Classifications

• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C1/00—Making non-ferrous alloys
  • C22C1/04—Making non-ferrous alloys by powder metallurgy
  • C22C1/0466—Alloys based on noble metals
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F7/00—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression
  • B22F7/06—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools
  • B22F7/08—Manufacture of composite layers, workpieces, or articles, comprising metallic powder, by sintering the powder, with or without compacting wherein at least one part is obtained by sintering or compression of composite workpieces or articles from parts, e.g. to form tipped tools with one or more parts not made from powder
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B15/00—Layered products comprising a layer of metal
  • B32B15/01—Layered products comprising a layer of metal all layers being exclusively metallic
  • B32B15/018—Layered products comprising a layer of metal all layers being exclusively metallic one layer being formed of a noble metal or a noble metal alloy
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C5/00—Alloys based on noble metals
  • C22C5/04—Alloys based on a platinum group metal
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/12—Both compacting and sintering
  • B22F3/14—Both compacting and sintering simultaneously
  • B22F2003/145—Both compacting and sintering simultaneously by warm compacting, below debindering temperature
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
  • B22F3/24—After-treatment of workpieces or articles
  • B22F2003/247—Removing material: carving, cleaning, grinding, hobbing, honing, lapping, polishing, milling, shaving, skiving, turning the surface
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
  • B22F2998/10—Processes characterised by the sequence of their steps
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy

Definitions

• the invention relates to composite sputtering target assemblies made by hot pressing metal or metal containing powders into a metal backing plate. More particularly, the invention relates to a method of making a hot pressed composite sputtering target assembly that reduces the amount of relatively expensive materials such as precious metal containing materials required to prepare the target by confining these materials to the area of the target utilized in the sputtering process. The invention further relates to the target, which is produced by the method.
• a typical sputtering system includes a means for generating a high energy plasma that removes the material to be deposited from the surface of a source forming a vapor of that material that condenses on the surface of the desired substrate.
• the source of the material to be deposited on the substrate is called a sputtering target.
• a sputtering target can be composed solely of the material to be deposited or in some cases the material to be deposited is formed into an object called a sputtering target tile that is joined to a dissimilar material called the sputtering target backing plate and the entire assembly is called the sputtering target.
• the choice of sputter target construction depends on the sputtering system used, the physical and electrical properties of the material to be deposited, and the expense of the material to be deposited.
• the high energy plasma continuously erodes the surface of the sputtering target material forming a depression known as an "erosion groove" in the surface of the sputtering target.
• This erosion groove is commonly referred to in the thin film industry as the “racetrack” due to its unique shape.
• the erosion groove becomes deep enough that further sputtering of the target material is impractical and at that point the sputtering target is considered “spent”.
• a method to reduce the amount of precious metal containing materials used in the precious metal containing sputtering target manufacturing process is to confine the precious metal containing material to the actual area where it is consumed; the sputtering erosion groove. It is conceivable to reduce the amount of precious metal containing material used to manufacture a target by greater than 40% by restricting the precious metal containing material to the erosion groove area of the sputtering target.
• a way to achieve this goal is to manufacture a composite sputtering target whereby the precious metal containing material is formed into a shape similar to the shape of the sputtering erosion groove and applied to a backing plate composed of a relatively inexpensive material specially machined to accommodate the shape of the erosion groove of the sputtering process.
• the present invention does not require that a spent target go through a refining process, it results in a significant reduction in the inventory of precious metal used for sputtering (and especially in a reduction of the material that is tied up in spent targets which are not serving in production capacity, but instead is undergoing the recycling process.).
• the process involves HIP'ing powder contained within a metal can, it is relatively costly due to the use of expensive canning materials, machining, canning as well as HIP procedures and equipment which add to manufacturing cost.
• the expensive target material is not confined to the sputtering area of the target, thus the amount of the expensive target material used to form this type of sputtering target is not significantly reduced.
• Sandlin et al. disclose a method to refurbish spent sputtering targets in U. S. Pat. No. 7,175,802 whereby new sputtering material is applied to a spent sputtering target by filling the sputtering erosion groove with the new material. This process is also accomplished using HIP'ing.
• the invention does not confine the expensive sputtering material to the sputtering area of the target, but does reuse the spent target instead of recycling it.
• there still remains a considerable amount of expensive material in use that is not used in the sputtering process leading to a still relatively high cost of ownership.
• the disclosed process requires the spent targets to be thoroughly immersed in the powder of the expensive material that requires removal and recycling after pressing.
• the present invention provides an efficient and relatively low cost method of producing composite sputtering target assemblies whereby the precious metal containing sputtering material is confined to the sputtering area of the target assembly. This is achieved by applying the precious metal containing sputtering material to a backing plate assembly of a substantially lower cost material that has a cavity machined into its surface that approximates the sputtering erosion groove of spent targets. Additionally, the process can be applied such that the erosion groove of a spent target is filled using the process of the present invention. In this instance, the spent target becomes the backing plate, and does not require additional machining to form a form for the newly added precious material.
• the composite target of the present invention is fabricated using vacuum hot pressing that utilizes re-usable graphite dies instead of single- use metal cans and the amount of precious metal containing material powder used in the forming process is greatly reduced.
• the result is a composite sputtering target that requires at least 50% less of the expensive material than a target produced purely of the precious metal containing material.
• the process significantly reduces amount of precious metal that needs to be dedicated to a sputtering process since it eliminates side lining of the spent target material into the recycling portion of the production cycle of precious material used in sputtering targets. This advantage results in a tremendous and unforeseen increase in the efficiency of the precious material dedicated to the sputtering process.
• a method of making a sputtering target assembly that confines precious metal containing sputtering target materials to the sputtering area of the target thereby reducing the amount of precious metal containing sputtering material required to produce the sputtering target assembly, and further increases the efficiency of the material dedicated to the sputtering process, and thus reduces the cost of ownership of the sputtering target assembly as well as the capital investment needed for the sputtering process.
• the method involves providing a backing plate of a relatively inexpensive material, that is chemically and mechanically compatible with the precious metal containing sputtering material, with a depression in the surface, (which can in the first instance be machined into the backing plate) that corresponds to the sputtering erosion pattern observed in used sputtering targets, placing the backing plate into a graphite die shaped to accommodate the geometry (i.e., the size and shape) of the backing plate, filling the depression in the backing plate with a powder of the precious metal containing sputtering material, then placing a graphite ram on top of the powder layer.
• the die containing the backing plate powder assemblage is then placed in a vacuum hot press to consolidate and densify the precious metal containing sputtering target material powder into the backing plate depression.
• a vacuum hot press consolidate and densify the precious metal containing sputtering target material
• the hot pressing also facilitates the formation of a strong inter-metallic bond between the precious metal containing sputtering material and the backing plate material creating a strong mechanical attachment as well as an intimate electrical and thermal conduction path between the precious metal containing sputtering target material and the backing plate.
• a minimal amount of machining may be required to obtain the required dimensional specifications for the particular sputtering target design.
• a method of making a precious metal containing sputtering target assembly comprises 1) providing backing plate including a surface having a depression; 2) placing the backing plate into the cavity of a graphite die set prepared to accommodate the geometry backing plate; 3) forming a die assemblage by placing a sputtering material into the cavity in contact with the depression so as to completely cover the surface of the backing plate to a predetermined depth; 4) placing a graphite ram into the cavity of the assemblage so as to contact the top of the sputtering material; 5) placing the ram and die assemblage into the chamber of a vacuum hot press furnace and pressing them in vacuum at a sufficient pressure and a sufficient temperature for a sufficient period of time in order to densify and consolidate the sputtering material into the depression in the backing plate so as to form a sputtering target perform, and subsequently reducing the pressure on the ram to zero, cooling or allowing the hot press furnace chamber to cool to ambient temperature, and
• the backing plate is comprised of a material which differs from the sputtering target material and is comprised of one or more of molybdenum, niobium, tantalum or other refractory metals or alloys.
• the depression at least corresponds to the sputtering erosion pattern of a used sputtering target. More preferably, the depression corresponds to the erosion pattern of a spent target (i.e.
• the sputtering material is a powder comprising precious metal or a mixture of precious metal powders, or a mixture of precious metal powders and non- precious metal powders, or a mixture of precious metal powders, non precious metal powders, and metal oxide powders.
• the graphite die is of a geometry determined for the particular sputtering target assembly design being produced.
• Suitable sputtering material include powders of pure Ru, Rh, Pd, Re, Os, Ir, Pt or mixtures of Ru, Rh, Pd, Re, Os, Ir, Pt or mixtures of Ru, Rh, Pd, Re, Os, Ir, Pt, with transition metals such as Co, Cr, Ni, Fe, or mixtures of Ru, Rh, Pd, Re, Os, Ir, Pt, with transition metals such as Co, Cr, Ni, Fe, and oxides such as Ti ⁇ 2 or mixtures of Ru, Rh, Pd, Re, Os, Ir, Pt with oxides such as TiO 2 .
• a pure Ru powder is as used sputtering material and pure Mo is used for the backing plate.
• the backing plate is composed of pure Nb metal.
• the backing plate is composed of pure Ta.
• the present invention results in a savings of at least 25%, preferably at least 35% and most preferably at least 40% or more of the sputtering material needed for a sputtering target assembly as compared to the prior art solid sputtering target.
• a precious metal containing sputtering target of a rectangular geometry can be prepared using this invention with only 50% of the precious metal material requirement of a precious metal containing sputtering target prepared using only the precious metal containing material.
• FIG. 1 represents a cross-sectional view of a used precious metal containing sputtering target with a rectangular or circular geometry
• FIG. 2 represents a top view of a used precious metal containing sputtering target with a rectangular geometry
• FIG. 3 represents a top view of a used precious metal containing sputtering target with a circular geometry
• FIG. 4 represents a cross-sectional view of a backing plate containing a depression that corresponds to the sputtering erosion pattern for targets with either a rectangular or circular geometry;
• FIG. 5 represents a cross-sectional view of a first embodiment of this invention for a precious metal containing sputtering target with either a rectangular or a circular geometry;
• FIG. 6 represents a hot pressing die assemblage prior to hot pressing for consolidating sputtering material into a depression in the surface of a backing plate.
• FIG. 7 represents the hot pressing die assemblage of Figure 6 after hot pressing.
• the present invention relates to a method of making a composite sputtering target which is comprised of a backing plate and a sputtering zone which has been incorporated into a depression in the backing plate so as to provide a sputtering target assembly with sputtering material substantially only where is will be used in the sputtering process.
• the backing plate is a used target of the same material that is added as the sputtering material.
• the used target has a top surface with a depression that has been eroded during the sputtering process.
• the backing plate is a different material, such as a less expensive material that will bond with the sputtering material and provide chemical, thermal and electrical properties that are suitable to allow the composite target to be substituted for a target made exclusively from the sputtering material.
• the backing plate included in Figures 1-3 illustrate the appearance of a spent precious metal containing sputtering target of rectangular or circular geometry.
• Figure 1 describes the cross-section of a spent or used precious metal containing sputtering target 10, showing the depth and shape of the sputtering erosion groove 12.
• the erosion groove, 12, represented in Figure 1 is consistent with erosion grooves found in precious metal containing sputtering targets that have either a rectangular or circular geometry.
• Figure 2 shows the top view of a spent precious metal sputtering target 20 of rectangular geometry, showing the shape of the sputtering erosion groove 22.
• Figure 3 shows the top view of a precious metal containing sputtering target of circular geometry, 30, showing the shape of the sputtering erosion groove 32.
• An examination of these drawings shows that a considerable amount of precious metal sputtering material is left in the used target with as little as 25% of the material actually used in the sputtering process.
• the present invention reduces the amount of precious metal containing material in a sputtering target by confining the precious metal containing material to the areas consumed in the sputtering process.
• This invention achieves this by using a backing plate, which in one embodiment is composed of a relatively inexpensive material, such as Mo, Ta, Nb, or other refractory metals and alloys, that is mechanically and chemically compatible with the precious metal containing material.
• Figure 4 illustrates a cross sectional view of a backing plate 40, that has a top surface 41 with a depression 42 or in this case, a groove.
• the depression can be the wear path or erosion groove of a used target in the event that the backing plate comprises a used or spent target.
• the depression 42 can be a groove machined into the top surface, 41 of the backing plate.
• the groove which corresponds to or approximates the geometry of the sputtering erosion groove, is illustrated in Figure 1.
• the geometry of the erosion groove is used to determine the configuration of the depression.
• this information is used to maximize the configuration of the depression to balance the amount of sputtering target so that as small a volume of sputtering material as possible can be used while allowing the target to be configured to maximize the production life of the target.
• Figure 5 illustrates the cross section of a composite sputtering target 50 where the precious metal containing sputtering material 51 forms a sputtering zone 52 which is mostly confined to the sputtering area of the composite sputtering target and most of the volume of the precious metal containing sputtering targets is composed of backing plate material 53.
• a savings of more than 50% in the amount of precious metal containing material required to produce a precious metal containing sputtering target can be achieved by this invention.
• FIGs 6 and 7 An example of how to produce this invention is illustrated in Figures 6 and 7.
• the refractory metal or alloy backing plate 60 having a surface including a machined groove 62 is placed inside a graphite hot press die 64 with the grooved surface up.
• a specified amount of sputtering material 66 is poured into the die on top of the backing plate 60 and the assemblage 65 is vibrated for a specified amount of time to evenly settle the powder onto the surfaces of the backing plate.
• a graphite hot press die ram 67 is placed into the die cavity until it contacts the surface of the sputtering material.
• the assemblage 65 is then placed in a hydraulic press and pressurized to a preset pressure for a specific amount of time to compact the powder onto the surfaces of the backing plate. After compaction, the assemblage is placed inside the furnace chamber of a vacuum hot press (not shown in the drawing). The ram of a hydraulic press that passes through the furnace chamber is lowered until it makes contact with the top of the hot press die ram. The furnace chamber is then sealed and is evacuated to between 50 to 200 mTorr. The assemblage is heated in the furnace chamber to a temperature between 800° and 1000 0 C and at that point pressure is applied to the hot press die ram via the hydraulic press ram in contact with it. The initial pressure applied is between 5 and 20 tons.
• ram pressure is slowly increased to a pressure between 10 and 200 tons; the ultimate ram pressure depending upon the size and geometry of the precious metal containing sputtering target being manufactured.
• the assemblage 65 is held at temperature and ram pressure for between 15 and 240 minutes; preferably between 20 and 60 minutes. After this time has elapsed, both the ram pressure and temperature are decreased until the assemblage 65 reaches ambient temperature and pressure and the vacuum level is raised to ambient pressure once the furnace has cooled to ambient temperature.
• Figure 7 illustrates the cross section of the assemblage 70 illustrated in Figure 6 after hot pressing has been completed.
• the sputtering material has been consolidated into the machined groove of the backing plate 73 to form a sputtering zone 74 which has a density of greater than 95% of the theoretical density of the sputtering material.
• the precious metal containing sputtering target pre-form composed of the consolidated sputtering material and backing plate 73 is removed from the hot press die 75, after the removal of the graphite die ram 77.
• the pre-form is then machined to final dimensions using CNC milling, diamond grinding, or electrical discharge machining (EDM).
• EDM electrical discharge machining
• the internal surfaces of the graphite die and the bottom of the graphite die ram can be lined with Mo or an other refractory metal foil to prevent the diffusion of carbon from the graphite die parts into the precious metal containing material.
• Another advantage in using this invention is that when the sputtering target is spent, the spent target can be used to produce a new sputtering target using the process described above where the spent target is substituted for the refractory metal or alloy backing plate containing the machined groove in the process. By doing so the amount of precious metal containing sputtering material used in the process is further reduced and the cost of the refractory metal or alloy backing plate containing the machined groove is eliminated. The process of reusing the spent composite sputtering target can be repeated numerous times.
• Yet another advantage in using this invention to produce precious metal containing sputtering targets is realized when the oxygen content of the precious metal containing material must be kept extremely low.
• oxygen is removed from the precious metal containing material due to its exposure to the graphite die under vacuum which provides an extremely reducing atmospheric condition within the graphite die even when the die surface are lined with Mo or other refractory metals.
• This reducing condition is capable of reducing the oxygen content of the precious metal containing material to below specified levels even when the oxygen content of the starting precious metal containing material exceeds said specification.
• This feature which is not encountered on other processes such as hot isostatic pressing (HIP'ing) where the precious metal containing material is isolated from reducing conditions by containment in a sealed metal can, provides for the use of precious metal containing materials with a wide range of starting oxygen contents leading to great flexibility in precious metal material sourcing, thus reducing costs.
• HIP'ing hot isostatic pressing
• a 2.03" diameter by 0.31" thick circular Ru composite sputtering target was fabricated with a Mo backing plate using the disclosed invention.
• a 2.03" diameter by 0.25" thick piece of Mo was machined in such a way as to provide a cavity concentric with the diameter of the Mo piece with a depth of 0.115" deep and top diameter of 1.84" and a bottom diameter of 1.55" (forming a frustum shape).
• the machined Mo piece was placed into a graphite hot press die and 100 grams of Ru powder was poured into the die cavity so as to fill the cavity in the Mo piece and cover the top of it.
• a graphite die ram was then placed into the die cavity and lowered onto the top of the Ru powder.
• the die assemblage was subsequently placed in a hydraulic press and pressed to a few hundred pounds of load to pre-compress the Ru powder. Then the die assemblage was placed into a vacuum hot press and processed at 1525°C for 0.5 hours at 500 psi at a vacuum level of 200 mTorr. After hot pressing the Ru/Mo composite piece was removed from the hot press and the surfaces machined to facilitate visual inspection.
• a visual inspection of the part indicated that the Ru and Mo bonded together during the hot pressing process without reacting significantly with one another indicating chemical compatibility. Furthermore, no cracks in either material were noted, indicating mechanical compatibility.
• the composite part was then placed in an EDM machine and sectioned so as to inspect the cross section of the composite. Visual and microscopic inspection reveal that no significant reaction occurred and no cracking or gaps were present in the composite further indicating chemical and mechanical compatibility between the two materials.
• the amount of Ru used to make this composite sputtering target was 100 grams which is less than 50% of the amount required, 202 grams, to make a pure Ru sputtering target of the same geometry.
• a 2.03" diameter by 0.31" thick circular Ru composite sputtering target was fabricated with an Nb backing plate using the disclosed invention.
• a 2.03" diameter by 0.25" thick piece of Nb was machined in such a way as to provide a cavity concentric with the diameter of the Nb piece with a depth of 0.115" deep and top diameter of 1.84" and a bottom diameter of 1.55" (forming a frustum shape).
• the machined Nb piece was placed into a graphite hot press die and 100 grams of Ru powder was poured into the die cavity so as to fill the cavity in the Mo piece and cover the top of it.
• a graphite die ram was then placed into the die cavity and lowered onto the top of the Ru powder.
• the die assemblage was subsequently placed in a hydraulic press and pressed to a few hundred pounds of load to pre-compress the Ru powder. Then the die assemblage was placed into a vacuum hot press and processed at 1525 0 C for 0.5 hours at 500 psi at a vacuum level of 200 mTorr. After hot pressing the Ru/Nb composite piece was removed from the hot press and the surfaces machined to facilitate visual inspection.
• a visual inspection of the part indicated that the Ru and Nb bonded together during the hot pressing process with out reacting significantly with one another indicating chemical compatibility. Furthermore, no cracks in either material were noted, indicating mechanical compatibility. The composite part was then placed in an EDM machine and sectioned so as to inspect the cross section of the composite. Visual and microscopic inspection reveal that no significant reaction occurred and no cracking or gaps were present in the composite further indicating chemical and mechanical compatibility between the two materials. [0039] The amount of Ru used to make this composite sputtering target was 100 grams which is less than 50% of the amount required, 202 grams, to make a pure Ru sputtering target of the same geometry.
• a 2.03" diameter by 0.31" thick circular Ru composite sputtering target was fabricated with a Ta backing plate using the disclosed invention.
• a 2.03" diameter by 0.25" thick piece of Ta was machined in such a way as to provide a cavity concentric with the diameter of the Ta piece with a depth of 0.115" deep and top diameter of 1.84" and a bottom diameter of 1.55" (forming a frustum shape).
• the machined Ta piece was placed into a graphite hot press die and 100 grams of Ru powder was poured into the die cavity so as to fill the cavity in the Ta piece and cover the top of it.
• a graphite die ram was then placed into the die cavity and lowered onto the top of the Ru powder.
• the die assemblage was subsequently placed in a hydraulic press and pressed to a few hundred pounds of load to pre-compress the Ru powder. Then the die assemblage was placed into a vacuum hot press and processed at 1525°C for 0.5 hours at 500 psi at a vacuum level of 200 mTorr. After hot pressing the Ru/Ta composite piece was removed from the hot press and the surfaces machined to facilitate visual inspection.
• a visual inspection of the part indicated that the Ru and Ta bonded together during the hot pressing process with out reacting significantly with one another indicating chemical compatibility. Furthermore, no cracks in either material were noted, indicating mechanical compatibility. The composite part was then placed in an EDM machine and sectioned so as to inspect the cross section of the composite. Visual and microscopic inspection reveal that no significant reaction occurred and no cracking or gaps were present in the composite further indicating chemical and mechanical compatibility between the two materials. [0043] The amount of Ru used to make this composite sputtering target was 100 grams which is less than 50% of the amount required, 202 grams, to make a pure Ru sputtering target of the same geometry.
• a 2.03" diameter by 0.31" thick circular Ru composite sputtering target was fabricated with a Ti backing plate using the disclosed invention.
• a 2.03" diameter by 0.25" thick piece of Ti was machined in such a way as to provide a cavity concentric with the diameter of the Ti piece with a depth of 0.115" deep and top diameter of 1.84" and a bottom diameter of 1.55" (forming a frustum shape).
• the machined Ti piece was placed into a graphite hot press die and 100 grams of Ru powder was poured into the die cavity so as to fill the cavity in the Ti piece and cover the top of it.
• a graphite die ram was then placed into the die cavity and lowered onto the top of the Ru powder.
• the die assemblage was subsequently placed in a hydraulic press and pressed to a few hundred pounds of load to pre-compress the Ru powder. Then the die assemblage was placed into a vacuum hot press and processed at 1525°C for 0.5 hours at 500 psi at a vacuum level of 200 mTorr. After hot pressing the Ru/Ti composite piece was removed from the hot press and the surfaces machined to facilitate visual inspection.
• a visual inspection of the part indicated that the Ru and Ti bonded together during the hot pressing process however there was evidence of reaction between the two materials with slight erosion of the Ti along the edges of the piece indicating possible chemical incompatibility. No cracks in either material were noted, indicating possible mechanical compatibility.
• the composite part was then placed in an EDM machine and sectioned so as to inspect the cross section of the composite. Visual and microscopic inspection revealed that significant reaction occurred between the two materials leaving a gap between the Ru and the Ti pieces further indicating chemical incompatibility between the two materials under the conditions used to process the composite.
• barrier material such as Mo, Nb, Ta, or other material that is chemically and mechanically compatible with both Ru and Ti could be inserted between the Ti backing plate and Ru powder load.
• the barrier material could be in the form of a foil, powder layer or coating applied with such methods as sputtering, flame spraying, or plasma spraying or other coating techniques.
• a ruthenium/niobium composite part was prepared that was 7.07" long by 2.30” wide by 0.5" thick by pressing ruthenium powder into a Nb backing plate 7.07" long by 2.30" wide by 0.400" thick containing a groove that was 1.77" wide at the top and 1.05" wide at the bottom and 0.233" deep running along the length of the backing plate.
• the plate was placed in a graphite die and filled with 715 grams of ruthenium powder which filled the groove and covered the backing plate.
• a die ram was place into the graphite die so that it would make contact with the ruthenium powder and the die pre-pressed before insertion into a vacuum hot press which was larger than the vacuum hot press used in the first four examples.
• the die In the vacuum hot press the die was heated to 1600 0 C and 26 tons of pressure was applied to the die ram. The die and contents were held under these conditions for four hours before cooling to room temperature. A higher density was achieved for this example and the following example than in the first four examples by holding the parts at temperature for a longer period of time.
• An evaluation of the ruthenium in the groove of the composite part indicated that the relative density of the ruthenium was 99% of the theoretical density of ruthenium which is 12.41 g/cc. Then an approximation of an erosion groove was machined into the surface of the ruthenium portion of the composite along the length to a maximum depth of 0.200".
• the composite was placed back into the graphite die and filled with 400 grams of ruthenium powder, which filled the groove and covered the composite part.
• a die ram was place into the graphite die so that it would make contact with the ruthenium powder and the die pre-pressed before insertion into a vacuum hot press. In the vacuum hot press the die was heated to 160O 0 C and 26 tons of pressure was applied to the die ram. The die and contents were held under these conditions for four hours before cooling to room temperature.
• An evaluation of the ruthenium pressed into the simulated erosion groove of the composite part indicated that the relative density of the ruthenium was 99% of the theoretical density of, which is 12.41 g/cc.

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• 2009
  • 2009-01-29 EP EP09723334A patent/EP2268434A1/de not_active Withdrawn
  • 2009-01-29 JP JP2011500765A patent/JP2011517730A/ja not_active Withdrawn
  • 2009-01-29 WO PCT/US2009/000646 patent/WO2009117043A1/en active Application Filing
  • 2009-02-13 TW TW098104770A patent/TW200940216A/zh unknown

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