Method for improving performance of shield tunneling machine cutter based on nano material coatings with different thicknesses

Abstract

The invention provides a method for improving the performance of a shield tunneling machine cutter based on nanometer material coatings with different thicknesses, and belongs to the technical field of tunnel engineering construction equipment. The method comprises the following steps: firstly, carrying out surface cleaning and sand blasting roughening treatment on a cutter base body of the shield tunneling machine, and then sequentially preparing a nano cobalt-nickel alloy coating with the thickness of 2-3 microns as a bottom layer and a nano tungsten carbide-titanium carbide composite coating with the thickness of 5-8 microns as a middle layer on the surface of the treated cutter base body, the surface layer is a nano titanium carbide-nickel alloy coating with the thickness of 3-5 microns, annealing treatment and cooling are carried out, and the shield tunneling machine cutter with excellent performance is obtained. Compared with an uncoated cutter, the cutter prepared by the preparation method has the advantages that the wear resistance, the corrosion resistance and the impact toughness are remarkably improved, so that the service life is longer, the underwater cutter changing times and risks can be effectively reduced, and a powerful guarantee is provided for efficient tunneling of a shield tunneling machine.

Description

Technical Field

[0001] This invention relates to the field of tunnel construction equipment technology, specifically to a method for enhancing the wear resistance, corrosion resistance, and impact toughness of tunnel boring machine cutters using nanomaterial coatings of varying thicknesses. Background Technology

[0002] With the acceleration of urbanization and the continuous advancement of infrastructure construction, the scale of large-scale underground projects such as underwater tunnels is expanding daily. In the construction of underwater tunnels under high water pressure, the tunnel boring machine (TBM), as a key piece of equipment, directly affects construction efficiency and safety through the performance of its cutting tools. However, the high water pressure environment leads to frequent shutdowns for maintenance and cutter replacements underwater, not only wasting time and increasing costs but also significantly increasing the risks of TBM construction. Simultaneously, the corrosive nature of groundwater further exacerbates the wear and damage of the cutting tools. Therefore, researching how to enhance the wear resistance of the cutting tools and optimize their configuration to extend their service life and reduce the risks of underwater cutter replacement has become an urgent problem to be solved.

[0003] As a key component in tunnel construction, the performance of tunnel boring machine (TBM) cutters directly affects construction efficiency and cost. In recent years, WC-Co cemented carbide has been widely used in TBM cutter manufacturing due to its high hardness and wear resistance; however, its insufficient fracture strength and impact toughness limit performance improvement. Currently, methods to improve the performance of WC-Co cemented carbide include adding grain inhibitors, optimizing sintering processes, and surface coating treatments. Researchers have found that grain inhibitors such as VC and Cr3C2 can effectively suppress WC grain growth and improve alloy hardness, but their impact on overall performance is limited and may even reduce transverse fracture strength. Regarding sintering processes, vacuum sintering, hot pressing, isostatic pressing, and microwave sintering each have their advantages and disadvantages, making it difficult to simultaneously meet the requirements of high hardness, high toughness, and high wear resistance. For example, vacuum sintering can obtain high-density samples, but it consumes a lot of energy; hot pressing can increase sample density, but it suffers from uneven pressure distribution. Surface coating treatment enhances performance by preparing anti-corrosion or wear-resistant coatings on the surface of the cutting tool substrate. Among existing coating technologies, although diamond coatings have good wear resistance, the large performance gap between them and the cutting tool substrate makes them prone to peeling off during tunnel boring machine operation. This is because there is no effective transition between the coating and the substrate, and stress concentrates at the interface, resulting in poor bonding. Especially under complex working conditions, coating peeling damages the cutting tool, making repair difficult and increasing construction costs. Summary of the Invention

[0004] To address the shortcomings of the existing technologies, this invention provides a method for improving the performance of tunnel boring machine (TBM) cutters based on nanomaterial coatings of varying thicknesses. By preparing gradient nanomaterial coatings of different thicknesses on the surface of the TBM cutter substrate, the wear resistance, corrosion resistance, and impact toughness of the cutters are significantly enhanced, thereby extending the service life of the cutters and reducing the number of underwater cutter replacements and associated risks.

[0005] To achieve the above objectives, the specific technical solution of the present invention is as follows:

[0006] This invention provides a method for improving the performance of tunnel boring machine cutters based on nanomaterial coatings of different thicknesses, comprising the following steps:

[0007] S1. Pretreatment of the cutter body: The cutter body of the tunnel boring machine is cleaned and roughened by sandblasting.

[0008] S2. Preparation of gradient coatings of nanomaterials with different thicknesses: On the treated tool substrate surface, a bottom layer of 2-3 μm thick nano-cobalt-nickel (Co-Ni) alloy coating, a middle layer of 5-8 μm thick nano-tungsten carbide-titanium carbide (WC-TiC) composite coating, and a top layer of 3-5 μm thick nano-titanium carbide-nickel (TiC-Ni) alloy coating are sequentially prepared. The coated tool is then annealed to eliminate internal stress and improve bonding strength, followed by cooling to obtain a high-performance tunnel boring machine (TBM) tool. In the TBM tool with different thicknesses of nanomaterial coatings of this invention, the bottom layer of nano-cobalt-nickel alloy coating provides a good bonding force and toughness foundation for the tool, and a relatively thin thickness is set to avoid stress concentration; the middle layer of nano-tungsten carbide-titanium carbide composite coating provides excellent wear resistance for the tool, and a relatively thick thickness is set to extend the tool's service life; the top layer of nano-titanium carbide-nickel alloy coating provides high hardness, oxidation resistance, and corrosion resistance for the tool, and a moderate thickness is set to maintain excellent toughness.

[0009] Furthermore, the chemical composition of the nanomaterial coatings (bottom layer + intermediate layer + top layer) of different thicknesses is as follows: tungsten carbide (WC) 60% - 70%, titanium carbide (TiC) 20% - 30%, cobalt (Co) 5% - 10%, and nickel (Ni) 5% - 10%.

[0010] Furthermore, the surface cleaning treatment includes: ultrasonically cleaning the tunnel boring machine cutters with acetone or alcohol for 10-15 minutes to remove impurities such as oil and rust.

[0011] Furthermore, the process parameters for the sandblasting roughening treatment are: sandblasting pressure 0.2 - 0.4 MPa, sandblasting distance 100 - 150 mm, and sandblasting time 5 - 10 min, to increase the contact area and adhesion between the coating and the substrate.

[0012] Furthermore, methods for preparing coatings on the treated tool substrate surface include, but are not limited to, multi-arc ion plating, magnetron sputtering, chemical vapor deposition (CVD), spraying (e.g., plasma spraying), sol-gel method, or electroplating.

[0013] Furthermore, the process of preparing a coating on the treated tool substrate surface using multi-arc ion plating technology is as follows: Tungsten carbide, titanium carbide, cobalt, and nickel are mixed in proportion and then ball-milled to a particle size of 10-50 nm. Using multi-arc ion plating technology, a 2-3 μm thick nano-cobalt-nickel alloy coating is deposited sequentially on the treated tool substrate surface, followed by a 5-8 μm thick nano-tungsten carbide-titanium carbide composite coating, and a 3-5 μm thick nano-titanium carbide-nickel alloy coating. The coated tool is then annealed to eliminate internal stress and improve bonding strength, and cooled to obtain a high-performance tunnel boring machine tool.

[0014] Furthermore, the process parameters for the ball milling treatment are: ball milling time 10-15 h, ball-to-material ratio 10:1-15:1, and rotation speed 300-400 r / min.

[0015] Furthermore, using multi-arc ion plating technology, the deposition parameters for preparing the underlying nano-cobalt-nickel alloy coating are as follows: deposition temperature 200-250℃, deposition gas pressure 0.5-0.7 Pa, deposition rate 0.1-0.2 μm / min, deposition time 10-15 minutes (target thickness 2-3 μm), and substrate bias voltage -50 V to -100 V;

[0016] The deposition parameters for preparing the intermediate nano-tungsten carbide-titanium carbide composite coating are as follows: deposition temperature 250-300℃, deposition gas pressure 0.7-0.9 Pa, deposition rate 0.1-0.2 μm / min, deposition time 25-40 minutes (target thickness 5-8 μm), and substrate bias voltage -100 V to -150 V.

[0017] The deposition parameters for preparing the nano-titanium carbide-nickel alloy coating on the surface are: deposition temperature 250 - 300℃, deposition gas pressure 0.8 - 1.0 Pa, deposition rate 0.1 - 0.2 μm / min, deposition time 15 - 25 minutes (target thickness 3 - 5 μm), and substrate bias voltage -150 V to -200 V.

[0018] Furthermore, the process parameters for the annealing treatment are: annealing temperature 400-500 ℃, annealing time 1-2 h.

[0019] Furthermore, the cooling method is air cooling.

[0020] The present invention also provides high-performance tunnel boring machine cutters prepared using the method described above.

[0021] The present invention also provides a tunnel boring machine, including the high-performance tunnel boring machine cutter.

[0022] The present invention also provides the application of the tunnel boring machine in the construction of tunnels under high water pressure in rivers.

[0023] Compared with the prior art, the advantages of the present invention are:

[0024] This invention significantly enhances the wear resistance, corrosion resistance, and impact toughness of tunnel boring machine (TBM) cutter substrates by preparing nano-gradient coatings of varying thicknesses, thereby extending cutter lifespan and reducing the frequency and risks of underwater cutter replacements. Specifically:

[0025] (1) Improve the wear resistance of cutting tools: This invention fully utilizes the advantages of each nanomaterial by preparing a nano-gradient coating of different thicknesses from the inside to the outside on the surface of the cutting tool substrate. Among them, the bottom layer of nano-Co-Ni alloy can provide a good bonding force and toughness foundation, the middle layer of nano-WC-TiC composite material has excellent wear resistance, and the surface layer of nano-TiC-Ni alloy has high hardness and oxidation resistance. This nano-gradient coating design of different thicknesses in this invention can enable the cutting tool to effectively resist the wear of media such as hard rocks at the bottom of the river and effectively extend the service life of the cutting tool.

[0026] (2) Enhance the corrosion resistance of the cutting tool: The nano-gradient coating structure of different thicknesses in this invention is like putting on multiple layers of protective clothing for the cutting tool, which can effectively block the intrusion of corrosive groundwater in the riverbed under high water pressure, delay the corrosion process, improve the corrosion resistance of the cutting tool in complex and harsh environments, and ensure that the cutting tool can operate stably for a long time under corrosive working conditions such as the riverbed under high water pressure.

[0027] (3) Improve the impact toughness of the cutting tool: The nano-gradient coating system of different thicknesses of the present invention, while pursuing high hardness and wear resistance, also takes into account the impact toughness, so that the cutting tool can effectively reduce the damage caused by impact when facing impact loads under complex geological conditions, reduce the risk of tool breakage, and ensure the smooth progress of tunnel construction. Compared with traditional cutting tools, the service life is extended by 1-2 times in impact environment, and the risk of underwater tool replacement is reduced by 50%-70%.

[0028] (4) Adapting to complex and ever-changing construction environments: The nano-gradient coating of different thicknesses of this invention endows the cutting tool with excellent comprehensive performance, enabling it to better adapt to the complex and ever-changing geological conditions in the construction of tunnels under high water pressure. Whether facing the strong wear of hard rock layers, the chemical erosion of corrosive groundwater, or the impact load in complex geology, the cutting tool can maintain good working performance, providing a strong guarantee for the efficient tunneling of the shield machine.

[0029] (5) Significant economic benefits: Although preparing a nano-gradient coating on the surface of the cutting tool will increase the preparation cost to a certain extent, considering the significant extension of the tool's service life and the significant reduction in the number of underwater tool replacements, the overall construction cost is greatly reduced and the construction efficiency is improved, resulting in significant economic benefits. It is especially suitable for shield tunneling projects with stringent requirements for cutting tool performance, such as large-scale, long-distance and high-water-pressure riverbed tunnel projects. Attached Figure Description

[0030] Figure 1 The diagram shows the structure of the cutting tool prepared by the method of the present invention; wherein, 1 represents the TiC-Ni alloy coating; 2 represents the WC-TiC composite coating; 3 represents the Co-Ni alloy coating; and 4 represents the shield machine cutting tool substrate. Detailed Implementation

[0031] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] This invention provides a method for improving the performance of tunnel boring machine cutters based on nanomaterial coatings of different thicknesses, comprising the following steps:

[0033] S1. Pretreatment of the cutter body: The cutter body of the tunnel boring machine is cleaned and roughened by sandblasting.

[0034] S2. Preparation of gradient coatings of nanomaterials with different thicknesses: On the treated tool substrate surface, a bottom layer of 2-3 μm thick nano-cobalt-nickel (Co-Ni) alloy coating, a middle layer of 5-8 μm thick nano-tungsten carbide-titanium carbide (WC-TiC) composite coating, and a top layer of 3-5 μm thick nano-titanium carbide-nickel (TiC-Ni) alloy coating are sequentially prepared. The coated tool is then annealed to eliminate internal stress and improve bonding strength, followed by cooling to obtain a high-performance tunnel boring machine (TBM) tool. In the TBM tool with different thicknesses of nanomaterial coatings of this invention, the bottom layer of nano-cobalt-nickel alloy coating provides a good bonding force and toughness foundation for the tool, and a relatively thin thickness is set to avoid stress concentration; the middle layer of nano-tungsten carbide-titanium carbide composite coating provides excellent wear resistance for the tool, and a relatively thick thickness is set to extend the tool's service life; the top layer of nano-titanium carbide-nickel alloy coating provides high hardness, oxidation resistance, and corrosion resistance for the tool, and a moderate thickness is set to maintain excellent toughness.

[0035] In some examples, the chemical composition of the nanomaterial coatings (bottom layer + intermediate layer + top layer) of different thicknesses is as follows: tungsten carbide (WC) 60% - 70%, titanium carbide (TiC) 20% - 30%, cobalt (Co) 5% - 10%, and nickel (Ni) 5% - 10%.

[0036] In some examples, the surface cleaning treatment includes: ultrasonically cleaning the tunnel boring machine cutters with acetone or alcohol for 10-15 minutes to remove impurities such as oil and rust; the process parameters for the sandblasting roughening treatment are: sandblasting pressure 0.2-0.4 MPa, sandblasting distance 100-150 mm, and sandblasting time 5-10 minutes to increase the contact area and adhesion between the coating and the substrate.

[0037] In some examples, methods for preparing coatings on the treated tool substrate surface include, but are not limited to, multi-arc ion plating, magnetron sputtering, chemical vapor deposition (CVD), spraying (e.g., plasma spraying), sol-gel method, or brush plating.

[0038] In the following specific embodiment, a coating is prepared on the surface of the treated tool substrate using multi-arc ion plating technology. The specific operation is as follows: Tungsten carbide, titanium carbide, cobalt, and nickel are mixed in a certain proportion and ball-milled to a particle size of 10-50 nm. Multi-arc ion plating technology is used, with the following deposition parameters: deposition temperature 200-250℃, deposition pressure 0.5-0.7 Pa, deposition rate 0.1-0.2 μm / min, deposition time 10-15 minutes, and substrate bias voltage -50 V to -100 V. A nano-cobalt-nickel alloy coating with a thickness of 2-3 μm is deposited on the surface of the treated tool substrate. The following deposition parameters are set: deposition temperature 250-300℃, deposition pressure 0.7-0.9 Pa, deposition rate 0.1-0.2 μm / min, deposition time 25-40 minutes, and substrate bias voltage -100 V to -150 V. An intermediate layer with a thickness of 5-8 μm is deposited on the surface of the bottom layer. A nano-tungsten carbide-titanium carbide composite coating with a thickness of μm was prepared. The deposition parameters were set as follows: deposition temperature 250-300℃, deposition gas pressure 0.8-1.0 Pa, deposition rate 0.1-0.2 μm / min, deposition time 15-25 minutes, and substrate bias voltage -150 V to -200 V. A nano-titanium carbide-nickel alloy coating with a thickness of 3-5 μm was deposited on the surface of the intermediate layer. The prepared coated tool was annealed at 400-500 ℃ for 1-2 h to eliminate internal stress and improve bonding strength. After cooling, a shield machine tool with excellent performance was obtained.

[0039] Example 1

[0040] A high-performance tunnel boring machine cutter has a gradient coating of nanomaterials of different thicknesses (bottom layer + intermediate layer + surface layer) with the following chemical composition: WC 65%, TiC 25%, Co 7%, Ni 3%.

[0041] The method for preparing the high-performance tunnel boring machine cutter includes the following steps:

[0042] (1) Preparation of coating raw materials

[0043] Tungsten carbide, titanium carbide, cobalt, and nickel were mixed in proportions of 65% WC, 25% TiC, 7% Co, and 3% Ni, and then poured into a ball mill. The mixture was ball-milled for 12 hours at a speed of 350 r / min with a ball-to-material ratio of 12:1 to obtain a mixed material with a particle size of 10-50 nm.

[0044] (2) Pretreatment of the tool substrate

[0045] The substrate of the tunnel boring machine cutter was ultrasonically cleaned with acetone for 12 minutes to remove impurities such as oil and rust; then it was roughened by sandblasting for 8 minutes at a pressure of 0.3 MPa and a distance of 120 mm to increase the contact area and adhesion between the coating and the substrate.

[0046] (3) Preparation of nanogradient coatings of different thicknesses

[0047] Using the mixed material from step (1) as raw material, a bottom layer, an intermediate layer, and a top layer coating are sequentially prepared on the surface of the treated tool substrate using multi-arc ion plating technology. The deposition parameters are as follows:

[0048]

[0049] (4) Post-coating treatment

[0050] The coated cutting tools were annealed in an annealing furnace at 450 °C for 1.5 h and then air-cooled to obtain high-performance tunnel boring machine cutting tools.

[0051] (5) Tool performance test

[0052] Hardness test: The hardness of the prepared tunnel boring machine cutter was tested using a Rockwell hardness tester. The results showed that the surface hardness of the tunnel boring machine cutter prepared by the present invention reached HRC72, which is about 35% higher than that of the uncoated cutter, indicating that the tunnel boring machine cutter of the present invention has good wear resistance.

[0053] Corrosion resistance test: The prepared tunnel boring machine cutter was placed in a 3.5% NaCl solution for electrochemical corrosion test. The results showed that the corrosion current density of the tunnel boring machine cutter prepared by the present invention was reduced to 20% of that of the uncoated cutter, indicating that the tunnel boring machine cutter of the present invention has good corrosion resistance.

[0054] Impact toughness test: The prepared tunnel boring machine cutter was subjected to impact toughness test using an impact testing machine. The results showed that the impact toughness value of the tunnel boring machine cutter prepared by this invention reached 18 J / cm. 2 Compared to uncoated cutters, the impact toughness is improved by about 40%, indicating that the tunnel boring machine cutters of the present invention have good impact toughness.

[0055] In summary, this invention first cleans and roughens the surface of the tunnel boring machine (TBM) cutter substrate through sandblasting. Then, it sequentially prepares a bottom layer of 2-3 μm thick nano-cobalt-nickel alloy coating, a middle layer of 5-8 μm thick nano-tungsten carbide-titanium carbide composite coating, and a top layer of 3-5 μm thick nano-titanium carbide-nickel alloy coating. After annealing and cooling, a high-performance TBM cutter is obtained. Compared to uncoated cutters, the cutters prepared by this invention exhibit significantly improved wear resistance, corrosion resistance, and impact toughness, resulting in a longer service life. Furthermore, it effectively reduces the frequency and risks of underwater cutter replacement, providing a strong guarantee for the efficient tunneling of the TBM.

[0056] The above detailed embodiments describe the implementation of the present invention; however, the present invention is not limited to the specific details described in the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. A method for improving the performance of tunnel boring machine cutters based on nanomaterial coatings of different thicknesses, characterized in that, Includes the following steps: The shield machine cutter body is subjected to surface cleaning and sandblasting roughening treatment; After treatment, a nano-cobalt-nickel alloy coating with a thickness of 2-3 μm is sequentially prepared on the surface of the tool substrate, followed by a nano-tungsten carbide-titanium carbide composite coating with a thickness of 5-8 μm, and a nano-titanium carbide-nickel alloy coating with a thickness of 3-5 μm. After annealing and cooling, a high-performance tunnel boring machine tool is obtained.

2. The method for improving the performance of tunnel boring machine cutters based on nanomaterial coatings of different thicknesses according to claim 1, characterized in that, The chemical composition of the nanomaterial coatings of different thicknesses is as follows: tungsten carbide 60% - 70%, titanium carbide 20% - 30%, cobalt 5% - 10%, and nickel 5% - 10%.

3. The method for improving the performance of tunnel boring machine cutters based on nanomaterial coatings of different thicknesses according to claim 1, characterized in that, The surface cleaning treatment includes: ultrasonic cleaning of the tunnel boring machine cutters with acetone or alcohol for 10-15 minutes; the process parameters for the sandblasting roughening treatment are: sandblasting pressure 0.2-0.4 MPa, sandblasting distance 100-150 mm, and sandblasting time 5-10 minutes.

4. The method for improving the performance of tunnel boring machine cutters based on nanomaterial coatings of different thicknesses according to claim 1, characterized in that, Methods for preparing coatings on the treated tool substrate surface include, but are not limited to, multi-arc ion plating, magnetron sputtering, chemical vapor deposition, spraying, sol-gel, or electroplating.

5. The method for improving the performance of tunnel boring machine cutters based on nanomaterial coatings of different thicknesses according to claim 4, characterized in that, The process of preparing a coating on the surface of the treated tool substrate using multi-arc ion plating technology is as follows: Tungsten carbide, titanium carbide, cobalt, and nickel are mixed in a certain proportion and then ball-milled. Using multi-arc ion plating technology, a 2-3 μm thick nano-cobalt-nickel alloy coating is deposited sequentially on the surface of the treated tool substrate, followed by a 5-8 μm thick nano-tungsten carbide-titanium carbide composite coating and a 3-5 μm thick nano-titanium carbide-nickel alloy coating. The coated tool is then annealed to eliminate internal stress and improve bonding strength, and cooled to obtain a high-performance tunnel boring machine tool.

6. The method for improving the performance of tunnel boring machine cutters based on nanomaterial coatings of different thicknesses according to claim 5, characterized in that, The deposition parameters for preparing the underlying nano-cobalt-nickel alloy coating using multi-arc ion plating technology are as follows: deposition temperature 200 - 250℃, deposition gas pressure 0.5 - 0.7 Pa, deposition rate 0.1 - 0.2 μm / min, deposition time 10 - 15 minutes, and substrate bias voltage -50 V to -100 V. The deposition parameters for preparing the intermediate nano-tungsten carbide-titanium carbide composite coating are as follows: deposition temperature 250 - 300℃, deposition gas pressure 0.7 - 0.9 Pa, deposition rate 0.1 - 0.2 μm / min, deposition time 25 - 40 min, and substrate bias voltage -100V to -150V. The deposition parameters for preparing the nano-titanium carbide-nickel alloy coating on the surface are: deposition temperature 250 - 300℃, deposition gas pressure 0.8 - 1.0 Pa, deposition rate 0.1 - 0.2 μm / min, deposition time 15 - 25 min, and substrate bias voltage -150 V to -200 V.

7. The method for improving the performance of tunnel boring machine cutters based on nanomaterial coatings of different thicknesses according to claim 1, characterized in that, The annealing process parameters are: annealing temperature 400-500 ℃, annealing time 1-2 h.

8. A high-performance tunnel boring machine cutter prepared by the method described in any one of claims 1-7.

9. A tunnel boring machine (TBM) for tunnel construction, characterized in that, Including the high-performance tunnel boring machine cutter described in claim 8.

10. The application of the tunnel boring machine as described in claim 9 in the construction of tunnels under high water pressure in rivers.

Images