EP1611405A2 - Amorphous carbon layer for heat exchangers - Google Patents
Amorphous carbon layer for heat exchangersInfo
- Publication number
- EP1611405A2 EP1611405A2 EP04759186A EP04759186A EP1611405A2 EP 1611405 A2 EP1611405 A2 EP 1611405A2 EP 04759186 A EP04759186 A EP 04759186A EP 04759186 A EP04759186 A EP 04759186A EP 1611405 A2 EP1611405 A2 EP 1611405A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- amorphous carbon
- substrate
- carbon layer
- layer
- heat exchanger
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 229910003481 amorphous carbon Inorganic materials 0.000 title claims abstract description 26
- 239000000758 substrate Substances 0.000 claims abstract description 20
- 238000000576 coating method Methods 0.000 claims abstract description 19
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 14
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 14
- 239000011248 coating agent Substances 0.000 claims abstract description 12
- 238000000034 method Methods 0.000 claims abstract description 11
- 230000008021 deposition Effects 0.000 claims abstract description 4
- 238000000151 deposition Methods 0.000 claims description 8
- 239000000463 material Substances 0.000 claims description 8
- 239000011521 glass Substances 0.000 claims description 6
- 239000004033 plastic Substances 0.000 claims description 6
- 229920003023 plastic Polymers 0.000 claims description 6
- 229910052732 germanium Inorganic materials 0.000 claims description 5
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 claims description 5
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 4
- 229910052799 carbon Inorganic materials 0.000 claims description 4
- 229910052710 silicon Inorganic materials 0.000 claims description 4
- 239000010703 silicon Substances 0.000 claims description 4
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 3
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 3
- 229910052750 molybdenum Inorganic materials 0.000 claims description 3
- 239000011733 molybdenum Substances 0.000 claims description 3
- 238000005086 pumping Methods 0.000 claims description 3
- 239000010936 titanium Substances 0.000 claims description 3
- 229910052719 titanium Inorganic materials 0.000 claims description 3
- 239000007789 gas Substances 0.000 description 13
- 238000005334 plasma enhanced chemical vapour deposition Methods 0.000 description 8
- 238000000623 plasma-assisted chemical vapour deposition Methods 0.000 description 8
- 239000004215 Carbon black (E152) Substances 0.000 description 5
- 229930195733 hydrocarbon Natural products 0.000 description 5
- 150000002430 hydrocarbons Chemical class 0.000 description 5
- 150000001247 metal acetylides Chemical class 0.000 description 5
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- 150000002500 ions Chemical class 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 3
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 3
- 229910052804 chromium Inorganic materials 0.000 description 3
- 239000011651 chromium Substances 0.000 description 3
- 229910052802 copper Inorganic materials 0.000 description 3
- 239000010949 copper Substances 0.000 description 3
- 239000010432 diamond Substances 0.000 description 3
- 150000002739 metals Chemical class 0.000 description 3
- 239000004065 semiconductor Substances 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 239000002904 solvent Substances 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 238000004378 air conditioning Methods 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 239000000919 ceramic Substances 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 230000002708 enhancing effect Effects 0.000 description 2
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 2
- 229910052737 gold Inorganic materials 0.000 description 2
- 239000010931 gold Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 239000004753 textile Substances 0.000 description 2
- 229910052580 B4C Inorganic materials 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 239000004677 Nylon Substances 0.000 description 1
- 244000089486 Phragmites australis subsp australis Species 0.000 description 1
- 235000014676 Phragmites communis Nutrition 0.000 description 1
- 239000004952 Polyamide Substances 0.000 description 1
- ATJFFYVFTNAWJD-UHFFFAOYSA-N Tin Chemical compound [Sn] ATJFFYVFTNAWJD-UHFFFAOYSA-N 0.000 description 1
- NRTOMJZYCJJWKI-UHFFFAOYSA-N Titanium nitride Chemical compound [Ti]#N NRTOMJZYCJJWKI-UHFFFAOYSA-N 0.000 description 1
- HCHKCACWOHOZIP-UHFFFAOYSA-N Zinc Chemical compound [Zn] HCHKCACWOHOZIP-UHFFFAOYSA-N 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- 238000005513 bias potential Methods 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- INAHAJYZKVIDIZ-UHFFFAOYSA-N boron carbide Chemical compound B12B3B4C32B41 INAHAJYZKVIDIZ-UHFFFAOYSA-N 0.000 description 1
- 150000001721 carbon Chemical class 0.000 description 1
- 239000012159 carrier gas Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000010494 dissociation reaction Methods 0.000 description 1
- 230000005593 dissociations Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 150000002367 halogens Chemical class 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 230000002209 hydrophobic effect Effects 0.000 description 1
- 238000007654 immersion Methods 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000005461 lubrication Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000012299 nitrogen atmosphere Substances 0.000 description 1
- 229920001778 nylon Polymers 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 229920002647 polyamide Polymers 0.000 description 1
- 239000004417 polycarbonate Substances 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 238000004901 spalling Methods 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 230000002459 sustained effect Effects 0.000 description 1
- 229910052725 zinc Inorganic materials 0.000 description 1
- 239000011701 zinc Substances 0.000 description 1
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28F—DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION
- F28F13/00—Arrangements for modifying heat-transfer, e.g. increasing, decreasing
- F28F13/18—Arrangements for modifying heat-transfer, e.g. increasing, decreasing by applying coatings, e.g. radiation-absorbing, radiation-reflecting; by surface treatment, e.g. polishing
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/22—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the deposition of inorganic material, other than metallic material
- C23C16/26—Deposition of carbon only
-
- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
- C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
- C23C16/50—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges
- C23C16/505—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges using radio frequency discharges
- C23C16/509—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating using electric discharges using radio frequency discharges using internal electrodes
Definitions
- the present invention relates generally to surface heat sinks (heat exchangers) having a plurality of fins that effectively increases the surface area thereby enhancing the heat transfer to the air.
- the heat dissipated by convection from the fins on heat exchanger is strongly limited by the thermal barrier of any oxide layer formed on the surface of the fins.
- the roughness of the surface of the fins be increased and/or increase the number of fins or length of the fins thereby enhancing the heat transfer of the air by turbulating the air.
- One problem with turbulating the air is that the pressure drop increase greatly outweighs the increase in heat transfer due to the laws of physics, and hence the limiting factor is fan power and noise under forced convection applications . Under natural convection applications turbulating the airflow may cause the airflow to stall .
- DLC thin amorphous carbon layer
- the sole drawing is a schema of a plasma enhanced chemical vapour deposition system (PECVD) for use in applying a DLC coating on substrates.
- PECVD plasma enhanced chemical vapour deposition system
- the invention in one aspect, relates to a heat exchanger comprising a heat sink having a portion of its surface a thin layer of an amorphous carbon 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 N/cm.
- the thin amorphous carbon layer has properties approaching those of diamonds such as a hardness between about 2000 to 9000 Kg/mm 2 , a specific resistivity between 10 8 to 10 13 ohm cm, and dielectric strength more than 10 6 V/cm.
- Another preferable property of DLC is a low friction of 0.02 in vacuum and less than 0.1 in air.
- the thickness of the DLC layer is preferably in the range of 1 to 5 ⁇ m.
- the DLC layer can be homogeneously deposited and adhere well to metals and semiconductors which form stable carbides. Virtually there is no adhesion on gold, copper, iron but intermediate layers (nickel or some other or material) can be used to solve the problem.
- DLC coatings adheres also on ceramic, glass, poly-carbonate, polyamides (nylon) and on all materials forming carbides (i.e. plastic) that can withstand 150 2 C.
- Preferably DLC coating can have a roughness, as coated, of 0.05 ⁇ m Ra . Basically roughness is the copy of that of the base material coated. Prior to coating, parts should be cleaned either ultrasonically or by immersion cleaning.
- the heat exchanger having extending fins, such as aluminum, copper, or steel with the more preferable being aluminum, and such fins having a DLC film deposited thereon.
- the best way to practice the invention is to remove the oxide layer on the fins and then apply the DLC coating on the surface of the fins .
- any cooled extended surface heat exchanger that uses aluminum fins can be used for car radiators/air conditioning condensers, truck radiators, aircraft heat exchangers, etc. Since most of these types of heat exchanger use turbulators on the fins, a DLC film on the fins may replace the turbulators. This would have an effect of reducing noise as the increase in air pressure drop due to the DLC film being effectively zero. Heat sinks that rely on conduction only of heat to the aluminum fins, i.e.
- the novel amorphous carbon (DLC) layer or coating is an PECVD coating and has the following properties;
- DLC generally adheres well to metals and semiconductors which form stable carbides. Metals including aluminum, titanium and molybdenum have been successfully coated as have the semiconductors, silicon and germanium. There is virtually no adhesion to copper, gold or other metal which do not form carbides, but intermediate layers may be introduced, such as aluminum, zinc, silicon, germanium and other materials that form carbides. Good adhering DLC films have also been deposited on silica, various glasses, titanium nitride and alumina. The bonding strengths of DLC to various plastics are similar to those of films chemically bonded by carbide formation. However, adhesion to plastic must be due to a different mechanism.
- Thicker DLC films may have adhesion problem because of the high compressive stress of about 10 9 Pa.
- films thicker than 2 ⁇ m on germanium may cause spalling problems while films on aluminum have a 50 ⁇ m thickness or larger without any problems because of the plastic flow in the substrate.
- DLC coating is a hard material and has a high cohesive energy, short bond length and a high degree of covalent bonding. DLC hardness is comparable to the conventional PVD and CVD typical materials such as TiN, SiC and Boron Carbide. Hardness can be up to 9000 Kg/mm 2 or higher.
- Coefficient of sliding friction of DLC against a steel ball is in the range of 0.005 - 0.02 under vacuum condition rising to 0.2 under 100% humidity. Dry nitrogen atmosphere is better in friction than dry oxygen. DLC coatings normally shows a high resistance to wear.
- the typical properties of the DLC layer are hardness, low friction, generally chemical inertness, hydrophobic and the amorphous structure contribute to amplify the wear resistance of a hard material.
- DLC is an insulator having a specific resistivity between 10 7 and 10 13 ohm cm. The value decrease when temperature increase. DLC has a high dielectric strength that is generally in the range of more than 10 V/cm.
- DLC coatings can be used on heat sinks but this use is limited to enhancement of solid/ solid heat transfer, that is, transfer between the base of the heat sink and en electronic component.
- the oxide layer of an aluminum fin can be replaced with a highly thermally conductive layer (DLC) so as to reduce the overall resistance to heat transfer, that is the aluminum fins (sheets) will be able to give up heat to the air more effectively.
- DLC highly thermally conductive layer
- Textile reeds, shuttles, healds, needles for mechanical looms, thread guides (ceramic, chromium plated, steel) to improve friction, and for chromium replacement in all the textile operations;
- Chemical small pump pistons, rings, gear pumps parts, bearings '
- Plastic and glass moulding dies
- Automotive clutch pistons, clutch rings, parts for chromium replacement
- Valves ball valves for dry lubrication on soft seated valves ;
- the invention also relates to a process for depositing a thin amorphous carbon layer onto a substrate wherein said layer 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° V/cm; comprising the steps of preparing a plasma vapour deposition chamber; pumping into the chamber a carbon containing gas at a pressure range between about 10 ⁇ 2 and 10 "5 mbar (preferably between 10 "3 and 10 ⁇ 4 mbar) ; supplying a voltage (RF) of at least 1 kV to self sustain a glow discharge as the gas is ignited; depositing an amorphous carbon from the gas onto a substrate in the chamber and removing the coated substrate from the chamber.
- RF voltage
- the sole drawing is coating system for DLC coatings.
- the coating system for DLC thin layer deposition is a Plasma Enhanced Chemical Vapour Deposition (PECVD) that involve the dissociation of hydrocarbon gases (or extremely volatile hydrocarbon solvent) .
- the drawing shows a general schema of the PECVD.
- the system is composed by a vacuum chamber 2 with its vacuum pumping system 4, a multiple gas manifold 6 and a RF power generator 8.
- a gas is introduced in the preferred pressure range 10 "3 - 10 "4 mbar and a RF voltage of one to several thousands is applied, a self sustained glow discharge is ignited. With a DC supply, the smaller electrode is normally connected to the negative terminal 10.
- a dark space forms, across which there is the main potential drop, the plasma assuming a potential close to that of the anode.
- the negative electrode is therefor bombarded with high energy ions.
- a DC supply generally cannot be used if an insulating layer forms on the cathode (as in the case of DLC) .
- the smaller electrode charges negatively because the different mobility of ions and electrons. For a net zero current to flow during the cycle, the smaller electrode becomes negatively charged on average during cycle and is again bombarded by energetic ions.
- a carrier gas containing carbon hydrogen or some halogens is ionized, solid films are deposited on the electrode and this is the PECVD process.
- the growing films are bombarded with ions, probably giving rise to the metastable, mostly amorphous structures of PECVD layers .
- the layers will be dense and hard because weakly bonded atoms will be resputtered.
- hard amorphous hydrogenated carbon films are obtained from hydrocarbon gases.
- process parameters are to be considered: type of gas, gas pressure, gas mixture ratio, substrate temperature, electrode and substrate geometry and electric field frequency. The most important parameters to control are the self bias potential, gas pressure and gas mixture ratio.
- the preferred procedure for producing hard DLC layers consist of first introducing argon at a pressure of 10 " 2 - 10 ⁇ 3 mbar with a RF voltage of about lkV to clean components . Argon is then replaced by a hydrocarbon solvent (highly volatile at low pressure) at a pressure of lO "1 -10 ⁇ " mbar and later mixed with another hydrocarbon gas as discussed above.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Physics & Mathematics (AREA)
- Metallurgy (AREA)
- General Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Engineering & Computer Science (AREA)
- Inorganic Chemistry (AREA)
- Thermal Sciences (AREA)
- Plasma & Fusion (AREA)
- Chemical Vapour Deposition (AREA)
- Laminated Bodies (AREA)
- Physical Vapour Deposition (AREA)
- Cooling Or The Like Of Semiconductors Or Solid State Devices (AREA)
- Cooling Or The Like Of Electrical Apparatus (AREA)
- Carbon And Carbon Compounds (AREA)
Abstract
Process for deposition an amorphous carbon layer on substrates, such as heat exchangers, and the coated substrates so formed, such as an aluminum fined heat exchanger. The heat exchanger comprises a heat sink having deposited on its extended surface a layer of an amorphous carbon coating (DLC) having a hardness of at least 2000Kg/mm2, a specific resistivity of at least 108 ohm cm, and a dielectric strength of at least 106 V/cm.
Description
AMORPHOUS CARBON LAYER
FOR HEAT EXCHANGERS
Field of the Invention
[0001] The present invention relates generally to surface heat sinks (heat exchangers) having a plurality of fins that effectively increases the surface area thereby enhancing the heat transfer to the air.
Background of the Invention
[0002] The heat dissipated by convection from the fins on heat exchanger is strongly limited by the thermal barrier of any oxide layer formed on the surface of the fins. To overcome this limitation, it was suggested that the roughness of the surface of the fins be increased and/or increase the number of fins or length of the fins thereby enhancing the heat transfer of the air by turbulating the air. One problem with turbulating the air is that the pressure drop increase greatly outweighs the increase in heat transfer due to the laws of physics, and hence the limiting factor is fan power and noise under forced convection applications . Under natural convection applications turbulating the airflow may cause the airflow to stall .
Objects of the Invention
[0003] It is an object of the invention to provide a surface area coated with a thin amorphous carbon layer with the properties approaching those of diamonds. [0004] It is another object of the invention to provide an extended surface heat sink with a plurality of aluminum fins coated with a thin amorphous carbon
layer with the properties approaching those of diamonds .
[0005] It is another object of the invention to provide a surface heat sink with a thin amorphous carbon layer coating to be used in industrial • applications such as computer chip cooling, electronic cabinet cooling, car radiators, air conditioning condensers, aircraft heat exchangers and the like.
[0006] It is another object of the invention to provide a process for depositing a thin amorphous carbon layer (DLC) coatings on a wide range of substrates .
Brief Description of the Drawings
[0007] The sole drawing is a schema of a plasma enhanced chemical vapour deposition system (PECVD) for use in applying a DLC coating on substrates.
Summary of the Invention
[0008] The invention in one aspect, relates to a heat exchanger comprising a heat sink having a portion of its surface a thin layer of an amorphous carbon having a hardness of at least 2000 Kg/mm2, a specific resistivity of at least 108 ohm cm, and a dielectric strength of at least 106 N/cm. Preferably the thin amorphous carbon layer has properties approaching those of diamonds such as a hardness between about 2000 to 9000 Kg/mm2, a specific resistivity between 108 to 1013 ohm cm, and dielectric strength more than 106 V/cm. Another preferable property of DLC is a low friction of 0.02 in vacuum and less than 0.1 in air. The thickness of the DLC layer is preferably in the range of 1 to 5
μm. The DLC layer can be homogeneously deposited and adhere well to metals and semiconductors which form stable carbides. Virtually there is no adhesion on gold, copper, iron but intermediate layers (nickel or some other or material) can be used to solve the problem. DLC coatings adheres also on ceramic, glass, poly-carbonate, polyamides (nylon) and on all materials forming carbides (i.e. plastic) that can withstand 1502C. Preferably DLC coating can have a roughness, as coated, of 0.05 μm Ra . Basically roughness is the copy of that of the base material coated. Prior to coating, parts should be cleaned either ultrasonically or by immersion cleaning. Depends on the application, solvent or aqueous cleaner can be used. [0009] Preferably, the heat exchanger having extending fins, such as aluminum, copper, or steel with the more preferable being aluminum, and such fins having a DLC film deposited thereon. The best way to practice the invention is to remove the oxide layer on the fins and then apply the DLC coating on the surface of the fins .
[0010] The heat transfer performance of any cooled extended surface heat exchanger that uses aluminum fins can be used for car radiators/air conditioning condensers, truck radiators, aircraft heat exchangers, etc. Since most of these types of heat exchanger use turbulators on the fins, a DLC film on the fins may replace the turbulators. This would have an effect of reducing noise as the increase in air pressure drop due to the DLC film being effectively zero. Heat sinks that rely on conduction only of heat to the aluminum
fins, i.e. small chip or electronic device heat sinks, would also benefit from this invention, since this is based on heat exchanger design with extended surface heat exchangers in which the heat transfer from the fins to the air being the poorest heat transfer region or greatest resistance to heat transfer (unless working with very high viscosity fluids in pipes or air in pipes) .
[0011] The novel amorphous carbon (DLC) layer or coating is an PECVD coating and has the following properties;
[0012] Adhesion. DLC generally adheres well to metals and semiconductors which form stable carbides. Metals including aluminum, titanium and molybdenum have been successfully coated as have the semiconductors, silicon and germanium. There is virtually no adhesion to copper, gold or other metal which do not form carbides, but intermediate layers may be introduced, such as aluminum, zinc, silicon, germanium and other materials that form carbides. Good adhering DLC films have also been deposited on silica, various glasses, titanium nitride and alumina. The bonding strengths of DLC to various plastics are similar to those of films chemically bonded by carbide formation. However, adhesion to plastic must be due to a different mechanism. Thicker DLC films (more than 6 μm) may have adhesion problem because of the high compressive stress of about 109 Pa. For example, films thicker than 2 μm on germanium may cause spalling problems while films on aluminum have a 50 μm thickness or larger without any problems because of the plastic flow in the substrate.
[0013] Hardness, friction and wear. DLC coating is a hard material and has a high cohesive energy, short bond length and a high degree of covalent bonding. DLC hardness is comparable to the conventional PVD and CVD typical materials such as TiN, SiC and Boron Carbide. Hardness can be up to 9000 Kg/mm2 or higher. Coefficient of sliding friction of DLC against a steel ball is in the range of 0.005 - 0.02 under vacuum condition rising to 0.2 under 100% humidity. Dry nitrogen atmosphere is better in friction than dry oxygen. DLC coatings normally shows a high resistance to wear. The typical properties of the DLC layer, are hardness, low friction, generally chemical inertness, hydrophobic and the amorphous structure contribute to amplify the wear resistance of a hard material.
[0014] Electrical properties . DLC is an insulator having a specific resistivity between 107 and 1013 ohm cm. The value decrease when temperature increase. DLC has a high dielectric strength that is generally in the range of more than 10 V/cm.
[0015] Optical properties. A DLC film 1 μm thick on glass appears dark brown when viewed in transmission. The color comes from a high absorption at the blue end of the spectrum and a low one in the red.
[0016] DLC coatings can be used on heat sinks but this use is limited to enhancement of solid/ solid heat transfer, that is, transfer between the base of the heat sink and en electronic component. Preferably, the oxide layer of an aluminum fin can be replaced with a highly thermally conductive layer (DLC) so as to reduce the overall resistance to heat transfer, that is the
aluminum fins (sheets) will be able to give up heat to the air more effectively.
[0017] Other applications for the DLC coatings are as follows:
Textile: reeds, shuttles, healds, needles for mechanical looms, thread guides (ceramic, chromium plated, steel) to improve friction, and for chromium replacement in all the textile operations; Chemical: small pump pistons, rings, gear pumps parts, bearings '
Plastic and glass: moulding dies;
Automotive: clutch pistons, clutch rings, parts for chromium replacement;
Valves : ball valves for dry lubrication on soft seated valves ;
Surgical instruments, manufacturing machinery and window/glass coatings.
[0018] The invention also relates to a process for depositing a thin amorphous carbon layer onto a substrate wherein said layer having a hardness of at least 2000 Kg/mm2, a specific resistivity of at least 108 ohm cm, and a dielectric strength of at least 10° V/cm; comprising the steps of preparing a plasma vapour deposition chamber; pumping into the chamber a carbon containing gas at a pressure range between about 10~2 and 10"5 mbar (preferably between 10"3 and 10~4 mbar) ; supplying a voltage (RF) of at least 1 kV to self sustain a glow discharge as the gas is ignited; depositing an amorphous carbon from the gas onto a substrate in the chamber and removing the coated substrate from the chamber.
Description of the Preferred Embodiment [0019] The sole drawing is coating system for DLC coatings. Specifically, the coating system for DLC thin layer deposition is a Plasma Enhanced Chemical Vapour Deposition (PECVD) that involve the dissociation of hydrocarbon gases (or extremely volatile hydrocarbon solvent) . The drawing shows a general schema of the PECVD. The system is composed by a vacuum chamber 2 with its vacuum pumping system 4, a multiple gas manifold 6 and a RF power generator 8. When a gas is introduced in the preferred pressure range 10"3 - 10"4 mbar and a RF voltage of one to several thousands is applied, a self sustained glow discharge is ignited. With a DC supply, the smaller electrode is normally connected to the negative terminal 10. Between this electrode 10 and the plasma 12, a dark space forms, across which there is the main potential drop, the plasma assuming a potential close to that of the anode. The negative electrode is therefor bombarded with high energy ions. A DC supply generally cannot be used if an insulating layer forms on the cathode (as in the case of DLC) . With RF the smaller electrode charges negatively because the different mobility of ions and electrons. For a net zero current to flow during the cycle, the smaller electrode becomes negatively charged on average during cycle and is again bombarded by energetic ions. With a carrier gas containing carbon, hydrogen or some halogens is ionized, solid films are deposited on the electrode and this is the PECVD process. The growing films are bombarded with ions, probably giving rise to the metastable, mostly amorphous structures of PECVD layers . The layers will
be dense and hard because weakly bonded atoms will be resputtered. With this technique, hard amorphous hydrogenated carbon films are obtained from hydrocarbon gases. Several process parameters are to be considered: type of gas, gas pressure, gas mixture ratio, substrate temperature, electrode and substrate geometry and electric field frequency. The most important parameters to control are the self bias potential, gas pressure and gas mixture ratio. The preferred procedure for producing hard DLC layers consist of first introducing argon at a pressure of 10" 2 - 10~3 mbar with a RF voltage of about lkV to clean components . Argon is then replaced by a hydrocarbon solvent (highly volatile at low pressure) at a pressure of lO"1 -10~" mbar and later mixed with another hydrocarbon gas as discussed above.
[0020] Those skilled in the art will recognize that changes may be made without departing in the scope or spirit from the present invention as more particularly defined in the claims below. For example, if the process requires a temperature exceeding 2002C, then a PVD procedure can be used.
Claims
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 2000Kg/mm2, a specific resistivity of at least 108 ohm cm, and a dielectric strength of at least 10δ 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, and wherein the fins are made of aluminum.
3. The heat exchanger of claim 1 wherein the amorphous carbon layer has a hardness of between about 2000 to about 9000 Kg/mm2, a specific resistivity between about 108 to about 1013 ohm cm, and a dielectric strength more than 10s V/cm, and wherein the thickness of the amorphous carbon is between about 1 to about 6 μm, and wherein the heat exchanger is selected from the group consisting of aluminum, titanium, molybdenum, silicon and germanium.
4. 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, and wherein the amorphous carbon layer has a hardness of between about 2000 to about 9000 Kg/mm2, a specific resistivity between about 10 to about 10 ohm cm, and a dielectric strength more than 106 V/cm.
5. 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/μm2, a specific resistivity of at least 105 ohm 108 cm, and a dielectric strength of at least 105 V/cm.
6. The substrate of claim 5 wherein the substrate material is selected from the group consisting of silicon, germanium, aluminum, titanium, molybdenum, plastics and glasses.
7. The substrate of claim 5 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 .
8. The substrate of claim 5 wherein the amorphous carbon layer has a hardness of between about 2000 to about 9000 Kg/mm2, a specific resistivity between about 106 to about 1014 ohm cm, and a dielectric strength more than 10δ V/cm.
9. 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 IkV 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/mm9, a specific resistivity of at least 108 ohm cm, and a dielectric strength of at least 10s V/cm.
10. The process of claim 9 wherein the substrate is a heat exchanger.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US10/410,211 US20040200599A1 (en) | 2003-04-10 | 2003-04-10 | Amorphous carbon layer for heat exchangers and processes thereof |
| PCT/US2004/010619 WO2004092672A2 (en) | 2003-04-10 | 2004-04-08 | Amorphous carbon layer for heat exchangers |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| EP1611405A2 true EP1611405A2 (en) | 2006-01-04 |
Family
ID=33130753
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP04759186A Withdrawn EP1611405A2 (en) | 2003-04-10 | 2004-04-08 | Amorphous carbon layer for heat exchangers |
Country Status (7)
| Country | Link |
|---|---|
| US (1) | US20040200599A1 (en) |
| EP (1) | EP1611405A2 (en) |
| JP (1) | JP2006526075A (en) |
| CN (1) | CN1802881A (en) |
| BR (1) | BRPI0409103A (en) |
| NO (1) | NO20055165L (en) |
| WO (1) | WO2004092672A2 (en) |
Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4423989B2 (en) * | 2004-02-05 | 2010-03-03 | トヨタ自動車株式会社 | Thermoelectric generator for internal combustion engine |
| TWI268755B (en) * | 2005-03-21 | 2006-12-11 | Mitac Tech Corporation | Chip heat dissipation system and manufacturing method and structure of heat exchange device thereof |
| US7352584B1 (en) | 2005-05-10 | 2008-04-01 | Chien-Min Sung | Diamond-like carbon coated devices |
| CN1870863B (en) * | 2005-05-28 | 2011-06-08 | 鸿富锦精密工业(深圳)有限公司 | Casing of portable electronic device and its manufacturing method |
| JP4735309B2 (en) * | 2006-02-10 | 2011-07-27 | トヨタ自動車株式会社 | Cavitation erosion resistant member and method of manufacturing the same |
| CN100412228C (en) * | 2006-06-08 | 2008-08-20 | 哈尔滨工业大学 | Combination strengthening treatment method of ion implantation and deposition on aluminum or aluminum alloy substrate surface |
| US7968473B2 (en) * | 2006-11-03 | 2011-06-28 | Applied Materials, Inc. | Low temperature process for depositing a high extinction coefficient non-peeling optical absorber for a scanning laser surface anneal of implanted dopants |
| TW201020336A (en) * | 2008-11-20 | 2010-06-01 | Yu-Hsueh Lin | Method for plating film on surface of heat dissipation module and film-plated heat dissipation module |
| CN101736312B (en) * | 2008-11-26 | 2012-11-21 | 林玉雪 | Surface coating method of cooling module |
| CN103890937B (en) * | 2011-10-20 | 2017-05-03 | 科卢斯博知识产权有限公司 | Bulk amorphous alloy heat sink |
| DE102018101453A1 (en) * | 2018-01-23 | 2019-07-25 | Borgwarner Ludwigsburg Gmbh | Heating device and method for producing a heating rod |
| WO2019145795A2 (en) | 2018-01-26 | 2019-08-01 | Cellink Ab | Systems and methods for optical assessments of bioink printability |
| US11186736B2 (en) | 2018-10-10 | 2021-11-30 | Cellink Ab | Double network bioinks |
| WO2020157077A2 (en) * | 2019-01-28 | 2020-08-06 | Cellink Ab | A compact fluorescence microscope and a cell monitoring system |
| US11826951B2 (en) | 2019-09-06 | 2023-11-28 | Cellink Ab | Temperature-controlled multi-material overprinting |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0344485A (en) * | 1989-07-12 | 1991-02-26 | Matsushita Refrig Co Ltd | Fin material for heat exchanger |
| US5031029A (en) * | 1990-04-04 | 1991-07-09 | International Business Machines Corporation | Copper device and use thereof with semiconductor devices |
| EP0552475B1 (en) * | 1992-01-23 | 1997-09-10 | Siemens Aktiengesellschaft | Semiconductor module with high insulating and heat dissipating capability |
| US5840427A (en) * | 1996-05-21 | 1998-11-24 | Teledyne Industries Incorporated | Method for making corrosion resistant electrical components |
| US6131533A (en) * | 1996-08-15 | 2000-10-17 | Citizen Watch Co., Ltd. | Jig for forming hard carbon film over inner surface of guide bush using the jig |
| US5981000A (en) * | 1997-10-14 | 1999-11-09 | International Business Machines Corporation | Method for fabricating a thermally stable diamond-like carbon film |
| US6301333B1 (en) * | 1999-12-30 | 2001-10-09 | Genvac Aerospace Corp. | Process for coating amorphous carbon coating on to an x-ray target |
| US6713179B2 (en) * | 2000-05-24 | 2004-03-30 | Guardian Industries Corp. | Hydrophilic DLC on substrate with UV exposure |
| JP2002228391A (en) * | 2001-01-30 | 2002-08-14 | Daikin Ind Ltd | Air heat exchanger with fins |
| US6788841B2 (en) * | 2002-01-16 | 2004-09-07 | Genvac Corporation | Diamond-like carbon heat sink for reflective optical switches and devices |
| US6891324B2 (en) * | 2002-06-26 | 2005-05-10 | Nanodynamics, Inc. | Carbon-metal nano-composite materials for field emission cathodes and devices |
-
2003
- 2003-04-10 US US10/410,211 patent/US20040200599A1/en not_active Abandoned
-
2004
- 2004-04-08 JP JP2006509754A patent/JP2006526075A/en not_active Abandoned
- 2004-04-08 EP EP04759186A patent/EP1611405A2/en not_active Withdrawn
- 2004-04-08 WO PCT/US2004/010619 patent/WO2004092672A2/en not_active Ceased
- 2004-04-08 CN CN200480015652.7A patent/CN1802881A/en active Pending
- 2004-04-08 BR BRPI0409103-5A patent/BRPI0409103A/en not_active IP Right Cessation
-
2005
- 2005-11-03 NO NO20055165A patent/NO20055165L/en not_active Application Discontinuation
Non-Patent Citations (1)
| Title |
|---|
| See references of WO2004092672A3 * |
Also Published As
| Publication number | Publication date |
|---|---|
| NO20055165L (en) | 2005-11-03 |
| CN1802881A (en) | 2006-07-12 |
| BRPI0409103A (en) | 2006-04-04 |
| WO2004092672A3 (en) | 2004-12-23 |
| US20040200599A1 (en) | 2004-10-14 |
| JP2006526075A (en) | 2006-11-16 |
| WO2004092672A2 (en) | 2004-10-28 |
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