WO2002000358A1

WO2002000358A1 - Layer deposition on superconductor particles by sputtering or evaporation

Info

Publication number: WO2002000358A1
Application number: PCT/US2001/041145
Authority: WO
Inventors: Matthew J. Holcomb
Original assignee: Nove Technologies Inc
Current assignee: Nove Technologies Inc
Priority date: 2000-06-27
Filing date: 2001-06-25
Publication date: 2002-01-03
Anticipated expiration: 2002-12-27
Also published as: AU2001273638A1

Abstract

A plurality of superconductor particles are formed being of a first material which is relatively brittle and is selected to be in a superconductive state at a relatively high temperature, typically above 77K which is the temperature of liquid nitrogen. A coating layer is formed on each superconductor particle, the coating layer being of a second material selected to be substantially non-reactive with the first material. The coated particles are then mixed with a third material to form a composite wherein the third material is in proximity to the first material but separated by the second material. The third material is selected to be relatively ductile when compared to the first material and to be driven to a superconductive state by the first material when the first material is in a superconductive state and the third material is in proximity to the first material. The second material protects the third material from oxidation by the first material. The second material is selected and is sufficiently thin to allow for the third material to be driven to the superconductive state by the first material through the second material. The invention relates to a method and apparatus for forming coating layers on the superconductor particles utilizing for example sputtering or evaporation.

Description

LAYER DEPOSITION ON SUPERCONDUCTOR PARTICLES BY SPUTTERING OR EVAPORATION

BACKGROUND OF THE INVENTION

This is a Continuation-In-Part of U.S. Patent Application No. 09/433,267

filed on November 4, 1999 which is a Continuation-In-Part of U.S. Patent No.

5,998,336 filed on February 26, 1997.

1). Field of the Invention

This invention relates to a method and apparatus for producing a

superconductor property composite.

2). Discussion of Related Art

U.S. Patent No. 5,998,336 describes principles relating to the manufacture

of a superconductor property composite utilizing the proximity effect. A plurality of superconductor particles are formed being of a first material which is

relatively brittle and is selected to be in a superconductive state at a relatively

high temperature, typically above 77K which is the temperature of liquid

nitrogen. A coating layer is formed on each superconductor particle, the coating layer being of a second material selected to be substantially non-reactive with the first material. The coated particles are then mixed with a third material to form a composite wherein the third material is in proximity to the first material but

separated by the second material. The third material is selected to be relatively

ductile when compared to the first material and to be driven to a

superconductive state by the first material when the first material is in a superconductive state and the third material is in proximity to the first material.

The second material protects the third material from oxidation by the first

material. The second material is selected and is sufficiently thin to allow for the

third material to be driven to the superconductive state by the first material

through the second material.

The need has"arisen to develop a method and apparatus for forming

coating layers on the superconductor particles.

SUMMARY OF THE INVENTION

According to one aspect of the invention a method for producing a

superconductor property composition is provided. A plurality of

superconductor particles are formed, the superconductor particles being of a first

material being relatively brittle and being selected to be in a superconductive state above 10K. Coating particles from a source of coating particles of a second

material are directed to the superconductor particles, thereby at least partially

coating a surface of each superconductor particle with an initial coating layer to

form a plurality of partially coated particles. Each partially coated particle is

then rotated relative to the source, resulting in rotated particles. Coating

particles from the source of coating particles are then directed towards the

rotated particles, thereby further coating the respective surface of each

superconductor particle with a further coating layer to form a plurality of further

coated particles.

The further coated particles may be located in proximity to a third

material to form the composition. The third material may be selected to be

relatively ductile when compared to the first material and to be driven to a

superconductive state by the first material when the first material is in a

superconductive state and the third material is in proximity to the first material. The second material is selected to be substantially non-reactive with the first

material and is sufficiently thin to allow for the third material to be driven to a superconductive state by the first material through the second material.

The invention also provides a method for producing a superconductive

property composition, comprising forming a plurality of superconductor

particles of a first material being relatively brittle and being selected to be in a

superconductive state above 10K, locating the superconductor particles in a

chamber, introducing gas particles into the chamber, creating a voltage on a sputter target, the sputter target being located in the chamber and being made of

a second material, the gas particles being ionized and then attracted to the

sputter target due to the voltage being created on the sputter target, the gas ions

colliding with the sputter target so that the coating particles of the second

material are released from the sputter target and directed from the sputter target

to the superconductor particles so that the surface of each superconductor

particle is coated with a layer to form a plurality of coated particles.

According to another aspect of the invention, a method for producing a

superconductor property composition is provided, comprising forming a

plurality of superconductor particles of a first material being relatively brittle

and being selected to be in a superconductive state above 10K, dropping the

superconductor particles from a higher elevation to a lower elevation through a

volume under a force of gravity, directing coating particles from a source of

coating particles of a second material to the superconductor particles while dropping through the volume, thereby coating a surface of each superconductor

particle with a coating layer to form a plurality of coated particles, and catching the superconductor particles at the lower elevation.

The invention also provides a method for producing a superconductor property aggregate comprising forming a plurality of superconductor particles

of a first material being relatively brittle and being selected to be in a

superconductive state above 10K, and simultaneously directing coating particles

of a second material onto each superconductor particle from a first direction and

from a second direction being at an angle relative to the first direction, thereby

simultaneously coating a surface of the superconductor particle in both the first

and second directions with a coating layer.

The invention also provides a method for producing a superconductive

property composition, comprising forming a plurality of superconductor

superconductive state above 10K, and applying a coating layer on a surface of

each superconductor particle to form a plurality of coated particles, the coating

layers being applied with the superconductor particles of a temperature of below

500°C.

The invention also provides apparatus for coating a plurality of

superconductor particles comprising a chamber, a container, a source of gas

particles, a sputter target, a voltage source, and a stirring device. The container

is located within the chamber with purposes of holding the superconductor

particles. The source of gas particles introduces gas particles into the chamber.

The sputter target is located in the chamber. The voltage source is coupled to the sputter target so as to create a voltage on the sputter target. The gas particles are ionized and then attracted to the sputter target due to the voltage and collide with the sputter target so that coating particles are released from the sputter

target. The coating particles have movement directed towards the

superconductor particles so that a coating layer is formed on a surface of at least

some of the superconductor particles. The stirring device is connected to the

particles so as to stir the superconductor particles in order to ensure coverage of

coating layers on more of the particles than without stirring.

The invention also provides apparatus for coating a plurality of

superconductor particles comprising a chamber, a higher container, a lower

container, and a source of coating particles. The higher container is for holding

and dropping the superconductor particles from a high elevation to a lower

elevation through a volume in the chamber under a force of gravity. The lower

container is located at the lower elevation to catch the superconductor particles

after dropping through the volume. The source of coating particles are of a

second material. The coating particles are directed from the source to the

superconductor particles while dropping through the volume, thereby coating a

surface of each superconductor particle with a coating layer to form a plurality of

coated particles. The invention also provides apparatus for coating a plurality of

superconductor particles comprising a chamber, a container, a heating element, a

voltage source, and a material within the chamber. A container is located within the chamber for holding the superconductor particles. The heating element is located within the chamber. The voltage source is coupled to the heating element so that the heating element heats up when the voltage source is

operated. The material is located within the chamber and is being heated by the

heating element, heating of the material causing evaporation thereof into coating

particles. The coating particles form a layer on the superconductor particles. The

material may be selected from the group consisting of silver and its alloys,

niobium and its alloys, a niobium titanium alloy, lead and its alloys, a lead

bismuth alloy, tin and its alloys, and indium and its alloys.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is further described by way of examples with reference to

the accompanying drawings wherein:

Figure 1 is a cross-sectional side view of apparatus for coating a plurality

of particles, according to one embodiment of the invention;

Figure 2 is a view of superconductor particles which are sputtered with an

initial coating layer utilizing the apparatus of Figure 1;

Figure 3 is a view similar to Figure 2 after the superconductor particles are

stirred;

Figure 4 is a view similar to Figure 3 after a further coating layer is

sputtered on the superconductor particles;

Figure 5 is a view similar to Figure 4 after further stirring and sputtering

onto the superconductor particles;

Figure 6 is a cross-sectional side view of a wire made out of a three

component composition including coated particles of Figure 5 which are mixed

with a ductile material;

Figure 7 is a cross-sectional side view of apparatus for coating a plurality

of particles, according to another embodiment of the invention; Figure 8 is a side view of one superconductor particle which is sputtered

with an initial coating layer utilizing the apparatus of Figure 7;

Figure 9 is a view similar to Figure 8 after the superconductor particle is rotated as it falls through a volume defined within the apparatus of Figure 7;

Figure 10 is a view similar to Figure 9 after a further coating layer is sputtered onto the superconductor particle;

Figure 11 is a view similar to Figure 10 after further rotation of and

deposition onto the superconductor particle, with recirculation as required;

Figure 12 is a cross-sectional side view of apparatus for coating a plurality of particles, according to a further embodiment of the invention;

Figure 13 is a cross-sectional side view of apparatus for coating a plurality

of particles, being a modification of the apparatus of Figure 12;

Figure 14 illustrates coated superconductor particles which are loosely

arranged without a material between them; and

Figure 15 illustrates the superconductor particles after they are

compressed into a two component composition.

DETAILED DESCRIPTION OF THE INVENTION

Figure 1 of the accompanying drawings illustrates apparatus 20 for

plating a plurality of superconductor particles, according to an embodiment of

the invention. The apparatus 20 includes a chamber 22, a container 24, a stirring

device 26, a sputter target 28, and a voltage source 30 within the chamber 22, and

a pump 32 and an argon gas supply 34 located outside the chamber 22.

The container 24 has a relatively wide base 36 near a base of the chamber

22, and sides 38 extending upwardly from the base 36. The stirring device 26

includes an actuator 40 and a link 42. The link 42 has one end connected to the

actuator 40. The actuator 40 may for example be an electric motor with an

eccentric shaft which vibrates the link 42. The link 42 is preferably vibrated in at

least first and second transverse directions, such as in a circle. Another end of

the link 42 is connected to the container 24. Any movement of the link 42 is

transferred to the container 24. The container 24 is therefore also moved or

vibrated in first and second transverse directions when the actuator 40 is

operated.

The sputter target 28 is located above the container 24 and a conductive

ring 44 is located below a periphery of the sputter target 28. The sputter target

28 is connected to a negative terminal of the voltage source 30 and the ring 44 is

connected to a positive terminal of the voltage source 30.

The pump 32 is connected via a line 46 to the chamber 22. Operation of the pump 32 causes a reduction in pressure within the chamber 22.

The argon gas source 34 is connected to the chamber 22 via a line 48

having a valve 50 located therein. The argon gas source 34 may for example be a

pressurized cylinder filled with argon gas. Opening or closing of the valve 50

may control flow of argon gas particles into the chamber 22.

In use, the container 24 is filled with a plurality of ceramic superconductor

particles 100. U.S. Patent No. 5,998,336, which is incorporated herein by

reference, describes how the particles 100 can be formed and the materials that

they are made of. Suffice to say that they are relatively brittle ceramic particles

and that they generally have superconductor critical temperatures (T_c) between

10K and 130K, including individual temperatures in between.

The pump 32 is operated so that the pressure within the chamber 22

reduces to about 10^'7 torr. The valve 50 is then opened and a small amount of

argon gas flows from the argon gas source 34 through the valve 50 into the

chamber 22 resulting in an increase in pressure to about 10^"3 torr. Argon gas

particles are ionized to Ar^* ions and then attracted to the sputter target 28

because of the negative voltage that is applied to the sputter target 28. The

voltage source 30 is then energized which turns the sputter target 28 into a

cathode and the ring 44 into an anode. In accordance with general principles

relating to sputter deposition, the argon ions collide with a lower surface of the

sputter target 28, resulting in release of coating particles 102 from the sputter

target 28. The coating particles 102 have high kinetic energy, but numerous collisions with gas particles in the chamber 22 both lower the energy of the coating particles and randomize the trajectories of the coating particles. The

velocity of the coating particles 102 is primarily directed downwardly towards

the superconductor particles 100.

Reference is now made to Figure 1 in combination with Figure 2 to Figure

5. Figure 2 illustrates the superconductor particles 100 during an initial coating by the coating particles 102. The coating particles 102 form an initial coating

layer 104 on each of upper ones of superconductor particles 100. The directions

of movement of many of the coating particles 102 change as they approach the

superconductor particles 100 between the sputter target 28 and the

superconductor particles 100, due to multiple collisions between respective ones

of the coating particles 102 and with argon gas particles the directions of

movement of the coating particles 102 are thus multidirectional before they

collide with the superconductor particles 100. This has the advantage that initial

coating layers 104 can be formed on surfaces that are not entirely horizontal. It is

therefore possible to form the initial coating layers 104 also on surfaces that are

vertical or substantially vertical to the same extent that they are formed on

horizontal surfaces. A larger area of one of the superconductor particles 100 is

thereby more uniformly coated than when the direction of movement of the

coating particles 102 are unidirectional.

The actuator 40 is continuously operated while the superconductor

particles are being sputtered. Figure 3 illustrates what happens to the superconductor particles 100, sputtered as shown in Figure 2, after being stirred due to operation of the actuator 40. Some of the superconductor particles 100A sputtered as shown in Figure 2, move down while other ones of the

superconductor particles 100B move up. Stirring also causes rotation of some or

all of the particles sputtered as shown in Figure 2 in directions 106 relative to the

position of the sputter target 28. As a result, previously unsputtered surfaces of the superconductor particles 100 are exposed to the top and therefore towards

the sputter target 28.

Figure 4 illustrates the arrangement of superconductor particles of Figure

3 after further sputtering. Although Figure 4 is shown separate from Figure 3, it

should be understood that the steps carried out in Figures 3 and 4 may occur

simultaneously. In Figure 4, the exposed upper surfaces of the superconductor

particles located at the top are sputtered as in Figure 2. More surfaces of more of

the superconductor particles 100 are thereby covered with further coating layers

108.

By repeating the process shown in Figure 3 and Figure 4, all or

substantially all surfaces of the superconductor particles 100 can be covered with

enveloping coating layers 110 as shown in Figure 5. The combination of the

superconductor particles 100 and the coating layers 110 are hereinafter referred

to as "coated particles 112".

As illustrated in Figure 6 and further described in U.S. Patent No.

5,998,336, the coated particles 112 are mixed with a material 114 and drawn into wire having a three component composition. The material 114 is chosen to be

relatively ductile when compared to the material of the superconductor particles 100. As such, the material 114 provides ductility to the wire. In general, the

material 114 becomes superconductive at temperatures much lower than the

relatively high temperatures that the superconductor particles 100 become

superconductive. Lead is an example of a material which can be used for the material 114. As described in U.S. Patent No. 5,998,336, the superconductor

particles 100 can drive the material 114 to a superconductive state if the material

114 is in close proximity to the superconductor particles 100. In addition, the

material of the coating layers 110 has to be sufficiently thin and be selected of a

material which allows for the material 114 to be driven to a superconductive

state by the superconductor particles 100. An example of the material of the

coating layers 110 (and therefore also of the sputtered target 28 in Figure 1) is

silver. The main purpose of the coating layers 110 is to protect the material 114

from oxidation by the superconductor particles 114 when in the composite

shown in Figure 6 and also to protect the superconductor particles 100 from

environmental oxidation before being mixed into the composite of Figure 6.

As mentioned, an advantage of the use of the apparatus of Figure 1 is that

the coating particles shown in Figure 2 deposit from different sides onto each

superconductor particle 100. Another advantage is that the superconductor

particles remain at a relatively low temperature during the coating process,

typically about 200°C. A temperature below 500°C of the superconductor particles 102 is particularly beneficial because of a substantially reduced likelihood that the material of the superconductor particles 100 will lose oxygen and thus their superconducting properties.

One disadvantage of the apparatus of Figure 1 is that the sputter target 28

has to be replaced from time to time. Furthermore, it may be difficult to mix the

superconductor particles 100 to an extent which ensures suitable and uniform

forming of coating layers 110 at a relatively high throughput rate. A further

disadvantage of the use of the apparatus 20 is that it does not lend itself to continuous commercial production because the container 24 continually has to be

removed from the chamber 22 in order to replace coated particles with uncoated superconductor particles.

Figure 7 illustrates an alternative apparatus 130 which may overcome

many of the disadvantages associated with the apparatus 20 of Figure 1. The

apparatus 130 includes a chamber 132, a pump 134, and an argon gas supply 136,

serving the same purposes and being operated the same as the chamber 22,

pump 32, and argon gas supply 34, respectively, of the apparatus 20 in Figure 1.

The apparatus 130 further includes an upper container 138, a lower container

140, a cylindrical sputter target 142, a voltage source 144, and a conductive pin

146. The upper container 148 is in the form of a funnel having a large upper

area 150 and a small lower mouth 152. The lower container 140 is also in the

form of a funnel having a large upper area 154 and a small lower mouth 156. The upper container 138 is located at a higher elevation and the lower container 140 is located at a lower elevation below the upper container 138. An imaginary

volume 160 is defined having a height extending from the upper area 154 of the

lower container 140 to the lower mouth 152 of the upper container 138, and a

width corresponding to a width of the upper area 154 of the lower container 140.

The cylindrical sputter target 142 extends vertically through the chamber 132. The conductive pin 146 is located centrally within the cylindrical sputter

target and extends vertically through the cylindrical sputter target 142. The

volume 160 is located between the pin 146 and one side of the cylindrical sputter

target 142. When viewed from above, the cylindrical sputter target 142 entirely

encircles and encloses the volume 160. The cylindrical sputter target 142 is thus

located on all sides of the volume 160 when viewed from above.

The cylindrical sputter target 142 is connected to a negative terminal of

the voltage source 142 and the pin 146 is connected to a positive terminal of the

voltage source 142. The voltage source 142 serves the same purpose as the

voltage source 30 of the apparatus 20 in Figure 1.

In use, argon ions collide with a surface of the cylindrical sputter target

142, causing release of coating particles from the cylindrical sputter target 142. A

transporting device 164 such as a conveyor transports superconductor particles

100 to the upper area 150 of the upper container 138. The superconductor

particles 100 move through the upper container 138 to the lower mouth 152

thereof and then drop from the mouth 152 through the volume 160. The superconductor particles 100 are collected by the upper area 154 of the lower container 140 which catches the superconductor particles 100 and can move

through the lower container 140 to the lower mouth 156 thereof, whereafter they

are again collected by the transporting device 164 and transported and delivered

to the upper container 138.

The coating particles released from the cylindrical sputter target 142 move

in generally a horizontal direction 166 into the volume 160 and attach to the

superconductor particles 100. Some of the coating particles may move through

the volume 160 without attaching to any of the superconductor particles 100 and attach to an opposing side of the cylindrical sputter target 142.

An advantage of the apparatus 130 is that it is suitable for large-scale

production. One reason why it is suitable for large-scale production is because it

can be scaled so that the volume 160 is sufficiently high to accommodate a

required number of superconductor particles. Another reason why it is suitable

for large-scale production purposes is because large amounts of superconductor

particles can be collected in the containers 138 and 140 and be fed through the

volume 160 as required.

A further reason why the apparatus 130 of Figure 7 has commercial

applicability is that there is no need to remove any containers from the chamber 132. Coated particles 170 can simply be extracted from the lower container 140

simply directing them to an opening out of the chamber 132. A valve mechanism

(not shown) may also be provided which ensures that a negative pressure within the chamber 132 is maintained when the coated particles 170 are removed. Once the coated particles 170 are removed, uncoated superconductor particles 172 may be introduced into the system and be fed to the upper container 138.

Figure 8 to Figure 11 now illustrate how one superconductor particle 100

is coated utilizing the apparatus 130 of Figure 7.

As shown in Figure 8, coating particles 102 have velocities in multiple

directions just before contacting the superconductor particle 100. The coating

particles 102 thus contact the superconductor particle 100 from multiple

directions which are at angles relative to one another. Faces of the

superconductor particle 100 which are at angles relative to one another are thus

covered with an initial coating layer 104. It should be noted that a left side of the

superconductor particle facing towards a closest wall of the cylindrical sputter

target 142 is covered more with an initial layer 104 than a right side of the

superconductor particle 100 facing away from the closest wall of the cylindrical

sputter target 142.

As shown in Figure 9, the superconductor particle 100 rotates in a

direction 106 falling through the volume 160. A number of factors may

contribute to rotation in a direction 106 of the superconductor particle 100 including collisions between the superconductor particle 100 and other

superconductor particles or with some of the coating particles 102, the location of

the center of gravity of the superconductor particle 100, especially once the initial

coating layer 104 is formed, or rotation induced by the upper container 138 onto the superconductor particle 100. The result of the rotation in the direction 106 is that a face 107 of the superconductor particle 100, which is not coated is step

shown in Figure 8, is exposed to a closest wall of the cylindrical sputter target 142.

Figure 10, illustrates a step that is typically carried out together with the

step illustrated in Figure 9. The superconductor particle 100 is further coated with a further coating 108 on the exposed surface 107. Further rotation and

coating of the superconductor particle 100 results in coating 110 which entirely

envelops the superconductor particle 100 as shown in Figure 11. Depending on

the dimensions of the components of the apparatus 130, in particular the volume

160, and other processing conditions, it may occur that the superconductor

particle 100 is not sufficiently enveloped by a coating layer 110. In such a case,

the partially coated superconductor particles are returned and recirculated

utilizing the transporting device 164. Figure 7 illustrates one example of a drop through sputtering apparatus

that may be used. Other devices may be alternatively used such as a cylindrical

magnetron sputtering gun. A cylindrical magnetron sputtering gun utilizes a

cylindrical sputter target such as the cylindrical sputter target 142 of Figure 7

which is connected to a negative terminal of a voltage source. An additional

cylinder is located around the cylindrical sputter target thereof which is

connected to a positive terminal of the voltage source. The additional cylinder

replaces the function of the pin 146 of Figure 7. Figure 12 illustrates a further apparatus 180 that can be used for coating superconductor particles. The apparatus 180 includes a chamber 182, a container

184, a stirring device 186, a heating element 188, and a voltage source 190 located

within the chamber 182, and a pump 192 located outside the chamber 182.

The container 184 and the stirring device 186 are the same and serve the

same function as the container 24 and stirring device 26 of the apparatus 20 in

Figure 1. Opposing ends of the coil 188 are connected to opposing terminals of

the voltage source 190 so that the coil 188 is heated when the voltage source 190

is operated. The coil 188 is coated with a layer of material 194. The pump 192 is connected to the chamber 182 via a connection line 196.

In use, the pump 192 is operated until the pressure within the chamber

182 reduces to about 10^'7 torr. The voltage source 190 is then operated so that the

coil 188 is heated. The material 194 is typically silver which evaporates at a

temperature of about 960°C. The coil 188 is heated to a temperature above

960°C, typically to about 1000°C which causes evaporation of the silver material

194. The evaporated silver form coating particles 102 which move with linear

trajectories away from the coil. A fraction of the coating particles move toward

the superconductor particle 100 located within the container 184.

The apparatus 180, as with the apparatus 20 of Figure 1, does not lend

itself to large-scale production. It may however be possible to incorporate an

evaporation system such as the coil 188 and the material 190 into an apparatus

such as the apparatus 130 of Figure 7, in which case the sputter target 142 may be removed. Sputtering however has certain advantages over evaporation. One

advantage of sputtering is that a coating layer can be formed on superconductor

particles at very low temperatures as previously described. Evaporation, by

contrast, generally results in a coating layer being formed on superconductor

particles at temperatures above 500°C, the temperature at which the superconductor particles 100 lose oxygen and thus their superconductor

properties which could cause unwanted reaction between coating particles and

the material of the superconductor particles. Another advantage of the use of

sputtering is that deposition is multidirectional as described with reference to

Figure 2 and Figure 8. Evaporation, by contrast, generally results in

unidirectional deposition of coating layers on superconductor particles.

The further problem with the apparatus 180 in Figure 12 is that the

coating particles 102 do not only find their way onto the superconductor

particles 100 but also find their way onto other components within the chamber

182 including any windows that are located on the chamber 182. Figure 13

illustrates apparatus 180A which is essentially a modification of the apparatus

180 of Figure 12. The apparatus 180 also includes a chamber 182A, a container

184A, a stirring device 186A, a voltage source 190A, a pump 192A, and a line

196A connecting the pump 192A to the chamber 182A. In addition, an enclosure

197 is located within the chamber 182A. The container 184A is located outside

the enclosure 197. Opposing terminals of the voltage source 190A are connected

to the enclosure 197. A conductive cup 198 is located within the enclosure 197. An outlet passage 199 is formed out of a lower surface of the enclosure 197. When the voltage source 190A is operated, current passes through the enclosure

197 and the cup 198. The current heats material 194A located within the cup 198,

causing evaporation thereof. The evaporated material then attaches to inner

surfaces of the enclosure 197. The current passing through the enclosure 197

heats the particles attached to the inner surface thereof, causing evaporation

thereof into coating particles which leave the enclosure 197 in a downward

direction. None of the coating particles move in sideways or upward directions.

Side and upper surfaces of the chamber 192A are not covered by any coating

particles. The coating particles attached to superconductor particles in the

container 184A.

The foregoing description relates primarily to the manufacture of a three

component composition as shown in Figure 6. The three component

composition includes superconductor particles 100, coating layers 110 on the

superconductor particles 100, and a material 114 between the coated

superconductor particles. In such a composition the superconductor particles

100 are generally relatively brittle and the material 114 is generally relatively

ductile. Such a composition finds particular application in a composition

wherein the superconductor particles 100 display superconductive characteristics

at relatively high temperatures. In such a composition, the coating layers 110 are

typically made of silver.

It should however be understood that the invention may also find application in the manufacture of a two component composition. Figure 3 illustrates a plurality of superconductor particles 200 which are coated with

coating layers 210. The coated particles 212 are loosely grouped together

without a third material between them. As shown in Figure 15, the coated

particles 212 are then compressed into a composition wherein the layers 210 form

interfaces between the superconductor particles 200. The coating layers 210 are

typically not made of silver since silver cannot be driven to a superconductive

state. Typical materials that can be driven to a superconductive state include

niobium and its alloys, a niobium titanium alloy, lead and its alloys, a lead

bismuth alloy, tin and its alloys, and indium and its alloys. These materials may

however be more reactive with the first material than silver. Silver is also more

permeable to oxygen allowing for replacement of oxygen into the first material if

necessary.

Any one of the sputter target 28 in figure 1, the cylindrical sputter target

142 in Figure 7, or the material 194 in Figure 12 or the material 194A in Figure 13

may be of these materials that can be driven to a superconductive state.

While certain exemplary embodiments have been described and shown in

the accompanying drawings, it is to be understood that such embodiments are

merely illustrative and not restrictive of the current invention, and that this

invention is not restricted to the specific constructions and arrangements shown

and described since modifications may occur to those ordinarily skilled in the art.

Claims

CLAIMSWhat is claimed:

1. A method for producing a superconductor property composite, comprising:

forming a plurality of superconductor particles of a first material being

relatively brittle and being selected to be in a superconductive state above 10K;

directing coating particles from a source of coating particles of a second

material to the superconductor particles, thereby at least partially coating a

surface of each superconductor particle with an initial coating layer to form a

plurality of partially coated particles;

rotating each partially coated particle relative to the source, resulting in

rotated particles; and

directing coating particles from the source to the rotated particles, thereby

further coating the respective surface of each superconductor particle with a

further coating layer to form a plurality further coated particles.

2. The method of claim 1, further comprising:

locating the further coated particles in proximity to a third material to

form the composite, the third material being selected to be relatively ductile

when compared to the first material and to be driven to a superconductive state

by the first material when the first material is in a superconductive state and the third material is in proximity to the first material, the second material being selected to be substantially nonreactive with the first material and being

sufficiently thin to allow for the third material to be driven to a superconductive

state by the first material through the second material.

3. The method of claim 1, further comprising:

locating the superconductor particles in a chamber;

introducing gas particles into the chamber;

creating a voltage on a sputter target, the source being the sputter target,

the sputter target being located in the chamber and being made of the second

material, the gas particles being ionized and then attracted to the sputter target

due to the voltage being created on the sputter target, the gas ions colliding with

the sputter target so that the coating particles of the second material are released

from the sputter target and directed from the sputter target to the

superconductor particles so that the surface of each superconductor particle is

coated with the at least one of the layers.

4. The method of claim 3, further comprising: dropping the superconductor particles from a higher elevation to a lower

elevation through a volume under a force of gravity, the coating particles being

directed from the sputter target to the superconductor particles while dropping

through the volume, thereby coating the surface of each superconductor particle with at least one of the layers; and catching the superconductor particles at the lower elevation.

5. The method of claim 4 wherein the sputter target includes at least one

component located on opposing sides of the volume.

6. The method of claim 5 wherein the sputter target forms an enclosure

around the volume.

7. The method of claim 1, further comprising:

dropping the superconductor particles at least a first time from a higher

elevation to a lower elevation through a volume under a force of gravity, the

coating particles being directed from the source to the superconductor particles

while dropping through the volume, thereby coating the surface of each

superconductor particles with the at least one of the layers; and

catching the superconductor particles at the lower elevation.

8. The method of claim 7, further comprising: transporting the superconductor particles back to the higher elevation;

and dropping the superconductor particles at least a second time from the

higher elevation to the lower elevation through the volume under a force of gravity.

9. The method of claim 1 wherein the second material is silver.

10. The method of claim 1 wherein at least one of the layers is formed by simultaneously directing the coating particles onto each superconductor particle

from a first direction and from a second direction being at an angle relative to the

first direction, thereby simultaneously coating the surface of the superconductor

particle with at least one of the layers in both the first and second directions.

11. The method of claim 1 wherein at least one of the layers is applied at a

temperature below 5~00°C

12. A method for producing a superconductor property composite,

comprising:

forming a plurality of superconductor particles of a first material being

locating the superconductor particles in a chamber;

introducing gas particles into the chamber; creating a voltage on a sputter target, the sputter target being located in

the chamber and being made of a second material, the gas particles being ionized

and then attracted to the sputter target due to the voltage being created on the sputter target, the gas ions colliding with the sputter target so that coating particles of the second material are released from the sputter target and directed

from the sputter target to the superconductor particles and coating a surface of

each superconductor particle with layer to form a plurality of coated particles.

13. The method of claim 12, further comprising:

locating the further coated particles in proximity to a third material to

form the composite, the third material being selected to be relatively ductile

when compared to the first material and to be driven to a superconductive state

by the first material when the first material is in a superconductive state and the

third material is in proximity to the first material, the second material being

selected to be substantially nonreactive with the first material and being

state by the first material through the second material.

14. A method for producing a superconductor property composite,

comprising: forming a plurality of superconductor particles of a first material being

dropping the superconductor particles from a higher elevation to a lower

elevation through a volume under a force of gravity;

directing coating particles from a source of coating particles of a second material to the superconductor particles while dropping through the volume, thereby coating a surface of each superconductor particle with a coating layer to

form a plurality of coated particles; and

catching the superconductor particles at the lower elevations.

15. The method of claim 14, further comprising:

locating the further coated particles in proximity to a third material to

form the composite, the third material being selected to be relatively ductile

when compared to the first material and to be driven to a superconductive state

third material is in proximity to the first material, the second material being

selected to be substantially nonreactive with the first material and being

state by the first material through the second material.

16. A method for producing a superconductor property composite,

relatively brittle and being selected to be in a superconductive state above 10K; simultaneously directing coating particles of a second material onto each

superconductor particle from a first direction and from a second direction being

at an angle relative to the first direction, thereby simultaneously coating a surface of the superconductor particle in both the first and second directions with a coating layer.

17. The method of claim 16, further comprising:

locating the further coated particles in proximity to a third material to

form the composite, the third material being selected to be relatively ductile

when compared to the first material and to be driven to a superconductive state

by the first material when the first material is in a superconductive state and the third material is in proximity to the first material, the second material being

selected to be substantially nonreactive with the first material and being

state by the first material through the second material.

18. A method for producing a superconductor property composite,

comprising:

forming a plurality of superconductor particles of a first material being

relatively brittle and being selected to be in a superconductive state above 10K; applying a coating layer on a surface of each superconductor particle to

form a plurality of coated particles, the coating layer being applied with the

superconductor particles at a temperature below 500°C.

19. The method of claim 18, further comprising: locating the further coated particles in proximity to a third material to form the composite, the third material being selected to be relatively ductile

when compared to the first material and to be driven to a superconductive state

third material is in proximity to the first material, the second material being

selected to be substantially nonreactive with the first material and being

state by the first material through the second material.

20. Apparatus for coating a plurality of superconductor particles, comprising:

a chamber;

a container for holding the superconductor particles within the chamber;

a source of gas particles that introduces gas particles in the chamber;

a sputter target located within the chamber;

a voltage source coupled to the sputter target so as to create a voltage on

the sputter target, the gas particles being ionized and then attracted to the

sputter target due to the voltage and colliding with the sputter target so that

coating particles are released from the sputter target, the coating particles having

movement directed towards the superconductor particles so that a coating layer

is formed on a surface of at least some of the superconductor particles; and a stirring device connected to the particles so as to stir the superconductor

particles in order to ensure coverage of coating layers on more of the particles than without stirring.

21. The apparatus of claim 20 wherein the stirring device is connected to the container and vibrates the container.

22. The apparatus of claim 21 wherein the container moves in at least first and

second transverse directions.

23. The apparatus of claim 20 wherein the target is made of a material

selected to be substantially nonreactive with a material of the superconductor

particles if the material of the particles is in a superconductive state above 10K.

24. The apparatus of claim 23 wherein the material of the target is silver.

25. Apparatus for coating a plurality of superconductor particles, comprising:

a chamber;

a higher container for holding and dropping the superconductor particles

from a higher elevation to a lower elevation through a volume in the chamber

under a force of gravity; a lower container located at the lower elevation to catch the

superconductor particles after dropping through the volume;

a source of coating particles of a second material, the coating particles being directed from the source to the superconductor particles while dropping through the volume, thereby coating a surface of each superconductor particle with a coating layer to form a plurality of coated particles.

26. The apparatus of claim 25 further comprising:

a transporting device that collects the particles form the lower container

and transports and delivers the particles to the higher container.

27. The apparatus of claim 25 further comprising:

a source of gas particles that introduces gas particles into the container,

the source of coating particles being a sputter target within the chamber; and

a voltage source coupled to the sputter target so as to create a voltage on

the sputter target, the gas particles being ionized and then attracted to the

sputter target due to the voltage and colliding with the sputter target so that

movement directed towards the particles so that a coating layer is formed a

surface of at least some of the particles.

28. The apparatus of claim 27 wherein the sputter target includes at least one

component located on opposing sides of the volume.

29. The apparatus of claim 28 wherein the sputter target forms an enclosure around the volume.

30. The apparatus of claim 29 wherein the sputter target substantially entirely encloses the volume when viewed from above.

31. Apparatus for coating a plurality of superconductor particles, comprising: a chamber;

a container, for holding the superconductor particles, within the chamber;

a heating element located within the chamber;

a voltage source coupled to the heating element so that the heating

element heats up when the voltage source is operated;

a material within the chamber, the material being heated by the heating

element, heating of the material causing evaporation thereof into coating

particles, the coating particles forming a layer on the superconductor particles,

wherein the material is selected from the group consisting of silver and its

alloys, niobium and it is alloys, a niobium titanium alloy, lead and its allows, a

lead bismuth alloy, tin and its alloys, and indium and its alloys.

32. The apparatus of claim 31 wherein the material is a layer on the heating

element.

33. Apparatus for coating a plurality of superconductor particles comprising: a chamber; a container, for holding the superconductor particles, within the chamber;

an enclosure within the chamber, the container being located outside the

enclosure, the enclosure having a material located therein, and an outlet passage;

and

a heating device located in a position to heat the material in the enclosure

so as to cause evaporation of the material into coating particles, the coating particles leaving the enclosure through the outlet passage and then forming a layer on the superconductor particles.

34. The apparatus for claim 33 wherein the heating device is the enclosure,

further comprising: a voltage source coupled to the enclosure so as to pass current through the

enclosure causing heating of the enclosure, the enclosure heating the material.