KR101332617B1 - Harmless self-lubricating alloy having excellent wear resistance and corrosion resistance, and sliding member producted by that - Google Patents

Abstract

The present invention relates to a self-lubricating alloy used for a sliding member in which a metal and a metal are in contact with and friction with each other, and a sliding member for a mechanical device manufactured therefrom, wherein the weight is C: 0.03 to 0.1%, Si: 0.1-5.0%, Mn: 0.5-1.5%, Ni: 55-70%, Cr: 3-10%, Mo: 3-8%, Bi: 1-6%, Sn: 1-5%, Se : Provides eco-friendly self-lubricating alloy excellent in corrosion resistance and abrasion resistance, characterized in that consisting of 0.5 ~ 3.0%, the balance Fe and other unavoidable impurities and a sliding member for a mechanical device manufactured therefrom.
According to the present invention, by increasing the alloy content of Mo in the existing Ni, Cr to improve the corrosion resistance and low thermal expansion properties, to form Co, W carbonitride to improve the high temperature strength and wear resistance, and the resinous phase of the matrix structure by the addition of Se By densifying and miniaturizing the tissue to increase self-lubricating and finely dispersing finely dispersed Ni-Bi-based intermetallic compounds in the dendritic tissue, there is no galling and seizing phenomenon and friction coefficient Also, since the service life is extended and self-lubricating alloys having various properties can be obtained.

Description

Eco-friendly self-lubricating alloy with excellent corrosion resistance and abrasion resistance and sliding member for mechanical devices {HARMLESS SELF-LUBRICATING ALLOY HAVING EXCELLENT WEAR RESISTANCE AND CORROSION RESISTANCE, AND SLIDING MEMBER PRODUCTED BY THAT}

The present invention relates to a nickel-based lubrication alloy, and more particularly, a metal in which a metal, such as a bearing, a valve seat, a landing gear, a wear ring, a rotor of a pump, and the like are in contact with and rubbed against each other. The present invention relates to a self-lubricating alloy used in the eastern part.

Generally, sliding members such as bearings, valve seats, landing gears, wear rings, and pump rotors are subjected to large thermal and mechanical loads due to repeated contact and friction caused by acceleration, opening and closing movements under severe conditions of high temperature. In addition, the degree of wear is severe, the damage caused by fatigue, corrosion, etc. due to wear is large, and the life of the product is greatly shortened due to galling and seizing.

In order to solve such a phenomenon, a method of improving the lubrication property by coating a solid lubrication layer on the surface of the Fe-based alloy has been proposed in the past, but the coated solid lubrication layer is weakly damaged due to its weak bonding strength with the alloy, and the solid lubrication layer Since the service life of the sliding member is determined according to the service life of, there is a problem that it is difficult to expect long life.

In addition, Japanese Laid-Open Patent Publication No. 1992-099834 (published on March 31, 1992) discloses a technique in which graphite and molybdenum disulfide are added to a Cu-Sn alloy to improve resistance and abrasion resistance to aging and to increase lubricity by adding Pb. Although this has been proposed, it is difficult to apply in the condition that lubrication is not possible, the upper limit temperature for use is only 300 ℃, the strength and abrasion resistance at high temperatures are deteriorated, there is a problem that is harmful to the human body when the heavy metal Pb is added.

In addition, U.S. Pat.Nos. 31,45099,4702887,5242657,6059901 and the like have been proposed to improve the lubrication properties by adding Bi to Pb instead of Pb. Due to the rough peeling of the surface, due to the low precision of the machine there is a limit to apply to the field of various machinery, there is a problem that the life of the member is also shortened.

The present invention has been made to solve the above problems, the corrosion resistance and low thermal expansion is improved by increasing the alloy content of Mo in Ni, Cr, the high temperature characteristics and wear resistance is improved by the formation of Co, W carbide, the effect of Se addition Densify and refine the matrix structure to increase self-lubricating and finely disperse and precipitate Ni-Bi-based intermetallic compounds, eliminating galling and seizing and reducing friction coefficient The purpose of the present invention is to provide an eco-friendly self-lubricating alloy and a sliding member for a mechanical device with excellent corrosion resistance and abrasion resistance with extended service life.

The present invention is Si: 0.1 to 5.0% by weight, Mn: 0.5 to 1.5%, Ni: 55 to 70%, Cr: 3 to 10%, Mo: 3 to 8%, Bi: 1 to 6%, Sn: It provides an environmentally friendly self-lubricating alloy having excellent corrosion resistance and abrasion resistance, comprising 1 to 5%, Se: 0.5 to 3.0%, balance Fe and other unavoidable impurities.

At this time, it also has the characteristic in containing C: 0.03-0.1% further by weight.

In addition, there is a feature in that it further contains at least one selected from Co: 0.5 to 3.0% and W: 0.5 to 2.0% by weight.

In addition, the alloy has a dense and fine dendritic structure and austenite structure, the dendritic structure is characterized in that the average spacing of the branches is 10㎛ or less (excluding 0).

In this case, the Ni-Bi-based intermetallic compound is finely dispersed and formed in the interval between the branches of the dendritic structure.

In addition, the present invention provides a sliding member for a mechanical device made of an environmentally friendly self-lubricating alloy excellent in corrosion resistance and wear resistance.

According to the present invention, the corrosion resistance and low thermal expansion properties are improved by increasing the content of Mo alloy in Ni and Cr, and the high temperature strength and wear resistance are improved by the formation of Co and W carbides, and the dendritic structure as a base structure is densified and refined under the influence of Se addition. Increase self-lubricating, finely disperse and deposit Ni-Bi-based intermetallic compounds in dendritic tissue, avoid galling and seizing and reduce friction coefficient. It is possible to obtain a self-lubricating alloy having an extended life and having various properties.

Hereinafter, the configuration of the present invention will be described in detail with reference to examples.

The present inventors have completed the present invention by repeating the research and experiment to ensure the excellent properties of the self-lubricating alloy, while being environmentally friendly, improved corrosion resistance and wear resistance at the same time.

As a result, the present invention includes low carbon, and increasing the alloy content of Mo in Ni and Cr makes it possible to sufficiently dissolve Mo in the matrix while preventing overproduction of carbides, and to evenly disperse Cr in the tissue to By promoting uniform formation, the hardness, abrasion resistance and corrosion resistance of the tissue can be improved at the same time, and there is little deformation even at a high temperature, so it is excellent in low thermal expansion.

Here, when Co and W alloys are additionally added alone or in combination, precipitation of Co and W carbides improves the high temperature strength and wear resistance of the alloy surface.

In addition, dendrite structure, which is a known structure, is compacted and refined through optimization of process conditions such as addition of Se and cooling rate, which are harmless to the human body, and fine and uniform dispersion and precipitation of Ni-Bi-based intermetallic compounds in such dendrite structures By this, the self-lubrication characteristics of the alloy is increased to reduce the friction coefficient, to prevent galling and seizing, thereby improving wear resistance, thereby maintaining mechanical precision and airtightness, and extending the service life of the present invention. Self-lubricating alloys can be obtained.

In addition, lubrication precipitates are produced to reduce the kinetic resistance to friction, to offset the total energy loss, and the wedge shape is formed on the frictional movement surface through the precipitate to form a space for storing lubricating oil on the movement surface. By reducing friction, it has excellent self-lubricating performance.

First, the reason for component limitation of this invention is demonstrated (Hereinafter, weight% is simply described as%).

Silicon (Si) is an element that improves castability by improving the fluidity of molten metal and deoxidizes during dissolution, and is partially dissolved in steel to improve hardness. When Si content is less than 0.1%, deoxidation effect and hardness may be reduced. In addition, when the content of Si exceeds 5.0%, segregation may occur or the fluidity of the alloy may not be high to obtain a uniform structure, and there is a problem in that the toughness is lowered, and the content of Si is limited to 0.1 to 5.0%.

Manganese (Mn) is an element that improves the fluidity of the alloy, nickel alloy has a problem of poor fluidity due to the high content of Ni, in the present invention, by increasing the flowability by including Mn in the optimum range, the castability, austenite It acts as a stabilizing element, some as a deoxidizer.

The Mn should be added at least 0.5% in order to ensure the fluidity and castability as the target in the present invention, but when the content of Mn exceeds 1.5%, the workability is reduced, the content of Mn is limited to 0.5 ~ 1.5%.

Nickel (Ni) is an element that is useful for improving wear resistance and anti-galling including hardness and toughness, and is a major element that disperses and precipitates Ni-Bi-based intermetallic compounds (NiBi _3, etc.) in dendritic tissues known upon cooling. It is preferable to add more than 55%. However, when the Ni content exceeds 70%, the toughness is lowered, and wear resistance and mechanical strength are lowered due to low strength precipitates, so the Ni content is limited to 55 to 70%.

In addition, since Ni has various oxidation numbers as transition metals, it is advantageous to form various oxides, and it is easy to manufacture alloys with other metals, and in particular, a base metal matrix phase for forming precipitates of post-transition metals. In addition, since the corrosion resistance and heat resistance are excellent, the application range of the alloy can be expanded.

Chromium (Cr) is an element that generates Cr carbide and improves high temperature strength, abrasion resistance, corrosion resistance, and low thermal expansion. As chromium (Cr) helps form austenite structure, it is preferably added at least 3%. However, when the content of Cr exceeds 10%, coarse chromium carbides are precipitated and cause a decrease in the known toughness, so the content of Cr is limited to 3 to 10%.

Molybdenum (Mo) is an element that is excessively added to improve the hardness and corrosion resistance of the tissue by matrix solid solution and even dispersion of Cr in the structure, and promotes the formation of chromium carbide by promoting such solid solution strengthening and even dispersion of Cr. In order to improve hardness and corrosion resistance, it is preferable to add 3% or more. However, when the Mo content exceeds 8%, the manufacturing cost increases, toughness decreases due to excessive solid solution strengthening, and moldability decreases. It is limited to 3-8%.

Bismuth (Bi) is an element that disperses Ni-Bi-based intermetallic compounds deposited in dendritic structure to have lubricating properties, and is particularly useful for replacing Pb with a sliding material in a condition in which lubricating oil cannot be used. Since it is a post-transition metal, it has a low melting point and a very low coefficient of friction, thereby softening the surface of the alloy and improving the self-lubrication property by lowering the coefficient of friction by transferring Bi to the counterpart metal surface when worn by friction.

In order to effectively exhibit such lubricating properties, it is preferable to add Bi content of 1% or more. However, when the Bi content exceeds 6%, the effect is saturated, the cost increases, and the castability is poor. It is limited to -6%.

Starium (Sn) exists in solid solution inside the alloy to induce precipitation of Ni-Bi-based intermetallic compounds in matrix, and contributes to the improvement of fluidity and solidification shrinkage during casting. Since the precipitate contained in the form of a needle-like resin is lubricated solid, the precipitate breaks when friction with the counterpart metal surface, the powder is sprinkled to modify the adhesion.

In order to improve the lubricity, the Sn content is preferably added by 1% or more. However, when the Sn content exceeds 5%, the addition effect is saturated and the castability and retardability are low. Therefore, the Sn content is 1-5. It is limited to%.

Selenium (Se) is an element that turns the matrix into dendritic tissue, promotes the formation of nuclei, and finely and uniformly disperses the dendritic tissue to further improve self-lubrication function and increases the machinability of the alloy. The content of Se is preferably 0.5% or more. However, if the content of Se is more than 3.0%, it is a rare metal series, which greatly affects the manufacturing cost, so the content of Se is 0.5 to 3.0. It is limited to%.

In particular, Se is a semi-metal component, which improves the non-hardness of non-hardness, further improves corrosion resistance, and increases the size of precipitates distributed in tissues. Maximizing the number has a decisive influence on ultra miniaturization.

In addition, by containing at least one selected from Co: 0.5 to 3.0% by weight and W: 0.5 to 2.0% by weight, the effect of improved wear resistance and high strength can be obtained, and cobalt (Co) improves corrosion resistance and In addition, Co is preferably added in an amount of 0.5% or more because it combines with carbon to form carbides to improve surface strength and wear resistance, as well as to refine the dendritic structure by dispersing Co carbide. However, if the Co content is more than 3.0%, the workability is lowered, so the processing cost is increased, and because it becomes a factor to inhibit the self-lubrication function due to segregation during casting, Co content is limited to 0.5 ~ 3.0%.

Tungsten (W) is effective in promoting precipitation in alloys and improving high temperature strength, and is an element that forms carbides by combining with carbon, and contributes to stabilization of austenite structure while becoming such Ni-Co-W carbides.

In order to distribute | distribute to the interface of matrix structure by dispersion | distribution, it is preferable to contain W 0.5% or more. However, if W is contained in excess of 2.0%, the workability is lowered, the content of W is limited to 0.5 ~ 2.0%.

Carbon (C) is an element which raises the strength and hardness of the matrix and precipitates carbides to contribute to the improvement of the wear resistance of the matrix. In the present invention, carbon (C) is dissolved in the matrix or reacted to the formation of carbide with Cr, Co, and W. Mainly consumed.

At this time, it is also important to manage each of the above-described component elements alone, but in order to secure the mechanical properties of the high temperature and room temperature aimed at by the present invention, the relationship between each component element and the effect of the formation of solid solution elements, precipitates and carbides in the alloy It is necessary to consider.

The alloy of the present invention comprises the above components and consists of the remainder Fe and other unavoidable impurities. And alloy elements may be further added as needed to improve the properties of the present alloy, alloy elements that are not identified in the embodiment of the present invention is not interpreted to be excluded from the scope of the present invention.

Meanwhile, the alloy according to the present invention has a dendrite structure and an austenite structure, but the dendritic structure becomes coarse when the cooling rate is slowed down, and turbulence phenomenon occurs during solidification under the influence of different specific gravity and temperature between the elements. As it is generated and has a different cooling rate, it is a major cause of defects such as cracks and pinholes due to continuous gas generation, thereby minimizing gas generation by increasing the cooling rate.

If the cooling rate is increased in this way, the gap between the primary and secondary branches of the dendritic branch becomes narrower. For example, if the cooling rate increases even in the liquid phase around the branch, the branch becomes unstable to form a new branch. The spacing between branches becomes narrower because they try to reduce sexual overcooling.

The mechanical strength of dendritic tissue is related to the amount, distribution, and homogeneity of precipitates distributed in the tissue, but more closely related to the spacing of branches. That is, the narrower the gap between the branches, the more finely dispersed the precipitate is made more homogenous, which has a great effect on the mechanical strength and lubrication performance of the alloy.

Therefore, the present invention dissolves the alloy components to form an alloy molten metal and then quenched to suppress defects caused by gas generation of low melting point elements, while at the same time the average spacing of the branches of the dendritic tissue 10㎛ or less (excluding 0) By controlling to achieve, in the state where the dendritic structure is finely distributed at high density, fine and Ni-Bi-based intermetallic compounds are densely and uniformly accumulated at narrow intervals between the branches of the dendritic tissue, thereby lubricating precipitates. When the specific surface area becomes larger and other metals move in contact with each other, the precipitate is uniformly coated on the alloy surface, so the friction coefficient is lowered, and the peeling of the galling and lubrication alloys on the counter metal seizes. It can be prevented.

Referring to the manufacturing method of the lubricating alloy according to the present invention, after injecting C, Sn, Bi and Se into the melting furnace at 750 ~ 850 ℃ to produce a low melting point ingot, Si, Mn, Ni, Cr, Mo and After the Fe is added to the melting furnace to melt at 1,550 ~ 1,650 ℃ to produce a high melting point ingot.

Then, first, the high melting point ingot is introduced into a melting furnace to dissolve at 1,500 to 1,600 ° C., and then the low melting point ingot is added to reduce the volatilization loss and mix to melt an alloy. Here, the melting furnace may be an electric resistance, a high frequency furnace or the like.

The alloy molten metal is cast in a casting mold, and a method of rapidly cooling at least a portion of an outer circumferential region by a cold body, using a special casting sand, and a conventional cooling method (WET-SAND) is manufactured to manufacture a sliding member for a mechanical device. Charge the sliding member into the heat treatment furnace, vacuum heat treatment at 1,000 ~ 1,200 ℃ and then quench to complete the final product.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the present invention is not limited by these examples.

The low melting point ingot and the high melting point ingot were prepared by using the alloying composition as shown in Table 1, the high melting point ingot was stirred at 1,550 ° C. in a high frequency induction melting furnace, and charged with the low melting point ingot to prepare an alloy melt. After casting, alloy specimens were prepared.

[Table 1]

These specimens were obtained from ASTM spec. Friction test was carried out according to the test method specified in G-99. Friction of the specimen was made by rubbing an alloy specimen processed with a 2 mm diameter pin for 60 minutes on a metal disc (stainless steel 316) rotating at 100 rpm with a load of 20 kg. Surface was observed, and the wear rate per hour (wear rate) was measured and the results are shown in Table 2.

In addition, the corrosion rate was measured after immersing the specimen in a strong sulfuric acid (98%), hydrochloric acid (36%), nitric acid (60%) solution maintained at 50 ℃ for 360 hours, and the Vickers hardness at room temperature was measured. , And measured five times, the average value of the values are shown in Table 2.

The specimen was observed with an optical microscope (OM) to take a photograph, and the gap between the dendritic tissues was measured. The results are shown in Table 2 below.

[Table 2]

As shown in the results of Table 2, the invention alloy with the addition of the Se component is less lubrication characteristics due to the less amount of friction due to friction than the comparative alloys, and the wear rate was also many times better, in particular, the invention alloys 1,3 And 5 is excellent in lubrication characteristics compared to other invented alloys, which is due to the addition of Se alloy which is harmless to human body, densely densified dendritic tissue of the branch spacing is fine and evenly dispersed Ni-Bi-based intermetallic compound Precipitation appears to be due to an increase in the self-lubricating properties of the alloy and a decrease in the friction coefficient.

However, invented alloy 6 had a large amount of abrasion, which is due to the lack of precipitation of Ni-Bi-based intermetallic compounds (NiBi _3, etc.), resulting in poor lubricity compared to other alloy inventions.

In addition, in the sulfuric acid, hydrochloric acid, and nitric acid solution, the corrosion rate of the invention alloy was significantly lower than that of the comparative alloy, and thus the corrosion resistance was also excellent. This invention alloy was further added with alloying elements such as Cr and Mo compared to the comparison alloy. It seems to have excellent corrosion resistance and corrosion resistance.

In addition, the invention alloy exhibits a very good hardness compared to the comparative alloy, which shows a very excellent hardness compared to the comparative alloy without addition of Co and W due to the fine and uniform dispersion and formation of Co and W carbides in the matrix structure. see.

As a result, the self-lubricating alloy of the present invention improves corrosion resistance and low thermal expansion by increasing Mo alloy content in Ni and Cr, and improves high temperature strength and wear resistance by forming Co and W carbides. By densifying and minimizing the dendritic tissue, which is a matrix structure, it increases self-lubricating and finely and uniformly disperses and precipitates Ni-Bi-based intermetallic compounds in such dendritic tissues, resulting in galling and seizing. Since there is no phenomenon and the friction coefficient is also reduced, the service life of the self-lubricating alloy can be obtained which is extended in life and also has various properties.

The present invention is not limited to the above-described embodiments. Anything having substantially the same constitution as the technical idea described in the claims of the present invention and achieving the same operational effect is included in the technical scope of the present invention.

Claims (6)

By weight% C: 0.03-0.1%, Si: 0.1-5.0%, Mn: 0.5-1.5%, Ni: 55-70%, Cr: 3-10%, Mo: 3-8%, Bi: 1-6 Eco-friendly self-lubricating alloy with excellent corrosion resistance and abrasion resistance, consisting of%, Sn: 1-5%, Se: 0.5-3.0%, balance Fe and other unavoidable impurities.
delete The method of claim 1,
Eco-friendly self-lubricating alloy excellent in corrosion resistance and abrasion resistance, characterized by further containing at least one selected from Co: 0.5 to 3.0% and W: 0.5 to 2.0% by weight.
The method of claim 1,
The alloy has a dense and fine dendritic structure and austenite structure, the dendritic structure is an environmentally friendly self-lubricating alloy excellent in corrosion resistance and wear resistance, characterized in that the average spacing of the branches is 10㎛ or less (excluding 0).
5. The method of claim 4,
Eco-friendly self-lubricating alloy excellent in corrosion resistance and wear resistance, characterized in that formed by finely dispersed precipitated Ni-Bi-based intermetallic compound in the interval between the branches of the dendritic structure.
The sliding member for a mechanical apparatus which consists of an environmentally friendly self-lubricating alloy excellent in the corrosion resistance and abrasion resistance of any one of Claims 1-5.