JPS605828A - Filter of ceramic foam body and molten metal filtration - 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 Porous ceramic foam materials are already known in the art and have been described, for example, in U.S. Pat. Are listed. Also, U.S. Pat. No. 3,893, issued July 8, 1975.
Molten metal, particularly bath molten aluminum, is actually the final cast gold A. It generally contains the same 1T4 solids that are harmful to TS4 products. The entrained isomorphs of clay appear as inclusions in the final manufactured product after solidification of the molten gold envelope, reducing the ductility of the final product or deteriorating the final gloss and anodizing properties. There are several possible causes for the inclusion of such inclusions. for example,
These inclusions may be fragmented surface oxide films that are entrained throughout the final bath melt. Besides that,
Inclusions may enter as insoluble impurities such as carbides, oxides, etc., and also in eroded furnace and chimney refractories.

Naturally, it is desirable for non-accommodations to use molten aluminum, especially if the resulting metal is aluminum alloy 52.
Removes entrained solids from the final cast product or minimizes it when used in decorative products such as decorative trim or sheets made from aluminum alloys such as 5000 aluminum alloys such as 52 and 5657. The goal is to create an improved filter that can be used to reduce the amount of water used.

Other aluminum alloys that would benefit from improved filtration include aluminum alloys such as aluminum alloys 1145 and 1188 to reduce pinhole defects in thin products and maximize productivity during rolling. Aluminum condenser foil made from alloys, extrusion alloys such as aluminum alloy 2024 and 7075 for high quality against ultrasonic waves, and 6000 units such as aluminum alloy 6061 for higher productivity in extrusion operations. There are extruded aluminum alloys, etc.

The above-mentioned inclusions deteriorate the properties of the finally assimilated alloy, and cause a decrease in processing efficiency and properties of the final product. For example, aluminum alloy 5252
One type of finish blemish that is also particularly important to decorative trim or sheets made from gas flux
Although intense melt processing methods such as ng) provide the lowest incidence of these defects, they have not been successful in reducing the defects to an extent satisfactory for marginal applications. Conventionally, filtration of the melt has been used to reduce such defects caused by the presence of inclusions in the melt. The most common form of melt filtration involves a screen of coarsely woven glass cloth placed within the transfer and injection tubes or within the molten metal reservoir on top of the solidifying ingot. It has been found that such filters are only partially effective since they only remove large inclusions.

Another type of filter that is widely used is a bed filter, for example made of plated alumina.

Such filters have a number of drawbacks, perhaps the most important of which is that it is extremely difficult to control and maintain a pore size sufficient for effective filtration. Another problem with such filters is that they tend to produce initially poor quality metal at the beginning of each casting operation.

This phenomenon is caused by the so-called ``putting effect'' (bucking effect) of the ingot.
t, t + effect), resulting in an ingot with a relatively poor quality padding that must be scrapped and red-treated. must remain molten even when not in use.

In comparison, porous ceramic filters appear to be less desirable. However, the successful use of such filters for demanding functions such as filtration of molten metals requires that the filters have certain physical and chemical properties. In particular, 5Jf3 foam ceramic bodies require a certain throughput rate and uniform structure to efficiently filter molten metal at commercially acceptable rates and purity. As a corollary, foam materials must be able to withstand chemical attack by molten metal to facilitate their widespread use as filters.

To date, various methods have been proposed in the art for producing foamed ceramic foam materials. In particular, ball CBa1
U.S. Patent No. 6,111,396 by Mr.
A method has been proposed in which a nearly foamed organic polymer impregnated with a cutting material is compacted by passing it through preconditioned rollers to remove excess refractory material. This method, which is comparable to conventional removal methods for various citrons used in the art, has an inherent drawback in that the slurry is completely uniformly distributed throughout the object. That is, the outer 111u portion of the object tends to be plated with slurry thinner than the area near the center line.
This type of defect is caused by the t
l'f+' has 1. Objects with large and therefore high transmittances are likely to have weak and undesirable surfaces and edges5, whereas objects with relatively low transmittances tend to have undesirable central occlusions. It's a clear win.

#iBoth of the major deficiencies make the J foam unsuitable for use in filtration of molten metals.

The main object of the invention is that the plate has a fairly high temperature resistance, can be used with various Class A molten metals, and is suitable for heavy use associated with filtration of molten metals. 1j to have a structure that can withstand deterioration under conditions
The purpose is to create a filter made of ceramic foam.

Yet another object of the present invention is to provide a ceramic original filter as described above with a cylindrical portion, which is characterized by ease of manufacture and reasonable cost.

Yet another object of the invention is to overlook the above-mentioned technical deficiencies,
Contaminate the bath melt and the final gold PAJJ! 1. Decrease the desirable properties of the product. It is an object of the present invention to provide a filter made of a thermoplastic foam such as CimaeBb.

Other objects and interests of the invention will become apparent upon careful consideration of the following description.

It has been found that according to the present invention, the above-mentioned objects and point 1j are easily achieved.

The present invention provides a highly efficient ceramic foam filter for use in filtering molten metal, particularly bath molten aluminum. The ceramic foam sidewall of the present invention is characterized by an open cell structure having a plurality of first interconnected voids surrounded by a web of the same ceramic material. The filter of the present invention is also characterized by its limiting t1j, gender combination. The same filter is Le UO~8
．． 000 x 10-7 cm". In addition, the filter of the present invention has an illusion permeability of 3.
The porosity, that is, the void fraction is equal to 0 to 0.95. In addition, the filter of the present invention is characterized by having 2 to 20 holes per linear cm, and a filter normal thickness of υ·10 to 100 rna. During the present invention, it has been found that the filter described above is particularly useful for filtering bath molten metal, especially molten aluminum. There are many advantages to using a filter like this one, some of which are mentioned above and will be discussed below.

Under normal conditions, 400-2500xl Q'cm2
air permeability of 0.8 tJ-U, porosity or void fraction of 95, and 8 to 1 B (i/r+
The comparative fine-tuned filter of the present invention having holes of
Used when filtering 5000 units of aluminum alloy [7, if the injected metal is particularly dirty, the hole size of 2 to 8 holes per linear α, 2500 to 8
11
It is better to filter out the golden nine with 1. This filtration can be accomplished by using a single ceramic foam filter of varying properties or a series of filters with varying porosity.

Therefore, in addition to the above, the present study also determined that the flow rate of molten metal through the filter was 1.25 to 1.25 per 1 dm" of filter area.
A method is provided for filtering molten gold through a ceramic foam filter having the characteristics described above, with a value of 12.5 dm3/min. According to another embodiment of the method of the present invention, the molten metal is prefiltered through a comparatively coarse ceramic foam filter of the present invention and then passed through a suitable comparatively fine filter of the present invention. Can be filtered. This prefiltration step may use a series of ceramic foam filters of decreasing porosity and is particularly useful for particularly dirty melts.

In accordance with the present invention, the ceramic foam filter described above has been found to be particularly useful for filtering bath melts, particularly molten aluminum. The ceramic foam filter of the present invention is made of cheap paulownia wood that is disposable and convenient to use.

As previously mentioned, the ceramic foam material of the present invention is characterized by a multi-interconnected open cell structure surrounded by a web of ceramic material. The characteristics of the filter of the present invention are that it is extremely effective in filtering bath metals, especially aluminum, at low cost, yet achieves high filtration rates with flexibility not previously available. It has been found that it gives a filter that can be used.

The combination of properties of the filter of the present invention is a critical condition for obtaining the desired results of the present invention. As mentioned above, the ceramic foam filter of the present invention has a 400 to 8000X
10~7a12 The preferred lifting platform is 400~2'
It has an air permeability in the range of 500 x 10"-7 Cm2. This air permeability is determined by forcing air through the ceramic power generating body at a measured flow rate.

According to this method, the pressure drop is determined by measuring the pressure difference between the air entering the foam and the air leaving the foam for a defined area and thickness of the foam. 4 The two-gas permeability is then determined according to the following equation:

where: - air permeability, μ = nitrogen illusion dynamic viscosity, Q = flow rate of air passing through, L - length, i.e., thickness of the ceramic filter material, A = area, i.e., defined area of the foam. , and ΔP=pressure base. According to the invention, 0.857In
A flow rate of 3/min and an area of 75 an2 were utilized. The method for determining the transmittance is the Bintman (Pit, man) method.
J. M. Daravalle's book Micromeretics, published in 1948 by J.M.
s), page 263. It will therefore be appreciated that air permeability is a function of many variables, including bulk density, pore size, surface area, and flow path tortuosity. Honda 6 Akira Jl is 2500x1[]'c
Transmittances greater than n+'' give inadequate filtration unless the bath molten metal is particularly dirty, in which case B o o o x 1o-7Crn2
Transmittances up to 100% can be used. Also 4 [30
It has been shown that transmittances smaller than 0-76+++" will result in seedlings with undesirably large 1.c heads. A particularly preferred range of transmittances is between 1'00 and 15".
It has been found that within this range optimal filtration is obtained and the resulting head build-up is small.

In addition to the above, the ceramic filter of the present invention has a
It should have a porosity or void fraction of from 0.95 to 0.95. This variable defines the amount of porosity or voids within the ceramic body and can be determined according to the following equation:

where f - total porosity or void fraction, d - density of the ceramic body, and db = bulk density of the ceramic envelope body. This formula was created by John Riley.
Wiley) published in 1960.

Kingery)'s book 1 Introduction to Ceramics (I)
ntlrOduction to Ceramics
)” can be found in ]41.6 jl.1(
-7iL4 results are shown to be obtained with porosity values from 0.85 to 0.90. Of course, the dimensionally constant value for dT will depend on the q+1 constant ceramic object. For example, for ceramics based on alumina-chromia, the porosity value is 0.6.
It corresponds to a bulk density of 5-0.2 b g/Cm3, and the optimum value corresponds to 0.65-0.45 El/Cnl3. As mentioned above, the comparison filter with a coarse predetermined pitch is 0.90.
It should have a porosity of ~0.95.

In addition to the above, the ceramic filter of the present invention has straight gland 1c+
The effective pore size range, i.e. the pore density, expressed in number of pores per ++, is 2 to 20 pores per linear αL, preferably 8 to 18 pores per linear cm, and optimally 1 linear cm.
There should be 10-14 holes per hole.

The above six variables, namely permeability, porosity and pore size, are critical prerequisites for obtaining the significantly improved properties of the present invention. That is, these variables are i+ of the filter of the present invention.
4; < Mutual influence in achieving power efficiency. These variables determine how many holes there are in the filter, how interconnected the holes are, and what size they have. can be,
In addition, depending on the surface area of the ceramic web and other variables, it is possible to use a thicker or more efficient ceramic foam filter.
It should have an effective filter thickness, ie, thickness in the direction of metal flow, in the range of 100 mm. The optimal thickness of the filter is 65
~65 man. Filters with thicknesses thinner than 10 mm are not effective in removing most of the non-metallic material from molten metal, and thicker than 100 mm, the most effective range of filters is anyway between 25 and 35 mm thick. This has been found to be disadvantageous as it reduces filtration speed.

Yet another characteristic of the effective filter of the present invention is that the filter has substantial structural uniformity. In order to provide an effective filter for molten metal at t2, the ceramic foam must be highly uniform in structure. Therefore, while a certain percentage of plugged pores is useful and desirable because they increase the tortuosity of the flow path, these plugged locations are not clustered together but are evenly distributed throughout the ceramic body. It's good to be there. If the open base points are clustered, it will only cause a % drift phenomenon and a decrease in filtration efficiency.

A variety of materials may be used to fabricate the expanded ceramic foam filters of the present invention. An advantage of the present invention is that the filter of the present invention is cheap and easy to manufacture, making it a convenient and disposable filter.

The main component of the ceramic polymer material of the present invention is from 40% to 95%, preferably from 45% to 55%.
is Al2O3. Al2O3 is particularly desirable for use as a ceramic tuna filter because it is not attacked by, for example, F8 fused aluminum or tfP,
However, silica is the first to be attacked by all those bath melts.

Moreover, alumina has a suitable strength to withstand chemical attack, and has mechanical strength and mechanical bending ability that can withstand extremely high temperature training. are doing. [mentioned above]1, the ceramic material of the present invention also has a
Up to 500 Cr2O3, preferably 10 to 1700 Cr
Even if you put 2O3 into 1, it won't be the 1st f.

This component is extremely important because it has been shown to provide very good thermal resistance, ie, resistance to erosion by molten currency notes at high temperatures. Historically, ceramic foam laterals have also been made with (1,1-12% kaolin and (
f, taha) with bentonite? It also contains a thermal Frt product with 2.5 to 25% of a hardening agent, preferably aluminum phosphate, which substantially reacts with the gold parent.

According to the present invention, the above-mentioned aspects and advantages are achieved as follows: 1-1
An open cellular foamed organic polymeric material having a predetermined permeability and elasticity is prepared and impregnated with an aqueous slurry of a chicken trobiic ceramic composition to a maximum of 1 hour while applying a shear force K41 impregnating said polymeric material in an amount sufficient to achieve the desired effect, and passing said material at least twice through preconditioned rollers, the first time to a range of about 50 to 90% of the thickness of said material. The transmittance and the transmittance were also controlled by a method consisting of removing excess slurry from the material by temporarily compressing it within the range of 70 to 90 degrees within the body and a second time. The method for producing a ceramic blasting body having a 1'+ uniformity can be easily retarded. After impregnation and excess slurry removal is complete, the resulting foam material is heated to remove organic foam components. Items that cannot be obtained may be used as is, but
Further heating may be applied to sinter the ceramic material if desired.

In accordance with the present invention, it has been found that the air permeability of the resulting ceramic object depends on the permeability of the foamed organic polymer used in its manufacture. For example, about 800
Ceramic RCT body with transmittance in the range of ~2.200 x 10-7
It has an air permeability of 10@-7 cm@2 and is made from an encapsulated polyurethane phase. Furthermore, if the transmittance of the fcs raw material foam material is selected within the range of ±2%, ±
5. The production of ceramic foams with a predetermined transmittance within % is facilitated.

In addition to transmittance control, the ceramic foam of the present invention also provides
It must have structural uniformity and a specific range of void cell sizes. The uniformity of Pakunzukuri is foamed fm lj &
There is a relationship between the elasticity of the IC combined material 1/l= and 1 force.11
1 It's clear. In addition, force resistance can be determined according to the standard set forth in ASTM-D-1b67-71 for the properties of elasticity as measured by pressure I@residual strain and ball bounce. The compressive residual strain determined by the compressive load deflection test is the compressive residual strain of the foam, e.g.
It indicates the extent to which a material returns to its initial size or thickness after being compressed to a specified reduction such as J]. Foams found to be suitable according to the present invention have been compressed by 50% to 60%
% and thus the bales return to at least 70% of their initial smoothness after removal of the pressure) ψr. S+P strength determined by ball rebound test The resistance of the old material to compression was measured by the height at which a ball dropped from a determined distance onto the foam sample rebounded. It is something. If we pay attention to the rate of return of the ball to the initial height, we can see that the present invention has an excess of 1. c-foam has been found to be a material that provides greater than 25% ball bounce.

Although the above properties are measured by tests conducted under dry conditions, such properties are substantially maintained in an aqueous environment, such as during impregnation with the aqueous ceramic slurry of the present invention. Must be number one. Therefore, it has been found that hydrophobic foam materials work better and are preferred over hydrophobic foams, as they lose a significant amount of elasticity in the aqueous environment. It appears that defects occur.

In view of the above-mentioned criteria, the foamed organic polymer 1 composite material that can be employed in the production of the foam of the present invention is a polymerized iso7anate in the composition of Soneso A1. Polyester and polyether polyurethanes such as ``elastic'' or ``low-temperature cure'' urethane paulownia; foamed polyvinyl such as polyvinyl chloride, polyvinyl acetate, and foamed polyvinyl of various copolymers; polyethylene or polysiloxane subpolymers and copolymer There are excellent high modulus reticulated hydrophobic materials such as G-4 coated polyurethane; and extruded materials made from suitable natural resins such as cellulose resin. The foam material must burn out or volatilize at a temperature lower than the firing temperature of the ceramic material with which it is impregnated. As mentioned above, the dimensions of the foamed paulownia material are n[
It should correspond approximately to the dimensions of the desired ceramic object. Thus, a foamed paulownia material having a thickness, for example in the range of about 10 to 100 mnl, is used when the resulting ceramic foam is to function as a molten metal filter.

The polymer material coated on top has both properties of permeability and uniformity, as well as the properties of bath melt metal filters! To be effective in radius construction, a burr must not have a hole size within specified limits. It has been found that the size of the pores or voids 11iIJ is important for making the structure of the ceramic body uniform and should vary within the range of 2 to 20 pores per linear crn (1ω). The control of the variables listed above contributes to the structural uniformity and permeability of the finished filter, and to the reduction of flow velocity and effectiveness through tortuous flow passages. do.

Although these factors are military costs, the following discusses additional factors that should be considered together to achieve the final ceramic foam product.

The organic foam ladle selected with respect to the above description is then impregnated with a slurry of chicken trobiic ceramic material. Trobiy properties are critical to the present invention because they affect the structural uniformity and strength of the final ceramic foam product. The thixotropic monthly charge is tr under low rate shear conditions.
It is a material that exhibits a high resistance to flow and a correspondingly low resistance to flow under conditions of relatively high rates of shear.

Kneading is relevant to the method of the invention, in which the ceramic slurry rapidly enters and fills the voids of the organic foam 1, thereby creating a flow sufficient to cover the surrounding <711 coalesced web. At the same time, it must have sufficient viscosity to resist flowing out or dripping from the packaging material once impregnation is complete.

It has been discovered by the present invention that certain ceramic paulownia wood produced in combination with a specific air hardener and temporary binder: (1) exhibits desirable thixotropic properties; This means that impregnation can proceed successfully.

The ceramic slurry used for this fitting does not exceed 4M depending on the final use of the foam, so it can be used in a variety of fire-resistant applications. For example, ceramic materials can be used. In particular, phase 1 such as mixtures of alumina, chromia, zirconia, magnesia, titania, silica and the like may be present.

This type of soap is noteworthy because it can be used under relatively high heat conditions, that is, under high humidity conditions. However, mullite, calcined clay and high softening temperature 17! Other materials with low fire resistance, such as glass, can also be used, alone or in combination, with fire-extinguishing materials, for example at up to 15%, to produce foam products. Ranel products are used as bath melting all-pole filters δ The first lifting platform is made of certain ceramic materials! Must choose 9.7. The only condition is that the material chosen provides sufficient resistance to chemical attack of the bath metal during the entire time it is exposed to the bath metal during filtration. That's what it means. The composition of pith that has been successfully employed in this application consists of a mixture of alumina and chromia.

The compositions also carry a room temperature binder or a curing agent that imparts a green 94Il& to the slurry, particularly during firing and optional sintering processes where the foam is subjected to thermal stress.

In preparing the foam of the present invention, from 2.5% to 25% of a curing agent that does not substantially react with the molten metal is used.

Air-hardening agents or fc binders require force or heat;
Preferably by drying, usually chemically.

Although the ceramic slurry is hardened by reaction, it may be hardened by heating to a mild temperature. Preferable 1,
The air-hardening agent is 77j-aluminum in the form of a 50% water bath solution. Other air hardening agents that can be added include, for example, magnesium orthoborate, aluminum hydroxychloride, and the like. At least one alkali metal silicate such as sodium silicate is used. Although it is not used even in the first place, it is common at a temperature of about 815.56℃ (150 [J'F)?
WI! LAs a result, the groove hardening will be worse, so please do not
l and others are not very desirable. In addition, they contain primarily silicon, and possibly sodium as well, which is commonly understood as a bath melting agent. Similarly, ethyl silicate and other phosphates may be used, but are less preferred. Positive'l
+T&aluminum is preferred because of its unusually favorable combination of nonreactivity, stability over a wide temperature range, and good hardenability.

As mentioned above, the σ2-enhancing agent is preferably added as an aqueous suspension, containing equal proportions of binder and water in the case of aluminum orthophosphate. The bonding agent provides green strength prior to forming the ceramic bond, ie, after burnout or volatilization of the flexible foamed paulownia web. The binder 4'A material provides sufficient strength to hold the mixture together to form the final product. In fact, the stability and strength of the chemical bond imparted by the preferred hardening agent allows the product to be handled at this point without high temperature sintering for many applications. is sufficient. This strong absorption is substantially large and exists over a wide temperature range. 12% in the second preferred example
Orthophosphorus plate aluminum with a content of up to 17% is used.

In addition to the binders described above, certain substances, herein referred to as rheological agents, are used which serve to increase the desired trobiness of the slurry. Several materials are known that can serve as flow agents, including certain organic materials such as carboxymethyl cellulose and hydroxyethyl cellulose, and certain inorganic materials such as bentonite and kaolin. Among the materials available for use in A1 in this regard, bentonite has been found to be particularly preferred. Bentonite is a naturally occurring clay consisting primarily of aluminum and silicates, usually containing magnesium and iron. Be/tonite not only reduces the thixotropic properties of the slurry, but also produces a certain glassy phase when the article is fired, increasing the strength of the final envelope. In addition to bentonite, Shochi's kaolin can also be used, and this kaolin has the same properties as bentonite. Kaolin is a clay consisting primarily of alumina and silica.Of course, to approximate the first composition, chemical dispersion of said materials is used. Typical overflow limits range from about 1.1% to about 12% of the slurry. In a preferred seventh embodiment, the fluidizing agent is about 0.5% to about 5% of the slurry. It is added at hl within the wholesaler l!1.

As mentioned above, chicken trobiic ceramic particles can be prepared in various compositions, but approximately 40-80%;
Preferably an I'i of 45 to 50 %, up to about 20%, preferably in the range of about 10 to 15%, up to about 10%, preferably about 2 to 5
% fit of kaolin, about 0.1 to 10 So, preferably (2), and turtle bentonite within the range of about 0.5 to 2 So, and about 5 to 50%, preferably about 25 to 35 It has been determined that a particular λ composition consisting of aluminum acid (50% bath solution) is extremely effective at colloidal solids within the range of As is well known, for the purpose of adjusting the viscosity, up to about 20% water can be added to the slurry in an amount of about 5 to 10 centimeters. 1 U to 40% of water is present.Although the above composition is not indicated within the preferred range, the present invention is not limited thereto, and other compositions may be prepared by subtracting from the above-mentioned ingredients. It doesn't work either.

In addition to its thixotropic properties, ceramic ceramics must have carefully controlled viscosity during and during impregnation. The viscous feature has been shown to have a substantial effect on obtaining reproducibly uniform ceramic products. The desired range of viscosity is 1X1tJ"~
80X'103 centipoise, preferably 10X1
0” to 4 Q x I Q” centipoise (Cps
) is 21'lJ clear. The viscosity is 1181 during the formation of the slurry, and the pressure must be within the range before the slurry is impregnated into the foamed organic Mf body. As mentioned above, the most convenient method for controlling and controlling the viscosity is to reduce the excess water content J1f within the range specified above. The viscosity was determined using a six-channel spindle on a 13 rookfield I (VT Viscometer) after the slurry had been mixed for 50 minutes at 60 revolutions per minute in a 76 liter (80 quart) Hobert I mixer. The temperature was measured at 25°C after 20 minutes of rotation at 20 revolutions per minute.

Take a scoop of ceramin slurry and prepare it to a consistency within the above-mentioned limit.
Impregnation of organic abrasions can be carried out, i.e., a plate of foamed polyurethane in a network structure with a pore size of 2 to 20 holes per linear cm is impregnated with the slurry, and finally the same Ensure that the voids in the foam are completely saturated with the same slurry.Impregnation can be done in a number of ways, for example by completely immersing the foam board in the slurry;
Similarly, air is expelled from the pores of the same plate by squeezing through a pair of rolls immersed therein, so that as it exits the rolls, the expanded foam sucks in the slurry, thereby filling it with slurry. Ru. Another method that can be employed is to place the foam in a slurry bath in a closed container, ``evacuate the container to create a vacuum, and immerse the foam in the slurry bath; This method includes the steps of releasing the vacuum inside the container. This method, which is a modification of the vacuum impregnation method, also results in complete saturation of the foam with slurry. Of course, simply apply a vacuum force to one side of the foam;
Other impregnation methods may be used here, including standard vacuum impregnation methods in which the slurry is sucked through the opposite side in between.

The preferred infiltration method employed involves completely immersing the foam in a slurry bath and repeatedly compressing and expanding the foam with a mechanical Zosinja device made from perforated steel plate. This step is carried out for 60 seconds to 1 minute, or, of course, until the voids in the foam are completely saturated. In view of the previously mentioned chicken trobi nature of the slurry, a particularly advantageous and important step is to apply a continuous shear force during impregnation to maintain the desired flow rate of the slurry into the foam. . This step 1 can be achieved by means of miracles such as continuous high speed stirring of the slurry. The method employed in the present invention involves constantly vibrating the slurry during impregnation. In this regard, it should be noted that all of the previously described impregnation methods require that the slurry be maintained in a highly fluid state by means of a shearing action such as vibration. Once the foam has been impregnated, the shearing action is discontinued. The slurry within the foam becomes obstructed by flow J1 and is substantially completely retained within, with little loss due to dripping during subsequent impregnation (transport from the lift station) of the foam.

Once impregnation of the foam with the slurry is complete, the impregnated foam material is then processed to remove excess slurry from the material. This removal or expulsion of excess slurry must be precisely controlled and uniform throughout the foam body in order to produce a uniform ceramic product. As mentioned above, various methods are known in the art for removing slurry from impregnated organic foams, including squeezing, blowing with compressed air, centrifugation, passing between rolls, etc. The method does not give satisfactory results in this respect. In general, platforms using roll-to-roll passes are susceptible to centerline blockage or ceramic material remaining after expulsion because the resulting product has excess slurry remaining and congealing in its core. If the product is mechanically poor or weak or has any defects, pass the impregnated foam paulownia wood between the pre-adjusted rollers at least twice, the first time being The thickness of the material is approximately 50-9
The expulsion is advantageously carried out by a process consisting of squeezing to within 0% and squeezing to within 70-90% in the next pass, resulting in a uniform foamed ceramic product. It turns out that it can be obtained. Thus, multiple rolls with the same reduction or increasing reductions can be processed to produce a ceramic article with increased strength 7 and no centerline blockage. Furthermore, multiple rolling treatments are required to prevent the final product from being rolled, which is a limiting condition for bamboo VC when the final ceramic product is made for use as a bath melt filter. 2
The error rate can be controlled to >MS.

The characteristic feature of the expulsion method is that the rolling process takes advantage of the turbidity of the slurry. That is, the slurry flows freely under high shear forces, but the shear force Given that one pass is virtually a stationary wrinkle L, tighter control over slurry removal is obtained by 174 μIJ of roll gap (reduction rate), roll speed, and/or roll diameter.

Adjustments to the roll gap and roll speed, in particular, can determine the shear curvature that the slurry undergoes and, therefore, the degree of slurry removal and the shape of the slurry that is redistributed into the rolling barb or web of foam.

The preferred rolling process utilizes a two-pass process, although multiple passes may be desirable for applications where the foam is thicker than 5 cm. As mentioned in a, the reduction rate determined by the two-pass process is 50-9L1% in the first pass, and 70-90 in the next pass.
%. The preferred reduction rate within the DU book 1α range is 70 to 80 Chu for the first round, and 70 to 9 Chu for the second round.
It is 0%.

Evacuation can be carried out using an American roll stand apparatus having two cooperating rolls.

With the spear 1, the foam material is first passed through the roll stand and then recirculated for a second pass.

If the second pass is to be carried out at a different reduction rate, the pair of roll stands should be spaced apart to allow successive passes of the packaged material at different reduction rates. It is appropriate to install the Other modifications that are not considered within the scope of the present invention for sequentially setting the roll fii
'l This method involves only one pass through a roll forming machine having six rolls that establish a continuous roll gap. This method offers the advantage of using only one roll stand and carrying out two threading steps in -1 operation.

In addition to the roll stand described above, the rolls used in the stand are also equipped with gratings (gr. Advantageously, it is coated with a material such as tt) or the like. Another feature of the equipment used for slurry evacuation is that it includes a movable delivery table located at the exit of the roll stand for supporting and transporting the newly rolled foam as soon as it exits the roll stand. be. In summary, if covered rolls and O/movable delivery tables are used, they will reduce undesirable deformation effects and minimize unnecessary handling of the foam article that can disrupt slurry distribution. Therefore, the P-ru type is useful for improving the integrity, groove uniformity, and shape of the product.

As previously mentioned, the multiple rolling process surprisingly increases the transmittance of the final ceramic foam product as an advantage of the process. That is, if the material is passed through the roll twice at the same reduction rate,
The transmittance of the final product increases by 60-5 J%. This increase is due to the roll passing process making the slurry distribution more uniform than would have been obtained by a single roll pass reduction of %Ji + It can be seen that it is a claw and fang. Furthermore, a second or subsequent roll process in which the first roll process is rolled at a higher reduction rate than the first roll process has a higher permeability than the single roll process. It gives results that increase by more than 100%.

After the removal of excess slurry is complete, the resulting foam material can be dried and, if desired, fired to form a bath-fused ceramic foam product. This drying step is primarily used to remove the foamed organic polymer from the product. Generally, conventional drying methods can be used at this point, but the heating rate suitable for removing the foam must take into account the heat provided by oxidation of the foam itself. should be kept in mind. The effect of this phenomenon is especially noticeable when heating large volumes of foam, if a significant volume of the heating chamber is occupied by the product. In such cases, the ceramic filament should be maintained at a temperature in the range of 2QO to 570''C to avoid excessive heat generated by the chemical reaction, which may break under the stress of ζ(1). The exact temperature will depend on the foamed organic material used and therefore need not be discussed further here.

As mentioned above, the ceramic foam may be further heat treated or fired to melt the ceramic particles into a highly refractory f111 structure, if present. As already mentioned,
This step is an optional step. For example, if the foam product of the present invention is used as a filter for molten aluminum, it is only necessary to heat treat the foam material at temperatures between 540°C and 600°C to remove the Ij' 43A component. This is because the mouth is known. The resulting article is therefore aluminum 1 which melts at a high temperature of 760°C.
It is suitable for use in a single alloy. In such cases, the hardening agent or binder will impart the necessary strength to the product and a full sintering process will therefore not be necessary.

If the method described above is used, the thickness will be 6 to 100 mm.
Ceramic foams can be produced with an area of up to about 1 m2 or more within the range of 7 J). Depending on the foam material used, the origin i' is directly ij'; J! Approximately 2 to 2 per I Cnl
Number of pores up to 0 and about 100X 10-7m2 to 1
Transmittance inside the medium IL recess at 0+000
It will have a high degree of bulkiness at jrr3"2.

Invention α] When the foam product is used as a filter for molten metal, the air permeability is approximately 400 x 10'a
In the range from n2 to 8000 can be varied to suit the specific conditions of the product's end use.Thus, for example, 40
It is possible to make a relatively fine filter with a transmittance of 0 to 2500X 10-7an2 and a pore size of B to 181i' per cm. Such a product would be useful for filtering 5000 units of aluminum alloy. However, when filtering the molten gold J'i, if the input gold D4 is particularly dirty, the molten gold J'i is filtered directly.
pore size from 2 to 8 per cm, and from 2500 to 80
The molten metal should be pre-filtered through a relatively coarse ceramic foam filter with a permeability in the range of 0.00 x 10' cm2.

This preliminary filtration may not be interrupted by using a single filter with progressively varying properties or by using a series of filters of different porosity.

Accurate control of the transmittance of the resulting ceramic foam product is possible. Furthermore, the ceramic foam of the present invention exhibits structural uniformity without centerline occlusions or weak outer surfaces. When the product of the present invention is used for the filtration of molten Fa metal, the product can successfully withstand the harsh conditions long exposed to metal flow without blockage or rupture, and the resulting filtered metal is expected 1. It has been found to have significantly improved purity.

The resulting product is a bonded ceramic foam having an open cell structure characterized by a number of interconnected voids surrounded by a web of ceramic, the ceramic foam having the structure defined above. It has characteristics. Gradual variation from coarse to fine throughout the thickness
If a single ceramic foam filter with C is desired, two or more sheets of polyurethane foam with appropriately different sized pores should be used! 111 may be used together. Of course, ceramic foam has certain melting properties; it
It may have any form desired based on the form required for the gold filtration process. /! 7J theory, although these forms can take many different forms, for the purpose of filtering molten aluminum, a particular form of filtering vessel in the conveyor between the furnace and the mold is preferred. There is. The flexibility afforded by the manufacturing methods utilized herein allows one to easily and conveniently make a suitable one. A particular advantage of the ceramic foam of the present invention is that the heptaramic foam has sufficient strength to withstand attack by molten metal and also advantageously oversizes the molten metal head to initiate the filtration process. There is no need to do so.

As explained above, the present invention also provides a method of filtering molten metal through a disposable ceramic filter;
As mentioned above, this method uses 1 filtration area for aluminum.
1.25-12.5 am3/min per dm2, preferably
It is characterized in that the molten metal is poured through the ceramic foam at a rate of 2.5 to 7.5 am3/min per 1'am2 of filtration area. Metal flow rates during typical aluminum casting processes range from a minimum of about 90 to 900 Kp per minute.
A typical metal flow rate is about 225 kilograms per minute, although it varies up to a maximum of more than 1000 yen. According to the present invention, E
DI ceramic materials are well suited for successful operation using high metal flow rates as described above. normally,
For aluminum, the specific flow rate of the metal in the filter should not exceed 35 min per 1'dm2 of filter cross section, preferably less than 21 to 17 min per 1-2 dm2. A higher flow rate through the filter will result in a filter that passes through the filter with a higher concentration of particles, which is undesirable for the production of grade sheet products.

The lower limit is determined by considering the collective size, but 45'0
Handling large metal flow rates in excess of 1 S/lJJ would require impractically large filters. +
A ceramic filter larger than 41J or 114 cm2, or i30drr,2 would be required. Therefore, a typical filter of the present invention has a capacity of 14 Kg per l di"
It can be defined as a specific flow rate of 225 mm/min (27 min of metal 2 passages) with a R1 of 40 cm21217 or 16 dm2.

In addition to the above, the quality of the input metal is important 1x, the inverse number. If the input metal is particularly dirty, then also [
If a relatively fine ceramic foam is used, which is also preferred, the same metal will readily become the fabric of the ceramic filter of the present invention.

The quality of production, that is, the quality of the metal that is filtered and processed, is the number of quality inputs. Therefore, a minimum input quality should be established to ensure good production quality. In order to ensure good production quality, according to the invention, the entire melt is prefiltered through a relatively coarse ceramic foam filter, and then a series of ceramic foams with progressively smaller porosity are passed through a relatively coarse ceramic foam filter. It is best to use a manufactured filter. Therefore, as already explained, according to the invention, the pre-filtration step typically involves 2 to 81 holes per 1 ann.
Hard hole size, 2500~8000X10-F(m”
air permeability, porosity or void fraction of 0.90 to 0.95, bulk density of 0.20 to 0.65, and bulk density of 10 to 100 +
A relatively open ceramic foam filter with a thickness of n111 will be used. A series of such filters with progressively lower transmittances are suitable for special applications.

Or again, the whole thing is gross (too early to be too high)
It is also possible to use a single prefilter or a single filter of the present invention, which has the property of changing from dense to dense (low air permeability).

The features of the present invention will be more easily understood with reference to the following examples.

Reference Example 1 Polyurethane foam having a thickness of 5 cm is prepared. 47%”203.13%0r203.3.
An aqueous ceramic slurry was prepared having the composition of 5% kaolin, 1% bentonite, and 14.5% colloidal aluminum phosphate added as an aqueous solution with an equal amount of water. The slurry contained 82% solids and 18% water.

The foam material was immersed in the slurry, kneaded to remove air, substantially filling the voids with the slurry, and then covered with the slurry, which was a fibrous web of foam material. The resulting impregnated foam material was removed from the slurry and about 80% of the slurry was squeezed out of the same feather by squeezing it through the impregnated foam material through a preconditioned roller. The foam material bounced back to its original size after passing through the rollers' and had fibrous polyurethane filaments coated with a substantially uniform residue of the ceramic slurry. The material was dried at 125°C for 1 hour and then at 0.5°C to remove water and volatilize and/or burn out the polyurethane fibers without crushing the ceramic and destroying the filament morphology of the ceramic. The mixture was gradually heated to 500° C. at a heating rate of 1/2 min. Foam material 500°
135C for 1 hour and then sintered together so that the ceramics sintered together thereby yielding an open cellular ceramic foam material having the shape of the initial foamed polyurethane bevels.
Heated to 0°C at a rate of 1°C/min and held at 1350°C for 5 hours. The properties of the resulting foam were as follows.

Transmittance 1425 x 10-7cm2 Porosity 0.8
7 Hole size Straight 13A 12 holes per ann Thickness
5 cnr Structural Uniformity Eroded Example 1 2.6% Magnesium, 0.04% Silicon, 0.05
A 22,500 Ky charge of aluminum alloy 5252 containing 1.5% iron and 0.06% copper was melted in a gas-fired open hearth and salt purple gas was added as a flux according to conventional methods. This still unfiltered metal was then cast into three rolling inits, each weighing 4,500 Kfs and having a cross section of 50 x 135 saws.

A second time, an alloy of the same composition was melted and prepared for casting according to the same method, but before casting the metal into a rolled ingot, it was placed in the ceramic foam filter made in Example 1, which was placed in the pouring funnel. i 4 Kg/dm2/
The difference was that it passed at a speed of 1 minute.

Only a 156n metal spatula was required to pass the metal through the filter. Also, during casting, after the metal of 3.500Kp is filtered through the same filter, the running head (ru
nning head) loss is 0.3 to 2.5 cf
Accumulated in n.

Qli upstream of the filter during 6Jj production of filtered gold IfA
Pressure filtration tests were performed on gold J'J4s taken from the downstream side and on gold bridges taken from the pouring pit during the casting of unfiltered metal. It was demonstrated that the filtration condition of the ceramic foam filter made of the foam of the present invention was excellent. The cross section of a pressure filtration disk made from unfiltered metal was compared to the cross section of a pressure filtration disk made from filtered metal.

These cross-sections show that the metal filtered by the ceramic foam filter of the present invention had almost no residue, whereas the pressure produced from the unfiltered gold The cross-section of the filter disc clearly showed the presence of a considerable amount of residue. Similarly, pressure filtration discs were made on samples from the upstream side of the ceramic foam filter, which revealed the presence of significant residue. This clearly demonstrates the effectiveness of the ceramic foam filter of the present invention.

The pressure filtration test described above was performed on molten aluminum from 9 to 11.
- This is a method in which a large number of non-metallic particles are placed in a 3 kg sample. During this test, molten aluminum is carefully pumped into a preheated 11-5Ky clay graphite crucible. 4) The bottom of the vase has a diameter of 30 mm.

A porous silica disk plug with a thickness of 311II11 is placed.

90% of the metal is forced through the disk by applying air pressure, and the remaining metal is allowed to solidify.

The disks and the contact metal are then sectioned, polished and examined by conventional metallurgical methods to reveal the Ll of the filtered non-metal.

Reference Example 2 The ingots made in Example 1 were all 0.75 tnm.
A sample of the thin plate was rolled to a thickness of
effects). It has been found that sheets made from filtered metals have about ten tenths of less linear defects than sheets made from unfiltered metals. The results are shown in Table 1 below.

This is strong evidence of the effectiveness of the ceramic foam filter of the present invention.

In addition to the above, the used ceramic foam filter used in Example 1 was examined metallographically. Considerable oxide streaks and non-metallic granules were found to be trapped in the web of the filter, providing further evidence of the filtration nature of the filter of the present invention.

Besides, the mechanical properties and composition of the metal filtered according to the invention were also tested. Good mechanical properties are obtained,
The resulting product was found to be free of metal contamination due to the use of the ceramic filter of the present invention.

Example 2 In addition, a 22.500 Kg melt of aluminum alloy 5252 was made in the same manner as in Example 2. In this case, the metal was filtered through a flat alumina bed in accordance with conventional methods for comparison purposes prior to being cast into rolled ingots.

The ingot thus cast was rolled into a thin plate having a thickness of 0-75+mm, and samples were taken from the ingot butt of the obtained fill, a position 50W from the ingot butt', and a position corresponding to the ingot head. These samples were then examined to determine the number of linear defects. The results of this test are shown in Table 1 below, along with similar data performed on the unfiltered metal of Example 2 and the ceramic foam filtered metal. This table 1fC1!
1. Results are expressed as percentages using unfiltered metal as a standard for comparison.

Table 1 Comparison of the number of linear defects Unfiltered gold H 100% 100% 100% bed filtered gold block 150% 25% 10% Metal filtered through a hexalamic foam filter 10% 10% 1o% These results clearly shows the poor quality of the butt portion of the ingot produced by filtration with a commercially available bed filter compared to that produced with the filter of the present invention.

Example 5 Additionally, a charge of 22,500 ni of aluminum alloy 525
2 was prepared in the same manner as in Example 1. The metal was passed through a ceramic foam filter made in Reference Example 1, which was placed in an injection tube similar to that described in Example 1. In this protected filter, the effective area of the filter is reduced by two-thirds, and as a result, the specific flow rate of the metal in the filter is 42 kg, which is higher than the specified maximum flow rate of the present invention.
Filtration f of Reference Example 1 except that /drn2/min:
It was the same as l'f.

All of the obtained ingots were rolled to a hardness of 0.75 w, and samples were taken and tested as in Example 2 to determine the occurrence of linear defects. The results of this test are shown in Table 1 below, and show that the unfiltered metal and the gold filtered through the ceramic foam at a flow rate of <14 Kr/am"/9" as in Example 1. These results are expressed in percentages using the unfiltered metal as the standard for comparison.-Through ceramic foam. The table below shows the quality of the product obtained in 3.

'1. (Example 4) Additionally, 22,500”g of aluminum alloy 52
52 was prepared in the same manner as in Example 1.

The filter was passed through a ceramic foam filtration fabricated according to Reference Example 1, which was installed in the injection tube in the same manner as described in Example 1. The uniformity was similar to that of the filter of Reference Example 1, but it was superior in the following points.

Transmittance 2140X 10'-7an2 pores = 1 cell 0
．． 92 Pore size 8 pores per 1 on In addition, this filtration @S0. ) The specific flow velocity of gold r3 is approximately 28 Kg/d
, m2/min. Therefore, this filter is 121! Although the metal properties and metal flow rate are within the scope of the present invention, the filter permeability, porosity, pore size, and metal flow rate are outside the preferred range.

All ingots made in this way are 0.750
After rolling to a thickness, samples were taken from the coil at positions corresponding to the head and butt of the ingot and tested in the same manner as described in Example 2 to determine the occurrence of linear defects. The results of this test are shown in Table 1 below, and are comparable to an equivalent test conducted on filtered metal, gold, and gold filtered through the preferred ceramic foam of Reference Example 1. The results have been compared. These results are expressed as percentages using unfiltered metal as the standard for comparison.

Unfiltered Metal 100% 100% Gold F filtered through ceramic foam ((12 pores/cm 10% 10%, filter - 14 Kf/dm2/m1n) Metal filtered through ceramic foam (12 pores/cm 10%) 8 pieces/cm 40% 60% filter - 28Kg/dm"7m1n) Therefore, the above example shows that if a filter within the broad specific range of the present invention is used,
It clearly shows that treatment according to the preferred conditions of the present invention results in a reduction in the occurrence of straight line defects by about 50%, as opposed to a 90% increase.

Reference example 6 5 cm thickness, 12 holes per linear meter and 4.60
A foamed polyester polyurethane paulownia wood having an air permeability of 0 x 10 = on2 was prepared. Aqueous ceramic containing 47% alumina, 16% chromia, 6.5% kaolin, 1% bentonite, and 29% aluminum orthophosphate (50% aqueous solution <= 14.5%, Y acid aluminum) Mixed for 1 hour at 5Q rpm in a 76t Hobart mixer. After mixing for half an hour, a sample was taken for viscosity testing. The slurry was shown to have a viscosity of 25.5 x 103 centipoise at 25°C as measured using a No. 6 spindle on a viscometer after testing for 20 minutes at 2 Orpm. A sample of the foam material was immersed in the slurry. , the same sample was subjected to about 60
It was compressed and expanded repeatedly for several seconds while the slurry bath was vibrated at 50 cycles per second to fill the voids with slurry. A sample of the foam material impregnated as in C was passed through a pre-gridded Q-roll to crush the thickness by 70% to remove excess slurry.

These rolls have a diameter of 76 mm and a diameter of 12.5 r.
pm O) speed. The sample substantially completely recovered its shape after completion of the roll.

The sample was then heated in an oven at 65°C for 1 hour and then at 95°C for 2 hours.
Dry for an hour. After drying, heat from 95°C to 260°C.
heating at 56°C/hour to 615°C, then 11°C/hour to 615°C, then 56°C/hour to 645°C, then to remove the polyurethane fibers without disrupting the ceramic web. This temperature was maintained for 4 hours. 260
A gentle heating from 'C to 615°C was necessary to prevent sudden temperature fluctuations resulting from oxidation of the polyurethane.

The resulting sample was fired in a furnace to 540°C using a heating rate of 56°C/hour, then to 1615°C using a heating rate of 2246C/hour, and then allowed to cool with the furnace.

The fired sample was found to be strong, with a peeled surface and p'ifl+. The transmittance of the same sample is 400X 10-7cm
2, the bulk density was found to be O-747j10n'' by the law. The body of the sample had good physical strength, and its rupture coefficient was I7-6 g/+nm2. However, as a result of cutting the main body for 1t, li, it has the drawback of closing the centerline part, which makes it unsuitable for many applications such as filtration of molten metal. 48j
It was found that it has a structure.

Reference Example 4 Another sample was prepared according to the method used in Reference Example 4, but differed in that the reduction rate of rolling and removal was controlled. In this example, the roll gap was adjusted to reduce the pressure by 86%, which is much larger than in Reference Example B.

The fired samples appeared to be strong, but had rather weak surfaces and edges that delaminated with rough handling. The transmittance of the same sample was measured to be 160'OX10-'cm'' and the bulk density to be O-39Ji'/on.The body has adequate physical strength and its rupture coefficient is 12. 7 g/wrn2.

When the main body was cut, it was revealed that it was entirely JC-, but the outer fibers were slightly thinner than the inner fibers, giving a weaker surface q-signature. This reasonably uniform body would be suitable for applications where surface strength is less important than overall uniformity and is not a drawback. However, since the main body is brittle, it is unsuitable for use as a filter for molten aluminum in q:i.

Reference Example 5 A sample prepared according to the method described in Reference Example 3 was
% (first pass) and 86% (second pass), respectively.

The fired samples were demonstrated to be durable with strong surfaces and edges. According to the measurement, the transmittance of the same sample was 1.700X1
0-7cm2, the bulk density is 064 L,! 7/c
It turned out to be m3. It was found that the main body has excellent strength, and its modulus of rupture is 19 g/flII++2. Body part'x I) J 1117 Then, it is distributed in JC- over most of it and
It was found to be unusually uniform with a moderate number of plugged pores.

This homogeneous, strong sample is suitable for limited applications such as filtration of molten metals.

Reference example 6 5 crn thickness, 12 holes per straight line 1 crn,
A sample of expanded polyester polyurethane was prepared and had an air permeability of 6000 x 10-7 cm.

The ceramic slurry used had the same composition as in Reference Example 3, but with the addition of some water. hK
It had a viscosity of 31 X i O” cps.

A sample of this foam material was impregnated as described in Reference Example 6. Slurry removal was carried out by two rolling treatments, with the first pass adjusted to a 62% reduction and the second pass adjusted to an 86% reduction.

The resulting sample was dried 1-1 fired and then tested and observed to have an air permeability of 1700 x 10-7 G+''. It had a uniform )zu9 structure suitable for use as a metal filter.

Reference Example 7 Processed according to Reference Example 60 procedure. What is the previous reference example?4
,700 x 10-7cm2
.

Different foamed polyester polyurethane was used.

In the same sphere, the viscosity of the ceramic slurry is 25X103cps
They were the same except that.

The treatment was the same as in Reference Example 3, except that excess slurry was removed by passing it through the rolls twice. That is, 84% of the pressure was reduced in the first pass, and 86% was reduced in the second pass.

The dried7 and calcined samples were equally strong and uniform;
There was no superficial weakness or obstruction of the central gland. This sample is 2
It had a transmittance of 650X I W7ttn2 and was considered suitable for use as a molten metal filter.

Unless otherwise specified, all percentages stated herein are percentages by weight.

As indicated above, the present invention provides considerable advantages in the filtration of molten metal, particularly aluminum lumen. Thus, for example, the present invention can be easily and quickly inserted into overloading devices.
Convenient 1: It can be easily and conveniently removed from the device.
A removable filter plate is used to allow the molten metal to be filtered. According to a preferred embodiment of the present invention, when utilizing a ceramic foam filter plate, the High filtration rates are obtained, and such efficiency is evident from the numerous applications of ceramic foam filters and the accompanying drawings illustrating their configurations.
This is accomplished by utilizing a disposable filter plate that can be easily and conveniently inserted into and removed from the filter device.

Filters are shown in Figures 1 and 2 as being within the molten metal A--JR, IJ equipment, injection pans, injection pipes, transfer pipes, metal processing basins, etc. If you wish,
The filter device λ2 may consist of two parts 2a and 2b which can be bolted together by any suitable device (not shown) such as a flange around its periphery. The particular filter loading shown and described in Figures 1 and 2 is a transfer having a central filter chamber 3 into which the metal exiting therefrom via outlet 5 is fed by inlet 4. The fj fusion Wm can be entered into the inlet 4 by some suitable device such as an injection spout (5pout) G. The filter chamber 3 is a doll-shaped chamber, and the nop in the same room is
It is recessed below the level of the inlet 4 so that molten metal entering the chamber can pass downwardly through the filter plate of the invention in place within the chamber. The filter chamber 3 is therefore characterized by a peripheral rim 7 which allows the upper part of the chamber to be completely accessed.As shown in FIG. It surrounds all sides of the filter chamber except for the adjacent sides.The filter chamber rim 7 is continuous with a side wall 8, which extends downwardly to the filter chamber floor 9, and the same method is used. is the sloped peripheral surface portion extending around M in the method so as to be aligned with the sloped wall surface of the filter plate, that is, the opening 1.
0 (Figure 2). The filter plate 11 has a corresponding sloped peripheral surface 12 adapted to align with the sloped peripheral surface portion 10 of the filter chamber. The inclined peripheral surface 12 of the filter plate 11 is provided with an elastic sealing device 13 that is resistant to molten metal, and the filter plate 11 and the moon device 13 are transferred to the filter chamber 3 and the filter plate 11 is connected to the C1 filter plate. A tight fitting device assembly is adapted to engage the sloped wall of the filter chamber.

Accordingly, the filter plate 11 is arranged substantially horizontally in the grate, as shown in No. 11>'J and No. 21:4.

As shown in the figure, this filter plate is square, but any shape such as round or hexagonal shape can be easily adopted as the filter plate depending on convenience. The filter plate 11 is the filter chamber, that is, the filter 4? - Floor 9 of Room 3 Place it in the recessed area where the VC is. The molten gold fS is passed to the filter plate 11 via the inlet 4 to the filter 3. The molten gold passes downwardly through the filter plate 11 and enters the recess 14 below the filter plate 11. The filter plate 11 is sealed in place by a 'zlt force suit' 13 so that it can be easily inserted by vertical upward pressure and easily removed by vertical upward pressure. . Alternatively, the filter chamber may be divided into sections as described above, with the same chamber 1. In order to fix the position of the sealed filter plate, a gas foot is provided at the bottom so that the filter plate can be moved from 1 to 4, and the filter plate is held in the same room by vise action. You can also do this. Preferably, the inclined peripheral surface portion 10 of the filter chamber is 2°IJ.
) and be inclined at an angle of up to 20° from C
The filter plate is preferably provided with an angular peripheral surface 12 of between 2° and 20°. The filtration ER @ 11 should be rotated to the output 15 and tilted upward at an angle of 1° to 5°, preferably at an angle of 5°, in order to prevent the intake of royal air from the same plate. Place it horizontally. It should be noted that the floor 15 of the recess 14 under the filter plate 11 is tilted downwardly by 1° towards the outlet 5 to facilitate the evacuation of the gold during operation and upon completion of the injection or transfer operation. It is cleverly inclined at an angle of up to 5°.

Alternatively, if desired, the filter chamber could be divided horizontally along a horizontal plane or at an angle below the floor 9, so as to facilitate cleaning of the recess 14 in particular. You can leave it there. It may be desirable to reverse the slope direction of the sloped peripheral surface portion to ensure sealing by the recess '14(/,)M portion.

! + 3, as shown in Figure h, the filter plate 1 of the present invention
1 has a sloped peripheral surface 12 adapted to align with the sloped peripheral surface section 10 of the filter chamber.

Design modifications such as those shown in FIG. 3B are, of course, contemplated within the scope of the present invention, in which the filter plate 11 is provided with a corresponding flat surface 16 adjacent to the sloped peripheral surface 12 all around its circumference. . Although Figures 6A and 3B show filter plates with sloped peripheral surfaces extending around the entire circumference, it is convenient to have
As shown in the figure, this is a case where the sloped surface does not extend around the entire circumference, but only around two sides of the plate.

Accordingly, it will be appreciated that the filter plate of the present invention can be conveniently used in a variety of locations, including pouring pans, pouring gutters, transfer tubes, pouring spouts, and metal processing basins. The filter plate is located in close proximity to the turbulent flow of molten metal, especially when
Such turbulence should not be placed where oxides are generated and entrained. This is the case in the case of turbulent flow both upstream and downstream of the filter plate. The turbulent flow that entrains oxides upstream of the filter plate can cause uneven flow in the filter plate, inefficient filtration, and in severe cases, premature blockage of the filter plate. It's a win.

The turbulence downstream of the filter plate negates the effect imparted by the filter plate, and the molten metal is again free of oxides or other non-metallic materials present or formed on the surface of the same metal. give a tendency to enter. A frequent source of turbulence is the furnace tap, gutter, and other devices that cause abrupt changes in the flow cross-section and thus increase velocity gradients. Of course, the particular filter mounting must be chosen with care so that it does not cause other turbulence. The above considerations regarding turbulence are, of course, particularly relevant to chemically reactive metals such as aluminum, magnesium and their alloys, which readily oxidize on contact with air;
Such considerations are also important for less reactive metals such as copper and its alloys. Devices for calming turbulence, such as suitably placed vanes, are of course available in the art.

As can be seen from the foregoing description, the filter plate of the present invention can be conveniently positioned substantially horizontally, and furthermore, if desired, the filter plate can be positioned substantially horizontally relative to the flow of molten metal. Do not place it perpendicular to or at an intermediate angle. The vertical arrangement of filter plates of the present invention is illustrated in the specific examples below.

However, horizontally arranged filter plates have two main advantages over vertically arranged filter plates. First, by taking advantage of the large length of the injection channel or the length and width of the injection pan, a large filter area is easily and conveniently available. On the other hand, in order to accommodate large filter areas with vertical mounting GJ, deep channels, pans or tundishes generally have to be resorted to. Such geometrical and dimensional constraints are often of great importance in practice, particularly when existing foundry applications are limited to window applications. A second advantage of the horizontal filter plate is that virtually the same static head of molten metal can be passed through all parts of the filter plate, whereas a straight filter plate can pass the metal from top to bottom. 1. Naturally connecting metal under the gradually changing head. It is in the fact that C. For this reason, the vertical filter plates naturally pass through the gold 8 unevenly. The top of a vertical filter plate will not pass the same amount of metal as the bottom of the same filter plate, and in fact may not pass at all. Once again in history
Variation of the head upstream of the filter plate has a greater effect on the vertical filter plate than on the horizontal filter plate, and temporarily or noticeably reduces metal passing through the top of the latter filter plate. There are times when I feel like I'm in trouble, and sometimes I don't even know what it's like.

In order to minimize the loss of 1" area through the metal during operation, the filter plate should remain buried under the minimum head of the molten metal 11. This is a horizontal filter, plate This is more easily accomplished by a vertical filter plate than by a vertical filter plate.Also, if the metal-impermeable portion of a vertical filter plate extends above the metal plane, this can occur under such conditions. Thermal stresses resulting from steep temperature gradients can cause cracks in the filter plate.For these reasons, horizontal or substantially horizontally arranged filter plates are preferred in the present invention.

However, a disadvantage of a horizontally arranged filter plate is that air can be trapped under the filter plate. This situation then leads to oxide formation downstream of the filter plate,
This can lead to drifting phenomena in the flow through the filter plate and therefore less than optimal filtration. Such air entrainment is eliminated by vertically arranging the filter plate.

According to the invention, the above-mentioned disadvantages of horizontally arranged filter plates are solved by tilting the filter plates at a small angle of 1° to 5° with respect to the horizontal, thereby reducing the wood quality of horizontally arranged filter plates. It has been found that this can be minimized while retaining all the advantages.

This positioning of the filter plate allows If4j to initially pass metal through the filter plate without having to discontinue the even or substantially uniform depth dipping of the filter plate, which is done in a horizontal configuration.
You can let the air escape. Preferably, as shown in FIG. 2, the high points on the surface of the horizontally arranged filter plate are arranged so that the escape of air is facilitated by the sweeping action of the four streams on the filter plate. It should be at the most downstream end of the plate. The feature of the filter plate arranged essentially horizontally and tilted upwards is very advantageous and can therefore be used, for example, when using separate filtration Gf Y and with filter plates in the same room. It will be appreciated that lesser results may be obtained without the use of a beveled peripheral surface, such as by holding the plate by vise-type action. Of course 1 m'fl
Preferably, the 40 bed 15 is also tilted as described above.

Figure 4 and! Figure 5 shows a vertically arranged filter plate installed in a transfer girder in accordance with the present invention.

In the embodiment of FIGS. 4 and 5, filter plate 20 is held in place by a refractory dam 21 and positioned within a slot 22 within filter chamber 23. In the embodiment of FIGS. The molten metal is passed through the inlet canal 24 to the filter chamber 23, horizontally into the filter chamber 25 and from there through the filter plate 20 to the outlet canal 26.
Go out. The filter plate 20 is fitted into the slot 22 by ceramic fiber gas nuts 27 which completely attach the plate.

Pre-wrapped gasket 7 filter plate 20. and dam 21 is placed in slot 22 and sealed in place by wedge 28. A drain hole 29 is provided for draining metal from reservoir 25 at the end of injection or transfer. During operation, the discharge hole 29 can be closed by means of a rod-shaped U-shape (not shown) or other convenient sealing device.

A filter plate, such as filter plate 20 of the present invention, has a trapezoidal shape I'! O
f) It is a three-dimensional garden-shaped fragment with both sloped sides, so that the peripheral mountain i of the board has the shape of a nail 1 slanted.

For the filter chamber 25 is the inclined peripheral surface 31 of the filter plate (
No. 01.4. ) to match the IC-compatible sloped wall surface 30.
(No. 4 and 1). Thickness in millimeters, surface L
A filter plate up to several square meters in size can be fed into the container as described above. The dam 21 and the filter chamber 23 are made of ordinary f'f construction material. The linings for the filter chamber 25 and the corresponding canisters may conveniently be made of high-strength lumber or ceramic tiles.

The dam 21 and the wedge 28 are 2. b'L eThe metal to be filtered is aluminum or some low melting point alloy.

If available, it may be made of a refractory board such as Marinite. Of course, mackerel! A-mounted bη27
&':r, preferably disconnected from the sloped peripheral surface 31 of the filter plate, but as shown in FIGS. If only the faces are beveled, the sealing device 27 preferably abuts the unbeveled peripheral face of the filter plate.

FIG. 7 shows the installation of a horizontally arranged truncated filter plate designed to feed a single inlet spout. The filter t:ξ plate 40 is installed in a recess 41 in the refractory bottom 42 of the pouring pan or tundish 43. f,'i iThe gold in the iron flows vertically from the pan 43 through the filter plate 40 into the groove 44 under the filter plate 40 and from there to the inlet spout 4.
It flows into 5 and is supplied to the ingot or @ object below it. This filter plate has an inclined JFM enclosure surface 46 to match the corresponding f3 [+i47] in the recess 41.
is provided.

An elastic sealing device 48 is provided in one plane of the corresponding double value ζζ, and the pre-sealed filter plate 40 is placed in place by applying pressure from above in the same manner as in the embodiment described above and honeymooned. I'll do what I do. Preferably, the rt of the filter plate
Some equipment should be provided to deal with air bubbles.

The invention may be embodied or carried out in other ways without departing from its spirit or essential characteristics.

Accordingly, the specific examples set forth above should be considered merely illustrative rather than limiting in any respect, and the scope of the invention is indicated in the appended claims, and the meaning and scope of the invention should be construed as indicated by the following claims. All such variations are intended to be included in the present invention.

[Brief explanation of drawings]

Fig. 1 is a top plan view of the filter chamber with the filter plate arranged substantially horizontally in the appropriate position, Fig. 2 is a cross-sectional view taken along the line...-■ in Fig. 1, and Fig. 6A is a FIG. 6B is a perspective view of a modified filter plate similar to that shown in FIG. 6A; 4 is a top plan view of another exemplary filter chamber having substantially vertically disposed filter plates therein; FIG.
A sectional view taken along the line v-■ in the figure, Figure 6 is similar to Figures 4 and 5.
FIG. 7 is a perspective view of the filter plate as shown in the figure, and FIG. 11.20,40...Ceramic foam filter. Agent: Akira Asari■563213 @July 21, 1975...■United States (US)■597963 0Inventor: Ropert K. Briuse 567 Ball Falls Road, Middletown, Connecticut, United States of America 0Inventor: Michael J.A.・Pryor 98 Maple Vale Drive, Woodbridge, Connecticut, United States of America 0 Inventor: Thomas G. Gray 3 Armsor, Halifax, Norpas Kosher, Canada (no street address)

Claims (1)

[Scope of Claims] (1) A ceramic foam filter having an open cell type structure used for filtration of molten metal, the structure comprising a number of interconnected voids surrounded by a ceramic web. Motivated by this, the above filter has a cost of 400 to 8,000. O
x I Q-7cnI” air permeability, Ll, 81)
-1], porosity of 95, pores per straight & t 1 i ~
20 (substantially uniform +1 (4)) having a pore size of IM1 and a thickness of 10 to 100 mm and having 9 homogeneously distributed pore openings throughout the foam. A filter made of ceramic foam, characterized in that it has a structure.
Preferably i ooo ~ 15 [JOXl (J-7c
Parallelism pass rate within the range of m'', O, aU ~ tJ, 95,
Preferably porosity of 0.85-0.90, straight line 1cTn
per hole size of 8-18, preferably 10-14, and 10-100111F1% preferably 65-6
The ceramic foam filter according to claim 1, characterized in that it has a thickness of 5 mm. (3) The ceramic foam filter according to claim 1, which has a property that gradually changes from coarse to dense over the entire thickness of the filter. (4) It has a property that gradually changes over the entire thickness of the filter, and one side of the filter has a thickness of 2500~a'o o o xl.
Air permeability in the range o -7 cm2, O,'90-
LJ, has a porosity of 95 and a pore size of 2 to 8 pores per linear cm, and the opposite side of the filter has a porosity of 400 to 25
00 x 1 (transmittance in J” cm2, [J, 80-
[J, 95 porosity and 8 to 18 pores per straight line 1α (+
? A ceramic foam filter according to claim 1, characterized in that the ceramic foam filter has a pore size of il.
(5) Open narrow IJ' characterized by a number of interconnected voids surrounded by a ceramic web
T! A high humidity resistant ceramic foam IQ filter having a mold structure and used for filtration of molten metals, having a density less than the 30th factor of the theoretical density for a ceramic material of the same diameter, and 40~ 95% Al2O3, up to 25% Cr2O3, 0.1-12% of a calcination product of bentonite and/or kaolin, and a hardening agent that does not substantially react with the molten metal, preferably aluminum orthophosphate. The ceramic filter made of ceramic foam according to claim 1, characterized in that it has a composition of 2.5 to 25% of baked products. (Claim filter made of ceramic encapsulation according to claim 5, characterized in that it contains 6145 to 55% Al2O3. (Characterized in that it contains 7110 to 17% Cr203) (8) A filter made of ceramic foam according to claim 5. (8) Claim H, characterized in that it contains 0.5 to 5% of a calcined product of bentonite and/or kaolin. Ceramic foam filter according to claim 5. 00) in the form of a plate with a corresponding sloped peripheral surface adapted to match the peripheral wall surface of the filter chamber and the removability, provided that the peripheral slope of the filter is A plate filter made of ceramic foam according to claim 1, characterized in that the filter is inclined at an angle of 2,000 degrees. A special plate filter made of ceramic foam according to claim 1U, characterized in that it has a device i+. h WF A plate-shaped filter made of ceramic foam according to claim 10. A plate-shaped filter made of ceramic foam according to claim 10. Claim 10 characterized by having a flat surface that is in instant contact with the surrounding slope and surrounds the entire periphery of the filter. Ceramic foam plate filter of (15) ceramic used for filtration of molten gold IB having a first open cell type structure characterized by a number of interconnected voids surrounded by a web of ceramic The foam filter has an air permeability of 400-8000 x 10-7 cm2, a porosity of 0.80-0.95, a pore size of 2-20 pores per 1 cm, and a pore size of 10-100 mm. A method of filtering molten metal through a ceramic foam filter having a thickness of
A process for filtering bath molten metal, characterized in that it is poured through said filter material at ri, thereby removing entrained solids from said molten metal. Transmittance of 0[112500~8(]00X10-72, Ll, porosity from 90 to 0.95 and direct Ha
Claim 1 comprising the step of prefiltering the molten metal through a relatively coarse ceramic foam filter having a pore size of 2 to 8 pores per cm.
071. The method of claim 16, wherein the prefiltration utilizes a series of ceramic foam filters with decreasing porosity. α8) The filter according to claim 16, characterized in that the preliminary filtration utilizes a single ceramic core filter having properties that gradually change from coarse to fine over the entire thickness. Method. 16. The method according to claim 15, wherein the molten metal is aluminum. (zul i Made of ceramic foam used for filtration of molten gold having an open cell type structure characterized by a number of interconnected voids surrounded by a ceramic web) Filter - C1400~8
000 x 10-7cm2) Air 'di Jl'!
- Porosity of 10.80 to 0.95, 2 pores per linear cm
In the method of filtration by a ceramic core filter with a hole size of ~20 and a thickness of 10-100 s++++, A, with a floor, an inlet of gold nuggets and a metal population, separated by a filter plate. B. providing a filter chamber having a wall surface suitable for the filter chamber; B. having a peripheral surface of said filter plate suitable for mating with a wall surface of the filter chamber; A resilient sealing device that can withstand the molten metal is provided on the surface, and the C6 filter plate and the sealing device are inserted into the filter chamber and fitted onto the wall surface of the filter chamber, so that the filter plate is said filtration device being arranged substantially horizontally and at an upwardly inclined angle of 1 to 5 degrees towards said metal outlet; A method of filtering a common θ; hammer, characterized by passing it through a plate, where the surface of the filter plate is kept below the level of molten gold. 21. A method according to claim 20, wherein the molten metal is slanted downwardly towards the outlet of the entire set. 400~8.00 for a ceramic foam filter used for filtration of molten metal with a timed opening structure.
Illusion transmittance of 0 x 10-7cIn2, 0.80~
In an apparatus for filtration by a filter made of ceramic foam having a porosity of 0.95, a pore size of 2 to 20 pores per 1 cm of linear ml, and a thickness of 10 to 100+++i, A, a bed, a metal A filter chamber having an inlet and a metal outlet and having a wall surface suitable for separation by a filter plate, B, substantially horizontally at an angle of 1 to 5° per hour towards said outlet;
filter chamber wall 1 inclined at an angle of , a filter plate having a peripheral surface mating with the ζ plane, C6 mating between said mating surfaces, resisting said bath melting force I; A device for filtering molten metal consisting of a resilient sealing device and characterized in that D. a filter plate separates the filter chamber and is easily accessible from the filter trap. c) The floor of the filter chamber under the filter plate is covered with the above-mentioned gold Ir.
23. The device O, according to claim 22, inclined downwardly towards the Is outlet.