JP2023130938A - Pulverizing, stirring, mixing, and kneading machine members - Google Patents

Abstract

To improve impact resistance of pulverizing, stirring, mixing, and kneading machine members and enhance corrosion resistance of them, which are composed of cermets, disclosed in Patent Publication No. 6922110.SOLUTION: The present invention relates to pulverizing, stirring, mixing, and kneading machine members composed of cermets, which are produced by blending raw materials to have the elemental mass proportions of Ti: 15-40%, Mo: 2-29%, Cr: 1-15%, and C: 2-20%, with the combined total for Co and Ni being 30-55%, and the Co/Ni ratio being greater than 1, mixing them into mixed powder, molding the mixed powder into a pressed body, and sintering the pressed body. The cermets include three phases: a core phase 2 primarily composed of TiCN, a rim phase 3 surrounding the core phase, primarily composed of (Ti, Mo, Cr)(C, N), and a metallic phase 4. SEM observations do not reveal presence of a Mo2C phase and a chromium carbide phase.SELECTED DRAWING: Figure 1

Description

The present invention relates to a crushing, stirring, mixing, and kneading machine member made of cermet having excellent impact resistance, abrasion resistance, and corrosion resistance.

In Patent Document 1, the present inventors disclosed a crushing, stirring, mixing, and kneading machine member made of cermet with excellent impact resistance and wear resistance. In other words, the cermet, which is magnetic, lightweight, and has significantly improved wear resistance and impact resistance, obtained by the technology of Patent Document 1, can be used to extend the life of grinding, stirring, mixing, and kneading machine parts that are subject to severe wear and tear. It has become possible to extend the lifespan.

Patent No. 6922110

When the present inventors prototyped and tested a crushing, stirring, mixing, and kneading machine member made of the cermet disclosed in Patent Document 1, it was found that further improvement in impact resistance was desired. It was also found that improved corrosion resistance is desired depending on the application. That is, when used for kneading materials containing metal corrosive materials such as cathode materials for lithium ion batteries and flame retardants for plastics, high corrosion resistance is required.

Therefore, an object of the present invention is to improve the impact resistance of a crushing, stirring, mixing, and kneading machine member made of the cermet disclosed in Patent Document 1, and to provide high corrosion resistance.

The present inventors decided to incorporate Cr in order to solve the above problems, and further considered the balance with other physical properties such as wear resistance and magnetism required for parts of crushing, stirring, mixing, and kneading machines. The composition of the cermet was reconstructed for parts of crushing, stirring, mixing, and kneading machines.

That is, in the present invention, the mass ratio of each element is
Ti: 15-40%
Mo: 2-29%
Cr: 1-15%
C: 2-20%
Co and Ni total 30-55%
and a Co/Ni ratio of more than 1, any selected from Ti or Ti compounds, Mo or Mo compounds, Cr or Cr compounds, Co or Co compounds, Ni or Ni compounds, and carbon, carbides, or carbonitrides. Using powders selected as raw materials, mixing them wet or dry to obtain a mixed powder; press-molding the mixed powder at a pressure of 50 to 300 MPa to obtain a pressed body; ℃, vacuum, reduction, inert gas, hydrogen or nitrogen atmosphere, and has Ti(C,N) (including the case where N=0) as the main component. A core phase, a rim phase which exists around the core phase and whose main components are (Ti, Mo, Cr) (C, N) (including the case where N=0), and a metal phase. The above-mentioned problem was solved by providing a crushing, stirring, mixing, and kneading machine member made of cermet that has a phase and in which a Mo ₂ C phase and a chromium carbide phase cannot be observed by SEM observation.

According to the present invention, it is possible to improve the impact resistance of crushing, stirring, mixing, and kneading machine parts made of the cermet disclosed in Patent Document 1, as well as imparting high corrosion resistance. It has become possible to extend the life of the
Examples of parts for crushing, stirring, mixing, and kneading machines include screw elements and barrels for twin-screw extruders, crushing pins for pin mills, paddles for mixers, and parts for powder processing equipment such as bead mills. It can be suitably used.

FIG. 2 is a schematic diagram of a cross-sectional structure of a cermet used in the crushing, stirring, mixing, and kneading machine member of the present invention. FIG. 2 is a schematic diagram of a cross-sectional structure of a cermet having a phase containing a relatively large amount of Mo in the rim phase, which is used in the crushing, stirring, mixing, and kneading machine member of the present invention. SEM observation image of the cermet used in the crushing, stirring, mixing, and kneading machine parts of Example 1.

The crushing/stirring/mixing/kneading machine member of the present invention can be implemented as follows.

First, the mass ratio of each element is
Ti: 15-40%
Mo: 2-29%
Cr: 1-15%
C: 2-20%
Co: 10-50%
Co and Ni total 30-55%
and a Co/Ni ratio of more than 1, any selected from Ti or Ti compounds, Mo or Mo compounds, Cr or Cr compounds, Co or Co compounds, Ni or Ni compounds, and carbon, carbides, or carbonitrides. The raw material is powder selected from
For example, Ti compounds include carbides, nitrides, carbonitrides, and composite carbonitrides such as TiC, TiN, TiCN, (Ti, Mo) (C, N), (Ti, W) (C, N). It may be in any form. The same applies to Mo, Cr, Co, and Ni. Further, as the carbon (C) source, carbon, carbide, or carbonitride can be used.
Then, they are mixed wet or dry to obtain a mixed powder, and the mixed powder is press-molded at a pressure of 50 to 300 MPa to obtain a pressed body. By sintering in an atmosphere of active gas, hydrogen, or nitrogen, a pulverizing, stirring, mixing, and kneading machine member made of cermet is obtained. This cermet has three phases: a core phase, a rim phase, and a metal phase, and the specific design of each phase will be explained below. In addition, in the following explanation, all mass ratios for each element are at the raw material stage.

(Design of core phase and rim phase)
When the C content is 2 to 20%, sinterability is improved and a hard phase consisting of a fine core phase and a rim phase is formed. If C is less than 2%, a sufficient volume of core phase and rim phase will not be generated, resulting in decreased wear resistance. On the other hand, when more than 20% of C is added, a free carbon phase is generated, and the mechanical properties (strength, hardness, impact resistance) are significantly reduced, and the corrosion resistance is also reduced.
Although it is not necessary to add N, when adding N, it can be added arbitrarily within a range of more than 0 and less than 5%. By adding N, the thickness of the rim phase tends to become smaller, improving wear resistance and impact resistance. Further, by controlling N to 5% or less, it is possible to suppress the pores remaining in the alloy due to nitrogen gas generated during sintering, and it is possible to improve mechanical properties.
Furthermore, it is desirable that C:N=7:3 to 10:0. By setting the C:N ratio within this range, good wettability between the metal phase and the hard phase consisting of the core phase and the rim phase can be maintained, and denseness can be improved.
Mo is mixed in a range of 2 to 29%. Although the wettability of TiCN forming the core phase and Co and Ni forming the metal phase is poor, the rim phase generated by adding Mo ₂ C etc. improves the wettability of the hard phase consisting of the core phase and rim phase. Wettability can be improved. This increases the sinterability of the material and improves its mechanical properties. Moreover, addition of Mo is also effective from the viewpoint of improving corrosion resistance. On the other hand, if more than 29% of Mo is added, the impact resistance will decrease.Cr is mixed in a range of 1 to 15%. If Cr is less than 1%, sufficient corrosion resistance cannot be obtained. On the other hand, when Cr is added in an amount greater than 15%, wear resistance and magnetism decrease.
The total amount of Cr and Mo (Cr+Mo) is preferably 3 to 30%. Corrosion resistance improves as the amount of (Cr+Mo) increases, but if it exceeds 30%, there is a risk that abnormal phases will appear and impact resistance will decrease.
W may not be added, but if W is added, it can be added arbitrarily within a range of more than 0 and less than 10%. By adding W, wear resistance can be further improved. This is because the hard phase consisting of the core phase and the rim phase is solid solution strengthened by W atoms, making it difficult for the hard phase to break during abrasive wear.
Note that when the total content of Mo and W is 35% or less, alloys of W and Co, Mo and Co, or W, Mo and Co are not formed, and the impact resistance is further improved.

(Design of metallic phase)
The total amount of Co and Ni is 30 to 55%. If the amount of metal is less than this range, the impact resistance will be insufficient. If the amount is too high, the abrasion resistance decreases, and the parts of the crushing, stirring, mixing, and kneading machines become severely worn.
Further, the Co/Ni ratio is greater than 1. By adding a large amount of Co, which has better mechanical properties (hardness, wear resistance) than Ni, the mechanical properties of the crushing, stirring, mixing, and kneading machine members can be improved. Coupled with the effect of improving corrosion resistance due to the addition of Cr and Mo, the life of the crushing, stirring, mixing, and kneading machine members can be extended.
Furthermore, a cermet containing 30% or more of Co and Ni in total has sufficient magnetism required for magnetic separation. Magnetic separation is used in crushing, stirring, mixing, and kneading equipment to detect foreign substances in materials due to chipping of parts, etc.

The crushing/stirring/mixing/kneading machine member of the present invention can be manufactured by the following manufacturing method, for example.
(Production method)
When manufacturing the crushing, stirring, mixing, and kneading machine member of the present invention, the following steps (processes) are included.
In other words, the mass ratio of each element is
Ti: 15-40%
Mo: 2-29%
Cr: 1-15%
C: 2-20%
Co and Ni total 30-55%
and a Co/Ni ratio of more than 1, any selected from Ti or Ti compounds, Mo or Mo compounds, Cr or Cr compounds, Co or Co compounds, Ni or Ni compounds, and carbon, carbides, or carbonitrides. The raw material is powder selected from
mixing them wet or dry to obtain a mixed powder;
Press-molding the mixed powder at a pressure of 50 to 300 MPa to obtain a pressed body;
This is a step of sintering the pressed body at 1300 to 1700° C. in vacuum, reducing, inert gas, hydrogen, or nitrogen atmosphere.
In the case of wet mixing, a volatile solvent such as ethanol is used as the solvent, and the slurry is dried by vacuum standing drying, spray drying, or the like. At this time, the particle size of the particles forming the core phase and rim phase after mixing the raw materials (hereinafter referred to as "particle size before sintering") is determined according to the target value of the average particle size of the hard phase after sintering. Adjust accordingly. For example, when the target value of the average particle size of the hard phase after sintering is less than 3 μm, the particle size before sintering may be 2.0 μm or less, preferably 1.5 μm or less, more preferably 1.0 μm or less. It is good if it is 0 μm or less, more preferably 0.6 μm or less. Generally, particles grow due to sintering, but if the particle size before sintering is 2.0 μm or less, the generation of coarse hard particles can be suppressed, and if the particle size is 1.5 μm or less, The average particle size of the hard phase after sintering can be easily made less than 3 μm. If it is 1.0 μm or less, the average particle size of the hard phase after sintering becomes smaller and wear resistance improves. Furthermore, if it is 0.6 μm or less, it becomes possible to sinter at a lower temperature, and the wear resistance can be further improved.
On the other hand, when the average particle size of the hard phase after sintering is 3 μm or more, it is sufficient to use a large raw material powder for the core phase, or to not grind the raw material powder or to grind it for a short time, for example. , the grain size before sintering may be 2 μm or more.
A resin component serving as a molding binder is mixed with the obtained raw material mixed powder and granulated. Spray drying may be used for granulation.
The granulated powder is press-molded at 50 to 300 MPa using a die press or isostatic press. After molding, intermediate processing may be performed as necessary.
As for the sintering conditions, main sintering is performed in a vacuum or gas atmosphere at 1300 to 1700°C. A degreasing/temporary sintering step may be performed before the main sintering, and intermediate processing may be performed as necessary at each stage after degreasing and after the preliminary sintering. The degreasing and pre-sintering steps may be performed continuously, and the degreasing and pre-sintering steps and main sintering may also be performed continuously. When performing degreasing and temporary sintering, it is performed in a vacuum or gas atmosphere at 600 to 1000°C. Furthermore, hot hydraulic pressing can be performed if necessary.
Finally, it is finished into the final shape by mechanical processing or electrical processing to obtain the desired crushing, stirring, mixing, and kneading machine parts.

(Structure of cermet used for crushing, stirring, mixing, and kneading machine parts)
The structure of the cermet used in the present invention is confirmed by cross-sectional observation using SEM.
As the cross-sectional structure 1 of the above cermet is schematically shown in FIG. It exists so as to cover the core phase 2 as a component, and (Ti, Mo, Cr) (C, N) (including the case where N=0. In other words, when it does not contain N, (Ti , Mo, Cr)C) and a metal phase 4, and the cermet does not contain a Mo ₂ C phase or a chromium carbide phase in principle. When a Mo ₂ C phase and a chromium carbide phase are present, in SEM (scanning electron microscopy) observation, they exist in the metal phase in the form of particles with different brightness in addition to the core phase and rim phase. If you are unsure, perform analysis using EPMA (electron beam microanalyzer), EDX (energy _dispersive to decide. Even when observed irregularly, the number of particles of 1 μm or more is 1 or less in the 10,000-fold observation field, and the number of particles of 0.3 μm or more is 5 or less. In addition, in the present invention, "the Mo ₂ C phase and the chromium carbide phase cannot be observed by SEM observation" means that there is one particle or less of 1 μm or more in the observation field of 10,000 times as described above, and also 0. This also includes cases where the number of particles of 3 μm or more is 5 or less.
With the above configuration, a material with high impact resistance and abrasion resistance can be obtained.

Further, the above cermet has the following characteristics.
(core phase)
The core phase is a hard phase containing Ti(C,N) (including the case where N=0) as a main component, and has high hardness.
(rim phase)
The rim phase exists so as to surround the core phase, and has (Ti _, Mo, Cr) (C, N) (including the case where N=0) as the main components. As shown in FIG. 2, the rim phase may have two phases: a phase with a relatively large amount of Mo component and a phase with a relatively large amount of Ti. In the case of two phases, the hardness of the rim phase is improved and the wear resistance becomes higher.
(Particle size)
The average particle size of the hard phase consisting of the core phase and the rim phase is not particularly limited, but the average particle size of the hard phase can be calculated from the Fruman equation (Equation 1) below by observing the cross-sectional structure of the cermet with an SEM. .
[Number 1]
d _m = (4/π)×(N _L /N _S ) (Formula 1)
N _L = n _L /L (Formula 2)
N _S = n _S /S (Formula 3)
In (Equation 1), _dm is the average particle diameter, π is pi, N _L is the number of particles per unit length hit by an arbitrary straight line on the cross-sectional structure, and N _S is the number of particles per unit length hit by an arbitrary straight line on the cross-sectional structure. It represents the number of particles included, in (Equation 2), _nL represents the number of particles hit by an arbitrary straight line on the cross-sectional structure, L represents the length of an arbitrary straight line on the cross-section structure, and (Equation 3 ), n _S represents the number of particles contained within an arbitrary measurement area, and S represents the area of the arbitrary measurement region.

The average particle size of the hard phase consisting of the core phase and the rim phase can be less than 3 μm. By setting the average particle size of the hard phase to less than 3 μm, hardness and wear resistance are improved. In particular, by setting the average particle size of the hard phase to 1.5 μm or less, the hardness is further improved and the wear resistance is further improved.
On the other hand, the average particle size of the hard phase can also be set to 3 μm or more. By setting the average particle size of the hard phase to 3 μm or more, fracture toughness is improved.
In this way, the average particle size of the hard phase may be appropriately determined depending on the specific use (required characteristics). In addition, when the average particle size of the hard phase is set to 3 μm or more, the upper limit of the average particle size is not particularly limited and may be determined within the range of common technical knowledge, but for example, it is 10 μm or less. be able to. Note that when the average particle size of the hard phase after sintering is 3 μm or more and 10 μm or less, the particle size before sintering may be 2 μm or more and 7 μm or less, for example.

(specific gravity)
The crushing/stirring/mixing/kneading machine member according to this embodiment has a specific gravity of 9 or less. Conventionally, crushing, stirring, mixing, and kneading machines have been designed with the assumption that they will be equipped with parts made of steel, so if the specific gravity of the parts exceeds 9, the rotating shaft may deflect, causing damage to the drive unit. This may cause an increase in load, etc. When the specific gravity is 8 or less, it can be treated in the same way as steel materials, and when the specific gravity is 7.5 or less, it is lighter than steel materials, which increases the degree of freedom in device design.

Cermets with the above characteristics have wear resistance equivalent to or higher than cemented carbide, specific gravity equivalent to steel materials, and furthermore have magnetism and high impact resistance and corrosion resistance. By applying this material as a component for a crusher, stirrer, mixer, or kneader, damage caused by contact between components and wear and corrosion of the component during use can be suppressed, and the life of the component can be extended.

First, the raw material powder shown in Example 1 in Table 1 was pulverized and mixed using an attritor or a ball mill using ethanol as a solvent. The obtained slurry was dried in a vacuum, paraffin as a binder was mixed therein, and a pressed body was produced by press molding.
This pressed body is pre-sintered at 800°C in an atmospheric pressure hydrogen atmosphere, and then main sintered at 1400°C in a vacuum atmosphere to produce a cermet used in the crushing, stirring, mixing, and kneading machine parts of the present invention. I got it.
The cermet obtained in Example 1 had an average particle diameter of 1.13 μm as calculated by the above-mentioned Fruman formula.
Examples after Example 2 and comparative examples were sintered at the lowest temperature within the range of 1300 to 1500°C at which the highest density was obtained. Other conditions were the same as in Example 1.
Further, in Examples 1 to 13 and all comparative examples, the average particle size of the hard phase consisting of the core phase and the rim phase was less than 1.5 μm. On the other hand, in Examples 14 and 15, the average particle size of the hard phase consisting of the core phase and the rim phase was about 5 μm. Note that Comparative Example 1 corresponds to "Example 1" shown in Table 1 of Patent Document 1 mentioned above.
Furthermore, when the constituent components of the cermet cross-sectional structure were observed by SEM observation, the presence of Mo ₂ C phase, chromium carbide phase, and WC phase could not be confirmed in all Examples. In addition, in all Examples, a phase containing a relatively large amount of Mo was present in the rim phase.

The elemental composition ratio of the entire cermet structure had a large deviation from the raw material composition, and the coefficient of determination between the raw material composition and the component ratio of the cermet after sintering was low, so it was not possible to quantify it accurately. As explained in the above-mentioned Patent Document 1, the reason for this is thought to be that the change in the lattice state due to the formation of a solid solution between the constituent elements is affected. That is, as stated in the non-patent document 1 (Kawabata, Fujimura, Chitoku, "Powder and Powder Metallurgy" Vol. 29, No. 1 (1980), 30-34) cited in Patent Document 1 above, past research also It is known that quantifying the alloy composition of cermet materials is difficult, and accurate quantification is difficult.
As described above, in the present invention, it is impossible or almost impractical to directly specify the object by its structure or characteristics, and the present invention has so-called "impossible/impractical circumstances". exist.

Subsequently, the characteristics of the produced cermet were evaluated using the measurement method shown below.
*Specific gravity: Archimedes method (standard: JIS Z 8807)
*Hardness: Vickers hardness test (standard: JIS Z 2244)
*Abrasion resistance...Rubber wheel test (Standard: ASTM G65)
*Impact resistance: Charpy impact test using a 10R notched test piece
(Standard: JIS Z 2242)
*Fracture toughness value...JIS R 1607 (IF method)
*Magnetism: Saturation magnetization measurement *Corrosion resistance: A 24-hour immersion test at room temperature in an acidic solution, and the depth to which corrosion has progressed can be determined from the amount of weight loss before and after the test and the shape and specific gravity of the test piece. calculation

Table 3 shows the properties of the cermets in Examples and Comparative Examples of the present invention.
Here, the evaluation criteria for impact resistance (Charpy impact value) and corrosion resistance were determined to be higher than "Comparative Example 1", which is the cermet disclosed in Patent Document 1, as a passing level. Furthermore, the evaluation criteria for wear resistance and magnetism were determined to be equivalent to or higher than that of cemented carbide (JIS classification: V40 equivalent material).

In all Examples, the impact resistance and corrosion resistance exceeded that of "Comparative Example 1", which is the cermet disclosed in Patent Document 1, and showed excellent impact resistance and corrosion resistance. In addition, the specific gravity was kept below the target of 9, and both were lower than the specific gravity of SKD (7.7). In addition, the wear resistance was equivalent to or higher than that of cemented carbide (JIS classification: V40 equivalent material).
In addition, in Example 5 in which the amount of W added is 10% or more, the effect of improving impact resistance is lower than in other Examples. Further, even in Examples 3 and 4 in which the amount of W added is 6% or more, the effect of improving impact resistance is slightly lower than in other Examples. This shows that when W is added, the amount added is preferably less than 10%, more preferably less than 6%. Note that, as demonstrated in Examples 12 and 13, W may not be added to the cermet of the present invention. Furthermore, as demonstrated in Examples 14 and 15, it can be seen that fracture toughness is improved by setting the average particle size of the hard phase to 3 μm or more.

Comparative Example 1 is the cermet disclosed in Patent Document 1, and the impact resistance and corrosion resistance were insufficient.
In Comparative Example 2, the corrosion resistance decreased because the amount of Cr added was small.
In Comparative Example 3, the wear resistance and saturation magnetization decreased due to the large amount of Cr added.
In Comparative Example 4, since the amount of Mo added was small, the wear resistance and saturation magnetization decreased.
In Comparative Example 5, the impact resistance decreased because the amount of Mo added was large.
In Comparative Example 6, since the Co/Ni ratio was 1 or less, the wear resistance and saturation magnetization decreased.
In Comparative Example 7, the amount of metal phase (Co+Ni) was large, so the wear resistance decreased.
In Comparative Example 8, the impact resistance decreased because the amount of metal phase (Co+Ni) was small.

FIG. 3 shows an SEM observation image of the cermet of Example 1. The darkest part is the core phase, the second darkest part is the rim phase, and the lightest part is the metal phase.

1 Cross-sectional structure of cermet 2 Core phase 3 Rim phase 4 Metal phase 5 Relatively Mo-rich phase

Claims (3)

The mass ratio of each element is
Ti: 15-40%
Mo: 2-29%
Cr: 1-15%
C: 2-20%
Co and Ni total 30-55%
and a Co/Ni ratio of more than 1, any selected from Ti or Ti compounds, Mo or Mo compounds, Cr or Cr compounds, Co or Co compounds, Ni or Ni compounds, and carbon, carbides, or carbonitrides. The raw material is powder selected from
mixing them wet or dry to obtain a mixed powder;
Press-molding the mixed powder at a pressure of 50 to 300 MPa to obtain a pressed body;
A crushing, stirring, mixing, and kneading machine member made of a cermet obtained by sintering a pressed body at 1300 to 1700°C in a vacuum, reducing, inert gas, hydrogen, or nitrogen atmosphere. ,
There is a core phase whose main component is Ti (C, N) (including the case where N = 0), and a core phase that surrounds the core phase and contains (Ti, Mo, Cr) (C, N) (N = 0) has three phases, a rim phase whose main component is a metal phase, and a metal phase.
A pulverizing, stirring, mixing, and kneading machine member made of cermet in which no Mo ₂ C phase or chromium carbide phase can be observed by SEM observation. The crushing, stirring, mixing, and kneading machine member made of the cermet according to claim 1, wherein the mass ratio of Cr and Mo in the raw materials is 3 to 30% in total. A claim in which the ratio ((Co+Ni)/(Cr+Mo)) of the sum of the mass ratios of Cr and Mo in the raw materials to the sum of the mass ratios of Co and Ni in the raw materials (Co+Ni) is 0.24 to 1. A crushing, stirring, mixing, and kneading machine member made of the cermet according to claim 1 or claim 2.