CA1095212A - Process of producing a sintered compact - Google Patents
Process of producing a sintered compactInfo
- Publication number
- CA1095212A CA1095212A CA270,596A CA270596A CA1095212A CA 1095212 A CA1095212 A CA 1095212A CA 270596 A CA270596 A CA 270596A CA 1095212 A CA1095212 A CA 1095212A
- Authority
- CA
- Canada
- Prior art keywords
- cup
- solder
- sintered compact
- producing
- lid
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- 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
- B22F3/1208—Containers or coating used therefor
- B22F3/1258—Container manufacturing
-
- 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
- B22F3/1208—Containers or coating used therefor
- B22F3/1216—Container composition
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
- C04B35/10—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on aluminium oxide
- C04B35/111—Fine ceramics
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
- C04B35/64—Burning or sintering processes
- C04B35/645—Pressure sintering
Abstract
ABSTRACT OF THE DISCLOSURE
A process of producing a sintered compact comprises filling a cup with a powdered material to be sintered, putting on an opening of the cup a covering member consisting of a lid and solder so as to permit ventilation between the interior and exterior of the cup to form a cup assembly, applying heat as well as vacuum to the cup assembly to degas the powdered material, melting the solder by the continuation of heating to air-tightly seal the cup with the lid to obtain a closed cup compressible under high pressure at high temperature while maintaining the air-tight seal, and hot-pressing the closed cup to obtain a sintered compact.
The covering member may include a porous lid closing the cup and a solder put on the porous lid.
A process of producing a sintered compact comprises filling a cup with a powdered material to be sintered, putting on an opening of the cup a covering member consisting of a lid and solder so as to permit ventilation between the interior and exterior of the cup to form a cup assembly, applying heat as well as vacuum to the cup assembly to degas the powdered material, melting the solder by the continuation of heating to air-tightly seal the cup with the lid to obtain a closed cup compressible under high pressure at high temperature while maintaining the air-tight seal, and hot-pressing the closed cup to obtain a sintered compact.
The covering member may include a porous lid closing the cup and a solder put on the porous lid.
Description
1 The present invention relates -to a process o~ producing a sintered com-pact at high temperature under high pressure.
When hotpresslng a powde,red material to produce a sintered compact by means of hot isostatic prass or known super-pressure and high temperature apparatus for making a diamond, it provides little problem if the particle size of the material is coarser than several hundred microns, bu-t if' it is liner than several -ten microns~ particu.larly finer than one micron, it ;s impossible to obtain a densel-,y ~, concentrated structure if' the gas components are not completely removed ~rom the powdered material since numerous pores are contained in the obtained compact.
The above gas components include physically adsorbed gas, chemically adsorbed gas and those existing in th& fo,rm of oxides or hydroxides at the recesses or surf'aces of the particles. Therefore, however high vacuum is applied to ;~
the powdered material at room temperature, such gas components generate gases to cause pores in the compact by the heat , during hot-pressing~
For example, a vacuum is applied to ~C-Co powder mix at room temperature, and thereafter the temperature i9 raised to abou-t l000 C, there îs generated a great deal of gases such as H20, C02, C0 and H2.
The following is a consideration on the influence of
When hotpresslng a powde,red material to produce a sintered compact by means of hot isostatic prass or known super-pressure and high temperature apparatus for making a diamond, it provides little problem if the particle size of the material is coarser than several hundred microns, bu-t if' it is liner than several -ten microns~ particu.larly finer than one micron, it ;s impossible to obtain a densel-,y ~, concentrated structure if' the gas components are not completely removed ~rom the powdered material since numerous pores are contained in the obtained compact.
The above gas components include physically adsorbed gas, chemically adsorbed gas and those existing in th& fo,rm of oxides or hydroxides at the recesses or surf'aces of the particles. Therefore, however high vacuum is applied to ;~
the powdered material at room temperature, such gas components generate gases to cause pores in the compact by the heat , during hot-pressing~
For example, a vacuum is applied to ~C-Co powder mix at room temperature, and thereafter the temperature i9 raised to abou-t l000 C, there îs generated a great deal of gases such as H20, C02, C0 and H2.
The following is a consideration on the influence of
2 amount contained in WC-Co powder mix, the amoun-t 'being generally said to be about 0.3 to 0.6 ,~
The specific gravit~ of WC 10 ~ Co alloy is 14.6.
Therefore, the weight of 1 cc thereof is 14.6 g. Assuming ,~
that the po-wder mix has an amount of -5 ~ ~ 2;
11~.6 x 0.005 x 1/32 x 22.4 x 103 = 51,1(cc) The powder mix is then hot-pressed by means of hot isostatic ~s~
1 press under a pressu:re of 2000 atm at a temperature of 1400 C, and this amoun-t o:~ 51.1 cc becomes;
51.1 x 1/2000 x 1673/29~(room temperatu:re) = o. 14 tcc ~s a result, WC-10 ~ Co compac-t must contain 1~ ~ o~ pore.
Therefore 9 it is a'bsolutel-y impossible to o'btain a compact havi.ng a density of 100 '~
In the case of super-pressure and high temperature apparatus for making a diamond, the material to be sin-tered is enclosed in a solid pressure medium such as pyrophyllite, and since a tremendous pressure such as 500 to 600 ~g/mm2 is applied to -the pressure medium, the escape o~ gases is almost impossib].e, simi]arly ln an air-tight container.
There~ore, when sintering diamond or cubic(i.e. isometric) boron nitride, which is becoming a recent issue, there ari.ses the same problem as WC-Co powder mix men-tioned above.
Upon sintering alumina powder, also the same problem occurs When the powder material is subjected to gas analysis, there is o~-ten genera-ted a gas as much as 1 ~.
According to the present inventi.on, there is proposed a process o~ producin.g a sin-tered compact comprisirlg filling a cup with a powdered material to be sin-tered, putting on an opening o:~ the cup a coveri.ng member includin~ a lid and solder so as to permit ventilation between the interior and e~terior o.~ the cup to ~orm a cup assemblyg applying heat as well as vacuu~ to the cup assembly to degas the powdered material~ melting the solder by the co~tinuation o:~ heatlng to air-tightl-y seal the cup with the lidg and hot-pressing the cup to obtain a sintered compact.
~ccordingly, it is an object of the present invention to provide a process o.~' producing a sintered compact making it possible to obtain a densely concentrated structure by ,.~ . -. . ", , .. : .. .
52~
1 co~lpletely degassing a powdered materia] so a~ to eliminate pores caused b-,y gases.
It is another ob,jec-t of the present invention to provide an effective process ~or ob-taining with certaint~
a dense compact by air-tightly sea:Ling a cup containing a powdered material during degassing without using any speci~ic device.
Other objects and ~eatures Or the present invention - will be apparent from the ~ollowing description Or the invention with re~erence to -the accompanying drawings 7 in which:
Fig. 1 is a longi-tudinally sectioned view showing a cup assembly contaîning a powder or green compact thereof -to be sintered;
F'ig, 2 is the same view showlng a modi~ication o~ a GUp a9sembly;
Fig. 3 is the sarne view of still another modirication o~ a cup assembly; and Figo 4 is the same view illustrating a further ~ -modification of a cup assembly.
Throughout the drawings~ similar parts and elements are denoted by the similar reference numerals and letters.
Re~erring now to Figs. 1 and 2, the numeral 1Q
designates a cylindrical cup, in which is contained a powdered material A to be sintered. The material may be powder or green compact made by cold-pressing the powder.
On an opening Or the cup 10 is put a vent member 11 made of solder to permit the air to pass. A lid 12 is put on said solder member 11 thereby allowing ventilation between the interior and exterior of the cup 10.
Said vent member 11 may be a net or screen made o~
S2~'~
1 soldar wires as illustrated in ~ig. 1, or may be a corrugated ~;
plate as shown in Fig. 2. Though not shown in the drawings, the member 11 can be a split ring made of solder wire, and it is p-ut on the opening of the cup 10. Further the member 11 may be a powdered solder, which is coated on the opening o~ the cup 10. There can be used an-y other solder member which permits ventilation.
Said material A to be sintered is diamoncl~ cubic boron nitride or their mixture. A suitable binder such as nickel and titanium nitride can be further mixed in the material.
If such material has a particle size o~ several microns or finer~ or if the material is mixed with a binder such as nickel powder, other metal powder, titanium nitride powder and other compound powder, it can be previously cold--pressed under a pressure ranging from several ten to several thousand Kg/cm2 to ~orm a green compact.
There can be used any other powdered materials to be sintered such as alumina, mix Or tungsten carbide with cobalt, and titanium diboride.
The combination Or the solder member 11 and the cup 10 along with the lid l2 is exemplified in Table I.
TABLE I
Cup and Lid Solder Member ~'e or its alloy Gu or its alloy Mo or its alloy Cu or its alloy Ti or its alloy silver solder WC Co or W-C~Co eutectic alloy W Cu alloy ~-~
W Ni alloy The above combination is selected in view o~ a temperature - 5 - -~
~5;2~
1 for the comple-tion of degassing a powdered material to be sintered, and in view Or the reactivity to the material.
Among the above, the combination of ~e or its alloy with Cu or its alloy is the most ine~pensive and easiesk in technical operation~
In the abova ernbodiment, the vent member 11 is inser-ted between the cup 10 and lid 12. However, as shown in Figs. 3 and 4) the lid 12 itself can be formed by a porous material such as sintered mass Or iron powder ;;
to permit ventilation, and thereon i9 put a solder piece 13.
The lid may be fitted in the opening o~ the cup 10 as appears from Fig. l~.
Thou~h not shown in the drawings, the whole cup 10 or a part thereof' can be formed by a porous material such as sin-tered iron powder. In the case, a solder piece is put adjacent the porous portion.
The following Table II e~empliries the combination of the cup 10~ lid 12 and solder piece 13.
TABI.E II
Cup Lid Solder Piece Ni sintered ~e powcler Cu alloy Fe or its alloy sintered Fe powder Cu alloy or Sn-Pb solder cold-pressed WG powder cold~pressed WC powder Co-C-W or Ni Co sintered Fe powder Cu al]oy cold-pressed Fe powder cold-pressed Fe powder Cu Prererably these porous materials have a porosity Or 20 to 60 ~.
Thus constructed cup assembly is than subiected to heat as well as vacuum so as to completely degas -the powdered material A, and the solder member 11 or solder piece 13 is melted at its mel-ting point by the continuation ~ 6 -~5~2 of heating to air-tightly seal the cup 10. In the cases of Fiys. 1 and 2, the lid 12 is brazed to the cup 10 by the solder member 11. In the cases of Figs. 3 and 4, the melted solder piece 13 permeates into the porous lid 12, which is in turn brazed to the cupr thereby air tightly sealing the cup 10.
Preferable hea-ting temperature is at least 500C or h:i~her. If the material to be sintered is diamond or cubic boron nitride which is thermodynamically unstable under ordinary pressure and transEorms to graphite or hexagonal boron nitride, 10 respectively, when exposed to high temperature, a lower tem-perature than 1300 C is preferable.
The vacuum is at least 10 2 mmHy or higher, and can be applied to a limited part having ventilation, for example, a-t the opening of the cup 10 through a pipe connected thereto.
The obtained cup is compressible under high pressure at high temperature while main-taining the air-tight seal.
The cup is then hot-pressed by hot isostatic press or super-pressure and hlgh temp~rature apparatus for making a diamond so as to obtain a sintered compact. If the material ~O to be sintered is diamond or high pressure form o~ boron nitride, it is preferable to hot-press under a pressure o~ at least 20 Kb or more at a temperature higher than 1000C for several minutes to several hours. As for the other materials such as alumina, titanium diboride and mix of -tungsten carbide with cobalt~ the pressure is several ten to several thousand Kg/cm2 and the temperature is 1200 to 2000C
The cup thus compressed by the hot-pressing includes a sintered compact and a shell enclosing it. The compact is obtained by removing the shell.
The specific gravit~ of WC 10 ~ Co alloy is 14.6.
Therefore, the weight of 1 cc thereof is 14.6 g. Assuming ,~
that the po-wder mix has an amount of -5 ~ ~ 2;
11~.6 x 0.005 x 1/32 x 22.4 x 103 = 51,1(cc) The powder mix is then hot-pressed by means of hot isostatic ~s~
1 press under a pressu:re of 2000 atm at a temperature of 1400 C, and this amoun-t o:~ 51.1 cc becomes;
51.1 x 1/2000 x 1673/29~(room temperatu:re) = o. 14 tcc ~s a result, WC-10 ~ Co compac-t must contain 1~ ~ o~ pore.
Therefore 9 it is a'bsolutel-y impossible to o'btain a compact havi.ng a density of 100 '~
In the case of super-pressure and high temperature apparatus for making a diamond, the material to be sin-tered is enclosed in a solid pressure medium such as pyrophyllite, and since a tremendous pressure such as 500 to 600 ~g/mm2 is applied to -the pressure medium, the escape o~ gases is almost impossib].e, simi]arly ln an air-tight container.
There~ore, when sintering diamond or cubic(i.e. isometric) boron nitride, which is becoming a recent issue, there ari.ses the same problem as WC-Co powder mix men-tioned above.
Upon sintering alumina powder, also the same problem occurs When the powder material is subjected to gas analysis, there is o~-ten genera-ted a gas as much as 1 ~.
According to the present inventi.on, there is proposed a process o~ producin.g a sin-tered compact comprisirlg filling a cup with a powdered material to be sin-tered, putting on an opening o:~ the cup a coveri.ng member includin~ a lid and solder so as to permit ventilation between the interior and e~terior o.~ the cup to ~orm a cup assemblyg applying heat as well as vacuu~ to the cup assembly to degas the powdered material~ melting the solder by the co~tinuation o:~ heatlng to air-tightl-y seal the cup with the lidg and hot-pressing the cup to obtain a sintered compact.
~ccordingly, it is an object of the present invention to provide a process o.~' producing a sintered compact making it possible to obtain a densely concentrated structure by ,.~ . -. . ", , .. : .. .
52~
1 co~lpletely degassing a powdered materia] so a~ to eliminate pores caused b-,y gases.
It is another ob,jec-t of the present invention to provide an effective process ~or ob-taining with certaint~
a dense compact by air-tightly sea:Ling a cup containing a powdered material during degassing without using any speci~ic device.
Other objects and ~eatures Or the present invention - will be apparent from the ~ollowing description Or the invention with re~erence to -the accompanying drawings 7 in which:
Fig. 1 is a longi-tudinally sectioned view showing a cup assembly contaîning a powder or green compact thereof -to be sintered;
F'ig, 2 is the same view showlng a modi~ication o~ a GUp a9sembly;
Fig. 3 is the sarne view of still another modirication o~ a cup assembly; and Figo 4 is the same view illustrating a further ~ -modification of a cup assembly.
Throughout the drawings~ similar parts and elements are denoted by the similar reference numerals and letters.
Re~erring now to Figs. 1 and 2, the numeral 1Q
designates a cylindrical cup, in which is contained a powdered material A to be sintered. The material may be powder or green compact made by cold-pressing the powder.
On an opening Or the cup 10 is put a vent member 11 made of solder to permit the air to pass. A lid 12 is put on said solder member 11 thereby allowing ventilation between the interior and exterior of the cup 10.
Said vent member 11 may be a net or screen made o~
S2~'~
1 soldar wires as illustrated in ~ig. 1, or may be a corrugated ~;
plate as shown in Fig. 2. Though not shown in the drawings, the member 11 can be a split ring made of solder wire, and it is p-ut on the opening of the cup 10. Further the member 11 may be a powdered solder, which is coated on the opening o~ the cup 10. There can be used an-y other solder member which permits ventilation.
Said material A to be sintered is diamoncl~ cubic boron nitride or their mixture. A suitable binder such as nickel and titanium nitride can be further mixed in the material.
If such material has a particle size o~ several microns or finer~ or if the material is mixed with a binder such as nickel powder, other metal powder, titanium nitride powder and other compound powder, it can be previously cold--pressed under a pressure ranging from several ten to several thousand Kg/cm2 to ~orm a green compact.
There can be used any other powdered materials to be sintered such as alumina, mix Or tungsten carbide with cobalt, and titanium diboride.
The combination Or the solder member 11 and the cup 10 along with the lid l2 is exemplified in Table I.
TABLE I
Cup and Lid Solder Member ~'e or its alloy Gu or its alloy Mo or its alloy Cu or its alloy Ti or its alloy silver solder WC Co or W-C~Co eutectic alloy W Cu alloy ~-~
W Ni alloy The above combination is selected in view o~ a temperature - 5 - -~
~5;2~
1 for the comple-tion of degassing a powdered material to be sintered, and in view Or the reactivity to the material.
Among the above, the combination of ~e or its alloy with Cu or its alloy is the most ine~pensive and easiesk in technical operation~
In the abova ernbodiment, the vent member 11 is inser-ted between the cup 10 and lid 12. However, as shown in Figs. 3 and 4) the lid 12 itself can be formed by a porous material such as sintered mass Or iron powder ;;
to permit ventilation, and thereon i9 put a solder piece 13.
The lid may be fitted in the opening o~ the cup 10 as appears from Fig. l~.
Thou~h not shown in the drawings, the whole cup 10 or a part thereof' can be formed by a porous material such as sin-tered iron powder. In the case, a solder piece is put adjacent the porous portion.
The following Table II e~empliries the combination of the cup 10~ lid 12 and solder piece 13.
TABI.E II
Cup Lid Solder Piece Ni sintered ~e powcler Cu alloy Fe or its alloy sintered Fe powder Cu alloy or Sn-Pb solder cold-pressed WG powder cold~pressed WC powder Co-C-W or Ni Co sintered Fe powder Cu al]oy cold-pressed Fe powder cold-pressed Fe powder Cu Prererably these porous materials have a porosity Or 20 to 60 ~.
Thus constructed cup assembly is than subiected to heat as well as vacuum so as to completely degas -the powdered material A, and the solder member 11 or solder piece 13 is melted at its mel-ting point by the continuation ~ 6 -~5~2 of heating to air-tightly seal the cup 10. In the cases of Fiys. 1 and 2, the lid 12 is brazed to the cup 10 by the solder member 11. In the cases of Figs. 3 and 4, the melted solder piece 13 permeates into the porous lid 12, which is in turn brazed to the cupr thereby air tightly sealing the cup 10.
Preferable hea-ting temperature is at least 500C or h:i~her. If the material to be sintered is diamond or cubic boron nitride which is thermodynamically unstable under ordinary pressure and transEorms to graphite or hexagonal boron nitride, 10 respectively, when exposed to high temperature, a lower tem-perature than 1300 C is preferable.
The vacuum is at least 10 2 mmHy or higher, and can be applied to a limited part having ventilation, for example, a-t the opening of the cup 10 through a pipe connected thereto.
The obtained cup is compressible under high pressure at high temperature while main-taining the air-tight seal.
The cup is then hot-pressed by hot isostatic press or super-pressure and hlgh temp~rature apparatus for making a diamond so as to obtain a sintered compact. If the material ~O to be sintered is diamond or high pressure form o~ boron nitride, it is preferable to hot-press under a pressure o~ at least 20 Kb or more at a temperature higher than 1000C for several minutes to several hours. As for the other materials such as alumina, titanium diboride and mix of -tungsten carbide with cobalt~ the pressure is several ten to several thousand Kg/cm2 and the temperature is 1200 to 2000C
The cup thus compressed by the hot-pressing includes a sintered compact and a shell enclosing it. The compact is obtained by removing the shell.
3~ If a diamond compact obtained has its matrix mainly composed of copper, it is non-magnetic and useful as an-ti-.".., ' . ~ . . ..
.. ,., ,, .- . .
1 abrasive parts ~nd el0ments in an electronic computer and household electric machines such as tape recorder. l~oreover it has a property higher in heat conductivity. However, it may generall~ be lower in toughness as compar~d to one with a matrix of iron ~roup element. Especially, when used as a cutting tip, the strength is not sufficient at high temperature since the melting point O:e the copper is lower than that of iron group element.
In contras-t, a diamond compact with its rnatrix mainly composed of nickel or its alloy has properties substan-tially opposite to the above. '~
As a result of experimen-ts, the former is obtained by the use of iron or cobalt cup in combination with a solder of copper or its alloy, while the latter can be obtained b~ the use of a cup of nickel or its alloy in combination with a solder of copper or its allo~
As mentioned before, the hot-pressed cup includes a sintered compact enclosed by a shell of compressed cup.
In order to obtain a compact, the~shell should be removed.
However~ this is very difficult, particularly in the case of small compact such as diamorld, since the shell is generally in ti~ght engagement wit'h the compact. However7 with a cup of iron or its alloy, it has been found that the shell can be readily taken off~
U-tilizing the a'bove phenomenon, when putting~ for exarnple, a conical block of iron on the center of the bottom of iron cup, a diamond compact having a conical recess at the center thereof can be obtained with ease since the conical block is readily taken off. Therefore, there can be provided a diamond compact having a suitable shape similar to a :einished product such as wire drawing ~ 8 --"
2~.~
1 die. Of course, an iron rod and the like can he put in the c~p. Considering the di-fficulty of shaping a dlamond compact, this is very useEul.
In order to more clearly illustrate the present invention, re~erence is now to be made to -the following Examples, which are only for description rather than limitation to the invention.
~ cup o~ mild steel was vibrated while it was fillecl with diamond powder. The cup had an outer diameter of 14 mm, inner diameter of 7 mm and height of 19 mm and the diamond powder had an average particle size of 5 micron. The amount of diamond was 1.6 g~
On an opening o~ the cup was put, as a solder, a split ring of pure copper wire with a diameter of 1~5 mm, and thereon was put a lid of mild steel having a diameter of 14 mm and thickness of 3 mm.
Thus assembled cup was put in a vacuum furnace, heated to 1150C by a rising rate of 500C per hour in a vacuum of 2~ 10 4 mmHg, held for 10 minutes, and cooled. The cup taken out of the furnace had its opening air--tigh-tly sealed by the melted copper.
This was hot~pressed by a super-pressure and high temperature apparatus for making a diamond. Initially, the cup was put in the apparatus, given a pressure of 55 Rb, then heated to 1450C, held at the temperature fox 5 minutes, and cooled.
Tha steel cup was then ground and removed to take out ~;
a diamond compact, the specific gravity of which was 4Ø The compact was densely sintered without any pore.
The compact was further ground by a diamond wheel dresser. As a result of examination by microscope, the _ 9 _ 5~
l structure was such that -the grains of diamond powder were bonded together, and grain boundaries therebetween were f`i]led with rnatal. By the analysis of X-ray microanalyzerJ
i-t was revealed that this bonding metal consis-ted of copper an(l about 15 '~ Or iron.
3efore hot-pressing, the air-tightly sealed cup was cut -to find that the inner periphery thereof was ~ilmed with copper for 'brazing the lid to the cup, the thickness of copper filrn being a'bout 0.15 mm. The coppar and steel of the cup were considered to permeate into the grain boundaries of diamond powder to form a metal matrix.
Cubic boron nitride powder having average particle size of' 4 micron and titanium nitride powder having average particle size of 1 micron were mixed in a volume ratio of 3 : 2, and filled in a cup of molybdenum having an outer diameter of 14 mm, inner diameter of 10 mm and height of 6 mm.
On an opening of the cup was put~ as a solder, a screen of 32 mesh(hereinafter re~erred -to as U.S. Standard) made of bronze, the screen having a diameter of 1 Ll. InmJ on which was put a lid of moly'bdenum with a diameter o~ 14 mm and thickness of 3 mm.
Thus assembled cup was put in a vacuum furnace in the same manner as Example 1, heated at 1100 G in a vacuum of 10-l~ mmHg, and cooled. The lid and cup taken ou-t of the furnace were air-ti.ghtly brazed together by the melted bronze.
This cup was hot-pressed by the super pressure apparatus in the same manner as Example 1. The obtained compact exhibited Vickers hardness of 3600, and was densely sinteredO
5~
Instead of mol~bdenum cup of E'xample 2, there was prepared a Cllp of pure titanium having the same dimensions.
Then, a diamond powder having average particle size Or 5 micron was mixed with 19 weight ~ of electrolytic copper powder and 3.5 weight i~ of nickel powder~ respectively having a particle size Or -325 mesh. Ths m;x was ball-milled in a stainless steel pot b~ using cemented carbide balls~ and filled in said titanium cup~
On an opening O:e the cup was pu-t a split ring o~ silver solder(corresponding to JIS - Japanese Industrial S-tandard~
BAg-2, melting point 700 C), on which was laid a lid of titanium.
Similarly to Example 1, the cup assembl~ was put in a vacuum furnace9 heated to 900 C in a vacuum of 10~L~r~lHg, and cooled. The cup taken out of the furnace was air-tightly sealed with the melted silver solder.
'rhe cup was pressed under a pressure of 60 ~b by means of -the same super-pressure apparatus as Example 1, and then the temperature was raised to 1500 C. The Cllp was held at the temperature f'or 5 minutes to be hot-pressed.
The CUp was takerl out, and ground to obtain a densely sin-tered diamond compact. This was cu-t by a diamond cutter and a piece was 'orazed to a tool shank b~ using a silver solder to f'orm a cutt;ng tool.
A cemented carbide rod of WC-l2 ~ Co with Vickers hardness of 1300 was cut b~ said cutting tool) resulting in a sat;sfactor~ performance.
h powdered -titani-um diboride(TiB2) having average particle size of' 3 micron was filled in a titanium cup - 11 - : '"
. " ~:
9S2~2 1 having an outer diameter of 1L~r~rn, inner diameter Or 1 0 mm and height of 6 mm.
A powder of nickel solder(melting point: 102L~ C, particle size: --120 nnesh, +200 mesh) consisting of Ni-ll.5 Si-2.9 ~ was added with~ as a ~inding agent, ethyl cellulose solved in toluene, and a~itated. This was coated on an opening ol' the cup in a thic1rness of about 3 rnm, on which was put a tantalum lid having a thickness of 2 mm.
In the same manner as Example 1, the cup asse~'bl-g was put in a vacuu~ furnace, hea-ted to 1100 C in a vacuum of 10-1~ mmHg, and eooled.
As a result of examination on the cup taken Ollt of' the furnace, the tantalum lid was brazed to the cup wi-thout an~ gap.
The cup was put in a super-pressure apparatus 3 pressed to 50 Kb, and heated at 1800 C for 10 mimltes to be hot-pressed.
The obtained eompaet had a density as nnueh as 99 ,~
of ideal density. As a result o~ examina-tion on the structure after polishin~ the compact by diamond paste, lt was assured tha-t the eon1pact was densel-y sintered without any pore.
Diamond powder of average particle size of 5 micron added wi-th 20 weight ~ of carbonyl niekel powder was ball-milled and mixed for 24 hours în a sta;nless steel pot by using cemented earbide balls of WC-10 -~ Co. The powder mix was added with 2 '~ of camphor as a lubricant, and cold-pressed undsr a pressure of 1 t/cm2 to f'orm a pellet having a diarneter of 5 mrn and height of 5 rnrn.
2~
1In a cu-p of` nickel having an inner diame-ter o~ 5 mm, outer diameter of 7 mm was put the pellet, on wh;.ch was put a porous lid having a dia-rneter of 5 mm made of sintered iron powder with a particle slze from 120 mesh to 100 mesh, on which was laid a copper allo~ con-taining 5 '~ of iron and 5 ~ of manganese, th.e allo.y havin~ a diam~ter of 2.5 mm ~ -and height of 2 mm.
The cup as~embly was put in a vacuum furnace wi-th ::
a diffusion pump, heated to 1150 C by a rising rate of 500 C per hour, and cooled~ Taking the cup out of the furnace J the melted copper alloy completel-y permeated i.nto th.e porous lid~ which was in turn brazed to the nickel cup.
This was hot-pressed by means of a super-pressllre and high tempe:rature apparatus for making a diamond.
Graphite was used as a heating element, and salt was ~ -.
interposed between the graphi-te and nickel cup. The cup was hot-pressed under a pressure of 60 Kb at a temperature :~:
of 1600 C for 10 minutes to obtain a diamond compact having Vickers hardness of 6500. The densi-ty as well as hardness was much superior to that obtained. by a conventional process without the degassing treatment as in the preseni;
invention.
Super-puritly alumina powder having average particle size of 0.4 micron was added wi-th o.5 ~ of magnesia powder, and subjected to a wet ball-milling in water for 100 hours in a po-t having super-purit-y alumina lining by using super-purity alumina balls. The powder wad dried, added with 3 % of camphor, and cold-pressed under a pressure of 1 t~cm to form a green compact having a diameter of 60 mm and height of 50 mm.
1~¢~
1 i On the other hand, there was prepared a cup having an inner diame-ter o~ 60 mm, depth o~ 70 mm and thickness of 1 mm by cutting a low carbon steel block. In the cup was inserted said green compact~ on which wa~-pu-t a porous lid having a diameter o~ 60 mm and thickness o~ 1 mm made of sintered iron powder with a particle size ~rom 100 mesh to 50 mesh, on which was laid a copper alloy containing 5 ~ of iron and 5 ~ of manganese.
The cup assembly was put in a vacuum furnace with a diffusion pump, and heated to 1150 C by a rising rate of 200 C per hour.
Taking the cup out of the furnace, the copper alloy co~pletely permeated in-to the porous iron lid and sealed the opening o~ the cup. Then a disc of low carbon steel having a diameter of ~0 mm and thickness of 1 mm wa3 brazed to the opening of the cup 90 that the whole periphery o~ the cup was surrounded by the low carbon steel.
This was hot-pressed in an atmosphere of argon gas ` under a pressure of 2000 atm at a temperature of 1400 C
~or one hour by means o~ hot isostatic press.
The metal surrounding the cup taken out of the press was removed by using HN03 to obtain an aIumina compact.
The surface thereof was ground o~ in a thickness o~ several mm to obtain a compact as dense as 99 ~ o~ ideal density ~-(P = 3.99 g/cc).
As a result of examination on crystal particles by electron microscope, they were about o.8 micron much finer than those obtained by any other conventional processes.
3o A cup was formed by a cylindrical member and a bot-tom lid ~itted therein, both being made by cold pressing ., ., "., ~, " .", , ~ . .
\
;2~2 1 WC powder with average particle slze of' 4 micron. The Cllp had a -thickness of 2 mm, inner diameter of 5 mm and inner depth of 2 mm. Also a top lid having a thiclmess of 10 mm was prepared by the same material.
In the cup was inserted a green compact of powder mix comprising cubic boron nitride and ~0 ~ of -titani~n ni-tride J on which was put the top lid7 on which was laid a mass of cold~pressed powder rni~ consisting of Co-C-W
so as to form an eutectic alloy~
The cup assemhly was subjected to the same degassing treatment as Example 5 in a vacuum furnace, except that ;
the highest temperature was 1350 c. After grinding off the surface of the Cllp taken out of the furnace so as to eliminate roughness on the surface~ the cup was subjected to the hot-pressirlg in the ~ame manner as F~ample 5 to obtain a sintered body having a diameter of about 10 mm and thickness of about 6 mm. This was ground to remove WC-Co a]loy at the side face and upper face to obtain a cubic boron nitride compact hav:;ng a eemen-ted carbide as a substrate. This shape was very useful as a tip of a cutting tool.
E~AMPLE 8 Instead of nickel cup of Example 5, a cup was made from tungsten powder having particle size of 10 micron, and ins-tead of copper alloy of Example 5, nickel was used.
The highest temperature in the vacuum ~urnace was 1 500 c.
Similarly, a compact sufficierltl~ sintered was obtained.
A cup having an inner diameter of 5 mm, outer diameter of 8 mm and depth of 10 mm was formed by eutting carbon - 15 ~
~s~
1 steel. A dlamond powder having particle size finer -than 400 mesh was ~illed in the CUp in a height of 8 mrrlJ while giving vibra-tion, and thereon was pu-t a porous lid made b~J sintering iron powder o~ -~140 mesh to -100 mesh, on which was further laid a piece of copper allog incl-uding 5 ~ o~ iron and 5 '~ of manganese.
The cup assembl-y was put in a vacuum furnace with a diffusion pump, and heated -to 11~0 C by a rising rate of 500 C per hour.
Taking the cup out o~ the furnace, the copper alloy permeated into the porous iron lid, which was in turn brazed to the steel cup.
This was hot-pressed b;q means o~ a super-pressure and high temperature apparatus for making a diamond. As a hea-ting e:Lement was used a graphlte tube, and salt was interposed between the tube and cup. Further as a pressure mediu-m was used a pyrophyllite.
Initially, the pressure was raised -to 60 Kb, and then the -temperature to 1600 C by gradually supplying electrical curren-t. Therearter the pressure as well as temperature was lowered. The obtaizled compact was such that the diamond par-ticles were completely impregna-l;ed with copper and presented good appearance. Vickers hardness thereof was about 6000~
Instead of -the steel GUp 0.~ Example 9, 18~8 stainless steel, nickel or cobalt was used, respectively. Each cup was subjected to the same treatment as Example 9, with the same result as Example 9.
EX~MPLE 11 Atomized iron powder was cold-pressed to form a cup " :" ~
z 1 having a porosit-y Oe 37 ~. The dimensions of the cup were the same as Example ~. After rilling diamond powder of -l~00 mesh in -the cup, a lid formed with the same material as the cup was ~itted in the cup, and thereon were accumulated copper wires Cllt into pieces, the wires having a diameter of 1 mm.
The cup assembly was put in the same vacuum furnace as Example 9, and heated, while supplying hydrogen gas for the reduction of oxides on the surfaces o~ iron and diamond ~;
powders till the temperature was raised to 9~0 C, the pressure o~ hydrogen gas in the ~'urnace being held at 300 mmHg. After raising the temperature to 950 C, the furnace was held under a pressure o~ lO l~ to 10 5 mmHg by the use of di~fusion pump.
The cup was then ho-t-pressed by a super-pressure a-pparatus in the same manner as Example 9 to obtain a densely sintered compact~
A cup having an inner diameter Oe 5 mm, outer diameter Oe 8 mm and dep-th of 10 mm was formed b;y cutting a nickel rod. In the cup was filled a diamond powder o~
-400 mesh in a height of 8 mm, and thereon was laid a porous lid having a diameter o~ 5 mm and thlckness o~ 1 mm made b;y sintering iron powder of ~140 mesh and -100 mesh, on which was further put a copper piece.
The cup assembly was put in a vacuum eurnace wlth a diffusion pump, and heated to 1150 C b-y a rising rate O.e 500 C per hour. Thereafter 7 this was hot-pressed by means of super-pressure and high temperature apparatus for making a diamond. As a heating element was used a graphite tube, and as an electrical insulation material wa~ put a salt _ ~7 _ ~0~ 2 1 between the cup and tube. L~urther as a pressure medium was use~ a pyrophyllite. Initially, the pressure was raised -to 60 Kb, and then the temperature to 1500 C by gradually suppl~ing electrical current~ The cup was held at the temperature for 5 minutes.
The 0'3 tained compac-t was crushed by compression and examined by a mlcro~cope to find no pore at the broken face.
As a result of analysis b~ an X-rag microanalyzer, solely nickel was observed.
A diamond powder of +300 mesh and -200 rnesh was used in place o-~ the powder Or Example 12. F'urther instead o~ the solder piece of Example 12, a solder piece o~
Cu-40 ~ Ni alloy was used.
The cup assembly was treated in vacuum in the same manner as Fxample 12 except that the highest temperature was 1300 C.
The obtained compact had a matrix mainly composed of nickel arld was densely sintered.
EXA~PLE 1L~
There were used diamond powder having particle size ranging from 2 to 3 micron and a solder piece of Cu-20 '~ Mn alloy, in places of the powder and solder piece of Example 12.
The cup assembly was treated in vacuum in the same manner as F~ample 12, excep-t that the highe3t temperature was 950 C.
The obtained compact had a ma-trix mainly composecl o~ n;ckel, and was densely sîntered.
3 In Example 12, thc ho-t-pressing was performed at a temperature Or 1400 C, 1500 C ancl 1600 C, respectively.
The compact obtained at 1400 C had a specific gravity of 1 3.86. However~ as -the -temperature rose, the gravity increased linearlq, and at 1600 C it was L~00. Also the nickel amoun-t in the matrix increased as the -temperature rose.
Instead of the porous lid o.f Example 12, a porous lid made by sintering Co powder was used, the cup having -the same dimension~. In the same manner as Example 12, there was obtained a sintered compact, which exhibited good result similar to that of Example l2.
As described hereinbefore in detail$ according to the present invention, a sintered compact having no pore can be efficiently and sure].y obtained since a powdered material to be sintered is completely degassed by the application of heat as well as vacuum to a cup filled with the material and at the same time a solder put on the opening of the Cllp iS melted by said heat so as to air~
tightl.~J seal the Cllp, which is compressible under high pressure at high temperature during hot-pressing while maintaining the air tight seal.
.~,,. : :
,, - ~. ~ - ~ ,
.. ,., ,, .- . .
1 abrasive parts ~nd el0ments in an electronic computer and household electric machines such as tape recorder. l~oreover it has a property higher in heat conductivity. However, it may generall~ be lower in toughness as compar~d to one with a matrix of iron ~roup element. Especially, when used as a cutting tip, the strength is not sufficient at high temperature since the melting point O:e the copper is lower than that of iron group element.
In contras-t, a diamond compact with its rnatrix mainly composed of nickel or its alloy has properties substan-tially opposite to the above. '~
As a result of experimen-ts, the former is obtained by the use of iron or cobalt cup in combination with a solder of copper or its alloy, while the latter can be obtained b~ the use of a cup of nickel or its alloy in combination with a solder of copper or its allo~
As mentioned before, the hot-pressed cup includes a sintered compact enclosed by a shell of compressed cup.
In order to obtain a compact, the~shell should be removed.
However~ this is very difficult, particularly in the case of small compact such as diamorld, since the shell is generally in ti~ght engagement wit'h the compact. However7 with a cup of iron or its alloy, it has been found that the shell can be readily taken off~
U-tilizing the a'bove phenomenon, when putting~ for exarnple, a conical block of iron on the center of the bottom of iron cup, a diamond compact having a conical recess at the center thereof can be obtained with ease since the conical block is readily taken off. Therefore, there can be provided a diamond compact having a suitable shape similar to a :einished product such as wire drawing ~ 8 --"
2~.~
1 die. Of course, an iron rod and the like can he put in the c~p. Considering the di-fficulty of shaping a dlamond compact, this is very useEul.
In order to more clearly illustrate the present invention, re~erence is now to be made to -the following Examples, which are only for description rather than limitation to the invention.
~ cup o~ mild steel was vibrated while it was fillecl with diamond powder. The cup had an outer diameter of 14 mm, inner diameter of 7 mm and height of 19 mm and the diamond powder had an average particle size of 5 micron. The amount of diamond was 1.6 g~
On an opening o~ the cup was put, as a solder, a split ring of pure copper wire with a diameter of 1~5 mm, and thereon was put a lid of mild steel having a diameter of 14 mm and thickness of 3 mm.
Thus assembled cup was put in a vacuum furnace, heated to 1150C by a rising rate of 500C per hour in a vacuum of 2~ 10 4 mmHg, held for 10 minutes, and cooled. The cup taken out of the furnace had its opening air--tigh-tly sealed by the melted copper.
This was hot~pressed by a super-pressure and high temperature apparatus for making a diamond. Initially, the cup was put in the apparatus, given a pressure of 55 Rb, then heated to 1450C, held at the temperature fox 5 minutes, and cooled.
Tha steel cup was then ground and removed to take out ~;
a diamond compact, the specific gravity of which was 4Ø The compact was densely sintered without any pore.
The compact was further ground by a diamond wheel dresser. As a result of examination by microscope, the _ 9 _ 5~
l structure was such that -the grains of diamond powder were bonded together, and grain boundaries therebetween were f`i]led with rnatal. By the analysis of X-ray microanalyzerJ
i-t was revealed that this bonding metal consis-ted of copper an(l about 15 '~ Or iron.
3efore hot-pressing, the air-tightly sealed cup was cut -to find that the inner periphery thereof was ~ilmed with copper for 'brazing the lid to the cup, the thickness of copper filrn being a'bout 0.15 mm. The coppar and steel of the cup were considered to permeate into the grain boundaries of diamond powder to form a metal matrix.
Cubic boron nitride powder having average particle size of' 4 micron and titanium nitride powder having average particle size of 1 micron were mixed in a volume ratio of 3 : 2, and filled in a cup of molybdenum having an outer diameter of 14 mm, inner diameter of 10 mm and height of 6 mm.
On an opening of the cup was put~ as a solder, a screen of 32 mesh(hereinafter re~erred -to as U.S. Standard) made of bronze, the screen having a diameter of 1 Ll. InmJ on which was put a lid of moly'bdenum with a diameter o~ 14 mm and thickness of 3 mm.
Thus assembled cup was put in a vacuum furnace in the same manner as Example 1, heated at 1100 G in a vacuum of 10-l~ mmHg, and cooled. The lid and cup taken ou-t of the furnace were air-ti.ghtly brazed together by the melted bronze.
This cup was hot-pressed by the super pressure apparatus in the same manner as Example 1. The obtained compact exhibited Vickers hardness of 3600, and was densely sinteredO
5~
Instead of mol~bdenum cup of E'xample 2, there was prepared a Cllp of pure titanium having the same dimensions.
Then, a diamond powder having average particle size Or 5 micron was mixed with 19 weight ~ of electrolytic copper powder and 3.5 weight i~ of nickel powder~ respectively having a particle size Or -325 mesh. Ths m;x was ball-milled in a stainless steel pot b~ using cemented carbide balls~ and filled in said titanium cup~
On an opening O:e the cup was pu-t a split ring o~ silver solder(corresponding to JIS - Japanese Industrial S-tandard~
BAg-2, melting point 700 C), on which was laid a lid of titanium.
Similarly to Example 1, the cup assembl~ was put in a vacuum furnace9 heated to 900 C in a vacuum of 10~L~r~lHg, and cooled. The cup taken out of the furnace was air-tightly sealed with the melted silver solder.
'rhe cup was pressed under a pressure of 60 ~b by means of -the same super-pressure apparatus as Example 1, and then the temperature was raised to 1500 C. The Cllp was held at the temperature f'or 5 minutes to be hot-pressed.
The CUp was takerl out, and ground to obtain a densely sin-tered diamond compact. This was cu-t by a diamond cutter and a piece was 'orazed to a tool shank b~ using a silver solder to f'orm a cutt;ng tool.
A cemented carbide rod of WC-l2 ~ Co with Vickers hardness of 1300 was cut b~ said cutting tool) resulting in a sat;sfactor~ performance.
h powdered -titani-um diboride(TiB2) having average particle size of' 3 micron was filled in a titanium cup - 11 - : '"
. " ~:
9S2~2 1 having an outer diameter of 1L~r~rn, inner diameter Or 1 0 mm and height of 6 mm.
A powder of nickel solder(melting point: 102L~ C, particle size: --120 nnesh, +200 mesh) consisting of Ni-ll.5 Si-2.9 ~ was added with~ as a ~inding agent, ethyl cellulose solved in toluene, and a~itated. This was coated on an opening ol' the cup in a thic1rness of about 3 rnm, on which was put a tantalum lid having a thickness of 2 mm.
In the same manner as Example 1, the cup asse~'bl-g was put in a vacuu~ furnace, hea-ted to 1100 C in a vacuum of 10-1~ mmHg, and eooled.
As a result of examination on the cup taken Ollt of' the furnace, the tantalum lid was brazed to the cup wi-thout an~ gap.
The cup was put in a super-pressure apparatus 3 pressed to 50 Kb, and heated at 1800 C for 10 mimltes to be hot-pressed.
The obtained eompaet had a density as nnueh as 99 ,~
of ideal density. As a result o~ examina-tion on the structure after polishin~ the compact by diamond paste, lt was assured tha-t the eon1pact was densel-y sintered without any pore.
Diamond powder of average particle size of 5 micron added wi-th 20 weight ~ of carbonyl niekel powder was ball-milled and mixed for 24 hours în a sta;nless steel pot by using cemented earbide balls of WC-10 -~ Co. The powder mix was added with 2 '~ of camphor as a lubricant, and cold-pressed undsr a pressure of 1 t/cm2 to f'orm a pellet having a diarneter of 5 mrn and height of 5 rnrn.
2~
1In a cu-p of` nickel having an inner diame-ter o~ 5 mm, outer diameter of 7 mm was put the pellet, on wh;.ch was put a porous lid having a dia-rneter of 5 mm made of sintered iron powder with a particle slze from 120 mesh to 100 mesh, on which was laid a copper allo~ con-taining 5 '~ of iron and 5 ~ of manganese, th.e allo.y havin~ a diam~ter of 2.5 mm ~ -and height of 2 mm.
The cup as~embly was put in a vacuum furnace wi-th ::
a diffusion pump, heated to 1150 C by a rising rate of 500 C per hour, and cooled~ Taking the cup out of the furnace J the melted copper alloy completel-y permeated i.nto th.e porous lid~ which was in turn brazed to the nickel cup.
This was hot-pressed by means of a super-pressllre and high tempe:rature apparatus for making a diamond.
Graphite was used as a heating element, and salt was ~ -.
interposed between the graphi-te and nickel cup. The cup was hot-pressed under a pressure of 60 Kb at a temperature :~:
of 1600 C for 10 minutes to obtain a diamond compact having Vickers hardness of 6500. The densi-ty as well as hardness was much superior to that obtained. by a conventional process without the degassing treatment as in the preseni;
invention.
Super-puritly alumina powder having average particle size of 0.4 micron was added wi-th o.5 ~ of magnesia powder, and subjected to a wet ball-milling in water for 100 hours in a po-t having super-purit-y alumina lining by using super-purity alumina balls. The powder wad dried, added with 3 % of camphor, and cold-pressed under a pressure of 1 t~cm to form a green compact having a diameter of 60 mm and height of 50 mm.
1~¢~
1 i On the other hand, there was prepared a cup having an inner diame-ter o~ 60 mm, depth o~ 70 mm and thickness of 1 mm by cutting a low carbon steel block. In the cup was inserted said green compact~ on which wa~-pu-t a porous lid having a diameter o~ 60 mm and thickness o~ 1 mm made of sintered iron powder with a particle size ~rom 100 mesh to 50 mesh, on which was laid a copper alloy containing 5 ~ of iron and 5 ~ of manganese.
The cup assembly was put in a vacuum furnace with a diffusion pump, and heated to 1150 C by a rising rate of 200 C per hour.
Taking the cup out of the furnace, the copper alloy co~pletely permeated in-to the porous iron lid and sealed the opening o~ the cup. Then a disc of low carbon steel having a diameter of ~0 mm and thickness of 1 mm wa3 brazed to the opening of the cup 90 that the whole periphery o~ the cup was surrounded by the low carbon steel.
This was hot-pressed in an atmosphere of argon gas ` under a pressure of 2000 atm at a temperature of 1400 C
~or one hour by means o~ hot isostatic press.
The metal surrounding the cup taken out of the press was removed by using HN03 to obtain an aIumina compact.
The surface thereof was ground o~ in a thickness o~ several mm to obtain a compact as dense as 99 ~ o~ ideal density ~-(P = 3.99 g/cc).
As a result of examination on crystal particles by electron microscope, they were about o.8 micron much finer than those obtained by any other conventional processes.
3o A cup was formed by a cylindrical member and a bot-tom lid ~itted therein, both being made by cold pressing ., ., "., ~, " .", , ~ . .
\
;2~2 1 WC powder with average particle slze of' 4 micron. The Cllp had a -thickness of 2 mm, inner diameter of 5 mm and inner depth of 2 mm. Also a top lid having a thiclmess of 10 mm was prepared by the same material.
In the cup was inserted a green compact of powder mix comprising cubic boron nitride and ~0 ~ of -titani~n ni-tride J on which was put the top lid7 on which was laid a mass of cold~pressed powder rni~ consisting of Co-C-W
so as to form an eutectic alloy~
The cup assemhly was subjected to the same degassing treatment as Example 5 in a vacuum furnace, except that ;
the highest temperature was 1350 c. After grinding off the surface of the Cllp taken out of the furnace so as to eliminate roughness on the surface~ the cup was subjected to the hot-pressirlg in the ~ame manner as F~ample 5 to obtain a sintered body having a diameter of about 10 mm and thickness of about 6 mm. This was ground to remove WC-Co a]loy at the side face and upper face to obtain a cubic boron nitride compact hav:;ng a eemen-ted carbide as a substrate. This shape was very useful as a tip of a cutting tool.
E~AMPLE 8 Instead of nickel cup of Example 5, a cup was made from tungsten powder having particle size of 10 micron, and ins-tead of copper alloy of Example 5, nickel was used.
The highest temperature in the vacuum ~urnace was 1 500 c.
Similarly, a compact sufficierltl~ sintered was obtained.
A cup having an inner diameter of 5 mm, outer diameter of 8 mm and depth of 10 mm was formed by eutting carbon - 15 ~
~s~
1 steel. A dlamond powder having particle size finer -than 400 mesh was ~illed in the CUp in a height of 8 mrrlJ while giving vibra-tion, and thereon was pu-t a porous lid made b~J sintering iron powder o~ -~140 mesh to -100 mesh, on which was further laid a piece of copper allog incl-uding 5 ~ o~ iron and 5 '~ of manganese.
The cup assembl-y was put in a vacuum furnace with a diffusion pump, and heated -to 11~0 C by a rising rate of 500 C per hour.
Taking the cup out o~ the furnace, the copper alloy permeated into the porous iron lid, which was in turn brazed to the steel cup.
This was hot-pressed b;q means o~ a super-pressure and high temperature apparatus for making a diamond. As a hea-ting e:Lement was used a graphlte tube, and salt was interposed between the tube and cup. Further as a pressure mediu-m was used a pyrophyllite.
Initially, the pressure was raised -to 60 Kb, and then the -temperature to 1600 C by gradually supplying electrical curren-t. Therearter the pressure as well as temperature was lowered. The obtaizled compact was such that the diamond par-ticles were completely impregna-l;ed with copper and presented good appearance. Vickers hardness thereof was about 6000~
Instead of -the steel GUp 0.~ Example 9, 18~8 stainless steel, nickel or cobalt was used, respectively. Each cup was subjected to the same treatment as Example 9, with the same result as Example 9.
EX~MPLE 11 Atomized iron powder was cold-pressed to form a cup " :" ~
z 1 having a porosit-y Oe 37 ~. The dimensions of the cup were the same as Example ~. After rilling diamond powder of -l~00 mesh in -the cup, a lid formed with the same material as the cup was ~itted in the cup, and thereon were accumulated copper wires Cllt into pieces, the wires having a diameter of 1 mm.
The cup assembly was put in the same vacuum furnace as Example 9, and heated, while supplying hydrogen gas for the reduction of oxides on the surfaces o~ iron and diamond ~;
powders till the temperature was raised to 9~0 C, the pressure o~ hydrogen gas in the ~'urnace being held at 300 mmHg. After raising the temperature to 950 C, the furnace was held under a pressure o~ lO l~ to 10 5 mmHg by the use of di~fusion pump.
The cup was then ho-t-pressed by a super-pressure a-pparatus in the same manner as Example 9 to obtain a densely sintered compact~
A cup having an inner diameter Oe 5 mm, outer diameter Oe 8 mm and dep-th of 10 mm was formed b;y cutting a nickel rod. In the cup was filled a diamond powder o~
-400 mesh in a height of 8 mm, and thereon was laid a porous lid having a diameter o~ 5 mm and thlckness o~ 1 mm made b;y sintering iron powder of ~140 mesh and -100 mesh, on which was further put a copper piece.
The cup assembly was put in a vacuum eurnace wlth a diffusion pump, and heated to 1150 C b-y a rising rate O.e 500 C per hour. Thereafter 7 this was hot-pressed by means of super-pressure and high temperature apparatus for making a diamond. As a heating element was used a graphite tube, and as an electrical insulation material wa~ put a salt _ ~7 _ ~0~ 2 1 between the cup and tube. L~urther as a pressure medium was use~ a pyrophyllite. Initially, the pressure was raised -to 60 Kb, and then the temperature to 1500 C by gradually suppl~ing electrical current~ The cup was held at the temperature for 5 minutes.
The 0'3 tained compac-t was crushed by compression and examined by a mlcro~cope to find no pore at the broken face.
As a result of analysis b~ an X-rag microanalyzer, solely nickel was observed.
A diamond powder of +300 mesh and -200 rnesh was used in place o-~ the powder Or Example 12. F'urther instead o~ the solder piece of Example 12, a solder piece o~
Cu-40 ~ Ni alloy was used.
The cup assembly was treated in vacuum in the same manner as Fxample 12 except that the highest temperature was 1300 C.
The obtained compact had a matrix mainly composed of nickel arld was densely sintered.
EXA~PLE 1L~
There were used diamond powder having particle size ranging from 2 to 3 micron and a solder piece of Cu-20 '~ Mn alloy, in places of the powder and solder piece of Example 12.
The cup assembly was treated in vacuum in the same manner as F~ample 12, excep-t that the highe3t temperature was 950 C.
The obtained compact had a ma-trix mainly composecl o~ n;ckel, and was densely sîntered.
3 In Example 12, thc ho-t-pressing was performed at a temperature Or 1400 C, 1500 C ancl 1600 C, respectively.
The compact obtained at 1400 C had a specific gravity of 1 3.86. However~ as -the -temperature rose, the gravity increased linearlq, and at 1600 C it was L~00. Also the nickel amoun-t in the matrix increased as the -temperature rose.
Instead of the porous lid o.f Example 12, a porous lid made by sintering Co powder was used, the cup having -the same dimension~. In the same manner as Example 12, there was obtained a sintered compact, which exhibited good result similar to that of Example l2.
As described hereinbefore in detail$ according to the present invention, a sintered compact having no pore can be efficiently and sure].y obtained since a powdered material to be sintered is completely degassed by the application of heat as well as vacuum to a cup filled with the material and at the same time a solder put on the opening of the Cllp iS melted by said heat so as to air~
tightl.~J seal the Cllp, which is compressible under high pressure at high temperature during hot-pressing while maintaining the air tight seal.
.~,,. : :
,, - ~. ~ - ~ ,
Claims (12)
1. A process of producing a sintered compact comprising:
filling a cup which is compressible under application of heat and pressure with a powdered material to be sintered;
putting on an opening of the cup a covering member consisting of a lid and solder so as to permit ventilation between the interior and exterior of the cup to form a cup assembly;
applying heat as well as vacuum to the cup assembly to degas the powdered material;
melting the solder by the continuation of heat to air-tightly seal the cup with the lid; and hot-pressing the closed cup under high pressure at high temperature to obtain a sintered compact.
filling a cup which is compressible under application of heat and pressure with a powdered material to be sintered;
putting on an opening of the cup a covering member consisting of a lid and solder so as to permit ventilation between the interior and exterior of the cup to form a cup assembly;
applying heat as well as vacuum to the cup assembly to degas the powdered material;
melting the solder by the continuation of heat to air-tightly seal the cup with the lid; and hot-pressing the closed cup under high pressure at high temperature to obtain a sintered compact.
2. A process of producing a sintered compact as claimed in claim 1, wherein said covering member comprises a porous lid closing the cup and a solder put on said porous lid.
3. A process of producing a sintered compact as claimed in claim 1, wherein said covering member comprises a solder member put on the opening of the cup so as to permit ventilation and an air-tight lid put on said solder member.
4. A process of producing a sintered compact as claimed in claim 1, wherein said powdered material comprises a material selected from the group consisting of diamond, cubic boron nitride, mix of diamond with cubic boron nitride, and a mix of binder with each of these materials, said hot-pressing being performed by means of a known super-pressure and high tem-perature apparatus for making a diamond.
5. A process of producing a sintered compact as claimed in claim 1, wherein said lid and cup are made of one material selected from iron and iron base alloys, said solder consisting of one material selected from copper and copper base alloys.
6. A process of producing a sintered compact as claimed in claim 2, wherein said lid and cup are made of one material selected from iron and iron base alloys, said solder consisting of one material selected from copper and copper base alloys.
7. A process of producing a sintered compact as claimed in claim 1, wherein said cup comprises one material selected from nickel and nickel base alloys, said solder consisting of one material selected from copper and copper base alloys.
8. A process of producing a sintered compact as claimed in claim 1, wherein at least a part of said cup comprises a porous material.
9. A process of producing a sintered compact as claimed in claim 1, wherein said powdered material having a particle size less than several microns is cold-pressed to form a green compact under pressures ranging from several ten to several thousand Kg/cm2 before filling in the cup.
10. A process of producing a sintered compact as claimed in claim l, wherein said heat is applied to the cup assembly simultaneously to the application of vacuum.
11. A process of producing a sintered compact as claimed in claim 1, wherein said heat is applied to the cup assembly in the presence of hydrogen gas up to temperatures at which said solder melts and then said vacuum is applied to the cup assembly.
12. A process of producing a sintered compact as claimed in claim 1, wherein said powdered material is mixed with a binder and cold-pressed to form a green compact under a pressure ranging from several ten to several thousand Kg/cm2 before filling the cup .
Applications Claiming Priority (8)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP51-14187 | 1976-02-11 | ||
| JP1418776A JPS5296909A (en) | 1976-02-11 | 1976-02-11 | Production of sintered product |
| JP2148076A JPS52103409A (en) | 1976-02-27 | 1976-02-27 | Manufacture of diamond sintered bodies |
| JP51-21480 | 1976-02-27 | ||
| JP5192776A JPS52134889A (en) | 1976-05-06 | 1976-05-06 | Production of sintered material of diamond |
| JP51-51927 | 1976-05-06 | ||
| JP51-160021 | 1976-12-28 | ||
| JP16002176A JPS5382820A (en) | 1976-12-28 | 1976-12-28 | Process for making sintered body |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1095212A true CA1095212A (en) | 1981-02-10 |
Family
ID=27456152
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA270,596A Expired CA1095212A (en) | 1976-02-11 | 1977-01-27 | Process of producing a sintered compact |
Country Status (5)
| Country | Link |
|---|---|
| CA (1) | CA1095212A (en) |
| DE (1) | DE2705824C3 (en) |
| FR (1) | FR2340918A1 (en) |
| GB (1) | GB1537212A (en) |
| SE (1) | SE421382B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT394329B (en) * | 1987-10-12 | 1992-03-10 | Anh Tuan Dipl Ing Dr Techn Ta | Sintered body and a method for its manufacture |
| CA2462451C (en) * | 2001-11-09 | 2009-10-06 | Sumitomo Electric Industries, Ltd. | Sintered diamond having high thermal conductivity and method for producing the same and heat sink employing it |
| US20160339538A1 (en) * | 2015-05-18 | 2016-11-24 | Toyota Motor Engineering & Manufacturing North America, Inc. | High temperature bonding processes incorporating traces |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE348961C (en) * | 1971-03-15 | 1982-04-19 | Asea Ab | PROCEDURE FOR PREPARING A SINTERED POWDER BODY |
-
1977
- 1977-01-27 CA CA270,596A patent/CA1095212A/en not_active Expired
- 1977-02-08 GB GB521177A patent/GB1537212A/en not_active Expired
- 1977-02-10 SE SE7701518A patent/SE421382B/en not_active IP Right Cessation
- 1977-02-10 FR FR7703747A patent/FR2340918A1/en active Granted
- 1977-02-11 DE DE19772705824 patent/DE2705824C3/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| DE2705824B2 (en) | 1981-06-25 |
| DE2705824C3 (en) | 1982-03-11 |
| DE2705824A1 (en) | 1977-09-01 |
| SE7701518L (en) | 1977-08-12 |
| SE421382B (en) | 1981-12-21 |
| FR2340918B1 (en) | 1982-10-15 |
| FR2340918A1 (en) | 1977-09-09 |
| GB1537212A (en) | 1978-12-29 |
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| MKEX | Expiry |