CA1040385A - Large particle hexagonal boron nitride - Google Patents
Large particle hexagonal boron nitrideInfo
- Publication number
- CA1040385A CA1040385A CA205,299A CA205299A CA1040385A CA 1040385 A CA1040385 A CA 1040385A CA 205299 A CA205299 A CA 205299A CA 1040385 A CA1040385 A CA 1040385A
- Authority
- CA
- Canada
- Prior art keywords
- boron nitride
- nitride
- mixture
- crystals
- microns
- 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
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B21/00—Nitrogen; Compounds thereof
- C01B21/06—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron
- C01B21/064—Binary compounds of nitrogen with metals, with silicon, or with boron, or with carbon, i.e. nitrides; Compounds of nitrogen with more than one metal, silicon or boron with boron
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B29/00—Single crystals or homogeneous polycrystalline material with defined structure characterised by the material or by their shape
- C30B29/10—Inorganic compounds or compositions
- C30B29/38—Nitrides
-
- C—CHEMISTRY; METALLURGY
- C30—CRYSTAL GROWTH
- C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
- C30B9/00—Single-crystal growth from melt solutions using molten solvents
Abstract
ABSTRACT OF THE DISCLOSURE
Soft hexagonal boron nitride crystals of 200-600 microns platelet size are produced from crystals of less than fifty microns particle size by mixing the small crystals with an intermediate metallic nitride such as Li3N, heating the mixture to a temperature between 1100°C and 1550°C for twenty minutes or more, cooling the mixture, and separating off the water soluble material present in the mixture to leave a residue of large crystals of boron nitride. Alternatively, the heating step can be carried out under a pressure of about 40 kilobars.
Soft hexagonal boron nitride crystals of 200-600 microns platelet size are produced from crystals of less than fifty microns particle size by mixing the small crystals with an intermediate metallic nitride such as Li3N, heating the mixture to a temperature between 1100°C and 1550°C for twenty minutes or more, cooling the mixture, and separating off the water soluble material present in the mixture to leave a residue of large crystals of boron nitride. Alternatively, the heating step can be carried out under a pressure of about 40 kilobars.
Description
~040385 08-SD-63 Boron nitride has been made in the form of soft low-density crystals having a hexagonal crystalline con-figuration. It has also been formed into very hard high-density crystals with a cubic crystalline formation having an atomic crystal structure similar to the mineral zincblende or a hexagonal crys~alline configuration similar to the mineral wurtzite. High-density material having a zincblende structure was disclosed and claimed in Wentorf United States patent 2,947,617 dated August 2, 1960. High-density material having a wurtzite structure was disclosed and claimed in Bundy et al. United States patent 3,212,851 dated October 19, 1965.
The present invention is concem ed with the preparation of "
soft low-density crystals having a larger particle ~ize than i was previously available. The soft low-density form of boron nitride will hereafter be referred to as "hexagonal boron nitride".
Most of the processes for preparing hexagonal boron nitride utilize boric anhydride as the boron source material.
This is reacted with various nitrogen-containing compounds such as NH3, CaCN2, or NaCN usually in the presence of an ~` inorganic filler at temperatures varying from 800C to 1700C.
Examples of the preparation of hexagonal boron nitride are . , .
British patent 742,326; U.S. patents 2,808,314 dated October 1, 1957; 2.855,316 dated October 7, 1958; 2,888,325 dated May 26, 1969; 2,839,366 dated June 17, 1958; 2,865,715 dated December 23, 1958 and 2,834,650 dated May 13, 1958; and Russian patent 129,647. The commercially available hexagonal boron nitride produced according to any of these processes has particle sizes ranging up to a maximum of one to two microns.
U.S. patent 3,144,305 dated August 11, 1964 dis-closes a process for recrystallization of hexagonal boron .
nitride by heating boron nitride in an inorganic liquid to a temperature above 1000C in contact with a preformed hexagonal boron nitride seed crystal. This patent reported recrystallized hexagonal boron nitride particles having average maximum dimensions up to forty microns.
Pyrolytic boron nitride is produced from the gaseous reaction:
3 3 lO00-1900C~ BN + 3NH4Cl Pyrolytic boron nitride formed by this process is deposited in well oriented form but with poor crystallinity. U.S. patent 3,578,408 dated May 11, 1971 describes the recrystallization of pyrolytic boron nitride by compression annealing to produce a highly oriented well crystallized material. However, material produced by this process is rather costly in view of the cost of the raw materials used. ln addition, the method requires operating temperatures in the 2250C - 2540C range.
The present invention provides a method for producing hexagonal boron nitride particles larger than 50 microns in size and normally larger than 100-200 microns in size. This is accomplished by mixing soft hexagonal boron nitride particles of less than 50 microns average particle size with an intermediate metallic nitride, the boron nitride com-prising 50 to 85 mol percent of the mixture, heating the mix-ture to a temperature between 1100C and 1550C for a per iod in excess of twenty minutes, cooling the mixture, and separating the boron nitride from the mixture by a process such as the aquaeous solution of water-soluble material and removal thereof as by filtration to leave a residue of , hexagonal boron nitride crystals having an average particle size of lO0 microns or more. The basic process of the in-vention is the reaction of small-particle-sized boron nitride , with an intermediate metallic nitride and the subsequent ;: "
`~ - 2 -, - - . . , , ~ , 11~)4l~)385 recrystallization of larger-sized crystalline hexagonal boron nitride from the mixture at elevated temperatures which are above the melting point of the reaction product. Alkali metal nitrides, alkaline earth metal nitrides, nitrides of tin, lead, and antimony, and mixtures thereof are satisfactory metallic nitrides for use in this invention. A preferred metallic nitride is lithium nitride. Accordingly, the process will be particularly aescribed with reference to lithium nitride.
The process is conveniently carried out at atmospheric pressure. Lithium nitride and boron nitride powders com-prising 50 to 85 mol percent of boron nitride are intimately mixed and placed in containers composed of such materials as molybdenum and graphite for heating. ~eating is carried out in a tubular induction furnace. Where the container is com-~ posed of carbon the graphite serves as a high-frequency field b~' susceptor. Where molybdenum is used as the container material, Y the molybdenum is either partially or wholly surrounded by a " carbon susceptor to provide coupling with the high-frequency field. Inlet and outlet feed-throughs are provided for maintaining a nitrogen gas atmosphere and a thermocouple feed-through is provided for monitoring temperature.
After placing the powder mixture in the furnace, theh furnace is flushed for fifteen minutes with nitrogen gas . .
before heating is started. The mixture is then heated at a rate of about 10-20C per minute by adjusting the power of the radio frequency generator until a temperature between about 1100C and 1550C is reached. Temperatures within this range are maintained for twenty minutes or more and the mixture is then allowed to cool in the flowing nitrogen atmosphere. The sample is then removed from the container and treated with ; boiling water to dissolve all soluble components. The residue :
~ - 3 -,.:
1~40385 08-SD-63 is recrystallized boron nitride which is washed with boiling water and air dried.
A clue to the mechanism of the reaction was provided by using a quartz tube furnace to allow visual observation of the mixture during heat. At temperatures between 100C and 200c the color of the amorphous lithium nitride was observed to change from reddish brown to white. The cause of this color change has not been determined with certainty but it is believed to be due to a phase change in the lithium nitride from the amorphous phase to a crystalline phase. On further heating an exothermic reaction was observed within the temperature range of 550C to 650C. The exothermic nature of the reaction was evident by an increase in the measured heating rate, the heat evolution being high enough to raise the temperature locally and momentarily to some melting temperature in the system. A melted zone was observed to progress momentarily through the sample. It is believed that the action which took place was:
Li3N + BN __~ Li3N2B + ~ H
: ' After momentary melting the material resolidified but as the temperature increased to within therange 800-900C melting was again observed. On continued heating above the melting point, white fumes were observed in the nitrogen gas passing from the furnace. These fumes are believed to result from the incongruent vaporization of lithium nitride from the melt.
Incongruent vaporization of lithium nitride would suggest that the lithium nitride and boron nitride species exist separately in the melt or form only a weakly associated Li3N-BN complex.
Recrystallization was observed for high-temperature holding periods from twenty minutes to four hours and temperatures from 1100C to 1550C. Recrystallization has -1~4V385 08-SD-63 been obtained with starting mixtures having boron nitride compositions varying from 50 to 85 mol percent. sest results have been obtained with starting compositions corresponding to the Li3N BN complex (43 weight percent boron nitride, 57 weight percent lithium nitride). Mixtures containing excess boron nitride show complete recrystallization of the boron nitride up to 80 weight percent boron nitride.
Two possibilities for explaining the recrystallization mechanism appear possible. First, vaporization of lithium nitride from the melt at high temperatures would result in excess boron nitride compared to that required for the postulated Li3N BN complex resulting in precipitation of the ; excess boron nitride to form the recrystallized particles.
, Alternatively, if, as postulated above, lithium nitride and boron nitride species are separated or only : loosely associated within the melt, the liquid can more aptly be thought of as a solution of boron nitride in lithium nitride. A decreasing solubility of boron nitride with in-creasing temperature - sometimes referred to as "retrograde solubility" - which would be consistent with the exothermic nature of the lithium nitride plus boron nitride reaction, would result in precipitation and growth of boron nitride ; particles as the temperature is increased above the melting temperature~ Recrystallization attained under high pressures ~; supports this view since, under these conditions, vaporization is severely repressed.
; The process may be carried out under high pressure conditions without adversely affecting the results. For example, if the mixture is packed into a titanium cell and `~ 30 subjected to pressures of 40 kilobars and temperatures of ~ 1500C for times of from eight minutes to three hours, ;:
, recrystallized material having particle dimensions up to . .
. _ 5 . .
,........ . . ... . . .. . .. . .
1~4~385 08-SD-63 about 200 microns has been observed.
While the invention has been described with reference to certain specific embodiments it is obvious that there may be variations which properly fall within the scope of the invention. Therefore, the invention should be limited in scope only as may be necessitated by the scope of the appended claims.
The present invention is concem ed with the preparation of "
soft low-density crystals having a larger particle ~ize than i was previously available. The soft low-density form of boron nitride will hereafter be referred to as "hexagonal boron nitride".
Most of the processes for preparing hexagonal boron nitride utilize boric anhydride as the boron source material.
This is reacted with various nitrogen-containing compounds such as NH3, CaCN2, or NaCN usually in the presence of an ~` inorganic filler at temperatures varying from 800C to 1700C.
Examples of the preparation of hexagonal boron nitride are . , .
British patent 742,326; U.S. patents 2,808,314 dated October 1, 1957; 2.855,316 dated October 7, 1958; 2,888,325 dated May 26, 1969; 2,839,366 dated June 17, 1958; 2,865,715 dated December 23, 1958 and 2,834,650 dated May 13, 1958; and Russian patent 129,647. The commercially available hexagonal boron nitride produced according to any of these processes has particle sizes ranging up to a maximum of one to two microns.
U.S. patent 3,144,305 dated August 11, 1964 dis-closes a process for recrystallization of hexagonal boron .
nitride by heating boron nitride in an inorganic liquid to a temperature above 1000C in contact with a preformed hexagonal boron nitride seed crystal. This patent reported recrystallized hexagonal boron nitride particles having average maximum dimensions up to forty microns.
Pyrolytic boron nitride is produced from the gaseous reaction:
3 3 lO00-1900C~ BN + 3NH4Cl Pyrolytic boron nitride formed by this process is deposited in well oriented form but with poor crystallinity. U.S. patent 3,578,408 dated May 11, 1971 describes the recrystallization of pyrolytic boron nitride by compression annealing to produce a highly oriented well crystallized material. However, material produced by this process is rather costly in view of the cost of the raw materials used. ln addition, the method requires operating temperatures in the 2250C - 2540C range.
The present invention provides a method for producing hexagonal boron nitride particles larger than 50 microns in size and normally larger than 100-200 microns in size. This is accomplished by mixing soft hexagonal boron nitride particles of less than 50 microns average particle size with an intermediate metallic nitride, the boron nitride com-prising 50 to 85 mol percent of the mixture, heating the mix-ture to a temperature between 1100C and 1550C for a per iod in excess of twenty minutes, cooling the mixture, and separating the boron nitride from the mixture by a process such as the aquaeous solution of water-soluble material and removal thereof as by filtration to leave a residue of , hexagonal boron nitride crystals having an average particle size of lO0 microns or more. The basic process of the in-vention is the reaction of small-particle-sized boron nitride , with an intermediate metallic nitride and the subsequent ;: "
`~ - 2 -, - - . . , , ~ , 11~)4l~)385 recrystallization of larger-sized crystalline hexagonal boron nitride from the mixture at elevated temperatures which are above the melting point of the reaction product. Alkali metal nitrides, alkaline earth metal nitrides, nitrides of tin, lead, and antimony, and mixtures thereof are satisfactory metallic nitrides for use in this invention. A preferred metallic nitride is lithium nitride. Accordingly, the process will be particularly aescribed with reference to lithium nitride.
The process is conveniently carried out at atmospheric pressure. Lithium nitride and boron nitride powders com-prising 50 to 85 mol percent of boron nitride are intimately mixed and placed in containers composed of such materials as molybdenum and graphite for heating. ~eating is carried out in a tubular induction furnace. Where the container is com-~ posed of carbon the graphite serves as a high-frequency field b~' susceptor. Where molybdenum is used as the container material, Y the molybdenum is either partially or wholly surrounded by a " carbon susceptor to provide coupling with the high-frequency field. Inlet and outlet feed-throughs are provided for maintaining a nitrogen gas atmosphere and a thermocouple feed-through is provided for monitoring temperature.
After placing the powder mixture in the furnace, theh furnace is flushed for fifteen minutes with nitrogen gas . .
before heating is started. The mixture is then heated at a rate of about 10-20C per minute by adjusting the power of the radio frequency generator until a temperature between about 1100C and 1550C is reached. Temperatures within this range are maintained for twenty minutes or more and the mixture is then allowed to cool in the flowing nitrogen atmosphere. The sample is then removed from the container and treated with ; boiling water to dissolve all soluble components. The residue :
~ - 3 -,.:
1~40385 08-SD-63 is recrystallized boron nitride which is washed with boiling water and air dried.
A clue to the mechanism of the reaction was provided by using a quartz tube furnace to allow visual observation of the mixture during heat. At temperatures between 100C and 200c the color of the amorphous lithium nitride was observed to change from reddish brown to white. The cause of this color change has not been determined with certainty but it is believed to be due to a phase change in the lithium nitride from the amorphous phase to a crystalline phase. On further heating an exothermic reaction was observed within the temperature range of 550C to 650C. The exothermic nature of the reaction was evident by an increase in the measured heating rate, the heat evolution being high enough to raise the temperature locally and momentarily to some melting temperature in the system. A melted zone was observed to progress momentarily through the sample. It is believed that the action which took place was:
Li3N + BN __~ Li3N2B + ~ H
: ' After momentary melting the material resolidified but as the temperature increased to within therange 800-900C melting was again observed. On continued heating above the melting point, white fumes were observed in the nitrogen gas passing from the furnace. These fumes are believed to result from the incongruent vaporization of lithium nitride from the melt.
Incongruent vaporization of lithium nitride would suggest that the lithium nitride and boron nitride species exist separately in the melt or form only a weakly associated Li3N-BN complex.
Recrystallization was observed for high-temperature holding periods from twenty minutes to four hours and temperatures from 1100C to 1550C. Recrystallization has -1~4V385 08-SD-63 been obtained with starting mixtures having boron nitride compositions varying from 50 to 85 mol percent. sest results have been obtained with starting compositions corresponding to the Li3N BN complex (43 weight percent boron nitride, 57 weight percent lithium nitride). Mixtures containing excess boron nitride show complete recrystallization of the boron nitride up to 80 weight percent boron nitride.
Two possibilities for explaining the recrystallization mechanism appear possible. First, vaporization of lithium nitride from the melt at high temperatures would result in excess boron nitride compared to that required for the postulated Li3N BN complex resulting in precipitation of the ; excess boron nitride to form the recrystallized particles.
, Alternatively, if, as postulated above, lithium nitride and boron nitride species are separated or only : loosely associated within the melt, the liquid can more aptly be thought of as a solution of boron nitride in lithium nitride. A decreasing solubility of boron nitride with in-creasing temperature - sometimes referred to as "retrograde solubility" - which would be consistent with the exothermic nature of the lithium nitride plus boron nitride reaction, would result in precipitation and growth of boron nitride ; particles as the temperature is increased above the melting temperature~ Recrystallization attained under high pressures ~; supports this view since, under these conditions, vaporization is severely repressed.
; The process may be carried out under high pressure conditions without adversely affecting the results. For example, if the mixture is packed into a titanium cell and `~ 30 subjected to pressures of 40 kilobars and temperatures of ~ 1500C for times of from eight minutes to three hours, ;:
, recrystallized material having particle dimensions up to . .
. _ 5 . .
,........ . . ... . . .. . .. . .
1~4~385 08-SD-63 about 200 microns has been observed.
While the invention has been described with reference to certain specific embodiments it is obvious that there may be variations which properly fall within the scope of the invention. Therefore, the invention should be limited in scope only as may be necessitated by the scope of the appended claims.
Claims (10)
1. The method of producing sort hexagonal boron nitride crystals of larger than 50 microns average particle size which comprises:
mixing soft hexagonal boron nitride particles of less than 50 microns average particle size with an intermediate metallic nitride selected from the group consisting of alkali metal nitrides, alkaline earth metal nitrides, nitrides of tin, lead and antimony, and mixtures thereof, the boron nitride com-prising 50 to 85 mol percent of the boron nitride-metallic nitride mixture, heating said mixtures to a temperature between 1100°C
and 1550°C for a period in excess of twenty minutes, cooling said mixture, and separating the boron nitride from the mixture.
mixing soft hexagonal boron nitride particles of less than 50 microns average particle size with an intermediate metallic nitride selected from the group consisting of alkali metal nitrides, alkaline earth metal nitrides, nitrides of tin, lead and antimony, and mixtures thereof, the boron nitride com-prising 50 to 85 mol percent of the boron nitride-metallic nitride mixture, heating said mixtures to a temperature between 1100°C
and 1550°C for a period in excess of twenty minutes, cooling said mixture, and separating the boron nitride from the mixture.
2. The method of claim 1 wherein separation of the boron nitride is accomplished by the aqeous solution and separa-tion of water-soluble material.
3. The method of claim 1 wherein the heating step is carried out under pressures of about forty kilobars, the pressure being maintained until the conclusion of the cooling step.
4. The method of claim 1 wherein the metallic nitride is lithium nitride.
5. The method of claim 4 wherein boron nitride and said lithium nitride are present in equimolar proportions.
6. The method of claim 5 wherein the heating step is carried out under a pressure of at least about 40 kilobars.
7. The method of producing soft hexagonal boron nitride crystals having an average particle size of greater than 50 microns which comprises:
mixing soft hexagonal boron nitride crystals having an average particle size of less than 50 microns with a metallic nitride selected from the group consisting of alkali metal nitrides, alkaline earth metal nitrides, nitrides of tin, lead and antimony and mixtures thereof, said boron nitride comprising 50 to 85 mole percent of the boron nitride-metallic nitride mixture, heating said mixture to a temperature of between about 1100°C and about 1550°C for a suitable period of time, cooling said mixture, and separating the boron nitride from said mixture.
mixing soft hexagonal boron nitride crystals having an average particle size of less than 50 microns with a metallic nitride selected from the group consisting of alkali metal nitrides, alkaline earth metal nitrides, nitrides of tin, lead and antimony and mixtures thereof, said boron nitride comprising 50 to 85 mole percent of the boron nitride-metallic nitride mixture, heating said mixture to a temperature of between about 1100°C and about 1550°C for a suitable period of time, cooling said mixture, and separating the boron nitride from said mixture.
8. The method of claim 7 wherein said metallic nitride is lithium nitride.
9. The method of claim 8 wherein said time is in the range of about 0.3 to about 4 hours.
10. The method of claim 7 or 8 when carried out at an elevated pressure.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US39463573A | 1973-09-06 | 1973-09-06 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1040385A true CA1040385A (en) | 1978-10-17 |
Family
ID=23559782
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA205,299A Expired CA1040385A (en) | 1973-09-06 | 1974-07-22 | Large particle hexagonal boron nitride |
Country Status (13)
| Country | Link |
|---|---|
| JP (1) | JPS558925B2 (en) |
| AT (1) | AT362746B (en) |
| BE (1) | BE818939A (en) |
| CA (1) | CA1040385A (en) |
| CH (1) | CH605404A5 (en) |
| DE (1) | DE2441298C3 (en) |
| FR (1) | FR2243151B1 (en) |
| GB (1) | GB1481026A (en) |
| IE (1) | IE39637B1 (en) |
| IT (1) | IT1020281B (en) |
| NO (1) | NO137588C (en) |
| SE (1) | SE394415B (en) |
| ZA (1) | ZA744736B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58126464U (en) * | 1982-02-18 | 1983-08-27 | コニカ株式会社 | developing device |
| JPS58133156U (en) * | 1982-03-03 | 1983-09-08 | コニカ株式会社 | developing device |
| FR2796657B1 (en) * | 1999-07-20 | 2001-10-26 | Thomson Csf | PROCESS FOR THE SYNTHESIS OF SOLID MONOCRYSTALLINE MATERIALS IN NITRIDES OF ELEMENTS OF COLUMN III OF THE TABLE OF THE PERIODIC CLASSIFICATION |
-
1974
- 1974-07-22 CA CA205,299A patent/CA1040385A/en not_active Expired
- 1974-07-23 IE IE1563/74A patent/IE39637B1/en unknown
- 1974-07-24 ZA ZA00744736A patent/ZA744736B/en unknown
- 1974-07-29 GB GB33346/74A patent/GB1481026A/en not_active Expired
- 1974-08-16 BE BE147688A patent/BE818939A/en not_active IP Right Cessation
- 1974-08-29 DE DE2441298A patent/DE2441298C3/en not_active Expired
- 1974-08-29 IT IT26719/74A patent/IT1020281B/en active
- 1974-09-03 AT AT0710174A patent/AT362746B/en not_active IP Right Cessation
- 1974-09-03 FR FR7429930A patent/FR2243151B1/fr not_active Expired
- 1974-09-04 CH CH1199174A patent/CH605404A5/xx not_active IP Right Cessation
- 1974-09-05 JP JP10144874A patent/JPS558925B2/ja not_active Expired
- 1974-09-05 NO NO743192A patent/NO137588C/en unknown
- 1974-09-05 SE SE7302002A patent/SE394415B/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| JPS558925B2 (en) | 1980-03-06 |
| CH605404A5 (en) | 1978-09-29 |
| DE2441298B2 (en) | 1981-03-12 |
| SE394415B (en) | 1977-06-27 |
| IE39637L (en) | 1975-03-06 |
| DE2441298C3 (en) | 1982-01-28 |
| IE39637B1 (en) | 1978-11-22 |
| FR2243151B1 (en) | 1978-07-13 |
| IT1020281B (en) | 1977-12-20 |
| NO137588B (en) | 1977-12-12 |
| NO743192L (en) | 1975-04-01 |
| NO137588C (en) | 1978-03-21 |
| AT362746B (en) | 1981-06-10 |
| JPS5076000A (en) | 1975-06-21 |
| DE2441298A1 (en) | 1975-03-13 |
| BE818939A (en) | 1974-12-16 |
| GB1481026A (en) | 1977-07-27 |
| SE7411253L (en) | 1975-03-07 |
| ATA710174A (en) | 1980-11-15 |
| ZA744736B (en) | 1975-11-26 |
| AU7158474A (en) | 1976-01-29 |
| FR2243151A1 (en) | 1975-04-04 |
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