EP0474724A1 - Improvements in materials - Google Patents

Abstract

Palladium materials, modified to change the local environment of deuterium under cold melting conditions, are effective in supporting cold melting when loaded with deuterium. Particular modifications are in the form of alloys or dispersions of Pd with Ce, Ag, LaNi5 and Ti, others relate to the particle size. Excess heat, tritium and neutrons were observed.

Description

IMPROVEMENTS IN MATERIALS

This invention concerns improvements in materials. More especially, it concerns improved materials for the heat-generating process now known as "cold fusion" or "solid state fusion".

There has been widespread interest in the "cold fusion" process since Professors Fleischmann and Pons described the unusual experimental effects obtained by the electrolysis of heavy water (D„0) using a palladium cathode. (J. Electroanal. Chem., 261, (1989) 301-308.) Whilst the effects are still being investigated to try to prove or disprove the fusion theory, no completely plausible alternative explanation has yet been put forward. Hereinafter, the process producing the heat generating effect will be generally described as a process of the "cold fusion" type, and is intended to include variations from the process described by Fleischmann and Pons. In particular, we wish to include processes which "charge" a hydrogen/deuterium storage material by methods other than the electrochemical methods described by Fleischmann and Pons. There is a need for cathode materials which exhibit enhanced heat generating effects, for scientific study and for development of the process into a reliable and commercially utilisable power source. It should be understood that although this specification concentrates on the heat generating effect, the invention may find utility with respect to the other products of fusion, and hence may be used for the formation of tritium and/or the generation of neutrons.

We now provide a composition of matter in which cold fusion takes place when the composition is loaded with deuterium, comprising palladium modified to change the local environment for deuterium under cold fusion conditions.

In one embodiment, the invention may also be considered to arise from a palladium having a high and substantially stable dislocation density, or point defect concentration. In another embodiment, the invention may be considered to arise from the incorporation into the palladium material of centres for stress during the cold fusion process, whether at point defects or at boundary regions at which stress is created. A further embodiment incorporates a material having a high muon capture cross-section. A yet further embodiment utilises a coating on the palladium material. Another embodiment utilises palladium modified by the incorporation of lithium, especially enriched with Li .

It is one object of the invention to obtain a modified palladium having a high dislocation density or point defect concentration by virtue of its processing or the addition of alloying or other elements or substances which substantially affect the concentration and location of point defects. There are a variety of ways according to the invention that this desired object may be attained, which will be more fully described hereinafter.

A first group of methods for forming the modified palladium include mechanical methods, for example to cold work the metal, or to rapidly cool molten metal, for example by melt spinning, suitably by cooling at rates of the order of 10 to 10 C sec , or by rapidly cycling the metal through α and β phases, according to methods generally known in the art. The invention includes materials processed in such a way, generally known in the metallurgical art, to retain the α phase in the metal at high deuterium to metal ratios. The introduction of point defects by these methods is, however, sometimes not adequate since the defects may anneal out at temperatures as low as room temperature.

Moreover, some experimental results indicate that it may be desirable to modify the grain size and shape by annealing, for example after a drawing operation to bring the material to a desired diameter. Since the "cold fusion" process has generally been described as operating above room temperature, and substantial heat generation will cause local heating of the palladium anode, it is envisaged that point defects in the pure metal will relatively quickly be lost. It may therefore be preferred to use a second group of methods as described below, or to use a combination of methods from the first and from the second group.

The second group of methods according to the invention may be generally described as those producing controlled grain and sub-grain sizes. In its simplest form, controlled grain size- may be achieved by controlled recrystallisation according to generally known principles in the metallurgical art, whereby the grain surface areas and number of triple points may be adjusted. It is one theory that point defects and possibly activity in the "cold fusion" process may be concentrated at the grain boundaries. A particular embodiment of the invention utilises processing conditions to yield material having a fine grain structure in which the grains have an aspect ratio, considered as the ratio of length to diameter, of less than 10, and preferably approximately unity. We have experimental evidence to suggest that a controlled microstrueture, in which substantially uniform grain size in the range from 10 to 40 microns is preferred, offers improved performance in at least the heat generating process. These microstructures may be achieved by the competent metallurgist by methods generally known in the art, which will vary according to the prior metallurgical history of the palladium material, especially the extent of work hardening, and its current microstructure. For example, annealing a material with a grain size of less than 10 microns, and in which the aspect ratio of the grains is in excess of 10, to produce the desired grain sizes, is a method which is indicated to yield "active" palladium samples which exhibit the excess heat effect. Suitable annealing conditions, for a drawn material, are heating for approximately one hour at a temperature of approximately 650 C, desirably under vacuum or possibly under an inert gas. These temperature and time conditions may be varied, since there are a number of time-temperature curves depending upon the degree of work hardening, and providing that the desired microstructure is achieved.

Another method to be considered within this second group is the incorporation within the palladium of an additive which by itself contributes to the formation of point defects or contributes to their stability at elevated temperature. The term "additive" is to be given a wide meaning as including materials, whether elements or compounds, which under normal usage would be considered to be impurities; in such a case, and providing the impurity has a beneficial overall effect, or at least no overall adverse effect, the impurity may be retained in the palladium, rather than being refined out. It may be desirable to reduce, rather than eliminate the amount of any such impurity. The use as additives as herein understood of elements such as gold, calcium, copper, iron and platinum, as well as boron, carbon, sulphur, silicon and lithium, and rare earth metals including particularly cerium, is therefore to be considered, especially as we expect the additive elements to concentrate at the grain boundaries, and thus have a considerable influence on the chemical and/or nuclear reactions taking place. A further additive to be considered is uranium, especially U235.

A particular embodiment of the use of an additive is the formation of amorphous palladium materials, which may be achieved by the incorporation of an additive such as silicon. PdSi and PdSiCr alloys can be produced quite readily in amorphous form, and although these devitrify at about 400 C, they are thought to be adequately stable up to these temperatures. It is considered that improved hydrogen/deuterium diffusion/solubility may be improved by utilising controlled devitrification to produce extremely short range order crystallinity. Elements which are worthy of consideration for forming eutectics or near eutectics with palladium for the formation of amorphous materials include silicon, boron, carbon, lithium, potassium, sodium and iron.

A further embodiment of the use of an additive is the formation of dispersed oxide particles, for example zirconia, dispersed intermetallic compounds, for example LaNi_c or FeTi, or dispersed hydride forming metals, within a palladium matrix. To avoid disadvantageous physical or other properties of such materials, it may be suitable to microencapsulate the additive, for example by depositing Pd on the additive by standard electroless or electro plating techniques, followed by pressure sinter consolidation and cold deformation, or a sintering process may be used. Other materials indicated for trial in the cold fusion process are powder metallurgy compacts, eg encased within a palladium skin, and Pd/AloO-, for example where the amount of Al„0- is approximately 2 to 5% by wt, or Pd/Ti where titanium particles are dispersed in a Pd/Ti solid solution or are in a palladium matrix but are surrounded by a Pd/Ti solid solution. Such materials are believed to exhibit significant internal stress caused by differential expansion caused by volume changes on the formation of deuterides and related compounds, or solutions of deuterium, upon "charging" of the palladium material with deuterium during or prior to the cold fusion process. The quantity of any additive is preferably less than about 20 at%, more preferably less than about 10 at%, and most preferably less than about 5 at%. In general, the concentration of point defects may be monitored by the resistivity of the material, as well as by crystallography and surface spectroscopic techniques.

An embodiment of the present invention utilises the high stress and high point defect concentration arising from deposited coatings. The coating may be solely palladium, or a palladium/additive mixture, and may be deposited upon a matrix by electroplating, electroless plating, sputtering, chemical vapour deposition, thick film techniques, electroforming (for example, varying the electroforming temperature can be utilised to tailor the stress and coating properties) or other method yielding the desired result.

Although the materials of the invention are indicated for the electrolytically induced cold fusion process as described by Fleischmann and Pons, we also wish to include a process by which the material has deuterium concentrated within the lattice, perhaps by formation of deuteride(s), by pressure effects. Theoretical physics indicates that adequate pressure for fusion cannot be achieved by conventional methods, but the cold fusion process appears to run counter to present theory in a number of ways. It will be desirable to provide the highest possible pressure of deuterium, and we envisage that methods may involve sonic waves, in the manner of experiments studying microgravity. Other methods of generating very high pressures include the use of diamond anvils, and a method involving the use of magnetically induced pressure by localised domain wall movements by fluctuating magnetic fields; in the latter method, it would be desirable to incorporate in the material of the invention one or more elements to increase the susceptibility of the material to magnetic effects, for example a small ^■ amount, such as less than 1% by weight, of cobalt. We also wish to include variations of these methods incorporating cooling of the material under sustained or fluctuating high pressure, to temperatures below 0 C, for example to -70 C. Other methods of inducing cold fusion may be developed; the present invention does not rely solely upon electrolytic methods.

As mentioned above, in one embodiment the palladium may incorporate lithium. Preferably, the amount of lithium is less than about 20 at %, more preferably less than about 10 at %, most preferably less than about 5 at %, in any macroscopic region of material.

In a particular embodiment of the invention, the lithium used is enriched with the isotope Li . The normal proportion of Li in lithium is 7.4% by wt, and it is envisaged that Li contributes to the possible lithium-deuterium reaction. A suitable enrichment would give a Li content of above 10% by weight of the lithium present, and this may usefully exceed 20% by weight. Lithium may be incorporated into palladium by a number of different processes, including alloying, although the vast difference in melting point between lithium (mp~180°C) and palladium (mp~1700°C) means that at the melting point of palladium the lithium has a very significant vapour pressure and is easily lost by evaporation. The lithium may be introduced into the palladium electrochemically, by using a palladium cathode in a lithium salt solution, or using a non-aqueous system, including, for example a molten salt system. As another possible method, there should be mentioned thermal diffusion of lithium atoms from a deposited surface layer of lithium, the layer having been deposited by plating, or any alternative deposition method. Diffusion methods are known to the skilled man in relation to other metals. A powder route starting with LiH and Pd sponge, eg under a H/D atmosphere, may also be used.

It will be appreciated that a preparative method involving diffusion of lithium into bulk palladium, whether electrochemically or thermal, will tend to produce a concentration gradient, the absolute values of concentration and the steepness of the gradient depending upon the method and the conditions used. A concentration gradient may be desirable in that there will be localised stress and palladium lattice point defects in the surface region, and this may influence the hydrogen/deuterium solubility and mobility, and in turn affect the heat generating effect. We do not wish to be bound by any expressions of theory, since the fusion process is not yet well understood.

The palladium/lithium materials of the invention may additionally comprise other metals or materials which do not adversely affect the overall performance or properties for the intended use, or which improve the performance or general properties of the material. Another embodiment of the invention provides a palladium materia comprising palladium and an additive having a high captur cross-section for muons. In general, the muon captur cross-section increases with increasing atomic number. Preferabl the additive is an element selected from the rare earths, yttriu and scandium, and gadolinium or cerium are particularly indicated. The Actinides are also to be considered, as well as some heavie elements such as uranium.

The additive may be a single additive or a combination of two o more of such additives, and may be present in admixture with othe substances which do not have an adverse effect on the hea generating process.

Suitable amounts of the additive are less than 15 at %, preferabl less than 8 at %, especially about 1 at %, based on the palladium. We believe that a balance should be attained between the amount o additive present, which affects the material's ability to capture muon, and the adverse effect the additive has upon deuteriu solubility in the palladium.

The invention also extends to an improved cold fusion proces comprising carrying out or initiating the process at a temperatur below ambient, preferably below 10°C, more preferably below 0°C and most preferably below -10°C, for example at a temperature o the order of -40 C to -70 C. Accordingly, it is preferred t operate the process with efficient heat removal, for example b excess heat removal by a flow of liquid through the anode material and optionally with external cooling. It will be appreciated that, particularly if an aqueous electrolyte is being used, the freezing point of the electrolyte must be below the operating temperature, and this may be achieved by the addition of a salt or an organic "anti-freeze" substance, for example methanol or ethylene glycol.

The invention also includes increasing the deuterium concentration by utilising a material not previously proposed, and which has the desired combination of hydrogen/deuterium solubility and diffusion characteristics. The material may be selected from the rare earths, for example especially cerium, yttrium, scandium, the Actinides, uranium, tantalum, niobium, vanadium, intermetallics and mischmetals having the desired properties, and palladium/silver alloys. The materials may incorporate dispersed hydrogen storage elements or compounds, of which Pd/Ag and LaNi,- may particularly be mentioned.

Particularly, in the case of uranium and the Actinides, it is contemplated that radioactivity, by producing high energy emissions, may assist to initiate any fusion reaction, and therefore the invention contemplates the use of materials enriched with radioactive isotopes. Care has, of course, to be taken according to recognised procedures for handling radioactive substances.

Certain of the new materials are not ideally suited for use as electrodes in aqueous systems, for example because of the formation of passivating surface layers or competing reactions and gas formation or loss of physical properties in the presence hydrogen/deuteruim; and the invention includes surface coating t material with palladium or a palladium/silver alloy. Such surfa coating may be effected in a number of ways, including electrole and electro plating, thin film depositions such as sputtering chemical vapour deposition, etc.

The invention further includes the new materials dispersed conventional metallurgical techniques in a stable matrix, of whi palladium and palladium/silver alloys are favoured.

Although the use of titanium has been proposed for use in the "co fusion" process, the present invention provides titanium dispers in, or surface coated with, palladium or palladium/silver, which believed to offer particular advantages for use in aqueo electrolyte systems.

In another aspect, the inventions provides a palladium having modified surface. The modified surface serves one or more of t following purposes: to increase hydrogen/deuterium adsorption; to control hydrogen/deuterium desorption; to control undesired surface reactions; to control surface area; to control surface qualitly, including controlling surface impuri levels; and to provide desired dimensional stability. It will be appreciated that if the hydrogen adsorption is increased while at the same time the hydrogen desorption is decreased, the overall effect is to increase the amount of hydrogen (and its isotopes) containable within the material, and to increase the opportunity for fusion or other heat generating processes.

In particular, the invention provides a material comprising a surface coating or modified surface region. The material matrix may be palladium or a palladium alloy or solid solution.

In addition to a surface coating, which may be applied by a method selected according to the desired coating and matrix compositions, from electroless or electro plating, thin or thick film depositions including sputtering, chemical vapour deposition and othe appropriate coating processes, the invention includes the incoporation of desired elements or compounds in a surface region, thereby to create a concentration gradient of element or compound, in the electrode material. This may be achieved by diffusion int the matrix from a coating, generally using thermally induce diffusion, and methods for creating a modified surface region ar known to the skilled man in relation to other materials. W consider that such a modified surface region, having concentration gradient, will be considerably stressed and will hav a high concentration of lattice point defects, which we believe t significantly contribute to the adsorption of hydrogen and it isotopes and their diffusibility within the material, and to th heat generating processes within the material. Suitable coatings according to the invention include in particular palladium and palladium/silver alloys. It may be desirable to surface coat a palladium matrix with palladium, for example to coat with palladium black. Other surface coatings or surface regions may contain amorphous materials. A surface coating will also generally have a high stress and high concentration of point defects, and these may be advantageous in the "cold fusion" or heat generating process as discussed above, although we do not wish to be bound by any theory expressed herein.

The invention encompasses the use of the modified palladium materials as described above in a "cold fusion" type process. The invention further provides a heat generating electrochemical process of the "cold fusion" type, comprising concentrating deuterium in a material according to the invention, for example by electrolysing D-0 utilising a cathode which is a modified palladium material as described above. The invention additionally provides an electrolysis cell for use in a heat generating electrochemical process of the "cold fusion" type, comprising an anode, and a cathode which is a modified palladium material as described above. In illustration of the present invention, palladium containing small amounts of additives was prepared, was melted and cast, Before being drawn twice to form an electrode rod of 8mm diameter. One sample of the electrode was annealed under vacuum for one hour at 650 C. Studies of the microstructure of the annealed rod compared to the unannealed rod showed that the unannealed rod had grain size of less than 10 microns maximum dimension, with a aspect ratio for the grains of greater than 10, whereas th annealed rod had recrystallised to a grain size of from 10 to 40 microns and with an aspect ratio of less than 10. The rods were then used in a "cold fusion" electrolysis cell under conditions as reported in the literature. The unannealed rod did not show any heat-generating activity despite a considerable period of charging, whereas the annealed rod exhibited the excess heat effect, with bursts of heat. The palladium contained 0.002 % boron, 0.001 % copper, 0.001 % iron, 0.001 % platinum, 0.003 % gold and 0.003 % calcium, in addition to low amounts of aluminium, magnesium, nickel, silicon and silver.

In a further example, 25% Ag - 75% Pd alloy was used as the cathode in the electrolysis of heavy water, using both LiOD and NaOD in solution in D„0 as electrolyte. Current densities in the range

2 2 from 200mA/cm to 750mA/cm were used. Products detected included were tritium and neutrons, initiating that fusion was taking place.

We carried out studies using Temperature Programmed Reduction and electrochemical studies, and were able to conclude that, for reasons still unexplained, the palladium hydride formed using Li OH in light water was stabilised in comparison with the hydride using Na OH or K0H in light water.

Claims

WE CLAIM

1. A composition of matter in which cold fusion takes place when the composition is loaded with deuterium, comprising palladium modified to change the local environment for deuterium under cold fusion conditions.

2. A composition according to claim 1, wherein the palladium is combined with a material having a high muon capture cross-section.

3. A composition according to claim 2, wherein the combination material is selected from the rare earths including yttrium and scandium.

4. A composition according to claim 3, wherein the combination material is one or more of gadolinium and cerium.

5. A composition according to claim 1, wherein the palladium has a high and stable dislocation density.

6. A composition according to claim 5, wherein the palladium has deposited thereon a coating.

7. A composition according to claim 6, wherein the coating acts to increase the stress on palladium grains and/or to increase the point defect concentration.

A composition according to claim 6, wherein the coating comprises a modified surface region on the palladium which is effective to increase deuterium absorption and/or to control deuterium desorption.

A composition according to claim 8, wherein the modified surface region comprises palladium black or a palladium-silver alloy.

10. A composition according to claim 1, comprising palladium having dispersed therein or alloyed therewith, one or more of the components cerium, yttrium, scandium, an Actinide, tantalum, niobium, vanadium, silver, LaNi- and titanium.

11. A composition according to one of claims 1 to 10, wherein the palladium has a grain size in the range 10 to 40 microns.

12. A composition according to claim 11, wherein the aspect ratio of the grains is approximately unity.

13. A composition according to claim 1 or 6, wherein the palladium is modified by the incorporation of lithium.

14. A composition according to claim 13, wherein the lithium is enriched with Li .

15. A process for producing one or more of heat, neutrons and tritium by the cold fusion of deuterium loaded in palladium, wherein the palladium is a composition according to any one of the preceding claims.

16. A process according to claim 15, carried out or initiated at a temperature below ambient.

17. A process according to claim 16, carried out or initiated of a temperature below 10 C.

18. A process according to any one of claims 15, 16 and 17, carried out by electrolysis in a lithium electrolyte, in which the lithium is enriched in Li .

19. A cold fusion electrochemical cell, comprising a cathode which is a modified palladium according to any one of claims 1 to 14.