Electricity: measuring and testing – Electrolyte properties – Using a conductivity determining device
Patent
1994-12-07
1996-02-27
Wieder, Kenneth A.
Electricity: measuring and testing
Electrolyte properties
Using a conductivity determining device
324450, 204422, G01N 2742
Patent
active
054951763
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a cell for measuring electrical conductivity of liquid having conductivity of 100 k .OMEGA..cm or less, and in particular to a cell for measuring conductivity, which can be used at high temperature or high pressure conditions and in corrosive substances by adopting ceramics for container and electrodes.
BACKGROUND TECHNIQUE
In the past, a cell as shown in FIG. 1 has been used for measuring electrical conductivity of liquid having conductivity of 100 k .OMEGA..cm or less.
FIG. 1(a) shows a cell, which comprises a glass container 2 with side tubes 4 protruding inwardly on the sides thereof, electrodes 1 made of precious metal such as platinum and supported on tips of the side tubes, and lead wires 5 passed through the side tubes.
Specimen liquid 6 is placed in the container and a stopper 3 is provided to close it, and electric current is applied across the electrodes to measure electrical conductivity.
FIG. 1(b) shows a filling type cell for laboratory use. On both ends of an oblong glass container 2, electrodes 1 are disposed, and specimen liquid is filled through and discharged from two side tubes 7a and 7b extending upward. By applying electric current across the electrodes on the two ends of the glass container 2, electrical conductivity is measured.
FIG. 1(c) shows an immersion type cell. A glass container 2 has a small opening. By immersing the container in specimen liquid, the liquid enters through the opening. Electrical conductivity is measured by applying electric current across the electrodes.
However, each of the conventional type cells has a problem in corrosion resistant property, particularly against alkali, because glass is used for the container. Also, there are problems with mechanical strength and corrosion resistant property under high temperature and high pressure conditions. If metal other than precious metal is used for electrodes, problems arise with corrosion resistant property. The use of precious metal leads to the increase of cost because Pt, Au, etc. are expensive.
It is an object of the present invention to provide a cell, which has high corrosion resistant property and can be used under strong acid or strong alkaline conditions.
It is another object of the present invention to provide a cell, which has high mechanical strength and is suitable for the use under high pressure and high temperature conditions.
It is still another object of the present invention to provide a cell, which can be produced at lower cost.
DISCLOSURE OF THE INVENTION
To attain the above objects, the cell for measuring conductivity according to the present invention uses ceramics with high corrosion resistant property for container and electrodes, whereby the container is made of insulating ceramics, and electrodes are made of conductive ceramics having resistance value of several k .OMEGA..cm or less.
As ceramic materials for electrodes, there are carbides such as TiC, ZrC, VC, TaC, Mo.sub.2 C, WC, SiC, etc., nitrides such as TiN, ZrN, VN, NbN, TaN, Cr.sub.2 N, etc., carbonitride Ti(C-N), borides such as TiB.sub.2, ZrB.sub.2, NbB.sub.2, TaB.sub.2, CrB.sub.2, MoB, etc., silicides such as TiSi.sub.2, ZrSi.sub.2, NbSi.sub.2, CrSi.sub.2, MoSi.sub.2, WSi.sub.2, etc., single conductive ceramic such as TiO.sub.2-x, conductive material such as complex ceramics containing two or more types of these substances, oxynitrides type sialon (a series of substances containing elements of Si-Al-O-N), and complex ceramics with Al.sub.2 O.sub.3, ZrO.sub.2, etc.
As the ceramic materials to be used for the container, there are various types of insulating ceramics such as Si.sub.3 N.sub.4, .alpha.-sialon(Y.sub.x (Si,Al).sub.12 (O,N).sub.16), .beta.-sialon (Si.sub.6-z Al.sub.Z.N.sub.8-z O.sub.z), ZrO.sub.2, Al.sub.2 O.sub.3, mullite, spinel, SiC, etc.
With the materials selected from these substances, a cell in cylindrical shape is prepared as shown in FIG. 2. In FIG. 2, the reference numeral 1 represents an electrode made of conductive ceramics, 2 is a container made of in
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patent: 5025219 (1991-06-01), Gaspard
patent: 5151660 (1992-09-01), Powers et al.
patent: 5186806 (1993-02-01), Clark et al.
patent: 5187444 (1993-02-01), Kumada et al.
Nakayama Susumu
Shiranita Akira
Do Diep
Shinagawa Refractories Co. Ltd.
Wieder Kenneth A.
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