JPH0860278A - Corrosion and abrasion resistant material with excellent cavitation erosion resistance - Google Patents

Abstract

PURPOSE: To produce a composite material excellent in cavitation resistance as well as corrosion resistance and wear resistance. CONSTITUTION: This composite material is the one in which granular Ni-base alloys are dispersed into the spaces of hard phases essentially consisting of fine carbides and having a componental compsn. contg., in total, by weight, 0.4 to 1% B, 1.5 to 7% C, 3 to 7% Si, 3 to 21% Ti, 8 to 16% Cr, 2 to 5% Fe, 0.3 to 0.7% Sn, 5 to 25% W, O to 3% Cu, and the balance Ni with inevitable impurities. Thus, excellent characteristics can be obtd. in all of corrosion resistance, wear resistance and cavitation resistance, and excellent durability as that of the constituting sliding material of a resin working machine used in a severe environment or the like can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a composite material having excellent corrosion resistance, abrasion resistance, and cavitation erosion resistance, and resin processing for plastics such as highly corrosive plastics and rubbers. Suitable for die materials, cylinder materials, screw materials, etc. of machines and food processing machines, especially for resin processing machines and food products for compounds that require cavitation erosion and corrosion resistance to hydrochloric acid, and further wear resistance. It is suitable for corrosion resistant and abrasion resistant materials such as processing machines.

[0002]

2. Description of the Related Art Die materials for granulators used in resin processing and food processing are susceptible to wear due to contact with cutter blades and damage due to cavitation erosion, and resin, cylinder materials for food processing machines, and screw materials , Easily subject to wear by the object to be machined or contact wear between metals. Therefore, these materials must be made of materials having excellent wear resistance, and conventionally, hard particles such as WC are dispersed in self-fluxing wear-resistant Ni-based alloys and Ni-based self-fluxing alloys having excellent wear resistance. A composite material is used.

[0003]

However, due to the recent enhancement of the functionality of molding materials, the environment in which resin / food processing machines are used has become more severe. For example, in molding operations under high temperature conditions, resin -It becomes very susceptible to corrosion by being exposed to the corrosive gas generated from food. Therefore, with regard to the materials constituting these machines, it is not sufficient to prioritize only wear resistance as in the conventional case, and excellent characteristics are also required for corrosion resistance.
Further, the die material of the granulator for resin processing used in water is significantly damaged by cavitation erosion, and therefore it is also required to have excellent resistance to this.

However, although the self-fluxing wear-resistant Ni-based alloy and the WC-added composite material described above have good wear resistance, they do not have sufficient cavitation erosion resistance and corrosion resistance.
On the other hand, as a material excellent in corrosion resistance, Ni-Cr-
Mo alloy and stainless steel are known, and there are examples in which they are actually used for the above-mentioned mechanical materials. However, these materials do not have sufficient wear resistance, and for example, they have a drawback that they tend to cause adhesion and galling due to contact between members. As described above, no conventional material has been found to have satisfactory properties in wear resistance, corrosion resistance, and cavitation erosion resistance. Currently, the development of materials excellent in all of these properties is in progress, but it has not been realized yet. The present invention has been made against the background of the above circumstances.
An object of the present invention is to provide a corrosion-resistant and wear-resistant material having excellent cavitation erosion resistance, which can withstand use in a highly corrosive environment in food processing machines and the like.

[0005]

In order to solve the above problems, the present inventors have focused on a hard phase mainly composed of WC-TiC composite carbide and a hard alloy in which Cr carbide is dispersed. Furthermore, in the process of developing a wear-resistant material having cavitation erosion resistance and corrosion resistance, it is softer than a hard material, contrary to the conventional material in which a hard phase such as spherical or knitted is dispersed in a Ni-based alloy matrix. The present inventors have found that the material obtained by dispersing the Ni-based alloy in the hard phase is excellent in cavitation erosion resistance and corrosion resistance, and completed the present invention.

That is, the corrosion-resistant and wear-resistant material excellent in cavitation erosion resistance of the present invention is a composite material in which granular Ni-based alloy is dispersed in the hard phase mainly composed of fine carbide, and the total composition is the total amount. B: 0.4 to 1% by weight, C: 1.5 to 7% by weight, Si: 3 to 7% by weight, T
i: 3 to 21% by weight, Cr: 8 to 16% by weight, Fe: 2
~ 5 wt%, Sn: 0.3-0.7 wt%, W: 5-2
5% by weight, Cu: 0 to 3% by weight, and the balance is Ni and inevitable impurities.

The above-mentioned hard phase is mainly composed of a carbide having a fine mixed structure of WC and TiC or reacting with the contained components. In the carbide as well, a double carbide may be formed, and further, a boride may be formed. May be included. In this hard phase, some Ni-based alloys are present as a binder phase. Further, the remaining Ni-based alloy is dispersed in a granular form between the hard phases to form an island shape, and the shape and size thereof are not limited in the present invention, but are spherical and have an average particle diameter of 50 to 50.
It is preferably 200 μm. Further, the Ni-based alloy particles may contain carbides or borides. The composition of the present invention is preferably provided as a powder and manufactured by a powder metallurgy method of sintering the composition. According to this method, a composite material in which hard materials are uniformly dispersed can be obtained. Furthermore, hot isostatic pressing method (HIP method)
By using, a composite material having higher strength and higher toughness can be obtained.

In the above powder metallurgy, W, Ti and C
All or a part of u can be provided as fine carbide such as WC and TiC, elemental metal powder and alloy powder. When the hard phase constitutes carbide, it is desirable that the grain size be 10 μm or less, and the average grain size is 2
It is more desirable to adjust the thickness to ˜4 μm. This is 2 μm
If it is less than, it is too fine and wear resistance is not fully exerted, while
This is because if it exceeds 10 μm, the effect of uniform dispersion becomes poor. And in order to obtain a better uniform dispersion effect,
As described above, it is desirable that the average particle size is 4 μm or less. Further, it is desirable that Cu has a particle size of 150 μm or less. The case where the carbide is provided as a powder is shown as an example. WC: 5.3 to 2 relative to the total amount.
6.0%, TiC: 3.7-26.3%, optionally C
u: 0.5 to 3% of fine powder is added.

When these powders are used, the mother alloy (Ni
As the base alloy) powder, one having a composition as required within the scope of the invention is used. For example, for the total amount,
B: 0.4 to 1%, C: 6% or less, Si: 3 to 7%, C
r: 8-16%, Fe: 2-5%, Sn: 0.3-0.
7%, W: 0 to 1.2%, balance Ni
Ni-based alloy powder consisting of is used. The mother alloy powder preferably has an average particle size of 50 to 200 μm,
Further, those manufactured by the atomizing method are desirable for the sake of sinterability and uniformity of structure. In this mother alloy powder, it is desirable that the above-mentioned particle size is less than 50 μm when Ni is of an appropriate size.
This is because the base alloy particles are not formed and the cavitation erosion resistance is not sufficiently improved.
This is because if m is exceeded, the hard phase will be in a state similar to that in which the hard phases are scattered at large intervals, and uniform wear resistance cannot be obtained.

The carbide powder and the master alloy powder are mixed in a predetermined amount by a ball mill or the like, and the mixed powder is molded, then generally degreased and then sintered. Degreasing is performed, for example, in a non-oxidizing atmosphere (in an inert gas or vacuum) at 350
It heats at -500 degreeC for 2 to 4 hours, and performs it. When the sintering is performed by liquid phase sintering, for example, 1000 to 105
Sinter at 0 ° C for 10-120 minutes. Sintering is preferably performed in a non-oxidizing atmosphere, and is performed in an inert gas or vacuum. The sintering method is not limited to this, and in addition to the normal sintering method, the hot isostatic pressing method (HIP method),
It is also possible to adopt another sintering method such as a hot pressing method. In addition, the sintering temperature is increased to, for example, 1100 ° C.
WC when sintering above (however, 1200 ° C or less)
Reacts with other components to form double carbides and double borides, respectively. In addition, thermodynamically stable TiC does not react and is dispersed alone in the tissue and exhibits respective properties.

The above sintering temperature is preferably 1000
This is because if the temperature is less than ℃, sufficient sintering cannot be achieved.
This is because when the temperature exceeds 1200 ° C., Ni alloy particles of an appropriate size are not formed. Further, if the sintering time is less than 10 minutes, sufficient sintering is not performed, and if it exceeds 120 minutes, the reaction proceeds and the particles become large. Incidentally, the corrosion-resistant wear-resistant material of the present invention, corrosion resistance, wear resistance,
It is suitable for use as a constituent material of resin processing machines and food processing machines that require cavitation erosion resistance. For example, dies for granulators, extrusion molding or injection molding of resins, ceramics, metals, etc. Can be used as a cylinder for molding.

[0012]

In other words, according to the corrosion-resistant and wear-resistant material of the present invention, the structure contains boride and carbide, and as a result of various experiments, boride acts as a lubricant during sliding, Mitigates the aggression against wood. In addition, boride exhibits appropriate wear resistance and improves corrosion resistance. By combining carbides such as W and Ti with the compound boride, adhesion wear between metals is reduced, and due to the wear resistance of the carbide having high hardness, it also effectively acts on abrasive wear. Therefore, according to the present invention, a material having both excellent corrosion resistance and abrasion resistance can be obtained.

In the case of damage due to cavitation erosion, it is considered that the general spherical hard particle dispersion type alloy is such that the damage of the soft matrix progresses first when the bubbles generated by the negative pressure are broken, and finally the hard material particles. Is lost, resulting in a large amount of damage to the entire material. However, in the corrosion-resistant and wear-resistant material of the present invention, a granular Ni-based alloy in which fine Cr carbides, borides and the like are dispersed is distributed in an island shape, and this island-shaped base alloy is dispersed in fine hard carbides. It has a structure covered with a hard phase. Therefore, even if the Ni-based alloy is damaged first, it is difficult for the hard material to fall off, and excellent cavitation erosion resistance is exhibited.
It is considered that such a material has a problem in strength, but since the hard phase is also bonded by the Ni-based alloy, it is comparable in strength to the conventional material.

Next, the reasons for limiting the components of the present invention will be described. B is to form a complex boride which becomes a hard phase,
It is an essential element. If the B content is less than 0.4%, the melting point of the alloy increases and wear resistance deteriorates.
If it exceeds 1%, the amount of the hard phase becomes excessive and the toughness and strength are deteriorated, so the content is made 0.4 to 1% by weight. C
, Which constitutes a hard phase as carbides of W and Ti, further reacts with Cr and the like to form carbides, which contributes to improvement of wear resistance. If the content is less than 1.5%, the wear resistance is insufficiently improved, and if it exceeds 7%, carbides become excessive, the attacking property of the mating material is increased, and the mechanical properties are impaired. The range is wt%. Si is N
It is an essential element that forms a ternary eutectic with i and B to lower the melting point of the alloy, and forms a compound with Cr, Mo, W, etc. to enhance the wear resistance of the alloy. It also has the effect of increasing the fluidity of the molten metal during atomization and making the powder particle size uniform. If it is less than 3%, the above effect is small, and if it exceeds 7%, the alloy becomes brittle, so the content is made 3 to 7% by weight.

Ti constitutes a hard phase, and if it is less than 3%, the wear resistance is insufficient, and if it exceeds 21%, the strength deteriorates, so the range is 3 to 21% by weight. Cr not only forms a carbide by reacting during sintering or forms a hard phase as a boride, but also forms a solid solution in the binder phase to improve corrosion resistance, wear resistance, heat resistance, and oxidation resistance. It has a function to make it. If the content is less than 8%, the corrosion resistance is insufficient, and if it exceeds 16%, the improvement in the corrosion resistance commensurate with the addition amount is not recognized, and the toughness also decreases, so the range is 8 to 16% by weight. To do. Fe is added to improve the strength at low temperatures. To obtain this effect, it is necessary to add 2% or more. On the other hand, if the addition amount is large, the corrosion resistance decreases, so the content is limited to the range of 2 to 5% by weight. Sn has the effect of increasing the corrosion resistance to hydrochloric acid, but if it is less than 0.3%, it has no effect, and if it exceeds 0.7%, the alloy becomes brittle, so the range is 0.3 to 0.7% by weight.

W constitutes a hard phase and reacts with other components to form double carbides and double borides. If the content is less than 5%, the wear resistance is insufficiently imparted,
If it exceeds 25%, the strength of the material deteriorates,
The range is wt%. Cu contributes to the improvement of the corrosion resistance of the Ni-based alloy, as typified by Monel (trademark) alloy, which is a Ni alloy, and is therefore added when importance is attached to the corrosion resistance.
In order to obtain this effect sufficiently, it is desirable to add 0.5% or more. However, if the addition amount is large, the alloy is softened and wear resistance is deteriorated, so the content is made 3% or less.
In addition, when importance is attached to abrasion resistance, no addition can be made. Ni is an element effective in improving the corrosion resistance and has the effect of forming a hard boride together with B to improve the wear resistance. Therefore, the balance is Ni. In addition, although there are unavoidable impurities in the balance Ni, they are
It is allowed within a range that does not impair the effects of the present invention.

[0017]

EXAMPLES Examples of the present invention will be described below in comparison with comparative materials (conventional materials). In addition, in the following description, all component amounts are shown by weight%. First, alloy A shown in Table 1 was prepared as a part of the raw material powder, and the powders were weighed in the component ratios shown in Table 2 to prepare test mixed powders (invention materials 1 to 7). The particle diameters of the respective raw material powders in the invention material are as shown below. (Particle size) Alloy A: -80 + 280 mesh WC: 2.77 μm (average particle size) TiC: 2.77 μm (average particle size) Cu: -100 mesh A predetermined amount of a binder such as paraffin is further added to each mixed powder. After wet mixing for 1 hour in a ball mill in an organic solvent, it was dried. This granulated powder was molded by the cold isostatic pressing method (CIP method). The obtained molded body was degreased by heating at 350 to 500 ° C. for 2 to 4 hours in an inert gas atmosphere, and the molded body after degreasing was sintered in a vacuum atmosphere. Specifically, the sintered body of the present invention was obtained by holding it at 1000 to 1050 ° C. for 120 minutes in an atmosphere of 0.1 MPa or less. Furthermore, by cutting this sintered body,
Test pieces (invention materials 1 to 7) having a predetermined shape were manufactured. Also,
For comparison, test pieces (comparative materials 1 and 2) made of conventional materials were prepared. Comparative material 1 was made of stainless steel, and an ingot was used as a test piece. Comparative material 2 is a composite material of Ni-based self-fluxing alloy and WC, and WC is dispersed in the Ni-based self-fluxing alloy. The manufacturing method is alloy B (particle size 50
.About.100 .mu.m) and WC (particle size 50 .mu.m) at the component ratios shown in Table 2 and produced by a dissolution method. In addition, the total amounts of the components of the invention materials 1 to 7 and the comparative materials 1 and 2 are shown in Table 3.
Shown in The above-mentioned invention material 1 was subjected to surface analysis structure observation by an EPMA (electron beam microanalyzer). As a result, as shown in the photograph of FIG.
A composition of Ni-Si-Fe-Cr was formed, and as the hard phase, a compound carbide of Ti, WC, and a boride of CrB were produced.

[0018]

[Table 1]

[0019]

[Table 2]

[0020]

[Table 3]

Next, in order to evaluate the characteristics of each test piece, its hardness was measured, and a corrosion test and an abrasion test were performed. Corrosion test, 70 ℃, hydrochloric acid (pH
= 4) for 48 hours, and the corrosion weight loss was measured to evaluate the corrosion resistance. Further, in the wear test, in order to simulate the adhesion wear between metals, the Ogoshi type rapid wear tester was used, and SUS440C (HRC56) was used as the mating material. The abrasion test was performed under the conditions of a final load of 62 N, a friction speed of 4.36 m / S, a friction distance of 200 m, room temperature and no lubrication, and the abrasion resistance was measured by measuring the abrasion amount. In addition, an abrasive wear test was conducted to simulate wear due to hard additives in the resin. Specifically, the mating material is the 320th S
Using iC polishing paper, load 20N, speed 3.6m / s (6
The test was conducted at 0 reciprocations / minute), and the amount of wear was the average value of the amount of wear reduction every 400 times. The results of these tests are shown in Table 4.
In addition, in order to quantitatively evaluate the cavitation erosion resistance of the material, a test was conducted using an opposed type magnetic vibration tester. The measurement conditions are a frequency of 20 kHz, an amplitude of 60 μm, a gap between the vibrator and the test piece of 0.4 mm, a test solution of adjusted water (pure water is adjusted to pH = 4 with hydrochloric acid), and a flow rate of the test solution of 0.2 liter / min. , The temperature of the test solution 21 to 30 ° C.,
The test time is 24 hours.

[0022]

[Table 4]

As a result, the comparative material 1 (stainless steel) is excellent in corrosion resistance but inferior in wear resistance. For example, a material suitable for molding a composite material obtained by adding glass fiber to resin. is not. Further, the comparative material 2 (Ni-based self-fluxing alloy + WC) has sufficient wear resistance, but is inferior in cavitation erosion resistance and corrosion resistance.
On the other hand, the test pieces of the invention materials 1 to 7 were Ti, W, and Cr.
The wear resistance is improved by the carbide of the above, and for example, wear due to the hard additive in the resin is prevented. Also, in the Ogoshi-type wear test, the compound boride exhibits its effectiveness as a lubricant, and the amount of wear of both itself (fixed test piece) and mating material (rotating test piece) is small, and the metal components In the wear caused by the contact between the two materials, the aggressiveness to the mating material is softened, and the adhesive wear between the metals is softened.
Furthermore, the amount of corrosion in the corrosion test is small, and for example, even in a highly corrosive environment due to the gas generated from the resin, high Cr
Ni matrix shows high corrosion resistance. Also, good results were obtained in the cavitation erosion resistance test. As described above, the material of the present invention, unlike the comparative material, was excellent in all of the wear resistance, the corrosion resistance and the cavitation erosion resistance. In Comparative Material 1 in the table, the wear amount of the rotary test piece shows a negative value because the material of the fixed test piece adheres to the rotary test piece due to adhesion.

[0024]

As described above, according to the corrosion-resistant and wear-resistant material of the present invention, since the granular Ni-based alloy is dispersed in the hard phase mainly composed of carbide, only high corrosion resistance and cavitation erosion resistance are achieved. In addition, there is an effect that excellent properties can be obtained as a wear resistant material having both properties of anti-adhesion and anti-abrasive wear. Therefore, a composite material with excellent durability can be obtained as a sliding material that is used for resin processing machines, food processing machines, and other die hardening layers used under severe molding conditions, cylinders, screws, friction rings, check rings, etc. It is effective.

[Brief description of drawings]

FIG. 1 is a photograph of a metal structure of a sintered body of Inventive Material 1.

Front page continuation (72) Inventor Toshio Matsuo 1-6-1, Funakoshi Minami, Aki-ku, Hiroshima City, Hiroshima Prefecture Japan Steel Works, Ltd.

Claims (1)

[Claims] 1. A composite material in which a granular Ni-based alloy is dispersed between hard phases containing fine carbide as a main component, and the total component composition is B: 0.4 to 1% by weight and C: 1.5. ~ 7 wt%, Si: 3-7 wt%, Ti: 3-21 wt%, C
r: 8 to 16% by weight, Fe: 2 to 5% by weight, Sn: 0.
3 to 0.7% by weight, W: 5 to 25% by weight, Cu: 0 to 3
Corrosion and abrasion resistant material having excellent cavitation erosion resistance, characterized in that the content of Ni is unavoidable and the balance is Ni.