DE1902844A1 - Compaction of grainy material - Google Patents

Description

TELEGRAMS: WESPATENT ₈ MUNICH 19 POST CHECK: MUNICH 1,51590 MONTENSTRASS E 9 / I

BANK H. AUFHÄUSER 379500 TELEPHONE 573203

Case IMI 44

Israel Mining Industries - Institute for Research

and Development, Haifa Bay (near Ir Oanim), Haifa, Israel

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Compaction of granular material

The present invention relates to the compaction of granular or granular materials.

In the manufacture of products from granular materials, for example ceramic materials or refractory

ir

most materials', represents the compaction of the granular material to bodies of the desired shape represent one of the essential stages. There are two main ways known for this purpose, namely (a) the wet processes and (b) dry pressing.

The wet processes are characterized by the fact that relatively large amounts of water or other liquid in the Orössenordnung of about 15 - 30 wt .- ^ are added to achieve the plastic state of the material or to obtain a slurry, and that the mass is subsequently is shaped under slight pressure or by pouring. This method always leads to products with relatively low densities. High density can then be achieved by sintering at high temperature, where-

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However, when you have to accept a high shrinkage, which of course represents a major disadvantage, "ί ^ r

The well-known dry compaction processes are characterized by is characterized by the fact that a relatively small amount of water or another liquid up to the order of magnitude of about 3.-7 ow.-jß is used and the shape the relatively nonplastic mass obtained in this way is made in molds in printing which usually in the range of 350-1000 kg / era.

The present invention seeks to provide an improved To create a dry pressing process that is suitable for compacting brittle, granular, non-plastic, non-metallic materials.

The mesh values given below are Tyler standard sieve sizes.

Generally speaking, many of the physical properties of an end product depend on; that is made of a granular material by compaction, such as, for example, the permeability or permeability, the thermal conductivity, the modulus of elasticity, the tensile strength and the compressive strength and the like, on the density of the product. - .... . . - - ' _r - "■ .- ■ -.- ■"

In addition, the volume weight can also have an influence on certain types of chemical resistance of certain materials in the sense that di® resistance with higher Volume weight increases «One example of this is silicon carbide.

Silicon carbide is a ceramic material known for its high resistance to fire and its high level of resistance, but in general it has a poor oxidation resistance persistent, which initially translates into an increase in weight

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and? then

certain changes in the dimensions of the swJJIfcfct: * this leads to the formation of cracks. Sixsfc can explain the weight va * & / k®m "^ flowering by the fact that silicon carbide, which has a molecular weight of 40 _{, is converted into SiO g} during oxidation, which has a molecular weight of 60 has * what the weight increase is based on. The silicon dioxide formed is usually grisitobalifr with a density of 2.32 in comparison to \ L · a density of 2.17 for silicon carbide, on which the enlargement of the dimensions and the formation of cracks are based »

Äusserdiem; take the high thermal conductivity and column strength * two of the valuable physical properties of bonded refractory silicon carbide materials, starting when the silicon carbide is converted into silicon oxide will.

It was found that the durability of silicon carbide against oxidation increases with an increase in density. This is shown in Table I below

T a be 11 e

Influence of density on SiC oxidation

Density of SiC samples-, g / cm- ^>

Increase in weight when initial burning

Further total increase in weight at 1000 ^e C weight · in a steam atmosphere near % hours

2.37 2.52

2.66

■ 3.4 0.4

0.8

0.25

0.2

5.1

3.65

0.6

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It has already been proposed to improve the resistance to oxidation by adding various reagents to the SiC during its molding. The products obtained in this way have, however, shown to be unsatisfactory because they have different bulk weights within the same body due to the non-uniform grain distribution in the particle size . According to another proposed method, the density of SiC is improved by filling the voids that normally remain in compacted granular material * with SiC particles «the liquid reagents converted into gaseous form in situ at temperatures above 1500 ^e C and preferably im High vacuum can be formed. However, this process has a number of disadvantages, namely high process costs, "inclusion of free carbon in the product due to the fact" that a stoichiometric reaction cannot be achieved in all phases of the grains, and restrictions on size and shape the body.

Loose granular material placed in a mold always occupies a volume that is considerably larger than that Volume is what it would take up if all the grains were in closest packing that physically is possible. If the loosely granular material in the mold is put under pressure, its packing becomes more dense, but it does * the material never reaches the theoretically highest density. Many granular materials can be in dry form under normal printing and shaping conditions ordinary temperature cannot be formed into a satisfactorily compacted mass.

Among the factors to consider for this, can be named the following! The surface properties the grains, the lack ari plasticity of the mass and the relative movement of the grains.

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The surface characteristics of the grains are determined by the shape of the particles and their areas and also by the functional properties of the grain surfaces and the adhesion at the points of contact. The lack of space in the mass prevents the filling of cavities larger than the mean grain size and of open spaces between the mass and the walls of the mold. A large relative movement of the grains is an important factor in achieving the highest possible packing density, since the particles can then easily fill any voids between the grains.

Various ways have been provided for the shaping to make it successful with granular material. According to one known processes, plasticizing additives are introduced The plastic mass, which contains the selected plasticizing additives, can easily be converted into the desired Shape can be brought without cabbage spaces between the particles. Two main categories of plasticizing additives can be distinguished

(1) Volatile lubricants or glidants, liquids, like water, or other liquids that can also contain additives, dissolved or suspended?

(2) Necessary lubricants, of which most of them remain in the mass to be formed after firing, such as clays (or other substances).

However, after the body has dried, when the liquid has leaked, pores appear between the grains, and so highly porous bodies are obtained that for many Purposes are unsuitable.

This attempt therefore leads, although it addresses the problem of Shaping solves, not to an end product with the required

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such properties. Ausssrdeia carries out the addition of large amounts of clays to contaminate the product with various undesirable components.

It is known * loose granular material without introduction of premd components with the help of hydraulic presses to condense. In this process, the powder to be compressed is first classified according to the usual methods * in order to obtain the correct particle size distribution that the existing packing densities result in *. Then the powder is placed in a solid steel mold and exposed to a pressure in the range of 0.3-5 t / cm, whereby the material is coherent and shaped in the contours of the shape I will. Because of the considerable prints required are for compressing large bodies, such as plates * large hydraulic presses and food ~ ". playful forms required. Even then, is the lifetime the forms briefly owing to the in these in all Directions for pressures applied for relatively long periods of time. It is because of these high pressures that the products made by this procedure are can, limited to bricks and smaller bodies.

In addition, the porosity of the end product obtained using hydraulic presses is still relatively high, and this condition cannot be improved for many small-scale materials by increasing the pressure. For example, moldings from corundum grains (96 % AlgO ^) were produced by pressing in a hydraulic press at 1.2 t / cm ² and 3 t / cm ² , and the same porosity values were found ^{after firing at 1600 9} Q. The corundum used had the following particle size distribution (weight Ji) t '

. . -10 Ji - 3 ♦ 8 mesh 25 $ - 8 φ ίο mesh 28 % - 30 + 90 mesh

1*

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$ 30 -320 mesh

The porosity of the moldings obtained was as follows

Pressed with a porosity of a Dsniok %

1.2 21

3 2.1

The same conclusions can be drawn from the densification of silicon carbide particles be pulled in a hydraulic press at different pressures »That was, for example with a Tellohen size distribution of the SiIiciuraearhids used from

64 $ - 14 + 24 mesh 17 $ 6 ■ '-100 4-600 mesh 19 % - βΟΟ mesh

the porosity of the bodies obtained is as follows

Pressed at porosity one pressure %

t / om ²

0.5 25.7

1.5 23.7

It is known from hot pressing technology to use fine powders Using submicron sized particles, resulting in a better compaction by closing the spaces between the particles due to the rapid sintering that leads to is made possible by the high activity of the grains. The grinding of some granular materials into fine powders however, poses a serious and costly problem. In addition, these fine powders show up when cold-pressed generally a relatively small amount of space, that is unsuitable for certain purposes. For example, "

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SiC (X) has a particle size distribution of 100 JST -325 mesh and (II) with a part size distribution from 100 j6 ~ 8. + 28 mesh after pressing in. a hydraulic press at 1 t / cm the following space requirements

SiC composition space ^ ewlcht % / gbt

II 2.26

Two other known Trookenverdiohtungsyerfahren in which very high pressures are used, the so-called blasting technology and the pneumatic mechanical technology. In the former technique explosive charges are placed around the material to be compacted, and in the latter technique a rapidly expanding oas is used to propel a bear at high speeds, for example on the order of 18 ra / eec or more. In both cases the pressures generated are extraordinarily high and have been calculated to be in the range of about 100-500 t / cm ² . These high pressures lead to serious practical limitations, since only very expensive molds made of special materials can withstand these pressures. These processes are difficult to control and reproduce, and in general the same limitations as given above for the di® hydraulic high pressure presses also apply in this case.

Regarding trooken pressing, it was also suggested that to use a so-called vacuum press. This press has a complicated shape or a complicated die that can be locked, and that within located mass is before and during the pressing process exposed to a vacuum. This procedure switches the handicap of air inclusion in the dry-pressed body, which reduces the porosity.

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However, the use of hydraulic systems remains
Fretting adhering to the above-mentioned restrictions on the shape and size of the au-generating briquettes. In addition, the process is a very slow process as it takes time to evacuate the molds and the process is much more expensive than the normal hydraulic pressing process «

Another well-known dry pressing process is what is known as press sintering. This method consists in pressing the heated refractory material in the mold so that the bond is made by welding the particles together while they are hot enough to have a certain amount of the vitreous component. The normally applied pressures are in the order of 1QOO 10,000 psi (70 -700 kg / cra ^s), and occasionally a pressure of about 40,000 psi ξ 2800 was kg / em ^S) with graphitfrelen Oesenken "It was AUOH a Drueksinterun «for ultra-high pressures up to. to. reported about 500,000 psi (25,000 kg / cm). The temperatures can be up to 2500 ° C depending on the raw material to be formed, whereby the high temperature makes the d18 particles softer and more plastic. The advantage of this process lies in the improved properties of the moldings obtained. These are characterized by the fine-grained shapes of the material, increased compression and increased pressure. This method, however, has become suitable for mass production due to the great difficulty

in the provision of molds * which can work at the required high temperature and yet a noticeable one Lifespan have proven unsuccessful commercially. Also because of the cost of this procedure it will only used for special goods.

Finally, there is also the so-called friction pressing process known. The type of press used in these processes

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■■■ ... - ■; ■. ■■ - - ίο - ■ '■ "■ · -.

is mainly suitable for plastisch® masses, i.e. metals. It does not lead to granular ceramic particles good compaction and it is generally for brittle materials not recommended * because the 'supplied. Energy is relatively low.

It follows that as yet no suitable method for dry pressing of hard and brittle granular materials. It is therefore the aim of the present Invention to provide such a method.

According to the invention, a method for shaping brittle and hard particulate! Created material to a h-earned ended body in which.

a) made of a material with a Young-Hodul of over 5.-10 .pei (0.35. Ϊ0 ⁶ kg / cm ² ) and an impact strength, determined according to the Charpy = test, of less than 10 lb.ft. (138 kgcm) a particulate mass is produced which contains coarse particles, the diameter of which is not greater than 20 mm, and in which the amount of fine particles with a diameter of up to about Z% of that of the coarse particles does not exceed jfö-'ίί ι

b) this particulate mass is placed in a © mold and this with a suitably shaped rigid KSr

. via closed Viird, the size of a Bnergi © in d®r £ on the order of 0.1. - Able to withstand 10.0 kgm / cm

c) this cup-shaped mass, while holding this body in between, is exposed to at least one blow or shock with an energy in the order of magnitude of 0.1-10.0 kgm / cm ² , around part of the grains of the particulate mass

to be crushed so that the pressure generated by the last shock or impact ^{does not exceed 50 t / cm 2 in} order to obtain a compacted body in which the amount mn

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crushed grains is at least 20 wt .- # of the total mass, based on the sieve analysis of the body ?. ™ ^α

d) the compacted body is removed from the mold.

As a rule, the compression according to the invention is at Carried out at room temperature. However, there may be cases at which a temperature increase is preferred in order to drive off residual water in this way. Any However, the increase in temperature should be controlled so that the above critical limits of Young's modulus and the Impact strength must not be exceeded.

Charpy impact strength is the energy expressed in foot. pounds (kgcm) for breaking a compacted Standard body by a sehl & pendulum that goes through swings a bow. The Young's modulus or elasticity is as the ratio of stress to strain within the elastic range defined.

If desired, the teleline mass can be in front of Bringing them into the mold to be shaped into grains or pellets it can also consist of two or more chemically different materials.

If desired, small amounts of water or another Liquid that is 6 wt .- ^ and preferably j> Wt .- ^ not exceed, incorporated into the particulate mass will. ;

In the case of the inventive device, the shocks are carried out with the help of a movable weight that, when the shock is delivered, has a speed in the order of J -8 m / seo. The pressures generated in this way are in the range between 1 and 50 t / cm ² . As a rule, it is preferred to apply more than one punch or push, as the density increases with each additional one

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Shock increases. The pressure in the mold is also gradually increased after each push. According to the invention, the compression ^{pressure should not exceed 50 t / cro 2} , and the number of impacts should not, as a rule, exceed 20.

The blows or bumps can be vertical or horizontal be directed.

It is possible to use die presses that are usually available to carry out the method according to the invention. According to the present invention, since the peak pressure inside the mold ^{does not exceed 50 t / cm 2} , an ordinary mold can be used without deformation which would occur if the pressure exceeded 50 t / cm ² .

In the following table II some materials are listed which can be compacted in granular form by the process according to the invention. The impact strength according to the Charpy test and the Young's modulus are shown for each material and it is apparent that these materials all have a Schlegzähigkeit below 10 Ib.ft (138 kgcm) and ei NEN Young's modulus of about 5 "10 psi (005 10 kg / cm ² ).

Table II

s 3S3SS asx

Impact strength and Young's modulus of some materials

Room temp era door

Material impact strength Young's modulus

Charpy test psi [kg / cm **] Ib. ft fkgoml

SiC 0.80 [11.04] (70-95) .10 ° _Ä

((4.92-6.68). 10 ⁶ J.

MgO 0.75 hO, 353 50.10 ⁶ f3 # 52.1G> ⁶ J

Corundum 1.15 [15.87] 58.10 ⁶ (4.08.10 ⁶ J

Silica glass <1 fr}, 8] 10.5.10 ⁶ (θ

Mulit β ΑΙλΟ ,. . f- f-

2 SiO ₂ * 4-5 f55-69J 21.10 ° (1.48.1O ° J

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material

Impact strength Charpy test lbeft [kgcm] Young modulus pel Tkg / ora ² ]

Cordierite Steatlt
SlOg (quartz) bauxite

4.3 [59.4} 5.1O ⁶ [0.35.1Q ⁶ 3

4.8 [66.24] 10.1C ⁶ i0.74.10 ⁶ J.

<5 B693 14.7.10 ⁶ [1.03.1C

0.8-1.1 [11.04-15.183 (40-50) .10 _v ⁶ *,

Zirconium oxide <

Zircon

(ZrOg.SiO ₂ ), soda-lime glass (nun! Glass)

Glass ceramic (degassed)

Borosilicate glass (Pyrex)

5.5 [75.93 C1 [<13.83 0.5-0.6 [6.9-8.283

1 [13.83 20.10 ° (gtab.) 36.10 ° iunstab.)

13.6.10 ⁶ [0.96.1O ⁶ 3 10.10 ⁶ [0.74.10 ^{6 y}

(12-20) .10 ⁶ _k . [φ, 84-1.4ΐ) .1Ο ⁶ ]

(8.8-9.5). 10 ₆ UO, $ 62-0.6 10 °

). 10 ⁶ ₆ 6 $. 10 °

For comparison purposes, there are three in Table III below Materials indicated that are not according to the invention in granular form are applicable.

Table III

Impact strength and Young's modulus of some materials

at room temperature

material

Impact strength Charpy test Ib.ft [kgcm'i Young modulus psl (kg / era ² )

Steel alloy 10-25 [138-J545J

Monel metal Styrene polymer (25-30) .10 ° 10.76-2.1 ψ 10 °)

150-233 [2070-31743 25.10 ⁶ [i, 76.10 ⁶ 3

0.25-0.9 [3.45-12.42] (0.2-0.5) .1of ,

W, 014-0.035 ^ 10 °]

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From Table III above it can be seen that steel alloys and Monel metal, both of which are hard materials are unsuitable for the purposes according to the invention because of their too low brittleness at room temperature, while styrenic polymers are known as brittle materials are unsuitable due to their softness and plasticity.

As already stated, the Teilchengrössehverteilung in the introduced in the form of particulate mass should be such that less than j5O # fine particles are present, wherein the fine particles are defined as those Defi- \ having a diameter up to 2% of the Durchmeß "sers of the coarsest grains present in the mixture, the diameter of which does not exceed 20 mm. The reasons for this are that the compression according to the invention is based on comminution, which is due to the fact that there is no plastic flow of the grains, which in turn occurs the absence of plastic materials. The smaller the particles, the less suitable they are for comminuting. However, since according to the invention the amount of comminuted grains should amount to at least 20% of the total amount, the above-mentioned limitation of the particle size distribution is the part * Elevated mass is critical.

The procedure according to the invention is for you Manufacture of composite bodies from two or more different particulate materials as the case may be usable for special requirements. For example, compacts made from a mixture of SIC and Mullifc are distinguished by a higher temperature resistance and also by a higher resistance to oxidation compared to SlC. The presence of mu11ite continues the oxidation of the SiC grains, especially under the conditions of high compaction resulting from the new compaction process »

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In general, the bodies made from these two components do not require engobe, as the SiC grains through the mullite are anchored. In special cases in which an engobe is desired, however, this can be used \ <because it adheres very well, even better than on shaped bodies made from silicon carbide alone.

During each hit or jolt, the contact time is in the case of the merit longitudinal method according to the invention Usually less than 10 seconds and in many cases is even less than 10 seconds. In contrast to this is the pressing time in hydraulic presses in the order of seconds. In the method according to the invention, the shock waves of the so-called explosion process mentioned above, which has the advantage that the shape is not so rigid suffers as with the hydraulic pressing process · At the same time, the process according to the invention is superior to the explosion process in that the results are much better reproducible.

The following examples illustrate the invention without restricting it.

example 1 Manufacture of SiC panels

A mass of silicon carbide grains obtained by mixing 20 # 8-10 mesh particles, 70 % 14 F particles and 10 % DCF particles was compacted into plates of 10 χ 10 cm in an impact press using a weight of 130 kg, which fell from a height of 1.8 m. The initial thickness of the plate was 12.7 mm and the final thickness 10 mm.

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Blow - 16 - acceptance
in
the height
in min 1902844 Total-
pressure"
t / οπΓ η % of the
velvet =
decrease
the plate 1.8 Total force
kg (Hasse)
in / jsecS 1.3 After the 1st η 67 0.38 12.7.10 ⁵ 6.1 H «2. η 14th 0.24 60.4.10 ⁵ 9.6 η Η-ζ
J * η 9 0.16 95.7. 10 ⁵ 14.4 ■ ^H 4. 6th 0.11 14 ^ 5.10 ⁵ 22nd " ⁿ 5- 4th 2087.1O ⁵

After the 5th blow, the plate had a density of 2.66 and a porosity of 16 # on *

The sieve analyzes of 14 F and DCF are the following %

14 F.

DCF

+ 10 mesh 2 Weight + 100 mesh 6.2 Weight -10 + 35 mesh 50 Weight + 325 mesh 10.8 Weight -35 + 100 mesh 22nd Oe w, + 400 mesh 7.2 Weight -100 + 325 mesh 22nd Weight -400 mesh 75.8 Weight -325 mesh 4th Weight Example 2 The extent to which the grains are crushed during compaction
according to the new inventive method \ -f> -100 > · * -325 'Γ * .- *

10 × 10 cm sheets of SiC were produced in a closed mold by compaction in an impact press using a 140 kg weight. After compaction, the Siabanalyce of the grains in the plates was compared with the sieve analysis of the material "ü" before compaction and it was found that particles were crushed during the blows in the impact press. The results are given in Table IV below.

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BATH ORIGINAL

Table IV

fine particles

CD O CO QO CO CO

cn

fine particles

Mixture No. I. Original part

small size division

after 4 blows from a height of 1.8 m sample 12 now (thick sample)

4 5 6

after 4 hits - after 16 hits - after 16 hits from 1.8 m from 0.45 m from 0.45 m in height Height, sample 6. Height, sample 12 sample 6 mm mm (thin sample) mm (thick sample) (thin sample)

8/14 mesh (coarse) 64 23.6

- 14/10 mesh 25 * 5 51 * 7

1100/325 mesh) 17 * 0

) 10.5

ι-325 mesh) 7 »6

18.6

51.5 20.4

9.5

29 * 5 47.5 14.3

8.7

25th

52.5

14.3

8.2

Volume weight

g / enr

2.67 2.67

2.66

2.66

Mixture No. II

after 4 blows from 1.80 at the height of the sample 12 mm (thick sample)

after 4 hits after 16 hits after 16 hits

from a height of 1.80 m from a height of 0.45 m from a height of 0.45 m

Sample 6 mm high, sample 12 sample 6 mm

(thin sample) mm (thick sample) (thin sample)

8/14 mesh (coarse) 71.5 21.7

14/100 mesh (medium particles) 28.5 52.3

) 100/325 mesh 21.7

) -325 mesh 4.3

17 * 2

52.5 23.1

7 * 3

27.4

52.3 16.2

4.0

22.4

55 * 4 15.7

6.3

Volume weight g / enr

2.65 2.65

2.66

2.66

CD CD KJ 00

In all cases the depth of the crushed grains was more than 20 wt .- ^. This crushing rate was high favored by the relatively low content of fine particles which prevent the crushing effects.

Example 3 Dependence of the room used on the supplied energy The energy input is proportional to the following product Weight χ Fall distance χ Number of blows®

A number of tests were carried out with different materials and each material was exposed to two different sources of energy ι It was found * that with the same material the room is accorded with the Energy supply increases. The results are given in Table V below.

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Tabel Volume weight of products obtained by the impact molding process

Particulate particle size material distribution

Distance of the weight number total room weight falling of the energy ■ * weight in beats kgm / cm ² g / cnr m kg

CD O CD CD C *> CD ^ O

quartz

corundum

Silicon carbide

600-10 + 14 mesh
200-100 mesh
200-400 mesh 1 N 1.8 600-8 + 24 mesh
250-JO + 9O mesh
100-100 mesh
50-325 mesh 1.18 ti 1.18 60.70-8 + 46 mesh
230-46 + 320 mesh
10.20-320 + 600 mesh
6.10-600 mesh 0.54 It 0.54

130

15th

15th

8.15 15 * 1

4th
4th

7th
7th

12.7 2.08 22.9 2.27 10.5 3.18 21 3.27 30.6 2.50 56.7 2.64

The total energy can also be increased without changing the weight », the distance or the number of blows by accelerating the blow weight. This can be done by a thrust "produced by springs", steam or compressed air *.

Example 4

Comparison of the density achieved according to the invention with the density achieved with the aid of a hydraulic press

A number of particulate materials were used in accordance with the invention and by means of a hydraulic press of prints »as they are usually used in industry» i.e. in the order of magnitude of 1 - J3 t / cm, compressed. The results are given in Table VZ below.

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! NSPHCTED

Table VI

O CO CO U) CO

Comparison of the results achieved by the new impact pressing process and by means of a hydrau
Italian press achieved density Particle
size
distribution Compression using < number
the
Blows height in an impact press space
weight Compression means of a hy
draulic press space
weight
g / cm3 t
(O Particle
shaped
material 6OJ6-1O-M4 mesh
2O56-IOO mesh
2056-400 mesh Blow -
weight
lay 4th 1.8 Total-
energy
fcgm / era ² 0.27 pressure
t / cm ² 2.11 -1 quartz 60.7 * -8 + 46 mesh
2356-46 + 320 mesh
10.256- ^ 20- ^ 600 m
6.156-600 mesh 10 1.4 22.9 2.58 3 2.40 [Silicon
carbide It ~ V
esh
ΓΤ5 8th 1.5 10.7 2.71 1 2.65 η 6056-8 + 24 mesh
2556-30 + 90 mesh
IO56-IOO mesh
556-325 mesh 8th 1.2 37.8 3.22 3 3.05 corundum
(96 * η 15th 6th 1.2 10.5 3.27 •1 3.26 η 15th 21 3

Example 5

Spheres with a diameter of 5 cm were made from different batches of silicon carbide with the following particle size distribution :

10056 -35 * ^ 6 mesh II (8556-35 * 46 mesh

-200 mesh III (85 # -35 * 46 mesh

($ 15-600 mesh IV

-Ö4-8 mesh 2% -35 + 46 mesh

16 # -325 mesh -325 mesh

The volume weights of the spheres were as follows:

Together'·
Settlement T a be lie VII number
the
Sleep 10 height
m Volume weight = <== «== ===== ge 10 g / cnr attempt Impact press method 10 v, 4 I. weight
kg 8th 1.4 2.59 II 8th 1.4 2.55 1 III 15th 1.5 2.46 2 IV 15th 1.5 2.78 3 V * 15th 2.0 4th 8th 5 8th

It should be noted that from the above results it can be seen that batch V, which is exclusively
consisted of fine particles, into a protjukb with

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tem density led »which shows that the restriction the amount of fine particles in the particulate mass should not exceed jJO wt .- ^.

Example 6

Comparison of the porosity of the product obtained by the process according to the invention with the porosity of the product obtained by using a hydraulic press

A number of different particulate masses have been subjected to compaction in accordance with the invention and compaction using a hydraulic press

subjected to pressures of 1-3 t / cm, and the porosity of the products has been determined. The results are compiled in Table VIII below. It can be clearly seen that the porosity of the moldings produced according to the invention is considerably lower than that the briquettes produced with the aid of a hydraulic milling machine 1st.

H Ü 9 H: <9 / Π ? R.

Table VIII

CD O CD OO GO CD

cn

i With - small plate-shaped -
play all material Particle size
distribution I. Impact press Total-
energy
kgm / em ² Poro
sity Hydraulic press porosity 1 quartz 6O # -1O * 14 mesh
SG ^ -Ii QO mesh
2Q & -400 mesh number
the
Blows 22.9 ^ 4.5 pressure
t / cm 20.3 2 corundum 60ji-8 * 24 .mesh
255 »-pO + 9O mesh
10 ^ -100 mesh
5 # -225 mesh 4th 21 16.5 3 22nd 3 silicon carbide 60.7 ^ -8 + 46 mesh
23 ^ -46 ^ 320 mesh
1 ©, 2ji-320 + 600 mesh
6.1 ^ -600 mesh 6th 37.8 12th 1 23.0 4 silicon carbide .2 * 5.3Ji-S * 10 mesh
14J6-14 * 24 mesh
25 ^ -100 * 6 (00 mesh
24.8 jg-600 mesh 8th 37.8 14.5 1 20.0 5 silica glass »5 ^ -8 ^ 2 ^ -nrsesh
35 ^ -24 * 100 mesh
2C "^ - i00-s-200 mesh
1Q £ -200 mesh
IC ^ -325 nsesh 8th 12.7 16.5 1 29o 6 ^M.
t 4th - "i 24.8
' 3

ro

■ * = ■

CD O NJ OO

Example 7 Proof of the glelohförnlgen Raumgewlohts

Silioiuracarbldkugeln (SiC) were made from grains with follow « the Tellohen size distribution made:

20? -6 +8 mesh 70Si 14 p ΙΟ * DCP

where 14 P and DCP are as defined in Example 1.

In three different experiments balls were produced »with the grains in a shape up to different heights were introduced. In each case the form was forgone Ben and 4 beats weighing 130 put one Distance of 1.8 m fell through, so that the total supplied energy was 21 kgm / cra in each case.

The results were as follows: Table IX

Height of the compacted space-weighted body,

cm g / onr

0.96 2.71

3 2.70

6 2.70

The last Pormling was cut into several pieces. Each of these pieces had the same volume density of 2.70 g / cm · '.

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Example 8

Manufacture of a composite plate from silicon carbide and aluminum oxide

60 g of aluminum oxide powder, mixed with 3 g of an aqueous one Sulphite liquor solution »was at the bottom of a fluffy iron mold from 10 χ 10 am distributed and leveled. A mixture of 500 g silicon carbide (60 £ -20 * 24 mesh; 20 $ -30 +90 mesh and 2055 -90 nesh), which is also 30 g an aqueous sulphite solution contained »applied and also distributed and leveled.

An equal proportion of the aluminum oxide powder mixture as above was applied on top of the two sections. After attaching a cover iron plate to this arrangement was the mold placed in the impact press »in which a weight of 100 kg fell three times from a height of 1 m« The composite panel obtained contains a top layer and a bottom layer made of aluminum oxide with a thickness of 2 mm and a middle layer with a thickness of 18 ram made of silicon carbide. The density of the silicon carbide was 2.6.

Example 9 Manufacture of silicon carbide pipes

300 g silicon carbide (6o # -20 4-24 mesh »20 $ -30 · # · 90 mesh and 20 £ -90 mesh) containing 15 g of an aqueous sulfite liquor solution was placed in a suitable mold of 7 x 15 µm , which was formed from two concentric Elsen tubes. After the mold had been placed in the impact press, the upper section was compacted by 3 blows with a 100 kg weight from a height of 1 m. A pipe 7 cm in diameter with a wall thickness of 5 mm and a density of 2.65 was obtained.

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Example 10 Manufacture of Siliciuracarbide crucibles

Crucibles were made in the same manner as above using the same mixture by introducing a bottom section prior to pre-pressing by the blow. A crucible of 7 x 12 cm with a space was made. weight of 2.65 received.

Example 11 Manufacture of zirconia oxide .

A zirconium oxide stone was made from grains of calcium stabilized zirconium oxide »which had the following particle size distribution:

- 14 mesh ψ 24 mesh 55 * - 30 mesh -100 mesh 255 * -100 IS * -J525 5 #

The grains were mixed with 2 l of an aqueous sulfite liquor solution and the mass was placed in a closed mold. The mold was placed in an impact press, in which 6 impacts with a base weight of 135 kg were performed from a height of 1.5 m. The Raumgewloht the stone was before d> sm burning 4.45 g / cm ^.

Example 12 Manufacture of mullite balls

Mullite grains (3Al ₂ O, .2SiO ₂ ) with the following ^F i: L lohen size distribution s

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ORlGiNAL INSPECTED

190284A

- 4th + 20 mesh 40 * -20 + 65 mesh 20 * -65 +100 mesh $ 20 -100 mesh 20 *

were mixed with 2 * an aqueous sulphite solution. The mixture was placed in a closed mold » to get a bullet. The mold was placed in an impact press "in which 6 blows with a hammer weight 135 kg dropped from a height of 1.5 m, were carried out. Before firing, the ball obtained had a density of 2.4 g / cm ·

Example 13 Manufacture of a silicon carbide / frullite Qemiaohs

A mixture was prepared from silicon carbide (~ 8 <t§4 mesh) and mullite (50 * -30 «90 mesh, 50 * -100 mesh) in a weight ratio of 1 % 1. 5% of an aqueous sulfite liquor solution were added to this mixture, and the mass was placed in a mold to produce a housing with a diameter of 22 cm and a depth © of 4 cm. The mold was placed in an impact press, in which 3 blows were made with an impact weight of 140 kg dropped from a distance of 1.4 m. The casing obtained had a volume density of 2.6 g / cnr before firing.

"Multiple firing at i400 ^e C, the body exhibited a very low oxidation to (0.2 * after 500 hours at 1000 ⁰ C in a steam atmosphere).

Example 14

Manufacture of bauxite stones

A stone was made of bauxite with the following particle size distribution 909839/0254

- 8 424 mesh 6o £

-30 +90 mesh 255 *

-100 mesh +525 mesh $ 10

-325 mesh

manufactured. To this mixture, 3 l of an aqueous sulphite solution were added. The mass was placed in a closed mold and the mold was in brought an impact press. In the press, 4 strokes with a sole length of 130 legs were made from a distance of 1.8 ro executed. The density of the stone was before burning 2.97 g / cm

Example 15 Production of moldings from pearl class

Cylindrical bodies were made by mixing 100 g of pearl class (Tellohen size distribution! 13 $ -3 2 mesh, 50 $ -6 +20 mesh, 10 $ -20 -9-100 mesh and 25 $ -100 mesh) made with 2 g of water and 2 g of glycerine and placing in a mold with a Durohmesser of 5 om. Form was placed in the impact press, sealed and hit by 5 impacts weighing 135 kg from a height compressed by 1.8 m. The cylinder obtained had a volume weight of 2.97 g / om ^ before firing.

The new method according to the invention is characterized by its flexibility, which enables a wide range of solid and hollow bodies and also KÖ2? @m, in which layers of different materials are arranged on top of each other, to be produced in an easily reproducible manner. When carrying out the process according to the invention For example, simple closed shapes made from ordinary thin strips of pin held together by two or four studs can be used. This is due to the fact that the ttuf-

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T902844 - 30 -

Due to its very short duration, the applied force actually only acts in one direction. This makes a clear one Advantage over the complicated and expensive ones Forms "as they are used in some of the known presses for forming plastic masses".

Example 16

Manufacture of composite materials from SLC with a phenol-formaldehyde resin and from a SiC-carbon composite material

Dl grains of SiC from two selected Tellohen size distributions were coated with a phenol-formaldehyde prepolymer "which is known under the trade name Novolack". For this purpose, the novolak was dissolved in (SM) H and mixed with a small amount of the SiC grains and a little hexamethylenetetramine (about 10 ow.-ίέ, based on the novolaok). After mixing, the mixture was dried in vacuo at 60-70 ° C. The dried SiC grains "which were coated with Novolaok" were somewhat agglomerated. The agglomerates were then crushed into -4 mesh particles. Small cylindrical shaped bodies were produced from the coated grains by compacting them with the aid of a drop hammer in a closed steel mold and then hardening them in the mold under low pressure at 160.degree. The procedure was as follows

The grains were placed in a cylindrical mold with a diameter of 1.8 cm and pushed through a weight of 130 kg "which fell from a height of 25 cm". The number of strokes is given in the table below. Subsequently, the formed aggregate was placed between two round iron plates »which were tightened with four screws» to exert some pressure on the moldings »and the aggregate was then placed in an oven for hardening at 160 ° C. The H "rtungsbedlRgung®n Sinoe Xn of

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Table X below. Due to the distance between the mold and the stamp, the 'base could escape * Naoh the moldings were removed from the molds after curing.

After removing the moldings from the mold, their density and their cold pressure strength were determined. Some of the moldings were charred * around SiC-carbon composites to obtain. The charring was carried out in an oxygen-free nitrogen atmosphere, while the temperature was as indicated in the table below Heating scheme has been increased to 900 * C. Before heating was the system purged with nitrogen. After carbonization, the specific gravity and the cold compressive strength of the Moldings determined "From the results given in Table X it can be seen" that the molding method according to the present invention is very suitable for the production of Siü-phenol-formaldehyde resin bodies and of SiC-carbon composites made from the latter are suitable » whereby high compaction wires are achieved. It formed there are no cracks in the molds during the curing and pyrolysis stages.

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BAD ORJGJN _AL Table X

co O CD 00 CO CD

material Phone size number of Weight # Weight £ Hardening Hardening distribution Blows at at Time temperature mesh % SiC resin min • c 1) SiC + -4 +6 50 NoYolack + Ψ100 15 Hardening agents -100 10 320 25 6th 90 10 60 160 2) SiC Ψ -4 +6 50 Νονόlack + 46 15 Hardening agents 320 10 600 25 8th 90 10 75 16O

Table X (continued)

co CD CO 00 GO CO ^ * O κ> cn

Ma
te Diohte of the Fomlings after
Pyrolysis Xalt pressure resistance after
Pyrolysis
kg / cm Pyrolysis under N ₂ rial >
"at - ror the
Pyrolysis 2.50 before the
Pyrolysis
kg / cm 315 D. 2.72 1170 not pyrolyzed 2) 2.60 - 1 h 160 ° C
1.5 h 260 * C
1.5 h 400 * 0
2 h 600 * C
2 h 900 * C

I V *

CD O

00

Claims (12)

Claims 1. Method of shaping brittle and hard particulate! Material to a compacted molded body, thereby marked that a) made of a material with a Young's modulus of over 5.10 ^ psi (0.35.10 ⁶ kg / cB » ² ) and an impact strength, determined by the Charpy-Tesfe, of less than 10 lb.ft (138 kgom) in a single partial shape A mass is produced which contains coarse particles, the diameter of which does not exceed 20 mm, and in which the amount of fine particles with a diameter of up to about 2 % of that of the coarse particles does not exceed JO%, b) this particulate cash register is placed in a mold and this is closed by means of a suitably shaped rigid body, the interference from an energy of the size can withstand an order of 0.1 - 10.0 kgm / em, c) this Teiloheniform mass is subjected to at least one impact with the interposition of this body, the one Energy in the order of 0.1-10.0 kgm / era has to comminute part of the grains of the particulate mass in such a way that the pressure generated by the last impact ^{does not exceed 50 t / cm 2} , in order to produce a compacted molded body obtained, in which the amount of crushed grains is at least 20 dew · - £ of the total mass, based on the sieve analysis of the body *, and d) the compacted molding is taken out of the mold " 2. The method according to claim 1, characterized in that up to 6j (of a liquid in the pellet-shaped mass be introduced into the mold prior to introducing the same. 909839/0254 "'■■■ - 35 - 5. The method according to claim 1 or 2, characterized in that silicon carbide is used as the material. 4. The method according to claim 1 or 2, characterized in that corundum is used as the material. 5. The method according to claim 1 or 2, characterized in that quartz is used as the material. 6. The method according to claim 1 or 2, characterized in that zirconium oxide is used as the material. 7. The method according to claim 1 or 2, characterized in that periclase is used as the material. 8. The method according to claim 1 or 2, characterized in that silica glass is used as the material. 9. The method according to claim 1 or 2, characterized in that mullite is used as the material. 10. The method according to claim 1 or 2, characterized in that the particulate mass consists of two or more chemically different materials is produced. 11. The method according to claim 10, characterized in that a mixture of mullite and silicon carbide is used will. 12. The method according to claim 10, characterized in that that a mixture of silicon carbide and Pk-nol-formaldehyde prepolymer is used, U. The method according to claim 12, characterized in that there is no core, that the compacted molded body obtained in a *., * oxygen-free atmosphere with the formation of a merit », m Silicon carbide-carbon composite body caloinated »d. 909839/0254 19Q28AA 14 · The method according to any one of the preceding claims «characterized» in that the particulate mass is two or multiple impacts * 15, the method according to any one of the preceding claims "characterized" that the impacts are generated by a moving weight "the one at the impact Has a speed in the order of 3 to 8 m / eec. 808839/0254