SE530945C2 - Cutting tools coated with laminated nanocomposite layers of metal oxides - Google Patents

Description

530 945 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 4,702,97O 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 stresses 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 describes that blasting CVD layers of alumina + zirconia gives 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 conversion curing (Hannink et al, J.

Your. Ceram. Soc 83 (3) 461-87; Your. (2) 187-206 (1990)). Such metastable phases have been found to be promoted by the addition of stabilizing elements such as Y or Ce or 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 cause variations in oxygen stoichiometry and formation of metastable phases in zirconia, especially the cubic zirconia phase (Ben Amor et al., Mater. Sci. Eng. B57 (1998) 28).

PVD multilayer consisting of metal nitrides or metal carbides for cutting applications is 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.

Evans, Ceram. Soc. 73 Sci. 10 Ü 20 25 30 35 53Ü 945 Swedish patent application no. SE 0500867-7 and SE 0600104-4 describe inserts for metal working 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 where the coating has improved wear resistance in combination improved adhesion properties.

Fig. 1 is a schematic representation of a cross section taken through a coated cutting tool of the present invention showing a substrate, A, coated with a laminated multilayer, B, comprising alternating metal oxide + metal oxide-nanocomposite layer type C and metal oxide + metal oxide-nanocomposite layer of type D.

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, ceramics, cubic boron nitride or high speed steel, preferably cemented carbide or cermet, on top of which a durable coating has a laminated multilayer. . 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, below the laminated multilayer, at least a first, inner single layer or multilayer of metal carbides, metal nitrides or metal carbonitrides , 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 according to the invention, is firmly bonded to the substrate and comprises a laminated multilayer with alternating PVD or PECVD metal oxide layers, Me1X + Me2X + Me1X + Me2Xm, where 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, Zr and Al, more preferably Zr and Al, and wherein at least one of MeLX 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, and wherein the laminated multilayer has a composition gradient, with respect to the concentration of one or more of the metal atoms in the direction from the outer surface of the coating to the substrate. the average concentration in the outermost region of the multilayer and the average concentration in the innermost region of the multilayer is at least 5 at-% in absolute units. The layers Me1X 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 on top of 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 1 nm and less than 30 nm, more 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 at least two components with different composition and different 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 a 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.

The metal oxide + metal oxide nanocomposite layer may be sub-stoichiometric in oxygen content with an oxygen-metal atomic ratio of 85-99%, preferably 90-97%, of the stoichiometric oxygen: metal-atom ratio.

The volume content of components A and B is 40-95% and 5-60%, respectively.

In an exemplary embodiment of the invention, the laminated multilayer is deposited directly on top of 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, M0, zr, cr, A1, Hf, fra , Y and si with a thickness in the range 0.2 to 20 μm, where one or more of the metal atoms of at least one metal oxide + metal oxide nanocomposite layer is a stronger carbide or nitride former than one or more of the metal atoms in the first, inner single layer or multilayer.

In addition, it is preferred, in the laminated multilayer, that the concentration of the metal atoms which are the stronger carbide or nitride formers in at least one metal oxide + metal oxide nanocomposite layer increase in the direction from the outer surface of the coating to the substrate.

In an exemplary embodiment of the present invention, Megx 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.

Component A in Me1X is the same as component A in Me3X which is component B in Me1X and Me2X, but the metal atoms in component A are different metal atoms in component B. The volume content of component A in Me1X is> the volume content of component A in Me2X, preferably is 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, most preferably the volume content of component A in Me1X is at least 5% more than the volume content of component A in Me2X in absolute units. The laminated multilayer has a composition gradient of the metal atoms in component A, as well as a composition gradient of the metal atoms in component B, the direction of an increasing metal atom content in the laminated multilayer is opposite for component A and component B, due to a change in the ratio of the average Me1X and / or the Me2X layer thicknesses through the multilayer. In another exemplary embodiment of the present invention, MegX is a metal oxide + metal oxide nanocomposite layer and Me2X is a metal oxide + metal oxide nanocomposite layer. The metal atoms in component A of Me1X are different metal atoms in component A of Me2X.

Component B in Me1X is the same as component B in Me2X. Ö The volume content of component A in Me1X is equal to the volume content of component A in Me2X. The laminated multilayer has a composition gradient of metal atoms in component A, due to a change in the ratio of the average Me1X and / or Me2X layer thicknesses through the multilayer. The average content of metal atoms in component A of Me1X can e.g. be close to zero percent in the innermost part of the multilayer, ie. the average Me1X layer thickness is close to zero, therefore the average content of metal atoms in component A of Me2X is maximized.

The average content of metal atoms in component A of Me1X may increase to a maximum content towards the outermost part of the multilayer due to a gradually increasing average Me1X layer thickness towards the outermost part of the multilayer.

In another exemplary embodiment of the present invention, the first, inner single layer or multilayer comprises a Ti-based carbide, nitride or carbonitride. 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 alpha- (d) and the gamma (y) phases, and Me2X is an Al2 O; layer, preferably being one or both of the alpha (d) and gamma (V) phases. The laminated multilayer has a composition gradient of metal atoms in component A, due to a change in the ratio of average Me1X and / or Me2X layer thicknesses through the multilayer.

In another embodiment, the first, inner single layer or multilayer comprises a Ti-based carbide, nitride or carbonitride. Me1X 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 which is one or both of alpha- (d) - and 530 945 the gamma (Y) phases, and Me 2 X is an Al 2 O 3 layer, which is preferably one or both of the alpha (d) and gamma (Y) phases. The laminated multilayer has a composition gradient of metal atoms in component A, due to a change in the ratio of the average Me1X and / or Me2X layer thicknesses through the multilayer.

The coating may further comprise, on top of the laminated multilayer, at least one 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 double ("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. In the case where the metal oxide layer is produced 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 that reflects 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-PJCOCSSSGIÉ.

Example 1 An aperiodic laminated multilayer consisting of alternating metal oxide + metal oxide nanocomposite Al 2 O 3 + ZrO 2 layer and Al 2 O 3 layer, was deposited on a substrate using an RF sputtering PVD method.

Nanocomposite layer was precipitated with high purity oxide sources using different process conditions with respect to 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 zirconia stream with the intention of forming a composite material with metastable ZrO 2 phases. The power level of the sources in this case was 80 W on each oxide source. The sputtering speeds were regulated so that a twice as high% of zirconium was obtained compared to aluminum. The oxygen: metal atom ratio was 94% of the stoichiometric oxygen: metal atom ratio.

The Al 2 O 3 layer was precipitated using alumina sources in an argon atmosphere.

The sputtering times for each alternating layer were chosen to gradually increase the thickness of the Al2O3 layer against the surface of the coating.

The resulting layers were analyzed by XRD and TEM.

The X-ray diffraction analysis showed no traces of crystalline Al2O3 in the nanocomposite layer, while the Al2b layers consisted mainly of gamma Al2O3.

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 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-Al2O3 layers. The grains in the nanocomposite layer were cubic ZrO2 while the surrounding phase had a high aluminum content. The individual layer thicknesses ranged from 4 to 20 nm and the total multilayer thickness was about 1 μm. The successive increase in Al 2 O 3 layer thickness against the coating surface resulted in a Zr gradient such that the average Zr content was about 30 at-% higher, in absolute units, in the innermost region than in the outermost region of the multilayer, measured as an average Zr content over several consecutive layers in the respective areas using EDS.

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

Claims (10)

10 ß 20 25 30 35 530 945 Krav A cutting tool for metalworking, comprising a substrate of cemented carbide, cermet, ceramics, cubic boron nitride or high speed steel, for which, at least on the functional parts of 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 layers, Me1X + Me2X + Me1X + Me¿Xm, where 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, Zr and Al, more preferably Zr and Al, and wherein at least one of Me1X and Me2X is a metal oxide + metal oxide nanocomposite layer composed of two components, component A and component B, with different composition and different structure, the components of which consist of a single-phase oxide of a metal element or a solid solution of two or more metal oxides, wherein the layers Mepš and Me2X are different in composition or structure or in both of these properties and have individual layer thicknesses is greater 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 and has a composition gradient, with respect to the concentration of one or more of the metal atoms, in the direction from the outer surface of the coating against the substrate, wherein the gradient is such that the difference between the average concentration in the outermost region of the multilayer and the average concentration in the innermost region of the multilayer is at least 5 at-% in absolute units. 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, Zr, Cr, Al, Hf, Ta, Y or Si. Cutting tool according to claim 3, characterized in that one or more of the metal atoms in the at least one of the metal oxide + metal oxide nanocomposite layers is a stronger carbide or nitride former than one or more of the metal atoms in the first , inner single layer or multilayer. Cutting tool according to one of the preceding claims, characterized in that the coating further comprises, on top of the laminated multilayer, at least one outer single-layer or multilayer coating of metal carbides, metal nitrides or metal carbonitrides with a thickness of between 0.2 and 5 μm, the metal atoms being selected from one or more of Ti, Nb, V, Mo, Cr, Al, Hf, Ta, Y or Si. Cutting tool according to one of the preceding claims, characterized in that component A has an average grain size of 1 to 100 nm, preferably 1 to 70 nm, preferably 1 to 20 nm. Zr, 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. 8. A cutting tool according to any 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 (a) 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.