Production method of high-toughness microcrystal hard alloys

A technology of cemented carbide and manufacturing method, applied in the field of cemented carbide, can solve the problems of low mixing efficiency, elimination difficulty, uneven mixing, etc., and achieve the effects of reducing the surface roughness of the workpiece, improving the durability, and improving the cutting force of the tool

Active Publication Date: 2014-09-10
HEYUAN ZHENGXIN HARDMETAL CARBIDE
7 Cites 10 Cited by

AI-Extracted Technical Summary

Problems solved by technology

Traditional cemented carbide manufacturing methods have difficulties in eliminating defects in powder and sinte...
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Method used

In the present invention, in batching process, raw material selection HCP value is (39 ~ 41) KA/m superfine grain WC powder, adds the superfine Co powder of 8 ~ 12%, and adding weight percent is 0.2% ~0.6% VC, 0.1%~0.5% by weight of B4C, 0.1%~0.5% by weight of NbC, 0.3%~2.0% by weight of TaC, 0.1%~0.5% by weight of Mo2C, And through the analysis and inspection, the carbon balance value when calculating the ingredients is (+0.15~+0.20)%, and the average grain size of WC in the cemented carbide reaches (0.25~0.35) μm. Adding 0.1%~0.5% of B4C by weight can improve the wear resistance and bending strength of cemented carbide.
The ball milling operation described in the present invention adopts high-energy planetary ball mill ball mill, ball mill medium and each raw material powder are mixed in proportion, raw material powder is fully broken, more uniform than traditional process mixing, mixing efficiency is higher, and to a certain extent increase the sintering activity. The granulation process (including sieving and drying and waxing process) uses inert gas (N2, Ar) to atomize the alloy powder prepared, wherein the sieving and drying process uses inert gas (N2, Ar) to protect the alloy powder, so that The alloy powder is separated from other gases to prevent the alloy powder from producing gases such as CO or CO2 that are not conducive to the mechanical properties of the alloy. The pressing process is an automatic pressing process, which uses automatic pressing to obtain a green body with a uniform distribution of green body density, and avoids secondary pollution that may be caused during the pressing process, and uses inert gas (N2, Ar) to protect the pressed product , to separate the pressed product from other gases to prevent the compressed product from producing CO or CO2 and other gases that are not conducive to the mechanical properties of the alloy. The sintering process described is a low-pressure sintering process (including dewaxing pre-sintering process), which adopts dewaxing pre-sintering and low-pressure low-sintering integrated furnace sintering. It is a relatively advanced process for densification of hard materials at present. 1. In the state with a large amount of liquid phase, the sintered material is completely densified with the help of a certain gas pressure, and the relative density is guaranteed to reach more than 99%. The traditional low-pressure sintering process is to dewax and pre-burn the pressed product in a vacuum sintering furnace, and then sinter it in a low-pressure sintering furnace. The sintering and low-pressure sintering integrated furnace sintering avoids this situation. Table 2 provides a comparison of the properties of the materials before and after low-pressure sintering treatment. It can be seen from Table 2 that after low-pressure sintering treatment, the porosity of the alloy decreases, the hardness increases slightly, and the bending strength increases significantly. Therefore, low-pressure sintering can significantly improve the overall performance of the alloy.
The working procedure process that the present invention manufactures micr...
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
View more

Abstract

The invention discloses a production method of high-toughness microcrystal hard alloys. The production method comprises the procedures of burdening, ball milling, palletizing (including sieving drying and wax mixing), pressing and low-pressure sintering (including wax removal preburning), wherein the process of the low-pressure sintering procedure is charging-vacuumizing-wax removal preburning when heating to the temperature of 300-500 DEG C-heat preservation when heating to the temperature of 1100-1300 DEG C-heating to a liquid-phase sintering temperature-Ar charging and pressurization-heat preservation and pressurization-depressurization and cooling-discharging; when ingredients are calculated, the carbon balance value is (+0.15-+0.20)% through analysis and inspection; and the average grain size of WC in the hard alloys reaches (0.25-0.35) microns. The method, provided by the invention, can improve the toughness and wear resistance of the prepared hard alloys, is suitable for producing nonferrous metal cutting blades, prominently enhances the durability of such materials as cast iron, carbon steel and alloy steel, reduces the workpiece surface roughness, and improves the cutter cutting force.

Technology Topic

Cemented carbideWax removal +11

Image

  • Production method of high-toughness microcrystal hard alloys

Examples

  • Experimental program(1)

Example Embodiment

[0012] The specific implementation of the present invention will be further described below:
[0013] The process of manufacturing microcrystalline cemented carbide in the present invention is divided into: batching → ball milling → granulation (including sieving drying and wax mixing process) → pressing → low pressure sintering (including dewaxing and pre-sintering process). The vacuum sintering method is different. The pressed product adopts the low-pressure sintering process, which is sintered in an integrated furnace for dewaxing and low pressure sintering. The specific process is: charging→vacuum→heating to 300~500℃ for dewaxing and prefiring → Heat up to 1200°C for heat preservation → heat up to the liquid phase sintering temperature → pressurize with Ar gas → heat preservation and pressurize → pressure-reducing cooling → unloading. At the same time, in the batching process of the present invention, the HCP value of the raw material is (39~41) KA/ m superfine grained WC powder, add 8~12% superfine Co powder, and add 0.2%~0.6% by weight of VC and 0.1%~0.5% by weight of B 4 C. The weight percentage is 0.1%~0.5% NbC, the weight percentage is 0.3%~2.0% TaC, the weight percentage is 0.1%~0.5% Mo2C, and the carbon balance value is (+0.15 ~+0.20)%, the average grain size of WC in the cemented carbide reaches (0.25~0.35)μm. The ball milling process adopts high-energy planetary ball mill ball milling to mix the ball milling medium and each raw material powder in proportion, so that the raw material powder is fully broken and mixed more uniformly, and the sintering activity is increased to a certain extent. In the granulation process (including the sieving drying and wax mixing process), the alloy powder prepared by atomization of inert gas (N2, Ar) is adopted, and the inert gas (N2, Ar) is used to protect the alloy powder in the sieving drying process. The pressing process is an automatic pressing process, which uses automatic pressing to obtain a green body with a uniformly distributed green density, and avoids secondary pollution that may be caused during the pressing process, and uses inert gas (N2, Ar) to protect the pressed product . The described sintering process adopts low pressure sintering process (including dewaxing pre-firing process), adopting dewaxing pre-firing and sintering integrated furnace sintering. It is a relatively advanced technology for densification of hard materials at present. It can work at higher sintering temperature and liquid temperature. In the state of more phasor, the sintered material can be completely compacted by a certain gas pressure to ensure that the relative density reaches more than 99%.
[0014] In the batching process of the present invention, the raw material is ultra-fine grained WC powder with HCP value (39~41) KA/m, 8~12% ultrafine Co powder is added, and the weight percentage is 0.2%~0.6% VC, weight percentage of 0.1%~0.5% B 4 C. The weight percentage is 0.1%~0.5% NbC, the weight percentage is 0.3%~2.0% TaC, the weight percentage is 0.1%~0.5% Mo2C, and the carbon balance value is (+0.15 ~+0.20)%, the average grain size of WC in the cemented carbide reaches (0.25~0.35)μm. Add 0.1%~0.5% by weight of B 4 C can improve the wear resistance and bending strength of cemented carbide.
[0015] Table 1 provides 0.3% by weight of B 4 C. Comparison of the performance of front and back materials. It can be seen from Table 1 that 0.3% by weight of B is added 4 C, the hardness increase is not obvious, and the bending strength is obviously improved. Because boron carbide is a solid harder than tungsten carbide, it has a high melting point. Under the condition of 1000~1100℃, VC transition metal and boron carbide powder react strongly to form metal boride, which can increase the hardness and toughness of the alloy. Therefore, the formula component adds B 4 C can improve the overall performance of cemented carbide.
[0016]
[0017] The ball milling process described in the present invention adopts high-energy planetary ball mill ball milling to mix the ball milling medium and each raw material powder in proportion, so that the raw material powder is fully crushed, and the mixing is more uniform than the traditional process, the mixing efficiency is higher, and the sintering is increased to a certain extent. active. In the granulation process (including the sieving drying and wax mixing process), the alloy powder prepared by inert gas (N2, Ar) atomization is used, and the inert gas (N2, Ar) is used to protect the alloy powder in the sieving drying process to make The alloy powder is separated from other gases to prevent the alloy powder from producing CO or CO 2 Such gases are not conducive to the mechanical properties of the alloy. The pressing process is an automatic pressing process, which uses automatic pressing to obtain a green body with a uniformly distributed green density, and avoids secondary pollution that may be caused during the pressing process, and uses inert gas (N2, Ar) to protect the pressed product , To separate the pressed product from other gases to prevent the pressed product from producing CO or CO 2 Such gases are not conducive to the mechanical properties of the alloy. The described sintering process is a low-pressure sintering process (including dewaxing pre-sintering process). It is sintered in an integrated furnace of dewaxing pre-sintering and low-pressure low sintering. It is currently a relatively advanced technology for densification of hard materials. It can be used at higher sintering temperatures. , When the liquid phase is large, the sintered material can be completely compacted by a certain gas pressure to ensure that the relative density is above 99%. The traditional low-pressure sintering process is to dewax and pre-fire the pressed product in a vacuum sintering furnace, and then sinter it in a low-pressure sintering furnace. During the charging process, the pressed product is likely to produce CO or CO. 2 The gas is not conducive to the mechanical properties of the alloy, and the integrated furnace sintering of dewaxing, pre-sintering and low-pressure sintering avoids this situation. Table 2 provides a comparison of the properties of materials before and after low-pressure sintering. It can be seen from Table 2 that after the low-pressure sintering treatment, the porosity of the alloy is reduced, the hardness is slightly increased, and the bending strength is significantly improved. Therefore, low pressure sintering can significantly improve the overall performance of the alloy.
[0018] The low pressure of low pressure sintering in the present invention is relative to the pressure of hot isostatic pressing. Both are sintered under isostatic pressure, the pressure of the former is less than 10 MPa, and the pressure of the latter is as high as 100 MPa. Low pressure sintering is formed on the basis of vacuum sintering and hot isostatic pressing. Lower pressure at sintering temperature can eliminate pores in the alloy and avoid the defects of "cobalt pool" in the alloy due to high pressure. Low pressure sintering enables the alloy to obtain better comprehensive properties.
[0019] The advantage of using low pressure sintering in the present invention is that it can significantly reduce the microscopic pores in the alloy, and most of the pores in the sintered body have been eliminated in the vacuum sintering stage. The pressing stage is mainly to eliminate microscopic pores. Low porosity is an important sign of high-quality cemented carbide, and the porosity in the alloy should be minimized during production. The densification of cemented carbide is closely related to capillary force, wettability of liquid to solid phase and surface tension of liquid. As the temperature rises during the sintering process, when a liquid phase appears, due to the capillary pressure, the liquid phase moves to the surface of the WC. Because the liquid has good wettability relative to the WC phase, the liquid phase adheres to the WC surface well. Due to the surface tension of the liquid phase, the WC wrapped by the liquid phase is driven to move, and a strong contraction occurs. Under the action of pressure, the WC wrapped in the liquid phase moves, and during the shrinking process, the gas present in it is further discharged, and the degree of densification increases. However, as the shrinkage increases, pressure is generated in the closed pores. When the surface tension is equal to or less than the pressure in the pores, the closed pores are preserved in the alloy and form microscopic pores. Before low-pressure sintering, the WC particles are irregular polygons with sharp corners. There are defects such as holes in the structure, and they are concentrated in the dense areas of WC particles. After low-pressure sintering, the holes in the structure are significantly reduced or refined, which makes the alloy The key factors in the improvement of hardness and bending strength. Although both vacuum sintering and low-pressure sintering have a densification effect, the densification mechanism is different. In the vacuum sintering process, the reduction and spheroidization of pores are the driving force for the reduction and disappearance of pores; while in the low-pressure sintering process In addition to the continued action of this mechanism, the high-pressure environment also exerts an external force on the alloy, resulting in obvious viscoplastic flow, making it easier for atoms to move toward the pores and moving faster. In addition, under the simultaneous action of pressure and temperature, WC dissolves and precipitates in the alloy liquid phase, which makes the sharp corners of individual larger WC particles dull, the boundary becomes smooth, and the shape tends to be rounded. In cemented carbide, the sharp corners of the hard phase will cause stress concentration and have a cutting effect on the matrix. The rounding of the hard phase improves the mechanical properties of the alloy.
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to view more

PUM

no PUM

Description & Claims & Application Information

We can also present the details of the Description, Claims and Application information to help users get a comprehensive understanding of the technical details of the patent, such as background art, summary of invention, brief description of drawings, description of embodiments, and other original content. On the other hand, users can also determine the specific scope of protection of the technology through the list of claims; as well as understand the changes in the life cycle of the technology with the presentation of the patent timeline. Login to view more.
the structure of the environmentally friendly knitted fabric provided by the present invention; figure 2 Flow chart of the yarn wrapping machine for environmentally friendly knitted fabrics and storage devices; image 3 Is the parameter map of the yarn covering machine
Login to view more

Similar technology patents

Elastic hose

InactiveCN104672683AImprove wear resistance and toughnessExtended service lifeFlexible pipesBenzotriazoleTriethanolamine
Owner:QINGDAO JIASHANG CREATIVE CULTURE

Laser composite manufacturing hot galvanizing air knife lip and manufacturing method thereof

InactiveCN107400841AImprove wear resistance and toughnessMechanical properties and dimensional accuracy remain stableHot-dipping/immersion processesCorrosionEconomic return
Owner:谷云蕾

Method for producing melamine composite floor

PendingCN112848584AImprove wear resistance and toughnessEnhanced abrasion and scratch resistanceSynthetic resin layered productsLaminationPolymer chemistryHot-melt adhesive
Owner:ZHEJIANG KINGDOM NEW MATERIAL GRP CO LTD

Cast iron heat treatment technology for conveyor fitting

InactiveCN104789746AAvoid cracking and deformationImprove wear resistance and toughnessCast ironTreatment costs
Owner:ANHUI CHANGCHENG TRANSPORTATION MACHINERY MFG

Preparation method of chromium-doped hard alloy

ActiveCN109136602AImprove wear resistance and toughnessFast responseCemented carbideCorrosion
Owner:湖北绿钨资源循环有限公司

Classification and recommendation of technical efficacy words

  • Improve wear resistance and toughness
  • Improve durability

Casting technique for casting wear-resisting piece of motorcycle

InactiveCN106734895AImprove wear resistance and toughnessReduce porosityFoundry mouldsProcess efficiency improvementScrapPre treatment
Owner:重庆市合川区银窝铸造厂

Composite metal plate material of vehicle part and preparation method thereof

InactiveCN106756395AImprove wear resistance and toughnessHigh strengthHardnessCombustion
Owner:CHONGQING SHUAIBANG MACHINERY CO LTD

Environment-friendly plastic slurry for sports ground and preparation method of environment-friendly plastic slurry

InactiveCN108504080AIncreased elasticity and comfortImprove wear resistance and toughnessPrepolymerPlasticizer
Owner:SHAANXI SCI TECH UNIV

Metal ceramic anilox roller and manufacturing method thereof

InactiveCN109536869AImprove wear resistance and toughnessExtended service lifeInking apparatusMolten spray coatingOxy-fuelOxide ceramic
Owner:GUANGDONG INST OF NEW MATERIALS

Implantable collagen compositions

InactiveUS20060100138A1Improve durabilityImproved ease of handlingConnective tissue peptidesSurgical adhesivesTissue augmentation
Owner:FIBROGEN INC
Who we serve
  • R&D Engineer
  • R&D Manager
  • IP Professional
Why Eureka
  • Industry Leading Data Capabilities
  • Powerful AI technology
  • Patent DNA Extraction
Social media
Try Eureka
PatSnap group products