FI120051B - Method of connecting metal powder to a heat transfer surface and heat transfer surface - Google Patents

Description

METHOD FOR CONNECTING METALLIC POWDER TO THERMAL TRANSFER SURFACE AND HEAT TRANSFER SURFACE

FIELD OF THE INVENTION

The purpose of the developed method is to form a porous surface layer on the heat transfer surface that can be firmly bonded to the underlying surface at a temperature and time suitable for industrial production. The heat transfer surface is copper or copper alloy, preferably non-oxygenated or phosphorus deoxidized copper. The powder forming the porous surface is 10 finely divided copper powders or copper alloy powders. In the method of the invention, brazing is applied to the heat transfer surface to bind the copper powder to its substrate. The solder preferably contains nickel, tin and phosphorus alloyed with copper. The invention also relates to a heat transfer surface having a porous surface formed by means of copper or copper alloy powder and brazing.

BACKGROUND OF THE INVENTION

The development of heat exchangers has always been focused on the heat transfer surface. ***. to get the maximum heat transfer capacity. First • · • · · . . ·. The development stage can be considered, for example, when thinking about a smooth surface.

• · ·

The second generation in development is the appearance of differently grooved and fluted surfaces, whereby the pattern can be on both the inner and outer surfaces of the tubes. In recent years, the third generation of heat transfer surfaces, porous surfaces, has been developed. The porous surface is formed by depositing a finely divided powder on the heat transfer surface, which is attached to the heat exchange surface in various ways.

: T: Powder forms a porous layer on the surface of a pipe or other heat exchanger that allows the • heat transfer capacity to be increased.

The increase in heat transfer capacity is based on the fact that the porous surface. 30 boiling begins at a lower temperature than normal. When # · • · ·. ·: Starts at a lower temperature than normal, the temperature difference between the heat transfer surface and the liquid becomes smaller.

2

For example, when using water as a liquid, the temperature must not rise to 100 degrees Celsius, because then it is no longer a matter of the intended bubble boiling on the porous surface, but then the whole liquid boils.

Heat transfer surfaces on which the porous surface can be used include, for example, heat exchanger tubes, which can be provided with a porous layer on both the outside and the inner surface. In addition, heat transfer devices include heat sink, heat spreader, heat pipette and vapor chamber, boiling surfaces for cooling electronic components, as well as solar panels, heat sinks, car radiators, and other coolers such as pouring ducts and water coolers.

U.S. Patent Nos. 3,821,018 and 4,064,914 describe the formation of a porous metal layer on a copper surface. The metallic layer 15 is formed of copper, steel or copper alloy powder, bonding powder and an inert liquid binder. The bonding metal alloy powder comprises either a powder containing 90.5-93% by weight of copper and 7-9.5% by weight of phosphorus, a powder containing 25-95% by weight of antimony and the remainder of copper or powder, ··· . with 56% silver, 22% copper, 17% zinc and 5% tin. Both • ·. *! *. The size of the 20 porous surface forming powder that the joint powder has is · · · ···: ·. between 32-500 µm, and the amount of bonding powder 10-30% of the total amount of powder.

• · ·. * ··. The surface on which the porous layer is formed is first coated with a binder. A uniform layer of ·· «· copper powder and bonding powder is then applied over the binder. The piece is first heated to below 538 ° C under non-oxidizing conditions to evaporate the binder. The temperature is increased at a rate of about 200 ° C / h. In the second · · · · heating step, the temperature is raised faster to 732-. ! ·. 843 ° C. At this temperature, the bonding powder melts and solders • · ·. ···. powder pulp to the substrate.

JP patent application 61228294 discloses a method of forming a porous surface on the inner surface of a heating pipe. First, • · 3 binder is applied to the pipe surface. The porous surface is then formed of metal particles of the order of 100 to 300 µm. As the fluxing agent, for example, tin chloride can be used, which is sprayed onto the powder layer and dried to remove the binder. If multiple layers are desired, 5 operations are performed more than once. Finally, the powder is firmly attached to the tube surface by solder. The solder used is tin or tin * lead alloy. The soldering temperature is 300-350 ° C.

JP patent application 2175881 describes the formation of a powdered material layer on the inner surface of a heat transfer tube. The tube is copper or aluminum. With the aid of a suitable binder or flux, a uniform layer of a mixture of two powders is formed on the inner surface of the tube. One of the powders is a metal having a low melting point such as tin and the other having a higher melting point such as copper. The powders 15 have a grain size of 0.01 to 3 mm. In addition, a spiral groove is formed on the inner surface of the tube. The tube is heated to a melting point of powder having a lower melting point, whereby the powder melting at a higher temperature also adheres to the surface of the tube. At the same time the surface of the pipe. a stable porous layer is formed.

Low Temperature is disclosed in U.S. Patent Application No. 1449880; ···. a sintering process to form a porous surface on the surface of the tube. Accordingly, a glue is applied to the surface of the tube, followed by an injection of copper-tin-powder mixture into a furnace, where it is treated with shielding gas. In the first step, the tube is maintained at 400-500 ° C for 5 to 30 minutes, after which the temperature is rapidly raised to 670-700 ° C, at which temperature the tube is maintained at 60 ° C. 90 min The powder mixture has a tin content of 9-13% by weight.

The above-mentioned U.S. Patents 3,821,018 and 4,064,914 disclose success. A method in which a finely divided powder is bonded to a heat transfer surface using a binder and bonding powder. The binder is removed by slow heating 4, after which the temperature is raised to at least 732 ° C to melt and solder the bonding powder to the heat transfer surface. This is brazing, where the required heating temperature is high and the heating time is long to be realized on a production scale.

5

The limitation of the use of silver-containing solder is the higher melting and soldering temperature and price. Other prior art methods employ tin or a tin alloy to attach the powder to the heat transfer surface by soldering. As is known, the strength of a soft-soldered ίο joint is significantly lower than that of a brazed joint. Fluid flowing through the heat transfer surface may, in long term use, release powder particles from the heat transfer surface if the bond between the powder particles is weak. The result is a decrease in the heat transfer capacity of the body. Some of the methods described above utilize 15 separate fluxes, which necessitates the removal of flux residues as a separate step to prevent corrosion.

PURPOSE OF THE INVENTION

... # The purpose of the developed method is to form a porous surface layer on the heat transfer surface, which can be firmly bonded to the surface below at a temperature and time suitable for industrial production.

• · · • · · · ·

SUMMARY OF THE INVENTION

• · · ·. ···. The invention relates to a method for forming a highly adherent porous ·· · 25 surface layer on a heat transfer surface. The heat transfer surface is ··· copper or copper alloy, preferably non-oxidized or phosphorus deoxidized copper. The powder forming the porous surface is finely divided copper · · ·. * 1. powder or copper alloy powder. In the method of the invention, the · · ·. ***. brazing, preferably containing nickel, • tin and phosphorus in copper alloy, is introduced into the heat transfer surface. To perform brazing, the heat transfer surface is subjected to a heat treatment at a maximum temperature of 725 ° C.

• · · 5

The solder layer can be applied to the heat transfer surface in a variety of ways, and thereafter or simultaneously a powder forming the actual porous surface is applied to the surface. The powder particles 5 forming the porous surface are soldered to each other and annealed to the heat transfer surface serving as the substrate.

«

The invention also relates to a heat transfer surface of copper or copper alloy formed on a porous surface of copper or copper alloy powder by brazing containing Ni-Sn-P-Cu.

io

The essential features of the invention will be apparent from the appended claims.

The heat transfer surface to which the porous surface layer is attached is preferably 15 non-oxygenated or phosphorus deoxidized copper having a phosphorus content of the order of 150-400 ppm, i.e. the heat transfer capacity of the material is inherently very high. The prior art describes how many other devices are considered as heat transfer surfaces in addition to heat exchanger tubes. The process of our invention for producing a permanent porous surface, as well as the heat transfer surface of the invention, can be used in the manufacture of these devices.

• ·· • «· • · · · · · ·

The brazing agent used in the process and product of the invention is • · · ·. ···. an alloy containing nickel, tin and phosphorus in addition to copper.

Concentrations of solder alloy are preferably in the range: 0.8-5.2% by weight: ·% Ni, 0-27.4% by weight Sn, 2.2-10.9% by weight P with copper remaining . The composition of a solder which has been found to be advantageous has the following composition: 3.9 -4.5 wt% Ni, · · ·. 1 ·. 14.6-16.6 wt% Sn, 5.0-5.5 wt% P, the remainder being copper. Used solder • · ·. ···. the amount is 1-50% by weight of the amount of powder applied to the entire heat transfer surface.

Preferably, the solder has a melting point in the range of 590 ° C to 605 ° C.

• ♦ • • • · 6 6 6 6 6 6

In order to obtain a porous surface, a finely divided copper or copper alloy powder having a relatively narrow particle size distribution and preferably having a powder or particle shape is introduced into the heat transfer surface. Due to the narrow particle size distribution, a large amount of pores remain in the coating where the heat transfer fluid begins to boil at low temperatures.

The grain size distribution may be, for example, a narrow range of 35 to 500 µm, preferably 35 to 300 µm. One preferred grain size range is 37-90 µm. If the grain size distribution is large, the coating may become too tight and the benefits of the porous surface will be lost.

The heat transfer surface may be treated with a binder, or the binder may be mixed with the metal powders used to make the coating, as described in the prior art, but is not necessary. If the binder is used, it is removed by annealing according to the prior art.

Solder powder can be applied to the heat transfer surface in several different ways. According to a method according to the invention, the solder powder is mixed with copper powder. This method is especially possible if you want to use * ♦ 20 separate binders. For simplicity, the powder used to form the porous surface is called copper powder, • ··] ···. although it may also be copper alloy powder. According to another method, the solder layer is applied to the heat transfer surface before the copper powder is applied! ···. To it. The solder can be applied to the heat transfer surface, such as binder, · · ·· · 25 before the copper powder is applied. bring: · · · ·: ***: Copper powder to the surface Solder powder can also be applied to the heat transfer surface by ··· # thermal spraying or by brushing or spraying gas • • · · · · solder powder mixed with a binder.

The copper powder forming the actual porous surface can also be fed to the heat transfer surface in a number of ways. One way is to mix 7 binder, solder powder and copper powder and spray the mixture on the heat transfer surface. is applied to the surface of the material to be treated and the copper powder is sprayed onto the solder layer, preferably having a thickness of the order of 35 to 500 µm and preferably of 35 to 300 µm.

It is preferable to carry out heat treatment of the heat transfer surface in the shielding gas to prevent the oxidation of the copper. Commonly used gases or gas mixtures such as argon, nitrogen, hydrogen, nitro-hydrogen, carbon monoxide or cracked ammonia may be used as the shielding gas. For drying / evaporating the binder, treatment at about 300 to 400 ° C is sufficient. Strong soldering between the powder particles and the heat transfer surface is obtained when the article to be treated is momentarily, for 1 to 10 minutes, at a temperature of up to 725 ° C, preferably in the range of 650-700 ° C. The solder material may then be molten 15 or wood-like. For example, a batch furnace or a pass-through furnace may be used as the furnace through which a piece comprising the heat transfer surface is passed. When the body is only momentarily at that temperature, it means a clear energy saving over the prior art. Also momentary: * ··; In practice, heating also means that the oven used can be • t ·: 20 relatively short, reducing investment costs.

***: It has been shown that brazing used in the process according to the invention forms a strong bond between the heat transfer surface and the copper powder [[[:] particles and binds the particles together. . Since the solder 25 of the invention does not require a separate flux, the flux waste removal step is also eliminated. The solder does not contain any toxic ingredients • · ♦ such as lead, so a discarded product containing a heat transfer surface: can be recycled without risk and used in the manufacture of a new equivalent product ···.

• · · 30 • · • ·. ·· *. The invention also relates to a heat transfer surface of copper or copper alloy formed by a porous surface of copper or copper alloy powder 8 by brazing with Cu-Ni-Sn-P. In addition to heat exchanger tubes, the heat transfer surface may be formed in other heat transfer devices including heat sink, heat spreader, heat pipe and vapor chamber and boiling surfaces for cooling electronic components, as well as solar panels, heat sinks, car radiators and the like. various casting molds and casting coolers.

LIST OF FIGURES

Figure 1 is an enlarged view of the porous heat transfer surface of Example 1, Figure 2 is a sectional view of the surface of a porous copper tube prepared according to Example 1, and Figure 3 is a view of the heat transfer and .

EXAMPLES

: ***: Example 1 • · ·: 20 Copper deoxidized copper strip (Cu-DHP) was used as the heat transfer surface. The copper powder was a water atomized powder with a copper content of 99.86% and a grain size in the range of 37-90 µm. The soldering powder used was a powder of the composition: 3.9 -4.5 wt% Ni, 14.6-16.6 wt% Sn, 5.0-5.5 wt% ···% - the rest being copper. The solder powder had a spherical shape and a grain size slightly smaller than the copper powder. The soldering powder has a melting range of ·· *: * 593-604 ° C. Both powders were mixed with a commercial organic «·· • · * ··· * binder to form a powder paste. The composition of the paste by weight was 77% copper powder, 18% binder and 5% solder powder.

··· • · · · ···: * · *: 30 The paste was sprayed onto the copper strip. The sprayed coating layer had a thickness of about 100 µm. The strip was passed through resistors acting as drying and soldering furnaces at a speed of 10 cm / min. The temperature of the binder drying and evaporation furnaces was about 300 ° C and that of the soldering furnace about 700 ° C. The shielding gas was a nitrogen atmosphere with some hydrogen present to prevent the body from oxidizing.

5 After soldering, the tape was subjected to an inspection which found that the powder particles had adhered firmly to the tape surface and to each other. The tape could also be bent without loosening the powder from the surface. The surface porosity and surface area were large and the structure had numerous channels extending from the surface of the strip to the surface of the powder layer, as shown in Figures 1 and 2. Figure 1 is a SEM image of a porous heat transfer surface made of Scanning Electron Microscopy and Figure 2 is a microscopic view of a cross-section of a porous copper tube.

Figure 3 shows the heat transfer capacity of a porous copper tube of Example 15 prepared as described in Example 1 as a function of the temperature difference (Ts - Tlq) between the surface (q) and the liquid (pentane) compared to the smooth and fluted surface.

. ···. After forming the porous surface, the strip was welded into a tube so that • «·; The 20 porous surface formed the inner surface of the tube. The welding was quite successful despite the porous surface ··· · * · .. The internal surface of the finished heat transfer tube: 1: The porosity of the coating was about 40% by volume.

»· · · · · · · · · · · · · · · · · · · ··· ·••••••••••••••••••••••••••••••••••••••••

Claims (23)

A process for forming a highly adherent porous surface layer on a copper or copper alloy heat transfer surface, wherein the 5 porous layer is formed from a copper or copper alloy powder, characterized in that the copper or copper alloy powder is tightly bonded to The transfer surface is led to a brazing heat treatment up to a maximum temperature of 725 ° C. Process according to Claim 1, characterized in that the composition of the brazing alloy is in the range 0.8-5.2% by weight Ni, 0-27.4% by weight Sn, 2.2-10.9% by weight P, the remainder being copper. 15 3. Förfarande enligt patent krav 1 eller 2, kännetecknat av att härdlodslegeringens mosses and ligger inom omrädet 3.9-4.5 vic-% Ni, 14.6-16.6 vic-% Sn, 5.0-5.5 vic- % P och resten koppar och dess smelttemperatur 590-605 ° C. 5 The process according to claim 1 or 2, characterized in that the composition of the brazing alloy is in the range of 3.9 to 4.5 wt% Ni, 14.6 to 16.6 wt% Sn, 5.0 to 5.5 wt% % P with the remainder being copper, and having a melting point. * ··. temperature is 590-605 ° C. ♦ · ♦. The process according to any one of claims 1 to 3, characterized in that: ***: the amount of brazing alloy is from 1 to 50% by weight of the amount of powder used to form the entire porous surface. • · · • · · · · · 4. Förfarande enligt face av patentkraven 1-3, kännetecknat av att toyden härdlodslegering utgör 1-50 vikt-% av hela den powder play som används för bildande av en porös yta. ίο 5. Förfarande enligt vorte av patentkraven 1- 4, kännetecknat av att härdlodslegeringen päförs Värmeöverföringsytan i pulverform tillsammans med koppar- och kopparlegeringspulvret. The process according to any one of claims 1 to 4, characterized in that the brazing alloy is introduced into the heat transfer surface in powder form together with a copper or copper alloy powder. • · · • · · ··· 6. Förfarande enligt patentkrav 5, kännetecknat av att av härdlodspulver, 15 koppar-eller kopparlegeringspulver-picture med bindemedel en paste som sprutas eller strüs Päveröverföringsytan. A method according to claim 5, characterized in that • · ·: ·! ·. 30 · brazing, copper or copper alloy powders are formed • · • ·. ···. with binder paste to be sprayed or brushed onto the heat transfer surface. 7. Förfarande enligt nägot av patentkraven 1-4, kännetecknat av att. ···. härdlodslegeringen päförs värmeöverföringsytan genom att doppa • · 20 Värmeöverföringsytan i lodsmältan. • · * ··· • · · · · « Method according to one of Claims 1 to 4, characterized in that the brazing alloy is introduced into the heat transfer surface by dipping the heat transfer surface into the solder melt. 5 8. Förfarande enligt nägot av patentkraven 1-4, kännetecknat av att «M ··· härlodslegeringen päförs Värmeöverföringsytan genome therm · ····: ***: sprutning. • · · 25: T: 9. Förfarande enligt face av patentkraven 1-4, kännetecknat av att av [* · härdlodspulver och bindemedel bildas en pasta som sprutas eller stryks: * ··. headquarters. • · • · · • $ ···. ···. 30 10. Förfarande enligt nägot av patentkraven 1-9, kännetecknat av att • ·: härdlödningen genomförs vid en tempur av 650- 700 ° C. • · Method according to one of Claims 1 to 4, characterized in that the brazing alloy is applied to the heat transfer surface by thermal injection. Method according to one of Claims 1 to 4, characterized in that the brazing powder and the binder are made into a paste which is sprayed or brushed onto a heat transfer surface. Process according to one of Claims 1 to 9, characterized in that the brazing is carried out at a temperature of 650 to 700 ° C. Method according to one of Claims 1 to 10, characterized in that the heat transfer surface is maintained at a soldering temperature of 1-10 min. The process according to any one of claims 1 to 11, characterized in that the copper or copper alloy powder forming the porous surface: ***: the particle size distribution is narrow and selected from the range 35 - 500 pm. · · · · · · · · · · 11. Förfarande enligt face av patentkraven 1-10, kännetecknat av att color-verföringsytan hälls vid loudningstemperaturen under 1-10 min. 12. Förfarande enligt face av patentkraven 1-11, kännetecknat av att 5 particleelstorleksfördelningen hos kopparlarer kopparlegeringspulvret som bildar en pores smal och har roll inom omräd 35-500 pm. 13. Förfarande enligt patentkrav 12, kännetecknat av att partikelstorleksfördelningen hos kopparlerer kopparlegeringspulvret som bildar en ίο dusty har roll inom omrädet 35-300 pm. The method according to claim 12, characterized in that the grain size distribution of the copper or copper alloy powder forming the porous surface is in the range of 35 to 300 µm. The process according to claim 12 or 13, characterized in that the copper or copper alloy powder forming the porous surface: ·! ·. The grain size range is 30 to 90 µm. • ♦ • · «« «•« • · 14. Förfarande enligt patent krav 12 eller 13, kännetecknat av att particle blocker lexomädet hos kopparlerer kopparlegeringspulvret som bildar en dusty at 37-90 pm. 15. Förfarande enligt face av patentkraven 1-14, kännetecknat av att Värmeöverföringsytan harildats competent to apply kopparlager kopparlegeringsband. • · · • · • 20 16. Förfarande enligt patentkrav 15, kännetecknat av att av koppar- eller • · · kopparlegeringsbandet har genom svetsning framställts ett • · ·. ···. Värmeväxlings-rör stem inre eller yttre yta bildar en värvmeöverföringsyta. • · · • · · · · ·: * ··. 17. Värmeöverföringsyta av koppar eller kopparlegeringering flowing picture that • · · 25 dusty ytskikt av koppar- eller kopparlegeringspulver, kännetecknad av: att förbindningen av koppar- eller kopparlegeringspulvret fast vid • · · ·: * * en härdlodslegering. ! ·. som innehäller nickel, tenn och phosphorus legerade med koppar och ·· «. ···. förbindningen av det porösa ytskiktet med värmeöverföringsytan har ··· 30 genomförts vid en tempur av högst 725eC. • · · «· • · Method according to one of Claims 1 to 14, characterized in that the heat transfer surface is formed on the surface of a copper or copper alloy strip. Method according to Claim 15, characterized in that the copper or copper alloy strip has a heat exchanger tube made by welding, the inner or outer surface of which forms a heat transfer surface. 17. A heat transfer surface of copper or copper alloy with a porous surface layer of copper or copper alloy powder, characterized in that the copper or copper alloy powder is tightly bonded to the heat transfer surface by a brazing alloy containing nickel, tin and phosphorus alloy, bonding to the heat transfer surface is performed at a temperature of up to 15,725 ° C. 18. Värmeöverföringsyta enligt patentkrav 17, a transducer of an attachment for a bildande av en porous use of hardlodslegeringens mosses and ligand inom omrädet 0.8-5.2 vikt-% Ni, 0-27.4 vikt-% Sn, 2,2-10 , 9 vikt-% P och resten koppar. 5 Heat transfer surface according to claim 17, characterized in that a brazing alloy is used to form the porous surface. the composition is in the range 0.8-5.2% by weight Ni, 0-27.4% by weight Sn, 2.2- • · ·: 10.9-9% P with the remainder being copper. • · · • · • ♦ • · · 19. Värmeöverföringsyta enligt patent krav 17 eller 18, kännetecknad av att den för bildande av en porosity of the hardlodslegeringens moss system and ligand inom omdates 3.9-4.5 vic% Ni, 14.6-16.6 vic% Sn, 5, 0-5.5 wt-% P och resten koppar och dess smälttemperatur är 590-605 eC. A heat transfer surface according to claim 17 or 18, characterized in that the brazing alloy used to form the porous surface has a composition in the range of 3.9% to 4.5% by weight Ni, 14.6% to 16.6% by weight. % Sn, 5.0-5.5 wt% P, the remainder being copper, and a melting point of 590-605 ° C. A heat transfer surface according to any one of claims 17 to 19, characterized in that the amount of hard solder alloy used to form the porous surface is 1-50% by weight of the total porous surface. ·· *. the amount of powder used to form it. · · · 20. Värmeöverföringsyta enligt face av patentkraven 17-19, kännetecknad av att playden av härdlodslegering som använts för bildande av en porös yta utgör 1-50 vikt-% av hela den pulvermängd 15 som använts för bildande av den porösa ytan. 21. Värmeöverföringsyta enligt nägot av patentkraven 17-20, kännetecknad av att den porösa Värmeöverföringsytan har bildats nap ... ytan av ett koppar- eller kopparlegeringsband. • · • · 20 • · · · · · Heat transfer surface according to one of claims 17 to 20, characterized in that the porous heat transfer surface is formed on the surface of a copper or copper alloy strip. 5 Heat transfer surface according to Claim 21, characterized in that the copper or copper alloy strip has a heat exchanger tube formed by welding, the inner and / or outer surface of which is porous. A heat transfer surface according to any one of claims 17 to 22, characterized in that the porous heat transfer surface is formed of a group of devices comprising heat zinc, heat spreader, heat pipette and vapor chamber, boiling surfaces for cooling electronic components, solar panels, cooling elements, 15 car radiators and other radiators such as various casting kits and spill coolers. ··· • · • · 20 1. Förfarande för att bilda et stadigt vidhäftande, poröst ytskikt päen • · ·: · *. * Värmeöverföringsyta av koppar eller kopparlegering, varvid det porösa • · ·! ···. skiktet pictures av koppar- eller kopparlegeringspulver, kännetecknat av • · · att förbindningen av koppar- eller kopparlegeringspulvret fast vid • · · ·: ***; genomförs the heat transfer surface by means of a härdlodslegering • · · 25 containing glasses nickel, tin Science phosphoru legerade with the heat transfer surface of copper and in that for carrying out of the härdlödningen is conveyed:]]: värmebehandling at a temperature of at most 725 ° C. ·· · • · · · · •. ** ·. 2. Förfarande enligt patentkrav 1, kännetecknat av att härdlodslegeringens • · · 30 samplings and ligands inom omrädet 0.8-5.2 vic-% Ni, 0-27.4 vic-% • ♦. ·! *: Sn, 2, 2-10.9 wt-% P och resten koppar. • · ♦ • · 22. Värmeöverföringsyta enligt patentkrav 21, kännetecknad av att ett • · ·] ... φ coloringxlingsrör med porös inre eller yttre yta har genom svetsning • ♦ \ 'j. framställts av koppar- eller kopparlegeringsbandet. ···· • · ♦ • · • · 25 23. Värmeöverföringsyta enligt nägot av patentkraven 17-22,:. kännetecknad av att den porösa Värmeöverföringsytan har bildats i ··· ·. · * ·. face av anordningsgruppen omfattande heat sink, heat spreader, • · ·, heat pipe- och vapor chamber-anordningar, kokarytor för kylning av • I ». ***. electronic componenter, solpaneler, kylelement, bilkylare och andra • · 30 kylare säsom olika gjutkokiller och gjutkylare. • · • · • · · ·