Analytical methods, instrumental diagnostic methods, and ferrography apparatus

Abstract

This provides an analytical method that allows for the easy analysis of magnetic powders. [Solution] A mixture of oil containing magnetic powder and a solvent is prepared as a sample solution (Step A). ​​A ferrography apparatus 50 is prepared, comprising a long plate material 34 on which the sample solution is dropped, a base body 24 having a long planar area 25 on which the plate material 34 is placed, a long magnet 36 embedded in the planar area 25, and holding mechanisms 30, 32 that hold the base body 24 in an inclined state with one end of the magnet 36 higher than the other end (Step B). With the base body 24 held in an inclined state, the sample solution is dropped onto the higher side of the plate material 34 placed in the planar area 25 and allowed to slide down to the lower side, leaving at least a portion of the magnetic powder along the magnet 36 (Step C). The magnetic powder remaining on the plate material 34 is analyzed (Step D).

Description

Technical Field

[0001] The present invention relates to an analysis method. More specifically, it relates to a method for analyzing magnetic powder contained in greases such as lubricants. The present invention also relates to an equipment diagnosis method and a ferrography device.

Background Art

[0002] Lubricants such as lubricating oils and lubricating greases are widely used in sliding parts of various devices. In the sliding part of a device, since there is contact between the members constituting the sliding part, the members wear and wear powder derived from the members is generated. The generated wear powder mixes into the lubricant used in the sliding part. By analyzing the wear powder mixed in the lubricant, the wear state of the sliding part can be estimated.

[0003] As a member constituting the sliding part, a member containing iron, which is a magnetic material, may be used. As a method for analyzing wear powder (magnetic powder) generated from a member containing iron, the ferrography method has been conventionally known (see Patent Document 1).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] The ferrography method is a method of preparing a sample solution containing magnetic powder and collecting and analyzing the magnetic powder while separating it by magnetic force. However, the analysis using the device used in the conventional ferrography method lacks portability.

[0006] This invention has been made in view of the above points, and aims to provide an analytical method that can easily analyze magnetic powder. [Means for solving the problem]

[0007] As a result of diligent research, the inventors of this invention discovered that the above objective can be achieved by adopting the following configuration, and thus completed the present invention. In other words, the present invention provides the following [1] to [7]. [1] A ferrography apparatus comprising: step A, preparing a mixture of oil containing magnetic powder and a solvent as a sample solution; step B, preparing a ferrography apparatus comprising: a long plate material onto which the sample solution is dropped; a substrate having a long planar region on which the plate material is placed; a long magnet embedded in the planar region; and a holding mechanism that holds the substrate in an inclined state with one end of the magnet higher than the other end; step C, holding the substrate in the inclined state, dropping the sample solution onto the higher side of the plate material placed in the planar region and allowing it to slide down to the lower side, thereby leaving at least a portion of the magnetic powder along the magnet; and step D, analyzing the magnetic powder remaining on the plate material. [2] The analytical method according to [1] above, wherein the above mixture is stirred to prepare the above sample solution. [3] The analytical method according to [1] or [2] above, wherein the plate material is dried before analyzing the magnetic powder. [4] The analytical method according to any one of [1] to [3] above, wherein the substrate material is an absorbent material that can absorb the sample liquid. [5] The ferrography apparatus further comprises a stopper, the stopper restricting the plate material placed in the planar region from moving to the lower side when the base is held in the inclined state, according to any one of [1] to [4] above. [6] A method for diagnosing an instrument, comprising: collecting the above-mentioned oil and grease from the instrument; analyzing the magnetic powder contained in the collected oil and grease using the analytical method described in any of [1] to [5] above; and diagnosing the condition of the part of the instrument from which the oil and grease was collected based on the obtained analytical results. [7] A ferrography apparatus for analyzing magnetic powder, comprising: a long plate onto which a sample liquid, which is a mixture of oil and solvent containing magnetic powder, is dropped; a base having a long planar region on which the plate is placed; a long magnet embedded in the planar region; and a holding mechanism that holds the base in an inclined state with one end of the magnet higher than the other end. [Effects of the Invention]

[0008] According to the present invention, magnetic powder can be easily analyzed. [Brief explanation of the drawing]

[0009] [Figure 1] This is a cross-sectional view showing a container holding a sample solution. [Figure 2] This is a plan view showing a ferrography apparatus. [Figure 3] This is a cross-sectional view along line AA in Figure 2. [Figure 4] Figure 2 is a cross-sectional view along line BB. [Figure 5] This is a cross-sectional view showing a ferrography apparatus in which the substrate is held in an inclined position. [Figure 6] This is a schematic diagram showing an accumulation of magnetic powder remaining on the surface of a plate material. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described in detail below. However, the present invention is not limited to the embodiments described below. In this specification, numerical ranges represented using "~" mean a range that includes the numbers written before and after "~" as the lower and upper limits, respectively.

[0011] [Analytical methods, instrumental diagnostic methods, and ferrography equipment] The analytical method of this embodiment comprises at least steps A to D described later. This allows for the easy analysis of magnetic powder contained in oils and greases such as lubricants without using the equipment used in conventional ferrography methods. Hereinafter, the analysis method of the present embodiment will be described in more detail. The following description also serves as an explanation of the device diagnosis method and the ferrography apparatus.

[0012] 〈Step A〉 FIG. 1 is a cross-sectional view showing a container 20 containing a sample liquid 22. In Step A, a mixture of an oil and fat containing magnetic powder and a solvent is prepared as a sample liquid 22.

[0013] 《Magnetic Powder》 The magnetic powder preferably contains a magnetic material such as iron (Fe). The particles constituting the magnetic powder may be composite particles that partially contain non-magnetic materials such as copper alloy powder and oil degradation products in addition to a magnetic material such as Fe and are magnetically charged as a whole. In the composite particles, the magnetic material may be uniformly distributed throughout or may be unevenly distributed on the surface.

[0014] 《Oil and Fat》 Examples of the oil and fat containing magnetic powder include lubricants used in the sliding parts of devices. Specific examples of devices include hydraulic control devices, pumps, engines, pistons, bearings, gears, valves, etc., and bearings or gears are preferred. Specific examples of lubricants include lubricating greases, lubricating oils, etc. The lubricant can be collected from, for example, the sliding parts of the device. The collection amount can be adjusted as appropriate, but for example, 3 to 100 mL is preferred.

[0015] 《Solvent》 The solvent is not particularly limited, but a solvent that is miscible with components other than the magnetic powder in the oil and fat containing magnetic powder is preferred. As long as the oil and fat can be diluted with the solvent regardless of the mixing amount of the magnetic powder contained in the oil and fat, the magnetic powder can be analyzed. Examples of the solvent include hydrocarbon solvents, alcohol solvents, ether solvents, ester solvents, ketone solvents, etc., which can be appropriately selected, and may be used alone or in combination of two or more. Examples of hydrocarbon solvents include pentane, hexane, cyclohexane, benzene, heptane, toluene, octane, xylene, nonane, decane, and undecane. Examples of alcoholic solvents include methanol, ethanol, propanol, isopropyl alcohol, heptanol, hexanol, and octanol. Examples of ether-based solvents include dimethyl ether, ethyl methyl ether, diethyl ether, tetrahydrofuran, and furan. Examples of ester solvents include methyl acetate, ethyl acetate, γ-butyrolactone, propyl acetate, butyl acetate, ethyl acetate, and pentyl acetate. Examples of ketone solvents include acetone, methyl ethyl ketone, diethyl ketone, and cyclohexanone.

[0016] Sample solution Sample solution 22 is prepared as a mixture of oil containing magnetic powder and a solvent. The sample solution 22 may be prepared in the container 20 described later, or it may be prepared in a separate container from container 20 and then placed in container 20.

[0017] The amount of oil containing magnetic powder in sample solution 22 can be adjusted as appropriate. The content of oil containing magnetic powder in sample solution 22 is preferably 0.01 to 1.00% by mass, more preferably 0.05 to 0.50% by mass, and even more preferably 0.10 to 0.20% by mass. The ratio of oil containing magnetic powder to the solvent is preferably 0.1 to 10.0% by mass, more preferably 0.5 to 5.0% by mass, and even more preferably 1.0 to 2.0% by mass.

[0018] The amount of magnetic powder contained in the oil and fat may be quantified beforehand, and then the sample solution 22 may be prepared. Known methods can be used to measure the magnetic powder content in oils and fats. For example, a method can be used in which a certain amount of oil or fat is measured, diluted to a predetermined concentration to make a measurement solution, and quantitative ferrography is performed using the measurement solution. The magnetic powder content may also be measured using a particle counter or the like in relation to the measurement wave. The magnetic powder content in oils and fats may be measured using a grease iron powder concentration meter, an oil iron powder concentration meter, or the like. This allows for the measurement of magnetic powders across a wider particle size range.

[0019] Stirring When preparing the sample solution 22, it is preferable to stir the mixture of oil containing magnetic powder and the solvent in order to separate the magnetic powder from the oil. Known methods for stirring a mixture include methods of convection using a stirring rod or the like; methods of agitating a container containing the mixture; methods of applying shear force to the mixture using a rotating blade; and methods of irradiating the mixture with ultrasonic waves. Furthermore, if the oil is lubricating grease (especially lubricating grease containing water), it is preferable to stir it until any clumps of lubricating grease completely disappear.

[0020] "container" The sample solution 22 is contained in, for example, a conventionally known container 20. The material for the container 20 is preferably a material that does not dissolve in the solvent mentioned above, such as glass or resin (polyethylene terephthalate, polycarbonate, etc.). The container 20 is preferably transparent because it makes it easier to observe the dispersion state of the magnetic powder in the sample liquid 22. The shape of the container 20 is not particularly limited, but for example, it may be cylindrical. The volume of container 20 is not particularly limited, but is, for example, 1 to 100 mL, and preferably 8 to 30 mL. Specific examples of container 20 include glass or resin test tubes.

[0021] <Process B> Figure 2 is a plan view of the ferrography apparatus 50, Figure 3 is a cross-sectional view of Figure 2 along line AA, and Figure 4 is a cross-sectional view of Figure 2 along line BB. In step B, the ferrography apparatus 50 is prepared.

[0022] 《Plate material》 As shown in Figures 2 to 4, the ferrography apparatus 50 is equipped with a long plate material 34. The shape of the pair of main surfaces of the plate material 34 (the surface on which the sample liquid 22 is dropped, and the surface in contact with the planar area 25 of the base body 24, which will be described later) is preferably rectangular. The size of the plate material 34 is not particularly limited, but a thickness of 0.1 to 1.0 mm, a width of 20 to 30 mm, and a length of 50 to 75 mm are preferred. As will be described later, the sample liquid 22 is dripped onto the plate material 34 from the container 20. Therefore, the material of the plate material 34 is preferably a material that does not dissolve in the solvent of the sample solution 22, such as glass or resin (polyethylene terephthalate, polycarbonate, etc.). The plate material 34 may also be, for example, resin-coated paper. The plate material 34 is preferably white or transparent so that the dropped sample liquid 22 can be easily observed.

[0023] 《Base》 As shown in Figures 2 to 4, the ferrography apparatus 50 includes a substrate 24. The shape of the base 24 may be, for example, a rectangular parallelepiped (thick plate) having a pair of rectangular (square or rectangular) main faces. The thickness of the base 24 is, for example, 15 to 30 mm. The base body 24 has a long planar area 25 on which the plate material 34 is placed as part of its main surface. The size of the main surface of the base body 24 does not need to be larger than the planar area 25; specifically, the length of the main surface in the longitudinal direction (the length of one side if the main surface is square) is, for example, 90 to 120 mm. The material for the substrate 24 is preferably a material that does not dissolve in the solvent of the sample solution 22, and examples include non-metallic stones, solidified earth powders, resins, plastics, and diatomaceous earth. The material of the base 24 is preferably an absorbent material that can absorb the sample liquid 22, and diatomaceous earth is more preferable. This allows the base 24 to absorb the sample liquid 22 even if it spills onto the base 24 after being dropped onto the plate material 34 placed in the planar area 25.

[0024] "magnet" As shown in Figures 2 to 4, the ferrography apparatus 50 is equipped with a long magnet 36. The shape of the magnet 36 is not particularly limited, but examples include a flat plate shape with a thickness of 0.5 to 1.5 mm, a width of 7 to 12 mm, and a length of 10 to 40 mm. The magnet 36 is embedded in the planar region 25 of the base body 24. More specifically, in this embodiment, a long groove 27 is provided inside the base body 24, on the lower side of the main surface constituting the planar region 25, along the longitudinal direction of the planar region 25, and the flat magnet 36 is housed in the long groove 27 with a portion of it (the side surface) exposed to the outside.

[0025] In this embodiment, the magnet 36 is housed in the elongated groove 27, sandwiched between a pair of steel plates 26. The steel plates 26 are, for example, silicon steel plates, with a thickness of, for example, 0.1 to 0.7 mm, and preferably the same width and length as the magnet 36.

[0026] 《Holding mechanism》 Figure 5 is a cross-sectional view showing a ferrography apparatus 50 in which the base body 24 is held in an inclined state. The inclined state is a condition in which one end of the magnet 36 (see Figure 4) embedded in the base body 24 is higher than the other end. Through holes extending through the thickness direction are provided at the four corners of the base body 24, and four threaded rods 30 are inserted into these through holes and secured by nuts 32. As shown in Figure 4, in this embodiment, of the four threaded rods 30, the two threaded rods 30 on one end side (left side in Figure 4) of the magnet 36 embedded in the base 24 are longer than the two threaded rods on the other end side (right side in Figure 4). Therefore, when the base 24 is placed on a flat mounting surface 55 using the four threaded rods 30 as support legs, the base 24 is held in an inclined state, as shown in Figure 5. In other words, the threaded rods 30 and nuts 32 constitute a holding mechanism that holds the base 24 in an inclined state. Using four threaded rods 30 of the same length, the length of each threaded rod 30 acting as a support leg may be varied depending on the position of the nut 32. The inclination angle (the angle of the main surface (e.g., the planar area 25) of the base 24 relative to the installation surface 55) is preferably 10 to 20°.

[0027] Stopper As shown in Figure 5, when the base 24 is held in an inclined state, the plate material 34 placed in the planar area 25 moves to the lower side (lower right side in Figure 5) due to gravity. Therefore, in this embodiment, a stopper 40 that restricts the downward movement of the plate material 34 is provided on one surface of the base body 24 (the surface having a planar area 25). The stopper 40 is a member that is fixed in position to the base body 24 by embedding or the like. The plate material 34 is prevented from moving further to a lower position (lower right side in Figure 5) by contacting the fixed stopper 40. Preferably, the longitudinal center position of the plate material 34, restricted by the stopper 40, is the longitudinal center position of the magnet 36.

[0028] Furthermore, the sample liquid 22 dropped onto the plate material 34 may not easily fall off the lower end of the plate material 34 due to surface tension. At this time, the presence of the stopper 40 also has the effect of allowing the sample liquid 22 to smoothly detach from the plate material 34 via the stopper 40 and be absorbed into the substrate 24.

[0029] <Process C> In step C, the substrate 24 is held in an inclined position, and the sample liquid 22 is dropped onto the upper surface of the plate material 34 placed in the planar area 25. The method for dropping the sample solution 22 can be any known method, such as repeatedly dropping it at a rate of about one drop per second using an instrument such as a dropper or syringe.

[0030] The dropped sample liquid 22 slides down the surface of the plate material 34 toward the lower side due to gravity. At this time, a magnet 36 is embedded in the planar area 25 where the plate material 34 is placed. Therefore, at least a portion of the magnetic powder contained in the sample liquid 22 remains on the surface of the plate material 34 along the magnet 36 during the sliding process. The remaining portion of the sample liquid 22 then slides down to the lower side of the plate material 34. By repeatedly dropping the sample liquid 22, an accumulation of residual magnetic powder appears on the surface of the plate material 34.

[0031] Figure 6 is a schematic diagram showing the accumulation of magnetic powder 10 remaining on the surface of the plate material 34. The magnetic powder 10 shown in Figure 6 is accumulated along the shape of a long magnet 36 (not shown in Figure 6). In Figure 6, large-diameter particles (e.g., particle size 10 μm or larger) are accumulated in the central part of the plate material 34, while small-diameter particles (e.g., particle size less than 10 μm) are accumulated on both sides. In this case, it is preferable that the particles constituting the magnetic powder 10 accumulate without overlapping each other, for the sake of easier observation. That is, it is preferable that they form a striped pattern along the magnetic field of the magnet 36. By the way, if the total amount of sample solution 22 dropped is too large, too much magnetic powder 10 will remain on the plate material 34, making it easier for the particles to overlap. For this reason, it is preferable that the total amount of sample solution 22 dropped is an amount that does not cause this overlapping.

[0032] <Process D> In process D, the magnetic powder (accumulation) remaining on the plate material 34 is analyzed. For the analysis of the magnetic powder, a microscope such as a digital microscope is used. This allows for magnified observation of the magnetic powder and provides information such as particle size (maximum particle size, most numerous particle size, etc.) and morphology.

[0033] The uppermost side of the plate material 34 tends to retain magnetic powder with relatively large particle sizes that are easily attracted to the magnet 36. Therefore, analysis (observation) can be performed on only the magnetic powder with large particle sizes. Magnetic powder with large particle sizes is easy to observe in terms of shape and surface properties, and can be analyzed in detail. While conventional ferrography methods have made it difficult to analyze magnetic powder with large particle sizes, this embodiment makes it easy to analyze magnetic powder with large particle sizes.

[0034] Incidentally, as described above, the magnetic powder contained in the sample liquid 22 dropped onto the plate material 34 remains on the surface of the plate material 34 along the magnet 36, and the remaining portion of the sample liquid 22 slides down to the lower side of the plate material 34. However, some of the remaining sample liquid 22 may not slide down to the lower side of the plate material 34, but may remain on the upper or middle side of the plate material 34. Therefore, it is preferable to dry the plate material 34 before analyzing the magnetic powder remaining on the plate material 34. The drying method is not particularly limited and natural drying is acceptable. The drying time is, for example, 45 to 90 seconds.

[0035] Before analyzing the magnetic powder remaining on the plate material 34, it is preferable to remove the plate material 34 from the planar area 25 of the substrate 24 using tweezers or the like.

[0036] When a non-combustible material is used as the material for the plate material 34, when analyzing the magnetic powder remaining on the plate material 34, the magnetic powder is heated together with the plate material 34, and the metal contained in the magnetic powder can be identified by the discoloration that occurs due to this heating.

[0037] <diagnosis> In this embodiment, the condition (e.g., wear state) of the part of the equipment from which the oil and grease were collected (e.g., a sliding part) is further diagnosed based on the obtained analysis results.

[0038] <Summary of effects> As described above, according to this embodiment, magnetic powder contained in oils and greases such as lubricants can be easily analyzed without using the equipment used in conventional ferrography methods.

[0039] In conventional ferrography methods, for example, a quantitative ferrography apparatus and an analytical ferrography apparatus are used as a pair. Both apparatuses are large-scale devices that use motors powered by a 100V power source to collect magnetic powder contained in the sample liquid using magnets while the sample liquid is flowing through it. In contrast, the ferrography apparatus 50 used in this embodiment does not require a power source and is small and lightweight, making it possible to easily perform analysis of magnetic powder.

[0040] Furthermore, as will be explained below, according to this embodiment, even engineers without extensive experience can easily analyze magnetic powder and diagnose equipment.

[0041] For example, in equipment such as speed reducers and speed increasers, lubricating oil, which is a fluid, is used as the oil (lubricant). A certain amount of lubricating oil uniformly contains magnetic powder particles of a size of 1.0 to 30 μm that are easily suspended. To analyze the magnetic powder contained in such lubricating oil, for example, approximately 1.0 mL of lubricating oil is taken and a sample solution is prepared by diluting it 5 to 50 times. That is, the magnetic powder in 0.2 to 0.02 mL of the sample solution is analyzed.

[0042] On the other hand, in the case of lubricating grease, which is solid or semi-solid, a certain amount of lubricating grease contains magnetic powder of various particle sizes in an uneven state. Furthermore, the amount of magnetic powder mixed into lubricating grease is greater than that in lubricating oil. To analyze the magnetic powder contained in such lubricating grease, for example, approximately 0.004 mL of lubricating grease is taken and a sample solution is prepared by diluting it 5 to 50 times. That is, the magnetic powder in 0.0008 to 0.00008 mL of the sample solution is analyzed.

[0043] Thus, although the state of magnetic powder contamination differs between lubricating oil and lubricating grease, conventionally, they have been analyzed using the same method (apparatus). Currently, the mainstream analytical ferrography equipment is primarily used to analyze magnetic powder contained in lubricating oil. Therefore, for example, when using such equipment to analyze magnetic powder contained in lubricating grease, it can be difficult to detect some of the magnetic powder, resulting in a significant reduction in the amount of information (analysis results) obtained. As a result, a situation has been created where only certain engineers with extensive experience can perform the analysis.

[0044] In contrast, according to this embodiment, even when analyzing magnetic powder contained in lubricating grease, the amount of lubricating grease sampled is not particularly limited and can be any amount. Furthermore, in this embodiment, a lubricating grease diluted to approximately 2 to 5 times its original volume (sample solution 22) is dispensed dropwise using a dropper or the like, while adjusting the amount dispensed. This allows the magnetic powder to be collected according to the proportion of each particle size, even if the particle size of the magnetic powder mixed in a given amount of grease is not uniform but varies, thus greatly increasing the amount of information (analysis results) obtained from the magnetic powder. As a result, the condition of equipment such as bearings (degree of damage, type of damage, etc.) can be easily estimated and diagnosed. In other words, analysis and diagnosis can be easily performed even by engineers without extensive experience. [Examples]

[0045] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the examples described below.

[0046] The analysis was performed using the ferrography apparatus 50 described in Figures 2 to 5. More specifically, a resin test tube (11 mm inner diameter, 12.5 mm outer diameter, 100 mm length) was first prepared as a container 20 (see Figure 1) for holding the sample solution 22.

[0047] In addition, a glass plate 34 (0.3 mm thick, 25 mm wide, 60 mm long) was prepared for dropping the sample liquid 22. A diatomaceous earth base 24 (17 mm thick, with a square main surface and a side length of 100 mm) was prepared on which the plate 34 would be placed. A plate-shaped magnet 36 (1.0 mm thick, 10 mm wide, 20 mm long) and two steel plates 26 (0.3 mm thick, 10 mm long, 40 mm wide) were prepared to be embedded in the base 24. Other items such as a threaded rod 30 and a nut 32 were also prepared. Using the prepared parts, a ferrography apparatus 50 was fabricated, and the base 24 was held in an inclined position (inclination angle 15°).

[0048] Next, lubricating grease for analysis was collected from the rolling bearing and placed into container 20 using a spatula. Furthermore, 5 mL of commercially available penetrant degreasing and cleaning solution (heptane) was added as a solvent, and the mixture was stirred with a stirring rod until no clumps of lubricating grease were visible. In this way, sample solution 22 was prepared.

[0049] The sample liquid 22 was drawn up with a dropper and dropped onto the upper side of the plate material 34, which was placed in the planar area 25 of the substrate 24, at a rate of approximately 1 to 3 drops per second. By repeating the dropping process, an accumulation of magnetic powder appeared on the surface of the plate material 34. The total amount of droppings was set to the amount that would create a clear striped pattern in the accumulation. After the dripping was complete, a small amount of sample liquid 22 remained on the surface of the plate material 34, so it was left to air dry for about 60 seconds. Subsequently, the plate material 34 was removed from the base material 24 using tweezers, and the accumulation of magnetic powder on the surface of the plate material 34 was observed and analyzed using an optical microscope.

[0050] For the optical microscope, a digital microscope (Keyence Corporation, VHX-7000 (lens: VHX-E500)) was used, with observation magnifications of 500x and 1500x. For observation, the plate material 34 was set in the digital microscope with the vertical direction of the field of view perpendicular to the longitudinal direction of the plate material 34.

[0051] The observed magnetic powders can be classified into the following particles, for example: • Severe abrasion particles: Some particles are less than 5 μm in size, but those larger than 5 μm have surface streaks, directional wrinkles, and adhesion of fine particles, and may also have a temper color. The overall shape is that of a shape produced by plastic deformation, with the periphery being machined. • Fine abrasion particles: These particles have a diameter of approximately 1 μm and align in a sand-like pattern along the magnetic flux. They may also form aggregates larger than 5 μm. • Non-ferrous metal wear particles: These originate from copper alloys, tin alloys, etc. Due to contact wear with iron, iron particles adhere to or weld to them, resulting in a weakly magnetized state.

[0052] Observation using an optical microscope yielded the following analytical results for the magnetic powder. The magnetic powder (accumulated material) consisted mainly of "severely abrasive particles" with a particle size of 30 μm or larger. Specifically, most of the magnetic powder had a brownish temper color due to frictional heat, indicating a slight rolling morphology. Therefore, it was suspected that sliding contact was occurring in the bearing. Other magnetic powders included "fine wear particles" with a particle size of approximately 1.0 μm and their aggregates, as well as very small amounts of "non-ferrous metal wear particles" of copper alloy. These were presumed to be caused by poor lubrication due to moisture contamination, resulting in continuous friction wear.

[0053] The analysis results indicated that the bearing had reached the end of its lifespan (however, continued use is possible with the implementation of life-extending measures and the development of a replacement plan, although this carries risks).

[0054] Furthermore, the analysis results suggested that the bearing underwent the following damage stages. First, during prolonged use under high load conditions, rainwater entered the bearing, reducing the lubricity of the bearing's outer ring pressure-bearing surface. Due to the effects of the rainwater, significant wear progressed, while "fine wear particles" (aggregates) were discharged. Furthermore, excessive wear caused unevenness in the raceway surface, leading to the formation of microcracks, which in turn resulted in peeling and flaking (the generation of "severe abrasion particles"). In addition, the rolling elements, due to their failure to rotate, revolved while sliding, leading to sliding wear on the flaking surface. The cage wear (generation of "non-ferrous metal wear particles," which are copper alloy) occurred because the outer ring portion of the pressure-receiving surface wore down significantly, putting pressure on the rolling elements, which in turn compressed the sliding surface of the cage.

[0055] In the above-described embodiment, magnetic powder contained in lubricating grease collected from a bearing was analyzed to diagnose the wear condition of the bearing. However, the invention is not limited to this, and oils such as lubricants can be collected from the sliding parts of other equipment, and the magnetic powder contained therein can be analyzed, as well as the wear condition of the equipment (sliding parts) can be diagnosed. [Explanation of Symbols]

[0056] 10:Magnetic powder 20: Container 22: Sample solution 24: Base 25: Planar area 26: Steel plate 27: Long groove 30: Screw rod (holding mechanism) 32: Nut (retaining mechanism) 34: Board material 36: Magnet 40: Stopper 50: Ferrography device 55: Installation surface

Claims

1. Step A involves preparing a mixture of oil containing magnetic powder and a solvent as a sample solution, Step B of preparing a ferrography apparatus comprising: a long plate material onto which the sample liquid is dropped; a base having a long planar region on which the plate material is placed; a long magnet embedded in the planar region; and a holding mechanism that holds the base in an inclined state with one end of the magnet higher than the other end; Step C involves holding the substrate in the inclined state, then dropping the sample liquid onto the higher side of the plate material placed in the planar region and allowing it to slide down to the lower side, thereby leaving at least a portion of the magnetic powder along the magnet. An analytical method comprising step D, which involves analyzing the magnetic powder remaining on the plate material.

2. The analytical method according to claim 1, wherein the mixture is stirred to prepare the sample solution.

3. The analytical method according to claim 1, wherein the plate material is dried before analyzing the magnetic powder.

4. The analytical method according to claim 1, wherein the material of the substrate is an absorbent material that can absorb the sample liquid.

5. The ferrography apparatus further includes a stopper, The analysis method according to claim 1, wherein the stopper restricts the plate material positioned in the planar region from moving to a lower position when the base is held in the inclined state.

6. The oil and grease are collected from the equipment, The magnetic powder contained in the collected oil is analyzed by the analytical method described in any one of claims 1 to 5. A diagnostic method for an instrument, which diagnoses the condition of the part of the instrument from which the oil and grease was collected, based on the obtained analysis results.

7. A long plate material onto which a sample solution, which is a mixture of oil and solvent containing magnetic powder, is dropped, A base having a long planar region on which the plate material is arranged, A long magnet embedded in the aforementioned planar region, A ferrography apparatus for analyzing magnetic powder, comprising a holding mechanism that holds the substrate in an inclined state with one end of the magnet positioned higher than the other end.

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