TiB2 layers and manufacture thereof

Abstract

A workpiece having a coating which has at least one TiB.sub.2 layer, characterized in that the TiB.sub.2 layers have a texture, in the XRD-spectrum, which leads to significant peaks which display a pronounced (002) orientation. The invention also relates to a method for producing said type of workpiece with a coating.

Claims

1. A method for coating at least one work piece having a layer containing TiB.sub.2 with the following steps: placing a work piece that is to be coated into a coating chamber; depositing the layer containing TiB.sub.2 onto the work piece using a nonreactive high power magnetron sputtering process using no pulse generator in an atmosphere containing a working gas by acting on TiB.sub.2 targets, wherein at least two TiB.sub.2 targets are acted on with a constantly high power of output of greater than 20 kW from a DC power source, such that a power density results in a current density at each of the at least two TiB.sub.2 targets of locally greater than 0.2 A/cm.sup.2, with the at least two TiB.sub.2 targets processing a power of no greater than 10 kW, averaged over time, wherein the nonreactive high power magnetron sputtering process has at first only a first TiB.sub.2 target of the at least two TiB.sub.2 targets acted on with full power through outputs of the DC power source and thus with a high power density, then a second TiB.sub.2 target of the at least two TiB.sub.2 targets is connected to outputs of the DC power source, wherein an impedance of the second TiB.sub.2 target is higher than an impedance of the first TiB.sub.2 target, then the first TiB.sub.2 target is disconnected from the outputs of the DC power source, so that power output occurs essentially via the second TiB.sub.2 target, wherein a roughness of the layer containing TiB.sub.2 is influenced by increasing a partial pressure of the working gas to at least 0.2 Pa during the nonreactive high power magnetron sputtering process to decrease the roughness of the layer containing TiB.sub.2, and wherein the layer containing TiB.sub.2 has a texture that produces significant peaks in the XRD spectrum, which display a pronounced (001)-orientation.

2. The method according to claim 1, wherein the working gas contains at least argon.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows the influence of the partial pressure of the working gas on the roughness of the TiB.sub.2 layers in the example.

(2) FIG. 2 shows that the hardness of the layers and the elasticity modulus of the layers remained constantly good in the example.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(3) According to the invention, the layers are produced by means of a sputtering process in which a constantly high power output from the power source occurs. A plurality of sputtering cathodes are used for this. Unlike in the conventional HiPIMS process, no pulse generator is used and instead, at first only a first sputtering cathode is acted on with the full power of the power source and thus with a high power density. Then a second sputtering cathode is connected to the outputs of the power source. In this case, not much happens at first because at this point, the impedance of the second sputtering cathode is far higher than the impedance of the first sputtering cathode. Only when the first sputtering cathode is disconnected from the outputs of the power source does the power output occur essentially via the second sputtering cathode. The corresponding high power magnetron sputtering process is described in greater detail in WO 2013060415. Typically, the power source therein is operated at on the order of 60 kW. Typical powers to which the sputtering cathodes are subjected, averaged over time, are on the order of 8 kW.

(4) The inventors have discovered that when such a method is used with ceramic targets such as TiB targets used as sputtering cathodes, it is possible to reproducibly produce layers with very good mechanical properties. The inventors have also discovered that in such a nonreactive process, by adjusting the partial pressure of the working gas, it is possible to influence the layer roughness directly, in fact without this having a significantly negative influence on the above-mentioned mechanical properties.

(5) In the example, TiB.sub.2 layers were produced. These layers have a texture and produce significant peaks in the XRD spectrum, which display a pronounced (001)-orientation. Such an orientation turns out to be very advantageous in many applications in which hard material coatings are required.

(6) In order to demonstrate the influence of the partial pressure of the working gas on the roughness, different argon gas flows were used. With an argon gas flow of 80 sccm, roughness values of Ra=0.14 m and Rz of 0.115 m were measured; with an argon gas flow of 160 sccm, roughness values of Ra=0.115 m and Rz of 0.095 m were measured; and with an argon gas flow of 300 sccm, roughness values of Ra=0.06 m and Rz of 0.05 m were measured. In the coating system that was used, an argon flow of 80 sccm corresponded to a partial pressure of 0.2 Pa, an argon flow of 160 sccm corresponded to a partial pressure of 0.4 Pa, and an argon flow of 300 sccm corresponded to a partial pressure of 0.75 Pa. This is shown in FIG. 1.

(7) The hardness of the layers and the elasticity modulus of the layers, however, remained constantly good. This is shown in FIG. 2.

(8) The present invention, therefore, has disclosed a method for efficiently and economically producing TiB.sub.2 layers. This method yields TiB.sub.2 layers with previously unknown hardness combined with very low roughness values. This is of significant interest primarily in connection with applications on sliding, surfaces. The previously conventional PVD vaporization processes did not permit the production of such hard TiB.sub.2 layers.