Zirconia-based ceramic material for micro motor bearings and its preparation process

Abstract

The present invention relates to the field of ceramic materials, and in particular to a zirconium oxide-based ceramic material for micro motor bearings and a preparation process thereof, which comprises the following components by weight: 80-100 parts of zirconium oxide, 20-30 parts of aluminum oxide, and lubricating particles AB 5-15 parts, sintering aid 1-5 parts; wherein A is a transition metal element; B is a VIA element. After testing, the ceramic material prepared by the present invention has a low friction coefficient at room temperature and high temperature, and has good friction and wear properties, and is a high-quality raw material for making micro motor bearings.

Description

Technical Field

[0001] The invention relates to the field of ceramic materials, in particular to a zirconium oxide-based ceramic material for micro motor bearings and a preparation process thereof. Background Art

[0002] Ceramic sliding bearings are widely used in engineering practice due to their high precision, corrosion resistance and long life. Due to their unique physical and chemical properties, they perform better than metal sliding bearings in specific applications. Zirconia has good high temperature stability and good mechanical strength, and is the main raw material for the production of sliding bearings. However, the disadvantage of high friction coefficient seriously limits the application of zirconia ceramics. Summary of the invention

[0003] Purpose of the invention: In view of the above technical problems, the present invention proposes a zirconia-based ceramic material for micro motor bearings and a preparation process thereof.

[0004] The technical solutions adopted are as follows:

[0005] A zirconium oxide-based ceramic material for micro motor bearings, comprising the following components in parts by weight:

[0006] Zirconia 80-100 parts, aluminum oxide 20-30 parts, lubricating particles AB 5-15 parts, sintering aid 1-5 parts;

[0007] Wherein, A is a transition metal element;

[0008] B is a VI A element.

[0009] Furthermore, A is any one or more combinations of Cu, Zn, Mn and Ni.

[0010] Furthermore, B is S or Se.

[0011] Furthermore, the lubricating particles AB are ZnS.

[0012] Furthermore, the ZnS is a flake structure.

[0013] Furthermore, the preparation method of the ZnS is as follows:

[0014] Thioacetamide and water-soluble zinc salt are added to ethylene glycol and mixed, and then sodium hydroxide solution and surfactant are added. The obtained mixed solution is subjected to solvent thermal reaction at a temperature of 160-200° C. for 8-24 hours. After the reaction is completed, the product is collected, washed and dried.

[0015] Furthermore, the surfactant is hexadecyltrimethylammonium bromide and polyvinylpyrrolidone in a mass ratio of 1-5:1-5.

[0016] Furthermore, the sintering aid is any one or more combinations of calcium oxide, boron oxide, silicon oxide, yttrium oxide, cerium oxide, lanthanum oxide, titanium oxide, and magnesium oxide.

[0017] Furthermore, the sintering aid is yttrium oxide and lanthanum oxide in a mass ratio of 1-5:1-5.

[0018] The present invention provides a method for preparing a zirconium oxide-based ceramic material for a micro motor bearing:

[0019] Zirconium oxide, aluminum oxide, lubricating particles AB and sintering aids are mixed and ball-milled, and then dried to obtain a mixed powder. A binder is added to the mixed powder to granulate and sieve to obtain pellets. The pellets are pressed into shape, and then debinding and sintering are performed in an argon atmosphere.

[0020] Beneficial effects of the present invention:

[0021] The invention provides a zirconia-based ceramic material for micro-motor bearings. ZnS is a hexagonal closest-packed layered structure, has extremely low shear strength in the direction parallel to the plane of the layer, and has extremely high strength and hardness in the vertical direction, and has an extremely low sliding friction coefficient. However, there are relatively few studies on the use of sheet-like structure ZnS for ceramic lubrication, because this two-dimensional crystallization mode with limited size in one direction is very easy to curl and generate a more compact spherical or tubular structure. The inventors finally obtain ZnS with a micro-nano size of sheet-like structure by controlling sulfur source, zinc source, surfactant, solvent and reaction conditions, and add it to the zirconia-based ceramic material, thereby reducing the friction coefficient of the ceramic material at room temperature and high temperature, improving the friction and wear performance, and the special sheet-like structure can improve the mechanical locking strength of the zirconia matrix and ZnS, thereby improving the stress transfer efficiency inside the ceramic material, and improving the mechanical strength of the zirconia-based ceramic material. After testing, the ceramic material prepared by the invention has a low friction coefficient at room temperature and high temperature, good friction and wear performance, and is a high-quality raw material for making micro-motor bearings. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a SEM image of the lubricating particles ZnS prepared in Example 1;

[0023] Figure 2 This is the SEM image of commercially available ZnS in Comparative Example 1. DETAILED DESCRIPTION

[0024] If the specific conditions are not specified in the examples, the experiments were carried out under conventional conditions or the conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially. The techniques not mentioned in the present invention are all referenced to the prior art. Unless otherwise specified, the following examples and comparative examples are parallel experiments, using the same processing steps and parameters.

[0025] Embodiment 1:

[0026] A zirconium oxide-based ceramic material for micro motor bearings, comprising the following components in parts by weight:

[0027] 95 parts of zirconium oxide, 25 parts of aluminum oxide, 10 parts of lubricating particles ZnS, 1 part of yttrium oxide, and 1 part of lanthanum oxide;

[0028] Wherein, the preparation method of lubricating particles ZnS is as follows:

[0029] 30g of thioacetamide and 1.6g of zinc chloride were added to 1.5L of ethylene glycol and mixed, and then 800ml of 0.01mol / L sodium hydroxide solution was added dropwise. After the addition, a surfactant consisting of 5g of hexadecyltrimethylammonium bromide and 5g of polyvinylpyrrolidone was added. The obtained mixed solution was sealed and heated to 180℃ for solvent thermal reaction for 12h. After the reaction was completed, the room temperature was restored, and the product was collected, washed repeatedly with anhydrous ethanol and water, and dried in an oven at 80℃ for 24h to obtain lubricating ZnS particles with a flaky structure. The SEM image is shown in FIG. Figure 1 .

[0030] Preparation method of the above-mentioned zirconium oxide-based ceramic material for micro motor bearings:

[0031] Zirconium oxide, aluminum oxide, lubricating particles ZnS, yttrium oxide, and lanthanum oxide are added to a ball mill, and water is used as the ball milling medium. The mixture is mixed and ball-milled in a planetary ball mill for 5 hours and then dried to obtain a mixed powder. 8wt% polyvinyl alcohol solution is added to the mixed powder as a binder to granulate and pass through an 80-mesh sieve to obtain granules. The granules are first dry-pressed at 40MPa and then cold isostatically pressed at 100MPa to obtain a green body. Under an argon atmosphere at normal pressure, the green body is first heated to 650℃ at a rate of 1℃ / min and kept for 1h for debinding, and then heated to 1350℃ at a rate of 10℃ / min and kept for sintering for 4h. The flexural strength is measured on a tensile testing machine using the three-point bending method, and the sample size is 30mm×3mm×4mm, the bending span is 20mm, and the axial loading speed is 0.5mm / min.

[0032] Embodiment 2:

[0033] A zirconium oxide-based ceramic material for micro motor bearings, comprising the following components in parts by weight:

[0034] 100 parts of zirconium oxide, 30 parts of aluminum oxide, 10 parts of lubricating particles ZnS, 1 part of yttrium oxide, and 1 part of lanthanum oxide;

[0035] Wherein, the preparation method of lubricating particles ZnS is the same as that of Example 1;

[0036] Preparation method of the above-mentioned zirconium oxide-based ceramic material for micro motor bearings:

[0037] Zirconium oxide, aluminum oxide, lubricating particles ZnS, yttrium oxide, and lanthanum oxide are added to a ball mill, and water is used as the ball milling medium. The mixture is mixed and ball-milled in a planetary ball mill for 5 hours and then dried to obtain a mixed powder. 8wt% polyvinyl alcohol solution is added to the mixed powder as a binder to granulate and pass through an 80-mesh sieve to obtain granules. The granules are first dry-pressed at 40MPa and then cold isostatically pressed at 100MPa to obtain a green body. Under an argon atmosphere at normal pressure, the green body is first heated to 650℃ at a rate of 1℃ / min and kept for 1h for debinding, and then heated to 1350℃ at a rate of 10℃ / min and kept for sintering for 4h. The flexural strength is measured on a tensile testing machine using the three-point bending method, and the sample size is 30mm×3mm×4mm, the bending span is 20mm, and the axial loading speed is 0.5mm / min.

[0038] Embodiment 3:

[0039] A zirconium oxide-based ceramic material for micro motor bearings, comprising the following components in parts by weight:

[0040] 80 parts of zirconium oxide, 20 parts of aluminum oxide, 10 parts of lubricating particles ZnS, 1 part of yttrium oxide, and 1 part of lanthanum oxide;

[0041] Wherein, the preparation method of lubricating particles ZnS is the same as that of Example 1;

[0042] Preparation method of the above-mentioned zirconium oxide-based ceramic material for micro motor bearings:

[0043] Zirconium oxide, aluminum oxide, lubricating particles ZnS, yttrium oxide, and lanthanum oxide are added to a ball mill, and water is used as the ball milling medium. The mixture is mixed and ball-milled in a planetary ball mill for 5 hours and then dried to obtain a mixed powder. 8wt% polyvinyl alcohol solution is added to the mixed powder as a binder to granulate and pass through an 80-mesh sieve to obtain granules. The granules are first dry-pressed at 40MPa and then cold isostatically pressed at 100MPa to obtain a green body. Under an argon atmosphere at normal pressure, the green body is first heated to 650℃ at a rate of 1℃ / min and kept for 1h for debinding, and then heated to 1350℃ at a rate of 10℃ / min and kept for sintering for 4h. The flexural strength is measured on a tensile testing machine using the three-point bending method, and the sample size is 30mm×3mm×4mm, the bending span is 20mm, and the axial loading speed is 0.5mm / min.

[0044] Embodiment 4:

[0045] A zirconium oxide-based ceramic material for micro motor bearings, comprising the following components in parts by weight:

[0046] 100 parts of zirconium oxide, 25 parts of aluminum oxide, 5 parts of lubricating particles ZnS, 1 part of yttrium oxide, and 1 part of lanthanum oxide;

[0047] Wherein, the preparation method of lubricating particles ZnS is the same as that of Example 1;

[0048] Preparation method of the above-mentioned zirconium oxide-based ceramic material for micro motor bearings:

[0049] Zirconium oxide, aluminum oxide, lubricating particles ZnS, yttrium oxide, and lanthanum oxide are added to a ball mill, and water is used as the ball milling medium. The mixture is mixed and ball-milled in a planetary ball mill for 5 hours and then dried to obtain a mixed powder. 8wt% polyvinyl alcohol solution is added to the mixed powder as a binder to granulate and pass through an 80-mesh sieve to obtain granules. The granules are first dry-pressed at 40MPa and then cold isostatically pressed at 100MPa to obtain a green body. Under an argon atmosphere at normal pressure, the green body is first heated to 650℃ at a rate of 1℃ / min and kept for 1h for debinding, and then heated to 1350℃ at a rate of 10℃ / min and kept for sintering for 4h. The flexural strength is measured on a tensile testing machine using the three-point bending method to be 875.4MPa. The sample size is 30mm×3mm×4mm, the bending span is 20mm, and the axial loading speed is 0.5mm / min.

[0050] Comparative Example 1:

[0051] The same as Example 1, except that commercially available non-flaky ZnS (Tongrun Nanotechnology, SEM image see Figure 2) replaced the self-made lubricating particles ZnS, and the flexural strength was measured on a tensile testing machine using the three-point bending method, which was 840.5MPa. The sample size was 30mm×3mm×4mm, the bending span was 20mm, and the axial loading speed was 0.5mm / min.

[0052] Comparative Example 2:

[0053] It is basically the same as Example 1, except that no lubricating particles ZnS are added, and the flexural strength is measured by the three-point bending method on a tensile testing machine to be 834.3 MPa, the sample size is 30 mm×3 mm×4 mm, the bending span is 20 mm, and the axial loading speed is 0.5 mm / min.

[0054] Comparative Example 3:

[0055] It is basically the same as Example 1, except that yttrium oxide is not added. The flexural strength is measured by the three-point bending method on a tensile testing machine to be 862.7 MPa, the sample size is 30 mm×3 mm×4 mm, the bending span is 20 mm, and the axial loading speed is 0.5 mm / min.

[0056] Comparative Example 4:

[0057] It is basically the same as Example 1, except that lanthanum oxide is not added. The flexural strength is measured by the three-point bending method on a tensile testing machine to be 855.1 MPa, the sample size is 30 mm×3 mm×4 mm, the bending span is 20 mm, and the axial loading speed is 0.5 mm / min.

[0058] Performance Test:

[0059] The ceramic materials prepared in Examples 1-4 of the present invention and Comparative Examples 1-4 were used as samples to carry out performance tests on a friction and wear testing machine to test the friction coefficient and wear rate of the samples. The samples were fixed on a rotating table connected to a motor, and a grinding ball was fixed on one end of a loading rod, and a weight could be placed on the other end as a load. A WC ceramic ball (HRA: 90.5) with a diameter of 3 mm was selected as the friction pair.

[0060] During the room temperature experiment, the load was 15N, the sliding linear speed was 0.3m / s, and the test time was 300min.

[0061] During high-temperature friction, the experimental temperature was 600°C, the heating rate was 10°C / min, the load was 15 N, the sliding linear speed was 0.3 m / s, and the test time was 60 min.

[0062] The dimensional parameters of the wear scar section were measured by LK-120DE surface profiler. Ten points were selected for each sample to take the average value. The surface profile was integrated using Origin software to obtain the cross-sectional wear volume. The wear rate was calculated using the following formula:

[0063] W= ;

[0064] Where W is the wear rate (mm 3 / Nm), V is the wear volume (mm 3 ), F is the load (N), and L is the distance of friction sliding (m).

[0065] The test results are shown in Table 1 below:

[0066] Table 1:

[0067] ;

[0068] It can be seen from Table 1 above that the ceramic material prepared by the present invention has a low friction coefficient at room temperature and high temperature and good friction and wear performance.

[0069] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A zirconium oxide-based ceramic material for micro motor bearings, characterized in that: The composition is calculated by weight: 80-100 parts of zirconium oxide, 20-30 parts of aluminum oxide, 5-15 parts of lubricating particles AB, and 1-5 parts of sintering aid; The lubricating particles AB are ZnS; The ZnS is a flake structure; The preparation method of the ZnS is as follows: Thioacetamide and water-soluble zinc salt are added to ethylene glycol and mixed, and then sodium hydroxide solution and surfactant are added, and the obtained mixed solution is subjected to solvent thermal reaction at a temperature of 160-200° C. for 8-24 hours. After the reaction is completed, the product is collected, washed and dried; The surfactant is hexadecyltrimethylammonium bromide and polyvinylpyrrolidone in a mass ratio of 1-5:1-5; The sintering aid is yttrium oxide and lanthanum oxide in a mass ratio of 1-5:1-5.

2. A method for preparing a zirconium oxide-based ceramic material for micro motor bearings as claimed in claim 1, characterized in that: Zirconium oxide, aluminum oxide, lubricating particles AB and sintering aids are mixed and ball-milled, and then dried to obtain a mixed powder. A binder is added to the mixed powder to granulate and sieve to obtain pellets. The pellets are pressed into shape, and then debinding and sintering are performed in an argon atmosphere.

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