Amorphous carbon layer for heat exchangers and processes thereof

Abstract

Process for depositing an amorphous carbon layer on substrates, such as heat exchangers, and the coated substrates so formed, such as an aluminum fined heat exchanger.

What is claimed:  
     
         1 . A heat exchanger comprising a heat sink having deposited on its extended surface a layer of an amorphous carbon coating (DLC) having a hardness of at least 2000 Kg/mm 2 , a specific resistivity of at least 10 8  ohm cm, and a dielectric strength of at least 10 6  V/cm.  
     
     
         2 . The heat exchanger of  claim 1  wherein the heat exchanger has extending fins and at least a portion of the fins are coated with the amorphous carbon layer.  
     
     
         3 . The heat exchanger of  claim 2  wherein the fins are made of aluminum.  
     
     
         4 . The heat exchanger of  claim 3  wherein the amorphous carbon layer has a hardness of between about 2000 to about 9000 Kg/mm 2 , a specific resistivity between about 10 8  to about 10 13  ohm cm, and a dielectric strength more than 10 6  V/cm.  
     
     
         5 . The heat exchanger of  claim 4  wherein the thickness of the amorphous carbon is between about 1 to about 6 μm.  
     
     
         7 . The heat exchange of  claim 1  wherein the heat exchanger is selected from the group consisting of aluminum, titanium, molybdenum, silicon and germanium.  
     
     
         8 . The heat exchanger of  claim 1  wherein an intermediate layer is disposed between the surface of the heat exchanger and the amorphous carbon layer and such intermediate layer being a substrate that adheres the amorphous carbon layer to said surface.  
     
     
         9 . The heat exchanger of  claim 8  wherein the amorphous carbon layer has a hardness of between about 2000 to about 9000 Kg/mm 2 , a specific resistivity between about 10 6  to about 10 14  ohm cm, and a dielectric strength more than 10 6  V/cm.  
     
     
         10 . The heat exchanger of  claim 8  wherein the electroplated amorphous carbon has a hardness of between about 2000 to about 9000 Kg/mm 2 , a specific resistivity between about 10 6  to about 10 14  ohm cm, and a dielectric strength more than 10 6  V/cm.  
     
     
         11 . A substrate having on at least a portion of its surface a coated layer of an amorphous carbon layer having a hardness of at least 2000 Kg/μm 2 , a specific resistivity of at least 10 5  ohm 10 8  cm, and a dielectric strength of at least  10   5  V/cm.  
     
     
         12 . The substrate of  claim 11  wherein the substrate material is selected from the group consisting of silicon, germanium, aluminum, titanium, molybdenum, plastics and glasses.  
     
     
         13 . The substrate of  claim 11  wherein an intermediate layer is disposed between the surface of the substrate and the amorphous carbon layer and such intermediate layer being a carbide that adheres the amorphous carbon layer to said surface.  
     
     
         14 . The substrate of  claim 12  wherein the amorphous carbon layer has a hardness of between about 2000 to about 9000 Kg/mm 2 , a specific resistivity between about 10 6  to about 10 14  ohm cm, and a dielectric strength more than 10 6  V/cm.  
     
     
         15 . The substrate of  claim 13  wherein the amorphous carbon layer has a hardness of between about 2000 to about 9000 Kg/mm 2 , a specific resistivity between about 10 6  to about 10 14  ohm cm, and a dielectric strength more than 10 6  V/cm.  
     
     
         16 . The substrate of  claim 11  wherein the amorphous carbon layer has a hardness of between about 2000 to about 9000 Kg/mm 2 , a specific resistivity between about 10 6  to about 10 14  ohm cm, and a dielectric strength more than 10 6  V/cm.  
     
     
         17 . A process for depositing an amorphous carbon layer onto a substrate comprising the steps (a) preparing a plasma vapour deposition chamber; b) pumping into the chamber a carbon containing gas at a pressure range between about 10 −2  and 10 −5  mbar; c) supplying a voltage of at least 1 kV and igniting the gas to provide a self sustain a glow discharge in the gas; and depositing from the carbon containing gas an amorphous carbon layer on said substrate having a hardness of at least 2000 Kg/mm 9 , a specific resistivity of at least 10 8  ohm cm, and a dielectric strength of at least 10 6  V/cm.  
     
     
         18 . The process of  claim 17  wherein the substrate is a heat exchanger.  
     
     
         19 . The process of  claim 8  wherein the amorphous carbon layer has a hardness of between about 2000 to about 9000 Kg/mm 2 , a specific resistivity between about 10 8  to about 10 13  ohm cm, and a dielectric strength more than 10 6  V/cm.  
     
     
         20 . A process for depositing a amorphous carbon layer into a substrate comprising the steps of preparing a PVD system; pumping into the system a carbon containing gas; operating the system at a temperature of at least 150° C. and depositing from the carbon containing gas an amorphous carbon layer on the substrate having a hardness of at least 2000 Kg/mm 2 , a specific resistivity of at least 10 8  ohm cm, and a dielectric strength of at least 10 6  V/cm.