# US 7,743,502 B2 · Chemically compatible, lightweight heat pipe

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- Number: US 7,743,502 B2
- Document ID: US7743502B2
- Status: Granted
- Kind: B2
- Application number: 11/363,806
- Filed: 2006-02-28
- Published: 2006-07-06
- Granted: 2010-06-29
- Earliest claimed: 2001-01-03
- Assignees: Thermal Corp.
- Inventors: John H. Rosenfeld; G. Yale Eastman
- Web page: https://patentgrep.com/patent/US7743502B2

## CPC

- F28D 15/0233: {the conduits having a particular shape, e.g. non-circular cross-section, annular (F28D15/0241, F28D15/0266 take precedence)}
- C23C 30/00: Coating with metallic material characterised only by the composition of the metallic material, i.e. not characterised by the coating process (C23C26/00, C23C28/00 take precedence)
- F28D 15/02: in which the medium condenses and evaporates, e.g. heat pipes {(heat pipes used in solar heat collectors F24S10/95; in radiators F28D1/0226; in nuclear reactors G21C15/257)}
- F28F 19/02: by using coatings, e.g. vitreous or enamel coatings
- F28F 19/06: of metal
- F28F 21/081: {Heat exchange elements made from metals or metal alloys}
- G06F 1/203: {for portable computers, e.g. for laptops}
- H10W 40/73: for cooling by change of state
- Y10S 138/07: Resins
- Y10S 165/905: Materials of manufacture
- Y10T 29/4935: Heat exchanger or boiler making
- Y10T 29/49353: Heat pipe device making
- Y10T 29/49359: Cooling apparatus making, e.g., air conditioner, refrigerator
- Y10T 29/49377: Tube with heat transfer means
- F28D: HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT (fluid heaters having heat generating means and heat transferring means F24H; furnaces F27; details of heat-exchange apparatus of 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 (making metal-coated products by extrusion B21C23/22; covering with metal by connecting pre-existing layers to articles, see the relevant places, e.g. B21D39/00, B23K; metallising of glass C03C; metallising mortars, concrete, artificial stone, ceramics or natural stone C04B41/00; enamelling of, or applying a vitreous layer to, metals C23D; treating metal surfaces or coating of metals by electrolysis or electrophoresis C25D; single-crystal film growth C30B; by metallising textiles D06M11/83; decorating textiles by locally metallising D06Q1/04)
- F28F: DETAILS OF HEAT-EXCHANGE AND HEAT-TRANSFER APPARATUS, OF GENERAL APPLICATION (water and air traps, air venting F16)
- G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N)
- H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10
- Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

The present invention provides an apparatus including a magnesium alloy vessel that is substantially free of aluminum and zinc, but including magnesium in combination with a gettering metal and a method for making such apparatus. The magnesium alloy vessel has a hollow interior cavity containing a working fluid, with a stable, protective layer formed on the inside wall of the vessel so as to establish non-corrosive compatibility with the working fluid.

## Claims

### Claim 1

A method for manufacturing a heat transfer device comprising the steps of:
(A) alloying a magnesium base metal that is substantially free of aluminum and zinc to a getter metal so as to form a magnesium getter alloy;
(B) fabricating said magnesium getter alloy into a vessel having an interior wall defining a hollow interior cavity;
(C) forming a stable protective layer upon said interior wall, wherein said stable protective layer is in thermally-compatible contact with said interior wall;
(D) filling at least a portion of said hollow interior cavity with a capillary wick structure;
(E) evacuating said hollow interior cavity; and
(F) charging a portion of said hollow interior cavity with a working fluid, wherein said working fluid is in chemically non-reactive contact with said stable protective layer.

### Claim 2 (depends on 1)

The method according to claim 1 wherein said getter metal is selected from the group consisting of zirconium, titanium, hafnium and yttrium.

### Claim 3 (depends on 1)

The method according to claim 1 wherein zirconium is alloyed to said magnesium base metal in a weight percentage of about 0.1-5.0%.

### Claim 4 (depends on 1)

The method according to claim 1 wherein zirconium is alloyed to said magnesium base metal in a weight percentage of about 0.6%.

### Claim 5 (depends on 1)

The method according to claim 1 wherein a nitride derivative of said magnesium getter alloy is formed on said interior wall of said vessel as the stable protective layer.

### Claim 6 (depends on 5)

The method according to claim 5 wherein ammonia is charged into said hollow interior cavity as said working fluid.

### Claim 7 (depends on 1)

The method according to claim 1 wherein an oxide derivative of said magnesium getter alloy is formed on said interior wall of said vessel as the stable protective layer.

### Claim 8 (depends on 7)

The method according to claim 7 wherein water is charged into said hollow interior cavity as said working fluid.

### Claim 9

A method for preventing base metal corrosion in a heat transfer device, comprising the steps of:
(A) alloying a magnesium metal that is substantially free of aluminum and zinc to a getter metal so as to form a magnesium getter alloy wherein said magnesium getter alloy functions as a base metal for said heat transfer device;
(B) fabricating said base metal into a vessel having an interior wall defining a hollow interior cavity;
(C) filling at least a portion of said hollow interior cavity with a capillary wick structure;
(D) evacuating said hollow interior cavity;
(E) charging a portion of said hollow interior cavity with a working fluid; and,
(F) oxidizing said interior wall of said vessel so as to form a stable protective layer, wherein said stable protective layer comprises an oxidation product of said base metal and said working fluid, and further wherein said protective layer inhibits contact between said interior wall and said working fluid so as to prevent corrosive interaction by said working fluid upon said interior wall.

### Claim 10 (depends on 9)

The method according to claim 9 wherein said getter metal is selected from the group consisting of zirconium, titanium, hafnium and yttrium.

### Claim 11 (depends on 9)

The method according to claim 9 wherein zirconium is alloyed to said magnesium metal in a weight percentage of about 0.1-5.0%.

### Claim 12 (depends on 9)

The method according to claim 9 wherein zirconium is alloyed to said magnesium metal in a weight percentage of about 0.6%.

### Claim 13 (depends on 9)

The method according to claim 9 wherein ammonia is charged into said hollow interior cavity as said working fluid.

### Claim 14 (depends on 9)

The method according to claim 9 wherein water is charged into said hollow interior cavity as said working fluid.

### Claim 15

A method for preventing hydrogen gas generation in a heat transfer device, comprising the steps of:
(A) alloying a magnesium metal, substantially free of aluminum and zinc, to a getter metal so as to form a magnesium getter alloy;
(B) fabricating said magnesium getter alloy into a vessel having an interior wall defining a hollow interior cavity;
(C) forming a stable protective layer upon said interior wall, wherein said stable protective layer comprises substantially a combination of an oxide of said getter metal and an oxide of said magnesium metal, and further wherein said getter metal oxide reacts to absorb hydrogen gas produced within said hollow interior cavity;
(D) filling at least a portion of said hollow interior cavity with a capillary wick structure;
(E) evacuating said hollow interior cavity; and
(F) charging a portion of said hollow interior cavity with a working fluid, said working fluid being liquid water.

### Claim 16 (depends on 15)

The method according to claim 15 wherein said getter metal is selected from the group consisting of zirconium, titanium, hafnium and yttrium.

### Claim 17 (depends on 15)

The method according to claim 15 wherein zirconium is alloyed to said magnesium metal in a weight percentage of about 0.1-5.0%.

### Claim 18 (depends on 15)

The method according to claim 15 wherein zirconium is alloyed to said magnesium metal in a weight percentage of about 0.6%.