JP2007198519A - Insulating roller bearing for preventing electric corrosion - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve all of an ensured insulating property, ensured durability, and a good appearance at high levels. <P>SOLUTION: A ceramic containing 97% by weight or more of alumina, and 0.5 to 2.5% by weight or more of zirconia is used as a ceramic which constitutes a insulating coating film 6, i.e., a ceramic spraying layer. As this ceramic contains 97% by weight or more of alumina, the insulating property can be ensured. Further, as this ceramic contains 0.5 to 2.5% by weight or more of zirconia, durability can be ensured, and deterioration in appearance after sealing treatment can be prevented. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an improvement in an insulating rolling bearing for preventing electric corrosion that is incorporated in a rotation support portion in which a current may flow, such as a rotating shaft of a general-purpose or railway vehicle electric motor or a rotating shaft of a generator.

  In the case of a rolling bearing for supporting rotating shafts of various electric devices such as an electric motor and a generator, currents such as a return current and a motor shaft current flow in the rolling bearing itself unless measures are taken. When an electric current flows through the rolling bearing, so-called electric corrosion occurs, ie, corrosion of a portion serving as a current path progresses, and the life of the rolling bearing is significantly shortened. In order to prevent the occurrence of such electric corrosion, by forming an insulating layer on the surface of the outer ring and the inner ring constituting the rolling bearing, an insulating rolling bearing for preventing electric corrosion that prevents current from flowing through the rolling bearing is provided. For example, as described in Patent Documents 1 to 3, it is conventionally known.

  Each of the insulating type rolling bearings described in each of these patent documents has an insulating layer made of ceramic, synthetic resin or the like formed on a portion of the bearing ring constituting the rolling bearing that is supported by the mating member. For example, it is configured as shown in FIG. In the rolling bearing, a plurality of rolling elements 5 are provided between an inner ring raceway 2 formed on the outer peripheral surface of the inner ring 1 and an outer ring raceway 4 formed on the inner peripheral surface of the outer ring 3. Relative rotation is free. And the insulating layer 6 which is a ceramic sprayed layer is formed in the outer peripheral surface of this outer ring | wheel 3, and an axial direction both end surface. In the case of such an insulating rolling bearing for preventing electric corrosion, the insulating layer 6 insulates the outer ring 3 from the housing in a state where the outer ring 3 is fitted and supported in a metal housing. As a result, current does not flow between the outer ring 3 and the housing, and the above-described electrolytic corrosion does not occur in the constituent members 1, 3, and 5 of the rolling bearing.

However, in the case of an insulating rolling bearing for preventing electric corrosion that has been conventionally known, as described in Patent Documents 1 to 3 above, ensuring insulation performance, ensuring durability, and reducing costs are arranged in a high dimension. It was difficult. The reason is as follows. For example, when the insulating layer 6 that is a ceramic sprayed layer is formed on the surface of the outer ring 3, the ceramic sprayed layer is formed on the outer peripheral surface 7 by moving the spray nozzle along the outer peripheral surface 7 of the outer ring 3. At the same time, a ceramic sprayed layer is formed on both axial end surfaces 8 and 8 by moving the thermal spray nozzle along the axial end surfaces 8 and 8 of the outer ring 3. Conventionally, the ceramic sprayed layer formed in this way is 0.5 mm or more (generally 0.6 mm by spraying a droplet of a ceramic material containing 94 to 95% by weight of alumina (Al ₂ O ₃ ). The one having a thickness dimension of about 0.7 mm was formed.

  In order to form the ceramic sprayed layer on each of the surfaces 7 and 8 as described above, the bent continuous portions 9 and 9 existing between the axial end surfaces 8 and 8 and the outer peripheral surface 7 are provided from both nozzles. Thermal sprayed ceramic adheres. For this reason, the thickness dimension of the bent continuous portions 9, 9 becomes larger than the thickness dimension of the outer peripheral surface 7 and both axial end surfaces 8, 8. As a result, when the thickness dimension of each of the surfaces 7 and 8 is set to a sufficient value from the viewpoint of securing the insulation performance, the thickness dimension of the both bent continuous portions 9 and 9 becomes excessive. The ceramic sprayed layer is brittle, and if the thickness dimension is excessive, damage such as cracking and chipping is likely to occur. Since the bent continuous portions 9 and 9 themselves do not come into contact with other parts such as the housing, even if the ceramic sprayed layer is damaged, it is unlikely to cause a problem in terms of ensuring insulation. If it enters the rolling bearing, it is not preferable because damages such as indentations are likely to occur on the inner ring raceway 2, the outer ring raceway 4 and the rolling surfaces of each rolling element 5. For this reason, conventionally, the portion of the ceramic sprayed layer covering the bent continuous portions 9, 9 has also been reduced in thickness by polishing. Polishing the surface portions of these bent continuous portions 9 and 9 causes an increase in cost.

  Conventionally, the inventions described in Patent Documents 4 to 5 are known as techniques for preventing damage to a ceramic insulating layer. Of these, the invention described in Patent Document 4 improves the toughness of an insulating layer by impregnating a ceramic insulating layer with a synthetic resin. The invention described in Patent Document 5 prevents the ceramic sprayed layer from being lost by covering the ceramic insulating layer with a metal layer. However, in the case of the inventions described in Patent Documents 4 to 5, the manufacturing work is troublesome and the cost cannot be reduced.

On the other hand, Patent Document 6 describes an invention related to an electric rolling prevention insulating rolling bearing having an insulating layer made of gray alumina containing titanium oxide (TiO ₂ ) in an amount of 1% by weight or less. As described in Patent Document 6, when only ensuring performance (insulation resistance value) as an insulating layer is considered, white alumina, which is pure alumina not containing titanium oxide, is more titanium oxide. It is superior to gray alumina containing. However, as described in Patent Document 6 described above, in the case of white alumina, the yield of the material (alumina grains) at the time of forming the sprayed layer is poor and the cost increases. For this reason, in the case of the invention described in Patent Document 6, the use of gray alumina having the above composition secures insulation performance while suppressing an increase in cost.

  However, according to experiments conducted by the inventors of the present invention, it has been found that the gray alumina having the composition described in Patent Document 6 cannot always ensure sufficient insulation performance. On the other hand, when white alumina is used, if the particle size of the sprayed alumina is properly controlled, the degree of cost increase is limited, but color unevenness occurs on the surface, which makes it look like a product. I found it worse. That is, the alumina sprayed layer has fine voids inside as it is, and the insulation performance deteriorates when moisture enters the voids. For this reason, after forming the sprayed layer of alumina, as described in Patent Document 7, it is necessary to perform a sealing treatment in which the gap is closed with a synthetic resin so that moisture does not enter the gap. is there. When the sprayed layer is formed of white alumina, color unevenness occurs on the surface of the sprayed layer along with the sealing treatment. Such uneven color is not a problem in terms of insulation performance, but is not preferable because it deteriorates the appearance of the product.

JP-A-1-182621 JP-A-5-52223 JP-A-5-31216 Japanese Utility Model Publication No. 60-85626 Japanese Utility Model Publication No. 6-2030 JP 2005-133876 A Japanese Patent Laid-Open No. 2003-183806

  In view of the circumstances as described above, the present invention can ensure insulation performance, ensure durability, and reduce costs at the same time, and can improve the appearance, and can prevent electric corrosion. It was invented to realize an insulated rolling bearing.

  As shown in FIG. 1, for example, as shown in FIG. 1, each of the insulated rolling bearings for preventing electric corrosion that is a subject of the present invention is a pair of raceways (for example, an inner ring 1 and an outer ring) that are made of metal. 3) and a pair of raceway surfaces (for example, the inner ring raceway 2 and the outer ring raceway 4) formed on the surfaces of the two race rings 1, 3 facing each other. A plurality of rolling elements (for example, balls) 5 that are manufactured. In the case of a surface other than the surface provided with the raceway surface among the surfaces of at least one of the raceways 1 and 3, that is, in the case of a radial rolling bearing, (A) or ( As shown in B), one of the circumferential surfaces and both axial end surfaces are covered with a ceramic insulating layer 6 on one axial side surface and both inner and outer circumferential surfaces in the case of a thrust rolling bearing. .

In particular, in the insulating rolling bearing for preventing electric corrosion of the present invention, the insulating layer 6 is composed of 97% by weight or more of alumina (Al ₂ O ₃ ) and 0.5 to 2.5% by weight of zirconia (ZrO). ₂ ) and a ceramic sprayed layer containing.
The insulating layer 6 is preferably formed by polishing the surface of the ceramic sprayed layer formed other than the raceway surface. In this case, the thickness of the ceramic sprayed layer is 0.4 mm or less excluding the bent continuous part between the adjacent surfaces, and the thickness of the insulating layer obtained by polishing the ceramic sprayed layer, 0.25 mm or more.
In carrying out the present invention, it is preferable that the particle size is 10 for the purpose of improving the accuracy with respect to the thickness of the ceramic sprayed layer as the insulating layer and improving the adhesion efficiency of alumina constituting the ceramic sprayed layer. Alumina having an average particle diameter of 15 to 25 μm is used.

  Furthermore, as a method for regulating the thickness of the insulating layer described above, for example, there is the following method. That is, the ceramic sprayed layer containing 97% by weight or more of alumina and 0.5 to 2.5% by weight or more of zirconia, respectively, has a thickness of 0 excluding the bent continuous part between adjacent surfaces. The thickness is limited to 4 mm or less and is formed on a surface other than the surface provided with the raceway surface. Thereafter, the insulating layer having a thickness of 0.25 mm or more is obtained by polishing a portion of the ceramic sprayed layer other than the portion covering the bent portion.

According to the invention of the insulated rolling bearing for preventing electric corrosion of the present invention configured as described above, the insulation performance, the durability, the cost reduction, and the good appearance can be secured at a high level. Can be juxtaposed.
That is, among the ceramic sprayed layers mainly composed of alumina, white alumina containing no zirconia is excellent in insulation performance but deteriorates in appearance with the sealing treatment. On the other hand, in the case of the present invention, since it contains 0.5% by weight or more of zirconia, color unevenness that causes deterioration in appearance does not occur regardless of the sealing treatment. That is, a part of the synthetic resin appears on the surface of the ceramic sprayed layer in accordance with the sealing treatment for closing the fine voids existing inside the ceramic sprayed layer with the synthetic resin. In the case of white alumina whose surface color is close to pure white, the synthetic resin appearing on the surface in this way causes uneven color on the surface and deteriorates the appearance of the product. On the other hand, in the case of a ceramic material containing 0.5% by weight or more of zirconia, the color of the surface is gray (gray), so that the surface has a color unevenness that deteriorates the appearance of the product. It never happens.

However, if the zirconia exceeds 2.5% by weight, the thickness of the ceramic sprayed layer required to ensure the required insulation performance increases. Therefore, the content of the zirconia is restricted to a range of 0.5 to 2.5% by weight.
In addition, by suppressing the content of the zirconia in the ceramic sprayed layer to 2.5% by weight or less, the yield of the material (alumina grains) at the time of forming the sprayed layer is somewhat deteriorated. However, as described above, if alumina having a particle size of 10 to 50 μm and an average particle size of 15 to 25 μm is used, in addition to improving the adhesion efficiency of alumina constituting the ceramic sprayed layer, the above The accuracy related to the thickness dimension of the ceramic sprayed layer can be improved, and the cost increase can be suppressed. That is, it is possible to reduce the manufacturing cost of the anti-corrosion insulated rolling bearing by saving the material cost by improving the adhesion efficiency and facilitating the finishing process by shortening the dimensional accuracy (reducing the finishing time).
Further, in the case of the present invention, since the ceramic sprayed layer contains zirconia having high strength and high toughness, the adhesion of the ceramic sprayed layer can be improved. For this reason, sufficient durability can be secured.

Further, as described above, the insulating layer 6 is formed by polishing the surface of the ceramic sprayed layer formed other than the raceway surface, and the thickness of the ceramic sprayed layer is set between the adjacent surfaces. When the thickness of the insulating layer obtained by polishing the ceramic sprayed layer is 0.25 mm or more, excluding the continuous bent portion, the insulation performance is ensured and the durability is maintained. It is possible to achieve high performance and low cost at the same time.
That is, in the case of the above-described structure, a ceramic sprayed layer containing 97% by weight or more of alumina and 0.5 to 2.5% by weight or more of zirconia is used. Has a relatively large electric resistance value (having excellent insulating properties). Therefore, as long as the thickness of the insulating layer after polishing is secured to 0.25 mm or more, as long as the application is the rotating shaft of a general-purpose or railway vehicle electric motor or the rotating shaft of a generator, the electrolytic corrosion A sufficient prevention effect can be secured.
Moreover, in order to ensure the thickness of the insulating layer after polishing to be 0.25 mm or more, the polishing allowance can be sufficiently ensured even if the thickness of the ceramic sprayed layer before polishing is 0.4 mm or less. And if the thickness of this ceramic sprayed layer is restrained to 0.4 mm or less, the thickness of the ceramic sprayed layer which covered the bending continuous part between adjacent surfaces can be restrained to less than 0.5 mm. If it is a ceramic sprayed layer with a thickness of about 0.5 mm, it cannot be said that the thickness dimension is excessive, even if it is as it is (even if the thickness dimension is not reduced by polishing), cracks, chips, etc. Hard to cause damage. Therefore, it is possible to reduce the cost by omitting the trouble of polishing the portion of the ceramic sprayed layer covering the bent continuous portion. The cost can also be reduced by reducing the thickness of the ceramic sprayed layer (conventionally 0.5 mm or more to 0.4 mm or less).

2 to 3 show an example of an embodiment of the present invention. In the case of this example, the insulating layer 6a is formed on the outer peripheral surface 7 and both axial end surfaces 8 and 8 of the outer ring 3 constituting the single row deep groove type radial ball bearing. The insulating layer 6a sprays ceramic droplets containing 97% by weight or more of alumina and 0.5 to 2.5% by weight of zirconia on the outer peripheral surface 7 and both axial end surfaces 8 and 8 by plasma spraying. This is a ceramic sprayed layer. The insulating layer 6a, which is such a ceramic sprayed layer, is composed of the outer peripheral surface 7 and both axial end surfaces 8, 8 as well as both axial end edges of the outer peripheral surface 7 and the outer ends 8 and 8 of the axial direction. It also covers the surfaces of the bent continuous portions 9 and 9 having a circular arc shape with a quarter cross section that is continuous with the periphery. Of the thickness dimensions T ₇ , T ₈ , T ₉ (see FIG. 3) of the insulating layer 6a covering these surfaces, the surfaces of the outer peripheral surface 7 and the axial end surfaces 8, 8 are covered. The thickness dimensions T ₇ and T ₈ of the portion are suppressed to 0.4 mm or less. Then, by suppressing the thickness dimensions T ₇ and T ₈ of each part to 0.4 mm or less, the thickness dimension T ₉ of the part covering the surfaces of the both bent continuous parts 9 and ₉ is set to 0.5 mm. Less than.

Further, by polishing the portion of the insulating layer 6a covering the outer peripheral surface 7 and the surfaces of both axial end surfaces 8, 8, these portions are made smooth, and the surfaces 7, 8 and the above The inner surface of the housing to which the outer ring 3 is fitted and fixed is in close contact with the inner ring. With such polishing, the surface portion of the insulating layer 6a covering the surfaces 7 and 8 (the oblique lattice portion in FIG. 3) is removed by the polishing allowance δ shown in FIG. The thickness dimension of the insulating layer 6a is thinner than the state in which the ceramic sprayed layer is formed. However, the thicknesses t ₇ (= T ₇ −δ) and t ₈ (= T ₈ −δ) after the removal of the polishing allowance δ are secured to 0.25 mm or more. On the other hand, the portion of the insulating layer 6a that covers the surfaces of the bent portions 9 and 9 is left as it is (without spraying ceramic droplets) without being polished. Yes.

The insulating rolling bearing for preventing electric corrosion as described above can ensure the insulation performance of the insulating layer 6a, the durability, and the cost reduction in parallel.
First, the insulation performance can be ensured by using a ceramic sprayed layer constituting the insulating layer 6a containing 97% by weight or more of alumina. In other words, a ceramic sprayed layer containing 97% by weight or more of alumina has a large electrical resistance value (having excellent insulating properties), so that the thickness of the insulating layer after polishing (in use) can be secured at 0.25 mm or more. For example, as long as the application is a rotating support portion with a potential difference of up to about 3000 V, such as a rotating shaft of an electric motor for general purpose or railway vehicles, or a rotating shaft of a generator, the effect of preventing electrolytic corrosion can be sufficiently secured. For example, when the thickness dimension of the insulating layer after polishing is 0.25 mm, an insulation resistance value of 5000 MΩ or more can be secured under the condition of 1000 V applied.

  Further, in order to ensure the thickness of the insulating layer 6a after polishing to be 0.25 mm or more, it is sufficient (less than about 0.15 mm at maximum) even if the thickness of the ceramic sprayed layer before polishing is 0.4 mm or less. Polishing allowance can be secured. That is, the surface of the insulating layer 6a and the inner surface of the housing are uniformly contacted to stabilize the posture of the outer ring 3 and to prevent an excessive force from being applied to a part of the insulating layer 6a. Therefore, it is necessary to polish the portion covering the surfaces of the outer peripheral surface 7 and the axial end surfaces 8 and 8. Even in this case, since the necessary polishing allowance is 0.15 mm or less, even if the thickness of the ceramic sprayed layer before polishing is suppressed to 0.4 mm or less, the thickness of the insulating layer 6a after polishing is 0.25 mm. This can be secured.

Then, as long suppress the thickness of the thermally sprayed ceramic layer to 0.4mm or less, as described above, the thickness T ₉ of the portion covering the surface of both bent continuous section 9,9, less than 0.5mm Can be suppressed. That is, in these two bent continuous portions 9, 9, ceramic droplets that are ejected radially outward on the outer peripheral surface 7, and ceramic droplets that are ejected axially outward on the axial end surfaces 8, 8. Adheres. For this reason, the thickness dimension of the ceramic sprayed layer covering the two bent continuous portions 9, 9 is larger than the thickness dimension of the ceramic sprayed layer covering the outer peripheral surface 7 and the axial end surfaces 8, 8.

  In the case of this example, since the thickness dimension of the ceramic sprayed layer covering the surfaces 7 and 8 is suppressed to 0.4 mm or less, the thickness dimension of the ceramic sprayed layer covering the bi-folded continuous portions 9 and 9 is as follows. Can be suppressed to less than 0.5 mm. If it is a ceramic sprayed layer with a thickness of about 0.5 mm, it cannot be said that the thickness dimension is excessive, even if it is as it is (even if the thickness dimension is not reduced by polishing), cracks, chips, etc. Hard to cause damage. Accordingly, it is possible to reduce the cost by omitting the trouble of polishing the portion of the insulating layer 6a that is the ceramic sprayed layer that covers the bent portions 9 and 9.

  Further, in the case of this example, since 0.5% by weight or more of zirconia is contained, color unevenness that leads to deterioration in appearance does not occur regardless of the sealing treatment. That is, a part of the synthetic resin appears on the surface of the ceramic sprayed layer in accordance with the sealing treatment for closing the fine voids existing inside the ceramic sprayed layer with the synthetic resin. In the case of a ceramic material containing 0.5% by weight or more of zirconia, the surface color is gray, so use a resin with an appropriate color as the synthetic resin used for the sealing treatment. As a result, there is no uneven color on the surface to the extent that the appearance of the product is deteriorated.

However, if the zirconia exceeds 2.5% by weight, the thickness of the ceramic sprayed layer required to ensure the required insulation performance increases. Therefore, the content of the zirconia is restricted to a range of 0.5 to 2.5% by weight.
In addition, by suppressing the content of the zirconia in the ceramic sprayed layer to 2.5% by weight or less, the yield of the material (alumina grains) at the time of forming the sprayed layer is somewhat deteriorated. However, if alumina having a particle size of 10 to 50 μm and an average particle size of 15 to 25 μm is used, it is possible to improve the adhesion efficiency of alumina constituting the ceramic sprayed layer and to increase the thickness of the ceramic sprayed layer. The accuracy with respect to the height can be improved and the increase in cost can be suppressed. That is, it is possible to reduce the manufacturing cost of the anti-corrosion insulated rolling bearing by saving the material cost by improving the adhesion efficiency and facilitating the finishing process by shortening the dimensional accuracy (reducing the finishing time).
Furthermore, in the case of this example, since the ceramic sprayed layer contains zirconia having high strength and high toughness, the adhesion of the ceramic sprayed layer can be improved. As described above, if the adhesion of the ceramic sprayed layer is improved, the ceramic sprayed layer becomes difficult to peel off, and thus sufficient durability can be secured.

  An experiment conducted for confirming the effect of the present invention will be described. First, an experiment conducted for examining the adhesion (adhesion strength) of the ceramic sprayed layer will be described. This experiment was performed based on the adhesion test described in JIS H 8666. Moreover, as a material for the ceramic sprayed layer, white alumina, gray alumina containing 3.0% by weight of titanium oxide in alumina, 0.04% by weight of titanium oxide, and 1.25% by weight of zirconia are also used. Four types were prepared. In addition, an organic synthetic resin such as an epoxy resin or a fluorine resin was used as a synthetic resin used for sealing each ceramic sprayed layer formed of the above four types of materials. The film thickness of each ceramic sprayed layer was 0.35 mm (350 μm). The results of this experiment are shown in FIG. As is apparent from FIG. 4, the adhesion strength of white alumina and 0.04% by weight of titanium oxide was 60 to 64 MPa, whereas 1.25% by weight of zirconia was contained. It was found that the adhesive strength of the object was 69 MPa, which was high.

Next, an experiment conducted for examining the volume resistivity value of the ceramic sprayed layer will be described. In this experiment, the following seven types of materials were used.
(1) White alumina (2) Alumina containing 0.04% by weight of titanium oxide (3) Also containing 0.4% by weight of titanium oxide (4) Also containing 3.0% by weight of titanium oxide (5) The same containing 0.5% by weight of zirconia (6) The same containing 1.25% by weight of zirconia (7) The same containing 2.5% by weight of zirconia As a synthetic resin used for sealing treatment of each ceramic sprayed layer formed of a material, an organic synthetic resin such as epoxy or fluorine was used.

FIG. 5 shows the respective volume resistivity values when a voltage of 1000 V is applied to each ceramic sprayed layer formed of the materials (1) to (7). As is apparent from FIG. 5, the volume specific resistance value {(4)} containing 3.0% by weight of titanium oxide in alumina had the lowest volume value of 8.6 × 10 ¹² (Ω · cm). On the other hand, white alumina {(1)} is the highest at 5.0 × 10 ¹⁴ (Ω · cm), and then alumina contains 0.04 and 0.4% by weight of titanium oxide {( 2), (3)} and alumina containing 0.5 to 2.5% by weight of zirconia {(5) to (7)} are 1.0 to 2.5 × 10 ¹⁴ (Ω・ Cm) showed similar values. That is, zirconia has a smaller rate of decrease in volume resistivity with respect to increase in content than titanium oxide. Thereby, it turns out that the ceramic sprayed layer which contained 0.5 to 2.5 weight% of zirconia in the alumina has high insulation. In addition, what contained 3.0% by weight of titanium oxide in alumina {(4)} had to have a film thickness of 0.5 mm or more in order to ensure sufficient insulation, but zirconia was added to alumina. Those containing 0.5 to 2.5% by weight were able to secure sufficient insulation even if the film thickness was reduced. As a result, it can be seen that the material cost can be reduced.

  The present invention is not limited to the single row deep groove type radial ball bearing as shown in the figure, but other types of radial ball bearings such as angular type and double row, tapered roller bearings, cylindrical roller bearings, self-aligning roller bearings, Other types of rolling bearings such as thrust ball bearings or thrust roller bearings can also be used. In the case of a thrust rolling bearing, the insulating layer is formed on both the inner and outer peripheral surfaces and one axial surface.

Sectional drawing which shows two examples of the implementation condition of this invention. The fragmentary sectional view which shows the 1st example of embodiment of this invention. The A section enlarged view of FIG. The bar graph which shows the result of having measured the adhesive force of the ceramic sprayed layer. The bar graph which shows the result of having measured the volume resistivity value of the ceramic sprayed layer. The half part sectional view showing an example of conventional structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inner ring 2 Inner ring track 3 Outer ring 4 Outer ring track 5 Rolling element 6, 6a Insulating layer 7 Outer peripheral surface 8 End surface 9 Bending continuous part

Claims (1)

Rollers are provided between a pair of raceways arranged concentrically, each made of metal, and a pair of raceways formed on opposite surfaces of these raceways. A plurality of rolling elements each made of metal, and covering a surface of at least one of the two bearing rings other than the surface provided with the raceway surface with a ceramic insulating layer In the insulated rolling bearing for preventing electric corrosion, the insulating layer is a ceramic sprayed layer containing 97% by weight or more of alumina and 0.5 to 2.5% by weight of zirconia. Insulated rolling bearing for electric corrosion prevention.

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