Wear-resistant cutter suitable for titanium and titanium alloy processing and preparation method thereof

Abstract

The invention discloses a wear-resistant cutter suitable for titanium and titanium alloy machining and a preparation method of the wear-resistant cutter, and relates to the technical field of surface coatings. The wear-resistant cutter coating sequentially comprises a Ti layer, a nano-multilayer structure TiB2 / ZrB2 layer and a ZrB2 surface layer from inside to outside, the Ti layer is formed by deposition through an evaporation plating or magnetron sputtering method, the nano-multilayer structure TiB2 / ZrB2 layer and the ZrB2 surface layer are formed by deposition through a magnetron sputtering method, the coatings of the three parts have different microstructures and effects, and the three parts are an organic whole with a synergistic effect. The wear-resistant cutter coating has excellent wear resistance and good cutter sticking resistance, and is suitable for milling titanium and titanium alloy under medium and high speed conditions.

Description

Technical Field

[0001] This invention belongs to the field of surface coating technology, specifically relating to a wear-resistant cutting tool suitable for machining titanium and titanium alloys and its preparation method. Background Technology

[0002] Titanium alloys and industrial pure titanium are widely used in aerospace, medical devices, and 3C electronics products due to their exceptional specific strength, corrosion resistance, and high-temperature properties. However, their poor machinability, particularly the tendency to form build-up edges (BUE) and severe tool wear during cutting, significantly limits their machining efficiency and economic feasibility. To address these challenges, researchers have been exploring high-performance tool coating materials to improve the machinability of titanium alloys and industrial pure titanium. Among these, titanium diboride (TiB2) coatings have emerged as promising candidates due to their high hardness, excellent resistance to diffusion wear, and self-lubricating properties.

[0003] TiB2-coated cutting tools have shown great potential in machining titanium alloys and industrial pure titanium, especially under low-to-medium speed machining conditions (below 100 m / min), where the self-lubricating properties and wear resistance of TiB2 coatings are superior to traditional coatings. However, due to the decomposition of B2O3 at temperatures of 400°C and above, the lubricating effect of the B2O3 friction film is greatly limited when TiB2 coatings are applied to high-speed machining of titanium alloys and industrial pure titanium. Therefore, researchers have been exploring the introduction of doping elements (such as Al, Cr, Si, W, and Nb) to optimize the mechanical properties and thermal stability of TiB2 coatings.

[0004] Numerous studies have shown that elemental doping significantly reduces the crystallinity of TiB2 coatings, leading to a sharp drop in hardness. Although the toughness of TiB2 coatings is improved to some extent, the overall wear resistance is not significantly enhanced. To address the limitations of TiB2 coatings, improving their microstructure is essential. Summary of the Invention

[0005] The purpose of this invention is to address the problems existing in the prior art by providing a wear-resistant cutting tool suitable for machining titanium and titanium alloys, and a method for preparing the same.

[0006] To achieve this objective, the technical solution provided by the present invention is: a wear-resistant cutting tool suitable for machining titanium and titanium alloys, wherein the wear-resistant cutting tool coating consists of a Ti layer, a nano-multilayer TiB2 / ZrB2 layer, and a ZrB2 surface layer from the inside out. The cutting tool to which the wear-resistant cutting tool coating is attached is a carbide end mill. The Ti layer connected to the cutting tool substrate has a dense columnar structure with a thickness of 50~200nm, the nano-multilayer TiB2 / ZrB2 layer has a thickness of 600~1000nm, and the ZrB2 surface layer has a dense fibrous structure with a thickness of 0~800nm.

[0007] Specifically, the wear-resistant tool coating has only a hexagonal ZrB2 crystal structure with a preferred orientation on the (0001) crystal plane.

[0008] Specifically, the nano-multilayer TiB2 / ZrB2 layer is composed of dozens of alternating TiB2 modulation layers and ZrB2 modulation layers. The thickness of both TiB2 and ZrB2 modulation layers is 5~20nm. The thickness of the TiB2 modulation layer gradually decreases from the inside to the outside, while the thickness of the ZrB2 modulation layer gradually increases from the inside to the outside. The thickness ratio of the TiB2 modulation layer to the ZrB2 modulation layer is 0.3~3.

[0009] Specifically, the atomic percentage of Zr in the ZrB2 surface layer is 32%~37%, and the atomic percentage of B is 63%~68%.

[0010] The present invention also provides a method for preparing a wear-resistant tool coating suitable for machining titanium and titanium alloys. The method includes cleaning the tool substrate to be deposited, argon ion etching, heating, deposition of a Ti layer connected to the tool substrate, deposition of a nano-multilayer TiB2 / ZrB2 layer, and deposition of a ZrB2 surface layer.

[0011] Specifically, the Ti layer deposited in connection with the tool substrate is deposited by electron beam evaporation of Ti blocks or by magnetron sputtering of a Ti target in an argon atmosphere. The bias voltage applied to the tool substrate during Ti layer deposition is -80 to -150V, and the deposition temperature is 300 to 500℃.

[0012] Specifically, the nano-multilayer TiB2 / ZrB2 layer is deposited by magnetron sputtering of a TiB2 target and a ZrB2 target under an argon atmosphere. The bias voltage applied to the tool substrate during the deposition of the nano-multilayer TiB2 / ZrB2 layer is -20 to -70V, and the deposition temperature is 250 to 400℃.

[0013] Specifically, the ZrB2 surface layer deposition is performed by magnetron sputtering on a ZrB2 target under an argon atmosphere. The bias voltage applied to the tool substrate during ZrB2 surface layer deposition is -30 to -60V, and the deposition temperature is 250 to 400℃.

[0014] Compared with existing technologies, the beneficial effects of this invention are as follows: This invention provides a wear-resistant tool coating suitable for machining titanium and titanium alloys, consisting of three parts with different compositions and structures, gradually progressing from the inside out to include a Ti layer, a nano-multilayer TiB2 / ZrB2 layer, and a ZrB2 surface layer. On one hand, the Ti layer, connected to the substrate, has a dense columnar structure, giving the coating excellent bonding performance, which is crucial for the overall effectiveness of the coating. On the other hand, the TiB2 / ZrB2 layer has a nanoscale multilayer structure. Firstly, the more inert Zr element is introduced into the TiB2 coating; secondly, the introduction of ZrB2 through a ZrB2 modulation layer does not cause degradation of the coating hardness; in fact, the "superhard effect" of the nano-multilayer structure can even improve the coating hardness; thirdly, the interlayer interface structure helps to alleviate coating stress and improve coating toughness by inducing the deflection of vertically propagating cracks. The varying TiB2 to ZrB2 layer modulation ratio is also designed to balance the coating's hardness and toughness, resulting in a coating with excellent comprehensive mechanical properties. Furthermore, using ZrB2 as the topcoat is based on the principle of "like dissolves like," avoiding direct contact between the Ti in the coating and the Ti in titanium and titanium alloys, thus reducing the tendency for tool sticking. In addition, ZrB2 itself has greater chemical inertness, making it more suitable for direct contact with the workpiece than TiB2. The combined effect of all parts of the coating gives it excellent adhesion, superior toughness, high hardness, and strong anti-sticking properties, resulting in excellent machining performance and a longer service life during the milling of titanium and titanium alloys. Attached Figure Description

[0015] Figure 1 The Rockwell indentation morphology of the wear-resistant tool coating suitable for machining titanium and titanium alloys provided in Embodiment 1 of the present invention under a 60kg load.

[0016] Figure 2 The image shows the Vickers indentation morphology of the wear-resistant tool coating suitable for machining titanium and titanium alloys provided in Embodiment 1 of the present invention under a 1kg load.

[0017] Figure 3 The Rockwell indentation morphology of the wear-resistant tool coating suitable for machining titanium and titanium alloys provided in Embodiment 2 of the present invention under a 60kg load.

[0018] Figure 4 The image shows the Vickers indentation morphology of the wear-resistant tool coating suitable for machining titanium and titanium alloys provided in Embodiment 2 of the present invention under a 1kg load.

[0019] Figure 5 The Rockwell indentation morphology of the tool coating provided in Comparative Example 1 under a 60kg load.

[0020] Figure 6 The Vickers indentation morphology of the tool coating provided in Comparative Example 1 under a 1kg load is shown. Detailed Implementation

[0021] The present invention will be further illustrated by specific embodiments below, but the scope of protection of the present invention is not limited to the following embodiments. Any non-creative modifications made by those skilled in the art based on the present invention shall fall within the scope of protection of the present invention. Example 1

[0022] The wear-resistant tool coating for machining titanium and titanium alloys, deposited on a carbide end mill, consists of a Ti layer, a nano-multilayer TiB2 / ZrB2 layer, and a ZrB2 facet layer, deposited from the inside out. The Ti layer, connected to the tool substrate, has a dense columnar structure with a thickness of 135 nm. The nano-multilayer TiB2 / ZrB2 layer has a thickness of 823 nm, and the ZrB2 facet layer has a dense fibrous structure with a thickness of 450 nm. XRD results show that the wear-resistant tool coating has only diffraction peaks oriented with the ZrB2 (0001) crystal plane, and the peak intensity reaches 3350 counts. The Ti layer was prepared by electron beam evaporation deposition, with a bias voltage of -120 V applied to the tool substrate during Ti layer deposition and a deposition temperature of 300 °C. The nanoscale multilayer TiB2 / ZrB2 layer was deposited by magnetron sputtering on TiB2 and ZrB2 targets under an argon atmosphere. The multilayer TiB2 / ZrB2 layer consisted of 40 alternating stacked TiB2 and ZrB2 modulation layers. The thickness of the TiB2 modulation layers gradually decreased from 14 nm to 7 nm from the inside out, while the thickness of the ZrB2 modulation layers gradually increased from 7 nm to 14 nm from the inside out. The thickness ratio of the TiB2 to ZrB2 modulation layers was 0.5–2. The bias voltage applied to the tool substrate during TiB2 / ZrB2 layer deposition was -40 V, and the deposition temperature was 300 °C. The ZrB2 surface layer was deposited by magnetron sputtering on a ZrB2 target under an argon atmosphere. The ZrB2 surface layer contained 34.5% Zr and 65.5% B atoms. The bias voltage applied to the tool substrate during ZrB2 deposition was -40V, and the deposition temperature was 300℃. Example 2

[0023] The wear-resistant tool coating for machining titanium and titanium alloys, deposited on a carbide end mill, consists of a Ti layer, a nano-multilayer TiB2 / ZrB2 layer, and a ZrB2 facet layer, deposited from the inside out. The Ti layer, connected to the tool substrate, has a dense columnar structure with a thickness of 111 nm. The nano-multilayer TiB2 / ZrB2 layer has a thickness of 1270 nm. XRD results show that the wear-resistant tool coating has only diffraction peaks with ZrB2 (0001) crystal plane orientation, and the peak intensity reaches 3300 counts. The Ti layer was prepared by electron beam evaporation deposition, with a bias voltage of -120 V applied to the tool substrate during Ti layer deposition and a deposition temperature of 300 °C. The nanoscale multilayer TiB2 / ZrB2 layer was deposited by magnetron sputtering on TiB2 and ZrB2 targets under an argon atmosphere. The TiB2 / ZrB2 layer consisted of 60 alternating stacked TiB2 and ZrB2 modulation layers. The thickness of the TiB2 modulation layers gradually decreased from 12 nm to 8 nm from the inside out, while the thickness of the ZrB2 modulation layers gradually increased from 9 nm to 13 nm from the inside out. The thickness ratio of the TiB2 modulation layers to the ZrB2 modulation layers was 0.62–1.33. The bias voltage applied to the tool substrate during the deposition of the nanoscale multilayer TiB2 / ZrB2 layer was -40 V, and the deposition temperature was 300 °C. The tool to which the coating was applied was a carbide end mill.

[0024] Comparative Example 1 The tool coating deposited on the carbide end mill consists of a Ti layer and a TiB2 surface layer, gradually forming from the inside out. The Ti layer, connected to the tool substrate, is a dense columnar structure with a thickness of 158 nm, while the TiB2 surface layer is a dense fibrous structure with a thickness of 560 nm. XRD results show that the tool coating has diffraction peaks with TiB2 (0001) and TiB2 (10'11) crystal plane orientations, with peak intensities below 230 counts for both. The Ti layer was deposited using electron beam evaporation deposition at a bias voltage of -120 V and a deposition temperature of 300 °C. The TiB2 surface layer was deposited using a TiB2 target under an argon atmosphere via magnetron sputtering. The Ti atomic percentage in the TiB2 surface layer is 36.5%, and the B atomic percentage is 63.5%. The Ti B2 surface layer was deposited at a bias voltage of -40 V and a deposition temperature of 300 °C.

[0025] The hardness of the coatings in Examples 1, 2, and Comparative Example 1 of this invention was tested using a nanoindenter and found to be 49.0 GPa, 48.0 GPa, and 51.2 GPa, respectively. Calculations show that compared to the Ti-TiB2 coating in Comparative Example 1, the hardness of the Ti-TiB2 / ZrB2-ZrB2 coating in Example 1 and the Ti-TiB2 / ZrB2 coating in Example 2 decreased by approximately 4% and 6%, respectively. This indicates that the new coating obtained after improving the coating structure using the technical solution of this invention still maintains the characteristic of high hardness, and the hard modulus ratio remains unchanged at 0.10. The Vickers indentation morphologies of the coatings in Examples 1, 2, and Comparative Example 1 are shown in the figures below. Figure 1 , Figure 3 and Figure 5 As shown in the figure, the Ti-TiB2 coating in Comparative Example 1 exhibited cracks around all four vertices of the rhomboid indentation, indicating significant brittleness. In Example 1 of this invention, the Ti-TiB2 / ZrB2-ZrB2 coating showed no obvious cracking around the vertices of the rhomboid indentation, with only slight cracking around one vertex. In Example 2, the Ti-TiB2 / ZrB2 coating did not crack around the vertices of the rhomboid indentation. Based on the cracking pattern around the vertices of the rhomboid indentation, it can be qualitatively determined that, compared to the unimproved Ti-TiB2 coating, the new coating obtained by improving the coating structure using the technical solution of this invention shows a significant improvement in toughness. Furthermore, the Rockwell indentation morphologies of the coatings in Examples 1, 2, and Comparative Example 1 are shown in the figure. Figure 2 , Figure 4 and Figure 6 As shown in the figure, the Ti-TiB2 coating in Comparative Example 1 experienced severe peeling around the circular indentation, indicating poor adhesion between the coating and the substrate. In Example 1 of this invention, the Ti-TiB2 / ZrB2-ZrB2 coating did not experience peeling around the circular indentation, but only cracks (radial cracks and annular cracks) appeared around the indentation. In Example 2, the Ti-TiB2 / ZrB2 coating also did not experience peeling around the circular indentation, but only radial cracks appeared around the indentation. It can be seen that the adhesion between the new coating obtained by improving the coating structure using the technical solution of this invention and the cemented carbide tool substrate has been significantly improved.

[0026] According to the performance test results, the wear-resistant tool coating for machining titanium and titanium alloys provided by this invention maintains high hardness while exhibiting superior toughness and adhesion, thus ensuring better wear resistance and a longer service life. Furthermore, the ZrB2 surface layer is a titanium-free coating, which reduces the chemical affinity between the coating and the titanium and titanium alloy workpiece, thereby mitigating adhesive wear. In summary, the beneficial effects of this invention are quite significant.

Claims

1. A wear-resistant cutting tool suitable for machining titanium and titanium alloys, characterized in that: The wear-resistant cutting tool includes a cutting tool base and a wear-resistant cutting tool coating disposed on the cutting tool base. The wear-resistant cutting tool coating consists of a Ti layer, a nano-multilayer TiB2 / ZrB2 layer, and a ZrB2 surface layer from the inside out. The wear-resistant cutting tool is a cemented carbide end mill. The Ti layer connected to the cutting tool base has a dense columnar structure with a thickness of 50~200nm. The nano-multilayer TiB2 / ZrB2 layer has a thickness of 600~1000nm. The ZrB2 surface layer has a dense fibrous structure with a thickness of 0~800nm.

2. The wear-resistant cutting tool suitable for machining titanium and titanium alloys according to claim 1, characterized in that: The wear-resistant tool coating has only one phase, ZrB2, with a hexagonal crystal structure and a preferred orientation on the (0001) crystal plane.

3. The wear-resistant cutting tool suitable for machining titanium and titanium alloys according to claim 1, characterized in that: The nano-multilayer TiB2 / ZrB2 layer is composed of dozens of alternating TiB2 modulation layers and ZrB2 modulation layers. The thickness of both TiB2 and ZrB2 modulation layers is 5~20nm. The thickness of the TiB2 modulation layer gradually decreases from the inside to the outside, while the thickness of the ZrB2 modulation layer gradually increases from the inside to the outside. The thickness ratio of the TiB2 modulation layer to the ZrB2 modulation layer is 0.3~3.

4. A wear-resistant cutting tool suitable for machining titanium and titanium alloys according to claim 1, characterized in that: The ZrB2 surface layer contains 32% to 37% Zr and 63% to 68% B.

5. A method for preparing a wear-resistant cutting tool, used to prepare the wear-resistant cutting tool suitable for machining titanium and titanium alloys as described in any one of claims 1-4, characterized in that: The method includes cleaning the substrate to be deposited, argon ion etching, heating, deposition of a Ti layer connected to the tool substrate, deposition of a nano-multilayer TiB2 / ZrB2 layer, and deposition of a ZrB2 surface layer.

6. The method for preparing a wear-resistant cutting tool according to claim 5, characterized in that: The Ti layer deposited on the tool substrate is achieved by electron beam evaporation of Ti blocks or by magnetron sputtering of a Ti target in an argon atmosphere. The bias voltage applied to the tool substrate during Ti layer deposition is -80 to -150V, and the deposition temperature is 300 to 500℃.

7. The method for preparing a wear-resistant cutting tool according to claim 5, characterized in that: The nano-multilayer TiB2 / ZrB2 layer was deposited by magnetron sputtering on a TiB2 target and a ZrB2 target under an argon atmosphere. The bias voltage applied to the tool substrate during the deposition of the nano-multilayer TiB2 / ZrB2 layer was -20 to -70V, and the deposition temperature was 250 to 400℃.

8. The method for preparing a wear-resistant cutting tool according to claim 5, characterized in that: The ZrB2 surface layer deposition is performed by depositing a ZrB2 target under an argon atmosphere using a magnetron sputtering method. The bias voltage applied to the tool substrate during ZrB2 surface layer deposition is -30 to -60V, and the deposition temperature is 250 to 400℃.

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