Patent Application
20130337215
The present disclosure relates generally to remanufactured components, and more particularly to a FeAlSiC thermal spray coating that is millable and oxidation resistant at about 700° C.
Because manufacturing new components can be extremely expensive, engineers are constantly seeking ways to refurbish or remanufacture used components to match technical and dimensional specifications for the component as new. For instance, in the engine industry there is a continuous effort to find new and more economical ways to remanufacture components, such as engine blocks and engine heads. Remanufacturing metallic components often requires adding material to the used body to build up a surface that no longer satisfies a dimensional specification for the component. For instance, in the case of an engine block, the distance between the head face and a centerline of a crank shaft support bore may have slightly decreased over the life of the used block. Therefore, in order to remanufacture the engine block, the head face needs to have material added, and then the treated component often needs to be reshaped by removing some of the added material to return all dimensions to specification. While there exists many different techniques for remanufacturing a component, the newly added material often also must exhibit characteristics that match or exceed the metallic material of the original component. For instance, in the case of an engine head or engine block, the added material must successfully undergo many cycles of being heated from ambient temperature to combustion temperatures on the order of about 700° C., be exposed to corrosive gases, and do so without degradation on par with the base metallic material, which may be steel or cast iron. Apart from these considerations, cost of the added material can be a constraint as well as the ability of the added material to be shaped economically back into specification. Thus, finding a technique to add the material, and finding an appropriate metallic material for addition in a remanufacturing procedure while satisfying many different and often conflicting constraints, including cost, can be extremely elusive.
The present disclosure is directed toward one or more of the problems set forth above.
In one aspect, a remanufactured component includes a body having a first shape resulting from use of the component. The first shape is defined by a first metallic material and has at least one dimension that does not match a dimensional specification for the component. A coating of a second metallic material is adhered to and covers at least a portion of the first metallic material on the body and has a milled external surface. The second metallic material comprises FeAlSiC and has a millable, predominantly ordered DO3 crystal structure with a substantially stable aluminum oxide scale that produces oxidation resistance at about 700° C. The body and the coating have a second shape that substantially matches the dimensional specification for the component.
In another aspect, a thermal spray wire includes a coil of FeAlSiC wire shaped and sized to be compatible with a wire arc thermal spray machine. The wire has 6-8% aluminum, 2.2-4.2% silicon, 1.6-2.4% carbon, and a remaining balance of iron.
In still another aspect, a method of remanufacturing a component includes identifying a dimension of a body that does not match a dimensional specification for the component. The body has a first shape resulting from use of the component, and is defined by a first metallic material. A second metallic material is thermal spray coated onto the body to build up the dimension beyond the dimensional specification for the component. The second metallic material is comprised of FeAlSiC. A portion of the second metallic material is milled away until the coating and the body have a second shape that substantially matches the dimensional specification of the component. The coating has a predominantly ordered DO3 crystal structure with a substantially stable aluminum oxide scale that produces oxidation resistance at about 700° C.
There are many different components, particularly engine components, that can be remanufactured and returned to service for a second useful life that may even exceed the useful life of a newly manufacture component. A used component will typically have a uniform body with a first shape resulting from use of the component. Those skilled in the art will appreciate that the dimensional specification for a component is often identified in an engineering drawing that typically specifies materials, surface finishes, a plurality of dimensions, and often tolerances about those dimensions and other specifications known in the art. Depending upon the component, the first shape of the body of the component resulting from use may be attributed to at least one of wear and/or degradation, and removal of additional material from the body in order to properly prepare a surface for remanufacturing. For instance, it might be desirable to remove some of the original first metallic material so that the resulting coating, after being milled, has some minimum thickness. In any event, the shape of the body will include at least one dimension that does not match the dimensional specification for the component. Parts that may be subject to remanufacture include, but are not limited to, engine heads, engine blocks, shafts, oil coolers, pump/turbo/engine housings, covers, intake/exhaust fittings and many others.
In one specific example, current remanufacturing strategies for a cylinder head or block may utilize 420 stainless steel to build up the body that is worn or machined out of dimensional specifications. While such a strategy has worked well, environmental and other concerns have motivated the industry to adopt remanufacturing materials that avoid, limit or reduce the use of chromium or nickel. Although not necessarily true for all components subject to remanufacture, engine heads and blocks, for instance, should be able to exhibit good oxidation resistance at about 700° C. The term “about” means a number rounded to the nearest significant digit. Thus, 749° C. is about 700° C., but 760° C. is not about 700° C.
Referring to
Referring to
The present disclosure teaches applying the second metallic material in a thermal spray coating strategy, such as utilizing a twin wire arc thermal spray technique of a type well known in the art. For example,
Rather than stainless steel as a remanufacture second metallic material, the present disclosure teaches the use of FeAlSiC wire in the dual wire arc thermal spray machine of
One specific recipe for a FeAlSiC wire suitable for use in remanufacturing engine heads 20 and engine blocks 30 that has worked well includes 6-8% aluminum, 2.2-4.2% silicon, 1.6-2.4% carbon and a remaining balance of iron. Nevertheless, there are other combinations of these elements that will exhibit the ordered DO3 crystal structure that yields a millable metallic material with a stable aluminum oxide scale.
The diagram of
Referring again to
The present disclosure finds potential applicability in any remanufacture strategy where there is a desire to at least one of reduce cost of the coating material, reduce cost or improve efficiency with regard to the application and machining of the coating, and finally maybe an environmental desire to avoid or reduce usage of chromium. The present disclosure finds specific application in substituting the FeAlSiC coating of the present disclosure in place of maybe the stainless steel used in the past to remanufacture engine components, such as engine heads and engine blocks.
As part of the remanufacture process, one might identify a dimension 12 or 112 (
It should be understood that the above description is intended for illustrative purposes only, and is not intended to limit the scope of the present disclosure in any way. Thus, those skilled in the art will appreciate that other aspects of the disclosure can be obtained from a study of the drawings, the disclosure and the appended claims.
