CS213889B1 - A method for producing a ceramic diaphragm with determined absorbency for reference electrodes - Google Patents

Abstract

Method of manufacturing a ceramic membrane with a specified absorbency for reference electrodes in the range of 3.4 to 17.1% by weight and a specified discharge of an internal reference solution to obtain the required optimum value of this discharge for any type of ion-selective electrode during its application, which is achieved by heating the alumina pressings to a temperature corresponding to the relationship t « -Σ-Ζ-ΐΕ—, where t 3 is the temperature in °C, 9 z * absorbency in % by weight, k = S7.5 and q » - 0.04.

Description

BACKGROUND OF THE INVENTION The present invention relates to a process for producing a ceramic membrane of alumina and having a homogeneously distributed porosity and having a determined water absorption in the range of 3 * 4 to 17 * 1% by weight for reference electrodes.

The application of potentiometric analytical methods requires that the reference electrodes be of high quality. Their quality is determined both by their internal arrangement and, in particular, by the quality of the fluid connection between the inner solution of the reference electrode and the outer measured solution. In the application of some types of ion-selective electrodes, it is especially necessary that the internal electrolyte of the reference electrode be contaminated with as little as possible, that is, its leakage is as small as possible. Depending on the type of ion-selective electrode used, it is expedient for this discharge to have an optimum value for each type. The effluent is directly in dependence on the absorbency of the ceramic membrane of the reference electrode. Until now, these membranes with suitable effluents have been obtained by selection, which is not economically advantageous. It is much more advantageous to provide a ceramic membrane with a predetermined water absorption and hence an outlet.

It was therefore an object of the present invention to provide a process for manufacturing ceramic membranes for reference electrodes that would allow the membranes to be provided with a specific absorbency and hence the desired effluent.

The object is achieved by the invention of a method of producing a ceramic membrane with a predetermined absorbency and homogeneously distributed alumina porosity in the absorbency range of 3.4 to 17% by weight, characterized in that the compressed alumina is subjected to heating to a temperature. corresponding to ¹ t. · -ϊ - * -, where t - temperature in ° C x = water absorption in% of mass. k = 7,5 7.5

Q ^s - 0 * 04

Specific examples of the production of ceramic mentorants are given below.

Example 1

To achieve a water absorption of 17 * 1 wt. The aluminum oxide of 99.999 purity for the synthesis of single crystals was pressed into platelets at a pressure of 70 MPa. In accordance with the invention, the plates were subjected to heating to 1250 ° C with one hour holding time. The resulting material had the required wicking capacity of 17 * 1% by weight, and the plates cut with rollers ® 1.5 mm and 6 mm further were sealed into a glass tube and this blank was used to construct the kaloael electrode. The electrode had these properties;

discharge of saturated potassium chloride 50 yul / hed electrical resistance 1 kQ

Example 2

To achieve an absorbency of 14.0 wt. The same procedure was followed except that the temperature used was 1350 ° C. The properties of the calemel electrode with this meabrene were as follows;

discharge of saturated potassium chloride 4 * 5 yUl / h electrical resistance 5 kQ

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Example3

To achieve the required water absorption, 9.9 wt. The procedure was as in the previous examples, except that the temperature used was 1450 ° C. Kaleael electrode with this

The membrane had the following characteristics:

discharge of saturated potassium chloride 0.8 yol / h electrical response 35 kQ

Example 4

A 3.5% w / w absorbency was desired. Therefore, in an otherwise identical procedure, a temperature of 1600 ° C was used. The Khlomel electrode with this membrane had the following characteristics: saturated potassium chloride outlet 0.5 yul / h electrical resistance 100 kQ

Claims (1)

SUBJECT OF THE INVENTION A process for the manufacture of a ceramic membrane having a determined water absorption for an electrode reference in the range of 3.4 to 17.1 wt. and homogeneously distributed alumina porosity, characterized in that the compressed alumina is subjected to heating to a temperature corresponding to the relation x - to t '----- »q where t = temperature in ° C x - water absorption in% wt.