GB2079869A - Solid-lubricated Bearing and Method of Fabricating Same - Google Patents
Solid-lubricated Bearing and Method of Fabricating Same Download PDFInfo
- Publication number
- GB2079869A GB2079869A GB8117850A GB8117850A GB2079869A GB 2079869 A GB2079869 A GB 2079869A GB 8117850 A GB8117850 A GB 8117850A GB 8117850 A GB8117850 A GB 8117850A GB 2079869 A GB2079869 A GB 2079869A
- Authority
- GB
- United Kingdom
- Prior art keywords
- bearing
- solid
- lubricated bearing
- ceramic
- lubricated
- 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.)
- Granted
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
- B22F3/24—After-treatment of workpieces or articles
-
- 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
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
- C04B41/50—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials
-
- 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
- C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
- C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
- C04B41/81—Coating or impregnation
- C04B41/85—Coating or impregnation with inorganic materials
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
- F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
- F16C33/02—Parts of sliding-contact bearings
- F16C33/04—Brasses; Bushes; Linings
- F16C33/043—Sliding surface consisting mainly of ceramics, cermets or hard carbon, e.g. diamond like carbon [DLC]
-
- G—PHYSICS
- G04—HOROLOGY
- G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
- G04B31/00—Bearings; Point suspensions or counter-point suspensions; Pivot bearings; Single parts therefor
- G04B31/06—Manufacture or mounting processes
Abstract
A solid-lubricated bearing comprising a ceramic and at least one of metals selected from the group consisting of Mo, W, V, Nb, Ta, Ti, Hf, Re, Th, U, Te, oxides thereof and Zr the coefficient of friction whereof is lowered by conversion to one of a sulfide and a selenide, the surface of said bearing having the sulfide or selenide phase of said metal. <IMAGE>
Description
SPECIFICATION
Solid-Lubricated Bearing and Method of
Fabricating Same
Background of the Invention
This invention relates to a solid-lubricated ceramic bearing for timepieces and precision instruments and to a method of fabricating the same, the surface of the bearing having a metal sulfide or selenide phase.
It is conventional practice to employ a hard stone or a metal as a material for bearings used in timepieces and precision instruments, and oiling must be effected between the bearing and shaft which it supports. Oiling reduces the coefficient of friction between the bearing and shaft and prevents the wear of moving parts. A shortcoming encountered in the prior art is that bearing must be disassembled when periodically replenishing the volatile oil, when the oil experiences a chemical change in its properties, and when there is a decrease in the performance of the oil because of aging. A conventional timepiece bearing that requires oiling is shown in the crosssectional view of Fig. 1, in which numeral 11 denotes a ruby bearing for a timepiece, 1 2 a gear shaft, and 13 a recess that serves as an oil reservoir.
An oilless bearing, which consists of a synthetic resin or of a composite material including a synthetic resin, graphite, MOS2 or the like, is low in material strength and may become distorted when called upon to transmit a large torque. Such distortion degrades transmission effectiveness by a wide margin. In addition, since coefficient of friction increases in hightemperature environments, the bearing of the above type can no longer fully perform the intended function. Thus, the conventional bearings of the type described have certain shortcomings.
Summary of the Invention
According to the present invention, there is provided a solid-lubricated bearing comprising a ceramic and at least one of metals selected from the group consisting of Mo, W, V, Nb, Ta, Ti, Hf,
Re, Th, U, Te and oxides thereof, the surface of said bearing having a solid lubricating phase of said metal.
Brief Description of the Drawings
Fig. 1 is a cross-sectional view of a conventional bearing;
Fig. 2 is a flow chart illustrating an embodiment of a first method of the present invention;
Fig. 3 is a cross-sectional view of a bearing embodying the present invention;
Fig. 4 is a flow chart illustrating an embodiment of a second method of the present invention;
Fig. 5 is a cross-sectional view of a second preferred embodiment a bearing according to the present invention; and
Fig. 6 is a cross-sectional view of a third preferred embodiment of the present invention.
Detailed Description of Preferred Embodiments
Fig. 2 illustrates the steps for fabricating a solid-lubricated bearing of an aluminum ceramictungsten disulfide type according to a first preferred embodiment of the present invention. A mixture of tungsten powder and a raw material of an aluminum ceramic (a mixture which contains Awl203, MgO, SiO2 and CaO) is prepared by weighing out the materials in such a manner that the proportion of tungsten is from 1 to 40% in terms of volume ratio. PVA (polyvinyl alcohol) or
PEG (polyethylene glycol) is then added to the tungsten and raw material mixture as a binder for press molding. The resulting composition is subjected to further mixing and to pulverization in a ball mill to form a mixture having a muddy consistency.To convert this into granules for powder molding, the mixture is subjected to a spray drier to induce granulation (practicle size of from 80 to 1 00y9). Next, a powder molding step is applied in which a molded article of a prescribed shape is obtained by subjecting the granules to a molding pressure of from 2 to 6 tons per square centemeter using an air press or hydraulic press. To remove the molding binder, the molded article is subjected to primary calcination for two hours at a temperature of 6000C in a moist hydrogen atmosphere having a dew point of from + 10 to +400C. This is followed by secondary calcination for one hour at a temperature of 1 60000 in a hydrogen atmosphere having a dew point of not higher than -200C, or in a vacuum of not greater than 10-3 torr.The result is composite sintered body of aluminum ceramic and tungsten. Grinding is then applied to shape the sintered body into the prescribed configuration. The process steps from the weighing of the starting materials to grinding, denoted by numeral 14 in Fig. 2, are for the purpose of preparing a ceramic bearing containing a metal whose coefficient of friction is capable of being lowered when it is converted into a sulfide by the following step. Specifically, in the sulfurization step 15, the ceramic bearing is treated for two hours at a temperature of from 600 to 7000C in a mixed atmosphere of H2S, H2 and NH3, thereby to provide the bearing surface with a tungsten sulfide phase which extends down to a depth of approximately 50y. Table I shows the composition of the aluminum ceramictungsten starting material.
Aluminum ceramic Awl203 100 parts MgO 0.5 CaO 1.5 " 95.5 to 24.8 wt% SiO 3.5 it 4.5 to 75.2 .
Table I
Fig. 3 shows the cross-section of the solidlubricated bearing which is obtained according to the illustrated embodiment. Numeral 1 6 denotes a cylindrical solid-lubricated bearing provided with a circular hole at its center. The bearing comprises a ceramic 1 6c and a sulfide phase 1 6b which serves as lubricating means. The bearing has an outer diameter of 2.20(++o 006) millimeters and a surface roughness of 1.5-S. The circular hole 1 6a has a diameter of 1 46(++o 006) millimeters and a surface roughness of 0.1-S.
The thickness of the bearing is 0.6 millimeter, and the thickness of the layer having the tungsten disulfide is 50,u. The shaft 1 7 is of the well-known type consisting of hardened steel obtained by heat-treating SK4-F to Hv 720. Its surface roughness is 0.1-S. The diameter of the shaft is 1 940(-o olo2) millimeters.
It is thus possible to form a composite with an aluminum ceramic. The metal whose coefficient of friction has been reduced to a low value by the sulfurization treatment of the composite metal is tungsten in the illustrated embodiment but other metals which can be employed are, for example,
V, Nb, Ta, Ti, Zr, Re, Th, U and Te. Any of these metals can be selected to provide a low coefficient of friction. Furthermore, the ceramic forming the composite with the selected metal is not limited to an aluminum ceramic. A glass capable of withstanding the sulfurization treatment can also be used to good effect to provide the solid-lubrication bearing'of the present invention. The method of obtaining the bearing of the prescribed shape is not limited to the powder molding method, for the bearing can be formed by press-punching it from a green sheet obtained by means of a doctor blade method.
Illustrated in Table II are coefficients of friction based upon measurements using a T-type pendulum friction tester.
Specimen Coefficient of friction MoS2 0.13 WS2 0.14 VS2 0.30 NbS2 0.10 TaS2 0.06 TiS2 0.30 ZrS2 0.33 Table II
Fig. 4 illustrates the steps for fabricating a solid-lubricated bearing of an aluminum ceramic
WSe2 type according to a second embodiment of the present invention. A mixture of tungsten powder and a raw material of an aluminum ceramic (a mixture which contains Awl203, MgO,
SO2, and a CaO) in prepared by weighing out the materials in such a manner that the proportion of tungsten is from 1 to 40% in terms of volume ratio. PVA (polyvinyl alcohol) is then added to the tungsten and raw material mixture as a binder for press molding.The resulting composition is subjected to further mixing and to pulverization in a ball mill to form a mixture having a muddy consistency. To convert this into granules for powder molding, the mixture is subjected to a spray drier to induce granulation (particle size of from 80 to 1 00jut). Next, a powder molding step is applied wherein a molded article of a prescribed shape is obtained by subjecting the granules to a molding pressure of from 2 to 6 tons per square centimeter using a hydraulic press. To remove the molding binder, the molded article is subjected to primary calcination for two hours at a temperature of 6000C in a moist atmosphere having a dew point of from +10 to +400C.This is followed by secondary calcination for one hour at a temperature of 1 6000C in a hydrogen atmosphere having a dew point of not higher than -200C, or in a vacuum of not greater than 10-3 torn The result is a composite sintered body of an aluminum ceramic and tungsten. Grinding is then applied to shape the sintered body into the prescribed configuration. The process steps from the weighing of the starting materials to grinding, denoted by numeral 24 in Fig. 4, are for the purpose of preparing a ceramic bearing containing a metal whose coefficient of friction is capable of being lowered when it is converted into a selenide by the following step.Specifically, in the selenization treatment step 25, the ceramic bearing is treated for two hours at a temperature of from 600 to 7000C in a mixed atmosphere of
SeH2, H2 and NH3, thereby to provide the bearing surface with a WSe2 phase which extends down to a depth of 50y. Table III shows the composition of the aluminum ceramictungsten starting material.
Aluminium ceramic Awl203 100 parts MgO 0.5 CaO 1.5 ,, 95-5 to 24.8 wt% SiO 3.5 W 4.5 to 76.2 wt% Table Ill
Fig. 5 shows the cross-section of the solidlubricated bearing which is obtained according to the illustrated second embodiment. Numeral 26 denotes a cylindrical solid-lubricated bearing provided with a circular hole at its center. The r bearing comprises a ceramic 26c and a selenide plase 26b. The bearing has an outer diameter of 2.2(+o- 6) millimeters and a surface roughness of 1.5 - S. The circular hole 26a has a diameter of 1.4(+%0.oo6)millimeters and a surface roughness of 0.1 - S. The thickness of the bearing is 0.6 millimeter, and the thickness of the layer having the tungsten selenide is approximately 50 microns. The shaft 27 is of the well-known type consisting of hardened steel obtained by heattreating SK4-F to Hv 720. Its surface roughness is 0.1 - S. The diameter of the shaft is 1 '4Q(-0 1 2) millimeters.
It is thus possible to from a composite with an aluminum ceramic. The metal whose coefficient of friction has been reduced to a low value by the selenization treatment of the composite metal is tungsten (W) in the illustrated second embodiment, but other metals which can be employed are, for example, V, Nb, Ta, Ti, Zr, Re,
Th, U and Te. Any of these metals can be selected to fabricate an excellent oilless bearing.
The ceramic forming the composite with the selected metal is not limited to an aluminum ceramic. A glass capable of withstanding the selenization treatment can also be used to good effect to provide the solid-lubricated bearing of the present invention. The method of obtaining the bearing of the prescribed shape is not limited to the powder molding method, for the bearing can be formed by press-punching it from a green sheet obtained by means of a doctor blade method. Illustrated in Table IV are coefficients of friction based upon measurements using a pendulum friction tester.
Specimen I Specimen Coefficient offriction MoSe2 0.13 WSe2 0.10 VSe2 0.22 NbSe2 0.08 Task, 0.06 TiSe2 0.15 ZrSe 0.13 2 Table IV
Described next will be a method of fabricating a solid-lubricated bearing of an aluminum ceramicmolybdenum disulfide type according to an embodiment of the present invention. First, there is prepared a mixture of an aluminum ceramic raw material and MoO3 powder (in which the proportion of MoO3 is from 1 to 40% in terms of volume ratio). The resulting mixture, to which a molding binder has been added, is then subjected to further mixing and to pulverization in a ball mill to form a mixture having a muddy consistency.To convert this into granules for powder molding, the mixture is subjected to a spray drier to induce granulation (particle size of from 20 to 1 00y Next, a molded article is obtained by compacting the granulated powder using a mold of a prescribed shape. To remove the molding binder, the molded article is subjected to primary calcination for about two hours at a temperature of about 600"C in a moist hydrogen atmosphere having a dew point of from + 10 to +400C. This is followed by secondary calcination for about one hour at a temperature of about 1 600cm in a hydrogen atmosphere having a dew point ofnot higher than 200 C, or in a vacuum of not greater than 10-3 torr. The result is a composite sintered body of an aluminum ceramic and MoO3.Grinding is then applied to shape the sintered body into the prescribed configuration. The resulting article is then subjected to a sulfurization treatment for about two hours at a temperature of about 5000C in a nitrogen-based hydrogen sulfide gas, thereby to form a solid lubricant phase of MoS2 on its surface.
Fig. 6 shows the cross-section of the solidlubricated bearing which is formed in the manner described above. Numeral 31 denotes a cylindrical solid-lubricated bearing provided with a circular hole 31 a for receiving a shaft. The molybdenum disulfide is indicated at numeral 31 b. The bearing has an outer diameter of 2.2 (tolerance $OoOO6) millimeters and a surface roughness of 1.5 - S. The circular hole 1 a has a diameter of 1 49(+o . 6) millimeters and a surface roughness of 0.1 - S. The thickness of the bearing is 0.6 millimeter. Numeral 32 denotes the rotary shaft of a well-known gear, the shaft consisting of hardened steel obtained by heattreating SK4-F to a hardness of Hv 720. Its surface roughness is 0.1 - S. The diameter of the shaft 32 is 1.45 (z00:000126) millimeters. A pendulum friction tester was used under the above conditions to measure the coefficient of friction. It was found that the coefficient of friction is 0.13, which is equivalent to that obtained by lubricating a bearing with oil.
Claims (11)
1. A solid-lubricated bearing comprising a ceramic and at least one of metals selected from the group consisting of Mo, W, V, Nb, Ta, Ti, Hf,
Re, Th, U, Te and oxides thereof, the surface of said bearing having a solid lubricating phase of said metal.
2. A solid-lubricated bearing according to claim 1, in which the bearing comprises flat surfaces and a cylindrical surface.
3. A solid-lubricated bearing according to claim 1 or 2, in which said solid lubricating phase is a sulfide of said metal.
4. A solid-lubricated bearing according to claim 1 or 2, in which said solid lubricating phase is a selenide of said metal.
5. A solid-lubricated bearing according to claim
1, 2 or 3, in which said oxides are MoO3 and WO3.
6. A method of fabricating a solid-lubricated bearing comprising the steps of preparing a bearing comprising a ceramic which contains at least one of metals selected from the group consisting of Mo, W, V, Nb, Ta, Ti, Hf, Re, Th, U, Te and oxides thereof, and forming a solid lubricating phase of the surface of said bearing.
7. A method of fabricating a solid-lubricated bearing according to claim 6, in which said bearing is subjected to sulfurization treatment.
8. A method of fabricating a solid-iubricated bearing according to claim 6, in which said bearing is subjected selenization treatment.
9. A method of fabricating a solid-lubricated bearing according to claim 6, 7 or 8, in which said
oxides are MoO2 and WO2.
1 0. A solid-lubricated bearing substantially as shown and described with reference to Figs. 3, 5 and 6 of the drawings.
11. A solid-lubricated bearing fabricated by a method substantially as shown and described with reference to Figs. 2 and 4 of the drawings.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP7802580A JPS574510A (en) | 1980-06-10 | 1980-06-10 | Solid lubricating bearing and its manufacture |
| JP7992280A JPS576128A (en) | 1980-06-13 | 1980-06-13 | Solid lubricating bearing and its manufacturing method |
| JP7098181A JPS57188474A (en) | 1981-05-12 | 1981-05-12 | Manufacture of solid lubricant bearing |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2079869A true GB2079869A (en) | 1982-01-27 |
| GB2079869B GB2079869B (en) | 1985-05-15 |
Family
ID=27300500
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8117850A Expired GB2079869B (en) | 1980-06-10 | 1981-06-10 | Solid-lubricated bearing and method of fabricating same |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2079869B (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0248480A1 (en) * | 1986-06-02 | 1987-12-09 | Koninklijke Philips Electronics N.V. | X-ray tube having a rotary anode |
| EP0252728A2 (en) * | 1986-07-11 | 1988-01-13 | Ngk Insulators, Ltd. | Metallic slide members to be used with ceramic slide members and sliding assemblies using the same |
| US4871266A (en) * | 1987-06-24 | 1989-10-03 | Ngk Insulators, Ltd. | Slide assemblies |
| US4983468A (en) * | 1986-07-11 | 1991-01-08 | Ngk Insulators Ltd. | Metallic slide members to be used with ceramic slide members and sliding assemblies using the same |
-
1981
- 1981-06-10 GB GB8117850A patent/GB2079869B/en not_active Expired
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0248480A1 (en) * | 1986-06-02 | 1987-12-09 | Koninklijke Philips Electronics N.V. | X-ray tube having a rotary anode |
| EP0252728A2 (en) * | 1986-07-11 | 1988-01-13 | Ngk Insulators, Ltd. | Metallic slide members to be used with ceramic slide members and sliding assemblies using the same |
| EP0252728A3 (en) * | 1986-07-11 | 1989-03-15 | Ngk Insulators, Ltd. | Metallic slide members to be used with ceramic slide members and sliding assemblies using the same |
| US4983468A (en) * | 1986-07-11 | 1991-01-08 | Ngk Insulators Ltd. | Metallic slide members to be used with ceramic slide members and sliding assemblies using the same |
| US4871266A (en) * | 1987-06-24 | 1989-10-03 | Ngk Insulators, Ltd. | Slide assemblies |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2079869B (en) | 1985-05-15 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19950610 |