An Al-Si-V-Nb titanium alloy wear-resistant coating containing an oxygen-free zone and a preparation method thereof

Abstract

The present invention discloses an Al-Si-V-Nb titanium alloy wear-resistant coating containing an oxygen-free zone and a preparation method thereof, which solves the wear resistance problem of titanium alloys. The coating comprises 10-25% Si by mass, 0.5-4% V by mass, 0-5% Nb by mass, and the remainder being Al. The coating has good wear resistance, and the coating structure is divided into three distinct regions, namely, the surface region structure, the oxygen-free region structure, and the matrix region structure. The present invention adopts laser deposition technology to prepare the titanium alloy wear-resistant coating, the process method is simple, the process is controllable, and the coating quality is good.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium alloy wear-resistant coating preparation, and particularly relates to an oxygen-free zone-containing Al-Si-V-Nb titanium alloy wear-resistant coating and a preparation method thereof. Background Art

[0002] Titanium and its alloys are widely used in aerospace, aviation, petroleum, and chemical industries due to their excellent comprehensive properties, including low specific gravity, high specific strength, corrosion resistance, high temperature resistance, non-magnetic properties, and weldability. Furthermore, titanium alloys exhibit high resistance to both high and low temperatures, earning them the nicknames "modern metals" and "space metals." However, due to their high coefficient of friction and relatively poor wear resistance, their application under friction and wear conditions is severely limited. Consequently, titanium alloy wear-resistant coatings and their preparation techniques have become a research hotspot in the field of titanium alloy surface strengthening, representing a long-awaited yet unresolved technical challenge in this field. Summary of the Invention

[0003] The present invention aims to provide an Al-Si-V-Nb titanium alloy wear-resistant coating containing an oxygen-free zone and a method for preparing the same, addressing the poor wear resistance of titanium alloys in the prior art. The coating comprises 10-25% Si by weight, 0.5-4% V by weight, 0-5% Nb by weight, and the remainder Al by weight. The coating's microstructure is divided into three distinct regions: a surface region, an oxygen-free region, and a matrix region. The coating exhibits excellent wear resistance. The hardness of the surface region is significantly lower than that of the titanium alloy matrix, while the hardness of the metallurgical bonding region (the oxygen-free region) between the coating and the matrix is generally slightly higher than that of the titanium alloy matrix. However, the alloy coating exhibits significantly improved wear resistance compared to the titanium alloy matrix. Unlike conventional titanium alloy wear-resistant coatings, the present invention avoids relying on increasing coating hardness to improve wear resistance. Instead, it improves the wear resistance of the titanium alloy by preparing a soft matrix and a fine hard phase dispersed within it. Its outstanding advantage is that the lower hardness of the coating substrate can ensure that the alloy coating has excellent toughness, and there is no need to worry about the problem of high hardness but insufficient toughness of the coating.

[0004] Another object of the present invention is to provide a method for preparing an Al-Si-V-Nb titanium alloy wear-resistant coating containing an oxygen-free zone. The preparation method adopts laser deposition preparation technology. The process is easy to implement, the process is controllable, and the process molding quality is high.

[0005] The technical solution of the present invention is:

[0006] The invention discloses an Al-Si-V-Nb titanium alloy wear-resistant coating containing an oxygen-free zone, wherein the mass percentage of Si element is 10-25%, the mass percentage of V element is 0.5-4%, the mass percentage of Nb element is 0-5%, and the rest is Al element.

[0007] The Al-Si-V-Nb titanium alloy wear-resistant coating containing an oxygen-free zone is characterized by having three distinct coating microstructures: a surface zone microstructure, an oxygen-free zone microstructure, and a matrix microstructure. The surface zone microstructure consists of primary Si microstructure, (a-Al+Si) eutectic microstructure, b-Ti-V solid solution, Si-Nb compounds, and an a-Al matrix. A distinct oxygen-free zone exists in the fusion zone between the coating and the matrix. The oxygen-free zone microstructure consists of a b-titanium alloy solid solution with fine in-situ Si phase, Ti-Al, Ti-Si, and Si-Nb intermetallic compounds distributed thereon. The matrix microstructure consists of a titanium alloy microstructure.

[0008] The Al-Si-V-Nb titanium alloy wear-resistant coating containing an oxygen-free zone is characterized in that: the coating and the substrate are completely metallurgically transitionally bonded, the surface microhardness of the cladding coating is 100-150HV, and the friction and wear resistance is 2-3 times that of the substrate; the hardness of the coating-substrate metallurgical bonding zone (oxygen-free zone) is 110-650HV, and the friction and wear resistance is 3-6 times that of the substrate.

[0009] The Al-Si-V-Nb titanium alloy wear-resistant coating containing an oxygen-free zone is characterized in that an oxygen-free zone of 5-20 mm exists in the metallurgical bonding area between the coating and the substrate, and the oxygen-free zone has high toughness.

[0010] The method for preparing the Al-Si-V-Nb titanium alloy wear-resistant coating containing an oxygen-free zone is characterized in that: Al-Si-V-Nb alloy powder is selected and laser deposition technology is used for cladding to form the coating.

[0011] The method for preparing an oxygen-free zone Al-Si-V-Nb titanium alloy wear-resistant coating is characterized in that: the laser deposition power is 800-1200 W, the argon flow rate is 10-15 mL / min, the scanning speed is 1-3 mm / s, and the defocus amount is 8-10 cm.

[0012] The design idea of the present invention is:

[0013] Al-Si alloy has good wear resistance, is cheap and lightweight. For the base titanium alloy, this can reduce the surface modification components while improving the wear resistance of the titanium alloy and maintaining the high specific strength of the titanium alloy.

[0014] V and Nb elements have high solid solubility in titanium alloys and are both stable b elements, which can form a b titanium alloy solid solution in the coating. At the same time, oxygen is a stable a phase element in titanium alloys, so an oxygen-free area is formed in the b titanium alloy solid solution. Because the b titanium alloy solid solution has good alloy toughness, a coating matrix with relatively good toughness is formed in the bonding area between the coating and the substrate. On the coating surface, the low hardness a-Al substrate can also form a coating matrix.

[0015] The atomic interactions between Ti-Si, Ti-V, Ti-Nb, and Ti-Al are relatively strong, easily forming dispersed, fine in-situ hard phases during coating preparation. Simultaneously, a large amount of hard phase Si can also form in the coating. These hard phases, when distributed on a flexible substrate, can produce a low-hardness, high-toughness titanium alloy wear-resistant coating.

[0016] Laser deposition manufacturing (LDM) is an additive manufacturing method that combines laser cladding with rapid prototyping to create a novel integrated manufacturing technology. Within the molten metal pool, material is accumulated layer by layer according to a predetermined scanning pattern. Laser deposition technology boasts short processing cycles, the absence of molds, and high material utilization. It has been widely used in surface modification of titanium alloys, high-temperature alloys, iron-based alloys, aluminum alloys, and ceramics.

[0017] The advantages and beneficial effects of the present invention are:

[0018] 1. The coating designed by the present invention is very effective in protecting titanium alloy from wear.

[0019] 2. The coating of the present invention adopts laser deposition technology, which has the advantages of short processing cycle and high material utilization rate.

[0020] 3. The coating of the present invention has the characteristics of low hardness and high wear resistance, avoiding the difficulty of strength-toughness matching of traditional titanium alloy wear-resistant coatings.

[0021] 4. The coating of the present invention can continue to maintain the advantage of high specific strength of titanium alloy.

[0022] 5. The present invention has low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Friction and wear properties of laser deposited coatings. DETAILED DESCRIPTION

[0024] In a specific embodiment, the present invention provides an oxygen-free zone Al-Si-V-Nb titanium alloy wear-resistant coating and its preparation method, wherein Al-Si-V-Nb alloy powder is selected, and a planetary fast grinder is used to mix Al, Si, V and Nb powders, wherein the particle size range of Al powder, Si powder, V powder and Nb powder is 100-120 mesh, the powder mixing speed is 100r / min, and the powder mixing time is 150min; a 3000W fiber laser is used for laser deposition, the laser deposition power is 800-1200W, the argon flow rate is 10-15mL / min, the scanning speed is 1-3 mm / s, and the defocusing amount is 8-10 cm. The Al-Si-V-Nb wear-resistant coating is prepared by cladding on a Ti-6Al-4V titanium alloy substrate, and the wear-resistant coating has a thickness of 0-3mm; the coating structure is divided into three distinct regions, namely the surface region structure, the oxygen-free region structure and the matrix region structure. The coating's surface layer consists of primary Si, (α-Al+Si) eutectic, β-Ti-V solid solution, Si-Nb compounds, and an α-Al matrix. A distinct oxygen-free zone exists within the fusion zone between the coating and the substrate. This zone consists of a β-titanium alloy solid solution with fine in-situ Si phases, Ti-Al, Ti-Si, and Si-Nb intermetallic compounds distributed above it. The substrate, however, is composed of a titanium alloy structure. This coating exhibits excellent wear resistance and stability, effectively addressing the wear resistance issues faced by titanium alloys.

[0025] The Al-Si-V-Nb titanium alloy wear-resistant coating containing an oxygen-free zone is characterized in that: the coating and the substrate are completely metallurgically transitionally bonded, the surface microhardness of the cladding coating is 100-150HV, and the friction and wear resistance is 2-3 times that of the substrate; the hardness of the coating-substrate metallurgical bonding zone (oxygen-free zone) is 110-650HV, and the friction and wear resistance is 3-6 times that of the substrate.

[0026] In the present invention, the laser deposition equipment is a 3000W fiber laser deposition equipment produced by Wuhan Ruifeng Optoelectronics Technology Co., Ltd.

[0027] In the present invention, the titanium alloy matrix is a Ti6Al4V matrix.

[0028] In order to make the technical solutions and advantages of the present invention more clear, a detailed description will be given below with reference to specific embodiments.

[0029] Example 1

[0030] Al-15Si-0.5V alloy powder with a particle size of 120 mesh was laser deposited on the surface of Ti6Al4V titanium alloy. The laser power was 900W, the argon flow rate was 10 mL / min, the scanning speed was 1 mm / s, and the defocus was 8 cm. The target oxygen-free zone Al-15Si-0.5V wear-resistant coating was prepared.

[0031] According to the traditional metallographic preparation method, the microstructure of the coating surface area was observed to be composed of primary Si structure, (a-Al+Si) eutectic structure, b-Ti-V solid solution and a-Al matrix; there was an obvious oxygen-free zone in the fusion zone between the coating and the matrix. GCr15 steel was selected as the friction pair material. The results showed that the wear resistance of the flexible wear-resistant coating in the oxygen-free zone of T6Al4V titanium alloy of the present invention is 2-6 times that of the substrate Ti6Al4V titanium alloy; the wear resistance of the oxygen-free zone is higher, such as Figure 1 shown.

[0032] Example 2

[0033] Laser deposition of 140-mesh Al-13Si-1V-2Nb alloy powder onto a Ti6Al4V titanium alloy surface was performed using a laser power of 1000W, an argon flow rate of 11 mL / min, a scanning speed of 2 mm / s, and a defocus distance of 9 cm. This resulted in a wear-resistant Al-13Si-1V-2Nb coating with a targeted oxygen-free zone. Microstructure observation, hardness testing, and friction and wear experiments revealed that the coating exhibited relatively good friction and wear resistance.

[0034] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent variation made to the above embodiment based on the essence of the invention technology shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. An Al-Si-V-Nb titanium alloy wear-resistant coating containing an oxygen-free zone, characterized in that: The mass percentage of Si element is 10-25%, the mass percentage of V element is 0.5-4%, the mass percentage of Nb element is 0-5%, and the rest is Al element; the coating structure is divided into three obvious regions, namely the surface region structure, the oxygen-free region structure and the matrix region structure; the structure of the surface region of the coating is primary Si structure, (α-Al+Si) eutectic structure, β-Ti-V solid solution, Si-Nb compound and α-Al matrix; there is an obvious oxygen-free zone in the fusion zone between the coating and the matrix, and the structure of the oxygen-free zone is β titanium alloy solid solution with fine in-situ Si phase, Ti-Al, Ti-Si and Si-Nb intermetallic compounds distributed on it; and the matrix region is titanium alloy structure.

2. The Al-Si-V-Nb titanium alloy wear-resistant coating containing an oxygen-free zone according to claim 1, characterized in that: The coating and the substrate are completely metallurgically transitionally bonded, the surface microhardness of the cladding coating is 100-150HV, and the friction and wear resistance is 2-3 times that of the substrate; the hardness of the oxygen-free zone is 110-650HV, and the friction and wear resistance is 3-6 times that of the substrate.

3. The Al-Si-V-Nb titanium alloy wear-resistant coating containing an oxygen-free zone according to claim 1, characterized in that: There is an oxygen-free zone of 5-20 μm in the metallurgical bonding area between the coating and the substrate, and the oxygen-free zone has higher toughness.

4. The method for preparing an oxygen-free zone Al-Si-V-Nb titanium alloy wear-resistant coating according to claim 1, characterized in that: Al-Si-V-Nb alloy powder is selected and cladding is performed using laser deposition technology to form a coating.

5. The method for preparing an oxygen-free zone Al-Si-V-Nb titanium alloy wear-resistant coating according to claim 4, characterized in that: The laser deposition power is 800-1200 W, the flow rate of argon is 10-15 mL / min, the scanning speed is 1-3 mm / s, and the defocus is 8-10 cm.

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