Decorative HIPIMS hard material layers

Abstract

A method for coating substrates with a decorative layer of hard material which is guided into a vacuum coating chamber. The decorative layer of hard material is deposited by a reactive HIPIMS-process, and the energy content in the power pulses is controlled in such a manner that the deposited layer of hard material has a homogeneous colour, a high degree of smoothness and a high strength.

Claims

1. A method for coating at least parts of a surface of a substrate or for manufacturing substrates with a part of the surface provided with a decorative hard material layer in a coating chamber, whereby a reactive HIPIMS-process is applied for manufacturing a hard-material layer, which makes use of reactive gases, an inert gas and of at least one target comprising titanium which reacts during operating the reactive HIPIMS-process with the reactive gases in such a manner, that, thereby, a predetermined layer color is produced, wherein the reactive HIPIMS-process is operated by applying: power pulse-sequences with an energy content of at least 0.2 Joule/cm.sup.2 with respect to a surface of the at least one target wherein each power pulse-sequence comprises a burst of pulses with a first time between each pulse, and each power-pulse sequence is separated from each other by a second time, wherein the second time is greater than the first time, and adjusting power density per power pulse-sequence by adjusting a power of the burst of pulses of the power pulse-sequence, wherein the power of each pulse of the power pulse-sequence is held constant at a maximum value for a first predetermined period of time and is reduced to a reference value and held constant at the reference value for a second predetermined period of time before increasing to form another pulse, wherein the adjusting power density per power pulse-sequence includes adjusting a duration of at least two of the pulses of the power pulse-sequence, while maximum values of the at least two of the pulses are held substantially equal; and wherein for conducting the reactive HIPIMS-process applied for manufacturing the hard-material layer, the inert gas includes Ar, the reactive gases include N.sub.2 and C.sub.2H.sub.2 and are used for producing TiCN-layers, wherein a flow rate of Ar is 150 to 210 sccm, a flow rate of N.sub.2 is 20 to 50 seem and a flow rate of C.sub.2H.sub.2 is greater than 0 to less than or equal to 30 sccm, wherein the power pulse-sequences cause the coating to achieve a homogeneous color appearance.

2. The method of claim 1 wherein the energy content in the power pulse-sequences, with respect to the surface of the at least one target, is at least 1 Joule/cm.sup.2 per power pulse-sequence.

3. The method of claim 1 wherein the power density is at least 100 W/cm.sup.2.

4. The method of claim 3 wherein the power density is at least 500 W/cm.sup.2.

5. The method of claim 4 wherein the power density is at least 1000 W/cm.sup.2.

6. The method according to claim 1, wherein a temperature of the substrate is below 200° C. for coating temperature-sensitive substrates.

7. The method of claim 1, wherein a concentration of nitrogen in the coating chamber is controlled by regulating the flow rate of N2, so of a nitrogen gas flow and the nitrogen gas flow is regulated so, that the homogenous color appearance accords with a color according to Gold 2N18 or 1N14 or 3N18.

8. Hard-material layer, manufactured by making use of a method according claim 1, characterized by the fact, that the hard-material layer has a hardness of at least 30 GPa.

9. The method of claim 1, wherein a height of the coating chamber is 400 mm or more.

10. The method of claim 1, wherein the adjusting power density per power pulse-sequence causes an immediately subsequent cycle of a power pulse-sequence to have a different power density from an immediately preceding cycle of a power-pulse sequence, respectively.

11. The method of claim 1, wherein the reference value is zero.

12. A method for coating at least parts of a surface of a substrate or for manufacturing substrates with a part of the surface provided with a decorative hard-material layer in a coating chamber, whereby a reactive HIPIMS-process is applied for manufacturing a hard-material layer, which makes use of reactive gases, an inert gas and of at least one target comprising titanium which reacts during operating the reactive HIPIMS-process with the reactive gases in such a manner, that, thereby, a predetermined layer color is produced, wherein the reactive HIPIMS-process is operated by applying: power pulse-sequences with an energy content of at least 0.2 Joule/cm.sup.2 with respect to a surface of the at least one target wherein each power pulse-sequence comprises a burst of pulses with a first time between each pulse, and each power-pulse sequence is separated from each other by a second time, wherein the second time is greater than the first time, and adjusting power density per power pulse-sequence by adjusting a power of the burst of pulses of the power pulse-sequence, wherein the power of a first pulse of the power pulse-sequence is held constant at a first maximum value for a first predetermined period of time and is reduced to a reference value and held constant at the reference value for a second predetermined period of time before increasing to a second maximum value of a second pulse, wherein the adjusting power density per power pulse-sequence includes adjusting the second maximum value to be greater than the first maximum value, while a duration of the second maximum value is substantially equal to a duration of the first maximum value; and wherein for conducting the reactive HIPIMS-process applied for manufacturing the hard-material layer, the inert gas includes Ar, the reactive gases include N.sub.2 and C.sub.2H.sub.2 and are used for producing TiCN-layers, wherein a flow rate of Ar is 150 to 210 sccm, a flow rate of N.sub.2 is 20 to 50 seem and a flow rate of C.sub.2H.sub.2 is greater than 0 to less than or equal to 30 sccm, wherein the power pulse-sequences cause the coating to achieve a homogeneous color appearance.

13. The method of claim 12 wherein the energy content in the power pulse-sequences, with respect to the surface of the at least one target, is at least 1 Joule/cm.sup.2 per power pulse-sequence.

14. The method of claim 12 wherein the power density is at least 100 W/cm.sup.2.

15. The method of claim 14 wherein the power density is at least 500 W/cm.sup.2.

16. The method of claim 15 wherein the power density is at least 1000 W/cm.sup.2.

17. The method according to claim 12, wherein a temperature of the substrate is below 200° C. for coating temperature-sensitive substrates.

18. The method of claim 12, wherein a concentration of nitrogen in the coating chamber is controlled by regulating the flow rate of N2, so, that the homogenous color appearance accords with a color according to Gold 2N18 or 1N14 or 3N18.

19. Hard-material layer, manufactured by making use of a method according claim 12, characterized by the fact, that the hard-material layer has a hardness of at least 30 GPa.

20. The method of claim 12, wherein a height of the coating chamber is 400 mm or more.

21. The method of claim 12, wherein the adjusting power density per power pulse-sequence causes an immediately subsequent cycle of a power pulse-sequence to have a different power density from an immediately preceding cycle of a power-pulse sequence, respectively.

22. The method of claim 12, wherein the reference value is zero.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) In the following the present invention is further described by means of some examples and with the help of the FIGS. 1 to 4.

(2) FIG. 1 shows CIELab color coordinates for TiN- and TiCN layers manufactured according to one aspect of the invention;

(3) FIG. 2 shows CIELab color coordinates and brightness factor measured for TiCN-layers according to another aspect of the invention;

(4) FIG. 3 shows CIELab color coordinates and brightness factor for gold colored TiN-layers according to another aspect of the invention; and

(5) FIG. 4 shows exemplary representations of possible power courses at a target.

DESCRIPTION

(6) FIG. 1 shows the CIELab color coordinates a* and b*, which were measured at TiN- and TiCN-layers manufactured according to the invention and which were deposited at an increasing nitrogen gas flow or respectively at an increasing acetylene gas flow by means of the setting different nitrogen gas flows, TiN-layers with different gold standards could be manufactured. In a similar manner TiCN-layers with different colors could be manufactured by setting different acetylene gas flows.

(7) FIG. 2 shows the CIELab color coordinates a* and b* and the brightness factors L* which were measured at TiCN-layers manufactured according to the invention and which layers were applied in the same coating batch from Ti-Targets and under the use of a N.sub.2- and C.sub.2H.sub.2-containing reactive gas flow on different substrates. The substrates were distributed before initiation of the coating method according to the invention along the height of the coating chamber so as to check upon homogeneity of the color appearance along the height extent of the coating chamber. A very good homogeneity of the layer color within the coating chamber could be confirmed. The coating height, that is the height of the coating chamber exploited for the coating of the substrates was, in this example, 400 mm whereby, for operating a method according to the present invention, the coating height is not limited on this height, the coating height may be smaller or larger.

(8) FIG. 3 shows the CIELab color coordinates a* and b* and the brightness factor L* which were measured from gold colored TiN-layers deposited according to the invention and which were applied in the same coating batch and from TiN-targets and by using a N.sub.2-containing reactive gas flow upon different substrates. The substrates were distributed before initiating the coating method according to the invention along the height of the coating chamber so as to check upon homogeneity of the golden color appearance along the height of the coating chamber. A very good homogeneity of the layer color within the coating chamber could be confirmed. The coating height i.e. the height within the coating chamber defined for coating substrates was in this example again 400 mm. Nevertheless, for operating of a method according to the invention, the coating height is not limited to this height, which means, the coating height may be smaller or larger.

(9) An outstanding homogeneity of the color appearance along the entire coating height could be confirmed for the TiCN- and TiN-layers deposited according to the invention, as may be seen in the FIGS. 2 and 3.

(10) Gold-colored layers with a multilayer layer-structure of a multitude of alternatingly deposited thin TiN- and ZrN-layers may also be perfectly manufactured by making use of a method according to the present invention. This, as an example in that one, using at the same HIPIMS-coating process uses, nitrogen as reactive gas and at least one HIPIMS-target of Ti as well as a HIPIMS-target of Zr positioned in the coating chamber so and operated so that TiN- and ZrN-layers are alternatingly deposited on the substrates to be coated.

(11) According to the present invention different colors of the gold standard may be easily produced at hard-material layers deposited according to the present invention by setting different nitrogen flows, this especially when using Ti-containing targets or preferably targets which consist of titanium.

(12) According to the invention the nitrogen flow may be exactly regulated so that the color appearance accords preferably a color according to that of gold 2N18 or 1N14 or 3N18.

(13) The inventor has recognized that especially hard-material layers with nice colors for decorative applications may be manufactured by using targets which comprise titanium or titanium and aluminum or zirconium.

(14) According to a preferred form of realization of a method according to the invention at least one target is used which consists of titanium or of titanium and aluminum or of zirconium.

(15) For manufacturing nitrides, oxides, carbides, oxynitrides or carbonitrides which may provide different layer characteristics and color appearances to the layers manufactured according to the present invention, nitrogen gas or oxygen gas or a carbon-containing gas, e.g. C.sub.2H.sub.2 or CH.sub.4 or a mixture of such gases, e.g. N.sub.2 and C.sub.2H.sub.2, may be fed to the coating chamber for operating the HIPIMS-process. Preferably a coating according to the present invention is applied to substrates at which the hard-material layer shall have a decorative function.

(16) Methods according to the invention and as described here are especially and very highly suited for coating different decorative objects as substrates which may be of different materials. A highly significant advantage of using a method according to the present invention for manufacturing decorative hard-material layers is that one may also coat temperature sensitive substrates which, as an example, may not be exposed to temperatures above 200° C. This becomes possible because the HIPIMS-processes according to the invention may be operated so that the duration of a power pulse, t.sub.Puls, or the duration of the single pulses within a power pulse-sequence or the duration of a power pulse-sequence, t.sub.Pussequenz, as well as the respective pulse pauses (Duty-Cycle) and the relevant target surface may be selected so that very low coating temperatures, i.e. very low substrate temperatures may be met during the coating process without occurrence of process instabilities.

(17) According to the invention one may produce hard-material layers with different colors of the gold standard by setting of a respective nitrogen flow but also other hard-material layers may be produced, the color appearance thereof being adjustable within a large coating range by setting of the respectively applied reactive gas flow or of the concentration of different reactive gases.

(18) In the frame of the present invention and as an example, decorative hard-material layers with predetermined color and with an excellent homogeneous appearance, with very high hard hardness and super-smooth surface were manufactured according to the invention. The reactive gas flows used as well as the measured mechanical characteristic of the manufactured hard-material layers are shown in table 1. All the processes were realized at substrate temperatures between 150° C. and 500° C.

(19) TABLE-US-00001 TABLE 1 Reactive gas flows as used and mechanical characteristics of TiN-, TiCN-, and TiC- hard-material layers deposited according to the present invention for achieving different predetermined homogeneous colors for decorative applications Ar N.sub.2 C.sub.2H.sub.2 Hardness .sub.HIT E-Modul Example [sccm] [sccm] [sccm] [GPa] [GPa] 1 210 50 0 33 420 2 210 50 6 32 440 3 210 50 14 37 400 4 210 30 20 36.3 450 5 210 40 20 44 462 6 210 20 24 38.3 426 7 150 30 30 42.4 465

(20) The very high mechanical stability of those hard-material layers and respectively the very good combination of hardness and E-Module allow that these layers provide at the objects coated therewith a durable color appearance.

(21) These layers have a very good adherence to the substrate and have a very high wear resistance. Consequently, these decorative hard-material layers may be used over years.

(22) The methods according to the present invention allow to reach highly homogeneous color appearances even if the substrates have very extended surfaces to be coated.

(23) Methods according to the present invention are especially suited whenever a multitude of substrates are to be distributed along the height extend of a large coating chamber and a homogeneous color appearance over all substrates shall be reached.