JP2010265500A - High-tensile brass alloy for sliding member and sliding member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-tensile brass alloy for a sliding member having excellent wear resistance, which has a structure where the β single phase structure of the basal phase is maintained, and further, an Fe-Cr-Si base intermetallic compound is dispersed into the β phase, and to provide a sliding member using the high-tensile brass alloy. <P>SOLUTION: The high-tensile brass alloy for a sliding member has a composition comprising, by mass, 17 to 28% Zn, 3 to 10% Al, 1 to 4% Fe, 0.1 to 4% Cr and 0.5 to 3% Si, and the balance Cu with inevitable impurities, and has a structure where a basal phase shows a β single phase structure and, further, an Fe-Cr-Si base intermetallic compound is dispersed into the β phase. By the use of the alloy, hardness increases, and further, wear resistance as that of a sliding member improves. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a high-strength brass alloy having excellent wear resistance, and in particular, a high-strength brass alloy suitable for use in sliding members such as a slide bearing and a sliding plate, and a slide using the high-strength brass alloy. The present invention relates to a moving member.

  Conventionally, high-strength brass alloys used for sliding applications such as bearings include high-strength brass castings 1 to 4 specified in Japanese Industrial Standard JISH5120 (see Non-Patent Document 1). These high-strength brass alloys have improved seawater resistance, toughness, wear resistance and hardness by adding elements such as Al, Fe, and Mn to Cu-Zn alloys. It is widely used for sliding applications such as used synchronizer rings, gears for general machines, and bearings.

  In a high-strength brass alloy, various matrix phases such as α phase, β phase, α + β phase, and γ phase appear according to the zinc equivalent of the additive element. When the zinc equivalent is low, an α phase appears. The high-strength brass alloy in which the α phase appears is excellent in toughness but low in hardness, and therefore, when used in sliding applications, it tends to cause abrasive wear. Further, when the zinc equivalent is increased, a β phase appears, and when the zinc equivalent is further increased, a γ phase is exhibited. A high-strength brass alloy in which the γ phase has appeared has the advantage that the hardness is increased and the wear resistance is improved, but the toughness is remarkably lowered and the impact resistance is lowered.

  Therefore, in sliding applications, a high-strength brass alloy whose parent phase is a single phase of β phase is widely used because it has excellent wear resistance without a reduction in toughness. However, with the recent increase in efficiency and life of mechanical devices, there is a demand for further improvement in wear resistance of sliding members made of high-strength brass alloys.

For the purpose of improving the wear resistance of high strength brass alloys whose matrix is α + β phase or β phase structure, high strength brass alloy in which manganese silicide based intermetallic compounds such as Mn ₅ Si ₃ are dispersed in the matrix ( For example, refer to Patent Document 1) and high-strength brass alloys (for example, refer to Patent Document 2 and Patent Document 3) in which an intermetallic compound composed of an Fe-Mn-Si intermetallic compound is dispersed in a matrix. ing.

Japanese Industrial Standard JISH5120

Japanese Patent Publication No.51-41569 Japanese Patent Publication No.62-57700 Japanese Patent Publication No. 2-38651

  Although it is known that manganese silicide and Fe—Mn—Si intermetallic compounds are dispersed in the matrix phase, it is known that the wear resistance is improved. However, the zinc equivalent of Si is 10, and high strength is achieved. It is extremely high among the additive elements of brass alloys. Therefore, since the zinc equivalent is increased by adding Si, the addition amount of other elements is restricted in order to maintain the matrix phase in a single-phase structure of β phase. Here, for example, Al is known as another element. Al is an element that improves the corrosion resistance and strengthens the parent phase. However, since the zinc equivalent of Al is as high as 6, an γ phase appears in the parent phase when the amount of addition increases. For this reason, when Al is added together with the above-described Si, the zinc equivalent increases, and a γ phase is generated in the parent phase. As a result, the wear resistance is improved, but the elongation is significantly reduced. For this reason, even if it tried to improve the wear resistance by adding Si, the amount of Al added had to be reduced, and it was difficult to improve the wear resistance while maintaining a single structure of β phase. .

As a result of intensive studies in view of the above circumstances, the present inventors focused on Cr as an element that improves corrosion resistance and generates an intermetallic compound between Fe and Si in the components of a high-strength brass alloy. A high-strength brass alloy to which Cr is added at a predetermined ratio confirms that the parent phase maintains a single-phase structure of the β phase and that the Fe—Cr—Si intermetallic compound is dispersed and precipitated in the β phase. It has been found that the corrosion resistance and wear resistance of a high-strength brass alloy can be further improved.
The present invention has been made on the basis of the above findings, and the object of the present invention is to maintain a single-phase structure of the β phase of the parent phase and a structure in which the Fe—Cr—Si intermetallic compound is dispersed in the β phase. An object of the present invention is to provide a high-strength brass alloy for a sliding member having excellent wear resistance and a sliding member using the high-strength brass alloy.

The high-strength brass alloy for sliding members of the present invention for achieving the above object is
(1) By mass ratio, Zn in the range of 17% to 28%, Al in the range of 3% to 10%, Fe in the range of 1% to 3%, 0.1% to 4% Cr in the following range, Si in the range of 0.5% or more and 2% or less, the balance is made of Cu and inevitable impurities,
(2) The parent phase exhibits a β-phase single phase structure and a structure in which an Fe—Cr—Si intermetallic compound is dispersed in the β phase.

Further, the sliding member of the present invention for achieving the above object is
(3) A plurality of holes or grooves are formed on at least an inner peripheral surface as a sliding surface of a cylindrical body made of the high-strength brass alloy for sliding members according to (1) and (2). Alternatively, a solid lubricant such as graphite is embedded and fixed in the groove.

Here, the other sliding member of the present invention for achieving the above object is:
(4) A plurality of holes, grooves or recesses are formed on the surface as the sliding surface of the plate-like body made of the high strength brass alloy for the sliding portion seat described in (1) and (2) above. A solid lubricant such as graphite is embedded and fixed in the hole, groove or recess.

further,
(5) It is preferable that the area ratio which the solid lubricant occupies in the internal peripheral surface or surface as said sliding surface exists in the range of 10% or more and 40% or less.

  According to the present invention, the matrix phase exhibits a β phase single phase structure, and the β phase exhibits a structure in which a hard Fe—Cr—Si intermetallic compound is dispersed. Therefore, hardness is increased and wear resistance is increased. Can further improve the high-strength brass alloy for sliding members and a sliding member using the high-strength brass alloy.

It is a top view of the plate-shaped sliding member of embodiment of this invention. It is sectional drawing of the cylindrical sliding member of embodiment of this invention. It is sectional drawing of the other example of the cylindrical sliding member of embodiment of this invention. It is a perspective view which shows the test method of the abrasion loss in an Example.

  Next, the present invention and its embodiments will be described in more detail. Needless to say, the present invention is not limited to these embodiments.

  The high-strength brass alloy for sliding members of the present invention has a mass ratio of Zn: 17 to 28%, Al: 3 to 10%, Fe: 1 to 4%, Cr: 0.1 to 4%, Si: 0 0.5 to 3%, the balance being Cu and inevitable impurities. Hereinafter, the component composition of the high-strength brass alloy of the present invention will be described.

  Zn is an element that determines the structure of the mother phase while imparting strength, wear resistance, impact resistance and corrosion resistance to the lubricating oil of the mother phase. Depending on the amount of Zn added, phases such as α phase, β phase, and γ phase appear in the matrix structure. The amount of Zn added differs depending on the zinc equivalent of the other additive elements and the amount added, but if the amount added is less than 17% by mass, an α phase appears in the structure of the parent phase and the wear resistance deteriorates. If the amount exceeds 28% by mass, a γ phase appears in the matrix structure and the alloy becomes brittle. Therefore, the addition amount of Zn is 17 to 28% by mass.

  Al is an element that promotes the formation of β phase and is effective in strengthening the matrix and increasing the hardness. Like Si, it has a large zinc equivalent and promotes the formation of a γ phase structure. In addition to being able to obtain sufficient hardness necessary for the properties, the matrix phase cannot be sufficiently strengthened, and a γ-phase structure added in excess of 10% by mass is formed and the alloy becomes brittle. Therefore, the addition amount of Al is 3 to 10% by mass, preferably 4 to 6% by mass.

  Fe combines with Si and Cr, which will be described later, to precipitate hard Fe—Cr—Si intermetallic compounds, thereby improving the wear resistance. If the addition amount is less than 1% by mass, not only the precipitation amount of Fe—Cr—Si intermetallic compound is small and the effect of improving the wear resistance is not sufficiently exhibited, but also the refinement of the alloy structure is impaired and the mechanical properties are reduced. There is a risk of lowering. Moreover, when it exceeds 4 mass%, the precipitation amount of a Fe-Cr-Si type | system | group intermetallic compound will increase, and on the contrary, abrasion resistance will be reduced. Therefore, the added amount of Fe is 1 to 4% by mass.

  Cr combines with the Fe and Si described later to precipitate a hard Fe—Cr—Si intermetallic compound and contributes to improvement of wear resistance. If the addition amount is less than 0.1% by mass, it does not contribute to the improvement of wear resistance, and if it exceeds 4% by mass, it may cause deterioration of machinability and castability. Therefore, the addition amount of Cr is 0.1 to 4% by mass.

  Si combines with the Fe and Cr to precipitate a hard Fe—Cr—Si intermetallic compound and contributes to the improvement of wear resistance. If the addition amount is less than 0.5% by mass, it does not contribute to the improvement of the wear resistance, and if it exceeds 3% by mass, the γ phase may appear and the wear resistance may be deteriorated. Therefore, the addition amount of Si is 0.5-3 mass%.

  The high-strength brass alloy of the present invention is cast into a plate shape to form a plate-like body, and one surface of the plate-like body is used as a sliding surface to form a plurality of holes or grooves on the surface. A solid lubricant embedded sliding member in which a solid lubricant such as graphite is embedded and fixed in the groove can be obtained.

  FIG. 1 is a plan view showing a sliding member (sliding plate) 1 in the form of a plate using the high-strength brass alloy of the present invention. A plurality of recesses 4 that are recessed in the thickness direction are formed on one surface (sliding surface) of the high strength brass alloy sliding member base 2. The concave portion 4 is formed so that the total area of the openings in the area of the surface of the sliding member base 2 is 10 to 40%. The concave portion 4 is filled and held with a solid lubricant 5 such as graphite. In order to make the wear resistance of the base 2 and the solid lubricant 5 good, the area of the surface 3 of the sliding member base 2 is reduced. At least 10% of the total area of the openings of the recessed portions 4 is required. However, if the total area of the openings of the recesses 4 occupying the area of the surface of the sliding member base 2 exceeds 40%, the strength of the sliding member base 2 is reduced.

  The concave portion 4 is filled and held with a solid lubricant 5 such as graphite. In order to exhibit the wear resistance of the base 2 and the solid lubricant 5 satisfactorily, the total area of the surface of the sliding member base 2 is set. At least 10% of the total area of the openings of the recessed portions 4 is required. However, if the total area of the openings of the recesses 4 occupying the area of the surface of the sliding member base 2 exceeds 40%, the strength of the sliding member base 2 is lowered. The recess 4 is formed by drilling or cutting using a drill or end mill, but may be formed by other means.

  The solid lubricant 5 filled and held in the plurality of recesses 4 formed on the surface of the sliding member base 2 is such that adjacent solid lubricants 5 overlap each other in one direction or two orthogonal directions (overlap: over). It is preferable that they are arranged so as to have a lap margin δ).

  FIG. 1 shows an example in which adjacent solid lubricants 5 filled and held in a plurality of recesses 4 formed on the surface of a sliding member base 2 are arranged so as to overlap each other in two orthogonal directions.

  Further, the high-strength brass alloy of the present invention is cast into a cylindrical shape to form a cylindrical body, and a plurality of holes or grooves are formed on at least an inner peripheral surface as a sliding surface of the cylindrical body. A solid lubricant embedded sliding member in which a solid lubricant such as graphite is embedded and fixed in the groove can be obtained.

  FIG. 2 is a cross-sectional view showing a sliding member (cylindrical bearing) 1a in the form of a cylindrical bush using the high-strength brass alloy of the present invention. On the inner peripheral surface (sliding surface) 3a of the sliding member base 2a made of high-strength brass alloy, a plurality of ring-shaped grooves 4a arranged along the longitudinal direction are formed. Similar to the sliding member 1, the groove 4a is formed such that the total area of the openings of the ring groove 4a occupying the area of the inner peripheral surface 3a of the sliding member base 2a is 10 to 40%. Is done. The reason for this ratio is also the same reason as the above 10 to 40%. The groove 4a is formed by cutting using a cutting tool or the like, but may be formed by other means.

  FIG. 3 is a cross-sectional view showing a sliding member 1b in the form of a cylindrical bush using the high-strength brass alloy of the present invention. The sliding member 1b is formed with a cylindrical sliding member base 2b and a plurality of columnar holes 4b communicating with the inner peripheral surface (sliding surface) 3b and the outer peripheral surface. Is filled with a solid lubricant 5 such as graphite. As with the sliding member 1, the holes 4b are formed such that the total area of the openings occupying the area of the inner peripheral surface 3b of the sliding member base 2b is 10 to 40%. The reason for this ratio is also the same reason as the above 10 to 40%. The hole 4b is formed by drilling using a drill or the like, but may be formed by other means.

  The solid lubricant 5 is embedded and fixed in a hole 4b formed so that adjacent solid lubricants 5 overlap each other in the axial direction, or the solid lubricant 5 is adjacent to each other in the circumferential direction. The solid lubricant 5 is embedded and fixed in the hole 4b formed so as to overlap each other, or the solid lubricant 5 is embedded and fixed in the hole 4b formed so that adjacent solid lubricants 5 overlap each other in the axial direction and the circumferential direction. Preferably it is done.

  FIG. 3 shows that the solid lubricant 5 filled and held in a plurality of holes 4b formed in the cylindrical sliding member base 2b is overlapped (overlapped) with each other in the axial direction and the circumferential direction of the base 2b. : An example in which the overlap margin δ) is arranged.

  Next, the present invention will be described in detail based on examples. Needless to say, the present invention is not limited to the following examples.

  (1) Examples 1-5 and Comparative Examples 1-2

  The electrolytic Cu, Zn, Al, Cu—Fe master alloy, Si—Cu master alloy, Cu—Cr master alloy, and Fe—Al master alloy were melted in a low frequency melting furnace so that the chemical components in Table 1 were obtained. After casting into a sand mold having an inner diameter of 50 mm, an outer diameter of 80 mm, and a length of 100 mm at a molten metal temperature of ℃ or higher, machining was performed to prepare a cylindrical bearing having an inner diameter of 60 mm, an outer diameter of 75 mm, and a length of 50 mm. . In the obtained cylindrical bearing, a plurality of through holes having a diameter of 10 mm are formed in the thickness direction on the inner peripheral surface so that the opening area is 30% of the area of the inner peripheral surface, and the through holes are made of graphite. A solid lubricant was embedded. Next, the solid lubricant part was vacuum impregnated with lubricating oil, and this was used as a test piece for wear test. Moreover, the hardness (Brinell hardness) measured the high strength brass alloy part of the test piece for abrasion tests.

  (2) Comparative Examples 3-4

  Low frequency melting of electrolytic Cu, Zn, Al, Cu—Fe master alloy, Ni—Al master alloy, Si—Cu master alloy, Mn—Cu master alloy, Fe—Al master alloy so as to be the chemical components in Table 1 After melting in a furnace and casting into a sand mold having an inner diameter of 50 mm, an outer diameter of 80 mm, and a length of 100 mm at a molten metal temperature of 1100 ° C. or higher, a cylindrical body is formed and machined to give an inner diameter of 60 mm, an outer diameter of 75 mm, and a length of 50 mm. A cylindrical bearing was produced. Thereafter, a test piece for wear test was produced in the same manner as in the above example. Moreover, the hardness (Brinell hardness) measured the high strength brass alloy part of the test piece for abrasion tests.

  Table 2 shows the mechanical properties (Brinell hardness) and wear amount of the cylindrical bearings obtained in the above examples and comparative examples. The wear amount of the test piece for wear test in Table 2 is shown in FIG. It was performed by a journal swing test schematically shown. The test method was performed by swinging and rotating the rotating shaft (mating material) B with respect to the cylindrical bearing A of the above-described examples and comparative examples. The rotating shaft B was rocked and rotated at a constant sliding speed, and the wear amount (μm) of the cylindrical bearing A and the rotating shaft B after a predetermined test time was measured. The test conditions are as follows.

  (3) Test conditions

  Sliding speed 0.47m / min

Surface pressure 1000kgf / cm ² (98MPa)

  Test time 100 hours

  Motion form Oscillating motion

  Swing angle ± 45 °

  Mating material Carbon steel for machine structure (S45C)

Lubrication condition Lithium grease is applied to the sliding surface at the start of the test.

  The high-strength brass alloy according to the examples of the present invention exhibits a single phase structure in which the parent phase is a β phase and a structure in which hard Fe—Cr—Si intermetallic compounds are dispersed in the β phase. Thereby, the high-strength brass alloy of the examples is excellent in wear resistance. In a solid lubricant embedded sliding member in which a solid lubricant is embedded in this high-strength brass alloy, the excellent wear resistance of the high-strength brass alloy as the base metal and the low friction property of the solid lubricant are compatible. On the other hand, it was confirmed that it exhibited excellent wear resistance as a bearing.

  On the other hand, in the high-strength brass alloy of Comparative Example 1, the parent phase exhibited an α + β phase, the hardness was low, and the wear amount of the bearing itself was large. The high-strength brass alloy of Comparative Example 2 exhibited a β + γ phase as a parent phase, and had high hardness and little wear on the bearing itself, but on the other hand, the damage to the mating material was great and the mating material was worn. The high-strength brass alloy of Comparative Example 3 has a single-phase structure in which the parent phase is β-phase, but the intermetallic compound dispersed in the β-phase is an Fe—Cu—Al-based intermetallic compound, and is a solid lubricant. It can be seen that the sliding member embedded with is increased in its wear amount and inferior in wear resistance. Furthermore, the high-strength brass alloy of Comparative Example 4 has a remarkable decrease in wear resistance despite the fact that the Fe—Mn—Si intermetallic compound is dispersed in the matrix phase. Is considered to be due to a small amount of Zn added and a parent phase in which an α phase appears in the β phase.

  As described above, the high-strength brass alloy of the present invention has a single-phase structure in which the parent phase is β-phase and a structure in which hard Fe—Cr—Si intermetallic compounds are dispersed in the β-phase. Wear resistance has been improved. Therefore, the high-strength brass alloy of the present invention can be applied to sliding applications such as sliding bearings, washers and sliding plates.

DESCRIPTION OF SYMBOLS 1, 1a, 1b Sliding member 2, 2a, 2b Sliding member base | substrate 3, 3a, 3b Sliding surface 4 Recessed part 4a Groove 4b Hole 5 Solid lubricant

Claims (4)

  Zn in a range of 17% to 28% by mass, Al in a range of 3% to 10%, Fe in a range of 1% to 4%, a range of 0.1% to 4% Cr, Si within the range of 0.5% or more and 3% or less, the balance is made of Cu and inevitable impurities, the parent phase exhibits a single-phase structure of β-phase, and the β-phase is Fe-Cr-Si-based A high-strength brass alloy for a sliding member characterized by exhibiting a structure in which an intermetallic compound is dispersed.   A plurality of holes or grooves are formed on at least an inner peripheral surface as a sliding surface of the cylindrical body made of the high-strength brass alloy for sliding members according to claim 1, and a solid lubricant is embedded in these holes or grooves. A sliding member characterized by being fixed.   A plurality of holes, grooves or recesses are formed on the surface as a sliding surface of the plate-like body made of the high strength brass alloy for the sliding part seat according to claim 1, and a solid is formed in these holes, grooves or recesses. A sliding member in which a lubricant is embedded and fixed.   The sliding member according to claim 2 or 3, wherein an area ratio of the solid lubricant on the inner peripheral surface or the surface as the sliding surface is in a range of 10% to 40%.

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