JPH1053455A - Ceramic sliding member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a ceramic sliding member, having a low friction coefficient and excellent in durable strength by dispersing a specific compound or a specified slid solution in prescribed ceramics as the mother phase. SOLUTION: This ceramic sliding member is obtained by dispersing one or more compounds or solid solutions 3 selected from elements of Ge, Sc, Nb, Fe, Na, Ba, Ti, Cs, V, Mo and Ca (e.g. Fe3 O4 +TiO2 ) in one or more ceramics selected from Al2 O3 , ZrO2 , SiC, Si3 N4 and Si oxynitrides (e.g. Al2 O3 ) as the mother phase 2 or dispersing one or more compounds or slid solutions 3 selected from Ti compounds or solid solutions and one or more compounds or solid solutions 3 selected from elements of Fe, Na, Ba, V and Mo in one or more ceramics selected from Al2 O3 , ZrO2 , SiC, Si3 N4 and Si oxynitrides as the mother phase 2. The amount of the added compounds is preferably <=50wt.%, based on the total amount and expressed in terms of Si oxides.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic sliding member having a low coefficient of friction in water and excellent wear resistance.

[0002]

2. Description of the Related Art Conventionally, as disclosed in JP-A-6-93277 and JP-A-7-108774,
As a material for reducing the coefficient of friction in water, alumina-like surface coated with diamond-like carbon, alumina-coated surface with a mixture of silicon carbide and carbon, and a number of pores serving as water pools Known are ceramics, solid lubricants, and oil-impregnated ceramics that are uniformly dispersed. However, the conventional one has disadvantages in that the strength of the material is insufficient, the coating serving as a lubricating material is easily peeled off, and the cost is high.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a ceramic sliding member having a small friction coefficient and a high durability, in view of the above-mentioned problems.

[0004]

Means for Solving the Problems To solve the above problems, the present invention comprises alumina, zirconia, silicon carbide,
A ceramic composed of one or more compounds of silicon nitride and silicon oxynitride is used as a mother phase, and germanium, scandium, niobium, iron, sodium, barium, titanium, cesium, vanadium, molybdenum, It is characterized in that at least one compound or solid solution selected from the group of calcium elements is dispersed.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A polar liquid such as water is more likely to adhere to a solid surface as the electric field (electrostatic field) dispersed on the solid surface is stronger. It has the property of easily accumulating. Therefore, in order to obtain a ceramic sliding member having a small friction coefficient and a high durability, a ceramic phase having excellent mechanical properties is used as a mother phase, and a compound phase that generates an electric field is dispersed in the mother phase. More specifically, a relatively high-strength ceramic, such as alumina, is used as a mother phase, and a compound that generates a strong electric field in the mother phase, that is, a compound that is easily charged, is dispersed. By enlarging the field part,
Makes it easier to hold the water film.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, a ceramics sliding member according to the present invention is a ceramics sintered body mainly used for a water stop valve for a mixer tap, and is made of alumina (Al ₂₎ having a relatively high mechanical strength. O ₃ ), zirconia (ZrO ₂ ), silicon carbide (SiC
), Silicon nitride (Si ₃ N ₄ ), and oxynitride of silicon (Si), at least one selected from the group consisting of a ceramic and a crystal grain boundary 3 inside the mother phase 2. , Generating strong electric field, germanium (Ge), scandium (S
c), niobium (Nb), iron (Fe), sodium (Na), barium (Ba), titanium (Ti), cesium (Cs), vanadium (V), molybdenum (Mo), and calcium (Ca) A compound or solid solution of at least one selected element is dispersed.

The ceramic sliding member according to the present invention has a relatively high mechanical strength, such as alumina (Al ₂ O ₃ ), zirconia (ZrO ₂ ), silicon carbide (SiC), and silicon nitride (Si ₃ N).
₄ ), a ceramic composed of at least one selected from silicon oxynitrides (SiON) as a mother phase, and a titanium (Ti) compound or solid solution, iron (Fe), sodium ( At least one element selected from Na), barium (Ba), vanadium (V), and molybdenum (Mo) or a solid solution is dispersed.

The above-mentioned silicon carbide and silicon nitride are produced by a reaction sintering method. The addition amount of the compound of the above-mentioned element is converted to silicon oxide, and the total amount is 50 wt.
% Or less.

The titanium (Ti) compound or solid solution in the ceramic sintered body according to the present invention reduces the crystal grains of the matrix and increases the crystal grain boundary portion. It is desirable that the average particle diameter of the crystal grains of the mother phase be 5 μm or less.
When the average particle diameter exceeds 5 μm, the coefficient of friction increases, and the contact angle of water also increases.

[Example 1] (Samples 1A to 1J) Several kinds of compound powders which use alumina (Al ₂ O ₃ ) powder as a main raw material and easily generate an electric field in the alumina powder (Samples 1A to 1J in Table 1)
1J), a molded article having a predetermined shape was formed from the mixed powder, and the molded article was fired in an air atmosphere at a temperature of 1600 ° C. to obtain a composite ceramic having alumina as a mother phase. Diameter 40 from the composite ceramics
A disk-shaped test piece having a thickness of 5 mm and a thickness of 5 mm was prepared, and the surface of the test piece was smoothed by lapping. The obtained two test pieces were overlapped and slid with each other in water to measure the coefficient of friction. In addition, the contact charge amount (electric field strength) of each test piece was measured using a capacitance type surface electrometer.

Tables 1 and 2 show the contact charge amount of the test piece (sample), the coefficient of friction in hot water at 80 ° C., and the strength. As is clear from Tables 1 and 2, the strength of the electric field varies depending on the type of the additive, and if the material is easily charged (a material having a large contact charge amount), the friction coefficient in water is small.
Conversely, it can be seen that a material that is difficult to be charged has a high coefficient of friction in water. As a result of measuring the contact angle of water with each test piece, it was found that the material to which a compound having a strong electric field was added had excellent wettability or adhesion to water.

As a comparative example, in the same manner as in Example 1, alumina (Al ₂ O ₃ ) powder was used as a main raw material, and a compound powder which hardly generates an electric field was added to or added to the alumina powder (sample 1K in Table 1). To 1N), a ceramic having alumina as a mother phase was prepared, a test piece was prepared from the ceramic in the same manner as in Example 1, and the coefficient of friction of the test piece was measured.

[0013]

[Table 1] [Example 2] (Sample 2A-2H) Itsutoria (Y ₂ O ₃₎ powder and partially stabilized zirconia (Zr
O ₂ ) powder as a main raw material, compound powder that generates an electric field (Table 1)
, And molded into a predetermined shape from the mixed powder, and the molded body is sintered to form a composite ceramic having yttria and partially stabilized zirconia as a mother phase. Created. In the same manner as in Example 1, a test piece was prepared from a composite ceramic having yttria and partially stabilized zirconia as a matrix, and the coefficient of friction of the test piece was measured.

As a comparative example, in the same manner as in Example 2, ituria (Y ₂ O ₃ ) powder and partially stabilized zirconia (ZrO ₂ )
Powder is used as a main material, and a compound powder that does not easily generate an electric field is added or not added (see Samples 2I to 2K in Table 1) to prepare a composite ceramics containing yttria and partially stabilized zirconia as a mother phase. Test pieces were prepared from the ceramics in the same manner as in Example 1, and the friction coefficients of the test pieces were measured.

[Example 3] (Samples 3A to 3E) Compound powder generating an electric field using silicon powder, carbon powder, and silicon carbide (SiC) powder as main raw materials (Sample 3 in Table 2)
A to 3E), a molded body having a predetermined shape was formed from the mixed powder, and the molded body was sintered to prepare a composite ceramic having reaction sintered silicon carbide as a mother phase. In the same manner as in Example 1, a test piece was prepared from the composite ceramics using reaction sintered silicon carbide as a matrix, and the friction coefficient of the test piece was measured.

As a comparative example, in the same manner as in Example 3, silicon powder, carbon powder, and silicon carbide powder were used as main raw materials, and a compound powder which hardly generates an electric field was added or not (samples in Table 2). 3F, 3G), a composite ceramics having reaction sintered silicon carbide as a mother phase was prepared, a test piece was prepared from the composite ceramics in the same manner as in Example 1, and the friction coefficient of the test piece was measured.

[0017]

[Table 2] [Example 4] (Samples 4A to 4E) Using silicon powder as a main raw material, a small amount of a sintering aid powder and a compound powder generating an electric field (see Samples 4A to 4E in Table 2) were added to the silicon powder. A molded article having a predetermined shape was formed from the mixed powder, and the molded article was subjected to reaction sintering in a nitrogen atmosphere at a temperature of 1400 ° C., thereby producing a composite ceramic having reaction sintered silicon nitride as a mother phase. In the same manner as in Example 1, a test piece was prepared from the composite ceramics containing reaction sintered silicon nitride as a matrix, and the friction coefficient of the test piece was measured.

As a comparative example, in the same manner as in Example 4, silicon powder was used as a main material, a small amount of a sintering aid powder was added to the silicon powder, and a compound powder that hardly generates an electric field was added or not. (See Samples 4F and 4G in Table 2), a composite ceramic having a reaction sintered silicon nitride as a mother phase was prepared, and a test piece was prepared from the composite ceramic in the same manner as in Example 1; The coefficient was measured.

[Example 5] (Samples 5A to 5E) A mixed powder of silicon and silicon oxide was used as a main raw material, and a compound powder which generates an electric field (see Samples 5A to 5E in Table 2) was added. Forming a molded body of a predetermined shape from powder,
The molded body was subjected to two-stage sintering in a nitrogen atmosphere at a temperature of 1600 ° C. to produce a composite ceramic having silicon oxynitride (SiON) as a mother phase.

As a comparative example, in the same manner as in Example 5, a mixed powder of silicon and silicon oxide was used as a main raw material, and a compound powder which hardly generates an electric field was added or not added (Sample 5 in Table 2).
F, 5G), a composite ceramic having silicon oxynitride (SiON) as a matrix was prepared, and a test piece was prepared from the composite ceramic in the same manner as in Example 1, and the friction coefficient of the test piece was measured. It was measured.

Example 6 The tensile strength of the composite ceramics containing alumina as a mother phase was measured when the amount of the compound was changed. As shown in FIG. 2, when the added amount of the compound exceeded 50 wt%, the sinterability was remarkably deteriorated, and the strength was lowered.

Example 7 With respect to the composite ceramics containing alumina as a matrix, the friction coefficient was measured when the average particle size of the sintered body was adjusted by changing the firing temperature. As shown in FIG. 3, it was found that when the average particle size exceeds 5 μm, the coefficient of friction increases and the contact angle of water also increases. From the above results, it is desirable that the average particle diameter of the composite ceramics containing alumina as a mother phase be 5 μm or less.

[Embodiment 8] Of the composite ceramics shown in Embodiment 1 and having alumina as a mother phase, alumina powder is used as a main material and ferric oxide (Fe ₃ O ₄ ) and titanium oxide (TiO ₂ ).
A water shutoff valve for a mixing plug was formed from a mixture containing the powders of (a) and ( _b ), and a powder of vanadium oxide (V ₂ O ₅ ) and titanium oxide (TiO ₂ ) as a main raw material. Tied. The obtained water stop valve for a mixing tap showed little wear even after 200,000 times of repeated opening / closing operations, and also showed a good water stop torque (tightening torque for valve closing operation).

[0024]

According to the present invention, as described above, at least one of alumina, zirconia, silicon carbide, silicon nitride, and silicon oxynitride is used as a ceramic sliding member as a mother phase. And at least one compound or solid solution selected from the group consisting of germanium, scandium, niobium, iron, sodium, barium, titanium, cesium, vanadium, molybdenum, and calcium is dispersed in the matrix. Because of this, the compound or solid solution generates a strong electric field at the crystal grain boundary portion, and has an effect of maintaining a water film well and reducing a friction coefficient in water. Therefore, if the ceramic sliding member according to the present invention is used for a water stop valve for a mixer tap, a valve having excellent wear resistance and light valve operation can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing the structure of a ceramic sliding member according to the present invention.

FIG. 2 is a diagram showing the relationship between the amount of compound added and the tensile strength of the composite ceramics having alumina as a mother phase as the ceramics sliding member.

FIG. 3 is a diagram showing a relationship between an average particle diameter and a friction coefficient of a composite ceramics containing alumina as a mother phase as the ceramics sliding member.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location C04B 35/584 C04B 35/56 101A 35/58 301 35/58 102A

Claims (5)

[Claims] The present invention relates to at least one of alumina, zirconia, silicon carbide, silicon nitride and silicon oxynitride as a mother phase, and germanium, scandium, niobium, iron, sodium, barium, and titanium. ,cesium,
A ceramic sliding member, wherein at least one compound or solid solution selected from the group consisting of vanadium, molybdenum and calcium is dispersed. 2. A ceramic comprising at least one of alumina, zirconia, silicon carbide, silicon nitride and silicon oxynitride as a mother phase, a titanium titanium compound or solid solution, iron, sodium and barium. A sliding member, wherein at least one compound or solid solution selected from the group consisting of vanadium, molybdenum and molybdenum is dispersed. 3. The ceramic sliding member according to claim 1, wherein the amount of the compound is 50 wt% or less of the total amount in terms of silicon oxide. 4. The ceramic sliding member according to claim 1, wherein said silicon carbide and said silicon nitride are produced by a reaction sintering method. 5. The ceramic sliding member according to claim 1, wherein said ceramic sliding member is used for a water stop valve for a mixer tap.