DE10157316A1 - Hip replacement joint comprises ball and socket, surface of ball being etched to roughen it by forming microstructure of grooves - Google Patents

Abstract

Hip replacement joint comprises a ball (2) and socket (3). The surface (4) of the ball is etched to roughen it by forming a microstructure of grooves. Independent claims are included for: (a) a composite surface for a joint comprising an etched, roughened surface as above with a coating over it; and (b) a method for making the joint, as described above.

Description

The present invention relates to a bearing according to the preamble of Claim 1, use of an at least partially nanoscopic rough storage area according to the preamble of claim 15 or 18 and a method for manufacturing a bearing according to the preamble of Claim 20.

In the case of a bearing with a bearing surface, in particular a plain bearing a long service life with low friction is desirable. Become frequent Storage surfaces made of metal, ceramic or plastic are used.

Particle formation is particularly problematic a plain bearing to an undesirable so-called three-body abrasion (Bearing surface / particles / counter bearing surface). In particular, this can in an undesirable formation of scratches, grooves or the like in the Bearing surface and the counter bearing surface with the consequence of a reduction in the service life result. Furthermore, this can lead to undesired stiffness or Lead to increased friction.

The present invention has for its object a bearing Use of a storage surface that is at least partially nanoscopic rough and to provide a method of manufacturing a bearing so that the Wear or abrasion can be minimized or at least reduced that the Particle formation or at least the escape of particles can be reduced and / or that the friction can be reduced, in particular where the Service life of the storage area can be extended.

The above object is achieved by a bearing according to claim 1, a Use according to claim 15 or 18 or a method according to claim 20 solved. Advantageous further developments are the subject of the dependent claims.

A basic idea of the present invention is that Storage area at least in some areas, preferably at least in the entire support or load area to be nano-rough.

"Nanoscopic rough" is such a rough one here - preferably right down to the Microscopic (µm range) - surface formation understand that particles, preferably up to 1 µm or even up to 10 µm, at least partially absorbed by depressions in the surface and can be stored in particular. In particular, at least Particles up to 100 nm or 10 nm in the rough surface can be included.

The nanoscopically rough design of the storage area leads to several advantages:
First, particles that form can be taken up in depressions and in particular permanently stored there. This applies in particular to very fine or micro-particles, which arise primarily when two surfaces slide on each other. The three-body abrasion can thus be effectively reduced or even minimized.
Second, the nanoscopically rough bearing surface can more easily adapt to an assigned counter bearing surface. This is made possible in particular by plastic deformation or flattening of the micro hills. In this way, the bearing, which is preferably designed as a plain bearing or a joint, "runs in" faster.
Third, the depressions of the nanoscopically rough bearing surface form a lubricant reservoir. This helps to reduce friction and / or increase tool life.
Fourthly, the surface area of the nanoscopic rough surface is significantly enlarged compared to a smooth surface. The enlarged surface can bind or hold particles and / or lubricants better. This in turn is conducive to a reduction in friction and / or a reduction in tool life, in particular by reducing the three-body abrasion caused by free particles.

Preferably, the nanoscopically rough bearing surface is at least for the most part in particular, macroscopically smooth. For the To the human eye, the bearing surface appears smooth, even if there is discoloration or optical effects a color-varying appearance of the bearing surface can effect.

Other goals, advantages, characteristics and features of the present Invention emerge from the following description with reference to a preferred embodiment shown in the drawing. It shows:

Figure 1 is a schematic representation of a proposed bearing with an at least partially nanoscopic rough bearing surface.

FIG. 2 shows a schematic, partially enlarged sectional view of the bearing surface, neglecting the curvature of the bearing surface present in the embodiment according to FIG. 1;

Fig. 3 shows an enlarged detail of FIG. 2.

Fig. 1 shows a schematic representation of a proposed bearing 1 , which is designed as a plain bearing in the illustrated example. However, it can also be another bearing, such as a roller or roller bearing.

The illustrated bearing 1 has a bearing head 2 and an associated bearing shell 3 which, for reasons of illustration, are shown in a state apart from one another in FIG. 1. To illustrate, the bearing shell 3 is also shown in section.

Instead of being designed as a bearing head 2 and bearing shell 3 , the bearing elements which are assigned to one another can also have another shape which is adapted to the particular intended use. In particular, sliding and / or rolling storage can be provided.

In the depicted example, the bearing 1 or its bearing head 2 has a preferably metallic bearing surface 4 , which is made nanoscopically rough at least in an area 5 , in particular at least in the entire rolling or supporting area. The nanoscopically rough area 5 is shown in dotted lines in FIG. 1 for illustration.

In fact, the roughening of the bearing surface 4 in the area 5 or in the entire bearing surface 4 is so nanoscopically fine that the bearing surface 4 appears optically smooth to the human eye, even if the roughening results in an irregularly colored appearance of the bearing surface 4 in the nanoscopically rough region 5 leads.

The bearing 1 is made of a suitable material or several materials, such as metal, ceramic, plastic, composite material or the like.

The bearing surface 4 is preferably formed from a tough or ductile material. In particular, the bearing surface 4 is formed from plastic, ceramic or metal, preferably from steel, iron, titanium, chromium, an alloy based on iron, titanium or chromium and / or a cobalt-chromium alloy.

Fig. 2 is an enlarged, fragmentary sectional view of the bearing surface 4, with a subsequent surface layer 6 of the bearing head 2, the macroscopic curvature of the bearing surface 4 in the illustrated embodiment, is omitted so the ball head or kalottenaratige design of the bearing surface 4 for ease of illustration. Instead, the bearing surface 4 is shown macroscopically flat in FIG. 2.

The nanoscopically rough bearing surface 4 is provided with a multiplicity of depressions 7 and elevations 8 for its nanostructuring, which merge into one another or alternate with one another. In particular, the depressions 7 and elevations 8 merge into one another such that at least essentially no flat surface sections are formed between them.

The actual surface 9 of nanoscopically rough bearing surface 4 is accordingly significantly greater than that mediated by the macroscopically smooth contour 10 macroscopic area of extent of the bearing surface. 4 In the example shown, the surface 9 is preferably at least 2 times, in particular at least 2.5 times or 3 times, the macroscopic extension area of the bearing surface 4 .

The macroscopically smooth contour 10 , which is only indicated on the right-hand side in FIG. 2, can be regarded as the desired profile desired in a macroscopically usual, for example machining or grinding, which is preferably macroscopically smooth. The contour 10 in the illustration according to FIG. 2 for the explanation or definition of the average roughness R _{a is} not drawn on the elevations 8 , but between the elevations 8 and the depressions 7 . The mean roughness R _a namely represents the mean deviation of the elevations 8 and depressions 7 from the mean, macroscopically smooth nominal surface or contour 10 , as indicated in FIG. 2.

The two dashed lines on the right side of FIG. 2 indicate the height deviations of the depressions 7 and the elevations 8 from the middle, macroscopically smooth contour 10 . The specified average roughness R _a is determined from these deviations.

The average roughness R _{a of} the bearing surface 4 in the nanoscopically rough region 5 is at least 1 nm, in particular at least 10 nm or 100 nm, and / or at most 10 μm, in particular up to 2 or 1 μm.

The roughness depth R _T , ie the maximum height difference between one of the elevations 8 and one of the depressions 7 in the nanoscopically rough region 5 , is preferably at most 10 μm, in particular up to 2 or 1 μm.

The average diameter D of the depressions 7 is preferably at least 10 nm, in particular at least 50 nm or 100 nm and / or preferably at most 10 μm, in particular up to at most 3 or 1 μm. A diameter D of 200 to 500 nm is very particularly preferred.

The elevations 8 and the depressions 7 are in particular very irregularly formed, as indicated schematically in FIG. 2. Preferably, the elevations 8 and depressions 7 are in turn structured or rough on their surface, as shown by the partial schematic enlargement according to FIG. Fig. 3 indicated.

However, a regular or at least substantially uniform formation of the depressions 7 and / or the elevations 8 is in principle also possible.

Despite the irregularity mentioned, profiling or structuring in the nanometer range, ie in particular with structure widths of less than 1000 nm, in particular less than 500 nm, can be referred to in the case of the nanoscopically rough bearing surface 4 . The structural width here denotes the extent to which individual structural elements, such as the depressions 7 and elevations 8 , are repeated, that is to say, for example, the center distance between mutually adjacent elevations 8 or depressions 7 adjacent to one another.

The depressions 7 or elevations 8 are preferably arranged irregularly distributed over the bearing surface 4 at least in the nanoscopically rough region 5 , the adjacent depressions 7 being separated from one another by preferably also irregularly shaped elevations 8 . In principle, however, an at least substantially uniform distribution of the depressions 7 or the elevations 8 on the bearing surface 4 is also possible.

The mean surface density of the depressions 7 or elevations 8 is preferably at least 1.10 ⁵ / mm ² , in particular at least 2.10 ⁵ / mm ² or 5.10 ⁵ / mm ² .

The bearing surface 4 is assigned a counter bearing surface 11 , which is formed on the bearing shell 3 in the illustrated example, as indicated in FIG. 1. The counter bearing surface 11 is complementary to the bearing surface 4 in the example shown. However, depending on the intended use and the bearing structure, the counter bearing surface 11 can also have a shape that deviates from the complementary surface shape. This applies in particular to other plain bearings or roller or roller bearings.

In the example shown, the bearing surface 4 and the counter bearing surface 11 slide on one another, thus forming a plain bearing. However, rolling movements can also be superimposed on the sliding movement. As already mentioned above, other types of bearings can in principle also be realized, for example with a flat bearing surface 4 and / or counter-bearing surface 11 or with a primary rolling movement.

The counter bearing surface 11 is preferably at least substantially smooth, that is to say preferably both macroscopically smooth and also nanoscopically smooth (ie, not nanoscopically rough).

If necessary, the counter bearing surface 11 can also be made nanoscopically rough at least in some areas. According to one embodiment variant, the counter bearing surface 11 is provided with fine pores or cavities that are open to the outside, for example with an average diameter of 100 to 1000 nm. In particular, I formed the counter bearing surface 11 by an oxide layer from a so-called valve metal (formation of the pores or cavities by anodization), preferably aluminum oxide. The pores or cavities can then take up additionally formed particles and / or serve as a lubricant reservoir.

The counter bearing surface 11 is formed from a suitable material, such as plastic, ceramic or metal. The counter bearing surface 11 is preferably harder than the bearing surface 4 or its nanoscopically rough region 5 , in order to achieve the desired absorption of particles that are formed in the recesses 7 of the bearing surface 4 . In particular, the counter bearing surface 11 is formed from silicon dioxide or aluminum oxide. For example, the counter bearing surface 11 can also be formed from the same or a similar material as the bearing surface 4 .

In the example shown, the bearing surface 4 , which is rough at least in some areas nanoscopic, is formed on the bearing head 2 and the counter bearing surface 11 on the bearing shell 3 . However, this can also be the other way round.

Depending on the application, the bearing surface 4 and the counter bearing surface 11 can slide directly onto one another, that is to say if necessary form a lubricant-free bearing. A lubricant 12 is preferably assigned to the bearing surface 4, at least in the nanoscopically rough region 5 , as indicated in FIG. 1.

The proposed bearing 1 is preferably used such that the surface pressure of the bearing surface 4 or its area 5 is at most 100 MPa, in particular at most 50 MPa or 20 MPa. This applies in particular to the metallic design of the bearing surface 4 , but also depends on the material used.

The proposed nanoscopic rough design of the bearing surface 4 , in particular in combination with a preferably at least substantially smooth and / or harder counter bearing surface 11 , enables a very rapid running-in with little particle formation or at least little particle separation. In addition, there is relatively little friction. This can be explained by the fact that in the running-in phase there is a rapid adaptation of the bearing surface 4 , which is preferably formed from a tough and / or ductile material, in particular metal, to the counter-bearing surface 11 , resulting particles which otherwise lead to the undesirable three-body abrasion can lead, can be received by the recesses 7 of the bearing surface 4 . In addition, the lubricant 12 adheres particularly well to the large surface 9 of the bearing surface 4 , a relatively large lubricant reservoir also being formed in the recesses 7 , so that low friction, in particular sliding friction, is made possible.

Tests have also shown that a further advantageous effect can occur in the proposed solution. In particular in the case of metallic bearing surfaces 4 , the resulting metal particles - at least in some areas - can form a very solid particle layer of, for example, approximately 10 nm thick on the elevations or micro hills 8 . The particle layer that forms can bond very well to the bearing surface 4 due to the depressions 7 . A high strength of the particle layer can result in particular in that the individual metal particles, due to their small size, oxidize at least partially, in particular at least largely completely. A particularly hard oxide layer is then formed from the particles, which is accordingly very wear-resistant or abrasion-resistant.

A particularly preferred surface shape of the bearing surface 4 is obtained by etching the bearing surface 4 , in particular using sulfuric acid and / or chromosulfuric acid. In addition, this allows simple manufacture. For example, the metallic bearing surface 4 , in particular made of stainless iron or steel or a cobalt-chromium alloy, is exposed to the heated acid. When the acid is heated to approximately 200 ° C., approximately a molar concentration, an exposure time of 30 minutes to 2 hours is sufficient. Accordingly, wet-chemical treatment or roughening of the bearing surface 4 can take place.

As an alternative or in addition, electrochemical support or promotion of the etching process can also take place. For example, about 30 ° C. to 70 ° C., preferably about 40 ° C. warm acid is then sufficient to etch the bearing surface 4 appropriately with a comparable exposure time, that is to say to partially remove it with the formation of the depressions 7 .

A mechanical treatment or roughening of the bearing surface 4 to form the nanoscopically rough region 5 can take place, for example, by embossing, engraving or laser processing. Casting or molding for mechanical formation of the nanoscopically rough bearing surface 4 is also possible.

There will be a bearing, a use of at least some areas nanoscopic rough storage area and a method for producing a Bearing proposed with a nanoscopically rough storage area. A Improvement of storage properties - minimization of particle formation and Reduction of friction - is achieved in that the bearing surface at least is roughly formed nanoscopically in some areas. This is particularly the case by etching the storage area.

Claims (24)

1. Bearing ( 1 ), in particular plain bearing, with a bearing surface ( 4 ), characterized in that the bearing surface ( 4 ) is at least partially nanoscopic rough. 2. Bearing according to claim 1, characterized in that the bearing surface ( 4 ) is at least largely nanoscopic rough. 3. Bearing according to claim 1 or 2, characterized in that the bearing surface ( 4 ) is at least partially, in particular at least largely, macroscopically smooth, in particular in nanoscopically rough areas ( 5 ). 4. Bearing according to one of the preceding claims, characterized in that the bearing surface ( 4 ) is formed from a tough material. 5. Bearing according to one of the preceding claims, characterized in that the bearing surface ( 4 ) made of plastic, ceramic or metal, in particular steel, iron, titanium, chromium, an alloy based on iron, titanium or chromium and / or a cobalt Chrome alloy, is formed. 6. Bearing according to one of the preceding claims, characterized in that the bearing surface ( 4 ) at least in regions nanoscopically rough with an average roughness (R _a ) of at least 1 nm, in particular at least 10 nm or 100 nm, and / or at most 10 µm , in particular up to 5 microns or 2 microns, is formed. 7. Bearing according to one of the preceding claims, characterized in that the bearing surface ( 4 ) is at least partially nanoscopic rough with a roughness (R _T ) of at most 10 microns, in particular up to 5 microns or 2 microns, is formed. 8. Bearing according to one of the preceding claims, characterized in that the bearing surface ( 4 ) is at least partially nanoscopic rough with recesses ( 7 ), between which at least substantially no flat surface sections are present. 9. Bearing according to one of the preceding claims, characterized in that the bearing surface ( 4 ) is at least partially nanoscopically rough with depressions ( 7 ) whose average diameter (D) is at least 10 nm, in particular at least 50 nm or 100 nm, and / or at most 10 µm, in particular at most 2 µm or 1 µm. 10. Bearing according to one of the preceding claims, characterized in that the bearing surface ( 4 ) at least in regions nanoscopically rough with depressions ( 7 ) with a surface density of at least 1.10 ⁵ / mm ² , in particular at least 2.10 ⁵ / mm ² or 5.10 ⁵ / mm ² , is formed. 11. Bearing according to one of the preceding claims, characterized in that the bearing surface ( 4 ) is at least partially so nanoscopically rough that its surface ( 9 ) at least twice, in particular at least 2.5 times or 3 times , the macroscopic extension area of the nanoscopic rough area ( 5 ). 12. Bearing according to one of the preceding claims, characterized in that the at least partially nanoscopically rough bearing surface ( 4 ) is assigned a counter bearing surface ( 11 ) which is in particular nanoscopically smooth. 13. Bearing according to claim 12, characterized in that the counter bearing surface ( 11 ) made of metal, ceramic or plastic and / or harder than the bearing surface ( 4 ). 14. Bearing according to claim 12 or 13, characterized in that the bearing surface ( 4 ) and the counter bearing surface ( 11 ) slide on one another and / or roll. 15. Use of an at least partially nanoscopic rough bearing surface ( 4 ) to reduce particle formation or release and / or to reduce friction in a bearing ( 1 ), characterized in that the bearing surface ( 4 ) on an at least substantially smooth and / or harder counter bearing surface ( 11 ) slides and / or that a lubricant ( 12 ) is applied to the bearing surface ( 4 ). 16. Use according to claim 15, characterized in that the bearing surface ( 4 ) is designed according to the characterizing feature of one of claims 1 to 11. 17. Use according to claim 1 S or 16, characterized in that the counter bearing surface ( 11 ) is formed from metal, ceramic or plastic. 18. Use of an at least partially nanoscopic rough bearing surface ( 4 ) to reduce particle formation or release and / or to reduce friction in a bearing ( 1 ), in particular according to one of claims 15 to 17, characterized in that the bearing surface ( 4 ) is loaded with an average macroscopic surface pressure of at most 100 MPa. 19. Use according to claim 18, characterized in that the middle Macroscopic surface load at most 50 MPa, in particular at most 20 MPa. 20. A method for producing a bearing ( 1 ) with a nanoscopically rough bearing surface ( 4 ), characterized in that the bearing surface ( 4 ) is roughened mechanically, wet-chemically and / or electrochemically. 21. The method according to claim 20, characterized in that the bearing surface ( 4 ) consists of metal, ceramic or plastic. 22. The method according to claim 20 or 21, characterized in that the roughening is carried out by etching the bearing surface ( 4 ). 23. The method according to any one of claims 20 to 22, characterized in that that the roughening by the action of, in particular, heated acid, preferably of chromic sulfuric acid and / or sulfuric acid. 24. The method according to any one of claims 20 to 23, characterized in that the bearing surface ( 4 ) made of plastic, ceramic or metal, in particular steel, iron, titanium, chromium, an alloy based on iron, titanium or chromium and / or one Cobalt-chromium alloy.