CS270622B1 - Method of sintering ferroelectric ceramic products - Google Patents

Abstract

The sintering method for firing piezoelectric elements with a high lead content used in the electrical industry prevents sintering of individual layers and allows easy separation of sintered products without the risk of their deterioration. Sintered products are backfilled and sprinkled with a powder material of the same chemical composition as the fired products, pre-fired at least to the firing temperature of the sintered products. The inner surface of the firing case can be coated with a coating of water-based minium suspension. The backfill material can be used many times.

Description

The invention relates to a process for sintering products and ferroelectric ceramics with a high lead content.

Piezo elements made of special ceramics with a high lead oxide content are extremely important for use in the electrical industry. They are used in various shapes, from miniature types to relatively solid elements. The scope of production places extraordinary demands on economical firing, especially of larger products. Advantageously, the firing of samples stacked in several layers can be used. The basic premise is that after firing it is possible to easily separate the fired products. Materials with a higher content of lead oxide are easily sintered and cannot be separated from each other after firing. According to the current elimination procedures, the fired elements in the housings were completely covered with common types of backfills. These backfills made of powder materials (mixture of oxides) can only be used for one firing of goods. After firing, the fired goods are very difficult to separate from the backfill and the integrity of the goods is often violated.

The disadvantages of the current technological method are solved by the method of sintering ferroelectric ceramic products with a high content of lead compounds, characterized in that the sintered products are backfilled and covered with powder material of chemical composition identical or similar to fired products, pre-fired at least to the firing temperature of sintered products. This method of sintering can be combined for special ceramic materials with the coating of the inner surface of the firing case with an aqueous suspension of minium.

The backfill is very easily obtained from sieved burrs of processed burns or by preparation from granules of PZT ceramics remaining from the previous technological operation. Before the first use, it is necessary to burn the backfill to sintering temperatures and higher. The advantage of this method of sintering is also that the stoichiometric composition of the fired goods is not disturbed by the possible vapor pressure of some volatile components. The great advantage is the fact that the backfill is reusable and that it can be very easily separated from the fired compacts.

The sintering method according to the invention can advantageously be used for separating fired goods stacked on top of one another in several layers. The laboriousness of cleaning after firing is significantly reduced.

The sintered granules can be used repeatedly, easily removed from the sample by wiping and used again for further backfilling and backfilling. To better ensure the required chemical composition of sintered objects, it is advantageous to backfill and cover the bottom and top layers with a backfill formed by a material of the same composition as the sintered objects.

The invention will be explained in more detail in the following example of use.

Example

The ceramic piezoelectric material based on Pb (Zr, Ti) O 2 modified with an admixture of strontium, iron, niobium, nickel, pressed in the shape of a disc, was placed in refractory concrete cases. The individual moldings were covered with a thin layer of sanding. The bulk material was obtained by sintering a powdered calcine of the same composition as the piezoelectric material at a temperature of 1300 ° C. Larger sintered units were sieved through a 100 mesh / c · ² sieve. For selected materials, the inner surface was wiped with an aqueous suspension of minium. The fired products were easily separable from each other. The used spill did not adversely affect the surface layers of the sintered goods. The spill was wiped with a spatula and used for subsequent firing.

CS 270 622 Bl. X repeated in subsequent shots? the backfill used did not affect the surface layers of the sintered goods. The goods were easily separable from each other. In all multiple firings, the goods exhibited the required piezoelectric properties required.

Claims (2)

A method of sintering ferroelectric ceramic products with a high content of lead compounds, characterized in that the sintered products are backfilled in the firing case and sprinkled with powdered material of chemical composition identical or similar to the fired products, fired at least to the firing temperature of sintered. products. 2. The method of sintering ferroelectric ceramic products according to item 1, characterized in that the inner surface of the firing case is coated with an aqueous suspension of minium.