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US-12617022-B2 - Method of producing a coated cutting tool and a coated cutting tool

US12617022B2US 12617022 B2US12617022 B2US 12617022B2US-12617022-B2

Abstract

A method for producing a coated cutting tool for metal machining having a substrate and coating is provided. The coating includes at least one layer of (Ti,Al)N having a cubic crystal phase. The method includes the deposition of a layer of Ti 1-x Al x N, 0.70≤x≤0.98, the Ti 1-x Al x N having cubic crystal phase. The layer of Ti 1-x Al x N is deposited by cathodic arc evaporation at a vacuum chamber pressure of from 7 to 15 Pa of N 2 gas, using a DC bias voltage of from −200 to −400 V and using an arc discharge current of from 75 to 250 A. A coated cutting tool for metal machining having a coating including a (Ti,Al)N multi-layer of alternating sub-layers of at least Ti 1-y Al y N and Ti 1-z Al z N, 0.35≤y≤0.65 and 0.80≤z≤0.98, with only cubic phase present is also provided.

Inventors

  • Fredrik JOSEFSSON
  • Lars Johnson
  • Marta SARAIVA

Assignees

  • AB SANDVIK COROMANT

Dates

Publication Date
20260505
Application Date
20200617
Priority Date
20190619

Claims (7)

  1. 1 . A coated cutting tool for metal machining having a coating comprising a (Ti,Al) N multi-layer of alternating sub-layers of at least Ti 1-y Al y N and Ti 1-z Al z N, 0.35≤y≤0.65 and 0.80≤z≤0.98, with only cubic phase present in the form of a single phase cubic structure, an average individual (Ti,Al) N sub-layer thicknesses being from 1 to 20 nm, the (Ti,Al) N multi-layer is an aperiodic multi-layer, wherein the (Ti,Al) N multi-layer is a cathodic arc evaporation deposited multi-layer.
  2. 2 . The coated cutting tool according to claim 1 , wherein 0.40≤y≤0.6 and 0.85≤z≤0.96.
  3. 3 . The coated cutting tool according to claim 1 , wherein the average individual sub-layer thicknesses are from 1.5 to 5 nm.
  4. 4 . The coated cutting tool according to claim 1 , wherein the total thickness of the (Ti,Al) N multilayer is from 0.5 to 10 μm.
  5. 5 . The coated cutting tool according to claim 1 , wherein a substrate of the coated cutting tool is selected from the group of cemented carbide, cermet, ceramic, cubic boron nitride and high speed steel.
  6. 6 . The coated cutting tool according to claim 1 , wherein the coated cutting tool is a cutting tool insert, a drill, or a solid end-mill, for metal machining.
  7. 7 . The coated cutting tool according to claim 1 , wherein a ratio of thickness of the sub-layer Ti1-yAlyN to a thickness of the sub-layer Ti1-zAlzN is ≥0.5 and <3.

Description

RELATED APPLICATION DATA This application is a § 371 National Stage Application of PCT International Application No. PCT/EP2020/066801 filed Jun. 17, 2020 claiming priority to EP 19181096.9 filed Jun. 19, 2019. The present invention relates to a method of producing a coated cutting tool comprising a layer of (Ti,Al)N comprising cubic crystal structure and having a high aluminium content. The invention further relates to a coated cutting tool. INTRODUCTION (Ti,Al)N coatings made by physical vapour deposition (PVD) are commonly used in the area of cutting tools for metal machining. The crystal structure of (Ti,Al)N in PVD coatings can be cubic (NaCl (=B1)) structure or hexagonal (wurzite) structure. In prior art studies generally a lower Al content, such as <60% of Al+Ti, in (Ti,Al)N gives a cubic structure and a high Al content, such as >70%, gives a hexagonal structure. The specific limit of the level of Al content for giving either a single phase cubic structure or a mixed structure comprising both cubic and hexagonal structure have been reported and vary to some extent depending on, for example, the deposition conditions. A layer of single phase cubic (Ti,Al)N is known to possess good properties in terms of hardness and elastic modulus. These properties are beneficial to have for a coating of a cutting tool. For example, Tanaka et al., “Properties of (Ti1-xAlx)N coatings for cutting tools prepared by the cathodic arc ion plating method”, Journal of Vacuum Science & Technology A 10, 1749 (1992), reports (Ti1-xAlx)N films being single phase with a cubic B1 structure up to x=0.6 while a further increase in the aluminium content gave a wurtzite structure for x=0.85. Furthermore, Kimura et al., “Effects of Al content on hardness, lattice parameter and microstructure of (Ti1-xAlx)N films”, Surface and Coatings Technology 120-121 (1999) 438-441, reports (Ti1-xAlx)N films synthesized by the arc ion plating method where the NaCl structure for x≤0.6 changed into wurtzite structure for x≥0.7. WO2019/048507A1 discloses a method for producing a (Ti,Al)N film with high aluminium content by using High Power Pulse Magnetron Sputtering (HIPIMS) techniques, the film exhibiting a crystallographic cubic phase. When depositing (Ti,Al)N films by cathodic arc evaporation a bias voltage is applied and the reaction chamber has a certain level of nitrogen gas pressure. A usual level of bias voltage is from −30 to −150 V. The higher the voltage the higher energy in the plasma. A usual level of nitrogen gas pressure is from 2 to 6 Pa. The higher the pressure of nitrogen gas the higher the number of nitrogen molecules per volume. The nitrogen molecules dampen the energy of the ions and particles in the plasma. This effect is therefore more pronounced the higher the nitrogen pressure. Thus, when using a high level of bias voltage the nitrogen gas pressure has traditionally been kept low in order not to counter-act with the desired effect of using high bias voltage. It is an object of the present invention to provide a method for producing a (Ti,Al)N layer having a high aluminium content and still comprising a cubic crystal phase. There is a continuing demand for coated cutting tools in which the coating has good resistance to various types of wear such as flank wear and crater wear in order to provide long tool life in metal machining applications. Also, certain applications has high demands on edge line integrity of the cutting tool, i.e., a high edge line toughness is desired. Thus, it is a further object of the present invention to provide a coated cutting tool with good flank wear resistance and/or good crater wear resistance and/or good edge line toughness. THE INVENTION It has now been provided a method for producing a coated cutting tool for metal machining comprising a substrate and coating, the coating comprising at least one layer of (Ti,Al)N comprising cubic crystal phase and having a high aluminium content. The presence of cubic crystal phase in a layer of (Ti,Al)N is herein defined as the presence of one or more cubic peaks in theta-2theta XRD analysis. The method comprises deposition of a layer of Ti1-xAlxN, 0.70≤x≤0.98, Ti1-xAlxN comprises cubic crystal phase, the layer of Ti1-xAlxN is deposited by cathodic arc evaporation at a vacuum chamber pressure of from 7 to 15 Pa, preferably from 8 to 12 Pa of N2 gas, using a DC bias voltage of from −200 to −400 V, preferably from −250 to −350 V, and using an arc discharge current of from 75 to 250 A, preferably from 100 to 200 A. A (Ti,Al)N layer made according to the present method can be deposited as a single-layer. The thickness of the Ti1-xAlxN layer is then suitably from 0.2 to 10 μm, preferably from 0.5 to 5 μm. In one embodiment, the present method provides a single-layer (Ti,Al)N which comprises a cubic crystal structure at aluminium contents (Al out of Al+Ti) of at least up to 80 at % or even up to 85 at %. The cubic (Ti,Al)N phase may be present to an extent of being t