titanium base material, and the corrosion-resistant layer comprises a titanium-molybdenum alloy layer and a transition layer arranged between the titanium-molybdenum alloy layer and the titanium base material; the content of Ti in the titanium base material is not less than 90wt%; the average grain size D1 of the titanium base material is greater than the average grain size D2 of the transition layer, and the average grain size D3 of the titanium-molybdenum alloy layer is greater than the average grain size D2 of the transition layer; and the Mo content A1 in the titanium base material is greater than the Mo content A2 in the transition layer and is less than the Mo content A3 in the titanium-molybdenum alloy layer. A special transition layer is formed between a titanium substrate and a titanium-molybdenum alloy layer, and the average grain size and Mo content of the transition layer are regulated and controlled, so that the average grain size of the transition layer is between coarse grains of the titanium substrate and fine grains of the titanium-molybdenum alloy layer, and the Mo content of the transition layer is between the coarse grains of the titanium substrate and the fine grains of the titanium-molybdenum alloy layer. The corrosion resistance of the surface of the titanium base material can be further improved on the premise that the machining forming performance of the titanium base material is guaranteed.

Description

Technical Field

[0001] The present invention relates to the technical field of corrosion-resistant materials, and in particular to a titanium-based corrosion-resistant material and a preparation method and application thereof. Background Art

[0002] Titanium materials are widely used in petrochemicals, medical devices and other fields due to their advantages such as low density, high specific strength and good biocompatibility.

[0003] Pure titanium has a certain degree of corrosion resistance due to its tendency to form an oxide film on its surface. However, due to its high chemical activity, pure titanium's corrosion resistance is significantly reduced in reducing acid solutions, such as strong acids, high fluorine and chlorine content, and ammonium magnesium sulfate solutions. Furthermore, in oxidizing media, such as dry silkworm gas and fuming nitric acid, the oxidation reaction on the titanium surface is too intense due to the destruction of the original oxide film, posing a risk of explosion and fire.

[0004] In the related art, there is a method of improving the corrosion resistance of titanium materials by alloying. However, although the addition of alloying elements improves the corrosion resistance to a certain extent, it is difficult to further improve the corrosion resistance, and alloying has an adverse effect on the processing performance of the material. Summary of the Invention

[0005] The main purpose of the present invention is to provide a titanium-based corrosion-resistant material and its preparation method and application, so as to improve the problem that it is difficult to balance the processing performance and corrosion resistance of titanium materials and it is difficult to further improve the corrosion resistance.

[0006] To achieve the above objectives, the first aspect of the present invention provides a titanium-based corrosion-resistant material, comprising a titanium substrate and a corrosion-resistant layer disposed on the surface of the titanium substrate, wherein the corrosion-resistant layer comprises a titanium-molybdenum alloy layer and a transition layer disposed between the titanium-molybdenum alloy layer and the titanium substrate;

[0007] The Ti content in the titanium substrate is not less than 90wt%;

[0008] The average grain size of the titanium substrate is D1, the average grain size of the transition layer is D2, and the average grain size of the titanium-molybdenum alloy layer is D3, wherein D1>D2>D3;

[0009] The Mo content in the titanium substrate is A1, the Mo content in the transition layer is A2, and the Mo content in the titanium-molybdenum alloy layer is A3, wherein A1<A2<A3.

[0010] By forming a transition layer and a titanium-molybdenum alloy layer on the surface of the titanium substrate, and regulating the average grain size and Mo content of the transition layer, the average grain size of the transition layer is between the coarse grains of the titanium substrate and the fine grains of the titanium-molybdenum alloy layer, and the Mo content of the transition layer is between the titanium substrate and the titanium-molybdenum alloy layer, the corrosion resistance of the titanium substrate surface can be significantly improved while ensuring the processing and forming performance of the titanium substrate.

[0011] In some embodiments, the thickness of the transition layer is not less than 5 μm;

[0012] Optionally, the thickness of the transition layer is not less than 10 μm;

[0013] Optionally, the thickness of the transition layer is not less than 20 μm;

[0014] Optionally, the thickness of the transition layer is 20-1000 μm;

[0015] Optionally, the average grain size D2 of the transition layer is 5-100 μm.

[0016] In some embodiments, the Mo content A3 in the titanium-molybdenum alloy layer is not less than 25 wt %;

[0017] Optionally, the titanium-molybdenum alloy layer has a Ti content of 65-70 wt% and a Mo content A3 of 30-35 wt%;

[0018] Optionally, the titanium-molybdenum alloy layer has a Ti content of 67-69 wt % and a Mo content A3 of 31-33 wt %;

[0019] Optionally, the average grain size D3 of the titanium-molybdenum alloy layer is 0.5-10 μm.

[0020] In some embodiments, the titanium substrate has a Ti content of not less than 95 wt %;

[0021] Optionally, the Ti content in the titanium substrate is not less than 99 wt %;

[0022] Optionally, the average grain size D1 of the titanium substrate is 25-200 μm.

[0023] A second aspect of the present invention provides a method for preparing a titanium-based corrosion-resistant material, comprising the following steps:

[0024] Provide Ti-Mo alloy powder;

[0025] A titanium substrate is brought into contact with the Ti-Mo alloy powder and subjected to a cladding treatment to sequentially form a transition layer and a titanium-molybdenum alloy layer on the surface of the titanium substrate.

[0026] In some embodiments, the particle size D50 of the Ti-Mo alloy powder is 50-60 μm.

[0027] In some embodiments, the Ti—Mo alloy powder contains Mo at least 25 wt %.

[0028] In some embodiments, the conditions of the cladding process are controlled so that the thickness of the transition layer is greater than 5 μm.

[0029] In some embodiments, the cladding process uses a laser cladding method;

[0030] Optionally, the laser cladding conditions meet one or more of the following conditions:

[0031] A: Laser power is 1500-2000W;

[0032] B: Laser power is 1750-1850W;

[0033] C: Feed speed is 15-21cm / min;

[0034] D: Feed speed is 18-20cm / min.

[0035] A third aspect of the present invention provides an application of the aforementioned titanium-based corrosion-resistant material or the titanium-based corrosion-resistant material prepared by the aforementioned method in petrochemical industry or medical equipment.

[0036] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present application. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0038] Figure 1The cross-sectional SEM and EDS analysis diagrams of the titanium-based corrosion-resistant materials obtained in Examples 1, 2, and 3 of the present invention are shown. (a1), (b1), and (c1) are the cross-sectional SEM diagram, Ti element EDS distribution diagram, and Mo element EDS distribution diagram of the titanium-based corrosion-resistant material in Example 2 of the present invention, respectively; (a2), (b2), and (c2) are the cross-sectional SEM diagram, Ti element EDS distribution diagram, and Mo element EDS distribution diagram of the titanium-based corrosion-resistant material in Example 1 of the present invention; (a3), (b3), and (c3) are the cross-sectional SEM diagram, Ti element EDS distribution diagram, and Mo element EDS distribution diagram of the titanium-based corrosion-resistant material in Example 3 of the present invention.

[0039] Figure 2 The following are SEM images of the titanium-based corrosion-resistant material in Example 1 of the present invention before and after corrosion. (a) is an SEM image of the titanium-based corrosion-resistant material in Example 1 of the present invention before corrosion, and (b) is an SEM image of the titanium-based corrosion-resistant material in Example 1 of the present invention after corrosion.

[0040] Figure 3 The SEM images of the titanium substrate before and after corrosion in Comparative Example 1 of the present invention are shown in FIG. (a) is a SEM image of the titanium substrate before corrosion in Comparative Example 1 of the present invention, and (b) is a SEM image of the titanium substrate after corrosion in Comparative Example 1 of the present invention.

[0041] Figure 4 The following are SEM images and EDS images of the cross-section of the titanium-based corrosion-resistant material in Example 1 of the present invention after acid corrosion treatment. Among them, (a) is an SEM image of the cross-section of the titanium-based corrosion-resistant material in Example 1 of the present invention after acid corrosion treatment, and (b) is an EDS image of the cross-section of the titanium-based corrosion-resistant material in Example 1 of the present invention after acid corrosion treatment.

[0042] Figure 5 This is an EBSD image of the cross section of the titanium-based corrosion-resistant material in Example 1 of the present invention after acid corrosion treatment.

[0043] The realization of the objectives, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0044] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0045] In addition, in the present invention, descriptions such as "first" and "second" are for descriptive purposes only and should not be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. Moreover, the technical solutions between the various embodiments of the present invention can be combined with each other, but this must be based on the fact that they can be implemented by ordinary technicians in this field. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0046] In the present invention, the average grain size refers to the arithmetic average of the grains in the material, which can be measured by electron backscatter diffraction (EBSD) method.

[0047] In the present invention, unless otherwise specified, the content of an element is expressed in percentage by mass.

[0048] As described above, an embodiment of the present invention provides a titanium-based corrosion-resistant material, comprising a titanium substrate and a corrosion-resistant layer disposed on the surface of the titanium substrate, wherein the corrosion-resistant layer comprises a titanium-molybdenum alloy layer and a transition layer disposed between the titanium-molybdenum alloy layer and the titanium substrate;

[0049] The Ti content in the titanium substrate is not less than 90wt%;

[0050] The average grain size of the titanium substrate is D1, the average grain size of the transition layer is D2, and the average grain size of the titanium-molybdenum alloy layer is D3, wherein D1>D2>D3;

[0051] The Mo content in the titanium substrate is A1, the Mo content in the transition layer is A2, and the Mo content in the titanium-molybdenum alloy layer is A3, wherein A1<A2<A3.

[0052] In the embodiment of the present invention, a special transition layer is formed between the titanium substrate and the titanium-molybdenum alloy layer, and the average grain size and Mo content of the transition layer are regulated so that the average grain size of the transition layer is between the coarse grains of the titanium substrate and the fine grains of the titanium-molybdenum alloy layer, and the Mo content of the transition layer is between the titanium substrate and the titanium-molybdenum alloy layer. This can further improve the corrosion resistance of the titanium substrate surface while ensuring the processing and forming performance of the titanium substrate.

[0053] Specifically, in the titanium-molybdenum alloy layer, the addition of a high content of Mo causes part of the α phase to transform into the more chemically stable and corrosion-resistant β phase, while also refining the grains to form an α+β phase structure, resulting in better corrosion resistance. However, while grain refinement has a certain effect on inhibiting corrosion, the high degree of alloying makes it easy for second phase precipitation and element segregation to occur at the grain boundaries, so the fine-grained layer of the titanium-molybdenum alloy still faces a certain corrosion risk.

[0054] In the present invention, a transition layer is formed between the fine-grained titanium-molybdenum alloy layer and the coarse-grained titanium substrate. The average grain size of the transition layer is between the coarse-grained titanium substrate and the fine-grained titanium-molybdenum alloy layer, that is, its average grain size is finer than that of the titanium substrate. At the same time, the Mo content introduced into the transition layer is lower than that of the titanium-molybdenum alloy layer, which can cause phase transformation and form an α+β phase structure. However, since only a small amount of Mo element enters the transition layer in the form of diffusion, the degree of alloying is not high, and the risk of second phase precipitation and element segregation is small, the transition layer can have better corrosion resistance than the titanium-molybdenum alloy layer, thereby further improving the corrosion resistance of the titanium substrate corrosion-resistant material.

[0055] In some embodiments, the thickness of the transition layer is not less than 5 μm; optionally, the thickness of the transition layer is not less than 10 μm; further optionally, the thickness of the transition layer is not less than 20 μm; further optionally, the thickness of the transition layer is 20-1000 μm. As previously mentioned, compared with the titanium substrate and the titanium-molybdenum alloy layer, the transition layer has better corrosion resistance. The thicker the transition layer formed on the surface of the titanium substrate, the further improved the corrosion resistance. To balance the corrosion resistance and processing properties of the titanium-based material, the thickness of the transition layer can be, for example, 20 μm, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, 1000 μm, 100-900 μm, 200-600 μm, 300-60 μm, or any value or range consisting of any values between 20-1000 μm.

[0056] In some embodiments, the Mo content A2 in the transition layer satisfies the following: 0 ≤ A2 ≤ 35 wt%; further optionally, 0 ≤ A2 ≤ 32 wt%; further optionally, 0 ≤ A2 ≤ 25 wt%. It should be noted that the Mo content in the transition layer may be non-uniform. In some embodiments, the transition layer is formed during a processing process, for example, during a laser cladding process, where Mo in the transition layer diffuses from the titanium-molybdenum alloy layer to the surface of the titanium substrate. Consequently, the Mo content varies in different diffusion layers, generally with higher Mo content nearer the titanium-molybdenum alloy layer and lower Mo content nearer the titanium substrate.

[0057] In some embodiments, the transition layer has an average grain size D2 of 5-100 μm. For example, D2 is 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 5-10 μm, 5-20 μm, 5-30 μm, 10-30 μm, 20-30 μm, 5-50 μm, 10-50 μm, 20-50 μm, 5-90 μm, 50-90 μm, 5-100 μm, or any value or range consisting of any value therebetween.

[0058] In some embodiments, the Mo content A3 in the titanium-molybdenum alloy layer is not less than 25 wt %;

[0059] Optionally, the Ti content in the titanium-molybdenum alloy layer is 65-70wt%, and the Mo content A3 is 30-35wt%; the Ti content in the titanium-molybdenum alloy layer can be, for example, 65wt%, 66wt%, 67wt%, 68wt%, 69wt%, 70wt% or any value between 65-70wt% or an interval consisting of any values, and the Mo content A3 in the titanium-molybdenum alloy layer can be, for example, 30wt%, 31wt%, 32wt%, 33wt%, 34wt%, 35wt% or any value between 30-35wt% or an interval consisting of any values.

[0060] Further optionally, the Ti content in the titanium-molybdenum alloy layer is 67-69wt%, and the Mo content A3 is 31-33wt%.

[0061] The appropriate Mo content is beneficial to improving the corrosion resistance of the titanium-molybdenum alloy layer, and at the same time facilitates the formation of a transition layer with better corrosion resistance through a simple processing method.

[0062] Further optionally, the average grain size D3 of the titanium-molybdenum alloy layer is 0.5-10 μm. Exemplarily, D3 is 0.5 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 0.5-1 μm, 0.5-2 μm, 0.5-3 μm, 1-3 μm, 2-3 μm, 0.5-5 μm, 1-5 μm, 2-5 μm, 5-9 μm, or any value or interval consisting of any values between 0.5 and 10 μm. The average grain size D3 of the titanium-molybdenum alloy layer is related to the alloy composition and processing technology. A higher Mo content and a lower processing temperature are conducive to forming a titanium-molybdenum alloy layer with finer grains. A suitable average grain size D3 is conducive to ensuring corrosion resistance while having good hardness and wear resistance.

[0063] In some embodiments, the titanium substrate contains no less than 95 wt% Ti; further optionally, the titanium substrate contains no less than 99 wt%. A high Ti content in the titanium substrate facilitates better processing properties. It is understood that when the titanium substrate contains no less than 95 wt%, the Mo content (A1) in the titanium substrate is less than 5 wt%; when the titanium substrate contains no less than 99 wt%, the Mo content (A1) in the titanium substrate is less than 1 wt%; and when the titanium substrate is pure titanium, A1 is 0 wt% or close to 0 wt%.

[0064] Further optionally, the average grain size D1 of the titanium substrate is 25-200 μm. Exemplarily, D1 is 25 μm, 35 μm, 45 μm, 55 μm, 65 μm, 75 μm, 85 μm, 100 μm, 120 μm, 140 μm, 180 μm, 200 μm, 25-35 μm, 25-45 μm, 25-55 μm, 25-65 μm, 35-45 μm, 35-55 μm, 65-200 μm, or any value or range consisting of any values between 25-200 μm. The average grain size of the titanium substrate is affected by the processing history of the titanium substrate. Different processing histories of titanium substrates result in different grain sizes of the titanium substrate. A reasonable titanium substrate grain size is conducive to making the titanium substrate have better processing performance.

[0065] As mentioned above, an embodiment of the present invention further provides a method for preparing a titanium-based corrosion-resistant material, comprising the following steps:

[0066] Provide Ti-Mo alloy powder;

[0067] A titanium substrate is brought into contact with the Ti-Mo alloy powder and subjected to a cladding treatment to sequentially form a transition layer and a titanium-molybdenum alloy layer on the surface of the titanium substrate.

[0068] In the embodiment of the present invention, a Ti-Mo alloy is clad on the surface of a titanium substrate. Through the cladding heat, not only does the Mo element diffuse into the titanium substrate to obtain a transition layer, causing a phase transformation and forming an α+β phase structure, but the cladding treatment also makes the alloying degree of the transition layer low, with less segregation at the grain boundaries in the transition layer, and the average grain size and partial phase structure of the transition layer transformed, giving the transition layer better corrosion resistance.

[0069] In some embodiments, the method further comprises: pre-treating the titanium substrate before performing the cladding process. The pre-treatment can improve the surface quality of the titanium substrate and facilitate the formation of a stable transition layer on the surface of the titanium substrate.

[0070] In some embodiments, the pre-processing comprises:

[0071] Grinding treatment: The titanium substrate is subjected to coarse grinding and fine grinding in sequence;

[0072] Polishing: The ground titanium substrate is brought into contact with the polishing liquid.

[0073] In some embodiments, the rough grinding includes using 300-500 grit sandpaper to improve the surface smoothness of the titanium substrate.

[0074] In some embodiments, the fine grinding includes using 1000-1200 grit sandpaper to achieve a high degree of finish on the surface of the titanium substrate.

[0075] In order to further obtain a titanium substrate with higher surface quality and remove the oxide layer, scratches and burrs on the surface of the titanium substrate, in some embodiments, the polishing process includes:

[0076] First polishing treatment: contacting the ground titanium substrate with a first polishing liquid;

[0077] Second polishing treatment: contacting the titanium substrate after the first polishing treatment with a second polishing liquid.

[0078] It should be noted that the embodiments of the present invention have no special requirements on the polishing method and process parameters, and the methods and parameters known to those skilled in the art can be used, which will not be elaborated herein.

[0079] Optionally, the first polishing liquid is a diamond suspension, and the particle size D50 of diamonds in the diamond suspension is 3-8 μm.

[0080] Optionally, the second polishing liquid is a silica suspension, and the particle size D50 of the silica in the silica suspension is 0.1-0.5 μm.

[0081] In some embodiments, the particle size D50 of the Ti-Mo alloy powder is 50-60 μm. The particle size D50 of the Ti-Mo alloy powder can be, for example, 50 μm, 51 μm, 52 μm, 53 μm, 54 μm, 55 μm, 56 μm, 57 μm, 58 μm, 59 μm, 60 μm, or any value or range between 50-60 μm.

[0082] In some embodiments, the Ti-Mo alloy powder contains no less than 25 wt %. Optionally, the titanium-molybdenum alloy layer contains 65-70 wt % of Ti and 30-35 wt % of Mo. Further, the titanium-molybdenum alloy layer contains 67-69 wt % of Ti and 31-33 wt % of Mo.

[0083] In some embodiments, the conditions of the cladding process are controlled so that the thickness of the transition layer is greater than 5 μm; alternatively, the conditions of the cladding process are controlled so that the thickness of the transition layer is 20-1000 μm.

[0084] In some embodiments, the cladding process uses a laser cladding method.

[0085] Optionally, the laser cladding conditions meet one or more of the following conditions:

[0086] A: Laser power is 1500-2000W;

[0087] B: Laser power is 1750-1850W;

[0088] C: Feed speed is 15-21cm / min;

[0089] D: Feed speed is 18-20cm / min.

[0090] Exemplarily, the laser power can be 1750W, 1780W, 1780W, 1820W, 1850W, or any value between 1750-1850W, or an interval consisting of any values; the feed speed can be 15cm / min, 16cm / min, 17cm / min, 18cm / min, 19cm / min, 20cm / min, or any value between 15-21cm / min, or an interval consisting of any values.

[0091] Appropriate laser power and feed speed are conducive to forming a stable bonding interface. If the laser power and feed speed are too low or too high, the interface will be uneven and have large fluctuations, which is not conducive to improving the interface bonding strength and tissue uniformity. The laser power may increase the width of the transition layer, which is beneficial to improving corrosion resistance, but may have an adverse effect on interface stability. Reducing the power and increasing the feed speed will also reduce the width of the interface transition layer, and under low power conditions, undispersed Ti-Mo particles are easily formed at the interface, which is not conducive to interface bonding and corrosion resistance. Controlling the laser power within an appropriate range can reduce interface unevenness, improve interface bonding strength and tissue uniformity, and ensure good corrosion resistance.

[0092] As mentioned above, an embodiment of the present invention further provides an application of the aforementioned titanium-based corrosion-resistant material or the titanium-based corrosion-resistant material prepared by the aforementioned method in petrochemical industry or medical equipment.

[0093] The present invention will be described in detail below by way of examples. In the following examples, unless otherwise specified, all raw materials and instruments used are commercially available.

[0094] In the following examples, unless otherwise stated, the titanium substrate is TA2 industrial pure titanium.

[0095] Example 1

[0096] This embodiment provides a method for preparing a titanium-based corrosion-resistant material, comprising the following steps:

[0097] (1) Pretreatment of titanium substrate: The titanium substrate was cut into 20 mm × 15 mm × 3 mm pieces by wire cutting. The surface of the titanium substrate was then ground with 400-grit sandpaper and 1200-grit sandpaper, and finally polished with 5 μm diamond suspension and 0.3 μm silica suspension, respectively.

[0098] (2) Providing Ti-Mo alloy powder, wherein the particle size D50 of the Ti-Mo alloy powder is approximately 50 μm, the Ti content in the Ti-Mo alloy powder is 68 wt%, and the Mo content is 32 wt%, and the aforementioned Ti-Mo alloy powder is covered on the surface of a pretreated titanium substrate, and then the pure titanium surface is clad by laser cladding with a laser power of 1800 W and a feed speed of 18 cm / min to obtain a titanium-based corrosion-resistant material.

[0099] The average thickness of the transition layer in titanium-based corrosion-resistant materials is about 420 μm.

[0100] Example 2

[0101] This embodiment provides a method for preparing a titanium-based corrosion-resistant material, comprising the following steps:

[0102] (1) Pretreatment of titanium substrate: The titanium substrate was cut into 20 mm × 15 mm × 3 mm pieces by wire cutting. The surface of the titanium substrate was then ground with 400-grit sandpaper and 1200-grit sandpaper, and finally polished with 5 μm diamond suspension and 0.3 μm silica suspension, respectively.

[0103] (2) Providing Ti-Mo alloy powder, wherein the particle size D50 of the Ti-Mo alloy powder is approximately 50 μm, the Ti content in the Ti-Mo alloy powder is 68 wt%, and the Mo content is 32 wt%, and the aforementioned Ti-Mo alloy powder is covered on the surface of a pretreated titanium substrate, and then the pure titanium surface is clad by laser cladding with a laser power of 1500 W and a feed speed of 20 cm / min to obtain a titanium-based corrosion-resistant material.

[0104] The average thickness of the transition layer in titanium-based corrosion-resistant materials is about 320μm.

[0105] Example 3

[0106] This embodiment provides a method for preparing a titanium-based corrosion-resistant material, comprising the following steps:

[0107] (1) Pretreatment of titanium substrate: The titanium substrate was cut into 20 mm × 15 mm × 3 mm pieces by wire cutting. The surface of the titanium substrate was then ground with 400-grit sandpaper and 1200-grit sandpaper, and finally polished with 5 μm diamond suspension and 0.3 μm silica suspension, respectively.

[0108] (2) Providing Ti-Mo alloy powder, wherein the particle size D50 of the Ti-Mo alloy powder is approximately 50 μm, the Ti content in the Ti-Mo alloy powder is 68 wt%, and the Mo content is 32 wt%, and the aforementioned Ti-Mo alloy powder is covered on the surface of the pretreated titanium substrate, and then the pure titanium surface is clad by laser cladding with a laser power of 2000 W and a feed speed of 18 cm / min.

[0109] The average thickness of the transition layer in titanium-based corrosion-resistant materials is about 480μm.

[0110] Example 4

[0111] This embodiment provides a method for preparing a titanium-based corrosion-resistant material, which is carried out with reference to the method of Example 1, except that: in step (2), the particle size D50 of the Ti-Mo alloy powder is about 60 μm.

[0112] The average thickness of the transition layer of titanium-based corrosion-resistant material is about 425 μm.

[0113] Example 5

[0114] This embodiment provides a method for preparing a titanium-based corrosion-resistant material, which is carried out with reference to the method of Example 1, except that: in step (2), the Ti content in the Ti-Mo alloy powder is 65wt%, and the Mo content is 35wt%.

[0115] The average thickness of the transition layer of titanium-based corrosion-resistant material is about 430μm.

[0116] Comparative Example 1

[0117] This comparative example provides a method for preparing a titanium substrate control sample, including pretreatment of the titanium substrate: cutting the titanium substrate into a size of 20 mm × 15 mm × 3 mm using wire cutting, then grinding the surface of the titanium substrate with 400 grit sandpaper and 1200 grit sandpaper in sequence, and finally polishing the titanium substrate with a 5 μm diamond suspension and a 0.3 μm silica suspension in sequence.

[0118] In this comparative example, no subsequent cladding treatment was performed on the titanium substrate.

[0119] Analysis example 1

[0120] The cross-sections of the titanium-based corrosion-resistant materials obtained in Examples 1, 2 and 3 were analyzed by SEM and EDS. The specific analysis results are shown in Figure 1 .

[0121] in, Figure 1 (a1), (b1) and (c1) are respectively the cross-sectional SEM image, Ti element EDS distribution diagram and Mo element EDS distribution diagram of the titanium-based corrosion-resistant material in Example 2 of the present invention;

[0122] Figure 1 (a2), (b2) and (c2) are cross-sectional SEM images, Ti element EDS distribution diagrams and Mo element EDS distribution diagrams of the titanium-based corrosion-resistant material in Example 1 of the present invention;

[0123] Figure 1 (a3), (b3) and (c3) are the cross-sectional SEM images, Ti element EDS distribution diagrams and Mo element EDS distribution diagrams of the titanium-based corrosion-resistant material in Example 3 of the present invention.

[0124] from Figure 1 It can be seen that a transition layer is formed between the titanium substrate and the titanium-molybdenum alloy layer by laser cladding, and appropriate laser cladding power and feed rate are conducive to the formation of a stable interface structure.

[0125] Analysis example 2

[0126] The titanium-based corrosion-resistant materials obtained in Example 1 and Comparative Example 1 were subjected to corrosion resistance tests. The corrosion resistance test method is as follows:

[0127] Corrosion conditions: 110 mg / L fluorine; 69,000 mg / L chlorine; 2,500 mg / L magnesium; temperature 105°C; corrosion time 24 hours; pH = 1. Dynamic and static corrosion experiments were conducted in a custom-made, fully sealed, high-temperature and high-pressure resistant reactor. To prevent contact between the experimental solution and the reactor, the reactor liner was wrapped in polytetrafluoroethylene. During the experiment, a polytetrafluoroethylene-wrapped thermocouple directly measured the temperature of the solution in the reactor, achieving precise temperature control. After stabilization, the temperature error was ±0.3°C.

[0128] The dynamic corrosion experiment was simulated by magnetic stirring. The stirring speed was set to 1000 rpm. At this time, the solution showed a clear vortex flow state, which can simulate the effect of rapid solution flow and scouring the sample surface in the actual production process. The samples were suspended in the corrosion solution with polytetrafluoroethylene wire, and the sample spacing was 15 mm.

[0129] Post-corrosion characterization: The composition and valence state of the corrosion products were analyzed using an ESCALAB 250Xi X-ray photoelectron spectrometer (XPS). The experimental conditions were monochromatization of Al Kα (hv = 1486.6 eV). Specific test results are shown in Tables 1 and 2.

[0130] Table 1

[0131] Example 1 <![CDATA[Ti 0 ]]> <![CDATA[Ti 3+ (O)]]> <![CDATA[Ti 4+ (O)]]> <![CDATA[Ti 4+ (F)]]> <![CDATA[Mo 4+ ]]> <![CDATA[Mo 6+ ]]> <![CDATA[Mo metal ]]> <![CDATA[O 2- ]]> <![CDATA[OH - ]]> <![CDATA[H2O]]> Dynamic corrosion 33.17 13.08 49.42 4.34 74.30 14.40 11.30 53.53 32.72 13.75 Static corrosion 22.05 10.52 63.74 3.69 43.67 20.02 36.31 38.04 39.52 22.44

[0132] Table 2

[0133] Comparative Example 1 <![CDATA[Ti 0 ]]> <![CDATA[Ti 3+ (O)]]> <![CDATA[Ti 4+ (O)]]> <![CDATA[Ti 4+ (F)]]> <![CDATA[O 2- ]]> <![CDATA[OH - ]]> <![CDATA[H2O]]> Dynamic corrosion 21.39 17.38 52.48 8.75 60.58 12.76 22.66 Static corrosion 24.02 15.01 56.13 4.85 61.65 26.99 11.36

[0134] It can be seen from Table 1 and Table 2 that the titanium-based corrosion-resistant material obtained in the embodiment of the present invention has a high corrosion resistance after corrosion. 4+ (F) is significantly reduced, and the surface corrosion effect of fluoride ions is reduced.

[0135] Analysis example 3

[0136] The corrosion morphology of the sample corroded in Example 2 was observed using a ZEISS Sigma 300 field emission scanning electron microscope (SEM). The specific observation results are shown in Figure 2 and Figure 3 .

[0137] in, Figure 2 The SEM images of the titanium-based corrosion-resistant material before and after corrosion in Example 1 of the present invention are shown in FIG. Figure 2 In the figure, (a) is a SEM image of the titanium-based corrosion-resistant material in Example 1 of the present invention before corrosion, and (b) is a SEM image of the titanium-based corrosion-resistant material in Example 1 of the present invention after corrosion.

[0138] Figure 3 The SEM images of the titanium substrate before and after corrosion in Comparative Example 1 of the present invention are shown in FIG. Figure 3 In the figure, (a) is a SEM image of the titanium substrate before corrosion in Comparative Example 1 of the present invention, and (b) is a SEM image of the titanium base material after corrosion in Comparative Example 1 of the present invention.

[0139] from Figure 2 and Figure 3 It can be seen that the corrosion resistance of the titanium-based corrosion-resistant material obtained in the embodiment of the present invention is significantly improved, and the surface is relatively smooth after the corrosion test. After the corrosion test, the titanium substrate in Comparative Example 1 has obvious corrosion on the surface.

[0140] Analysis example 4

[0141] The corroded sample in Analysis Example 2 was used to study the electrochemical behaviors of the materials in Example 1 and Comparative Example 1 under different conditions using a CHI690 electrochemical workstation. The specific results are shown in Table 3.

[0142] Table 3

[0143] Open circuit potential, V Corrosion potential, V <![CDATA[Corrosion current density, μA / cm -2 <!-- 8 -->]]> Example 1 -0.05 -0.642 1.512 Comparative Example 1 -0.406 -0.5867 3.55

[0144] It can be seen from the above table that, compared with the titanium substrate that has not been subjected to the cladding treatment, the titanium-based corrosion-resistant material obtained in the embodiment of the present invention still has better electrochemical properties after corrosion.

[0145] Analysis example 5

[0146] The average weight loss and corrosion rate of the titanium-based corrosion-resistant materials of the examples and comparative examples under dynamic corrosion and static corrosion were tested and calculated. The specific results are shown in Table 4.

[0147] Test method: The samples were ultrasonically cleaned with deionized water and dried before and after the experiment. The samples were weighed and recorded 5 times using the same analytical balance. The highest and lowest values were removed, and the average of the middle three values was taken as the final weight to calculate the sample corrosion weight loss rate.

[0148] The corrosion rate R was calculated based on the average weight loss of three parallel samples using the following formula:

[0149] R = [8.76 × 10 4 ×(M-M1)] / (S×T×D), formula (1);

[0150] In formula (1), R is the corrosion rate in millimeters per year (mm / y); M is the mass of the sample before the test in grams (g); M1 is the mass of the sample after the test in grams (g); S is the total area of the sample in square centimeters (cm 2 ); T is the test time in hours (h); D is the material density (g / cm 3 ).

[0151] Table 4

[0152] Average weight loss by dynamic corrosion, mg Average weight loss from static corrosion, mg Example 1 0.10 0.37 Comparative Example 1 115.97 85.79

[0153] It can be seen from the above table that the titanium-based corrosion-resistant material obtained according to the embodiment of the present invention has significantly less weight loss after corrosion, and static corrosion causes greater damage to the material than dynamic corrosion.

[0154] Analysis example 6

[0155] The cross-section end of the titanium-based corrosion-resistant material of Example 1 was ground and polished, and then exposed to dilute acid for corrosion treatment. After the corrosion treatment, the interface was characterized by SEM and EDS. The results are shown in FIG. Figure 4 .

[0156] from Figure 4As can be seen in (a), after the acid corrosion treatment, fine corrosion pits are formed on the surface of the TA2 substrate, the titanium-molybdenum alloy layer has slight corrosion marks, and the transition layer has a smooth surface with few corrosion marks. Figure 4 As can be seen in (b), the surface corrosion of the transition layer is small, the CPS signal fluctuation is small, and it is relatively stable.

[0157] Analysis example 7

[0158] The cross-section ends of the titanium-based corrosion-resistant materials of Examples 1 and 2 were ground and polished, and then exposed to dilute acid for corrosion treatment. After the corrosion treatment, electron backscatter diffraction (EBSD) analysis was performed on the interface.

[0159] The results of Example 1 are shown in Figure 5 It can be seen that the grains of the titanium-molybdenum alloy layer are relatively small, while the grain size of the transition layer is larger than that of the titanium-molybdenum alloy layer and smaller than that of the TA2 substrate. Analysis software calculated that the average grain size of the titanium-molybdenum alloy layer is approximately 2.1μm, the average grain size of the transition layer is approximately 19.7μm, and the average grain size of the titanium substrate is approximately 86.2μm.

[0160] In Example 2, the average grain size of the titanium-molybdenum alloy layer is about 1.1 μm, the average grain size of the transition layer is about 18.5 μm, and the average grain size of the titanium substrate is about 86.8 μm.

[0161] It should be noted that the average grain size is obtained by statistically averaging the grain boundaries using the scattering diffraction image of EBSD and the division of the transition layer, titanium substrate, and titanium-molybdenum alloy layer using analysis software.

[0162] It should be noted that, in this article, the terms "comprises", "includes" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or apparatus that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements that are inherent to such process, method, article or apparatus.

[0163] The above technical solutions of the present invention are only preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made by using the contents of the present invention's description and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A titanium-based corrosion-resistant material, characterized in that: The invention comprises a titanium substrate and a corrosion-resistant layer provided on the surface of the titanium substrate, wherein the corrosion-resistant layer comprises a titanium-molybdenum alloy layer and a transition layer provided between the titanium-molybdenum alloy layer and the titanium substrate; the titanium content in the titanium substrate is not less than 90 wt%; The average grain size of the titanium substrate is D1, the average grain size of the transition layer is D2, and the average grain size of the titanium-molybdenum alloy layer is D3, wherein D1>D2>D3; The Mo content in the titanium substrate is A1, the Mo content in the transition layer is A2, and the Mo content in the titanium-molybdenum alloy layer is A3, wherein A1<A2<A3.

2. The titanium-based corrosion-resistant material according to claim 1, characterized in that: The thickness of the transition layer is not less than 5 μm; Optionally, the thickness of the transition layer is not less than 10 μm; Optionally, the thickness of the transition layer is not less than 20 μm; Optionally, the thickness of the transition layer is 20-1000 μm; Optionally, the average grain size D2 of the transition layer is 5-100 μm.

3. The titanium-based corrosion-resistant material according to claim 1, characterized in that: The Mo content A3 in the titanium-molybdenum alloy layer is not less than 25wt%; Optionally, the titanium-molybdenum alloy layer has a Ti content of 65-70 wt% and a Mo content A3 of 30-35 wt%; Optionally, the titanium-molybdenum alloy layer has a Ti content of 67-69 wt % and a Mo content A3 of 31-33 wt %; Optionally, the average grain size D3 of the titanium-molybdenum alloy layer is 0.5-10 μm.

4. The titanium-based corrosion-resistant material according to claim 1, characterized in that: The Ti content in the titanium substrate is not less than 95wt%; Optionally, the Ti content in the titanium substrate is not less than 99 wt %; Optionally, the average grain size D1 of the titanium substrate is 25-200 μm.

5. A method for preparing a titanium-based corrosion-resistant material, characterized in that: The following steps are involved: Provide Ti-Mo alloy powder; A titanium substrate is brought into contact with the Ti-Mo alloy powder and subjected to a cladding treatment to sequentially form a transition layer and a titanium-molybdenum alloy layer on the surface of the titanium substrate.

6. The method according to claim 5, characterized in that The particle size D50 of the Ti-Mo alloy powder is 50-60 μm.

7. The method according to claim 6, characterized in that The Mo content in the Ti-Mo alloy powder is not less than 25 wt %.

8. The method according to claim 5, characterized in that The conditions of the cladding process are controlled so that the thickness of the transition layer is greater than 5 μm.

9. The method according to claim 8, characterized in that The cladding treatment adopts a laser cladding method; Optionally, the laser cladding conditions meet one or more of the following conditions: A: Laser power is 1500-2000W; B: Laser power is 1750-1850W; C: Feed speed is 15-21cm / min; D: Feed speed is 18-20cm / min.

10. Use of the titanium-based corrosion-resistant material according to any one of claims 1 to 4 or the titanium-based corrosion-resistant material prepared by the method according to any one of claims 5 to 9 in petrochemical industry or medical equipment.

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