Patent Application
20190293114
This invention relates generally to sliding-type bearings, and more particularly to those having a sintered powder metal bronze bearing material applied to a steel backing, such as used in engine bearings.
Internal combustion engines oftentimes include bearings comprising a lining formed of aluminum bonded to a backing formed of steel. After bonding the aluminum lining to the steel backing, the bearing is heat treated. However, the temperature of the heat treatment process is limited in attempt to prevent brittle intermetallic iron-aluminum phases from forming at the bond line. Certain higher temperature heat treatments are avoided in attempt to prevent formation of the intermetallic iron-aluminum phases.
One aspect of the invention provides a bearing comprising a backing formed of a steel material, a lining disposed along the backing, and a diffusion barrier layer disposed between the backing and the lining. The lining is formed of aluminum or an aluminum alloy, the diffusion barrier layer is formed of nickel or a nickel alloy, and the diffusion barrier layer has a thickness ranging from 1 micron to 100 microns.
Another aspect of the invention provides a method of manufacturing a bearing. The method comprises the steps of obtaining a bearing including a backing formed of a steel material, a lining formed of aluminum or an aluminum alloy disposed along the backing, and a diffusion barrier layer being formed of nickel or a nickel alloy disposed between the backing and the lining. The method further includes heating the bearing.
Yet another aspect of the invention provides a method of manufacturing a bearing. The method comprises disposing a lining formed of aluminum or an aluminum alloy along a diffusion barrier layer, the diffusion barrier layer being formed of nickel or a nickel alloy and having a thickness ranging from 1 micron to 100 microns; and disposing the diffusion barrier layer along a backing formed of a steel material.
These and other features and advantages of the present invention will become more readily appreciated when considered in connection with the following detailed description and appended drawing:
One aspect of the invention provides a bearing 10, washer, or bushing for an internal combustion engine. An example of the bearing is shown in
The bearing can have various different designs and/or dimensions depending on the particular application for which it is designed. In the example embodiment of
The diffusion barrier layer formed of the nickel or nickel alloy is typically disposed directly on the backing formed of the steel material, and the lining is typically disposed directly on the diffusion barrier layer. The diffusion barrier layer has a thickness t ranging from 1 micron to 100 microns.
The thickness of the diffusion barrier layer is significant. A thickness of less than 1 micron will be insufficiently effective in reducing the formation of iron-aluminum intermetallic during a heating step, while more than 100 microns may have adverse effects on the mechanical properties of the overall bearing product. In addition, alloying and similar modifications to the diffusion barrier layer may be done to enhance these properties, especially with thicker overall diffusion barrier layers.
In the finished bearing product, after a heat treatment of the bearing, the silicon particles are preferably present in the lining. Due to the diffusion barrier layer, the iron-aluminum intermetallic phases are typically not present in the backing layer, the lining, or the diffusion barrier layer. If the aluminum intermetallic phases are present, they are present in an amount which is insufficient to cause brittleness of the diffusion barrier layer, the backing layer, or the lining. Also, if present, the aluminum intermetallic phases are in an amount insufficient to cause failure of the bonds between the backing layer, diffusion barrier layer, and lining. Also, if present, the aluminum intermetallic phases would be in an amount too small to be observed in cross sectional examination at up to 500× magnification.
Another aspect of the invention provides a method of manufacturing the bearing. This method includes obtaining the bearing including the backing formed of the steel material, the lining formed of the aluminum or aluminum alloy disposed along the backing, and the diffusion barrier layer formed of the nickel or a nickel alloy disposed between the backing and the lining. The diffusion barrier layer preferably has a thickness ranging from 1 to 100 microns. These steps can include producing the backing, the lining, and/or the diffusion barrier layer in the form of a strip by various different methods.
The method further includes heating the lining of the bearing, for example heating the bearing to a temperature of at least 400° C. Typically, the heating step is conducted during a heat treatment process after the backing and the lining are bonded to one another with the diffusion barrier layer therebetween. The heating step can include forming the particles including silicon in the lining if silicon is in present as an alloying element in the lining. The diffusion barrier layer prevents or reduces the formation of the iron-aluminum intermetallic phases in the backing, the lining, and the diffusion barrier layer. Due to the diffusion barrier layer, the iron-aluminum intermetallic phases are typically not formed during the heating step. If the aluminum intermetallic phases are formed, they are present in an amount which is insufficient to cause brittleness of the diffusion barrier layer, the backing layer, or the lining. Also, if present, the aluminum intermetallic phases are in an amount insufficient to cause failure of the bonds between the backing layer, diffusion barrier layer, and lining. Also, if present, the aluminum intermetallic phases would be in an amount too small to be observed in cross sectional examination at up to 500× magnification.
Yet another aspect of the invention provides a method of manufacturing the bearing comprising the steps of disposing the diffusion barrier layer along the backing formed of the steel material, the diffusion barrier layer being formed of the nickel or a nickel alloy and having the thickness ranging from 1 micron to 100 microns; and disposing the lining formed of the aluminum or an aluminum alloy along the diffusion barrier layer.
The diffusion barrier layer can be disposed along or applied to the lining and/or the backing using various different techniques. According to one example embodiment, the method includes rolling the diffusion barrier layer onto the lining so that the diffusion barrier layer is clad to the lining prior to disposing the diffusion barrier along the backing, for example roll bonding the lining and clad diffusion barrier layer to the backing. Alternatively, the method can include plating the diffusion barrier layer onto the backing, and then disposing the lining along the diffusion barrier layer, for example roll bonding the lining to the plated diffusion barrier layer and backing.
As indicated above, the method includes bonding the lining to the backing with the diffusion barrier layer therebetween. The diffusion barrier layer can be disposed on the backing or the lining before the bonding process. Alternatively, the step of disposing the diffusion barrier layer between the lining and the backing is during the bonding process. An example bonding process includes roll bonding or rolling either the lining or the backing onto the diffusion barrier layer. The bonding can be referred to as hot bonding, where the bearing is heated during the bonding step, or cold bonding, where the bearing is not heated.
The method further includes heating the bearing after the bonding step, for example at a temperature of at least 400° C. The heating step can include forming the particles including silicon in the lining.
The method also includes forming or shaping the lining, backing, and diffusion barrier layer of the bearing into a desired shape, for example the shape described above which extends circumferentially around the center axis. The forming or shaping step can occur before or after the heating or heat treating step.
According to one preferred embodiment, the method first includes producing or otherwise obtaining the backing in the form of a steel strip, producing or otherwise obtaining the lining in the form of an aluminum strip, and producing or otherwise obtaining the diffusion barrier layer in the form of a nickel strip. Next, the method includes cladding the lining with the diffusion barrier layer or plating the backing with the diffusion barrier layer. After the cladding or plating step, the method includes bonding the lining to the backing with the diffusion barrier layer between the backing and the lining. After the bonding step, the method includes heat treating the lining by heating the entire bearing to a temperature of at least 400° C. The method further includes forming the bearing into a shape, for example the shape described above wherein the bonded backing, the lining, and diffusion barrier layer extend extends circumferentially around the center axis. The forming step is typically conducted after the bonding step and after the heating or heat treating step. Alternatively, the forming step can be conducted before the heating or heat treating step.
Obviously, many modifications and variations of the present invention are possible in light of the above teachings and may be practiced otherwise than as specifically described while within the scope of the following claims. In particular, all features of all claims and of all embodiments can be combined with each other, as long as they do not contradict each other.
