阅读说明：本技术 多层烧结套管及轴承 (Multilayer sintered sleeve and bearing ) 是由 莱斯利·约翰·法辛 延斯·威尔曼 于 2018-04-13 设计创作，主要内容包括：提供了由不同合金形成的套管,所述不同合金被选择为适应不同的工作条件。例如,套管可以包括在套管的暴露于较低温度的部分中的铁基合金,以及在所述套管的暴露于较高温度的部分中的钴基合金。所述第一合金和所述第二合金可以轴向地或径向地对齐。所述铁基合金包括10-30wt.％的Cr,0-21wt.％的Ni,0-10wt.％的Mo,0-5wt.％的W,0-3wt.％的C,0-4wt.％的V,0-20wt.％的Co,余量为Fe。所述钴基合金包括10-30wt.％的Cr,5-21wt.％的Ni,0-10wt.％的Mo,0-10wt.％的W,0-3wt.％的V,0.5-3wt.％的C,余量为Co。(A sleeve formed of different alloys selected to accommodate different operating conditions is provided. For example, the sleeve may include an iron-based alloy in portions of the sleeve exposed to lower temperatures, and a cobalt-based alloy in portions of the sleeve exposed to higher temperatures. The first alloy and the second alloy may be axially or radially aligned. The iron-based alloy includes 10-30 wt.% Cr, 0-21 wt.% Ni, 0-10 wt.% Mo, 0-5 wt.% W, 0-3 wt.% C, 0-4 wt.% V, 0-20 wt.% Co, and the balance Fe. The cobalt-based alloy includes 10-30 wt.% Cr, 5-21 wt.% Ni, 0-10 wt.% Mo, 0-10 wt.% W, 0-3 wt.% V, 0.5-3 wt.% C, and the balance Co.)

1. A cannula, comprising:

a body extending axially along a longitudinal axis between opposite ends and radially from an outer surface to an inner surface,

the body comprises a first material and a second material different from the first material, an

The first material is a ferrous based material, wherein the ferrous based material comprises:

10-30 wt.% Cr, 0-21 wt.% Ni, 0-10 wt.% Mo, 0-5 wt.% W, 0-3 wt.% C, 0-4 wt.% V, 0-20 wt.% Co, and Fe, based on the total weight of the first material.

2. The cannula of claim 1, wherein the first material and the second material are radially or axially aligned.

3. The bushing of claim 1, wherein the second material is a cobalt-based material.

4. The cannula according to claim 3,

the cobalt-based material includes: 10-30 wt.% Cr, 5-21 wt.% Ni, 0-10 wt.% Mo, 0-10 wt.% W, 0-3 wt.% V, 0.5-3 wt.% C, and Co, based on the total weight of the cobalt-based material.

5. The cannula according to claim 3,

the cobalt-based material includes: 20-30 wt.% Cr, 5-15 wt.% Ni, 0-3 wt.% Mo, 5-10 wt.% W, 0-3 wt.% V, 0.5-2 wt.% C, and Co, based on the total weight of the cobalt-based material.

6. The cannula according to claim 3,

the cobalt-based material includes: 20-30 wt.% Cr, 5-15 wt.% Ni, 0-2 wt.% Mo, 5-10 wt.% W, 0-2 wt.% V, 0.5-1.5 wt.% C, and Co, based on the total weight of the cobalt-based material.

7. The cannula according to claim 3,

the cobalt-based material includes: 20-30 wt.% Cr, 5-15 wt.% Ni, 5-10 wt.% W, and 0.5-1.5 wt.% C, based on the total weight of the cobalt-based material; and is

The iron-based material includes: 10-20 wt.% Cr, 5-15 wt.% Ni, 1-5 wt.% Mo, and 1-2 w% C, based on the total weight of the iron-based material.

8. The bushing of claim 1 wherein the second material is an iron-based material different from the first material.

9. The cannula according to claim 1,

the first material comprises: 15-25 wt.% Cr, 0-5 wt.% Ni, 1.5-6.5 wt.% Mo, 1-4 wt.% W, 1-3 wt.% V, and 0.5-2.5 wt.% C, based on the total weight of the first material.

10. The cannula according to claim 1,

the first material comprises: 18-24 wt.% Cr, 0-5 wt.% Ni, 1.5-6.5 wt.% Mo, 1-4 wt.% W, 1-3 wt.% V, and 0.8-2.4 wt.% C, based on the total weight of the first material.

11. The cannula according to claim 1,

the first material comprises: 10-25 wt.% Cr, 7-20 wt.% Ni, 1-7 wt.% Mo, 0-3 wt.% W, 0-3 wt.% V, and 0.5-3 wt.% C, based on the total weight of the first material.

12. The cannula according to claim 1,

the first material comprises: 13-25 wt.% Cr, 7-20 wt.% Ni, 1-7 wt.% Mo, 0-2 wt.% W, 0-2 wt.% V, and 1-3 wt.% C, based on the total weight of the first material.

13. The cannula according to claim 1,

the first material comprises: 10-25 wt.% Cr, 10-21 wt.% Ni, 2-10 wt.% Mo, 0-3 wt.% W, 0-2 wt.% V, 4-20 wt.% Co, and 0.5-2 wt.% C, based on the total weight of the first material.

14. The cannula according to claim 1,

the first material comprises: 13-25 wt.% Cr, 10-21 wt.% Ni, 2-10 wt.% Mo, 0-3 wt.% W, 0-2 wt.% V, 4-20 wt.% Co, and 0.8-1.6 wt.% C, based on the total weight of the first material.

15. The cannula of claim 1, wherein the cannula has a tubular shape,

the second material is a cobalt-based material, which

Comprising 10-30 wt.% Cr, 5-21 wt.% Ni, 0-10 wt.% Mo, 0-10 wt.% W, 0-3 wt.% V, 0.5-3 wt.% C, and Co, based on the total weight of the first material;

the first material and the second material are sintered powder metal;

the second material has a different composition, microstructure, and/or properties than the first material; and

the first material has an axial length in the range of 5% to 95% of the total length of the cannula.

16. The cannula of claim 1, comprising a third material different from the first material and/or the second material.

17. The cannula of claim 16, wherein the first material and the third material are located at axial ends of the cannula; the second material is located between the first material and the third material; the first material and the third material are ferrous based materials including: 15-25 wt.% Cr, 2-5 wt.% Mo, 2-5 wt.% W, 1-3 wt.% V, and 1.5-2.5 wt.% C, based on the total weight of the ferrous material; and, the second material is a ferrous material including: 10-15 wt.% Cr and 0.5-15% C, based on the total weight of the second material.

18. A cannula, comprising:

a body extending axially along a longitudinal axis between opposite ends and radially from an outer surface to an inner surface,

the body comprises a first material and a second material different from the first material, an

The first material and the second material are radially aligned.

19. A turbocharger having a bore and comprising a sleeve disposed in the bore, the sleeve comprising a body extending axially along a longitudinal axis between opposite ends and radially from an outer surface to an inner surface,

the body includes a first material and a second material different from the first material, and

the first material is a ferrous based material comprising: 10-30 wt.% Cr, 0-21 wt.% Ni, 0-10 wt.% Mo, 0-5 wt.% W, 0-3 wt.% C, 0-4 wt.% V, 0-20 wt.% Co, and Fe, based on the total weight of the first material.

20. A method of manufacturing a bushing, comprising the steps of:

joining a first material to a second material different from the first material, the first material being a ferrous material comprising: 10-30 wt% Cr, 0-21 wt% Ni, 0-10 wt% Mo, 0-5 wt% W, 0-3 wt.% C, 0-4 wt.% V, 0-20 wt.% Co, and Fe, based on the total weight of the first material.

21. The method of claim 20, wherein the joining step comprises simultaneously pressing the first material and the second material to form a single pressed component, and sintering the single pressed component.

22. The method of claim 20, comprising separately pressing the first and second materials, and wherein the joining step comprises sinter brazing the pressed first and second materials.

23. The method of claim 20, comprising separately pressing the first and second materials, and wherein the joining step comprises sinter bonding.

24. The method of claim 20, comprising pressing and sintering the first and second materials, respectively, and wherein the joining step comprises friction welding the sintered materials.

25. A method of manufacturing a bushing, comprising the steps of: joining a first material to a second material different from the first material, wherein the second material is radially aligned with the first material.

Technical Field

The present invention generally relates to powder metal sintered bushings and bearings for high temperature applications (e.g., 250 ℃ and above).

Background of the invention

Disclosure of Invention

The present invention provides a sintered powder metal bearing or sleeve having at least a first region made of a first alloy material and a second region made of a second alloy material different from the first alloy material.

The sleeve or bearing extends circumferentially and axially. If a sleeve, it may be generally tubular, having a generally cylindrical outer surface and a generally tubular inner surface, and may extend axially between opposite ends. The first and second regions may be axially disposed relative to one another such that the first region may be near one end of the sleeve and the second region may be near an opposite end. The first end may represent the "hot" end of the sleeve, which is subjected to high temperatures, and the alloy for the hot end is selected to suit the high temperature environment. The second end may represent a "cold" end of the sleeve that is subjected to a lower temperature, and the alloy of the second region is different from the alloy of the first region and is more suitable for a cooled environment.

Other arrangements are possible, wherein there may be three or more regions arranged axially with respect to each other. For example, the sleeve or bearing may be subject to more wear or higher mechanical stress near the opposite axial ends and may be formed from a first alloy that performs well under these conditions, while a second region, axially between and spaced from the first region, may be formed. A second alloy, different from the second alloy, which is more suitable for a low wear or low stress environment of the bearing or bushing intermediate portion.

The present invention also contemplates radial variation, for example, a sleeve having a higher wear or temperature on its inner surface and a lower wear or temperature on its outer surface, such that the radially inner first zone layer is made of the first sintered powder metal alloy. The first sintered powder metal alloy performs well at high wear and/or elevated temperatures and the radially outer second region layer is made of a second sintered powder metal layer which is more suitable for lower temperatures and/or wear.

The present invention contemplates selecting an alloy for one of the zones as the high alloy iron and/or cobalt based material. High alloy preferably refers to an alloy content (by weight) with >10 wt.% of alloying elements. The alloy may include a formulation based on, for example, 410L stainless steel. The present invention also contemplates higher alloy additions, where the alloy content may exceed 25 wt.% or even 30 wt.%, for example based on a formulation of 316 stainless steel. The alloy of the other region may have a lower alloy content than the first material and may be adapted to the performance of the working environment (e.g., different working temperatures and/or different mechanical stresses) encountered by the region of the sleeve/bearing in use. Alternatively, the alloy of the other region may have a similar alloy content as the first material, but with a different combination of alloying elements to achieve properties better suited to the particular operating environment.

The present invention contemplates the manufacture of these multi-layer bearings/sleeves by a variety of possible manufacturing techniques. One method involves pressing different powders together (representing the alloy of the first and second regions) into a combined compact, followed by sintering. Alternatively, the first and second regions may be pressed separately and then bonded together during sintering in a process commonly referred to as sinter bonding. This bonding may also be facilitated by brazing the parts together through a special active layer in a process commonly referred to as "sinter brazing". Yet another method is to compact and sinter each of the first and second regions and then join them together by welding, such as friction welding.

The multilayer material according to the invention enables the designer of a bushing or bearing to select the best material for each local environment of the bushing or bearing using different alloy formulations formulated separately for the different local operating environments. For example, if a bushing for a particular application (e.g., a turbocharger) is susceptible to hot end wear at temperatures >700 ℃, the first end region may be made of a high alloy sintered powder material that should correspond to a material suitable for the conditions. In contrast, the opposite second end may be relatively cold, e.g. <400 ℃, so the end region may be made of a different high alloy sintered metal material formulated to provide good performance in the particular working environment. There may be an intermediate third region which may benefit from another alloy and which may be employed and bonded in situ or post-sintered to the first and second regions. In the case of a sleeve, these regions are preferably axial, but may also be radial depending on the application.

One aspect of the present invention provides a cannula including a body extending axially along a longitudinal axis between opposite ends and radially from an outer surface to an inner surface. The body includes a first material and a second material different from the first material. The first material is an iron-based material comprising 10-30 wt.% Cr, 0-21 wt.% Ni, 0-10 wt.% Mo, 0-5 wt.% W, 0-3 wt.% C, 0-4 wt.% V, 0-20 wt.% Co, and Fe, based on the total weight of the first material.

Another aspect of the invention provides a cannula including a body extending axially along a longitudinal axis between opposite ends and radially from an outer surface to an inner surface. The body includes a first material and a second material different from the first material, and the first material and the second material are radially aligned.

Yet another aspect of the present invention provides a turbocharger having a bore and including a bushing disposed in the bore.

Another aspect of the present invention provides a method of manufacturing a bushing. The method comprises the following steps: joining a first material to a second material different from the first material, the first material being an iron-based material comprising 10-30 wt.% Cr, 0-21 wt.% Ni, 0-10 wt.% Mo, 0-5 wt.% W, 0-3 wt.% C, 0-4 wt.% V, 0-20 wt.% Co, and Fe, based on the total weight of the first material.

Yet another aspect of the invention provides a method of manufacturing a cannula, the method comprising the step of joining a first material to a second material different from the first material, wherein the second material is radially aligned with the first material.

Brief description of the drawings

These and other features and advantages of the present invention will be readily understood when considered in connection with the following detailed description and the accompanying drawings, wherein:

FIG. 1 is a perspective view of a first embodiment of a multi-layer sleeve;

FIG. 2 is a perspective view of a second embodiment of a multi-layer sleeve;

FIG. 3 is a perspective view of a third embodiment of a multi-layer sleeve;

FIG. 4 is a cross-sectional view of the cannula of FIG. 1 taken along its longitudinal axis;

FIG. 5 is a cross-sectional view of the cannula of FIG. 2 taken along its longitudinal axis;

FIG. 6 is a cross-sectional view of the cannula of FIG. 3 taken along its longitudinal axis;

FIG. 7 is a schematic illustration of a turbocharger environment with a bushing installed, illustrating the extreme limits typically experienced by a bushing along its axial length;

FIG. 8 is a schematic cross-sectional view illustrating a casing installed in an environment where variable load and wear conditions are applied to the casing;

FIGS. 9a and 9b are perspective views of an alternative multi-layer bearing structure showing axial and radial layers, respectively;

FIG. 10 is a schematic view showing the multi-layer compaction of different powder metal alloy materials used to make the sleeve or bearing;

11a-11c are schematic diagrams illustrating sinter brazing of an axial multi-layer sleeve and bearing;

11d-11f are schematic diagrams illustrating a sintered bond of an axial multi-layer sleeve and a bearing, wherein no special brazing is added;

11 g-11 h are schematic diagrams illustrating profiles that may be used for easier alignment during assembly for sinter bonding or sinter brazing; and

12a-b are schematic diagrams illustrating friction welding of an axial multi-layer sleeve or bearing.

Description of The Preferred Embodiment

Fig. 1 and 4 illustrate a first embodiment of a sleeve 10, the sleeve 10 having a generally tubular shape with an outer surface 12 that is generally cylindrical and an inner surface 14 that is also generally cylindrical and spaced radially inward from the outer surface. The sleeve 10 extends axially along a longitudinal axis X between opposite ends 16, 18. It may be grooved in one or both ends 16, 18 or have other machined features on the end face and/or outer and/or inner diameter. The bushing 10 may be installed, for example, in a turbocharger 19 for an internal combustion engine as shown in fig. 7.

The sleeve 10 is made of sintered powder metal of at least two different alloy materials. The sleeve 10 has a first axial portion 20 and a second axial portion 22. The first axial portion is made of a first sintered metal alloy of material a and the second portion is made of a second sintered metal alloy of material B that differs in composition and/or properties from material a. The alloy of materials a and B is preferably an iron-based alloy and/or a cobalt-based alloy. The alloys of materials a and B of the sections 20, 22 will have different compositions and/or microstructures and may also be subjected to different processes (heat treatment, coating, surface finish, etc.) to produce different properties and may have the same or different lengths and the same or different thicknesses or inner or outer diameters. The different attributes may include: wear resistance, thermal and mechanical properties, oxidation and corrosion resistance, combinations of the above attributes, or others.

As shown in fig. 1 and 4, the portions 20, 22 of the sleeve 10 may have unequal lengths. The length of material a in the first portion 20 may be in the range of 5% -95% of the total length of the sleeve 10, with the balance being taken up by material B of the second portion 22. For example, material a may occupy about 25% of the total length of the sleeve 10, and material B may occupy 75% of the total length of the sleeve 10.

A sleeve 10 of the type shown in fig. 1 and 4 and described herein will be used in any application where different axial portions of the sleeve 10 are subjected to different conditions during use, and therefore it is preferred to use a sintered powder metal material having a set of properties best suited for a particular local environment in a given axial region, and to use a sintered powder metal material having different properties suited for other local environments in another axial portion of the bearing 10. One such example is a bushing for a turbocharger device in an internal combustion engine application. Fig. 7 shows a portion of the turbocharger 19 and shows the bushing 10 installed in the bore 24 of the turbocharger 19. The axial length of the sleeve 10 is 25 mm. The lower end of the sleeve 10 is exposed to the hot gases of the turbocharger environment and therefore, depending on the particular turbocharger, application and use, it is subjected to very high temperatures, from 500 ℃ to about 800 ℃. In contrast, the opposite upper end is insulated from intense heat and is subjected to temperatures in the range of 300 ℃ to 500 ℃. Thus, in a span of 25mm, the opposite end regions of the sleeve 10 experience a temperature difference of about 200 ℃ to 300 ℃. It should be understood that a powder metal sintered material suitable for a 300-500 c operating environment at a lower temperature region of the sleeve 10 will not necessarily have good performance at a higher temperature region of 500-800 c. In a typical design environment, an engineer would consider a number of factors, particularly the maximum temperature, and select a sintered metal material that is capable of meeting both environments. In other words, a compromise in material selection may have to be made in view of many local environmental factors and the associated performance of the candidate material. This compromise is substantially minimized using the multi-layer axial sleeve of fig. 1 and 4. Rather than selecting the best compromise material to meet all local environments, the lower temperature region is considered the first axial portion of the sleeve 10 and the higher temperature region is considered the second axial portion of the sleeve, and as in the present embodiment, in the manufacture of the dual material sleeve 10, the sintered powder metal material is individually selected as being most suitable for each particular environment. The material a for the first portion 20 is typically a different alloy than the material B for the second portion 22, but it is contemplated that these materials may even be of the same chemical composition, but their microstructures may differ substantially to produce different properties as desired, depending on the application involved. In this embodiment, a cobalt-based material may be selected for the "hot" regions of the sleeve 10 and an iron-based material may be selected for the "cold" regions of the sleeve 10. The cobalt-based material may include 20-30 wt% of Cr, 5-15 wt% of Ni, 5-10 wt% of W, and 0.5-1.5 wt% of C as main alloying elements. The iron-based material may contain 10-20 wt% of Cr, 5-15 wt% of Ni, 1-5 wt% of Mo and 1-2 w% of C as main alloying elements. The formula of the cobalt-based material can adapt to local high-temperature working environment, and different components of the iron-based material are suitable for local low-temperature working environment. Beneficial properties that make cobalt-based materials suitable for the hotter first axial portion include high temperature wear resistance as well as oxidation and corrosion resistance. The beneficial properties of making the ferrous material suitable for the cooler second axial section include good mechanical and thermal properties and sufficient wear resistance. It can be seen that the properties of the material required for the cooler regions may not be a desirable choice for the hotter regions, as the material may be subject to excessive oxidation or corrosion at high temperatures, and the high temperature wear resistance may also be insufficient, resulting in failure of the prematurely aged sleeve assembly.

The material of the high-temperature zone can be high-alloy transition metal. These materials are preferably iron and/or cobalt based sintered powder metal alloys. The amount of said alloy added to said iron and/or cobalt base is at least 10 wt.%, more preferably at least 25 wt.%, even more than 35 wt.%. The alloying elements may be incorporated in the master powder used in the compacted mixture in pre-alloyed form prior to sintering, or they may be mixed into the compacted mixture as separate elements or master alloys prior to sintering, or any combination of such techniques. During sintering, the alloying elements then become redistributed to give the desired sintered microstructure. In addition to iron and/or cobalt, the other alloying elements preferably include: 10-30 wt.% Cr, 0-25 wt.% Ni, 0-10 wt.% Mo, 0-8 wt.% W, 0-4 wt.% V, and 0.5-3.0 wt.% C. Other alloying elements may also be present depending on the particular operating environment.

The iron-based alloy or material includes a balance of iron. In other words, the remainder of the iron-based alloy or material is formed of iron such that the total content of alloy or material is equal to 100 wt.%. The cobalt-based alloy or material includes a balance of cobalt. In other words, the remainder of the cobalt-based alloy or material is formed of cobalt such that the total content of alloy or material is equal to 100 wt.%.

In one exemplary ferrous material, the primary alloying elements may be 15-25 wt.% Cr, 0-5 wt.% Ni, 1.5-6.5 wt.% Mo, 1-4 wt.% W, 1-3 wt.% V, and 0.5-2.5 wt.% C, with a more preferred composition being 18-24 wt.% Cr, 0-5 wt.% Ni, 1.5-6.5 wt.% Mo, 1-4 wt.% W, 1-3 wt.% V, and 0.8-2.4 wt.% C.

In one exemplary ferrous material, the primary alloying elements may be 10-25 wt.% Cr, 7-20 wt.% Ni, 1-7 wt.% Mo, 0-3 wt.% W, 0-3 wt.% V, and 0.5-3 wt.% C. In this material, a high Ni content is used to improve high temperature properties such as oxidation resistance and wear resistance. More preferred compositions are 13-25 wt.% Cr, 7-20 wt.% Ni, 1-7 wt.% Mo, 0-2 wt.% W, 0-2 wt.% V and 1-3 wt.% C.

In one exemplary ferrous material, the primary alloying elements may be 10-25 wt.% Cr, 10-21 wt.% Ni, 2-10 wt.% Mo, 0-3 wt.% W, 0-2 wt.% V, 4-20 wt.% Co, and 0.5-2 wt.% C. In this material, a combination of high Ni and high Co contents is used to further improve high temperature properties such as oxidation resistance and wear resistance. More preferred compositions are 13-25 wt.% Cr, 10-21 wt.% Ni, 2-10 wt.% Mo, 0-3 wt.% W, 0-2 wt.% V, 4-20 wt.% Co and 0.8-1.6 wt.% C.

In one exemplary cobalt-based material, the primary alloying elements may be 20-30 wt.% Cr, 5-15 wt.% Ni, 0-3 wt.% Mo, 5-10 wt.% W, 0-3 wt.% V, and 0.5-2 wt.% C. In this material, the use of the cobalt alloy matrix can still further improve high-temperature properties such as oxidation resistance and wear resistance. More preferred compositions are 20-30 wt.% Cr, 5-15 wt.% Ni, 0-2 wt.% Mo, 5-10 wt.% W, 0-2 wt.% V and 0.5-1.5 wt.% C.

Fig. 2, 5 and 8 show another embodiment of a multi-axial layer sleeve 110. Except beginning at 100, the reference numbers used here are the same as for the first embodiment. The sleeve includes three distinct axial regions, wherein the sintered powder metal alloy material of each region is best suited for the local environment associated with each region. Note that the three regions may all be different, where three unique sintered powder metal alloys will be used. Alternatively, as shown in fig. 8, the regions of the sleeve ends may have a common local environment that is different from the intermediate region separating the end regions. In the end use shown in fig. 8, the sleeve 110 is shown supporting the laterally loaded shaft 28, thereby imparting an uneven load to the sleeve 110, such that the axial end portions 120 are subjected to greater mechanical loads and therefore undergo greater wear than the intermediate portions. Knowing that the sleeve 110 for this particular application will be subjected to such variable load/wear environments, the sleeve 110 may be designed such that the axial end portions 120 are made from a sintered powder metal alloy that is different from the material used for the intermediate portion 122. As described above for the embodiments of fig. 1 and 4, the different parts will have different alloy compositions and/or microstructures, and may also be subjected to different processing (heat treatment, coating, surface finish, etc.) to produce different properties. In most cases, the differences will include variations in the alloy composition of the materials used for the various regions. For end load applications as shown in fig. 8, the material a of the high load/high end region 120 will comprise a material that exhibits high wear resistance at high mechanical loads, such as an iron-based alloy with 15-25 wt% Cr, 2-5 wt% Mo, 2-5 wt% W, 1-3 wt% V and 1.5-2.5 wt% C as the major alloying elements, while the material B selected for the low load/low wear intermediate region may be a low alloy material that does not require such high load/wear properties, such as an iron-based alloy with 10-15 wt% Cr and 0.5-1.5 wt% C as the major alloying elements.

Other applications may exist where the sleeve encounters a local environment, rather than an environment such as where a turbocharger is axially disposed or a side load environment. The different environments are arranged in the radial direction of the casing. In this case, the sleeve may be manufactured in a similar manner to that described above, but with the different parts arranged radially instead of axially. Such a sleeve 210 is schematically shown in fig. 3 and 6. In this example, the inner surface region 220 may experience a higher load or higher temperature or a combination thereof, which requires a high alloy powder metal sintering material, while the radially outer layer region 222 may experience a lower load or lower temperature or a combination thereof, which requires a different sintering powder metal alloy than the sintering powder metal alloy used for the inner surface radial region 220. In other applications, a key feature of the inner radial region 220 may be its tribological compatibility with the shaft material or surface finish, rather than simply its ability to withstand high temperatures and/or high mechanical loads. In this case, the outer radial region 222 may then be selected based on its excellent mechanical properties that are needed to provide mechanical support to the inner radial region. The same materials identified above in connection with the embodiments of fig. 1-2 may be suitable for use in the layers of the radial multi-layer sleeve 210 of fig. 3 and 6.

Different processes may be used to manufacture the sleeves of fig. 1-3.

Fig. 10 illustrates a method in which different alloy powders of selected materials a and B are simultaneously compacted in a first operation and then sintered as a single compact. This may be two, three or more layers and may be best suited for the axially layered sleeve 10, 110, although use in manufacturing the radially layered sleeve 210 is not excluded.

Fig. 11a-c show an alternative process in which the parts 20, 22, 120, 122 are individually pressed and then partially sintered at a temperature below the limit sintering temperature, and then joined by a process known as sinter brazing. The ends to be joined may be flat as shown in fig. 1g-h, or they may be shaped so that they nest to help pre-align the parts prior to sinter brazing. The radially layered sleeve 210 may similarly be manufactured using sinter brazing, and profile features may similarly be added to facilitate alignment prior to sinter brazing.

Still referring to fig. 1a-f, an alternative process may be envisioned in which the portions 20, 22120, 122 are individually pressed, then partially sintered at a temperature below the limit sintering temperature, and then joined by a process known as sinter bonding, in which there is no brazing addition. The ends to be joined may be flat or may be shaped so that they nest to help pre-align the parts prior to sinter bonding, as shown in fig. 1 lg-h. The radially-layered sleeve 210 may similarly be manufactured using sinter bonding, and profile features may similarly be added to facilitate alignment prior to sinter bonding.

12a-b illustrate yet another process in which portions 20, 22; 120 of a solvent; 122 are separately pressed and sintered and then joined by friction welding. Here, adjacent end faces of the portions may move relative to each other with sufficient force and motion to generate sufficient frictional heat to join the portions at the interface. This process would be well suited for axially layered casings 10, 110, although use in joining radially layered casings 210 is not excluded.

Fig. 9a and 9b show bearings 310, 410 that can be manufactured in a similar manner. The embodiment of fig. 9a shows a sintered powder metal material half shell bearing 310 in which axially spaced end portions 320 are made of material a and intermediate portions 322 are made of material B and bridge the end portions 320. Materials a and B may be the same sintered powder metal materials as those described above in connection with the manufacture of the sleeve, or may differ depending on the particular application. The axial region represents a localized environment of the bearing, which requires a different material, for reasons that have been explained in connection with the above-mentioned sleeve. The embodiment of fig. 9b is similar to fig. 9a, except that the layers 420, 422 are radially arranged (in a manner similar to the sleeve 210 of fig. 3).

The foregoing description is illustrative of the present invention and it will be understood and appreciated by those of ordinary skill in the art that other variations and embodiments are possible in light of the above teachings and are contemplated and incorporated herein.

It is contemplated that all of the features of the claims and all of the embodiments may be combined with each other, as long as such combinations are not mutually inconsistent.