JP2006038029A - Ceramic fiber reinforced ceramic sliding part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sliding part excellent in all characteristic to be required for the sliding part by maintaining slidability, abrasion resistance, hardness and corrosion resistance as the original characteristic of ceramics, and improving flexibility. <P>SOLUTION: A bearing sleeve 1 as a cylindrical sliding part is formed from a ceramic base composite material. The ceramic base composite material has ceramic reinforcing fibers 2 and 3 and a ceramic base material 4. The first ceramic reinforcing fibers 2 are extended in the axial direction, and the second ceramic reinforcing fibers 3 are extended in the radial direction. The first and the second ceramic reinforcing fibers 2 and 3 cross each other. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a ceramic fiber reinforced ceramic sliding part used as a bearing sleeve, a bearing, a mechanical seal or the like.

  Cemented carbides and ceramics are widely used as materials used for sliding parts such as pump bearings.

  Cemented carbide generally has good slidability and wear resistance, but it is a brittle material and has low toughness, so its reliability is not sufficient. In the WC-Co (tungsten carbide-cobalt) cemented carbide, Co as a binder is selectively corroded in a corrosive environment such as in the sea. WC-Ni (tungsten carbide-nickel) cemented carbide has been developed as a countermeasure against selective corrosion, but when this WC-Ni cemented carbide is used as a sliding member, metal parts used in combination (For example, a bearing when a bearing sleeve is a WC-Ni type cemented carbide) and potentiometric corrosion. Furthermore, although TiC (titanium carbide) -based cemented carbide shows excellent corrosion resistance, it has low hardness and inferior wear resistance.

  A sliding component made of ceramics is described in Patent Document 1, for example. However, ceramics have good slidability, wear resistance, and corrosion resistance, but they are brittle materials and have low toughness similar to cemented carbide, so their reliability is not sufficient.

  As described above, all of the properties required for sliding parts, that is, sliding properties, wear resistance, toughness, hardness, and corrosion resistance, have been conventionally selected when either cemented carbide or ceramics is selected. Could not be met at a high level.

JP-A-5-155665

  The present invention significantly improves toughness while maintaining the slidability, wear resistance, hardness, and corrosion resistance inherent in ceramics, and is a characteristic required for sliding parts, that is, slidability, It is an object of the present invention to provide a sliding component that is excellent in wear resistance, toughness, hardness, and corrosion resistance.

  The present invention provides a ceramic fiber reinforced ceramic sliding part characterized in that at least the sliding part is made of a ceramic matrix composite material having a ceramic reinforced fiber and a ceramic base material.

  By combining the ceramic base material and the ceramic reinforcing fiber, the toughness can be greatly improved while maintaining the slidability, wear resistance, hardness, and corrosion resistance inherent in ceramics. Therefore, all the properties generally required for sliding parts are good, ie sliding properties, wear resistance, toughness, hardness and corrosion resistance.

The ceramic base material is any ceramic of SiC (silicon carbide or silicon carbide), Si ₃ N ₄ (silicon nitride), and Al ₂ O ₃ (alumina) that can be used as so-called engineering ceramics. Also good. Further, the ceramic reinforcing fiber may be any one of SiC, Si ₃ N ₄ and Al ₂ O ₃ ceramic fibers.

  As a method for manufacturing a sliding component made of a ceramic matrix composite material, any one of a gas phase process, a liquid phase process, and a solid phase process is adopted according to the type of ceramic selected as the ceramic reinforcing fiber and the ceramic base material. be able to. Examples of the gas phase process include a chemical vapor infiltration method (CVI method: Chemical Vapor Infiltration), a reactive sintering method (RS method: Reaction Sintering), and a directed metal oxidation method (DIMOX method: Directed metal oxidation). Examples of the liquid phase process include a polymer impregnation / pyrolysis method (PIP method: Polymer impregnation and pyrolysis), a sol-gel method, a melt infiltration method (MI method: metal infiltration), and a molten glass infiltration method. Further, examples of the solid phase process include an atmospheric sintering method, a pressure sintering method (hot press, HIP: Hot Isostatic Press), and a self-combustion sintering method (SHS method: Self Propagating High Temperature Synthesis).

  The entire sliding component may be a ceramic matrix composite material, or only the sliding portion of the sliding component, that is, the portion including the sliding surface may be a ceramic matrix composite material.

  For example, the sliding component has a cylindrical shape, and the ceramic reinforcing fiber includes a plurality of first ceramic reinforcing fibers extending in the axial direction and a plurality of second ceramic reinforcing fibers extending in the circumferential direction. One ceramic reinforcing fiber and the second ceramic reinforcing fiber cross each other.

  The present invention can be applied to various sliding parts such as bearing sleeves including those for underwater bearings, bearings including underwater bearings, and mechanical seals.

  Since the ceramic fiber reinforced ceramic sliding part of the present invention maintains the slidability, wear resistance, hardness, and corrosion resistance inherent in ceramics, the toughness is greatly improved. All of the properties generally required for slidability, wear resistance, toughness, hardness, and corrosion resistance are excellent.

  Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings. 1 and 2 show a bearing sleeve 1 which is a sliding component according to the present invention, and FIGS. 3 and 4 show a vertical shaft pump 11 provided with the bearing sleeve 1.

  Referring to FIG. 1, the bearing sleeve 1 has a cylindrical shape and is made of a ceramic matrix composite material having ceramic reinforcing fibers 2 and 3 and a ceramic base material 4. A plurality of preforms 5 of SiC-based ceramic reinforcing fibers 2, 3 are present in a SiC (silicon carbide) -based ceramic base material 4. Of the ceramic reinforcing fibers 2 and 3 constituting each preform 5, one ceramic reinforcing fiber 2 is arranged and oriented in the axial direction of the cylindrical bearing sleeve 1, and the other ceramic fiber 3 is arranged and oriented in the circumferential direction. Oriented. The ceramic reinforcing fiber 2 in the axial direction and the ceramic reinforcing fiber 3 in the circumferential direction are orthogonal to each other.

  As shown in FIG. 2, each ceramic reinforcing fiber 2, 3 is a bundle of a large number of strands 6 (not particularly limited, for example, about 200 to 1500) made of SiC ceramics. Further, in one preform 5, the ceramic reinforcing fibers 2 in the axial direction and the ceramic reinforcing fibers 3 in the circumferential direction are arranged so as to move up and down alternately. The preform 5 may be a woven fabric woven by plain weaving or the like, or may be a tubular body knitted by knit knitting or blade knitting.

  The bearing sleeve 1 has, for example, an outer diameter D of about 50 to 300 mm, a length L of about 0.4 to 1.0 times the outer diameter D, and a thickness t of about 2 to 10 mm. When the thickness t is in this range, the number of laminated preforms 5 is about several to several tens. The fiber content of the bearing sleeve 1 is, for example, about 20 to 70 wt%.

  Since the ceramic reinforcing fibers 2 and 3 and the ceramic base material 4 are both SiC ceramics, a chemical vapor infiltration (CVI method) can be adopted as a method of manufacturing the bearing sleeve 1. When the bearing sleeve 1 is manufactured by the CVI method, the preform 5 is placed under a predetermined temperature gradient or pressure gradient, and the raw material gas is thermally decomposed to deposit Si-based ceramics that become the ceramic base material 4.

  Referring to FIG. 3, the vertical shaft pump 11 includes a pump casing 12 that is disposed in the water tank 11 and extends in the vertical direction. The pump casing 12 includes a suction bell mouth 12a at the lower end, and a discharge elbow 12b connected to a discharge side pipe (not shown) on the upper end side. A main shaft 13 extends vertically in the pump casing 12. An impeller 14 is fixed to the lower end of the main shaft 13. The upper end of the main shaft 13 protrudes from the inside of the pump casing 12 through a sealing device 15 and is connected to a drive mechanism including a motor, a speed reduction mechanism, and the like through a joint 16.

  The vicinity of the impeller 14 of the main shaft 13 (lower side) and the upper side (upper side) of the center are rotatably supported by bearings 18 and 19 made of SiC, respectively, and are respectively supported by portions supported by the bearings 18 and 19 of the main shaft 13. The bearing sleeve 1 of this embodiment is mounted. Referring to FIG. 4, the lower bearing 18 is fixed to a bearing casing 21 via an elastic body 20, and the bearing casing 21 is fixed to the pump casing 12 by a rib 22. The bearing sleeve 1 is fixed to the main shaft 13 via a mounting member 23. The same applies to the mounting structure of the upper bearing 19 and the corresponding bearing sleeve 1.

  As will be described in detail later, the bearing sleeve 1 is formed by combining the ceramic base material 4 and the ceramic reinforcing fibers 2 and 3 and orienting and arranging the ceramic reinforcing fibers 2 and 3 in the axial direction and the circumferential direction. While maintaining the inherent slidability, wear resistance, hardness, and corrosion resistance, the toughness is greatly improved. Therefore, the vertical shaft pump 11 of FIG. 3 provided with this bearing sleeve 1 has greatly improved reliability. Specifically, the possibility that the bearing sleeve 1 is damaged due to brittleness is greatly reduced.

  An experiment was conducted to measure the characteristic value of the bearing sleeve 1 of the embodiment. Specifically, the coefficient of friction (slidability), wear resistance, and toughness (fracture brittleness value) were measured. The bearing sleeve 1 used in the experiment had an outer diameter D of 100 mm, a length L of 62 mm, and a thickness t of 3 mm. Further, a bearing made of SiC was used for measuring the friction coefficient and the wear resistance. In the following table, “Experimental example” indicates a bearing sleeve (a bearing sleeve made of ceramic fiber reinforced ceramics) according to an embodiment of the present invention, and “Comparative example” is a bearing sleeve made of a WC cemented carbide. It shows that. In the table, “SiC / SiC” indicates ceramic fiber reinforced ceramics.

  Table 1 shows the measurement results of the dynamic friction coefficient (slidability).

動摩擦係数

Dynamic friction coefficient

  As shown in Table 1, the dynamic friction coefficient in water is 0.02 in both the experimental example and the comparative example, but the dynamic friction coefficient in the air is 0.31 in the comparative example, while the experimental example In this case, it is reduced to 0.28. Therefore, it can be confirmed that the bearing sleeve of the embodiment is excellent in slidability.

  Table 2 shows the measurement results of wear resistance. Abrasion resistance was measured by the amount of wear when the shaft was continuously rotated in the slurry for a certain time. The test conditions were a bearing surface pressure of 0.5 Mpa, a bearing peripheral speed of 5 m / sec, a slurry concentration (silica sand) of 2000 ppm, and a rotation time of 1000 hours.

  As shown in Table 2, the wear amount of the bearing sleeve is 25 μm in the comparative example, but is greatly reduced to 16 μm in the experimental example. Further, the wear amount of the bearing is 12 μm in the comparative example, but is slightly reduced to 11 μm in the experimental example. Therefore, it can be confirmed that the bearing sleeve of the embodiment is excellent in wear resistance.

Table 3 shows the toughness measurement results. The fracture toughness value was measured by the K _IC measurement method (ASTM E399).

As shown in Table 3, the fracture toughness value is 12 MPa / m ^1/2 in the comparative example, while it is greatly increased in the experimental example to 20 MPa / m ^1/2 . Therefore, it can be confirmed that the bearing sleeve of the embodiment is excellent in toughness.

  Next, the hardness will be described. The hardness (Vickers hardness) of WC, TiC, and SiC is as shown in Table 4.

  As shown in Table 4, the ceramic reinforcing fiber of the bearing sleeve of the embodiment and SiC that is the ceramic base material have higher hardness than WC and TiC.

  Furthermore, with regard to corrosion resistance, the bearing sleeve of the embodiment made of ceramic fiber reinforced ceramics is also subject to selective corrosion that is a problem with WC-Co cemented carbides and potential difference corrosion that is a problem with WC-Ni cemented carbides. It does not occur and has high corrosion resistance.

  As described above, the ceramic fiber reinforced ceramic of the bearing sleeve according to the embodiment has greatly improved toughness while maintaining the slidability, wear resistance, hardness, and corrosion resistance inherent in the ceramic. .

  The present invention is not limited to the above embodiment, and various modifications can be made. For example, the present invention can be applied to other various sliding parts such as a bearing including an underwater bearing and a mechanical seal.

The ceramic base material may be Si ₃ N ₄ -based or Al ₂ O ₃ -based ceramics, and the ceramic reinforcing fiber may be Si ₃ N ₄ -based or Al ₂ O ₃ -based ceramic fibers.

  The manufacturing method of the sliding component is not limited to the CVI method. Depending on the type of ceramics selected as ceramic reinforcing fiber and ceramic base material, other gas phase processes such as reaction sintering method (RS method: Reaction Sintering), directional metal oxidation method (DIMOX method), Liquid phase processes such as polymer impregnation and pyrolysis (PIP method), sol-gel method, melt infiltration method (MI method: metal infiltration), molten glass infiltration method, and atmospheric pressure sintering method, pressure firing A solid phase process such as a kneading method (hot press, HIP: Hot Isostatic Press) or a self-combustion sintering method (SHS method: Self Propagating High Temperature Synthesis) can be employed.

  In the above embodiment, the entire bearing sleeve, which is a sliding component, is made of a ceramic matrix composite material having ceramic reinforcing fibers and a ceramic base material. However, the sliding portion of the sliding component, that is, the portion including the sliding surface Only a ceramic matrix composite material may be used.

  Furthermore, in the said embodiment, although the ceramic reinforcing fiber 2 of the vertical direction and the ceramic reinforcing fiber 3 of the horizontal direction are mutually orthogonal, the crossing angle of these ceramic reinforcing fibers 2 and 3 is not limited to 90 degree | times.

The schematic perspective view which shows the bearing sleeve which concerns on embodiment of this invention. Partial enlarged view of the preform. Sectional drawing which shows a vertical shaft pump provided with the bearing sleeve which concerns on embodiment of this invention. FIG. 4 is an enlarged view of a part IV in FIG. 3.

Explanation of symbols

1 Bearing sleeve (sliding part)
DESCRIPTION OF SYMBOLS 2,3 Ceramic reinforcing fiber 4 Ceramic base material 5 Preform 6 Wire 11 Water tank 12 Pump casing 12a Bell mouth 12b Discharge elbow 13 Main shaft 14 Impeller 15 Shaft seal device 16 Joint 18, 19 Bearing 20 Elastic body 21 Bearing casing 22 Rib 23 Mounting material

Claims (3)

  A ceramic fiber reinforced ceramic sliding part, wherein at least the sliding part is made of a ceramic matrix composite material having a ceramic reinforced fiber and a ceramic base material. The ceramic reinforcing fiber has a cylindrical shape, and includes a plurality of first ceramic reinforcing fibers extending in the axial direction and a plurality of second ceramic reinforcing fibers extending in the circumferential direction, and the first ceramic reinforcing fibers 2. The ceramic fiber reinforced ceramic sliding part according to claim 1, wherein the second ceramic reinforced fibers cross each other.   The ceramic fiber-reinforced ceramic sliding part according to claim 1 or 2, wherein the ceramic fiber-reinforced ceramic sliding part is a bearing sleeve.

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