JPS60181206A - Method for forming sintered layer on surface of metallic base body - Google Patents

Abstract

PURPOSE:To permit easy venting of the gas generated in the stage of sintering and to prevent the bulging, recessing, etc. to be generated in the sintered layer by adhering a laminated body superposed with a low melting powder sheet and a high melting powder sheet to the surface of a metallic base body. CONSTITUTION:A pressure-sensitive adhesive agent consisting of an acrylic resin is kneaded with alloy powder of a low m.p. having wear resistant to form a low melting powder sheet 2. A pressure-sensitive adhesive agent consisting of an acrylic resin is kneaded with metallic powder of a high m.p. to form a high melting powder sheet 3. The sheet 3 and the sheet 2 are superposed and adhered to form a laminated body 4. The sheet 3 surface of the laminated body 4 is adhered to the surface of a metallic base body 1 and is heated for >=5min at 150-80 deg.C in a non-oxidative atmosphere. The sheet 2 is sintered in a liquid phase onto the sheet 3 in a solid state.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for forming a sintered layer on the surface of a metal substrate.

(Prior art) Conventionally, a powder alloy sheet is adhered to the surface of a metal substrate where wear resistance is required, and then this powder alloy sheet is heated and sintered to obtain a wear-resistant sintered layer. The technology is
It is well known as seen in Japanese Patent Publication No. 53-19540.

However, in this method of sintering powder alloy sheets,
When a powder alloy sheet is adhered to the lower surface, inclined surface, curved surface, etc. of a metal substrate, the sheet will reliably adhere to the surface of the metal substrate even during the process of heating to a high temperature of about 1000°C, which is the sintering temperature. There is a possibility that the adhesion strength required for the product may not be obtained.

On the other hand, the patent application No. 57-1931 previously proposed by the applicant
The powder alloy sheet disclosed in the specification of No. 125 is characterized by the fact that the adhesive mixed in the powder alloy sheet or the adhesive for adhering the powder alloy sheet to the metal substrate is burned out during heating and sintering. The gas may cause defects such as dents or bulges in the sintered layer.

That is, as the sintering process is shown in order in FIGS. 6A-D,
Powder alloy sheets 1 to S made by kneading alloy powder and a synthetic resin adhesive are adhered to the surface of the metal substrate M using adhesive P (see Fig. 6A), and then heated to about 1100°C. Heat treated to sintering temperature. In the process of raising the temperature to this sintering temperature,
At a temperature of about 1050°C, the powder alloy sheet 1~ as shown in Figure 6B.
The surface of S melts and exhibits a liquid phase e, and as gas is generated from this state, the powder alloy sheet S
When a bulge f is formed in a part of the sintered layer and this trapped gas breaks the liquid phase e and ejects, the part in question is in the liquid phase as shown in Figure 6 on the surface of the sintered layer after sintering is completed. Conversely, the movement leaves a defect as a dent d. Further, if the sintering is completed without tearing the fold f, a protrusion remains on the surface, resulting in a problem that the bonding between the sintered layer and the metal base M becomes insufficient.

When the cause of the above phenomenon was investigated, it was found that it was caused by gas generation due to thermal decomposition of the adhesive and the resin component of the adhesive, even at high temperatures near the sintering temperature. In other words, when a powder alloy sheet]- is bonded to a metal substrate and heated and sintered as described above, the adhesive and the low boiling point components of the adhesive gasify and volatilize from around 300°C.
At around 0℃, high boiling point component gas begins to be generated, and at 900℃
When the temperature rises to a certain level, almost no gas is generated, and when the temperature rises to about 1050℃, a liquid phase is generated as described above, and gas is generated again. The presence of the gas prevents it from passing through the powder alloy sheet and traps it between the gold RM body and the sheet, and the generated gas increases the internal pressure to lift the powder alloy sheet and cause it to swell.

The above phenomenon was discovered from the results of gas chromatograph measurements of gas generation accompanying heating of the adhesive to the sintering temperature. The measurement results are shown in Figure 7, and the analytical method used a gas chromatograph equipped with a pyrolysis device.A predetermined amount of sample (acrylic resin adhesive, sample amount 2
4.11 mg) and heated at 300℃, 600℃, 900℃
Heating was repeated for 5 minutes at each temperature in order of 1050°C and 1050°C, and the generated gas was collected using N2 gas as a carrier gas and analyzed and measured.

As seen in the results in Figure 7, low-boiling component gas was generated at 300°C, high-boiling component gas was generated at 600°C, and almost no gas generation was observed at 900°C. At 1050° C., gas from the remaining organic components is generated as tar pitch. In the vicinity of this temperature of 1050°C, the powder alloy sheet begins to exhibit a liquid phase and sintering occurs from the surface, blocking the escape of gases generated from the adhesive and the adhesive of the powder alloy sheet 1~. The sheet swells because gas accumulates between it and the metal substrate.

Then, the gas in this swollen portion expands and tears the sheet, and then the sheet portion becomes depressed. If there are dents on the surface, the thickness of the sintered layer will not be uniform, so there will be a lot of processing costs, and the monthly rate of the powder alloy sheet will be more than 40%, and since the sintered layer is a hard layer, However, it also has problems that require time.

(Object of the Invention) In view of the above circumstances, the present invention provides the necessary adhesive force between the powder sheet and the base material even at high temperatures exceeding the burnout temperature of synthetic resin and reaching the sintering temperature of metals. , a metal base that allows the gas generated when the adhesive or adhesive of the powder sheet burns out to escape easily, and prevents defects such as swelling or dents from occurring in the sintered layer. The object of the present invention is to provide a method for forming a sintered layer on a surface.

(Structure of the Invention) The sintered layer forming method of the present invention comprises a low melting point powder sheet formed by kneading a wear-resistant, low melting point alloy powder with an adhesive made of acrylic resin, and a high melting point metal powder sheet. and a high melting point powder sheet formed by kneading an adhesive made of acrylic resin, and the high melting point powder sheet is arranged so that the high melting point powder sheet has a joint surface with the low melting point powder sheet and a surface open to the atmosphere. and low melting point powder sheet 1~ are superimposed and adhered to form a laminate, the laminate is adhered to the surface of a metal substrate, and then the laminate is heated at a temperature of 150 to 380°C under a non-oxidizing atmosphere. After heating and holding for 5 minutes or more, at least the high melting point powder sheet is in a solid phase state, and the low melting point powder sheet is liquid phase sintered (including a half wave phase state) to form a sintered layer on the surface of the metal substrate. This is a characteristic feature.

(Effects of the Invention) According to the present invention, by adhering a laminate in which a low melting point powder sheet and a high melting point powder sheet are superimposed on the surface of a metal substrate, the pressure sensitive adhesive or adhesive of the powder sheet is burned out. Even if the temperature rises and a liquid phase is generated on the surface of the low-melting point powder sheet, the gas will be released through the high-melting point powder sheet and will reach the joint between the metal substrate and the laminate. Gas does not accumulate, it is possible to prevent defects such as swelling or dents in the sintered layer, and processing costs are also reduced, resulting in reductions in material costs and processing costs.

In addition, when sintering the laminate, after placing the laminate on the metal base, heat and hold at a temperature of 150 to 380°C for 5 minutes or more before liquid phase sintering, until the sintering temperature is reached. The laminate has good adhesion, and the sintered layer formed by the laminate and the metal base are bonded well to each other, so that a sintered layer of excellent quality can be obtained.

(Example) FIG. 1 is a sectional view showing a state in which a laminate is adhered to a metal base in one embodiment of the present invention.

A laminate 4 in which a low melting point powder sheet 2 and a high melting point powder sheet 3 for forming a sintered layer are laminated is adhered to the surface of an iron-based metal base 1.

The low melting point powder sheet 2 has a melting point of, for example, 950 to 115.
It is formed by kneading an adhesive made of acrylic resin with an alloy powder that has wear resistance at a low temperature of about 0°C. Also,
The high melting point powder sheet 3 is formed by kneading an adhesive made of acrylic resin with a metal powder having a melting point higher than that of the alloy powder of the low melting point powder sheet 2 (for example, 1050° C. or higher), and 7- Metal substrate 1 The high melting point powder sheet 3 is interposed between the low melting point powder sheet 2 and the low melting point powder sheet 2, and the two are bonded using self-adhesive pressure bonding or an adhesive.

In the state where the laminate 4 is adhered to the metal base 1,
The high melting point powder sheet 3 has a joint surface with the low melting point powder sheet 2 (
It has an upper surface) and an atmosphere open surface (outer peripheral surface), and is provided so that the gas generated from the low melting point powder sheet 2 is guided and released from the atmosphere open surface.

Thereafter, the laminate 4 is heated and held at a temperature of 150 to 380° C. for 5 minutes or more in a non-oxidizing atmosphere (vacuum or hydrogen gas atmosphere), and then further heated in a non-oxidizing atmosphere (7).
950-1150 under vacuum or hydrogen gas atmosphere)
The low melting point powder sheet 2 was sintered in a liquid phase at a temperature of .degree. C. while the high melting point powder sheet 3 was in a solid state to form a sintered layer having wear resistance on the surface of the metal substrate 1.

On the other hand, FIG. 2 is a sectional view showing a state in which a laminate is adhered to a metal base according to another embodiment of the present invention.

In this example, the laminate 5 to be adhered to the metal substrate 1 is made by adhering multiple layers of low melting point powder sheets 2 and high melting point powder sheets 3, similar to the previous example, alternately in the direction perpendicular to the bonding surface of the metal substrate 1. After the laminate 5 is adhered, the powder alloy sheet 2 is heated and sintered in the same manner as described above to form a wear-resistant sintered layer on the metal base 1.

In the state where the laminate 5 is adhered to the metal base 1,
The high melting point powder sheet 3 has a joint surface with the low melting point powder sheet 2 (
It has a surface (both side surfaces) and an atmosphere open surface (upper end surface), and is provided so that the gas generated from the low melting point powder sheet 2 is guided and released from the atmosphere open surface.

The laminate 5 shown in FIG. 2 is made by alternately stacking a large number of belt-shaped low-melting point powder sheets 2 and high-melting point powder sheets 3 having a wide area, and pressing them together with a pressure roll 6, as shown in FIG. After that, it is cut to a predetermined thickness. Note that the low-melting point powder sheet 2 and the high-melting point powder sheet 3 are bonded together using self-adhesive pressure bonding or an adhesive.

In each of the above embodiments, the metal base 1 has a laminate 4,
After adhesion in step 5, during heat treatment held at 150 to 380°C for 5 minutes or more (for example, 300°C x 60 minutes), the low melting point components of the acrylic resins of the low melting point powder sheet 2 and the high melting point powder sheet 3 are heated. The gas is released relatively freely, and part of it becomes tar-like due to the polycondensation reaction, ensuring adhesion between the metal substrate 1 and both powder sheets 2.3 at high temperatures.

Next, in the sintering process, when heated to about 1050°C, high boiling point component gas is generated, but at this point, the low melting point powder sheet 2 has started to produce a liquid phase from the surface (the surface open to the atmosphere), and on the other hand, Since the high melting point powder sheet 3 has a high melting point, pores are formed by burning off the organic components while the sheet is still in the same phase, so the generated gas passes through the high melting point powder sheet 3 and is released from the surface open to the atmosphere. When heated further,
Gas generation of the high-boiling point components is also finished, and the low-melting point powder sheet 2, the high-melting point powder sheet 3, and the metal base 1 are diffused into each other to complete the sintering bond.

The above-mentioned low melting point powder sheet contains 15 to 2.5% by weight of PO.

0165~4.5% by weight, MO2, 5~10.5mm
%.

85-97% by volume of wear-resistant eutectic alloy powder consisting of 01510% by weight, balance Fe, and powder particle size of 150 mesh or less
and 15 to 3% by volume of an acrylic resin adhesive dissolved in a solvent are kneaded, then rolled and cut into a predetermined shape.

Furthermore, to explain specific examples of low melting point powder sheets, Pl, 2% by weight, MO4, 9% by weight, Cr6
．． 97% by weight (91% by volume) of wear-resistant eutectic alloy powder with a particle size of 200 mesh or less, and acrylic resin adhesive. Toluene was added to 3% by weight (9% by volume) of the agent, wet kneaded, and rolled to a density of 4.60/Cl.
113 was formed into a sheet with a thickness of 1.5 mm, and this was cut into a size of 151111 x 18 mm to prepare a sample of a low melting point powder sheet.

In addition, specific examples of high melting point powder sheets include Cr
12.0% by weight, Si0.6% by weight, Mn002% by weight
, 96% by weight (88% by volume) of alloy powder having a composition of pO,002% by weight, balance Fe, and a particle size of 80 mesh or less (including 200 mesh or less by 5011-mold mouth%).
Toluene was added to and 4% by weight (12% by volume) of an acrylic resin adhesive, wet-kneaded, and rolled into a sheet with a density of 4.80/Cll13 and a thickness of 0.5ml1ll. was cut into a size of 15 m x 18 mIIl to prepare a sample of a high melting point powder sheet. This high melting point powder sheet has a relatively large adhesive content, so it has self-adhesive properties, and the number of pores formed by burning out the adhesive increases, resulting in increased gas flowability.

The above-mentioned low melting point powder sheet and high melting point powder sheet were pressure bonded with a roll to form a laminate, this laminate was adhered to the surface of a steel metal substrate, and the following heat treatment was performed.

Heat treatment (under H2 gas atmosphere) ■→■→■■ Temperature increase rate 10℃/min → 300℃×60 minutes■ Temperature increase rate 15℃/
Minutes → 1060℃×15 minutes ■ Heating rate 5℃/min → 10
After the above heat treatment at 90°C for 20 minutes, it was slowly cooled (cooling rate: 6°C/min) to obtain a wear-resistant sintered layer bonded to the surface of the metal substrate. Furthermore, no defects such as swelling or depressions were observed in this sintered layer.

Furthermore, during sintering, the liquid phase of the low melting point powder sheet penetrates about 1 mm into the pores of the high melting point powder sheet, so the pores of the high melting point powder sheet are completely blocked.

In addition, in the above heat treatment, at a temperature of 1060 ° C.
The reason for holding for 5 minutes is to equalize the heating temperature of the laminate housed in the sintering furnace, since the temperature rise is uneven in each part. It is not necessary if there is.

In addition to the composition of the metal powder shown in the examples, the high melting point powder sheet may be made of pure Fe powder or Fe powder containing a small amount of C. The thickness is preferably 1/3 or more of the total thickness of the laminate for effective degassing, specifically 0.511IIl1 or more, and in the case of Fig. 2, for example, The melting point powder sheet is 1
A low melting point powder sheet of 11Il is made to have a thickness of 3 mm, and the area ratio of the two is 1:3. In addition, in order to effectively degas, the proportion of pores generated by burnout of the adhesive is relevant, and the value is preferably in the range of 20 to 60%, and if it is less than 20%, degassing becomes difficult. 60%
If it exceeds this amount, the amount of metal powder to be sintered will be small and the sintering strength will be reduced.

Here, the laminate consisting of the low melting point powder sheet and the high melting point powder sheet will be explained in more detail. Normally, resin adhesives can adhere to the base material at temperatures of 200 to 300°C, but if the temperature rises further, the adhesive burns out and evaporates, losing its adhesive function and bonding to the base material. The adhesion with the product will be lost. Therefore, if the weight of the laminate, such as the sloped or curved surface of the base material or the downward facing surface, acts on the adhesive surface with the base material, it will no longer be able to support the weight of the laminate and it will peel off from the base material. Or there is a risk that it will fall off. In particular, in equipment where vibrations and shocks do not act on the workpiece, adhesive strength with the base material is not required so much, but in mesh belt-type or pusher-equipped continuous sintering furnaces, vacuum sintering furnaces, etc., vibrations and shocks during transportation are not required. Unavoidable. On the other hand, there is no problem between room temperature and 200℃, where the adhesive has strong adhesive strength, but at higher temperatures, the metal powder begins to sinter7.
If strong vibrations or shocks are applied until the temperature reaches around 00℃, the bonding force due to the carbonized adhesive will be weak.
This will cause the laminate to peel off.

Regarding the above point, as mentioned above, alloy powder (metal powder) 8
5-97% by volume and acrylic resin adhesive 15-3% by volume
After kneading and kneading, the rolled sheet is adhered to an iron base material using an acrylic resin with adhesive properties, and heated at 150-380°C, preferably 200-350°C in a non-oxidizing atmosphere.
If the temperature is heated at a temperature increase rate of 40°C/min or less to a processing temperature between 0°C and maintained at this temperature for 5 minutes or more, low boiling point components will volatilize from around 120°C, and the temperature will rise to around 200°C. A thermal decomposition polycondensation reaction occurs and a tar pitch-like substance is produced. Since this tar pitch-like substance has adhesive properties, it can provide adhesive strength that can withstand vibrations and impacts caused by transportation at temperatures of 300° C. or higher.

15- The above phenomenon will be explained along with the test results shown in FIG.

This test is MOIO, 5% by weight, Cr 2.5% by weight.

Ternary eutectic alloy powder with a chemical composition of 2.4% by weight of P, 3.6% by weight of C, and the balance of Fe, with a particle size of 150 mesh or less, 48.5% by weight, S LJ S 410 powder with a particle size of 150 mesh or less 48.5% by weight and 3% by weight (9% by volume) of acrylic resin were wet-kneaded with acetone and rolled to a density of 4.8o/cm3. Thickness 2ml1
The sheet was formed into a sheet and cut into 1 cm x i cm, and the sheet was adhered to the vertical surface of a steel base material using the same acrylic resin adhesive sheet (thickness: 10 μm) so as to form an adhesion surface of 10 m x 10 m. At this time, the weight of the powder alloy sheet is approximately 0.96], so the adhesive surface is 0.96Q10
A shearing force of m2 is acting, and if the adhesive strength is greater than this value, the sheet will not fall off.

In Figure 4, sample ■ is an untreated sample heated in a nitrogen gas atmosphere and subjected to high-temperature shear tests at various temperatures.The shear strength was approximately 50,000/cm2 at room temperature, but at 100℃. 3000 by softening the adhesive
o/am2 or less. Furthermore, thermal decomposition of the acrylic resin begins at about 20016-°C, and the strength decreases as the resin decomposes.At about 400°C, the strength decreases significantly due to rapid decomposition, and the sheet falls off. Here, it is considered that the sheet could not withstand the shear force due to the gravity of the sheet, so it can be inferred that the shear strength was approximately 1 q/Cll12 or less.

On the other hand, samples n, m, and rv were heated in advance in a hydrogen gas atmosphere at a heating rate of 10°C/min, and each was heated to 300°C.
The samples were heat treated for x60 minutes, 250℃ x 60 minutes, and 380℃ x 60 minutes, and then slowly cooled to room temperature.The samples were then heated again and high-temperature shear tests were conducted at each temperature. Due to the presence of unreacted resin, the strength gradually decreases. When the temperature exceeds 400° C., unreacted resin evaporates, carbonization of the tar pitch-like substance progresses with heating, and adhesive strength decreases. However, when the temperature exceeds 100°C, the strength increases as the solid phase sintering of the alloy powder progresses, and furthermore, when the temperature approaches 1000°C, a liquid phase crystallizes due to the eutectic component, and the liquid phase component is transferred to the base material. The shear surface strength increases significantly as it solidifies again by diffusing into the surface.

Therefore, when the temperature is raised continuously like sample ①, 38
There is a possibility that it will fall off at temperatures exceeding 0℃, but sample 11
．． Those that have been heat-treated in advance, such as I[1 and IV, are adhered without falling off.

Furthermore, in order to elucidate the above phenomenon, an experiment shown in FIG. 5 was conducted. This experiment was conducted using an acrylic resin adhesive [(meth)
Figure 3 shows weight loss when acrylic acid alkyl ester-acrylic acid copolymer] is heated in a nitrogen gas atmosphere. Note that the rate of temperature increase to each temperature described later is 15° C./min. Approximately 10% of the acrylic resin adhesive decomposes at 300°C, and when heated further, it rapidly decomposes at around 400°C, resulting in approximately 90% decomposition.

On the other hand, in a nitrogen gas atmosphere, the temperature was increased to 300°C along the heating characteristic a.
In sample A heated for 60 minutes, about 40% decomposed due to heating in a non-oxidizing atmosphere and the remaining about 6
0% undergoes a thermal decomposition polymerization reaction and turns into a tar pitch-like substance. This tar pitch-like substance causes 4
It is considered to have adhesive strength, that is, holding power, from 00 to 700°C.

In addition, in sample B, which was heated at 400°C for 60 minutes along the heating characteristics, about 90% was decomposed, and the formation of tar pitch-like substances that have adhesive strength at 400°C or higher is reduced. Sheets are falling off, etc. moreover,
The same thing can be said for Sample C heated at 500° C. for 60 minutes along heating characteristic C as well as Sample B (400° C. for 60 minutes). As mentioned above, rapid resin decomposition occurs at 400°C.
At high temperatures above 700°C, the contribution of the generated tar pitch-like substances becomes dominant, and solid phase sintering of the alloy powder begins at 700°C.
It is thought that it will continue into the vicinity.

In order to confirm the formation of the tar pitch-like substance mentioned above, elemental analysis was performed on acrylic resin adhesives held at 300°C for 60 minutes in a nitrogen gas atmosphere and then heated at 500°C and 700°C. The weight percent of the elements and the 1''/C atomic ratio are shown below. Sample 1 is 5
Sample 2 was heated to 70019°C.

CHH/C Sample 191.7% 5.9% 0.71 Sample 2 95.
2% 1.4% 0.18 Here, pitches are 1% of asphalt in terms of H/C atomic ratio.
．． It ranges from 0 or more to 0.5 to 0.6 for coal tar pitches.

Therefore, in the case of sample 1, H/C was 0.17, and it was confirmed that tar pitch-like substances remained. Sample 2
The H/C is 0.18, and as carbonization progresses, tar pitch-like substances decrease, but metal sintering begins around this temperature and transitions to a strong metal bond. be.

In addition, in the heat treatment of the laminate before sintering, the heating atmosphere is hydrogen gas in an inert gas such as nitrogen gas or argon gas to prevent oxidation of the alloy powder, metal powder, and acrylic resin adhesive. It is necessary to carry out the process in a non-oxidizing atmosphere such as a vacuum or in a reducing gas such as. Also, increase the temperature increase rate to 4
The temperature is set at 0°C/min or less because if the temperature increase rate exceeds 40°C/min, the low boiling point valve in the acrylic resin adhesive will rapidly volatilize.
Do not damage the laminate or cause bubbles to form on the adhesive surface and cause it to fall off.
This is to prevent this from happening.

Then, the heating temperature is set to 150 to 380°C, preferably 200°C.
The reason why the temperature is set at ~350°C is that the amount of undecomposed adhesive increases below 150°C, causing rapid decomposition when heated above 400°C, and the amount of tar pitch-like substances produced is small. On the other hand, if the temperature exceeds 380°C, the adhesive will rapidly decompose, and the amount of tar pitch-like substances that contribute to adhesion will be small, causing the laminate to fall off. This is because there is a possibility that Furthermore, the optimal holding time for 5 minutes or more differs depending on the heating temperature, but if it is less than 5 minutes, the amount of tar pitch-like substances produced will be small and the adhesion will be insufficient; Since heating is not economical, it is preferable to set each of the above conditions within such ranges in order to perform a good treatment.

In addition, it goes without saying that the alloy powder of the low melting point powder sheet in the laminate must have wear resistance when heated and sintered, but the adhesion of the acrylic resin adhesive depends on the temperature. Since there are limitations in terms of performance, it is preferable that the sintering temperature be as low as possible. This also applies to the high melting point powder sheets 1 to 1.

From this point of view, it is preferable to use a wear-resistant eutectic alloy powder, particularly a Fe-MC-based ternary eutectic alloy powder, as the wear-resistant alloy powder, and M includes Mo, B, and P. It is preferable to use one of these or a combination thereof. In particular, it is preferable to use P because, like C, it has strong diffusibility into the base material.

In addition, Or and V are secondary elements that improve the strength and wear resistance of the Fe-M-C ternary eutectic alloy.

W, Nb, Ni, and Ti are effective, and other elements such as 3i, Ni, and Mn are also useful for improving various performances, and are preferably added.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a state in which a laminate is adhered to a metal base in one embodiment of the present invention, and FIG. 2 is a sectional view showing a state in which a laminate is adhered to a metal base in another embodiment of the present invention. , Fig. 3 is a perspective view showing an example of forming the laminate in Fig. 2, Fig. 4 is a characteristic diagram showing the relationship between shear surface strength and temperature with respect to the heating temperature of the laminate before sintering, and Fig. 5 is an acrylic A characteristic diagram showing the weight loss when the resin adhesive is heat-treated in the range of 300 to 500°C and then heated in a nitrogen gas atmosphere. Figures 6A to 6D show the sintering process in order and the occurrence of defects. FIG. 7 is a graph showing the results of measuring the state of gas generation accompanying heating of the acrylic resin adhesive to the sintering temperature using Gas Chroma 1-Graph. 1...Metal base 2...Low melting point powder sheet 3...High melting point powder sheet 4.5...Laminated body L zLu'v5) 141 kon' I +←(tsu.)1
lid

Claims (1)

[Claims] (1) A method for forming a sintered layer bonded to the surface of a metal substrate, which comprises a low melting point powder sheet formed by kneading a wear-resistant, low melting point alloy powder with an adhesive made of acrylic resin. A high melting point powder sheet formed by kneading a high melting point metal powder with an adhesive made of acrylic resin is provided, and the high melting point powder sheet has a joint surface with the low melting point powder sheet and a surface open to the atmosphere. The high melting point powder sheet and the low melting point powder sheet are overlapped and adhered to form a laminate, the laminate is adhered to the surface of a metal substrate, and then the laminate is heated at 150 to 380°C in a non-oxidizing atmosphere. 1. A method for forming a sintered layer on a metal substrate surface, which comprises heating and holding at a temperature of 5 minutes or more, and then performing liquid phase sintering of a low melting point powder sheet with at least the high melting point powder sheet in a solid phase state.