Copper alloy for valve seat inserts and valve guides and method of manufacturing

Abstract

A copper alloy for enhancing thermal conductivity and strength in a valve seat insert or guide material is provided. The copper alloy includes 3.0 wt. % to 5.0 wt. % iron, 3.0 wt. % to 5.0 wt. % zinc, and optionally 0.0 wt. % to 2.0 wt. % tin, based on the total weight of the copper alloy. The copper alloy can be water atomized to form particles, and the copper alloy particles can be blended with other particles and then pressed to form a slug. The slug containing the copper alloy is typically disposed between two porous parts formed of steel or another iron-based material to form a stack. The stack is sintered or otherwise heat-treated such that the copper alloy melts and infiltrates the pores of the porous parts. The copper alloy infiltrant is distributed more equally between the porous materials in the stack compared to prior art.

Description

710240-09942COPPER ALLOY FOR VALVE SEAT INSERTS AND VALVE GUIDES AND METHOD OF MANUFACTURING

[0001] The subject international (PCT) patent application claims priority7to U.S. provisional application no. 63 / 760,913, filed February 20, 2025, the entire contents of which is incorporated herein by reference.BACKGROUND OF THE INVENTION1. Field of the Invention

[0002] This invention relates generally to materials used to form valve seat inserts and valve guides, such as copper alloys for infiltrating parts made of various compacted powder metal alloys. The invention also relates to valve seat inserts and valve guide materials including the copper alloys, and methods of manufacturing the same.2. Related Art

[0003] Valve seat inserts are critical components in internal combustion engines, primarily utilized in vehicles to facilitate efficient heat transfer from the valve to the cylinder head. These inserts are designed to provide a tight seal against combustion pressure and essential wear protection to both the valve and the cylinder head. The valve seat insert is ty pically made from durable materials that can withstand high temperatures and pressures, thereby enhancing the longevity and performance of the engine. Additionally, valve guides, which are cylindrical bushings affixed to the cylinder head, play a vital role in supporting the valve's movement, ensuring proper alignment, and reducing friction during operation.

[0004] Materials used to form the valve seat inserts and valve guides are ty pically primarily tool steel, stainless steel, or another type of steel or iron-based material in powder form. Other materials, typically in powder form, can also be used, such as cobalt, nickel, chromium, or molybdenum alloys, referred to as a base powder. The base pow der is blended with other base powders, additives, and / or hard particles, to form a blended powder. The blended powder is ty pically pressed to form a porous green compact / part. The porous green compact, or a plurality of the porous green compacts, are then sintered or heat-treated to form the valve seat insert or valve guide material. The particles in the green porous compacts bond together during the sintering or heat treatment.

[0005] In some cases, copper or a copper alloy is infdtrated into the pores of the green porous powder compact or the porous powder metal part during the sintering or other heat treatment process to increase thermal conductivity and / or provide another desirable710240-09942characteristic in the finished material. For example, a slug formed of a copper alloy powder compact can be located between two of the porous compacts / parts at a temperature above the melting temperature of the copper alloy so that the copper alloy infiltrates the pores of both compacts / parts by capillary action.

[0006] However, it has been found that in some cases, a greater amount of the copper alloy infiltrates the compact above or below the copper slug. In this case, undesirable effects may result. For example, the finished sintered material may not achieve the desired density or copper content. More copper and higher density could be present in one compact compared to the other compact after the sintering step. Accordingly, improvements in the infiltration of the copper alloy in the compacts / parts are desired.SUMMARY

[0007] One aspect of the disclosure provides an atomized copper alloy which can be used in a valve seat insert or valve guide. The atomized copper alloy includes 3.0 wt. % to 5.0 wt. % iron, 3.0 wt. % to 5.0 wt. % zinc, optionally up to 2.0 wt. % tin, other elements each in an amount of not greater than 0.5 wt. % and in a total amount of not greater than 2.0 wt. %. and a remainder of copper, based on the total weight of the copper alloy.

[0008] Another aspect of the disclosure provides a material for a valve seat insert or valve guide. The material comprises a first porous part and a second porous part. Each porous part comprises at least one type of powder which is often steel and / or an ironbased material in an amount of at least 50 wt. %, based on the total weight of the green compact. The material further includes a slug formed at least in part of an atomized copper alloy powder. The slug is located between the first porous part and the second porous part. The atomized copper alloy powder includes 3.0 wt. % to 5.0 wt. % iron, 3.0 wt. % to 5.0 wt. % zinc, optionally up to 2.0 wt. % tin, other elements each in an amount of not greater than 0.5 wt. % and in a total amount of not greater than 2.0 wt. %, and a remainder of copper, based on the total weight of the atomized copper alloy.

[0009] Another aspect of the disclosure provides a method of manufacturing a material for a valve seat insert or valve guide. The method includes atomizing a copper alloy. The atomized copper alloy includes 3.0 wt. % to 5.0 wt. % iron, 3.0 wt. % to 5.0 wt. % zinc, optionally up to 2.0 wt. % tin, other elements each in an amount of not greater than 0.5 wt. % and in a total amount of not greater than 2.0 wt. %, and a remainder of copper, based on the total weight of the atomized copper alloy.710240-09942

[0010] Another aspect of the disclosure provides a method of manufacturing an atomized copper alloy or a material for a valve seat insert or valve guide.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Other advantages of the present invention will be readily appreciated, as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawing wherein:

[0012] Figure 1 illustrates a stack formed of a slug including a copper alloy located between a first porous part and a second porous part before a sintering or melting step, according to an example embodiment.DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0013] One aspect of the disclosure provides a material including at least 50 wt. % of an atomized copper alloy. The copper alloy is optionally blended with other powders for use in valve seat inserts, valve guides, and other components. The copper alloy can be melted, sintered or otherwise heat-treated between porous parts, typically each formed of steel or another iron-based material, so that the copper alloy infiltrates the pores of the porous parts. The porous parts could alternatively be formed of another material such as, but not limited to, cobalt, molybdenum, and chromium. The copper alloy infiltrates the porous parts in an approximately equal amount, so that the density of the porous parts and the copper content in the porous parts are approximately equivalent to one another in the sintered material.

[0014] According to example embodiments, the atomized copper alloy includes 3.0 wt. % to 5.0 wt. % iron, 3.0 wt. % to 5.0 wt. % zinc, optionally 0.0 wt. % to 2.0 wt . % tin, other elements each in an amount of not greater than 0.5 wt. % and in a total amount of not greater than 2.0 wt. %, and a remainder of copper, based on the total w eight of the atomized copper alloy. Typically, the atomized copper alloy includes 3.5 wt. % to 3.9 wt. % iron, 3.4 wt. % to 3.8 wt. % zinc, 0.11 wt. % to 0.15 wt. % tin, other elements each in an amount of not greater than 0.2 wt. % and in a total amount of not greater than 1.0 wt. %, and a remainder of copper, based on the total weight of the copper alloy. According to a preferred embodiment, the atomized copper alloy includes 3.7 wt. % iron, 3.6 wt. % zinc, and 0.13 wt. % tin, based on the total weight of the copper alloy. Another preferred embodiment, the atomized copper alloy includes 3.7 wt. % iron and 3.6 wt. % zinc, based on the total weight of the copper alloy. The atomized copper alloy also preferably includes a remainder710240-09942or balance of copper. Typically, the copper alloy includes at least 50 wt. %, or at least 75 wt. %, or at least 90 wt. % of the copper, based on the total weight of the copper alloy.

[0015] The copper alloy may include other elements besides copper, iron, zinc, and tin, but the other elements are preferably limited. For example, the copper alloy may include one or more other elements in a total amount of not greater than 2 wt. %, or not greater than 0.5 wt. %, or not greater than 0.1 wt. %, based on the total weight of the copper alloy. For example, one or more other elements present in the copper alloy may include unavoidable impurities. If the other element or elements are present, each is preferably in an amount of not greater than 0.5 wt. %, or not greater than 0.2 wt. %, or not greater than 0.1 wt. %, based on the total weight of the copper alloy.

[0016] The copper alloy may be provided in the form of particles, such as water atomized particles or gas atomized particles. The copper alloy particles typically have a particle size ranging from 5 to 200 microns.

[0017] The atomized copper alloy particles may be pressed to form a slug 10 which is then used to infdtrate and form the material for use as the valve seat insert or valve guide. However, the copper alloy particles are typically blended with additional particles to form the material, such as particles of brass, silicon, manganese, tin and / or oxides. The blended particles can then be pressed together to form the slug 10, which is then used to form the valve seat insert or valve guide material.

[0018] According to example embodiments, the slug 10, which is formed at least in part of the copper alloy, is disposed between a first porous part 12, also referred to as a first green compact, and a second porous part 14, also referred to as a first green compact, which will together form two valve seat inserts or valve guide. The first porous part 12 and the second porous part 14 are formed primarily of steel and / or another iron-based material. For example, each porous part 12, 14 can be formed primarily of tool steel, such as M2, M3 / 2, or M35 tool steel. Alternatively, the porous parts 12, 14 could be formed of stainless steel or other metals such as but not limited to cobalt or molybdenum.

[0019] The porous parts 12, 14 can also include at least one of an additive, a hard particle, and / or an infiltrant blended with the steel or other iron-based material.Typically, each porous part 12, 14 includes a combination of the steel or other iron-based material, additives, hard particles and infiltrants. Example additives that can be present in the porous parts 12, 14 include at least one of graphite, a sulfide, and copper. The additives can serve as a lubricant or enhance machinability. The porous parts 12, 14 are typically710240-09942formed by blending particles of the steel, particles of the additives, hard particles, and particles of the infiltrant together, and then pressing the blend to form the porous part 12, 14.The porous parts 12, 14 preferably have a porosity above 5% after the pressing step.

[0020] Once the slug 10 including the copper alloy is placed between the first and second porous parts 12, 14 to form a stack, the stack is sintered or heat-treated in another manner such that the copper alloy from the slug 10 melts and infiltrates pores of the first porous part 12 and pores of the second porous part 14. The copper alloy infiltrates the first and second porous parts 12, 14 in approximately equal amounts. Thus, after the sintering or heat-treating, the density of the first porous part 12 and the density of the second porous part 14 differ by not greater than 10%, preferably not greater than 5%. The copper content is approximately equal in the first and second part 12, 14 after the infiltration of the copper alloy. These characteristics are typically ideal in order to meet specifications for valve seat insert and valve guide materials. In other words, the novel copper alloy helps to avoid the problem of more copper and higher density in one part compared to the other in the stack after the sintering step. The infiltration achieved by the copper alloy according to the present invention is much more equal than in the prior art.

[0021] Another aspect of the disclosure provides a method of manufacturing a material for a valve seat insert or valve guide which includes the copper alloy described above.

[0022] The method first includes atomizing a melt, wherein the melt is formed of the copper alloy. As stated above, the copper alloy includes 3.0 wt. % to 5.0 wt. % iron, 3.0 wt. % to 5.0 wt. % zinc, and optionally 0.0 wt. % to 2.0 wt. % tin, based on the total weight of the copper alloy. According to one preferred embodiment, the copper alloy includes 3.7 wt. % iron, 3.6 wt. % zinc, and 0.13 wt. % tin, based on the total w eight of the copper alloy. According to another preferred embodiment, the copper alloy includes 3.7 wt. % iron and 3.6 wt. % zinc, based on the total weight of the copper alloy. The copper alloy also preferably includes a remainder or balance of copper. Typically, the copper alloy includes at least 50 wt. %, or at least 75 wt. %, or at least 90 wt. % of the copper, based on the total weight of the copper alloy.

[0023] The atomization step forms particles of the copper alloy and preferably includes water-atomizing. The elements present in the copper alloy preferably experience a low' level of oxidation during the w ater-atomizing step. Preferably, the elements present in the copper alloy experience less oxidation than manganese. After the atomizing step, the710240-09942particles of the copper alloy can be blended with additional particles to form a blend. For example, the water-atomized particles of the copper alloy can be blended with particles including at least one of brass, silicon manganese, tin. and oxides to form a blend.

[0024] The method next includes pressing the copper alloy particles, either alone or in combination with the other particles, to form the slug 10. The method further includes locating the slug 10 between the first porous part 12 and the second porous part 12 to form the stack. Finally, the method includes sintering or heat treating the stack in another manner which melts the slug 10 to then infiltrate the first and second porous parts 12, 14. The temperature of the sintering or other heat treating should be greater than the melting temperature of the copper alloy so that the copper alloy infiltrates the pores of the porous parts 12, 14 by capillary action. Figure 1 is an example of the slug 10 located between the porous parts 12, 14 before the sintering step.

[0025] 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.

Claims

710240-09942CLAIMS1. A copper alloy, comprising:3.0 wt. % to 5.0 wt. % iron,3.0 wt. % to 5.0 wt. % zinc,optionally up to 2.0 wt. % tin,other elements each in an amount of not greater than 0.5 wt. % and in a total amount of not greater than 2.0 wt. %, anda remainder of copper, based on the total weight of the copper alloy.

2. The copper alloy of claim 1, wherein the copper alloy is in the form of particles.

3. The copper alloy of claim 2, wherein the particles have a particle size ranging from 5 to 200 microns.

4. The copper alloy of claim 1, wherein the copper alloy is in the form of pressed particles.

5. The copper alloy of claim 1 including 3.5 wt. % to 3.9 wt. % iron, 3.4 wt. % to 3.8 wt. % zinc. 0.11 wt. % to 0.15 wt. % tin, other elements each in an amount of not greater than 0.2 wt. % and in a total amount of not greater than 1.0 wt. %, and a remainder of copper, based on the total weight of the copper alloy.

6. The copper alloy of claim 1, wherein the copper alloy consists of 3.7 wt. % iron, 3.6 wt. % zinc. 0.13 wt. % tin. other elements besides copper, iron, zinc, and tin in a total amount of not greater than 0.5 wt. %, and a remainder of copper, based on the total w eight of the copper alloy.

7. The copper alloy of claim 1, wherein the copper alloy consists of 3.7 wt. % iron, 3.6 wt. % zinc, other elements besides copper, iron, zinc, and tin in a total amount of not greater than 0.5 wt. %, and a remainder of copper, based on the total weight of the copper alloy.

8. A material for a valve seat insert or valve guide, comprising:710240-09942a first porous part and a second porous part, each porous part comprising:at least one of steel and / or an iron-based material in an amount of at least 50 wt. %, based on the total weight of the porous part;a slug formed at least in part of an atomized copper alloy located between the first porous part and the second porous part, the copper alloy comprising:3.0 wt. % to 5.0 wt. % iron,3.0 wt. % to 5.0 wt. % zinc,optionally up to 2.0 wt. % tin,other elements each in an amount of not greater than 0.5 wt. % and in a total amount of not greater than 2 wt. %, anda remainder of copper, based on the total weight of the copper alloy.

9. The material of claim 8, wherein the copper alloy from the slug is infiltrated in pores of the first porous part and in pores of the second porous part.

10. The material of claim 8, wherein the density of the first porous part and the density of the second porous part differ by not greater than 10%.

11. The material of claim 8, wherein the first porous part and the second porous part have a porosity’ of above 5%.

12. The material of claim 8, wherein the first porous part, the second porous part, and the slug are sintered together.

13. The material of claim 8, wherein the slug further includes at least one of brass, silicon, manganese, tin, and an oxide blended with the copper alloy.

14. A method of manufacturing a material for a valve seat insert or valve guide, comprising the steps of:atomizing a copper alloy, the copper alloy comprising3.5 wt. % to 3.9 wt. % iron,3.4 wt. % to 3.8 wt. % zinc,optionally up to 0.5 wt. % tin,710240-09942other elements each in an amount of not greater than 0.5 wt. % and in a total amount of not greater than 2 wt. %, anda remainder of copper, based on the total weight of the copper alloy.

15. The method of claim 14, wherein the atomizing includes water atomizing.

16. The method of claim 15, wherein the copper alloy is in the form of particles after the atomization step; and including the step of blending the atomized copper alloy particles with additional particles, the additional particles including at least one of brass, silicon manganese, tin, and an oxide to form a blend.

17. The method of claim 16 wherein the blend is pressed to form a slug.

18. The method of claim 15, wherein the copper alloy is in the form of particles after the atomization step; further including the step of pressing the atomized particles to form a slug; and locating the slug between a first porous part and a second porous part to form a stack.

19. The method of claim 18 including sintering or heat-treating the stack in a matter which causes the copper alloy from the slug to infiltrate pores of the first porous part and pores of the second porous part.

20. The method of claim 19, wherein the density of the first porous part and the density of the second porous part differ by not greater than 10% after the sintering or heat-treating step.

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