SE530515C2 - Cutting tool for metal machining such as turning, milling and drilling, comprises substrate of cemented carbide, cermet, ceramics, cubic boron nitride or high speed steel on which thin, adherent, hard and wear resistant coating is applied - Google Patents

Abstract

The cutting tool for metal machining such as turning, milling and drilling, comprises a substrate (1) of cemented carbide, cermet, ceramics, cubic boron nitride or high speed steel on which a thin, adherent, hard and wear resistant coating is applied. The coating comprises a first inner single layer or multilayer of metal carbides, nitrides or carbonitrides with a thickness of 0.2-20 mu m, an outer single layer or multilayer coating of metal carbides, nitrides or carbonitrides with a thickness of 0.2-5 mu m, and a laminated multilayer (2). The cutting tool for metal machining such as turning, milling and drilling, comprises a substrate (1) of cemented carbide, cermet, ceramics, cubic boron nitride or high speed steel on which a thin, adherent, hard and wear resistant coating is applied. The coating comprises a first inner single layer or multilayer of metal carbides, nitrides or carbonitrides with a thickness of 0.2-20 mu m, an outer single layer or multilayer coating of metal carbides, nitrides or carbonitrides with a thickness of 0.2-5 mu m, and a laminated multilayer (2) of alternating physical vapor deposition or plasma-enhanced chemical vapor deposition metal oxide layers such as Me 1X+Me 2X+Me 1X+Me 2X etc, where Me 1 and Me 2 are zirconium and aluminum. The Me 1X (3) is a combination of metal oxide and metal oxide nano-composite layer composed of two components with different composition and structure. The Me 2X (4) is crystalline alumina layer of alpha and gamma phase. The Me 1X and Me 2X have an individual thickness (5) of 1-30 nm. The components have a single phase oxide of a metal element or a solid solution of two or more metal oxides. The laminated multilayer has a total thickness of 0.2-20 mu m. The first component (40-95 vol.%) has an average grain size of 1-20 nm, and contains tetragonal or cubic zirconia. The second component (5-60 vol.%) has a mean linear intercept of 0.5-20 nm, and is amorphous or crystalline alumina.

Description

530 515 can thus be achieved by optimizing one or more of the above-mentioned properties.

Particle-reinforced ceramics are well known as bulk construction materials, but not as nanocomposites until recently. Bulk frames of alumina with different nanodispersed particles are described in J.F. Kuntz et al, MRS Bulletin Jan 2004, pp.22-27. Zirconia and titanium oxide cured alumina CVD layers are described in, for example, US 6,660,371, US 4,702,907 and US 4,701,384. In these later descriptions, the layers are precipitated with CVD technology and therefore the ZrO2 phase formed is the thermodynamically stable phase, i.e. the monoclinic phase. In addition, the CVD-coated layers generally have tensile or compressive stresses at a low level, while PVD or PECVD layers typically have a high level of compressive stresses due to an inherent nature of these coating processes. US 2005/0560432 discloses that blasting alumina + zirconia CVD layers provides a compressive stress level.

The blasting process is known for introducing compressive stresses in moderate levels.

Metastable phases of zirconia, such as tetragonal or cubic phases, have been shown to further improve bulk frames by a mechanism known as transformation hardening (Hannink et al., J. Er. Ceram. Soc 83 (3) 461-87; Evans, Er. Ceram. Soc 73 (2) 187-206 (1990)). additions of stabilizing elements such as Y or Ce or through Such metastable phases have been found to be promoted by the presence of an oxygen-poor environment, such as vacuum (Tomaszewski et al., J. Mater. Lett 7 (1988) 778-80), which is typically required in PVD applications. Variation of PVD process parameters has been shown to be Sci. cause variations in oxygen stoichiometry and the formation of metastable phases in zirconia, especially the cubic zirconia phase (Ben Amor et al., Mater. Sci. Eng. B57 (1998) 28).

PVD multilayers consisting of metal nitrides or metal carbides for cutting applications are described in EP 0709483 where a symmetrical multilayer structure of metal nitrides and metal carbides is described and US 6,103,357 which describes an aperiodic, laminated, multilayer of metal nitrides and metal carbides.

N 20 25 30 35 530 515 Swedish patent application no. SE 0500867-7 and SE 0600104-4 describe inserts for metalworking on which, at least on the functional parts of the surface thereof, a thin, adhesive, hard and durable coating is coated. The coating comprises a metal oxide + metal oxide nanocomposite layer consisting of two components with a grain size of 1 - 100 nm.

It is an object of the present invention to provide a PVD or PECVD coated cutting tool with improved wear properties in combination with improved resistance to thermally initiated breakdown.

Fig. 1 is a schematic representation of a cross section taken through a coated cutting tool according to the present invention showing a substrate (1) coated with an aperiodic, laminated, multilayer (2) with individual metal oxide + metal oxide nanocomposite layers Me1X (3), Me2X ( 4), each with an individual layer thickness (5). The order of the individual layer thicknesses is substantially aperiodic throughout the multilayer.

According to the present invention there is provided a cutting tool for metalworking such as turning, milling and drilling comprising a substrate of a hard alloy of cemented carbide, cermet, ceramic, cubic boron nitride or high speed steel, preferably cemented carbide or cermet, on top of which a durable coating comprising a laminated multilayer has been deposited. The shape of the cutting tool comprises indexable inserts as well as shank tools such as drills, end mills etc. The coating may further comprise, under the laminated multilayer, a first, inner single layer or multilayer of metal carbides, metal nitrides or metal carbonitrides where the metal atoms are one or more of Ti, Nb, V, Mo, Zr, Cr, Al, Hf, Ta, Y or Si with a thickness in the range 0.2 to 20 μm according to the prior art.

The coating is coated on top of the entire substrate or at least on the functional surfaces thereof, e.g. the cutting edge, the chip side, the release side and other surfaces involved in the metalworking process.

The coating of the invention, is firmly bonded to the substrate and comprises a laminated multilayer of alternating PVD or PECVD metal oxide layers, Me1X + Me2X + Me1X + Me2Xm, wherein the metal atoms Mel and Mez are one or more of Ti , Nb, V, Mo, Zr, Cr, Al, Hf, Ta, Y and Si, preferably Hf, Ta, Cr, Zr and Al, more preferably Zr and Al, and wherein at least one of Me1X and Me2X is a nanocomposite layer of a dispersed metal oxide component in a metal oxide matrix, hereinafter referred to as a metal oxide + metal oxide nanocomposite. The layers MeLX and Me2X are different in composition or structure or both of these properties.

The order of the individual Me1X or Me2X layer thicknesses is preferably aperiodic throughout the multilayer. By aperiodic is meant that the thickness of a particular individual layer in the laminated multilayer does not depend on the thickness of an individual layer immediately below nor does it have any relation to an individual layer above the particular individual layer. Therefore, the laminated multilayer has no repetition period in the order of the individual coating thicknesses. Furthermore, the individual layer thickness is greater than 0.4 nm but less than 50 nm, preferably greater than 5 nm and less than 20 nm. The laminated multilayer has a total thickness of between 0.2 and 20 μm, preferably 0.5 and 5 μm.

An individual metal oxide + metal oxide nanocomposite layer is composed of two components with different composition and different preferably greater than 1 nm and less than 30 nm, structure. Each component is an oxide of a phase with a metal element or a solid solution of two or more metal oxides. The microstructure of the material is characterized by nano-sized grains or columns of a component A with an average grain or column size of 1 - 100 nm, preferably 1 - 70 nm, preferably 1 - 20 nm, surrounded by component B.

The average linear average of the intercept length for component B is 0.5 - 200 nm, preferably 0.5 - 50 nm, most preferably 0.5 - 20 nm. p 1 The metal oxide + metal oxide nanocomposite layer is sub-stoichiometric in oxygen content with an oxygen: metal atomic ratio of 85-99%, preferably 90-97%, of the stoichiometric oxygen: metal-atomic ratio. The volume content of components A and B is 40-95%. respectively 5 - 60%.

In an exemplary embodiment of the invention, Me1X is a metal oxide + metal oxide nanocomposite layer containing grains or columns of component A, preferably in the form of tetragonal or cubic zirconia, and a surrounding component B, preferably in the form of amorphous or crystalline alumina which is one or both of the alpha (d) and gamma (V) phases, and Me2X is an Al2 O2 layer, and the gamma (y) phases. which is preferably one or both of alpha- (d) - In another exemplary embodiment of the invention, Me fi š is a metal oxide + metal oxide nanocomposite layer containing grains or columns of component A in the form of an oxide of hafnium and a surrounding component B in the form of amorphous or crystalline alumina being one or both of the alpha (a) and gamma (V) and Me2X is an Al 2 O 3 layer, both of the alpha (a) and gamma (V) phases. the phases, which are preferably one or In another exemplary embodiment of the invention, Mepš is a metal oxide + metal oxide nanocomposite layer containing grains or columns of component A and a surrounding component B, and Me2X is a metal oxide + metal oxide nanocomposite layer containing grains or columns of component A and a surrounding component B, wherein the metal atoms of component A in Me1X are different metal atoms in component A in Me2X and / or the metal atoms of component B in Me1X are different metal atoms in component B in Me fi h In another exemplary embodiment of the invention, Me1X is a metal oxide + metal oxide nanocomposite layer containing grains or columns of component A in the form of tetragonal or cubic zirconia and a surrounding component B in the form of amorphous or crystalline alumina, and Me2X is a metal oxide + metal oxide nanocomposite layer containing grains or columns of component A in the form of tetragonal or cubic zirconia and. an ambient component B in the form of amorphous or crystalline alumina, wherein the volume content of component A in Me1X is> the volume content of component A in Me2X, preferably the volume content of component A in Me1X is at least 2.5% more than the volume content of component A in Me2X in absolute units, the volume content of component A in Me1X at least 5% more than the volume content of component A in Me2X in absolute units. The laminated multilayer also has a residual stress as a result of the production method, a compressive stress in the range 200 and 5000 MPa, preferably 1000 and 3000 MPa. The coating may further comprise, on top of the laminated multilayer, an outer single layer or multilayer of metal carbides, metal nitrides or metal carbonitrides where the metal atoms are one or more of Ti, Nb, V, Mo, Zr, Cr, Al, Hf, Ta, Y and Si. The thickness of this layer is 0.2-5 μm.

The layer of the present invention is made by PVD technology, PECVD technology or a hybrid of such techniques. Examples of such techniques are RF (Radio Frequency) magnetron sputtering, DC magnetron sputtering and pulsed dual ("Dual" magnetron sputtering (DMS). The layer is formed at a substrate temperature of 200-850 ° C. When the type of PVD process allows, a metal oxide + metal oxide nanocomposite layer is deposited using a composite oxide source material. A reactive process using metallic sources in an ambient reactive gas is an alternative process path. In cases where the production of the metal oxide layers takes place by a magnetron sputtering method, two or more single metal sources can be used where the composition of the metal oxide + metal oxide nanocomposite is controlled by turning on and off separate sources. In a preferred method, the source is a compound having a composition corresponding to the desired layer composition.

In the case of RF sputtering, the composition is controlled by using independently controlled power levels to the separate sources.

The aperiodic layer structure can be formed by multiple rotation of the substrates in large-scale PVD or PECVD processes. * Example 1 An aperiodically laminated multilayer consisting of alternating metal oxide + metal oxide nanocomposite layer with Al 2 O 2; + ZrO2 and Al2O3 layers, precipitated on a substrate using an RF sputtering PVD method.

The nanocomposite layer was precipitated with a source of oxide of high purity under different process conditions in terms of temperature and the ratio of zirconia to alumina. The content of the two oxides in the formed nanocomposite layer was controlled by using a power level on the zirconia source and a separate power level on the alumina source. Alumina was added to the 530 515 zirconia flux with the aim of forming a composite material with metastable ZrO 2 phases. The power level of the sources in this case was 80 W for each oxide source. The sputtering speed was regulated to obtain a twice as high at-% zirconium compared to aluminum.

The oxygen: metal atom ratio was 94% of the stoichiometric oxygen: metal atom ratio Al 2 O 3 layer was precipitated using alumina sources in an argon atmosphere. 9 The resulting layers were analyzed by XRD and TEM.

X-ray diffraction analysis showed no traces of crystalline A143 in the nanocomposite layer, while the A120; layer consisted mainly of gamma-Al fl b.

The TEM study showed that the precipitated coating consisted of a laminated multilayer with alternating metal oxide + metal oxide nanocomposite layer, comprising grains with an average grain size of 4 nm (component A) surrounded by an amorphous phase with an average linear average of the intercept length of 2 nm (component B), and gamma-Al 2 O 3 layers. The grains in the nanocomposite layer were of cubic ZrO2 while the surrounding phase had a high aluminum content. The individual layer thicknesses ranged from 6 to 20 nm and the total multilayer thickness was about 1 μm.

The relative volume contents of the two components A and B were approximately 70% and 30%, respectively, as determined from ERDA analysis and EDS line scans from TEM images.

Example 2 A laminated multilayer coating consisting of alternating metal oxide + metal oxide nanocomposite layers of Al 2 O 2; + ZrO 2 and gamma Al 2 O 3 layers were deposited on a substrate using a reactive RF sputtering PVD method with high purity Al and Zr sources in an argon and oxygen atmosphere. The content of the two oxides in the formed layer was controlled by using a power level on the Zr source and a separate power level on the Al source.

The sputtering speeds were regulated with the aim of forming a composite material with 1-2 times higher at-% of zirconium. The algae layer was precipitated using aluminum sources in an argon + oxygen atmosphere.

5 X 5 X-ray diffraction results showed the presence of metastable ZrO 2 phases in the nanocomposite layer. The TEM study showed that the precipitated coating consisted of a laminated multilayer of alternating metal oxide + metal oxide nanocomposite layer, comprising grains with an average grain size of 6 nm (component A) surrounded by an amorphous phase with an average linear average of the intercept length of 3 nm (component B), and gamma-A145 layers.

The grains in the nanocomposite layer had a high zirconium content while the surrounding phase had a high aluminum content. The individual layer thicknesses ranged from 10 to 20 nm and the total multilayer thickness was about 3 μm.

The relative volume contents of the two components A and B were approximately 75% and 25%, respectively, as determined from ERDA analysis and EDS line scans from TEM images.

Example 3 A laminated multilayer coating consisting of two alternating metal oxide + metal oxide nanocomposite layers of Al 2 O 3 + ZrO 2 was deposited on a substrate using a double magnetron sputtering PVD method with Al + Zr sources of high purity in an argon and oxygen atmosphere. The content of the two oxides in the respective formed nanocomposite layers was controlled by the relative content of the two elements in the sources. The substrates were subjected to a triple rotation by rotation of the entire substrate table, the separate holders for the rods where the substrates are mounted and the individual rods.

The X-ray diffraction results showed the presence of metastable ZrO2 phases in the layers. The TEM study showed that the precipitated coating consists of a laminated multilayer of two alternating metal oxide + metal oxide nanocomposite layers, comprising grains with an average grain size of 6 nm (component A). The grains in the layers had a high zirconium content while the surrounding phase had a high aluminum content. The individual layer thicknesses ranged from 10 to 20 nm and the total multilayer thickness was about 3 μm. ERDA analysis and EDS line scans from TEM images revealed that the laminated multilayer consisted of alternating layers: a first layer type with a volume content of component A of about 70% and component B of about 30, and a second layer type 530 515 type with a volume content of component A of about 50% and component B of about 50%.

Claims (9)

10 U 20 25 30 35 530 515 N Krav A cutting tool for metalworking, comprising a cemented carbide substrate, cermet, ceramics, cubic boron nitride or high speed steel, the surface thereof a thin, adhesive, hard and durable coating is coated, characterized in that the coating comprises a laminated multilayer of alternating PVD or PECVD metal oxide layer, Me1X + Me2X + Me1X + Me2Xm, wherein the metal atoms Mel and Meg are one or more of Ti, Nb, V, Mo, Zr, Cr, Al, Hf, Ta, Y and Si, preferably Hf, Ta, Cr, Zr and Al, preferably Zr and Al, and wherein at least one of Me1X and Me2X is a metal oxide + metal oxide- for which at least on the functional parts of nanocomposite layers composed of two components, component A and component B, with different composition and different structure, the components of which consist of an oxide of a phase of a metal element or a solid solution of two or more metal oxides, wherein the layers Me1X and Me2X are different in composition or structure or both of these properties and have individual layer thicknesses vessels larger than 0.4 nm but less than 50 nm, and where the laminated multilayer has a total thickness of between 0.2 and 20 μm. 2. Cutting tools according to the preceding claims, characterized in that the individual Me1X and Me2X layer thicknesses are greater than 1 nm and less than 30 nm. Cutting tool according to any one of the preceding claims, characterized in that the coating further comprises a first, inner single layer or multilayer of metal carbides, metal nitrides or metal carbonitrides with a thickness between 0.2 and 20 μm, wherein the metal atoms are selected from one or more of Ti , Nb, V, Mo, Al, Hf, Ta, Y or Si. Cutting tool according to one of the preceding claims Zr, Cr, characterized in that the coating further comprises, on top of the laminated multilayer, an outer single-layer or multilayer coating of metal carbides, metal nitrides or metal carbonitrides with a thickness of between 0.2 and 5 μm, wherein the metal atoms are selected from one or more of Ti, Nb, V, Mo, Cr, Al, Hf, Ta, Y or Si. Zr, Cutting tool according to one of the preceding claims, characterized in that component A has an average grain size of 1 - 100 nm, preferably 1 - 70 nm, preferably 1 - 20 nm. W U 530 515 H Cutting tool according to one of the preceding claims, characterized in that component B has an average linear average value of the intercept length of 0.5 - 200 nm, preferably 0.5 - 50 nm, preferably 0.5 - 20 nm. Cutting tool according to one of the preceding claims, characterized in that the volume content of components A and B is 40 - 95% and 5 - 60%, respectively. Cutting tool according to one of the preceding claims, characterized in that component A contains tetragonal or cubic zirconia and component B consists of amorphous or crystalline alumina which is one or both of the alpha (d) and gamma (V) phases. Cutting tool according to one of the preceding claims, characterized in that Me1X is a metal oxide + metal oxide nanocomposite layer and Me2X is a crystalline alumina layer of one or both of the alpha (a) and gamma (V) phases.