Method for manufacturing a metal-borocarbide layer on a substrate

Abstract

The invention relates to a PVD process for coating a substrate with a layer containing at least one microcrystalline metallic borocarbide phase. During the PVD process, the source output is pulsed such that the at least one peak of which the half intensity width allows conclusions to be drawn about the presence of a microcrystalline phase of the metallic borocarbide layer can be identified in the x-ray spectrum of a layer produced in this way at a substrate temperature below 600 C.

Claims

1. A PVD method for coating a substrate with a coating which at least contains a microcrystalline metal-borocarbide phase, characterized by the facts, that in the frame of the PVD method, the source power is pulsed so that in the x-ray spectrum of thereby deposited layer at a substrate temperature below 600 C. at least one peak may be identified, the half value width thereof allowing the conclusion that a microcrystalline phase of the metal-borocarbide is present, wherein the PVD method comprises a HIPIMS method.

2. The method of claim 1, characterized by the fact that the sputtering method is operated at least to a part with a current density larger than 100 W/cm.sup.2 as the HIPIMS method.

3. The method according to claim 1, characterized by the fact that the PVD method is operated with a target, in which a metal is present as a ceramic compound.

4. The method according to claim 3, characterized by the fact that the ceramic compound is a metal-borocarbide.

5. The method according to claim 1, characterized by the fact that at least during a part of the PVD method, a negative bias is applied to the substrate to be coated.

6. The method according to claim 1, characterized by the fact that the metal-borocarbide is a material according to the formula Me.sub.2BC whereby Me is an element out of the group formed by Cr, Zr and Mo.

7. The method according to claim 1, characterized by the fact that the method is operated so that the at least one peak has an amplitude which is at least twice the largest amplitude of a measuring value, which indicates presence of a nano-crystalline and/or amorphous-phase in a 2Theta x-ray spectrum from 20 to 70.

8. A workpiece with a metal-borocarbide coating and coated by a method according to claim 1, characterized by the fact that in the x-ray spectrum of the coating at least one peak may be identified the half-value width thereof being indicative for the presence of a micro-crystalline phase of the metal-borocarbide.

9. A workpiece according to claim 8, characterized by the fact the metal-borocarbide is a material according to the formula Me.sub.2BC, whereby Me is an element out of the group formed by Cr, Zr and Mo.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows x-ray diffraction spectra of surfaces coated at different substrate temperatures;

(2) FIG. 2 shows x-ray diffraction spectra of surfaces coated using pulsed power;

(3) FIG. 3 shows x-ray diffraction spectra of surfaces coated using different methods; and

(4) FIG. 4 shows x-ray diffraction spectra of surfaces coated using different methods.

DETAILED DESCRIPTION OF THE INVENTION

(5) At first and for comparison purposes Mo.sub.2BC was deposited in a small coating chamber and by means of DC sputtering. The respective coating parameters are:

(6) TABLE-US-00001 Generator DC Power 50 W Target 50 mm compound target Substrate temperature 300-700 C. Basic pressure 10.sub.5 mbar

(7) Considered are the substrate temperature effect, roughness and hardness as well as the module of elasticity.

(8) The coatings were applied at different temperatures. FIG. 1 respectively shows x-ray diffraction spectra (2 theta) of surfaces coated at substrate temperatures of 300 C., 450 C., 550 C., 650 C. and 700 C. It becomes apparent that only above 600 C. one may consider crystalline phases being present. Below 550 C. Ts amorphous or nano-crystalline phases are present. The modulus of elasticity as well as hardness increase as the substrate temperature decreases.

(9) In opposition thereto and when applying the deposition by means of a pulsed power, already at 580 C. significant peaks were measured as shows the comparison in FIG. 2. Thereby, the applied method was pulsed magnetron sputtering. The increased plasma density when pulsing the increased ion bombardment and the increased mobility of the adatomes leads to an increased degree of phase formation.

(10) Predominant is the crystalline phase already at a substrate temperature of 580 C. if HIPIMS is applied as clearly shown by FIG. 3. In the present context HPPMS and HIPIMS address the same technique. This leads to the highest degree of crystallization and to a texturized structure. In FIG. 4 the x-ray spectra of different approaches at similar substrate temperatures (560 C. to 580 C.) are shown. The HIPIMS coatings were realized with the help of two different commercially available sources. The same temperature behavior comes up when coating steel substrates. Thus, the selection of the substrate has no influence in this case.

(11) Below 600 C. substrate temperature applying a substrate bias of 100V has no significant effect upon the phase formation at un-pulsed DC-sputtering. In opposition therefore, crystalline phases of Mo.sub.2BC come up at least already at 480 C. substrate temperature, if a HIPIMS technique is applied and simultaneously a negative bias of e.g. 100V is applied to the substrate.

(12) A PVD-method of coating of a substrate with a layer at least containing a microcrystalline metalborocarbide phase was disclosed, whereby the method is characterized by pulsating the source power in the frame of the PVD process so that in the x-ray spectrum of a layer so deposited at a substrate temperature below 600 C., at least one peak may be identified with a half-value width which allows to conclude that a microcrystalline phase of the metalborocarbide is present.

(13) The method may be a pulsed arc PVD-method but is preferably a pulsed sputtering method.

(14) The sputtering method according to the invention may at least to a part be operated with a current density larger than 100 W/cm.sup.2 as a HIPIMS method.

(15) The PVD method according to the invention may be operated with a target, in which a metal is present in form of a ceramic compound, as an example as a metalborocarbide.

(16) The method according to the invention, the metal-borocarbide may be a material according to the formula Me.sub.2BC whereby Me is an element out of the group formed by Cr, Zr and Mo.

(17) The method may be realized so that the at least one peak has an amplitude with at least double extent with respect to the largest amplitude of a measuring value which suggests a nano-crystalline and/or amorphous phase in a 2Theta x-ray spectrum from 20 to 70. This may e.g. be achieved by a respectively selected substrate bias at a HIPIMS method as show the figures.

(18) By means of the new method, a with a metal-borocarbide coating may be manufactured at which within the x-ray spectrum of the coating at least one peak may be identified, the half value width thereof being indicative for the presence of a microcrystalline phase of the metalborocarbide.

(19) The metalborocarbide may be a material according to the formula Me.sub.2BC whereby Me is an element out of the group formed by Cr, Zr and Mo.