JP2020002427A - Wear-resistant composite material and method of producing the same - Google Patents

Abstract

To provide a wear-resistant composite material that is excellent in wear/corrosion resistance and can be made in broad sizes applicable also to hard armoring of a base material or into a near net of a desired shape, a member using the same, and a method of producing the same.SOLUTION: A wear-resistant composite material is made to be a near net by filling a self-fluxing alloy singly or a mixed powder 10 in which a super abrasive grain of a diamond or cBN grain is dispersed using a self-fluxing alloy as a base, in a gap between a ferrous base material 5 and a mold 9, temporarily sintering the mixed powder 10 at a temperature in a vacuum or non-oxidation atmosphere, diffusion-bonding a temporarily sintered body firmly to a surface of the ferrous base material, and removing the mold 9 and then performing main sintering in a non-oxidation atmosphere.SELECTED DRAWING: Figure 2A

Description

  The present invention relates to a composite material for a wear-resistant and corrosion-resistant member used for a drill bit and the like, and a method for producing the same.

  A drill bit used for energy development of oil, natural gas, geothermal, and the like requires not only the ability to excavate rock but also the property of maintaining the excavated hole diameter. FIG. 1A is an appearance photograph of a typical drill bit (tricone bit), and FIG. 1B is a partially enlarged photograph thereof. The bit gauge portion 2 of the tricone bit for excavation receives the excavation load 7 and the anti-wall pressure 8 from the rock, and wears due to friction with the rock, thereby reducing the diameter of the excavation hole. This causes the bit to be used next to be damaged in a short time, resulting in a decrease in drilling efficiency. Also, the anti-wall pressure 8 acts in a direction in which the bit cutter comes off, so that the bearing 3 and the seal 4 are damaged. As a result, if the bit needs to be replaced, the cost is enormous, which leads to an increase in drilling cost. Therefore, countermeasures against bit wear are the most important issues.

  In order to improve the wear resistance of the bit, carbide chips are usually embedded or welded with carbide (including molten tungsten) particles. However, this is not sufficient, and ultra-high pressure diamond firing is not sufficient. In some cases, union is used. The inventors of the present application have developed and commercialized a diamond composite material (Patent Document 1). This is a composite material having excellent wear resistance in which diamond grains are dispersed in a cemented carbide. However, even if the wear resistance of the composite material tip is excellent, when the base material (steel material) 5 in which the chip is embedded wears, the chip falls off like alveolar pyorrhea, so that the wear resistance of the base material also increases. It becomes important.

  In order to improve the abrasion resistance of the base material, the surface of the steel material is hardened, and usually, hardening is performed to a thickness of about 1 to 3 mm by a thermal spraying or welding technique. For example, in Patent Document 2, by spraying a WC cermet excellent in abrasion resistance by a warm spray method, a spray roll having a porosity of 1.5% or less, a particle diameter of 5 μm or less, and an HV of 1050 to 1150 is obtained. It is disclosed. However, although it contains 10 to 40% of metal carbide (WC) but contains pores, it is not suitable for abrasion-resistant applications with heavy loads and impact. Patent Literature 3 discloses a composite material of diamond and resin, but is not metal-based and cannot be used for abrasion resistance application under heavy load and impact. Also, as described in Patent Document 1, there is a method in which diamond particles are dispersed in a cemented carbide and pressure-sintered. However, a super-abrasive tip by an ultra-high pressure method is extremely expensive, and the shape is restricted. Yes, it is not suitable for this application because it cannot produce large-sized objects. There is also an example of applying diamond abrasive grains by plating (electrodeposited diamond coating). However, since the bonding strength is weak and porous, it is mainly used for grinding stones, and it has wear resistance with heavy load and impact. Not suitable for use. In addition, many studies have been conducted to apply a high-hardness thin film coating of about several μm to the surface. For example, Patent Document 4 discloses a method of forming a diamond film, but the obtained film thickness is small. It is not suitable for wear-resistant hard wearing applications with heavy load impact.

Japanese Patent No. 5076044 (US Pat. No. 7,637,981) Japanese Patent No. 5013364 Japanese Patent No. 3490978 Japanese Patent No. 4358509 WO 2017/130283

  An object of the present invention is a composite material which is excellent in abrasion resistance and corrosion resistance, and which can be formed into a near net with a wide size applicable to hard work of a base material, or an arbitrary shape, and a member using the composite material. It is to provide a manufacturing method.

  Normally, hard coating with a thickness of about 1 to 3 mm is performed by spraying and welding techniques, but if super abrasive grains can be dispersed in this, a wear-resistant material that can be used as a base material of bits is realized It is possible to do. However, as far as the inventors know, there is no case where super abrasive grains are dispersed by thermal spraying or welding. The reason why it was not possible to use abrasive grains for thermal spraying and hard coating is that superabrasive grains are transformed into carbon by heat during construction (spraying, welding) or the specific gravity of superabrasive grains rises to the surface lightly Therefore, it is considered that they do not become semi-molten and do not adhere to the construction object (do not wet). For this reason, in the prior art, a metal carbide mainly composed of WC was dispersed in a self-fluxing alloy, and it was possible to densify the WC by melting it to about 40%. In the case of addition, it was necessary to carry out thermal spraying treatment such as high-speed plasma. However, the thermal spraying treatment could not be densified because of containing fine bubbles, and could not obtain impact resistance.

  In view of this, the present inventors have developed a self-fluxing alloy containing Co or Ni in part or all of WC in a diamond composite material which is a sintered body of a cemented carbide (WC-Co) and diamond particles described in Patent Document 1. Research was conducted with the aim of dispersing diamond and / or cBN (cubic boron nitride) in a self-fluxing alloy. The self-fluxing alloy has high hardness, low melting point and wide semi-melting range, and is suitable for this research purpose.

Conditions necessary for dispersing diamond in a metal material such as a self-fluxing alloy include the following conditions.
(1) The diamond does not deteriorate due to heat treatment in a vacuum or atmosphere. That is, the temperature must be short and 1100 ° C. or less. When cBN is used instead of diamond, the temperature must be shorter than 1200 ° C.
(2) The mixed powder of diamond and hard metal is filled in a mold without segregation.
(3) The diamond does not move (lift) in the mixed powder.
(4) The mixed powder adheres firmly to the surface of the work under heat treatment (sintering temperature) conditions. If the adhesion is insufficient, the mixture shrinks due to sintering, and the end face is turned up or cracks occur.
(5) Complete sintering (no air bubbles). In this case, contraction occurs only in the thickness direction.

  The hard work according to the present invention is manufactured using a female carbon mold 9 slightly larger than the shape of the target work and the metal base material 5 slightly smaller than the shape of the target work (FIG. 2A). The gap between the carbon mold and the metal base material is sufficiently filled with a mixed powder 10 of diamond or cBN superabrasives and a self-fluxing alloy at a temperature near the temperature at which the self-fluxing alloy starts sintering shrinkage. Hold enough. In addition to diamond or cBN, metal carbide or the like may be added to the mixed powder as superabrasives. Even better results can be obtained by applying a small amount of a low melting point material having a melting point of about 900 ° C. such as Ni low on the surface of the base material. In addition, the self-fluxing alloy has a wide range of semi-solid state from solid phase to liquid phase and has an appropriate viscosity, so that it is suitable for such use. The filled mixed powder is hardened and hardened (temporarily sintered), and at the same time, is strongly held by diffusion bonding of steel with iron. Next, the carbon mold 9 is removed, and the pre-sintered body and the base steel are sintered at an appropriate temperature (1100 ° C. or less; 1200 ° C. or less when the superabrasive is cBN). If heating is performed to the sintering temperature at a time without performing preliminary sintering, the mold 9 and the filler 10 adhere to each other and cannot be taken out, resulting in breakage. Since the mold 9 cannot be recycled, a temporary sintering step is required.

  In order to satisfy the above-described dispersion condition, it is necessary to provide a gap (space) of 0.3 mm or more between the carbon mold 9 and the base metal 5 and fill the mixed powder 10. If the gap is smaller than this, it becomes difficult to fill the powder. It is important to keep the surface of the base metal 5 clean in order to adhere firmly. As the self-fluxing alloy, it is preferable to use Colmonoy (registered trademark) or 1355 manufactured by Höganäs. The best material for the mold is carbon, which has good thermal conductivity. Further, the carbon mold 9 can be easily removed. FIG. 2B shows a photograph of the appearance (left) and a photograph of a cross section (right) of a test piece having a hard coating formed on the left end of the base metal produced as described above.

  Since the base metal and the pre-sintered body are strongly held by diffusion bonding, sintering shrinkage is restricted in the thickness direction. Therefore, although the thickness shrinkage ratio is larger than that of normal sintering, since the sintering is performed in proportion to the thickness at the time of filling, the thickness of the hard material is the shrinkage ratio × the thickness of the filling. Since the filling thickness is uniform, the dimensional variation after sintering is within plus or minus 0.1 mm or less, making it possible to manufacture a near net.

Table 1 shows a comparison between conventional thermal spraying and the present invention.

  By the method according to the present invention, it has become possible to apply hardening of an arbitrary shape with a composite material of superabrasive grains (diamond or cBN) -self-fluxing alloy on the surface of the base metal. Various composite materials such as metal carbides can be added to the composite material with high precision. For this reason, by optimizing the adjustment of the amount and the particle size of the superabrasive grains, an excellent wear-resistant member can be provided in various applications. Also, since almost 100% of the input raw material powder is hardened during construction, there is no adhesion yield loss such as thermal spraying, and the material yield is particularly excellent.

  Compared with the above-described diamond composite material (Patent Document 1), the hard dress or construction according to the present invention has an effect that the ground becomes a hard metal from a hard metal and the toughness and impact resistance are enhanced. The hard material containing diamond or cBN super-abrasive particles according to the present invention is an epoch-making material and can cover a wide area, so that the wear resistance can be enhanced as compared with the conventional hard material. When the hardening according to the present invention is applied to an excavation bit, a wide convex file surface containing superabrasive grains and WC particles is formed, so that the wellhead grinding power can be strengthened as compared with the related art. Thereby, the surface pressure of the anti-wall is reduced, and the protection of the bearing and the strengthening of the seal can be achieved.

  Further, according to the present invention, a construction object having an arbitrary shape and size can be manufactured depending on a mold. In addition, since the variation in the dimensions after manufacturing is within plus or minus 0.1 mm or less, it is possible to harden the near net. As a result, it is possible to significantly reduce the processing cost for manufacturing the construction. Due to this advantage, in applications that do not require much wear resistance, it can be used in various applications as a hard dress using metal carbide as super abrasive grains without mixing diamond or cBN into powder. is there.

A photo of the entire appearance of the drill bit (left) and an enlarged photo of the exterior (right). It is a typical sectional view of an excavation bit. FIG. 3 is a schematic sectional view showing a method for producing a construction according to the present invention. It is an outline photograph (left) and a cross-sectional photograph (right) of a test construction manufactured according to the present invention. 1 is a schematic cross-sectional view (left) of a shaft-shaped construction produced according to the present invention, a photograph of the appearance after sintering (middle), and a photograph of the appearance after centerless processing (right). FIG. 2 is a schematic cross-sectional view (left) of a sleeve-cylindrical shaped object manufactured according to the present invention, and an appearance photograph after sintering (right). FIG. 2 is a schematic cross-sectional view (left) of a drum-shaped roll-shaped construction manufactured according to the present invention, and appearance photographs (middle) and (right) after sintering. It is a drill bit (middle) produced by the present invention, a base material before production (left), and a cross-sectional photograph (right) of a construction. It is a structure | tissue photograph of the cross section of the prototype which applied the 1-mm-thick layer of the composite material containing the diamond particle of 60-80 micrometers diameter. It is a structure | tissue photograph of the cross section of the prototype which applied the 1-mm-thick layer of the composite material containing the cBN particle | grains of 30-40 micrometers diameter.

(Example 1)
As a preliminary prototype of the construction according to the method of the present invention, a hard material containing diamond grains was formed on the surface of a base material of a rotating body having various shapes. 3A, 3B, and 3C are schematic cross-sectional views (left) of a workpiece on a base material having a shaft-type shape, a sleeve-cylindrical shape, and a drum-shaped roll shape, respectively, and appearance photographs after sintering. Right). In the case of the shaft type, it was confirmed that the centerless processing could be performed without any problem after the formation of the hard material, and it was found that a uniform hard material was firmly formed on the surface of the base material in any shape.

(Example 2)
A prototype of a bit cutter was prototyped by the method of the present invention. As shown in FIG. 4, a concave slit having a depth of 2 mm was radially formed in a gauge portion of a base material (iron) of a bit cutter, and a carbon mold was placed thereon. The space between the gaps was filled with a mixture of 40% by weight of composite particles (Patent Document 5) in which the cemented carbide particles were wrapped with diamond having an average diameter of 30 μm, and a mixture consisting of the self-fluxing alloy Heganes 1355. And the whole was hold | maintained at 950 degreeC for 60 minutes in the heating furnace, and calcined. Thereafter, the mold was removed, and sintering was performed at 1030 ° C. for 30 minutes to obtain a member on which a hard layer was formed (FIG. 4 (middle)). As shown in the cross-sectional photograph of FIG. 4 (right), it can be seen that a dense hard layer (upper end) is formed by being fixed to the base material.

(Example 3)
FIG. 5 is an enlarged photograph of a cross-sectional structure of a hardened surface portion of a prototype in which a 1 mm-thick hard layer of a composite material containing diamond grains having a diameter of 60 to 80 μm is applied to the outer periphery of a steel round bar having a diameter of 25 mm. . The diamond particles are contained in the composite material at 10% by volume. It can be seen that the diamond grains are relatively uniformly dispersed.

(Example 4)
FIG. 6 shows a surface hardened portion of a prototype in which a 1 mm-thick hard layer of a composite material containing cBN particles having a diameter of 30 to 40 μm instead of diamond particles was applied to the outer periphery of a similar φ25 mm iron round bar. It is an enlarged photograph of a cross section structure. The cBN particles are contained at 10% by volume in the composite material. Also in this case, it can be seen that the cBN particles are relatively uniformly dispersed.

  Although the above description has been made with reference to the embodiments, the present invention is not limited thereto, and it is apparent to those skilled in the art that various changes and modifications can be made within the spirit of the present invention and the scope of the appended claims. It is.

  The wear-resistant and corrosion-resistant composite material according to the present invention can be used as a wear-resistant member of a drill bit and other drill tools used for energy development of petroleum, natural gas, geothermal, and the like. Further, it can be formed to cover the surface of the base material widely, and can also be applied to hard work of the base material. Furthermore, since the member can be manufactured in a near net, a hard construction having an arbitrary shape more complicated than before, such as various valves of an internal combustion engine, a rocker arm, or a ball of a ball valve for a valve device, a gate valve, etc. Application is possible.

1 bit,
2 Gauge part 3 Bearing 4 Seal part 5 Base material 7 Excavation load 8 Surface pressure from side wall 9 Type 10 Mixed powder

Claims (13)

  A wear-resistant composite material in which a layer of any shape of a self-fluxing alloy alone powder or a self-fluxing alloy-based mixed powder is sintered and bonded to a near net on the surface of a ferrous metal base material.   The wear-resistant composite material according to claim 1, wherein super-abrasive grains of diamond grains and / or cBN grains are further mixed with the mixed powder.   The wear-resistant composite material according to claim 2, wherein the superabrasive grains are contained in the composite material in an amount of 1 to 30% by volume.   The wear-resistant composite material according to any one of claims 1 to 3, wherein a thickness of the powder layer is 0.2 mm or more.   A member or tool for excavation, a member for a valve device, or a member for an internal combustion engine using the wear-resistant composite material according to any one of claims 1 to 4. A step of filling a gap between a base material of an iron-based metal and a mold arranged so as to cover the base material with a powder of a self-fluxing alloy alone or a mixed powder based on a self-fluxing alloy,
A step of temporarily sintering the powder at a temperature lower than a temperature at which sintering shrinkage starts in a vacuum or a non-oxidizing atmosphere for a predetermined time, and strongly diffusing a temporarily sintered body to the surface of the base material; When,
Performing a main sintering in a non-oxidizing atmosphere after removing the mold.   7. The method of claim 6, further comprising mixing superabrasives with the powder.   The method according to claim 6, wherein the superabrasive grains are diamond grains, and the sintering temperature is 1100 ° C. or less.   The method according to claim 6, wherein the superabrasive grains are cBN grains, and the sintering temperature is 1200 ° C. or less.   The method according to any one of claims 7 to 9, wherein the superabrasive is contained in the composite material in an amount of 1 to 30% by volume.   The method according to any one of claims 6 to 10, wherein the mold is carbon.   The method according to any one of claims 6 to 11, wherein a gap between the base material and the mold is 0.3 mm or more.   The method according to any one of claims 6 to 12, wherein the size of the shape of the wear-resistant composite material after the main sintering has a variation of ± 0.1 mm or less.