DD205126A1 - METHOD AND APPARATUS FOR PRODUCING AL DEEP 2 O LOW 3-CERAMIC BODIES - Google Patents

Abstract

The invention relates to the production of microbores in the range not equal to 50 microns in Al deep 2 O deep 3 ceramic bodies using the sintering shrinkage, with highly disperse gamma-alumina isostatically pressed at a pressure of not equal to 50 MPa with insertion of a pressing needle to a blank, then the crimping needle is removed again and then the microbore is ground free by white machining and finally the over-turned blank is sintered. The aim of the invention is to improve the geometry and the surface of the microbore, whereby the sintering shrinkage of the blank increases and an accurate fixation of the pressing needle should take place. According to the invention, therefore, the highly dispersed gamma alumina used is pressed only in the radial direction of the future blank, while compaction in the axial direction is as completely as possible prevented. The invention can be used, for example, for the production of capillary carbon tools.

Description

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WP B 28 B / 238 906-0

Dipl.-Ehys. Rolf Bahn P 869

IPK; 28 B _f 3/00

Title of the invention

Method and device for producing ceramic bodies

Field of application of the invention

The invention relates to the production of y ceramic bodies with micro-bores in the range -50 μm using the sintering shrinkage. Such bodies are used for example as Kapillarbondwerkzeuge in automatic bonders for bonding integrated circuits or spinnerets.

Characteristic of the known technical features

It is already known to produce A1 ~ O ^ ceramic bodies with such microbores by exploiting the sintering shrinkage. This is from fumed ^ clay with insertion of a pressing needle whose diameter contains a Schwindungsaufschlag of about 60 % to the desired microbore diameter and a conical tip

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Consequently, with a pressure of $ 50 MPa in an isostatic way, under blanket pressure transfer - pressed a blank. Then you remove the crimping pin and presses in their place a Einstecknadel with the same diameter in the blank. The hole is then sanded free by white machining. Then, the sintering of the thus processed blanks takes place under a hydrogen atmosphere at temperatures between 1700 and 1750 ⁰ C (DD-PS 146 909).

The pressing of the blanks takes place on the usual isostatic pressing, in which a flexible mold is arranged in a recipient. In this way, in the shaping of the pressure on the located in the flexible form AIpOo powder is transferred on all sides (DD-PS 86 771).

However, there is the disadvantage that the geometry of the microbore and the surface quality at the Eingangssbzw. Output opening often do not meet the requirements, so that reworking are required. In this way, however, the formed on the surface of the microbore burning skin is injured and thus reduces the abrasion resistance. Lower tool life is the result.

Object of the invention

The aim of the invention is therefore to improve the geometry and the surface of the microbore produced and thus the service life of the tools.

Explanation of the essence of the invention

The invention is therefore based on the object of

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drive and a device for the production of ₂ ceramic bodies with microbores in the range ^ 50yum to make use of sintering shrinkage, wherein a highly disperse ^ -ton earth isostatically pressed with a pressure of ^ 50 MPa with insertion of a pressing needle to a blank, then removed the baling needle and then, by white machining, the microbore is ground free and finally the over-rotated blank is sintered. In particular, the sintering shrinkage of the blank is to be increased and an accurate fixation of the pressing needle to be effected.

According to the invention, this is done by the highly disperse ^ clay is pressed only in the radial direction of the future blank, while a compression in the axial direction is completely prevented as possible.

This method is realized with an isostatic press which consists essentially of a flexible mold with a support body, which are arranged in a conventional recipient.

According to the invention, the flexible mold is designed as a compression sleeve whose axial openings are closed by unyielding plugs (4), wherein the edge of the plugs (4) projects beyond the outer contours of the compression collar (2). The ferrule is surrounded by a perforated tube (3) supported on the edges of the plugs (4) and one of the plugs has a bore through which the plunger (1) is fixed.

Since of the mold only the sleeve made of flexible material, while the two axial openings are made by plugs of unyielding material whose edges are supported on the perforated tube against each other, the compression of the blank takes place substantially only in the radial direction. With the help of the hole in the bottom plug, the inserted needle is also during the

• w 4-

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Pressing securely fixed,

Useful example

By way of example and with reference to the drawing, the invention will be explained in more detail. The drawing shows the press cuff with plug in section.

The production of capillary carbon tools takes place as follows:

From a highly dispersed / clay soil with a BET surface area of> 100 m / g, a pressed granulate is produced with the addition of 3 % polyvinyl alcohol. The rubber press collar 2 is closed at the lower side with the stopper 4 made of metal. Thereafter, a perforated tube 3 is slipped over the cuff to support the cuff. In the hole located in the center of the plug then the Preßnadel 1 is inserted and thus fixed. The crimping needle has a conical part (16 °), followed by a cylindrical part at the tip. The diameter of the cylindrical part of the pressing needle is 75 / um, the length 0.3 mm. In the closed in this way at the lower end press cuff, the pressed granules are filled and then the upper end of the sleeve is closed with a stopper 4 made of metal.

The pressure cup sealed in this way is brought into the recipient of an isostatic press, not shown in the drawing, and the packing in the cuff is compressed under a pressure of 50 MPa. The pressure medium presses on the flexible rubber sleeve, which yields radially under this pressure. The axial pressure on the metal plug 4, however, is intercepted by the perforated support tube 3, so that a compression in the axial direction is prevented. After opening

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the crimping cuff, the crimping pin can be easily pulled out of the blank. Subsequently, the free grinding of the bore by white machining. After sintering at a temperature of 172O ⁰ O under a hydrogen atmosphere, the diameter of the microbore is 50 yum.

Claims (2)

invention claim 1. A process for the production of Al ₂ Oo ceramic bodies with microbores in the range ^ 50 / um taking advantage of sintering shrinkage, wherein a highly disperse ^ -ton earth isostatically pressed with a pressure of ^ 50 MPa by inserting a crimping pin to a blank, then the crimping needle again removed and then the micro-bore is ground free by white machining and finally the over-rotated blank is sintered, characterized in that the hochdispersey'-alumina is pressed only in the radial direction of the future blank, while compression in the axial direction is completely prevented · 2 · pressing device for carrying out the method according to item 1, consisting essentially of a flexible mold with a support body, which is arranged in a recipient, characterized in that the flexible mold is designed as a press collar (2) whose axial openings by unn ^ giebige plugs are sealed, wherein ieich the edge of the stopper (4 x) projects beyond the outer contours of the Preßmanschette and Preßmanschette supported by a on the edges of the plug (4), perforated tube (3) is surrounded, and in that one of the plugs comprises a bore , by which the pressing needle (1) is fixed. - For this 1 sheet drawings -