Hard Material Layer

Abstract

A hard material layer is deposited on a workpiece as a functional layer by an arc-PVD method. The layer is essentially an electrically insulating oxide of at least one of the metals (Me) of the transition metals of the sub-groups IV, V, VI of the periodic table and Al, Si, Fe, Co, Ni, Co, or Y and the functional layer (32) contains no noble gas or halogen.

1 . Hard material layers deposited on a workpiece ( 30 ) as Arc-PVD functional layer ( 32 ) wherein this layer is formed substantially as an electrically insulating oxide of at least one of the metals (Me) from the transition metals of subgroups IV, V, VI of the periodic system of elements and Al, Si, Fe, Co, Ni, Y, characterized in that the functional layer ( 32 ) has a content of inert gas and/or of a halogen of less than 2%. 
     
     
         2 . Hard material layer as claimed in  claim 1 , characterized in that the content of inert gas in the functional layer ( 32 ) is maximally 0.1%, preferably maximally 0.05%, and/or that of halogen maximally 0.5%, preferably maximally 0.1%, preferably comprises substantially no inert gas and/or halogen. 
     
     
         3 . Hard material layer as claimed in  claim 1 , characterized in that the functional layer ( 32 ) has a thickness in the range from 0.5 μm to 12 μm, preferably 1.0 to 5 μm. 
     
     
         4 . Hard material layer as claimed in  claim 1 , characterized in that the functional layer ( 32 ) is substantially an aluminum metal mixed oxide of the form (Al x M 1-x ) y O z  wherein Me is preferably one of the metals Al, Cr, Mo, Zr, Fe, Co, Ni, Y, singly or also in mixtures thereof. 
     
     
         5 . Hard material layer as claimed in  claim 4 , characterized in that Me is the metal chromium and forms the form (Al x Cr 1-x ) y O z . 
     
     
         6 . Hard material layer as claimed in  claim 5 , characterized in that the fraction of the metal chromium in the layer is 5 to 80 atom %, preferably 10 to 60 atom %. 
     
     
         7 . Hard material layer as claimed in  claim 1 , characterized in that the functional layer ( 32 ) is substantially a stoichiometric aluminum oxide layer of the form Al 2 O 3 . 
     
     
         8 . Hard material layer as claimed in  claim 1 , characterized in that the functional layer ( 32 ) forms the outermost layer or an additional support layer, with at least one superjacent cover layer ( 35 ), such as in particular a friction-reducing layer ( 35 ). 
     
     
         9 . Hard material layer as claimed in  claim 1 , characterized in that the functional layer ( 32 ) has a temperature resistance of greater than 800° C. and that it is chemically stable. 
     
     
         10 . Workpiece with a hard material layer as claimed in  claim 1 , characterized in that the workpiece ( 30 ) is a tool, a machine part, preferably an indexable insert. 
     
     
         11 . Workpiece as claimed in  claim 10 , characterized in that between the functional layer ( 32 ) and the workpiece ( 30 ) a further layer forming an intermediate layer ( 31 ) is disposed, and this layer forms in particular an adhesion layer ( 31 ) and such adhesion layer preferably comprises one of the metals of the subgroups IV, V and VI of the periodic system of elements and/or Al, Si, Fe, Co, Ni, Y or a mixture thereof. 
     
     
         12 . Workpiece as claimed in  claim 11 , characterized in that the metals of the intermediate layer ( 31 ) are compounds with N, C, O, B or mixtures thereof, the compound with N being preferred. 
     
     
         13 . Workpiece as claimed in  claim 11 , characterized in that the layer thickness of the intermediate layer ( 31 ) is 0.05 to 5 μm, preferably is in the range of 0.1 to 0.5 μm. 
     
     
         14 . Workpiece as claimed in  claim 10 , characterized in that at least one of the layers, in particular the functional layer ( 32 ) and or the intermediate layer ( 31 ) is implemented as a progression layer ( 34 ), such as from metallic over nitridic and/or from nitridic to nitrooxidic and up to the oxide. 
     
     
         15 . Workpiece as claimed in  claim 10 , characterized in that at least one of the layers, in particular the functional layer ( 32 ), is implemented as a multilayer system ( 33 ) with different material composition, in which preferably several deposits ( 33 ) alternately repeat with respect to their essential composition and that the multilayer system ( 33 ) preferably comprises at least 3 deposits. 
     
     
         16 . Workpiece as claimed in  claim 15 , characterized in that the repeating layer sequence pairs of the layer system alternately change the material composition, such as preferably from an Me 1  to an Me 2 -oxide and/or from an Me 1 -nitride to an Me 1 -oxide and/or from an Me 1 -nitride to an Me 2 -oxide. 
     
     
         17 . Workpiece as claimed in  claim 15 , characterized in that the repeating layer sequence pair of the layer system alternately comprises the material composition of (Al x Cr 1-x ) y N z  and (Al x Cr 1-x ) y O z  and these preferably in stoichiometric composition such as (Al x Cr 1-x )N and (Al x Cr 1-x ) z O 3 . 
     
     
         18 . Workpiece as claimed in  claim 15 , characterized in that the repeating layer sequence pairs of the layer system comprise alternately the material composition (AlZr) x N y  and (AlZr) x O y  and these preferably in stoichiometric composition such as (Al x Zr 1-x )N and (Al x Zr 1-x ) 2 O 3 . 
     
     
         19 . Workpiece as claimed in  claim 15 , characterized in that the multilayer system ( 33 ) comprises at least 20 deposits, preferably up to 500 deposits. 
     
     
         20 . Workpiece as claimed in  claim 15 , characterized in that the layer thickness of one deposit of the multilayer system ( 33 ) is in the range of 0.01 to 0.5 μm, preferably in the range of 0.02 to 0.1 μm. 
     
     
         21 . Method for coating a workpiece ( 3 ) in a vacuum process installation ( 1 ) with a hard material layer ( 32 ) deposited as functional layer, which is implemented as an electrically insulating oxide of at least one of the metals (Me) of the transition metals of the subgroups IV, V, VI of the periodic system of elements and Al, Si, Fe, Co, Ni, Co, Y, and that the layer is deposited with an arc evaporator source ( 5 ) operated with a DC power supply ( 13 ), characterized in that a pulsed power supply ( 16 ,  16 ′) is superimposed, wherein the target ( 5 ′,  20 ) of the arc evaporator source ( 5 ,  20 ) comprises one of the metals and the metal vapor-deposited in this way is reacted to the oxide in an oxygen-containing reactive gas atmosphere. 
     
     
         22 . Method as claimed in  claim 21 , characterized in that in the reactive gas atmosphere of the process chamber of the vacuum installation ( 1 ) so small a quantity of inert gas and/or halogen gas is supplied that in the deposited layer maximally 0.5% of such gases, preferably substantially none of these gases, are incorporated. 
     
     
         23 . Method as claimed in  claim 21 , characterized in that two DC-fed arc evaporator sources ( 5 ,  20 ) are operated, wherein additionally a single pulsed power supply ( 16 ) is connected to the two sources ( 5 ,  20 ) and in this manner forms a dual pulse arc evaporator configuration ( 5 ,  20 ). 
     
     
         24 . Method as claimed in  claim 21 , characterized in that the workpiece is substantially comprised of steel, an iron-, chromium-, cobalt- or nickel-containing alloy of one or several metals, a hard metal, a ceramic, a cermet, or cubic boron mononitride, wherein at least one further layer is deposited by means of a PVD method and one of the layers is an adhesion layer ( 31 ) which borders directly on the workpiece ( 30 ), wherein the or at least one of the following layers, the functional layer ( 32 ), is substantially comprised of Al 2 O 3  or (AlMe) 2 O 3 , wherein Me comprises at least one transition metal of the group IV, V or VI of the periodic system of elements or silicon and at least the aluminum or aluminum metal oxide layer is deposited with an arc evaporator ( 5 ,  20 ), in which from at least one target ( 5 ′,  20 ′), poisoned on the surface, aluminum oxide, metal oxide or aluminum metal oxide is vaporized in an oxygen-containing atmosphere. 
     
     
         25 . Method as claimed in  claim 21 , characterized in that the coating attains a roughness value R a  of not less than 0.2 μm. 
     
     
         26 . Method as claimed in  claim 21 , characterized in that at least one further layer is deposited which comprises substantially an aluminum-free one or several metal oxides comprising oxide layer, wherein the metal oxide comprises at least one transition metal of group IV, V or VI of the periodic system of elements or silicon, however preferably chromium or zirconium. 
     
     
         27 . Method as claimed in  claim 24 , characterized in that the adhesion layer ( 31 ) comprises at least one of the transition metals of group IV, V or VI of the periodic system of elements and/or aluminum or silicon. 
     
     
         28 . Method as claimed in  claim 24 , characterized in that the adhesion layer ( 31 ) comprises a hard layer which comprises a nitride, carbide or boride, at least one of the transition metals of group IV, V or VI of the periodic system of elements and/or aluminum or silicon or a mixture of these compounds. 
     
     
         29 . Method as claimed in  claim 21 , characterized in that the functional layer ( 32 ) is deposited as hard material layer system which comprises several deposits ( 33 ) of a nitride, carbide, boride or oxide of at least one of the transition metals of group IV, V or VI of the periodic system of elements and/or aluminum or silicon or a mixture of these compounds, wherein at least directly succeeding deposits differ by the stoichiometry of their metal or nonmetal content. 
     
     
         30 . Method as claimed in  claim 29 , characterized in that the deposition of the hard material layer system ( 32 ) takes place with one or several deposits ( 33 ) of aluminum chromoxide-containing layers. 
     
     
         31 . Method as claimed in  claim 29 , characterized in that transitions between the individual deposits ( 33 ) of the hard material layer system ( 32 ) with respect to the stoichiometry of their metal or nonmetal content are increased or decreased smoothly and continuously or stepwise. 
     
     
         32 . Method as claimed in  claim 29 , characterized in that the layer of the individual deposits of the hard material layer system ( 32 ) is deposited with a thickness between 0.01 and 0.5 μm, preferably betwen 0.02 and 0.1 μm. 
     
     
         33 . Method as claimed in  claim 30 , characterized in that nitride-, carbide- or boride-containing layers are deposited alternately with aluminum chromoxide-containing layers. 
     
     
         34 . Method as claimed in  claim 24 , characterized in that at least one transition from the adhesion layer ( 31 ) to the aluminum oxide-containing layer or to the hard material layer system ( 32 ) or from the hard material layer system ( 32 ) or the aluminum oxide-containing layer to the cover layer ( 35 ) with respect to the stoichiometry of their metal or nonmetal content are increased or decreased smoothly and continuously or stepwise. 
     
     
         35 . Method as claimed in  claim 21 , characterized in that the aluminum oxide-containing layer is substantially deposited as (Al 1-x Cr x ) 2 O 3 , wherein 0.05<×<0.80, however preferably 0.01<×<0.60. 
     
     
         36 . Method as claimed in  claim 21 , characterized in that as workpiece ( 30 ) a tool, in particular a cutting, forming or injection molding tool is coated. 
     
     
         37 . Method as claimed in  claim 21 , characterized in that as workpiece ( 30 ) a part, in particular a part for an internal combustion engine or a turbine, is coated.