CBN composite material capable of processing nodular cast iron

Abstract

The invention discloses a CBN (Cubic Boron Nitride) composite material capable of processing nodular cast iron, which relates to the technical field of CBN composite materials and comprises the following components in percentage by mass: 25-30% of TiC, 5.0-12% of Al, 2.0-8.0% of Ti, 2.0-4.0% of Y2O3, 4.0-6.0% of Co, 1.8-2.2% of W, 2.0-8.0% of TaC, particles of which the particle sizes of the binding agents are 1-4 microns, and the balance of CBN particles of which the particle sizes are 1-2 microns. According to the CBN composite material capable of being used for machining the nodular cast iron, the hardness, the cutting length and the cutting speed of the CBN composite material prepared by using the components and the production steps are all improved, and the added Y2O3 can be adsorbed on the surfaces of CBN particles microcosmically, so that the growth of the CBN particles is inhibited, and the CBN particles can be pinned at the grain boundary to hinder the migration of the grain boundary; and the composite material can still maintain a fine grain structure at high temperature and maintain good high-temperature performance, so that the high-temperature hardness and strength of the composite material are improved.

Description

Technical Field

[0001] The invention relates to the technical field of CBN composite materials, and more particularly to a CBN composite material for machining ductile iron. Background Art

[0002] Ductile iron can effectively improve the mechanical properties of cast iron, especially the plasticity and toughness, thus obtaining higher strength than carbon steel and being able to withstand larger rolling loads. It is widely used in casting some automotive parts with complex stresses and high requirements for strength, toughness and wear resistance. Its application scope is gradually expanding to new energy parts such as wind power and photovoltaics.

[0003] However, ductile iron has poor cutting performance and is a difficult-to-process material, which results in a low lifespan of the composite material of CBN tools used to process ductile iron and poor wear resistance. The reasons are as follows:

[0004] 1. There are crystal defects such as dislocations inside the CBN crystal. Under the action of cutting force, dislocations will slip and proliferate. When dislocations move to the surface of CBN particles or grain boundaries, dislocations will cause disordered arrangement of surface atoms and form microcracks. These cracks continue to expand under the action of continuous cutting force, eventually leading to the breakage and shedding of CBN particles, causing tool wear.

[0005] 2. The BN bonds in CBN crystals have strong directionality. When impacted by external force, these bonds are easily broken along a specific direction, causing the material to be brittle. Once a crack occurs, it will quickly expand along the weak surface in the crystal structure, making it difficult to absorb energy through plastic deformation, making the tool easily damaged under impact load.

[0006] Therefore, it is necessary to propose a CBN composite material that can be used to process ductile iron to solve the above problems. Summary of the invention

[0007] The object of the present invention is to solve the problems mentioned in the above background technology and to provide a CBN composite material for machining ductile iron.

[0008] In order to achieve the above-mentioned purpose, the present invention specifically adopts the following technical solutions:

[0009] A CBN composite material for machining ductile iron, comprising TiC: 25-30%, Al: 5.0-12%, Ti: 2.0-8.0%, Y 2 O 3 : 2.0-4.0%, Co: 4.0-6.0%, W: 1.8-2.2%, TaC: 2.0-8.0%, the above binder particle size is 1-4um particles, and the rest are CBN particles with a particle size of 1-2um;

[0010] The CBN composite material capable of processing ductile iron comprises the following steps:

[0011] S1. Mixing: Place the above components in a three-dimensional mixer and mix them evenly for 15-22 hours. After mixing, place them in an oven and bake them at 60-80° C. for 1-2 hours to obtain a mixture.

[0012] S2, adobe block making: pour the mixture into a block mold, select a molybdenum cup with a diameter of D14 to D60 and a thickness of 1.5±0.1, and a hard alloy block with a diameter of D14-D60 for assembly, and use hydraulic equipment to press the mixture in the mold into a round cake block;

[0013] S3, assembling the matching mold: assemble the booster, graphite sheet, graphite tube, molybdenum sheet, CBN mixed powder, cemented carbide, and molybdenum cup containing round cake blocks together, then load them into the pyrophyllite module, and then place them in the six-sided top press, and adjust the six-sided top press to pre-tighten;

[0014] S4, sintering: the pre-compressed six-sided top press is sintered. In the first stage, the pressure is increased to 66Mpa, and the temperature is sent to 1300-1500℃. The pressure is kept constant for 1 minute during the temperature sending. Then, in the second stage, the pressure is increased to 88-90Mpa, and the temperature is kept constant. The sintering is carried out for 11-14 minutes, and finally the pressure is released and the temperature is reduced to room temperature to obtain a composite material block;

[0015] S5. Grinding: Use a grinder to perform double-sided rough grinding on the composite material block to grind the thickness to 4.9±0.05, then plane grind the upper surface of the composite material block, the CBN thickness is 0.9-1, the total thickness is 4.65±0.1, then double-sided fine grinding to 4.55±0.05, the CBN surface roughness Ra≤0.125, and finally plane grinding to grind and thin the cemented carbide layer to a total thickness of 1.6±0.03, that is, the finished CBN composite material is obtained.

[0016] Preferably, during the mixing step S1, the indoor temperature is controlled at 20-30°C and the humidity is maintained at 40%RH-50%RH.

[0017] Preferably, the density of the round cake briquette obtained in step S2 is 3.78 g / cm 3 .

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1. The hardness, cutting length and cutting speed of the CBN composite material made by this component and production step are improved, among which: the added Y 2 O3 It can be adsorbed on the surface of CBN particles at the microscopic level, thereby inhibiting the growth of CBN particles. It can also be pinned at the grain boundaries to hinder the migration of grain boundaries, so that the composite material can still maintain a fine grain structure at high temperatures and maintain good high-temperature performance, thereby improving the high-temperature hardness and strength of the composite material, ensuring that the tool can still maintain good cutting performance during high-temperature cutting.

[0020] 2. Ti material is added to the components. Ti atoms can form Ti-B and Ti-N bonds with B and N atoms on the surface of CBN. These chemical bonds tightly connect the CBN particles together to form a continuous and tight network structure, which wraps the CBN particles and solves the problem that the CBN particles are not firmly bonded and are easily separated and fallen off under the action of cutting force. At the same time, Y 2 O 3 The fine particles are evenly distributed at the interface, preventing the coarsening of atoms and the formation of defects at the interface, making the bonding interface denser and enhancing the bonding strength between the binder and CBN. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the present invention when assembling the matching mold;

[0022] Figure 2 It is a schematic diagram of the finished CBN composite material of the present invention. DETAILED DESCRIPTION

[0023] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0024] Embodiment 1:

[0025] By mass percentage, the components are TiC: 25%, Al: 8%, Ti: 8%, Y 2 O 3 : 3%, Co: 5%, W: 2%, TaC: 5%, CBN particles: 44%, wherein the binder particle size is 2um particles, and the CBN particles are 2um in size;

[0026] A CBN composite material capable of machining ductile iron comprises the following production steps:

[0027] S1, mixing: placing the above components in a three-dimensional mixer for uniform mixing, the mixing time is 22 hours, the temperature during mixing is controlled at 20°C, the humidity is maintained at 40%RH, after mixing, placing it in an oven for baking, the temperature is maintained at 75°C, and baking for 2 hours to obtain a mixture;

[0028] S2, adobe block making: pour the mixture into a block mold, select a molybdenum cup with a diameter of D33.4 and a thickness of 1.5, and a hard alloy block with a diameter of D33 for assembly, and use hydraulic equipment to press the mixture in the mold into a round cake block;

[0029] S3, assemble the matching mold: assemble the booster, graphite sheet, graphite tube, molybdenum sheet, CBN mixed powder, cemented carbide, and molybdenum cup containing round cake blocks together, then put them into the pyrophyllite module, and then place them in the six-sided top press, adjust the six-sided top press to pre-tighten, and refer to the assembly structure Figure 1 ;

[0030] S4, sintering: the six-sided top press after pre-compression was sintered. In the first stage, the pressure was increased to 66Mpa and the temperature was sent to 1450℃. The pressure was kept constant for 1 minute during the temperature sending. Then the second stage was carried out. The pressure was increased to 88Mpa and the temperature was kept constant. The sintering was carried out for 13 minutes. Finally, the pressure was released and the temperature was reduced to room temperature. The density was 3.78g / cm 3 Composite material blocks;

[0031] S5, grinding: Use a grinder to perform double-sided rough grinding on the composite material block, grind the thickness to 4.9, then plane grind the upper surface of the composite material block, the CBN thickness is 0.9, the total thickness is 4.65, then double-sided fine grinding to 4.55, the CBN surface roughness Ra is 0.125, and finally plane grinding is performed to grind and thin the cemented carbide layer to a total thickness of 1.6, and the finished CBN composite material is obtained. Figure 2 .

[0032] Embodiment 2:

[0033] By mass percentage, the components are TiC: 27%, Al: 5%, Ti: 4%, Y 2 O 3 : 2%, Co: 4%, W: 2%, TaC: 4%, CBN particles: 52%, wherein the binder particle size is 2um particles, and the CBN particles have a particle size of 2um.

[0034] The production steps remain the same as in Example 1.

[0035] The difference between Example 2 and Example 1 is that the proportion of CBN particles in the total amount is increased, the proportion of the binder in the total amount is reduced, and the proportions of each component of the binder are adjusted, and the other steps remain unchanged from Example 1.

[0036] Embodiment 3:

[0037] By mass percentage, the components are TiC: 28%, Al: 5%, Ti: 8%, Y 2 O 3 : 4%, Co: 4%, W: 2%, TaC: 3%, CBN particles: 46%, wherein the binder particle size is 2um particles, and the CBN particles are 2um in size;

[0038] The production steps remain the same as in Example 1.

[0039] The difference between Example 3 and Example 1 is that the proportion of CBN particles in the total amount is increased, the proportion of the binder in the total amount is reduced, and the proportions of each component of the binder are adjusted, and the other steps remain unchanged from Example 1.

[0040] Comparative Example 1:

[0041] By mass percentage, the components are TiC: 38%, Al: 7%, Co: 4%, W: 2%, CBN particles: 49%, wherein the binder particle size is 8um, and the CBN particle size is 6um;

[0042] The production steps are as follows:

[0043] S1, mixing: placing the above components in a three-dimensional mixer and mixing them evenly for 10 hours to obtain a mixture;

[0044] S2. Sintering: The mixture is subjected to spark plasma sintering. The sintering pressure is 90 MPa, the sintering temperature is 1500° C., and the sintering time is 50 min.

[0045] The difference between Comparative Example 1 and Example 1 is that Comparative Example 1 uses a conventional CBN composite material binder and conventional production steps.

[0046] Comparative Example 2:

[0047] According to mass percentage, the components are TiC: 38%, Al: 7%, Co: 4%, W: 2%, CBN particles: 49%, wherein the particle size of the binder is 2-8um, and the particle size of the CBN particles is 2-6um;

[0048] The production steps remain the same as in Example 1.

[0049] The difference between Comparative Example 2 and Example 1 is that Comparative Example 2 uses a conventional CBN composite material binder, and the production steps remain the same as those of Example 2.

[0050] The following is a comparative analysis of Example 1, Example 2, Example 3, Comparative Example 1 and Comparative Example 2, and the comparison indicators are hardness, cutting speed and cutting length.

[0051] Table 1 Performance comparison

[0052]

[0053] As can be seen from Table 1, the hardness, cutting speed and cutting length of Example 1 produced using the present components and production steps are better than those of other embodiments, and the strength of Examples 1, 2 and 3 is better than that of Examples 1 and 2 using conventional materials. At the same time, the various properties of Comparative Example 2 using the present production steps are better than those of Comparative Example 1 using conventional steps.

[0054] The CBN composite material made by using this binder ratio has improved hardness, cutting speed and cutting length, and can be used for the production and processing of ductile iron. 2 O 3 It can also be pinned at the grain boundaries to hinder the migration of grain boundaries, so that the composite material can still maintain a fine grain structure at high temperatures and maintain good high-temperature performance. At the same time, Ti atoms make the bonding interface denser, enhance the bonding strength between the binder and CBN, and indirectly enhance the strength of the CBN composite material.

[0055] In summary, the CBN composite material made using the present component binder is better than the CBN composite material made using the conventional binder, and the present production step can also simultaneously improve the performance of the CBN composite material.

Claims

1. A CBN composite material for machining ductile iron, characterized in that: According to mass percentage, the components are TiC: 25-30%, Al: 5.0-12%, Ti: 2.0-8.0%, Y2O3: 2.0-4.0%, Co: 4.0-6.0%, W: 1.8-2.2%, TaC: 2.0-8.0%, the particle size of the above binders are all 1-4um particles, and the rest are CBN particles with a particle size of 1-2um; The CBN composite material capable of processing ductile iron comprises the following steps: S1. Mixing: Place the above components in a three-dimensional mixer and mix them evenly for 15-22 hours. After mixing, place them in an oven and bake them at 60-80° C. for 1-2 hours to obtain a mixture. S2, adobe block making: pour the mixture into a block mold, select a molybdenum cup with a diameter of D14 to D60 and a thickness of 1.5±0.1, and a hard alloy block with a diameter of D14-D60 for assembly, and use hydraulic equipment to press the mixture in the mold into a round cake block; S3, assembling the matching mold: assemble the booster, graphite sheet, graphite tube, molybdenum sheet, CBN mixed powder, cemented carbide, and molybdenum cup containing round cake blocks together, then load them into the pyrophyllite module, and then place them in the six-sided top press, and adjust the six-sided top press to pre-tighten; S4, sintering: the pre-compressed six-sided top press is sintered. In the first stage, the pressure is increased to 66Mpa, and the temperature is sent to 1300-1500℃. The pressure is kept constant for 1 minute during the temperature sending. Then, in the second stage, the pressure is increased to 88-90Mpa, and the temperature is kept constant. The sintering is carried out for 11-14 minutes, and finally the pressure is released and the temperature is reduced to room temperature to obtain a composite material block; S5. Grinding: Use a grinder to perform double-sided rough grinding on the composite material block to grind the thickness to 4.9±0.05, then plane grind the upper surface of the composite material block, the CBN thickness is 0.9-1, the total thickness is 4.65±0.1, then double-sided fine grinding to 4.55±0.05, the CBN surface roughness Ra≤0.125, and finally plane grinding to grind and thin the cemented carbide layer to a total thickness of 1.6±0.03, that is, the finished CBN composite material is obtained.

2. The CBN composite material for machining ductile iron according to claim 1, characterized in that: During the mixing step S1, the indoor temperature is controlled at 20-30° C. and the humidity is maintained at 40% RH-50% RH.

3. The CBN composite material for machining ductile iron according to claim 1, characterized in that: The density of the round cake briquette obtained in step S2 is 3.78 g / cm 3 .

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