SE469170B - COMPOSITIVE COATINGS ON ELIGIBLE SUBSTRATE AND PROCEDURES FOR PREPARING THEREOF - Google Patents

Description

CÅ \ ¿> 10 15 ZÛ 25 30 35 40 ') 4 "? Ll' 2 hard, refractory substrate to produce an article showing improved wear resistance under extreme conditions of use.

SUMMARY OF THE INVENTION An abrasion resistant article in accordance with the invention comprises a hard, refractory substrate body and a completely dense, adhesive, abrasion resistant, composite, refractory layer on the substrate body. The composite refractory layer has at least two phases and comprises a continuous nitride layer about 0.1-2D μm thick. The nitride layer comprises at least a first refractory nitride of Si, B, Al, Y, Ti, Zr, Hf, V, Nb, Ta, Mo or W. The composite refractory layer also comprises at least one discontinuous, further phase dispersed as separate particles in the nitride layer . The further phase comprises at least one second refractory nitride of Si, B, Al, Y, Ti, Zr, Hf, V, Nb, Ta, Mo or W. The second refractory nitride is not the same as the first refractory nitride.

Another aspect of the invention includes an improvement in a method of depositing an abrasion resistant, refractory layer on a hard, refractory substrate. The process comprises passing a first gaseous mixture over the substrate, which mixture comprises a first halide vapor selected from the group consisting of halides of Si, B, Al, Y, Ti, Zr, Hf, V, Nb, Ta, Mo and W, and a or several volatile nitrous gases. The temperature is between about BÛDOC and a temperature that is harmful to the substrate properties; the pressure is between about 1 dry and ambient pressure. The process is carried out at partial pressure conditions, at a flow rate, and for a time sufficient to deposit a continuous, completely dense, adhesive, abrasion resistant layer comprising at least one refractory nitride of Si, B, Al, Y, Ti, Zr, Hf, V, Nb, Ta, Mo or W about 0.1-20 μm thick on the substrate. The improvement in the process comprises mixing the first gaseous mixture with at least one further vapor selected from the halides of Si, B, Al, Y, Ti, Zr, Hf, V, Nb, Ta, Mo and W to form a second gaseous mixture. mixture. The additional vapor is not the same as the first halogen vapor, and is mixed at a partial pressure selected to form at least one discontinuous, additional phase, dispersed as separate particles in the continuous nitride layer, and comprises at least one refractory nitride of Si, B, Al, Y, Ti, Zr, Hf, V, Nb, Ta, Mo or W to form a completely dense, adhesive, abrasion resistant, composite refractory layer on the substrate. BRIEF DESCRIPTION OF THE DRAWINGS For a better understanding of the present invention, together with the objects, advantages and possibilities thereof, reference is made to the following description and appended claims, taken in conjunction with the drawings, in which: FIG. 1 and 2 are schematic cross-sectional illustrations of substrates coated with two different process embodiments in accordance with the invention.

DETAILED DESCRIPTION OF THE INVENTION The coated articles in accordance with the present invention are prepared by depositing, by the process in accordance with the invention, an adhesive composite nitride-based coating layer having two or more phases on a hard, refractory substrate, as described above.

The co-deposition of a nitride-based composite coating with two or more phases which has the properties of adhering to the substrate, is abrasion resistant, has high temperature resistance, and resistance to chemical attack or degradation at high temperatures, depends on careful control of the process parameters. The prominent properties of the coating are a result of the embodiment with a second phase of separated particles of a nitride of Si, B, Al, Y, Ti, Zr, Hf, V, Nb, Ta, Mo or W, or a combination of these , within the matrix of a nitride of Si, B, Al, Y, Ti, Zr, Hf, V, Nb, Ta, Mo or W. Preferred coating layers comprise e.g. zirconium nitride and / or yttrium nitride particles in a continuous aluminum nitride matrix, yttrium nitride particles in a continuous zirconium nitride matrix, zirconium nitride particles in a continuous yttrium nitride matrix, titanium nitride particles in a continuous silicon nitride matrix or aluminum.

The particles can be evenly distributed in the matrix, or their distribution can be controlled to e.g. obtain a layered structure of single-phase nitride matrix parts alternating with two-phase or multiphase matrix / particle parts, preferably distributed at regulated intervals along the depth of the matrix. Similarly, the deposition can be controlled to deposit a single-phase continuous part with a controlled depth of the matrix material below the two-phase or multiphase part or the alternating single-phase / two-phase part of the coating.

The process involves the use of a mixture of gases comprising a mixture of two or more metal halides and other reaction gases under carefully controlled conditions to deposit metal compounds on a substrate by chemical vapor deposition (CVD). The metal halides are preferably prepared by passing halide gas or gases over the metals, e.g. metal particles. The metals can e.g. combined as a mixture of metals, as a metal alloy, or as metal salts. A single halide gas is passed over the combined metals to form a mixture of metal? halides. Alternatively, at least the metal forming the matrix is separate, and separate halide gas streams are passed over the metals to form separate metal halides, which are later combined. Salvage gases, e.g. Ar, can be combined with the halide gases. Preferred metal halide gases are chlorides of Si, B, Al, Y, Ti, Zr, Hf, V, Nb. These are combined with suitable other gases such as H2 and NZ or other volatile nitrate hardening gases such as NH3. One or more of the metals may advantageously be contained in a separate vessel in the CVD reactor.

In order to co-deposit a matrix with a first phase containing separated particles of a second phase or phases, it is important to control the relative deposition by controlling such parameters as gas flow rates to produce the desired co-deposition of materials with first and second phase. Normally the deposition temperature is about son-1soo ° c.

Additional control over the deposition process can be obtained by pulsing the metal halide gas forming the second phase or phases while maintaining a continuous flow of the metal halide gas forming the matrix. This pulsation method can also be used to regulate the distribution of the second phase in the matrix, e.g. to obtain either an even distribution or a layered distribution as described above.

Likewise, a single metal halide gas may be allowed to flow, with the other reaction gases, for a period of time sufficient to deposit a continuous single-phase portion of the material comprising the matrix, before the two-phase portion or alternating single-phase / two-phase or multiphase portion of the coating has been deposited.

Some examples of composite coatings in accordance with the invention are: AlN matrix / ZrN particles, ZrN matrix / YN particles, YN matrix / ZrN particles, AlN matrix / YN particles, AlN matrix / TiN -particles, AlN matrix / Zrn particles and YN particles and Si3N4 matrix / TiN particles.

The terms second phase and two phase as used herein refer to compositions comprising a continuous nitride matrix compound having a first phase and one or more additional or second phases which may be a single compound or more than one compound, in the form of discrete particles. The base mass and / or the particles may be nitrides of a single metal or a solid solution of nitrides of more than one metal, and the individual particles may be of the same or different compounds. . The particles described herein may be regularly shaped such as spheres, rods, thin fibers, etc. or irregularly shaped.

The nitrides described herein may suitably also comprise oxygen, such as oxynitrides of Si, B, Al, Y, Ti, Ar, Hf, V, Nb, Ta, Mo or W, in the first and further phases. Such oxynitrides can be obtained by including a suitable source of oxygen in the reaction gases, e.g. N0 or NO2. An example of composite refractory oxinitride coatings in accordance with the invention are: Si-Al-O-N matrix / Ti (0, N) particles.

The composite coatings in accordance with the invention are completely dense, adhesive and make it possible to combine the abrasion resistance properties of two or more components without the problems associated with the differences in coefficients of expansion and adhesion exhibited by layering continuous coatings of the materials.

The refractory coating layers described here can be combined with other refractory coating layers. For example. further improvement of the adhesion of the coating to the substrate can be achieved by depositing between the composite coating and the substrate a thin intermediate layer of TiC, TaC, Ti (C, N), or other carbide or carbonitride of Ti, Zr, Hf, V, Nb, Ta, Cr, Mo, W, Al, Si or B. Such a deposit can be achieved in a known manner as a preliminary part of the same coating process, or in a separate, previous coating process. Similarly, for special applications, e.g. for friction, appearance, abrasion or heat purposes, a thin outer layer such as TiN is applied in a known manner over the composite coating.

Figures 1 and 2, which are not to scale, schematically show typical coated articles 10 and 30 in accordance with the invention. As shown in Fig. 1, the substrate 12 is a molded, joined material of WC, and may be a cutting tool or other article that requires abrasion resistance under the extreme conditions described above. A thin layer 14 of TiC covers the substrate, at least in the area exposed to abrasion. A composite layer 16 is deposited on the TiC layer 14, and is composed of single-phase matrix portions 18 and 20 of AlN, and two-phase portions 22 of an AlN matrix 24 and spaced particles 26 of Zrn. As shown in Fig. 1, there is no division between the AlN in the two-phase portions 22 of the matrix 24 and that in the single-phase matrix portions 18 and 20.

The AlN of the composite coating is a single continuous matrix having a co-deposited second phase with controlled composition and distribution dispersed therein. An outer layer 28 of TiN is deposited on the composite layer to give 53.

O \ MO 10 15 20 25 30 35 40 178 6 article 10 a distinct, identifiable color.

Fig. 2 shows an alternative embodiment of the article in accordance with the invention. Similar features in the two figures are identified by the same reference numerals. In Fig. 2, the substrate 12 is overlaid with a thin TiC layer 14 in the same manner as shown in Fig. 1. A composite layer 32 is deposited on the Tiß layer 14 and is constituted by the AlN matrix 24 with particles 34 of YN evenly distributed through the matrix 24. An outer layer 28 of TiN is deposited on the composite layer.

The following examples are shown to enable those skilled in the art to more clearly understand and use the present invention. These examples are not to be construed as limiting the scope of the invention but merely as illustrative and representative examples of the invention.

EXAMPLE 1 After rinsing all gas lines with their respective gases for 0.5-1 hour, cutting tool inserts were coated with a cemented carbide material, steel grade C-5, with a layer of TiC, about 3 μm thick with prior art in a CVD reactor. The reactor was evacuated to about 10 torr, then heated under low pressure, while playing with liquid hydrogen, to increase degassing before deposition.

The metal halide gases were chlorides, the carrier gas for the AlCl 3 and ZrCl 4 reactions was Ar, and the nitrate curing reaction gas was NH 3 with H 2 The deposition pressure of Example 1 was about 0.75 torr; the temperature is about 1U25OC. as a carrier. The gas flow rates are shown in the table below.

The AlN deposition (one phase) was made for a period before the two-phase AlN / ZrN deposition began.

After the deposition procedure, the reactor was cooled, at the deposition pressure at the same time as it was flushed with hydrogen, to about 3ÛÛ0C, and then at ambient pressure and nitrogen flow to room temperature.

The thickness of the coatings was 4-6 mm, as measured by the abrasive ball method (Calotest) and electron microscope for scanning. The chemical composition of the coating was determined by X-ray diffraction analysis. The coating was deposited on the Tiß backing layer as a layered composition of alternating aluminum nitride and aluminum nitride / zirconium nitride parts over a single phase aluminum nitride part, similar to that shown in Fig. 1 but without the TiN layer over the nitride coating. The nitride coating and TiC backsheet show satisfactory thickness and good adhesion.

EXAMPLE 2 The procedure of Example 1 is repeated in Example 2 to coat the same type of TiC-coated, cemented carbide cutting tool inserts, except that both AlCl3 and ZrCl4 flow throughout the co-deposition period. The deposition pressure and the temperature are 100 dry and 100000, respectively. The remaining reaction conditions are given in the table below. The resulting composite coatings are similar to those shown in Fig. 2, except that no TiN layer is deposited on the nitride coating. The coating is a continuous AlN matrix with ZrN particles distributed therein. No single-phase part is deposited below the two-phase part of the nitride layer.

TABLE Flow rate cm; / min AlCl3 Zrßla Ex.

H 2 Ar NH 3 AlCl 3 ZrCl 4 flow flow 1 4300 3000 705 72 8 120 min 5 min per every 20 min Z 4300 3000 705 72 8 120 min 120 min While showing and describing what are currently considered to be the preferred embodiments of the invention, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention as defined in the appended claims.

Claims (21)

4 Å U 10 15 20 25 30 35 40 ... A »J to PATENTKRAV Abrasion resistant article comprising a hard, refractory substrate body (12) and a completely dense, adhesive, abrasion resistant composite refractory layer (16, 32) on the substrate body, wherein the composite refractory layer is characterized by: (18, 20 , 24) which is about 0.1-20 μm thick and which comprises at least a first refractory nitride of Si, B, Al, Y, Ti, Hf, V, Nb, Ta, Mo or W; at least two phases, a continuous nitride layer Zr, and at least one discontinuous further phase dispersed as separated particles (26, 34) in the nitride layer, and comprising at least one second refractory nitride of si, B, A1, Y, Ti, zr, Hf , v, Nb, Ta, Mo or W; where the second refractory nitride is not the same as the first refractory nitride; and a thin intermediate layer selected from the group consisting of carbides or carbonitrides of Ti, Hf, V, Nb, Cr, Zr, Ta, Mo, W, Al, Si and B, between the substrate and the refractory nitride layer. Article according to claim 1, characterized in that the further phase (26, in the continuous nitride layer (13, 34) is substantially evenly dispersed (20, 24). characterized in that the non-refractory layer is a layered layer in which Article according to claim 1, manned, parts with at least two phases alternate with single-phase continuous nitride parts. Article first refractory according to claim 1, characterized in that that nitride is AlN and that the second refractory nitride is ZrN. Article according to claim 1, characterized in that the first refractory nitride is ZrN and that the second refractory nitride is YN. Article first refractory according to claim 1, characterized in that that nitride is YN and that the second refractory nitride is ZrN. Article first refractory according to claim 1, characterized in that that nitride is Si 3 N 4 and that the second refractory nitride is TiN. 10 15 20 25 30 35 40 7 * fä ”WH 4130 i; .1 Article according to claim 1, characterized in that the first refractory nitride is AlN and that the second refractory nitride is TiN. Article according to claim 1, characterized in that at least one further phase comprises at least the second refractory nitride and at least a third refractory nitride of Si, B, Al, Y, Ti, Zr, Hf, V, Nb, Ta , Mo or W. Article according to claim 9, the first refractory nitride is AlN, characterized in that the second refractory nitride is ZrN, and that the third refractory nitride is YN. 11. ll. A method of depositing an abrasion resistant refractory layer on a hard refractory substrate comprising the steps of: passing over the substrate a first gas mixture comprising a first halide vapor selected from the group consisting of halides of Si, B, Al, Y, Ti, Zr , Hf, V, Nb, Ta, Mo and W, and one or more volatile nitrate-curing gases, at a temperature between about 800 ° C and a temperature that is harmful to the substrate properties, at a pressure between about 1 dry and about ambient pressure , and at partial pressure conditions, flow rate and for a period of time sufficient to deposit a continuous, completely dense, adhesive, abrasion resistant layer comprising at least one refractory nitride of Si, B, Al, Y, Ti, Zr, Hf , V, Nb, Ta, Mo or W about 0.1-20 μm thick on the substrate; characterized by the steps of: mixing with the first gas mixture at least one additional steam selected from the halides of Si, B, Al, Y, Ti, Hf, V, Nb, Mo and W to form a second gas mixture; Zr, Ta, where the additional vapor is not the same as the first halide vapor, and is mixed at a partial pressure selected to form at least one discontinuous, additional phase, dispersed as discrete particles in the continuous nitride layer, and comprising at least a refractory nitride of Si, B, Al, Y, Ti, Hf, V, Nb, Ta, Mo or W to form a completely dense, adhesive, abrasion resistant, Zr, composite refractory layer on the substrate; and t; '\ \ .. J 10 15 20 25 30 35 40., - .. \ ~ a <, ::> / 0 that a thin intermediate layer selected from the group consisting of carbides or carbonitrides is deposited between the substrate and the refractory nitride layer. of Ti, Zr, Hf, Va, Nb, Ta, Cr, Mo, W, Al, Si and B. A process according to claim 11, the first gas mixture containing NO or NO 2; and characterized in that the composite refractory layer is a continuous first phase of at least one refractory oxynitride of Si, B, Al, Y, Ti, Zr, Hf, V, Nb, Ta, Mo or W with separated pairs dispersed therein. articles comprising at least one refractory oxynitride of Si, B, Al, Y, Ti, Hf, V, Nb, Mo or W. A method according to claim 11, characterized in that the step of mixing at least one further steam with the first gas mixture comprises intermittently pulsing the at least additional steam into the first gas mixture. 14. the first gas mixture contains NO or NO 2; and the co-Process according to claim 13, characterized in that the manned refractory layer is a continuous first phase of at least one refractory oxynitride of Si, B, Al, Y, Ti, Zr, Hf, V, Nb, Ta, Mo or W with separate particles dispersed therein comprising at least one refractory oxynitride of Si, B, Al, Y, Ti, Hf, V, Nb, Ta, Mo or W. A method according to claim 13, Zr, characterized by the step of controlling the size and distribution in the nitride layer with the further phase particles by controlling the partial pressure, the time intervals and the lengths of time at which at least one further steam is pulsed into the first gas mixture. A method according to claim 15, characterized in that the deposition step of the continuous nitride layer is performed for a sufficient time before the pulsation step is started to form a single-phase, continuous nitride part which separates the substrate and two or more phase parts of the composite ceramic coating. The intermittent pulsing step takes place at time intervals and Method according to claim 15, characterized in that during time periods selected to form a layered, composite, ceramic layer in which two or more phase parts alternate with single-phase, continuous nitrite parts. Method according to claim 11, characterized in that the If ¿C f: ~ ø u 'F; | I D r_- O \ - | The second gas mixture is N2 or NH3, hydrogen and chlorides of two of Al, Zr and Y; and that the composite refractory layer is a continuous first phase of AlN with separated particles of ZrN dispersed therein, or a continuous first phase of ZrN with separated particles of YN dispersed therein, or a continuous first phase of YN with separated particles of ZrN dispersed therein . The second gas mixture is N2 or NH3, hydrogen, and chlorides of The process according to claim 11, characterized in that it is Si and Ti; and that the composite refractory layer is a continuous first phase of Si3N4 with separate particles of TiN dispersed therein. The second gas mixture is Ng or NH 3, hydrogen, and chlorides of Process according to claim 11, characterized in that it Al and Ti; and that the composite refractory layer is a continuous first phase of AlN with separated particles of TiN dispersed therein. The second gas mixture is NO or NO 2, hydrogen, and chlorides of Process according to claim 12, characterized in that it is silicon and aluminum; and that the composite refractory layer is a continuous first phase of silicon aluminum oxynitride with separate particles of Ti (0, N) dispersed therein.