ARTICLES CONSISTING OF METAL, HARD METAL, CERMET OR CERAMIC AND COATED WITH A HARD MATERIAL, AND METHOD FOR PRODUCING SUCH ARTICLES

Abstract

Articles containing metal, hard metal, cermet or ceramic and coated with a hard material, and a method for producing same. The hard material layers can be used as anti-wear layers for cutting tools, as protective layers for turbine blades, or as diffusion barriers in microelectronics. The hard material layers exhibit a high hardness, high oxidation resistance, and excellent wear resistance. The articles are coated with a single- or multi-layer layer system by a thermal CVD method without plasma excitation, where the single- or multi-layer layer system includes at least one nanocomposite layer with a first nanocrystalline phase of cubic titanium oxycarbonitride and a second, amorphous phase of silicon oxycarbonitride or silicon oxycarbide.

Claims

1. Articles consisting of metal, hard metal, cermet or ceramic and coated with a hard material, which articles are coated with a single- or multi-layer layer system by a thermal CVD method without plasma excitation, wherein the single- or multi-layer layer system contains at least one nanocomposite layer with an overall composition of (Ti.sub.xSi.sub.y)(C.sub.aN.sub.bO.sub.c) with 0.7<x0.99 and 0.01y<0.3 and 0.4<a<0.9 and 0.1<b<0.6 and 0.01<c0.1, wherein the nanocomposite layer comprises a first nanocrystalline phase of cubic titanium oxycarbonitride with a crystallite size of 10 nm to 100 nm and a second, amorphous phase of silicon oxycarbonitride or silicon oxycarbide, and wherein the nanocomposite layer has a chlorine content between 0.001 and 1 at. %.

2. The articles coated with a hard material according to claim 1 in which multiple nanocomposite layers are arranged.

3. The articles coated with a hard material according to claim 1 in which the one or more nanocomposite layers have a gradient with respect to the Si/Ti atomic ratio.

4. The articles coated with a hard material according to claim 1 in which at least one nanocomposite layer has a lamellar structure.

5. The articles coated with a hard material according to claim 4 in which the layer having the lamellar structure comprises lamellae with a thickness between 50 nm and 500 nm.

6. The articles coated with a hard material according to claim 4 in which the layer having the lamellar structure comprises lamellae with different Si/Ti atomic ratios.

7. The articles coated with a hard material according to claim 1 in which the nanocomposite layer has a hardness of 3000 HV to 4000 HV, advantageously a hardness of 3300 HV to 3600 HV.

8. The articles coated with a hard material according to claim 1 in which the nanocrystalline phase has a crystallite size of 10 nm to 20 nm.

9. The articles coated with a hard material according to claim 1 in which the nanocomposite layer has a layer thickness of 1 m to 10 m, advantageously a layer thickness of 4 m to 7 m.

10. The articles coated with a hard material according to claim 1 in which one or more cover layers and/or bonding layers are present.

11. The articles coated with a hard material according to claim 10 in which the cover layers and/or bonding layers are composed of one or more nitrides, carbides, carbonitrides, oxynitrides, oxycarbides, oxycarbonitrides, oxides of Ti, Hf, Zr, Cr and/or Al or mixed phases of these elements.

12. A method for producing articles consisting of metal, hard metal, cermet or ceramic and coated with a hard material, comprising: at least one (TixSiy)(CaNbOc) nanocomposite layer is deposited by a thermal CVD method without plasma excitation in a gas mixture of TiCl.sub.4, one or more silicon chlorides, CH.sub.3CN, H.sub.2, CO and/or CO.sub.2 and at temperatures between 700 C. and 950 C. and at pressures between 0.1 kPa and 0.1 MPa, wherein an Si/Ti atomic ratio of greater than 1 is chosen for the silicon chloride and titanium chloride in the gas phase.

13. The method according to claim 12 in which N.sub.2 is added to the gas mixture.

Description

[0043] The invention is explained below in greater detail with the aid of exemplary embodiments and figures. The figures show:

[0044] FIG. 1: An X-ray diffractogram of the (Ti.sub.xSi.sub.y)(C.sub.aN.sub.bO.sub.c) nanocomposite layer according to Exemplary Embodiment 1 produced by means of a CVD method without plasma excitation;

[0045] FIG. 2: An XPS spectrum with a resolved Si2p peak for the (Ti.sub.xSi.sub.y)(C.sub.aN.sub.bO.sub.c) nanocomposite layer in Exemplary Embodiment 1;

[0046] FIG. 3: An X-ray diffractogram of the (Ti.sub.xSi.sub.y)(C.sub.aN.sub.bO.sub.c) nanocomposite layer according to Exemplary Embodiment 2 produced by means of a CVD method;

[0047] FIG. 4: An XPS spectrum with an O1s peak for the (Ti.sub.xSi.sub.y)(C.sub.aN.sub.bO.sub.c) nanocomposite layer in Exemplary Embodiment 2;

[0048] FIG. 5: A TEM micrograph of the (Ti.sub.xSi.sub.y)(C.sub.aN.sub.bO.sub.c) nanocomposite layer (B) with a lamellar structure and the TiN layer (A) positioned thereunder according to Exemplary Embodiment 3;

[0049] FIG. 6: An XPS spectrum with a resolved Si2p peak for the (Ti.sub.xSi.sub.y)(C.sub.aN.sub.bO.sub.c) nanocomposite layer in Exemplary Embodiment 4;

EXEMPLARY EMBODIMENT 1

[0050] A high-silicon (Ti.sub.xSi.sub.y)(C.sub.aN.sub.bO.sub.c) nanocomposite layer is deposited as a cover layer by means of a thermal CVD method on WC/Co indexable hard metal inserts that are pre-coated with a 5-m thick TiN/TiCN/TiN layer system. The coating process is carried out in a hot wall CVD reactor with an inner diameter of 75 mm. The CVD coating takes place with a gas mixture of 0.09 vol. % TiCl.sub.4, 0.58 vol. % SiCl.sub.4, 0.23 vol. % CH.sub.3CN, 0.31 vol. % CO and 98.79 vol. % H.sub.2. The deposition temperature is 850 C. and the process pressure is 6 kPa. After a coating time of 90 min, a 4.5-m thick (Ti.sub.xSi.sub.y)(C.sub.aN.sub.bO.sub.c) layer is obtained.

[0051] From the X-ray diffractogram in FIG. 1, it is evident that only a cubic TiC.sub.1N.sub.1-x phase is identified in the X-ray thin layer analysis conducted with grazing incidence. XPS analyses found that the cubic TiC.sub.CN.sub.1-x phase is composed of titanium oxycarbonitride. The O1s spectrum has a broad peak between 529 and 533 eV, which can be attributed both to TiO and also SiO bonds. As an additional phase, the nanocomposite layer contains amorphous silicon oxycarbonitride, which was identified by the XPS analysis shown in FIG. 2.

[0052] By means of Rietveld analysis, a crystallite size of 18.31.8 nm was determined for the nanocrystalline titanium oxycarbonitride phase.

[0053] The elemental analysis by means of WDX found the following element content:

[0054] 39.5 at. % Ti,

[0055] 9.7 at. % Si,

[0056] 27.2 at. % C,

[0057] 21.0 at. % N,

[0058] 2.1 at. % O,

[0059] and 0.5 at. % Cl.

[0060] For this (Ti.sub.xSi.sub.y)(C.sub.aN.sub.bO.sub.c) nanocomposite layer, there results a y value of 0.2, which is calculated from the concentrations in at. % in accordance with y=Si/(Si+Ti). From the WDX elemental analysis, there results an overall composition for C, N, O with a=0.54, b=0.42 and c=0.04. By means of a Vickers indenter, a microhardness of 3590 HV [0.01] was measured.

Exemplary Embodiment 2

[0061] A low-silicon (Ti.sub.xSi.sub.y)(C.sub.aN.sub.bO.sub.c) nanocomposite layer is deposited as a cover layer by means of a thermal CVD method on WC/Co indexable hard metal inserts that are pre-coated with a 5-m thick TiN/TiCN/TiN layer system. The coating process is carried out in a hot wall CVD reactor with an inner diameter of 75 mm. The CVD coating takes place with a gas mixture of 0.18 vol. % TiCl.sub.4, 0.57 vol. % SiCl.sub.4, 0.22 vol. % CH.sub.3CN, 0.78 vol. % CO, 71.38 vol. % H.sub.2, and 26.87 vol. % N.sub.2. The deposition temperature is 850 C. and the process pressure is 6 kPa. After a coating time of 90 min, a 6.9-m thick (Ti.sub.xSi.sub.y)(C.sub.aN.sub.bO.sub.c) layer is obtained.

[0062] In the X-ray thin layer analysis conducted with grazing incidence, only a cubic TiC.sub.xN.sub.1-x phase is identified, as the X-ray diffractogram presented in FIG. 3 shows. XPS analyses found that the cubic TiC.sub.xN.sub.1-x phase is composed of titanium oxycarbonitride. According to FIG. 4, the O1s spectrum has a broad peak between 529 and 533 eV, which can mainly be attributed to TiO bonds due to the low silicon content of the layer, but also to TiNO and/or TiCO bonds.

[0063] As an additional phase, the nanocomposite layer contains amorphous silicon oxycarbonitride, which was also identified by means of XPS analysis. By means of Rietveld analysis, a crystallite size of 16.82.1 nm was determined for the nanocrystalline titanium oxycarbonitride phase.

[0064] The elemental analysis by means of WDX found the following element content:

[0065] 43.2 at. % Ti,

[0066] 1.7 at. % Si,

[0067] 26.0 at. % C,

[0068] 25.4 at. % N,

[0069] 3.4 at. % O, and

[0070] 0.3 at. % Cl.

[0071] For this (Ti.sub.xSi.sub.y)(C.sub.aN.sub.bO.sub.c) nanocomposite layer, there results a y value of 0.04, which is calculated from the concentrations in at. % in accordance with y=Si/(Si+Ti). From the WDX elemental analysis, there results an overall composition for C, N, O with a=0.47, for b=0.46 and for c=0.06. By means of a Vickers indenter, a microhardness of 3330 HV [0.01] was measured.

Exemplary Embodiment 3

[0072] A (Ti.sub.xSi.sub.y)(C.sub.aN.sub.bO.sub.c) nanocomposite layer is deposited as a cover layer by means of the thermal CVD method according to the invention on WC/Co indexable hard metal inserts that are pre-coated with a 5-m thick TiN/TiCN/TiN layer system. The coating process is carried out in a hot wall CVD reactor with an inner diameter of 75 mm. The CVD coating takes place with a gas mixture of 0.09 vol. % TiCl.sub.4, 0.58 vol. % SiCl.sub.4, 0.22 vol. % CH.sub.3CN, 0.31 vol. % CO, 71.5 vol. % H.sub.2, and 27.3 vol. % N.sub.2. The deposition temperature is 850 C. and the process pressure is 6 kPa.

[0073] After a coating time of 90 min, a 4.1-m thick (Ti.sub.xSi.sub.y)(C.sub.aN.sub.bO.sub.c) nanocomposite layer is obtained.

[0074] FIG. 5 shows a TEM micrograph of a cross-section of a (Ti.sub.xSi.sub.y)(C.sub.aN.sub.bO.sub.c) nanocomposite layer that has a lamellar structure which is produced with an SiCl.sub.4/TiCl.sub.4 ratio set between 4 and 7. Different Si/Ti atomic ratios are present in the lamellae, which ratios can be identified by an EDX line scan. In the X-ray thin layer analysis conducted with grazing incidence, only a cubic TiC.sub.xN.sub.1-x phase is identified. Silicon is contained in a second, amorphous silicon oxycarbonitride phase. By means of Rietveld analysis, a crystallite size of 17.02.7 nm was determined for the nanocrystalline titanium oxycarbonitride phase.

[0075] The elemental analysis by means of WDX found the following element content:

[0076] 42.1 at. % Ti,

[0077] 4.7 at. % Si,

[0078] 26.7 at. % C,

[0079] 23.7 at. % N,

[0080] 2.7 at. % O, and

[0081] 0.1 at. % Cl.

[0082] For this (Ti.sub.xSi.sub.y)(C.sub.aN.sub.bO.sub.c) nanocomposite layer, there results a y value of 0.1, which is calculated from the concentrations in at % in accordance with y=Si/(Si+Ti). From the WDX elemental analysis, there results an overall composition for C, N, O with a=0.50, for b=0.45 and for c=0.05. By means of a Vickers indenter, a microhardness of 3410 HV [0.01] was measured.

Exemplary Embodiment 4

[0083] A (Ti.sub.xSi.sub.y)(C.sub.aN.sub.bO.sub.c) nanocomposite layer is deposited as a cover layer by means of a thermal CVD method on WC/Co indexable hard metal inserts that are pre-coated with a 5-m thick TiN/TiCN/TiN layer system. The coating process is carried out in a hot wall CVD reactor with an inner diameter of 75 mm. The CVD coating takes place with a gas mixture of 0.12 vol. % TiCl.sub.4, 0.58 vol. % SiCl.sub.4, 0.22 vol. % CH.sub.3CN, 0.59 vol. % CO, 71.36 vol. % H.sub.2, and 27.13 vol. % N.sub.2. The deposition temperature is 850 C. and the process pressure is 6 kPa. After a coating time of 90 min, a 4.4-m thick (Ti.sub.xSi.sub.y)(C.sub.aN.sub.bO.sub.c) layer is obtained.

[0084] In the X-ray thin layer analysis conducted with grazing incidence, only a cubic TiC.sub.xN.sub.1-x phase is identified. XPS analyses found that the cubic TiC.sub.xN.sub.1-x phase is composed of titanium oxycarbonitride. As an additional phase, the nanocomposite layer contains amorphous silicon oxycarbide that was identified by the XPS analysis shown in FIG. 6. By means of Rietveld analysis, a crystallite size of 14.02.1 nm was determined for the nanocrystalline titanium oxycarbonitride phase.

[0085] The elemental analysis by means of WDX found the following element content:

[0086] 42.5 at. % Ti,

[0087] 2.7 at. % Si,

[0088] 25.5 at. % C,

[0089] 26.2 at. % N,

[0090] 2.9 at. % O, and

[0091] 0.2 at. % Cl.

[0092] For this (Ti.sub.xSi.sub.y)(C.sub.aN.sub.bO.sub.c) nanocomposite layer, there results a y value of 0.06, which is calculated from the concentrations in at % in accordance with y=Si/(Si+Ti). From the WDX elemental analysis, there results an overall composition for C, N, O with a=0.47, for b=0.48 and for c=0.05. By means of a Vickers indenter, a microhardness of 3410 HV [0.01] was measured.