JPS62191484A - Composite material for pump - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a composite material for pumps that has excellent corrosion resistance and wear resistance.

[Prior art]

A pump is a device that transports fluid and directly imparts kinetic energy to the fluid being transported. Therefore, pumps are the most susceptible to corrosion and wear compared to pipes, tanks, and other parts that only come into contact with fluid, and are less hydrodynamically efficient than the parts that only come into contact with fluid. All are also required equipment.

Conventionally, ordinary cast iron has been used as a material for pumps, and low-chromium cast iron is used for pumps for transporting slurry-like fluids stored in earth and sand. In the case of pumps for transporting fluids, high chromium cast iron is used. In this way, materials for pumps that transport fluids containing solid particles are selected mainly from materials with high hardness from the viewpoint of requiring wear resistance. The pH value of the fluid must be selected in consideration of the oxidation-reduction potential, etc. Therefore, such materials for pumps need to be manufactured with various chemical compositions and heat treatment conditions depending on the factors mentioned above.

Table 1 shows typical chemical compositions and hardness of ordinary cast iron, low chromium cast iron, and high chromium cast iron, which have been commonly used as materials for pumps.

[Problems with conventional technology]

As described above, materials for conventional pumps must be selected in consideration of various factors depending on the environment in which they are used, that is, the properties of the transport fluid, and this requires very advanced knowledge. Furthermore, if the material for the pump is special cast iron, such as high chromium cast iron, a certain amount of molten metal of said special cast iron must be produced in order to cast the pump parts, and for this purpose. , until a predetermined amount of the special cast iron pump parts with the same composition are manufactured.
I couldn't cast this. For this reason, casting of pump parts made of special materials requires a long period of time.

Furthermore, since it is difficult to machine pump parts made of special cast iron such as high chromium cast iron, precision casting is performed using a ceramic shell, and the resulting casting is used as pump parts as is.

Therefore, not only the preparation of the material (molten metal) but also the manufacturing process are different from other pump parts made of ordinary cast iron, for example.

As a result, when manufacturing pump parts, it is necessary to manage the manufacturing process, which varies depending on the product.
This created extremely complex administrative requirements.

[Purpose of the invention]

The object of the present invention is to provide a material for a pump that allows pump parts of various strengths to be manufactured by the same process.

[Summary of the invention]

In the composite material for a pump of the present invention, either one of an epoxy resin and a polyimide resin is impregnated and solidified into the open pores of a porous silicon carbide sintered body covering the open pores of a three-dimensional network structure. It has two characteristics.

[Structure of the invention]

The reason why porous silicon carbide sintered bodies are used in the pump composite material of this invention is that porous silicon carbide sintered bodies have extremely low shrinkage during the sintering process, can be manufactured with high strength, and have dimensional accuracy. This is because it is suitable for manufacturing pump parts that require

As starting materials for porous silicon carbide sintered bodies,
! i! However, in order to obtain a porous silicon carbide sintered body with higher strength, silicon carbide containing β-8iC as the main component can be used. should be used.

Silicon carbide with an average particle size in the range of 0.15 to 5 μm is used, but in order to obtain a high-strength porous silicon carbide sintered body suitable for composite materials for pumps, silicon carbide with a small average particle size is used. Uses silicon carbide. Note that if high strength is not required, silicon carbide with a large average particle size is used to reduce the degree of shrinkage during sintering.

The average aspect ratio of silicon carbide crystals should be 50 or less. If the average aspect ratio exceeds 50, the strength of the porous silicon carbide sintered body composed of plate-shaped crystals and the composite material for pumps will be extremely reduced, which is not preferable.

A molded body made of such silicon carbide, 1700 ~
Sintering in a non-oxidizing atmosphere at a temperature in the range of 2300°C. These dried SiC crystal particles bond with adjacent particles, thus obtaining a porous silicon carbide sintered body having a three-dimensional network structure.

If CO gas, N2 gas, or the like is used as the atmosphere during sintering, the amount of shrinkage during sintering can be reduced.

If the above-mentioned sintering temperature is less than 1700° C., the growth of particles will be insufficient and the strength of the sintered body will be reduced. On the other hand, if the sintering temperature exceeds 23oO<0>C, the sublimation of SiC will increase and the developed crystals will become thinner, which is not desirable.

Aluminum, boron, calcium, chromium, iron, lanthanum, lithium, titanium, yttrium, silicon, nitrogen,
By mixing oxygen, carbon, and at least one of these compounds into the raw material, the proportion of open pores in the porous silicon carbide sintered body can be increased from 18 to 18% by volume.
It can be adjusted within a range of 70%. If the particle size of the SiC particles is about the same, the strength of the porous body tends to decrease as the ratio of open pores increases.

On the other hand, if the open porosity is the same, the smaller the particle diameter, the higher the strength of the porous body. Therefore, a composite material for a pump having desired strength and wear resistance can be obtained by appropriately adjusting the ratio of open pores according to the properties of SiC, which is the starting material, by the method described above.

In the case of common pump materials, the open porosity is 50 to 7.
A porous silicon carbide sintered body with a coefficient of about 0 may be used, but
As a composite material for a pump component used in an environment of severe wear, a porous silicon carbide sintered body with an open porosity of 18 to 50 inches should be used to perform the composite described below.

That is, in the present invention, the open pores of the porous silicon carbide sintered body obtained as described above are impregnated with either an epoxy resin or a polyimide resin and solidified. This makes it possible to impart excellent strength and wear resistance to both acidic and alkaline liquids.

Impregnation with the resin is performed as follows.

That is, the resin is degassed under vacuum at room temperature, and the porous silicon carbide sintered body is also degassed under vacuum to impregnate the resin into its open pores. Any of the resins can be impregnated into the open pores at room temperature, and the open pores within a range of 3 to 5 mm from the surface of the porous silicon carbide sintered body are reliably filled.

Epoxy resins and polyimide resins can be cured by applying all the heat, and the resin shrinks little during curing. Therefore, the three-dimensional network structure of the porous silicon carbide sintered body is not destroyed.

[Embodiments of the invention]

Next, the present invention will be explained with reference to examples.

Containing 94.6% by weight of β-type SiC crystals, the remainder substantially consisting of 2H-type crystals, and containing free carbon, oxygen, iron, and aluminum in amounts of 0.3% by weight or less, average particle size Q, Using 28 μm silicon carbide powder, 5 parts by weight of polyvinyl alcohol and 300 parts by weight of water were blended with 100 parts by weight of this silicon carbide powder and mixed well.
It was then dried.

From the thus obtained dried product, a cylindrical test molded piece 1 having a length of 40+m++ as shown in FIG. 2 was prepared by press molding using a mold.

The tip 2 of the test molded piece 1 is hemispherical and has a diameter of 12 mm, and only the lomm of the tail 3 has a diameter of 8++.
It has become a. The density of the test molded piece 1 is z, otl
It was crd. This test molded piece 1 was placed in a graphite crucible and fired in an argon atmosphere at a maximum temperature of 2000° C. for 10 minutes to prepare a test sintered piece.

The density of the obtained test sintered piece was 2.05t/crtl
So, the open porosity is 35 volume =! II) It had a three-dimensional network structure in which plate-like crystals of silicon carbide were entangled in multiple directions, and its shrinkage rate was 0.3% or less.

The open porosity of the sintered piece with such a three-dimensional network structure can be changed by adjusting the addition rate of polyvinyl alcohol, the press pressure when preparing the molded piece, the temperature increase rate during firing, etc. Ta. In this way, the open porosity is 55%
A test sintered piece consisting of a 36% porous SiC sintered body was prepared.

Next, the sintered test piece is impregnated with either an epoxy resin or a polyimide resin in a vacuum at room temperature, and assimilated by raising the temperature, thus forming the test piece NCkl of the present invention.
~5 was prepared. As the polyimide resin, "Chemitai" CT 43 oJ manufactured by Toshiba Chemical Corporation was used, and as the one-component epoxy resin, Shin-Etsu Silicone Co., Ltd. As the liquid epoxy resin, Epoxy 2706 J manufactured by Shin-Etsu Silicone Co., Ltd. was used.

On the other hand, for comparison, SiC of the shape shown in FIG.
Test pieces 1 to 3 are made of a dense sintered body, an M2O3 dense sintered body, and high chromium cast iron, and test pieces 4 and 3 are made of a porous SiC sintered body that is not impregnated with epoxy resin and polyimide resin. Example 5 was prepared.

Such test pieces 1 to 5 of the present invention and comparative test piece N [
A wear test was conducted on each of Ll-5 as follows. That is, the tail end of each of the present invention test piece and the comparative test piece was fixed to the outer periphery of a disk with a diameter of 140 mm, and diluted sulfuric acid containing 2% by weight of No. 8 silica sand was added to the slurry solution (3). In a slurry liquid adjusted to pH 9.8 with N and OH,
The disk was rotated at room temperature for 5 hours at a speed of 15 m/sec at the outer periphery, and the wear condition of each of the present test piece and comparative test piece was examined. Table 2 shows the abrasion test results of the present invention test piece N11l~5 and the comparative test piece Nal~5.

Table 2 Figure 1 (A) is an electron micrograph showing the metal structure of a porous SiC sintered body with an open porosity of 55 volume, and Figure 1 (B) is a porous SiC sintered body with an open porosity of 36 volume. It is an electron micrograph showing the metal structure of a solid body.

As is clear from Table 2, the present invention test pieces Nal~5, the comparative test pieces N114 and 5 not impregnated with resin.
Compared to the above, it had the same excellent wear resistance in both alkaline and acidic slurry liquids.

〔Effect of the invention〕

As mentioned above, the composite material for pumps of the present invention is made of silicon carbide as a base material and is impregnated and solidified with epoxy resin or polyimide resin, so it has the following excellent effects. .

(1) Stable wear resistance against both acidic and alkaline fluids, durability against seawater and fluids containing chlorine ions, and impact resistance. Are better.

(2) Pump parts manufactured with this material:
It is lighter and easier to handle than conventional cast iron pump parts.

(3) Since the shrinkage rate during the sintering process is extremely low at about 0.3% or less, precise products with high dimensional accuracy can be obtained.

(4) Ceramics alone are extremely brittle;
Precise machining is difficult in practice, but since the material of the present invention is a composite of the above-mentioned resins, it can be easily machined in the same way as conventional cast products.

(5) A pump cannot exist on its own; it is installed together with piping, pulp, tanks, and other various equipment. Therefore, the pump must have strength commensurate with the materials used to form these various parts.According to the material of the present invention, the ratio of open pores in the porous silicon carbide sintered body can be changed. By doing so, the desired strength can be easily obtained.

(6) Even when manufacturing pump parts with various strengths, the manufacturing process is the same, so what is the manufacturing process?
It can be simplified.

(7) When manufacturing parts with complex shapes such as pump impellers and casings, the products are free from defects such as cavities and cracks that occur when manufacturing them using conventional casting. Since the thickness only gradually decreases with use, it becomes possible to predict the lifespan and improve its reliability.

(8) Compared to conventional plastics made by dispersion-strengthening SiC needle crystals, the degree of dispersion is extremely uniform, making it suitable for manufacturing rotating bodies such as pump impellers.

As described above, the composite material for pumps of the present invention provides numerous industrially excellent effects.

[Brief explanation of drawings]

FIGS. 1A and 1B are electron micrographs showing the metal structure of the porous silicon carbide sintered body used in the present invention, and FIG. 2 is a side view of the test piece. In the drawings, 1...test piece, 2...tip part, 3...tail part. Figure 1 (A) Figure 1 (8,)

Claims (3)

[Claims] (1) For a pump comprising a porous silicon carbide sintered body having open pores with a three-dimensional network structure, the open pores of which are impregnated and solidified with either an epoxy resin or a polyimide resin. Composite material. (2) The composite material for a pump according to claim (1), wherein the porous silicon carbide sintered body is made of silicon carbide containing β-SiC as a main component. (3) The composite material for a pump according to claim (1), wherein the proportion of open pores in the porous silicon carbide sintered body is 18 to 70% by volume.