Title of Invention

COATED SUBSTRATE BODY AND A METHOD FOR ITS MANUFACTURE

Abstract

Disclosed herein is an invention concerning a coated substrate body made of a composite material and a method for its manufacture, on which a single - or multiple - layered coating of at least a 0.5 pm to 25 pm thick layer contains an A1<sub>2</sub>O<sub>3</sub> phase and ZrO<sub>2</sub> phase. According to the invention, in this A1<sub>2</sub>O<sub>3</sub> / ZrO<sub>2</sub> layer, a third, finely-dispersed phase can be deposited, which consists of an oxide, oxy-carbide, oxy-nitride or oxycarbonitride of titanium. For this, a CVD method is used, with deposition temperatures of between 900 deg. C and 1000 deg. C in the gas phase under pressures of 10 to 10000 Pa, whereby the gas phase contains, besides the necessary gases, 0.2 to 2 mol-% TiC1<sub>4</sub>.

Full Text

The invention relates to a coated substrate body selected from the group, which consists of hard metal or cermet, having either a single layer, or a multi - layered coating, the coating thickness is at least a 0.5 micron- to 25 micron-thick layer, preferably the outer¬most layer, contains an Al2 O3 phase and a ZrO; phase. The invention concerns further with a method for the manufacture of a layer containing an Al2 O3 phase and a ZrO2 phase on a substrate body, through a CVD (Chemical Vapour Deposition) method with-deposition temperature of between 900 deg. C and 1000 deg. C in the gas phase, which contains gases of the AlCl3, ZrCl4, CO2, H2, CH4 and N2 group or inert gases which are necessary for the deposition, and under pressures of from 10 to 100,000 Pa. Already, in DE 27 36 982 Al is described a wear-resistant layer for formed parts, especialiy tools, made of a formed body, preferably made of hard metal, and one or more surface layers, which consists at least one protective layer made of a ceramic matrix, in which a further material is deposited. The Ceramic matrix and the deposited material possess clearly thermal expansion coefficients different from each other so that the fine micro-cracks pass through the protective layer. Unstabilised and/or partly stabilised ZrO2 is suggested as coating material in a ceramic matrix made of AI2 O3. For the production of one such layer as per the CVD method, aluminium trichloride, carbon dioxide and hydrogen in the gas phase for the formation of Al2 O3, as well as zirconium tetrachloride and water vapour for the formation of ZrO; are introduced in a reaction vessel at 1100 deg. C. Due to the density difference between the tetragonal modification of the zirconium oxide remaining above a transformation temperature of about 1100 deg. C and the monoclinic modification of the zirconium oxide remaining below a transformation temperature of about 1100 deg. C, an increasing volume change of the coated zirconium oxide with a corresponding phase fransformation results. From this, it follows that with increasing volume division of zirconium oxide, there is simultaneous increase in the micro-crack thickness of the deposited ceramic layer. A hard metal body with a thin wear-resistant surface layer made of aluminium oxide is described in DE 28 25 009 C2, which is made up totally or at least 85% of the K-modification, and which forms an eventual balance portion consisting of the α-modification on the surfaces, places or regions, with a dimension of maximum 10 µm. The aluminium oxide layer can, in addition, contain additions of titanium, zirconium and/or hafnium. For the manufacture of this ceramic coating by the CVD method, the gas mixture besides H2, AlCl3, CO2 and CO are added m small quantities of 0.03 to 0.5%Ticl4. This addition serves however exclusively, or almost exclusively, for the formation of the - aluminium oxide phase. Another CVD method for the deposition of Al2 O3 and/or ZrO2 under the application of an additional reagent like hydrogen sulphide is described in EP O 523 021 Bl. De 195 18 927 Al describes a coated cutting tool, consisting of a smtered carbide or ceramic substrate with a wear-resistant compound ceramic protective layer, which has two different metal oxide phases made of e.g., Al2 O3 and Z, O2, as well as a doping medium, which is selected from the sulphur, selenium, tellurium, phosphorus, arsenic, antimony and bismuth groups, or the compounds of the elements mentioned. For the production of these two-phase coatings as per a CVD method, as an example, aluminium and zirconium chloride, carbon dioxide with hydrogen as carrier besides a H2 S gas is passed over the substrate body at a temperature of about 700 to 1250 deg. C and at a pressure of 133 Pa upto atmospheric pressure, whereby, the two-phased layer is deposited with the doping material. The purpose of the present invention is to improve the wear resistance of the composite material mentioned in the beginning. Especially with the application of this composite material for cuttmg units for metal cuttmg work, improvements m the tool life and the cutting efficiency are desirable. Further, it is also the aim of the present invention, to offer a manufacturing method for the unproved composite material. The purpose is achieved by the coated substrate body, which, according to the invention, is thus characterised in that, in the layer containing Al2 O3 and ZrO2, and a third finely dispersed phase is deposited, which contains an oxide, oxy-carbide, oxy-nitride or oxy-carbonitride of titanium. Especially, the third phase can contain TiO2, TiO, Ti2 O, Ti2 O3, Ti (O, C), Ti (0,N) or Ti (0,C,N) or mixed phases thereof, which will be indicated in the following as TiOx phase in general. The deposition of TiOx compounds in the two-phase ceramic layer is aimed advantageously at a dispersion-solidifying operation, which markedly improves the wear-resistance of this layer. As per a special version of the mvention, the proportion of this third phase (TiOx) in the total volume of the ceramic layer amounts to 0.2, preferably 0.6, to 5 mol-%, further preferably at least 1 mol-%. The mol ratio of the Al2 O3 phase to the ZrO2 phase is adjusted according to requirement, i.e., depending on the purpose of application of the compound material. It is generally well known that aluminium oxide has a high hardness and a low thermal conductivity at 1000 deg. C. The heat originating from the use of the composite material as cutting unit during machining is thus conducted mainly into the chip and only to a small duration into the cutting unit, which reduces the danger of plastic deformation of the cutting edges. At higher termperatures, aluminium oxide is also oxidation-resistant, and the wear rate with ferrous workpieces as well as the friction coefficient are small. However, in the case of deposition of pure Al2O3 layers, the problem remains, of controlling the grain growth during deposition, only with difficulty. The ZrO2, which likewise is highly resistant against chemical reaction and has a remarkably low friction coefficient against ferrous materials, is, on the contrary, lighter than the Al2O3, and has however the advantage that, during total deposition with Al2 O3, it reduces the crystal growth of Al2O3 phase and also the friction coefficients in the compound. According to the purpose of the application, during which the improved chemical inertness of ZrO2 or the higher wear resistance of Al2O3 against wear should be used, the appropriate ratio of both the phases is selected. Preferably, the ratio of Al2 O3 phase to the ZrO2 phase lies between 9/10 and 10/1, whereby the ZrO2 can remain in monoclinic and/or tetragonal form. The third phase, a fine-crystalline phase, as per another version of the invention, has crystals of sizes smaller than 1/100th of the size of the crystals of the Al2 O3 and ZrO2 phases. As per another version of the invention, the compound material layer is multi-layered and has at least one layer made of carbide, nitride or carbonitride of one of the elements of the IVa to Via groups of the Periodic Table. Here, especially as intermediate layer between the basic body and the outer layer made of Al2 O3 / ZrO2 / TiOx, a layer made of TiN and/or Ti (C, N) is proposed. There is elimination of the danger of chipping off of the relatively brittle ceramic coating from the basic body. The thickness of the Al2 O3 / ZrO2/ TiOx layer lies preferably between 1 ym and 10 µm, especially between 2 µm and 8 µm. The total thickness of the coating shall not exceed 20 µm. In a special version of the invention, the first layer deposited on the basic body and made of a titanium nitride or titanium carbonitride has a thickness of between 3 and 8 µm, and the second layer consisting of Al2 O3 / ZrO2 / TiOx a thickness of between 2 and 8 µm, whereby this second layer is either the outer layer, or, whereby, on this second layer, an outer layer made of TiN, ZRO2 or ZrCN having a thickness of between 1 and 5 µm is deposited. For the production of the Al2 O3 - ZrO2 - TiOx layer described above, according to the invention, the method as per claim 9 is proposed. For the CVD coating, coating temperatures of between 900 deg. C. and 1000 deg. C are selected. Possibly, 900 deg. C can be rarely lowered due to the very low deposition rates, like the deposition temperatures of 1000 deg. C which cannot be exceeded, since at higher temperatures, too thick depositions are encountered in the region of the edges of the composite material, which leads to unintentional separations (crumblmgs), especially during the application of the composite material as cutting units. The pressure in the gaseous atmosphere, which consists of AICI3, ZrCl4, CO2, H2, CH4 and N2 or inert gases, amounts to 10 to 10000 Pa. According to the invention, the gas phase contains 0.2 to 2 mol-% TiCl4. With the exception of the portion of titanium chloride in the gas phase, the CVD method is basically well-known as per the state-of-the-art, e.g. as per DE 195 18 927 Al cited in the beginning. As per a further version of the invention, the proportions of the gas phase of AlCl3 amounts to 1 to 5 mol-% and/or the gas phase proportion of ZrCl4, 0.2 to 5 mol-%, in order to achieve the desired the relative percentage of the portions of the Al2 O3 phase to the ZrO2 phase. Preferably, the gas phase pressure lies below 10000 Pa, especially around 8000 Pa. For the deposition of a multi-layered coating on a hard metal basic body, which possessed a composition 94 m-% WC, rest Co, a CVD method with a temperature of gas phase of 1000 deg. C is selected. The pressure of the corresponding gas phase lay around 8000 Pa. In a first version example of the mvention, a layer series of TiN, Ti (C,N)and the Al2O3 / ZrO2 I TiOx outer layer described above was coated. The individual layer thickness as well as the gases used can be taken as per the following table: Total thickness 14.2 The composition of the gas phase during the deposition of the outer layer consisted of 10.1 of AICI3, 2.5 1 of ZrCU, 1.6 1 of TiCL,, 20 1 of CO2, 40 1 of N2, 320 1 of H2 and 15 1 of CH4. The layer structure is shown in Fig. 1 of the accompanying drawings which shows an X-ray structural photograph. As can be seen especially in the magnified X-ray Structural photograph of the outer layer (Fig. 2), the outer layer possessed the Al2 O3 portions appearing as dark phases, the ZrO2 portions appearing bright phase, as well as the TiOx phase appearing as white points. This phase has a crystal size which is less than 1/100th ofthe crystal size ofboth the other phases made of Al2O3 and ZrO2 . Compared to this, over a substrate body which had a composition of 94 m-% WC, 6 m-% Co, the layer series was deposited as follows: Total thickness 13.8 Our such layer series with an Al2 O3 outer layer is well-known as per the state-of-the-art. The compound bodies as per this type in the form of throw-away inserts with a SNUN 120412 geometry corresponding to the layer composition as per the Table above have been used for turning of a shaft made of greay cast iron Grade GG25 under the following cutting conditions: With the throw-away inserts known as per the state-of-the-art, which have an Al2 O3 outer layer, tool lives of about 4 minutes could be achieved on an average. The throw-away insert coated according to the invention with an Al2 O3 / ZrO2 / TiOx outer layer reached, on the other hand, under the cutting conditions mentioned above, tool lives of 13.7 minutes. This clarifies that the cutting unit as per the invention has a highly improved wear resistance. In another application example, throw-away inserts with a coating as per the state-of-the-art and with a coating according to the invention were used for milling. The cutting units had the geometry RDMW 1605. The substrate body used here, however, was a hard metal body with 94 m-% WC and 6 m-% Co. The individual layers known as per the state-of-the art were as follows; Total thickness 6.6 The coating according to the invention was deposited under a gas phase temperature of 980 deg. C as follows: Total thickness 6.7 Here, additionally, N2 is introduced in a quantity of 20 1 in the gas phase. The series of throw-away inserts manufactured in a version type known as per the state-of-the-art with an outer layer of Al2 O3, as well as a series of throw-away inserts with a coating as per the invention have been used for the plain milling of a workpiece made of 56NiCrMoV7 having a strength of 1300 N/min2, with the following cutting conditions: The tool life per blade attainable by cutting units known as per the state-of-the-art amounted to 4000 mm on an average, while the inserts according to the invention could reach an average life of 13000 mm. Also, in this case, more than three times higher stability could be obtained. Instead of hard metal basic body, ceramics of known composition can also be used. Likewise, for special applications, an additional top layer of ZrCN and/or ZrO2 or TiN can be deposited on the ceramic outer layer as per the invention. As long as the basic body is built as cutting units, these are useful for turning, milting and especially high-speed milling. WE CLAIM 1. A coated substrate body selected from the group which consists of hard metal or cermet having a coating formed by at least one layer and having a coating thickness of 0.5µm to 25 µm, the coating comprising a three-phase layer containing an Al2 O3 phase and a second phase selected from the group which consists of ZrO2, and mixtures of ZrO2 and a third finely dispersed phase embedded in said three-phase layer consisting of at least one compound selected from the group which consists of an oxide, oxycarbide, oxynitride and oxycarbonitride of titanium, and the third finely dispersed phase consisting of individual crystallites of a size which is smaller than 1/100 of the crystallite size of the Al2O3 phase and the second phase. 2. The coated substrate body as claimed in claim 1, wherein third phase consists of TiO2, TiO, Ti2O, Ti2O3, Ti(O, C), Ti(O, N) or Ti(O, C, N) or mixed phases thereof 3. The coated substrate body according to claim 2, wherein a molar percent ratio of the third phase in relation to the total amount of said at least one layer is 0.2 preferably 0.6 to 5 mol %, and the mol ratio of the Al2O3 phase to the second phase lies between 9/10 and 10/1, whereby the second phase consists of at least one of the compounds ZrO2, present in a monoclinic or tetragonal form. 4. The coated substrate body as claimed in claim 3, wherein the molar percent ratio of the third phase in said layer containing said third phase is at least one mole %. 5. The coated substrate body as claimed in claim 3, wherein the coating is multilayered and contains at least one other layer consisting of a carbide, nitride, carbonitride or of an element of the Groups IVa to VIa of the classification of elements. 6. The coated substrate body as claimed in claim 5, wherein a first layer deposited on the substrate body has a thickness between 3 µm and 8 µm and a second layer consisting of Al2O3 /ZrO2/TiOx, has a thickness between 2 µm and 8µm whereby this second layer is either the outer layer or whereby on this second layer an outer coating of TiN, ZrOj, or ZrCN with a thickness between l^mi and 5|im is deposited. 7. The coated substrate body as claimed in claim 5, wherein a layer sequence deposited on the substrate body consists of a layer of TiN or Ti {C, N) and an outer layer of consisting of said three-phase layer wherein the compound of titanium is TiO2, TiO, Ti2O, Ti2O3, Ti (O, C), Ti(0, N) or Ti(0, C, N) or mixed phases thereof. 8. The coated substrate body as claimed in claim 7, wherein the thickness of the three-phase layer ranges between 1 µm and 10 µm and that the total thickness of the coating does not surpass 25 µm. 9. A Method for the coating of a layer, consisting of an Al2 O3 phase and a ZrO; phase on a substrate body as claimed in claims 1 to 8 through a CVD (Chemical Vapour Deposition) method, with deposition temperatures of between 900 deg. C and 1000 deg. C in the gas phase, which contams the gases necessary for the deposition, these gases being from the AlCl3, ZrCl4, CO2, H2, CH4, and N2 groups or mert gases, and under pressure of between 10 and 10000 Pa, characterised in that, the gas phase contains 0.2 to 2 mol-% TiCl4. 10. The Method as claimed in claim 9, wherem, the gas phase portion of the AlCl3 amounts to between 1 to 5 mol-%, and/or the gas phase portion of the ZrCl4 amounts to between 0.2 and 5 mol-%. 11. The Method as claimed in claim 9 or 10, wherein, the gas phase pressure is less than 10000 Pa, preferably lies around 8000 Pa.

Documents:

0061-mas-1999 abstract.pdf

0061-mas-1999 claims duplicate.pdf

0061-mas-1999 claims.pdf

0061-mas-1999 correspondence others.pdf

0061-mas-1999 correspondence po.pdf

0061-mas-1999 description (complete) duplicate.pdf

0061-mas-1999 description (complete).pdf

0061-mas-1999 drawings.pdf

0061-mas-1999 form-1.pdf

0061-mas-1999 form-19.pdf

0061-mas-1999 form-26.pdf

0061-mas-1999 form-3.pdf

0061-mas-1999 form-4.pdf

0061-mas-1999 pct search report.pdf

0061-mas-1999 pct.pdf

0061-mas-1999 petition.pdf

61-MAS-1999 FORM-13 05-07-2011.pdf

61-MAS-1999 CORRESPONDENCE OTHERS 05-07-2011.pdf