DD294932A5 - METHOD FOR THE FUEL-CLASS FEEDING OF PARTS OF OXID AND NON-OXIDE CERAMICS - Google Patents

Abstract

The invention relates to a process for materially joining parts of oxidic and non-oxidic ceramics. According to the invention, a paste-like intermediate layer of alkali-water glass and a powder of one or more substances having glassy-crystalline structures is applied to one of the previously roughened surfaces, and then, after the parts have been joined, the compound is subjected to a multi-stage heat treatment at temperatures up to 300 ° C. The process according to the invention makes it possible to produce joining compounds with relatively simple means and low energy expenditure, which can be thermally stressed up to temperatures of 700 to 800 ° C. {Joining method, integral; Ceramic parts, oxidic, non-oxidic; Intermediate layer; Alkali water glass; Powder mixture; Fuel additive; glassy-crystalline structures; multi-stage heat treatment}

Description

Field of application of the invention

The invention relates to a method for materially joining parts of oxidic and non-oxide ceramics. It can be used to join parts with small or large joining surfaces as well as different geometry.

Characteristic of the known state of the art A number of methods for cohesive joining of oxide or non-oxide ceramics with each other has the Connect via intermediate layers to the content. So comes z. For example, in JP-PS 62-128945 a mixture of 10 to 90 wt .-% La ₂ O ₃ , 20 to 85 wt .-% Dy ₂ O ₃ , 5 to 60 wt .-% Y ₂ O ₃ , 5 bis

60% by weight of Al ₂ O ₃ , 5 to 45% by weight of BeO and 5 to 35% by weight of B ₂ O ₃ are used.

According to DE-AS 19 23138 an intermediate layer of 49 wt .-% Al ₂ O ₃ , 45 wt .-% CaO and θ Ma .-% MgO and JP-PS 63-08270

a layer of 15 to 50 mass% Al ₂ O ₃ , 15 to 50 mass% SiO ₂ and 25 to 50 mass% Y ₂ O _{3 is} used.

As a composition for a binding intermediate layer, a mixture of 90% by weight of Cu ₂ O is also known from JP-PS 62-148371,

5% by weight Al ₂ O ₃ and 5% by mass Si ₃ N ₄ possible.

In JP-PS 62-265183, as an agent suitable for bonding nitride ceramics, a fused or

Sintered mass of 20 to 50% CaO ₁ 30 to 55% SiO ₂ , 5 to 20% Al ₂ O ₃ and 3 to 12% TiO ₂ used. Furthermore, according to JP-PS 62-46968 layers of Al ₂ O ₃ are connected to each other by means of suitable glass solders. Also

Oxynitride glasses can be used, as documented in JP-PS 62-128975, for joining ceramics. The known methods of bonding ceramics by means of intermediate layers of oxide mixtures and by means of amorphous

or crystallizing glass solders have the disadvantage that for cohesive joining usually relatively high

Temperatures are required or that, if the working temperatures are not so high, the chemical Resistance of the connecting layers is low. The application of organic adhesives, such as those in JP-PS 60-86103,60-155567 and 59-137376 are described as binders for ceramics, although the production of the Joining compounds requires much lower temperatures than the compounds with oxide mixtures or glass solders as Interlayers, regardless of whether inorganic fillers are components of the intermediate layer or not, only

to compounds with low thermal resistance.

Methods to add ceramics by means of diffusion welding, linen require high equipment complexity, as is often the case High vacuum and high temperatures. Furthermore, when connecting ceramics by hot pressing, as for example

is described in WO 8603735 for carbide and nitride, also very high temperatures required.

Object of the invention The aim of the invention is to reduce the technical equipment and energy costs when joining. Explanation of the essence of the invention The invention is based on the object, a method for cohesive joining of parts of oxidic and

to develop non-oxide ceramics, which allows the joining of the parts under normal atmosphere or an inert gas without adverse thermal influence on the parts to be joined.

According to the invention this object is achieved by a method in which the parts via an intermediate layer and a Heat treatment process are connected together, solved by applying to one of the previously roughened Joining surfaces a pasty intermediate layer of alkali water glass and a powder of one or more substances with

glassy-crystalline structure is applied and then after the joining of the parts, the compound is subjected to a multi-stage heat treatment at temperatures up to 300 ⁰ C.

Advantageously, the joining surfaces of the parts to be joined before the application of the intermediate layer by a Grinding process roughened. By applying the method according to the invention can be compounds of parts of oxidic and

non-oxidic ceramists, using relatively simple technology with low energy input, which can be up to

Temperatures of 700 to 800 ⁰ C are thermally stable. Ausführungsbeisplel In three embodiments below, the inventive method will be explained in more detail. example 1 Two rods of an Al ₂ O ₃ ceramic are roughened at the joint surfaces by means of coarse-grained abrasive paper. Subsequently

The bars are cleaned for 15 minutes with acetone in an ultrasonic bath and dried in air. Made of potassium water glass and a

Powder with a grain size of <90 μm from the glass-ceramic jet produces a highly viscous but spreadable paste which can be used as a powder

thin layer is applied to the joint surface of a part.

Thereafter, the other part with its joining surface is placed on it, and it is a 20-hour curing at room temperature

under a joint pressure of 0.01 MPa. Thereupon, a first heat treatment at 150 to 16O ⁰ C (two hours) and two further heat treatments at 200 ⁰ C and 300 T, also each two hours performed. The heat treatments are carried out under normal atmosphere. Thereafter, the furnace is cooled. The result is a compound which is thermally stable up to 800 ⁰ C.

Example 2

Two round disks made of an Al ₂ O ₃ ceramic are pretreated as in Example 1. From potassium water glass and a powder from the glass ceramic llmavit® 40 a highly viscous, but spreadable paste is produced, which is applied to the joint surface of a part. Subsequently, the joining surfaces are brought together. After 20 hours of curing at room temperature and a joining pressure of 0.01 MPa, the same heat treatment under normal atmosphere as described in Example 1.

Example 3 Two round disks made of AIN ceramic are pretreated as in Example 1. Made of potassium water glass and a powder

The glass ceramic jenit is a highly viscous, but spreadable paste produced, which is applied to a joining surface. The further procedure is identical to that described in Examples 1 and 2. Deviating from this is a

Heat treatment under inert gas to prevent oxidation of the AIN ceramic. The resulting compound is stable up to 700 ⁰ C.

Claims (2)

1. A method for the cohesive joining of parts of oxide and non-oxide ceramics, wherein the parts are interconnected via an intermediate layer and by a heat treatment process, characterized in that on one of the previously roughened joining surfaces, a pasty intermediate layer of alkali water glass and a powder of one or more After applying the parts, the compound is subjected to a menrstuf igen heat treatment at temperatures up to 300 ⁰ C is then applied substances with glassy-crystalline structure. 2. A method for materially joining parts of oxide and non-oxide ceramics according to claim 1, characterized in that the joining surfaces of the parts to be joined are subjected to a grinding operation prior to the application of the intermediate layer.