JPS62133028A - Manufacture of self lubricative sintered copper alloy - Google Patents

Abstract

PURPOSE:To manufacture the titled alloy superior in wear resistance and pressing strength, by heating and treating a compact obtd. by mixing copper alloy powder, lubricative powder made of Mo and graphite and synthetic resin binder, then sintering the compact. CONSTITUTION:Mo powder and graphite powder are added as lubricative powder to copper alloy contg. Ni, Sn and P to obtain material powder. Next, compact is formed from mixture of the material powder and synthetic resin binder, held at resin decomposition temp. range of 550-650 deg.C to thermalloy decompose the binder. Powder compact composed of the material powder remaining thereby is held and soaked at 800-<900 deg.C solidus line temp. range, then held and sintered at 900-1,050 deg.C semiliquid phase temp. range. In this way, the titled alloy having superior wear resistance and high compressing strength is obtd. at a high productivity without causing deformation.

Description

DETAILED DESCRIPTION OF THE INVENTION A0 Object of the Invention (1) Field of Industrial Application The present invention relates to a method for manufacturing a self-lubricating sintered copper alloy used for wear plates of press machines and the like.

(2) Conventional technology Conventionally, as a manufacturing method for this type of sintered copper alloy, nickel,
A method of sintering copper-based raw material powder containing tin, phosphorus, and graphite is known (see Japanese Patent Publication No. 58-52547).

(3) Problems to be Solved by the Invention The graphite functions as a lubricant, and in order to fully exhibit its function, a large amount of graphite powder is used in the conventional method.

As a result, there is a problem that the compressive strength of the sintered copper alloy is reduced, and the toughness and therefore the impact resistance of the sintered copper alloy are low due to the chemical components.

Furthermore, since the raw material powder is used in a powdered state,
There are also problems in that it is difficult to handle and interferes with the production efficiency of sintered copper alloys.

In view of the above, the present invention reduces the graphite content, and supplements the M content of graphite with molybdenum, which has lubricating properties and contributes to improving wear resistance, as well as exhibiting the effect of improving toughness, thereby achieving excellent wear resistance. It is an object of the present invention to provide the above-mentioned manufacturing method with good productivity, which makes it possible to obtain a self-lubricating sintered copper alloy having high properties and high compressive strength.

B1 Structure of the Invention (Means for Solving 11 Problems) The present invention consists of a raw material powder and a synthetic resin made by adding molybdenum powder and graphite powder as lubricating powder to a copper alloy powder containing nickel, tin, and phosphorus. Obtaining a molded body from a mixture with a binder; holding the molded body in a resin decomposition temperature range of 550°C or higher and 650°C or lower, thermally decomposing the synthetic resin binder and leaving a powder molded body made of the raw material powder; the step of heating the powder compact to 800°C or higher at 90°C
A step of maintaining the temperature in a solidus temperature range of less than 0° C. for soaking;
It is characterized by using the step of maintaining the powder compact in a semi-phase formation temperature range of 900° C. or more and 1050° C. or less to obtain a sintered copper alloy from the powder compact.

(2) Function Since a mixed powder of molybdenum powder and graphite powder is used as the lubricating powder, the graphite content is reduced in accordance with the molybdenum content, thereby improving the compressive strength and toughness of the sintered copper alloy. It becomes possible to improve the performance.

Further, since the raw material powder is used in the form of a molded body obtained from a mixture of the raw material powder and a synthetic resin binder, the raw material powder can be easily handled.

Furthermore, the synthetic resin binder is thermally decomposed in the resin decomposition temperature range, and the decomposed gas is emitted from between the constituent powders of the raw material powder, resulting in the formation of cavities due to residual gas in the sintered copper alloy and the intrusion of harmful gas components. problems can be reliably avoided. Furthermore, since the thermal decomposition gas of the synthetic resin binder occurs slowly in the above temperature range, the remaining powder compact has approximately the same shape as the above compact, thus suppressing deformation of the powder compact. I can do it.

Furthermore, since the powder compact is uniformly heated in the solidus temperature range,
Local elution of the powder compact during sintering and therefore deformation of the sintered copper alloy can be prevented.

Furthermore, since the powder compact is sintered in the semi-phase temperature range where the liquid phase and solid phase coexist, floating and segregation of graphite does not occur.
Therefore, the lubrication properties of the sintered copper alloy can be made uniform throughout. Furthermore, since the pores between the solid phases are filled with the liquid phase, the density of the sintered copper alloy can be improved.

(3) Embodiment FIG. 1 shows a sliding member 1, which consists of a base material 2 and a self-lubricating sintered copper alloy 3 welded to its negative surface. The sintered copper alloy 3 is welded to the base material 2 during sintering.

The sintered copper alloy 3 is manufactured using a raw material sheet as a molded body obtained from a mixture of raw material powder and a synthetic resin binder.

As raw material powder, nickel 5-30% by weight, tin
Copper alloy powder containing 7 to 13% by weight and 0.3 to 2% by weight of phosphorus, to which 1 to 5% by weight of molybdenum powder and 1 to 2.5% by weight of graphite powder are added as lubricating powder. Applicable.

In this raw material powder, the reason why the blending amount of each chemical component was limited as described above and the role of each chemical component are as follows.

Nickel functions as a brazing material and has the effect of improving the sintering properties of the raw material powder, the adhesion of the sintered copper alloy to the base material, and the strength of the copper matrix, but if its content is less than 5% by weight, the above-mentioned No effect can be obtained, and even if it exceeds 30% by weight, no improvement in the effect can be expected, and furthermore, the cost will increase.

Tin alloys with copper and exhibits the effect of improving the strength and wear resistance of the copper matrix, but if the content is less than 7% by weight, the above effects cannot be obtained, and if the content exceeds 13% by weight, the copper alloy The melting point of the sintered copper alloy decreases, and the shape retention of the sintered copper alloy deteriorates.

Phosphorus precipitates in the copper matrix and has the effect of improving its strength and wear resistance, but when the amount of phosphorus is 0.3
If it is less than 2% by weight, the melting point of the copper alloy will increase and the sinterability of the raw material powder will deteriorate, and if it exceeds 2% by weight, the melting point of the copper alloy will decrease and the shape retention of the sintered copper alloy will deteriorate.

Molybdenum has the effect of strongly bonding with copper alloys and improving the toughness, wear resistance, and lubricity of sintered copper alloys, but if the amount of molybdenum is less than 1% by weight, the above effects cannot be obtained; If it exceeds 5% by weight, it becomes difficult to form the raw material sheet, and the sintering strength and density of the sintered copper alloy decrease.

Graphite has the effect of improving the lubricity of the sintered copper alloy, but if the amount is less than 1% by weight, the above effect cannot be obtained, and if it exceeds 2.5% by weight, it will cause compression of the sintered copper alloy. Strength decreases.

The synthetic resin binder is a thermoplastic synthetic resin emulsion, and the synthetic resin binder is blended in an amount of 1 to 4% by weight based on the raw material powder. The reason for this is that when the amount of synthetic resin binder is less than 1% by weight, the shape retention of the raw material sheet is poor, and the binding force between the raw material powders becomes weak, causing the powder to fall off, whereas when it exceeds 4% by weight. This increases the porosity of the sintered copper alloy, resulting in a decrease in density and deterioration of shape accuracy, and increases residual carbon, which inhibits sinterability and causes poor welding of the sintered copper alloy to the base material. Because it invites you.

Next, a method for manufacturing the sliding member 1 will be explained with reference to FIGS. 2 and 3.

i. 25% by weight of nickel, tin obtained by the spraying method for manufacturing raw material sheets.
Copper alloy powder consisting of 10% by weight, phosphorus 1.1ffl% and the balance copper, with a particle size that can pass through a standard sieve of 110 mesh. 92% by weight, obtained by mechanical grinding, that can pass through a standard sieve of 270 mesh. Raw material consisting of 2.5% by weight of molybdenum powder with a particle size that can pass through a standard sieve of 28 mesh but not 65 mesh, obtained by mechanical grinding. The powder was mixed with 3% by weight of a synthetic resin binder made by mixing a tetrafluoroethylene resin and an acrylic resin at a ratio of 1:1 and adding 50% by weight of water to the mixed resin to form an emulsion, as shown in Figure 2 ( As shown in al., they are put into a kneader 4 and mixed for 3 minutes to obtain a mixture M in which the raw material powder is uniformly dispersed in a synthetic resin binder.

As shown in FIG. 2(b), the mixture M is transferred onto the heater 5 and heated to 80 to 150°C to evaporate water and dry it.

As shown in FIG. 2 (C1), the heated mixture M is passed through the roll machine 6 several times to obtain a raw material sheet S having a thickness of 2 to 3 fins.

As shown in FIG. 2 (dl), the raw material sheet S is transferred onto the heater 5 and heated at 80 to 120"C for 30 minutes to remove distortion during roll forming.

The density of the raw material sheet S is 4.8 g/cm', and
It is stored by rolling it into a roll as shown in 1.

ii. Manufacture of sliding member As shown in Figure 2 (fl), 200 mm
Cut a raw material board P with a width of 200 fins, and cut the raw material board P into a JTS 5S4 with a length of 200 nm, a width of 2000 nm, and a thickness of 19 fins.
It is attached to the upper surface of the steel plate base material 2 represented by 1 using acrylic adhesive, and the upper surface is
It is covered with a breathable degassing sheet 6 made of ceramic fiber (trade name Kao Wool) with a thickness of 211 mm and a thickness of 211 mm, and is further covered with a gas venting sheet 6 having a length of 200 M and a width of 2 mm on the top surface of the sheet 6.
A pressurizing body 7 made of the same material as above and having a thickness of 38 mm and a thickness of 38 mm is placed.

The pressurizing body 7 is used to press the raw material powder during sintering to improve the density of the sintered copper alloy 3, but if this pressurizing body 7 is placed directly on the raw material plate P, the synthesis The degassing performance of the decomposed gas generated from the resin binder and the like is poor, and the raw material powder on the outer periphery of the raw material plate P that has lost its binding strength is scattered by the ejection pressure of the decomposed gas. Therefore, the sheet 6, which is larger than the raw material plate P, is interposed between the pressurizing body 7 and the raw material plate P, and a gas discharge path is formed using its breathability.
It also prevents the raw material powder from scattering. In order to fully achieve this purpose, the size of the raw material plate P and the sheet 6 must be
There is a correlation between the thickness of For example, if the thickness of the raw material plate P is 2 mm, and its size is 80 mm long and 80 mm wide, the thickness of the sheet 6 is 1 wm, 200 wm long, and 200 mm wide.
In the fin, the thickness of the sheet 6 is 2 mm. In addition, when the size of the raw material plate P having the above-mentioned thickness is less than 60 x 1 x 60 x 1 x 60 x 1, and when the thermal decomposition of synthetic resin binder etc. is extremely slow, the decomposition gas will not be released even without the sheet 6. Degassing is easy, and the raw material powder does not scatter.

The degassing sheet 6 is required to have non-adhesive properties to the powder and the pressurizing body 7 at the sintering temperature of the raw material powder. Materials that meet this requirement include asbestos, rock wool, and the like, in addition to the ceramic fibers. In addition, when the sheet 6 is not used, a mold release agent is applied to the pressurizing body 7 in order to prevent the pressurizing body 7 from fusing to the raw material powder. A method such as interposing a ceramic body such as the like is adopted.

The laminate was placed in a vacuum sintering furnace 8, and the synthetic resin binder and acrylic adhesive were thermally decomposed, the raw material powder was sintered, and the sintered copper alloy was welded to the base material under the heating conditions shown in FIG. conduct. Nitrogen gas is used as a carrier gas, and the degree of vacuum is 1 Torr.

+a) First heating zone (FIG. 3 AI) This heating zone A is from room temperature to 600°C. The temperature increase rate from room temperature was 20°C/min, and the inside of the furnace was maintained at a constant temperature of 600°C for 60 minutes.

In this heating zone A, the moisture in the laminate is first evaporated, and then the tetrafluoroethylene resin, acrylic resin, and acrylic adhesive in the synthetic resin binder are heated in the resin decomposition temperature range of 560°C to 600°C. Decomposed and gasified. The decomposed gas is discharged from between the constituent powders of the raw material powder through the sheet 6, leaving behind a powder compact. In this resin decomposition temperature range, the resin component decomposes slowly, so that the shape of the powder compact hardly changes. Furthermore, the sorting 6 prevents the raw material powder that has lost its bonding strength from scattering around the outer periphery of the base material 2.

(b) Second heating zone (Fig. 3 A Riko's heating zone A2 has a temperature of 800°C or more and less than 900°C. The temperature increase rate from the first heating zone A1 is 20°C/min, and the temperature inside the furnace is 800°C or higher and lower than 900°C.
It is maintained at a constant temperature for 30 minutes at a temperature of .degree. C. or more and less than 900.degree. In this heating zone A2, the powder compact and the base material 2 are uniformly heated in the solidus temperature range of the powder compact.

This heat treatment promotes the bonding between the raw material powders, so that the powder compact becomes a pre-sintered state and has good shape retention.

(C) Third heating zone (A3 in FIG. 3) The temperature in this heating zone A3 is 900'C or more and 1050C or less. The temperature increase rate from the second heating zone A2 is 10'C
/min, and the inside of the furnace is maintained at a constant temperature for 30 minutes at a temperature of 900° C. or more and 1050° C. or less.

This heating zone A3 is a process phase temperature range where a solid phase and a liquid phase coexist in the raw material powder, and the liquid phase fills the pores between the solid phases, and the pressure of the pressurizing body 7 prevents the liquid phase from flowing. The sintering progresses and a sintered copper alloy 3 with high density is obtained. At the same time, the sintered copper alloy 3 is welded to the base material 2.

In this case, nickel is alloyed with phosphorus, and its function as a brazing material ensures that the sintered copper alloy 3 is welded to the base material 2.

In this heating zone A, the flow of the liquid phase in the raw material powder is slow, so floating and segregation of graphite does not occur, and therefore the lubricity of the sintered copper alloy is uniform throughout.

(di cooling zone (Fig. 3B) Nitrogen gas is introduced into the vacuum sintering furnace 8 until the internal pressure reaches 50011 mHg, and the nitrogen gas is circulated by a cooling fan to cool the sintered copper alloy 3 and the base material 2. etc. to cool down.

The sliding member l shown in FIG. 1 is obtained through the heating and cooling process described above.

Sintered copper alloy 3 had a density of 6.3 g/cm 3 , a Rockwell hardness of HMI 335 or higher, and a porosity of 13%, and no chipping occurred on the outer periphery.

The sliding member 1 was subjected to mechanical processing and oil impregnation treatment, and then used as a wear plate of a press machine, and a functional test was conducted, and the results shown in Table 1 were obtained. In the table, A corresponds to the sliding member obtained through the above process, and B corresponds to a sliding member obtained by embedding graphite in cast iron as a comparative example.

In addition, in the mating shrine, the cast iron ten graphite has the same structure as Comparative Example B.

Table 1 As is clear from Table 1, sliding member A has approximately the same wear resistance as Comparative Example B (iiff) and excellent sliding properties.

Table ■ shows that the blending amounts of molybdenum powder (Mo) and graphite powder (G) were varied in copper alloy powder containing 28.7% by weight of nickel, 8.5% by weight of tin, and 0.63% by weight of phosphorus. A raw material sheet is manufactured in the same manner as described above using raw material powder, and the raw material sheet cut from the raw material sheet is
The Rockwell hardness HRB of a sintered copper alloy obtained by vacuum sintering under sintering conditions of heating at 40° C. for 20 minutes is shown.

Table 2 As is clear from Table n, the hardness of the sintered copper alloy improves as the graphite content decreases, and the hardness improves as the molybdenum content increases at the same graphite content. This improves the wear resistance of the sintered copper alloy.

FIG. 4 shows the compressive strength of the sintered copper alloy, and it is clear that this compressive strength is independent of the molybdenum content and decreases with increasing graphite content. The compressive strength required for sliding parts such as press wear plates is 17 to 2.
5 kg/n'', and in order to satisfy this, it is necessary to set the graphite content to 1 to 2.5% by weight.

C1 Effects of the Invention According to the present invention, since a mixed powder of molybdenum powder and graphite powder is used as the lubricating powder, the graphite content can be reduced in accordance with the molybdenum content. It is possible to obtain self-lubricating sintered copper alloys with good wear resistance, which have excellent compressive strength due to the reduction of , and also have improved toughness and therefore impact resistance properties based on the addition of molybdenum.

Further, since the raw material powder is used in the form of a molded body obtained from a mixture of the raw material powder and the synthetic resin binder, the raw material powder can be easily handled and the production efficiency of the sintered copper alloy can be improved. In this case, the synthetic resin binder is thermally decomposed in the resin decomposition temperature range, and the decomposed gas is emitted from between the constituent powders of the raw material powder, resulting in the formation of cavities due to residual gas in the sintered copper alloy, and the removal of harmful gas components. Problems such as intrusion can be reliably avoided. Furthermore, since thermal decomposition of the synthetic resin binder occurs slowly in the above temperature range, the powder compact left behind has approximately the same shape as the compact, and therefore deformation of the powder compact can be suppressed. can.

Furthermore, since the powder compact is uniformly heated in the solidus temperature range,
Local elution of the powder compact during sintering and therefore deformation of the sintered copper alloy can be prevented.

Furthermore, since the powder compact is sintered in the semi-phase temperature range where the liquid phase and the same phase coexist, floating and segregation of graphite does not occur.
Therefore, the lubrication properties of the sintered copper alloy can be made uniform throughout. Furthermore, since the pores between the solid phases are filled with the liquid phase, the density of the sintered copper alloy can be improved.

[Brief explanation of drawings]

Figure 1 is a perspective view of the sliding member, Figure 2 is an explanatory diagram of the manufacturing process of the sliding member, Figure 3 is a graph showing the relationship between time and temperature in the sintering process, and Figure 4 is a graph showing the relationship between time and temperature in the sintered copper alloy. It is a graph showing the relationship between graphite content and compressive strength. S...Raw material sheet as a compact, 3...Sintered copper alloy patent applicant Honda Motor Co., Ltd. Figure 2 (a) (b) (f) No. (d)

Claims (1)

[Claims] Copper alloy powder containing nickel, tin and phosphorus,
A step of obtaining a molded body from a mixture of a raw material powder obtained by adding molybdenum powder and graphite powder as lubricating powder and a synthetic resin binder;
A step of thermally decomposing the synthetic resin binder and leaving a powder molded body made of the raw material powder while maintaining the resin decomposition temperature in the following resin decomposition temperature range; holding the powder compact in a semi-liquid temperature range of 900°C or more and 1050°C or less to obtain a sintered copper alloy from the powder compact; A method for producing a self-lubricating sintered copper alloy.