Wear-resistant coating and process for producing it

Abstract

The present invention relates to a process for producing a wear-resistant coating and to a wear-resistant coating on predetermined surfaces ( 2 ) of machine or engine parts ( 1 ) consisting of a sintered material which are exposed to frictional wear, for fuel feed units in particular, comprising at least one metal-free amorphous hydrocarbon layer ( 5 ) with sp 2 - and sp 3 -hybridized carbon applied to the predetermined surface ( 2 ) of the machine or engine part ( 1 ) for reducing friction and increasing the wear resistance of the predetermined surface ( 2 ) of the machine or engine part ( 1 ).

1 . A wear-resistant coating on predetermined surfaces ( 2 ) of machine or engine parts ( 1 ) comprising sintered materials which are exposed to frictional wear, in fuel feed units, comprising at least one metal-free amorphous hydrocarbon layer ( 5 ) with sp 2 - and sp 3 -hybridized carbon applied to the predetermined surface ( 2 ) of a machine or engine part ( 1 ) for reducing friction and increasing the wear resistance of the predetermined surface ( 2 ) of the machine or engine part ( 1 ).  
   
   
       2 . A wear-resistant coating of  claim 1 , wherein the amorphous hydrocarbon layer ( 5 ) has a hydrogen fraction of at most 20 atomic %.  
   
   
       3 . A wear-resistant coating of  claim 1 , wherein the amorphous hydrocarbon layer has process-related impurities of less than 1 atomic %.  
   
   
       4 . A wear-resistant coating of  claim 1  wherein the amorphous hydrocarbon layer ( 5 ) has a thickness of approximately 1.0 μm to 4.0 μm.  
   
   
       5 . A wear-resistant coating of  claim 1  wherein at least one adhesion promoting layer ( 3 ) and/or at least one intermediate layer ( 4 ) is provided between the predetermined surface ( 2 ) of the machine or engine part ( 1 ) and the amorphous hydrocarbon layer ( 5 ).  
   
   
       6 . A wear-resistant coating of  claim 5 , wherein at least one intermediate layer ( 4 ) is formed as a metal-containing hydrocarbon layer.  
   
   
       7 . A wear-resistant coating of  claim 6 , wherein the metal components of the metal-containing hydrocarbon layer ( 4 ) are selected from the group consisting of W, Ti, Hf, Ge and a combination of the aforementioned elements.  
   
   
       8 . A wear-resistant coating of  claim 5  wherein at least one intermediate layer ( 4 ) has a thickness of approximately 0.5 μm to 2.0 μm.  
   
   
       9 . A wear-resistant coating of  claim 5  wherein at least one adhesion promoting layer ( 3 ) comprises at least one metallic substances selected from the group consisting of borides, carbides and nitrides of the transition metals.  
   
   
       10 . A wear-resistant coating of  claim 5  wherein the adhesion promoting layer ( 3 ) has a thickness of approximately 0.1 μm to 0.5 μm.  
   
   
       11 . A wear-resistant coating of  claim 1  wherein the predetermined surface ( 2 ) of the machine or engine part ( 1 ) consists of a hardened sintered steel.  
   
   
       12 . A cam plate ( 1 ) produced with a contact surface produced from a sintered material of  claim 1  as a middle plate of a pump device of a fuel feed unit.  
   
   
       13 . A cam plate of  claim 12  wherein the middle plate is part of a valve gear component selected from the group consisting of bucket tappets, camshafts, hydraulic supporting and insertion elements, rolling bearing components, control pistons release bearings, piston pins, bearing bushes and linear guides.  
   
   
       14 . A process for producing a wear-resistant coating on predetermined surfaces ( 2 ) of machine or engine parts ( 1 ) comprising sintered materials which are exposed to frictional wear, in fuel feed units, comprising applying at least one metal-free amorphous hydrocarbon layer ( 5 ) with sp 2 - and sp 3 -hybridized carbon to the predetermined surface ( 2 ) of a machine or engine part ( 1 ) for reducing friction and increasing the wear resistance of the predetermined surface ( 2 ) of the machine or engine part ( 1 ).  
   
   
       15 . The process of  claim 14 , wherein the amorphous hydrocarbon layer ( 5 ) is deposited onto the predetermined surface ( 2 ) of the machine or engine part ( 1 ) by means of a PVD and/or a (PA) CVD process.  
   
   
       16 . The process of  claim 14 , wherein the amorphous hydrocarbon layer ( 5 ) is formed with a hydrogen fraction of at most 20 atomic %.  
   
   
       17 . The process of  claim 14  wherein the amorphous hydrocarbon layer ( 5 ) is formed with process-related impurities of less than 1 atomic %.  
   
   
       18 . The process of  claim 14  wherein the amorphous hydrocarbon layer ( 5 ) is formed with a thickness of approximately 1.0 μm to 4.0 μm.  
   
   
       19 . The process of  claim 14  wherein, before depositing of the amorphous hydrocarbon layer ( 5 ), the predetermined surface ( 2 ) of the machine or engine part ( 1 ) undergoes cleaning, in various cleaning baths, with a subsequent outgassing operation in a cleaning.  
   
   
       20 . The process of  claim 14  wherein at least one adhesion promoting layer ( 3 ) and/or at least one intermediate layer ( 4 ) is formed between the predetermined surface ( 2 ) of the machine or engine part ( 1 ) and the amorphous hydrocarbon layer ( 5 ).  
   
   
       21 . The process of  claim 20 , wherein at least one intermediate layer ( 4 ) is formed as a metal-containing hydrocarbon layer.  
   
   
       22 . The process of  claim 21 , wherein the metal components of the metal-containing hydrocarbon layer ( 4 ) is at least one member of the group consisting of W, Ti, Hf, Ge and a combination thereof.  
   
   
       23 . The process according of  claim 20  wherein at least one intermediate layer ( 4 ) is formed with a thickness of approximately 0.5 μm to 2.0 μm.  
   
   
       24 . The process of  claim 20  wherein at least one adhesion promoting layer ( 3 ) is formed from at least one member of the group consisting of substances, borides, carbides and nitrides of the transition metals.  
   
   
       25 . The process of  claim 20  wherein at least one adhesion promoting layer ( 3 ) is formed with a thickness of approximately 0.1 μm to 0.5 μm.  
   
   
       26 . The process of  claim 14  wherein the amorphous hydrocarbon layer ( 5 ), at least one intermediate layer ( 4 ) and/or at least one adhesion promoting layer ( 3 ) are deposited at in each case a coating temperature respectively less than the tempering temperature of the machine or engine part ( 1 ).