Title of Invention

A NOVEL MAINTENANCE-FREE REFERENCE ELECTRODE FOR MULTIFARIOUS APPLICATIONS

Abstract A novel maintenance - free reference electrode for multifarious applications which comprises a rigid polyvinyl chloride tubular container characterised in that the said tubular container plugged at one end with a water cured cement plug so as to provide a bridge with the external medium, the surface of said cement plugged inside the said tublar pluge being provided with a layer of a semi solid paste (7) so as to provide hydroxyl ions to the half cell system, above the said layer of semisolid paste inside the container there is provided a tightly packed electrolytic manganese dioxide dry powder, the said tightly packed electrolyte inside the said container being provided with a co- centrically placed polished carbon rod (5) , the top external end of the said carbon rod being provided with an electrical lead, so as to develop intimate contact using sealed (1) as electrical lead, the top of the said container above the said packed electrolyte being provided a polyvinyl chloride bush (3) and epoxy sealing at the top (2).
Full Text /The present invention relates to a novel maintenance - free reference electrode for
multifarious applications.
It is now fairly well established that pipelines as well as structures buried
underground need continuous monitoring of the health condition whether cathodically
protected or not. Similarly steel reinforcements embedded in reinforced or pre-stressed
concrete bridges and structures need continuous monitoring because of their susceptibility
to corrosion. When such dynamically loaded structures are cathodically protected,
continuous monitoring of the half-cell potentials of embedded steel becomes a must. Such
a situation calls for a stable and maintenance -free reference electrode which can be
permanently embedded in concrete as close as possible to the embedded steel so as to
generate reliable data. This will facilitate efficient monitoring of cathodic protection as
well as the health condition of the bridges and structures and ultimately lead to enhanced
durability.
Hitherto known reference electrodes have certain drawbacks which limit their use
for specific situation particularly as embeddable electrodes.
Reference may be made to Reference electrodes theory and practice edited by
David J. G Ives and George J. Janz, Academic press New York (1961) wherein
construction and working of different electrodes such as calomel electrodes and
other mercury - mercurous salt electrodes, silver - silver halide electrodes, oxide
electrodes, sulphate electrodes etc, are discussed. These electrodes have the following
drawbacks.
Calomel electrodes and other mercury- mercurous electrodes are formed from
mercury and hence any leakage may lead to pollution hazard. Further, use of aqueous
solutions either potassium chloride or other salts require careful maintenance as well as
careful handling.
The process of making silver- silver halide electrodes is quite tedious as it
involves either electrodeposition or thermal decomposition. It is rather difficult to
achieve stability, sensitivity and reproducibility.
The process of making metal - metal oxide electrode is also laborious as it
involves using powdered metal - powered oxide in admixture. Some times aerial
oxidation is employed but it will have only a very small electro chemical capacity.
Anodic oxidation is also a difficult process.
In the case of Silver - Silver oxide electrode, it is rather difficult to secure
adequate reproducibility. Electrode potentials tend to be rather erratic.
The major draw back for metal - metal oxide electrodes is that nobility of metal
and stability of oxide do not run together. Hardness and polymorphism obstruct the
attainment of reproducible standard states.
Reference may also be made to Control of pipeline corrosion : edited by A .W Peabody
and published by National Association of corrosion Engineers, Texas, USA (1967) P 78,
where in use of copper / copper Sulphate reference electrode has been metioned. The
draw back of this electrode is the necessity for periodic replenishment of copper sulphate
crystals to maintain saturation.
ASTM C 876 also specifies the use of copper / copper sulphate as reference
electrode for measurement of rebar potential in concrete. The drawbacks are as follows:
The seepage of copper sulphate solution would contaminate the concrete and these copper
ions would influence the steel behaviour. Surface mounted reference electrodes are
subjected to ultraviolet radiation effect which considerably influences the measured
values and lead to errouneous data. (Frank j. Ansuini and J.R.Dimond, Factors affecting
the accuracy of reference electrodes, Materials performance, vol 13, 1994, p!4.).
Reference may be made to the Manganese dioxide electrode developed by Oskar
Klinghoffer of Concrete Inspection and Analysis and Department FORCE institute, Park
Alle 345 DK 2605, Brondby Denmark and reported. (Oskar Klinghoffer, Hans Arup, J.
Mietz - manganese dioxide reference electrodes for use in concrete, Eurocorr 97, Trend
heim, Sept. 1997). The main drawback of this system is that the metal thimble is made of
ainless steel which can in the long run undergo crevice and pitting corrosion in chloride
ivironment frequently met within concrete. Further, stainless steel by itself may
mtribute to the potential of the system and this might lead to erroneous interpretation.
Reference may be made to H.Dolli, V.S.Muralitharan and N.S.Rengaswamy
Embeddable Reference electrode for use in reinforced concrete, Proceedings of Tenth
National Congress on Corrosion Control 6-8 Sept .2000, Madurai pp 198-204 where in it
is reported that a solid graphite electrode depicts unstable potential - time behaviour and
unreliable passive - active behaviour.
Silver / silver chloride electrodes are photo sensitive according to Frank J.Ansuini
and J.R. Dimond [long term stability Testing of reference electrode for reinforced
concrete, corrosion /94 paper no.295 Texas, NACE, 1994]
Mercury / mercurous oxide electrode is unstable when embedded in concrete
[C.Dehaghasian, C.R Root and C.E Locke, Review of embeddable reference electrodes
for Portland cement concrete, paper No: 45 corrosion 81, NACE conference April 1981,
Ontario, Canada.]
The main object of the present invention is to provide a maintenance-free
reference electrode, which obviates the drawbacks as detailed above.
Another object of the present invention is to provide maintenance - free reference
electrode which is rugged, stable and durable.
Still another object of the present invention is to provide a maintenance - free reference
electrode which, can perform satisfactorily either in solution or in soil or in concrete
under ambient conditions. In the drawings accompanying this specification, figure 1 represents the schematic details of the newly developed maintenance - free reference electrode, figure 2 represents a typical cyclic voltammogramme of the developed maintenance - free reference electrode, figure 3 represents a typical cyclic voltammogramme of a commercially available Saturated Calomel Electrode, figure 4 represents the potential - current behaviour of mild steel with respect to the newly developed maintenance - free reference electrode in comparison with that of a saturated calomel electrode in 0.04 N - NaOH solution containing 1500 ppm of chloride, figure 5 represents the potential-time behaviour of mild steel rebar with respect to the newly developed maintenance free reference electrode in comparison with that of a saturated calomel electrode in sand medium containing 2000 ppm of chloride, figure 6 represents the potential - time behaviour of mild steel rebar with respect to the newly developed maintenance - free electrode in comparison with that of a saturated calomel electrode in sand medium mixed with 0.04N - NaOH Solution, figure 7 represents the potential-time behaviour of mild steel rebar with respect to the newly developed maintenance - free reference electrode in comparison with that of a saturated calomel electrode in concrete medium containing 50 ppm of chloride and figure 8 represents the potential - time behaviour of mild steel rebar with respect to the newly developed maintenance - free reference electrode in comparison with that of a hydroxyl ion reversible electrode when embedded in sand medium mixed with 0.04N - NaOH solution.
Accordingly the present invention provides a novel maintenance - free reference electrode for multifarious applications which comprises a rigid polyvinyl chloride tubular container characterised in that the said tubular container plugged at one end with a water cured cement plug so as to provide a bridge with the external medium, the surface of said cement plugged inside the said tublar pluge being provided with a layer of a semi solid paste (7) so as to provide hydroxyl ions to the half cell system, above the said layer of semisolid paste inside the container there is provided a tightly packed electrolytic manganese dioxide dry powder, the said tightly packed electrolyte inside the said container being provided with a co- centrically placed polished carbon rod (5) , the top external end of the said carbon rod being provided with an electrical lead, so as to develop intimate contact using sealed (1) as electrical lead, the top of the said container above the said packed electrolyte being provided a polyvinyl chloride bush (3) and epoxy sealing at the top (2).

In an embodiment of the present invention, the newly developed reference electrode is quite rugged and can be used in any orientation.
In another embodiment of the present invention, the newly developed reference electrode can be permanently kept embedded in soil or concrete.
In yet another embodiment of the present invention, the newly developed reference electrode offers minimum ohmic drop in potential measurements.
The constructional features are shown in figure 1. A rigid type polyvinyl chloride tubular container open at both ends and measuring internal diameter in the range 10mm to 50mm and length in the range 50mm to 150mm is taken. Cement mortar containing one part of ordinary Portland cement either 43 or 53 grade as per IS: 8112 / IS: 12269 is dry mixed with zero to two parts of salt free river sand conforming to IS: 383. Deionised water in the ratio 30% to 50 % by weight of cement is thoroughly mixed with the cement mixture to form a workable paste. The paste is then packed to a height of 10mm to 25
7 mm at one end of the polyvinyl chloride container to form a plug. The plug is air - dried
for 24 hours under 100% RH and then cured in deionised water for a period of 72 hours
to 168 hours. After water curing the plug is air dried for 24 hours. One part of calcium
oxide (L.R. grade) and two parts of sodium hydroxide pellets (L.R. grade) are intimately
ground to form a paste and applied uniformly over the cement plug inside the container to
a thickness of 1mm to 5mm. This paste is allowed to set for a period of 24 hours to 72
hours. Dry electrolytic manganese dioxide powder is then packed inside the container to a
height of 5mm to 15mm. Carbon rod varying in diameter from 4mm to 10mm and
varying in length from 50mm to 150mm so as to have a protruding length of 10 to 15mm
over the top of the container is emery polished and centrally embedded inside the
container and then the annular space is tightly packed with electrolytically pure dry
manganese dioxide powder leaving only the top lOtnni to 30mrn which is then tightly
plugged with a polyvinyl chloride bush.
Electrical ^grade copper wire 14 to 18 gauge thick and of length 30mm to 60mm is then
wound around a 1mm grove formed at the top end of carbon rod. The protruding portion
as well as the top of the bush is then sealed with epoxy putty leaving only the shielded
copper lead wire.
While embedding the newly developed reference electrode in concrete or soil the
free end of the lead wire is taken out side and connected to the potential monitoring
system whenever needed. If necessary additional length of lead wire may be used.
The newly developed maintenance - free reference electrode has the following novel
features.
8
1. The carbon rod used in the system is highly conducting and at the same time it is
chemically stable under the environmental changes and temperature changes that
could occur under ambient field conditions.
2. The carbon rod obtained from old discharged dry cell batteries can be polished and
reused thereby facilitating recycling of a scarce item.
3. Use of crystals of sodium hydroxide and Calcium oxide ensures long-term supply of
hydroxyl ions. This is in addition to the supply of hydroxyl ions from the cement
plug.
4. The cement plug provided at one end not only acts as a conducting plug but also
makes the electrode as reliable as saturated calomel electrode.
5. Use of polyvinyl chloride rigid type container provides an inert container with
proven long-term durability, as conventionally, concealed electrical wiring is taken
through rigid PVC pipes laid at the time of casting of concrete.
6. The system has got the adaptability of being installed under any orientation.
7. Combination of the solid carbon rod and dry manganese dioxide powder packing
makes the system maintenance-free.
The following examples are given by way of illustrations of the present invention and
should not be construed to limit the scope of the present invention.
EXAMPLE I
Construction of a newly developed maintenance - free reference electrode.
A 16mm internal diameter and 50mm long rigid type polyvinyl chloride tubular
container was taken. 43 grade ordinary Portland cement was mixed with 30%
deionised water by weight of cement to form a workable paste. The paste was then
packed to a height of 10mm at one end of the tubular container to a form a plug. The
plug was air cured for 24 hours under 100% RH and then cured in deionised water for
168 hours. After water curing, the cement plug was air dried for 24 hours. One part of
calcium oxide (L.R. grade) and two parts of sodium hydroxide pellets (L.R. grade)
were intimately ground to form a paste and applied uniformly over the cement plug
inside the container to a thickness of 5mm. This paste was allowed to set for a period
of 24 hours. Dry electrolytic manganese dioxide powder was then packed inside the
container to a height of 10mm. Carbon rod 4mm in diameter and 50mm in length was
emery polished (zero / zero) and centrally embedded inside the container and then the
>
annular space was tightly packed with dry electrolytically pure manganese dioxide
powder leaving only the top 10mm which was then plugged with a polyvinyl chloride
bush. 14 gauge electrical grade copper wire (30cm long) was then wound around a
1mm size grove formed at the top end of the carbon rod. The protruding portion as
well as the top of the bush was then sealed with epoxy putty leaving only the shielded
copper lead wire.
Four such reference electrodes were constructed and used in the succeeding
examples.
EXAMPLE II
Reversibility characteristics:
This test is carried out on a reference electrode to check the reversibility and
reproducibility of the electrode potentials. It is carried out on a three-electrode
electrochemical cell. The developed maintenance free - electrode is used as a working
electrode.
Bioanalytical system (BAS 100A) is used for small amplitude cyclic voltametry.
The amplitude of potential is ±15 mV and the sweeprate1 mV/sec. The resultant
potential - current curve is recorded. The zero current crossing potentials (zccp) for the
forward and backward scans are noted. The difference in potential values is the measure
of reversibility. For a perfect reference electrode system, A E - 0 as the sweep rate
tends to zero. Figure 2 represents a typical cyclic voltammogramme of the developed
maintenance - free reference electrode. Figure 3 represents a typical cyclic
voltammogramme of a commercially available calomel electrode.
Working electrode :- Developed maintenance - free reference electrode.
Counter electrode : - 2.5x2.5 cm platinum foil.
Reference electrode :- Saturated calomel electrode (Commercially available).
Electrolyte :- 0.04N - NaOH Solution.
ELECTRODE A E (mV Vs SCE)
Commercially available Calomel electrode 1.23
Newly developed maintenance- free electrode 1.42
It can be seen that the newly developed maintenance - free reference electrode
has the desirable reversibility characteristics when compared to calomel electrode.
EXAMPLE HI
Temperature co-efficient:
Variation of electrode potential with respect to temperature in the range 27°C to 40°C
was studied using a thermostatic water bath.
Table 2 presents the data on variation of potential of the developed maintenance -
free reference electrode in comparison to a saturated calomel electrode. It can be seen that
the potential remains stable with respect to the temperature range studied with an
insignificant variation of less than 1%. The variation in potential between different
maintenance-free reference electrodes also remains within a permissible limit of ± 4 mV.
Thus it is shown that the developed maintenance - free reference electrode has the
required stability in the temperature range 27° C to 40° C.
Working electrode :- Developed maintenance - free reference electrode.
Reference electrode :- Saturated calomel electrode (Commercially available).
(Table Removed)e.
Dynamic cathodic polarisation studies were carried out using VOLTA LAB -21 electro
chemical Laboratory system. PGP-201 POTENTIO STAT / GALVANOSTAT.
Open circuit potential of the mild steel specimen was monitored over a period of
60 minutes. The passive-active behaviour was noted. Subsequently the mild steel
specimen was cathodically polarised at a sweep rate of ImV/sec up to a maximum
cathodic over potential of lOOOmV with respect to open circuit potential. The resultant
potential - current behaviour was recorded. In another set of experiments the newly
developed maintenance - free reference electrode was used as reference electrode in place
of calomel electrode and the above study was repeated.
Figure 4 depicts the potential-current behaviour. It can be seen that the same
trend is maintained in both the experiments.
It is thus shown that the behaviour of the newly developed maintenance - free
reference electrode is similar to that of standard saturated calomel electrode in 0.04NNaOH
solution containing ISOOppm of chloride.
EXAMPLE -V
Electrode Behaviour in sand medium mixed with 2000 ppm chloride solution
[Active - Neutral medium]
Working electrode :- Twisted mild steel rebars.
Reference electrodes:- Saturated calomel electrode (Commercially available) and
Newly developed maintenance - free reference electrode.
Electrolyte :- 2000 ppm chloride solution.
Washed and dried river sand was mixed with 2000 ppm chloride solution so as to
make a workable mixture. This semi-solid mixture was packed tightly in a non- metallic
container of size 20x20x1 Ocm. Two numbers of cold twisted mild steel reinforcements
(8mm dia 10cm long) were derusted and degreased. Electrical leads were taken from one
end. The reinforcement rods were embedded at a depth of 8cm from the top surface. The
spacing between the rods was maintained at 8cm. A saturated calomel electrode as well
as the newly developed maintenance - free reference electrode was surface - mounted at
the same location with a spacing of 2cm.
The open circuit potential of the embedded steel rebars (which were externally
short circuited) was monitored over a period of 60 minutes. Subsequently a pure
magnesium anode of size 5x3cm was placed on the top surface and externally short
circuited with the rebar terminals. The potential of the rebars got shifted in the cathodic
direction and this polarised potential was monitored over a period of 180 minutes.
Subsequently the anode terminal was disconnected from rebar terminal and the decay in
potential was recorded over a period of 60 minutes.
Figure 5 depicts the comparative behaviour of the saturated calomel electrode and
the newly developed electrode. It can be seen that the potential- time behaviour of the
rebars with respect to the newly developed maintenance - free reference electrode is akin
to that of the standard calomel electrode. The difference in potential values remains more
or less constant under the three conditions viz., open circuit potential, polarised potential
and decay potential.
15
Thus, it is shown that the behaviour of the newly developed maintenance - free
reference electrode is similar to that of a standard saturated calomel electrode in the sand
medium mixed with 2000 ppm chloride solution.
EXAMPLE -VI
Electrode Behaviour in sand medium mixed with 0.04N-NaOH solution
[Passive - Alkaline medium]
Working electrode :-Twisted mild steel rebars (8 mm dia 100 mm long).
Reference electrodes:- Saturated calomel electrode (Commercially available) and
Newly developed maintenance - free reference electrode.
Electrolyte :- 0.04N - NaOH Solution mixed with river sand.
Washed and dried river sand was mixed with 0.04N-NaOH solution so as to make a
workable' mixture. This semi- solid mixture was packed tightly in a non- metallic
container of size 20x20x1 Ocm. Two numbers of cold twisted mild steel reinforcements
(8mm dia 10cm long) were derusted and degreased. Electrical leads were taken from one
end. The reinforcement rods were embedded at a depth of 8cm from the top surface. The
spacing between the rods was maintained at 8cm. A saturated calomel electrode as well
as the newly developed maintenance - free reference electrode was surface mounted at
the same location with a spacing of 2cm.
The open circuit potential of the embedded steel rebars (which were externally
short circuited) was monitored over a period of 60 minutes. Subsequently a pure
magnesium anode of size 5x3cm was placed on the top surface and externally short
16
circuited with the rebar terminals. The potential of the rebars got shifted in the cathodic
direction and this polarised potential was monitored over a period of 240 minutes.
Subsequently the anode terminal was disconnected from rebar terminal and the decay in
potential was recorded over a period of 60 minutes.
Figure 6 depicts the comparative behaviour of the saturated calomel electrode and
the newly developed maintenance - free reference electrode. It can be seen that the
potential-time behaviour of the rebars with respect to the newly developed maintenance -
free reference electrode is akin to that of the standard saturated calomel electrode. The
difference in potential values remains more or less constant under the three conditions viz
open circuit potential, polarised potential and decay potential.
Thus, it is shown that the behaviour of the newly developed maintenance - free reference
electrode is similar to that of a standard saturated calomel electrode in the sand medium
mixed with 0.04N-NaOH solution.
EXAMPLE VII
Electrode Behaviour in concrete medium containing 50 ppm of chloride.
Working electrode : - Embedded mild steel rebar.
Reference electrodes :- Saturated calomel electrode (Commercially available)and
Newly developed maintenance - free reference electrode.
Electrolyte :- Concrete containing 50 ppm chloride.
A rectangular concrete prism of size 20x1 Ox 10cm was cast with a derusted and
degreased mild steel reinforcement of size 8mm dia 10.5cm long embedded with a clear
cover of 6cm from the top surface. Electrical lead was taken from one end of the same
reinforcement before embedment. A saturated calomel electrode as well as the newly
developed maintenance - free reference electrode was surface mounted at the same
location with spacing of 2 cm.
The open circuit potential of the embedded steel rebar was monitored over a
period of 60 minutes. Subsequently a pure magnesium anode of size ScmxScm was
placed on the top surface and externally short circuited with the rebar terminals. The
potential of the rebar got shifted in the cathodic direction and this polarised potential was
monitored over a period of 240 minutes. Subsequently the anode terminal was
disconnected from rebar terminal and the decay in potential was recorded over a period of
60 minutes. Figure 7 depicts the comparative behaviour of the saturated calomel
electrode and the newly developed maintenance - free reference electrode. It can be seen
that the potential-time behaviour of the rebar with respect to developed electrode is akin
to that with respect to the saturated calomel electrode. The difference in potential values
remains more or less constant under the three conditions Viz open circuit potential,
polarised potential and decay potential.
Thus it is shown that the behaviour of the newly developed maintenance - free
reference electrode is similar to that of a standard saturated calomel electrode in the
concrete medium containing 50 ppm of chloride.
EXAMPLE VIH
Behaviour of embedded electrode in sand medium mixed with 0.04N-NaOH.
Working electrode :- Twisted mild steel rebar.
Reference electrodes :- Hydroxyl ion reversible electrode and
Newly developed maintenance - free reference electrode.
Electrolyte :- 0.04N-NaOH mixed with sand medium.
Washed and dried river sand was mixed with 0.04N-NaOH solution so as to make a
workable mixture. This semi- solid mixture was packed tightly in a non-metallic
container of size of 20x20x1 OCm. Two numbers of cold twisted mild steel reinforcements
(8mm dia lOCm long) were derusted and degieassed. Electrical leads were taken from
one end. The reinforcement rods were embedded at a depth of 8cm from the top surface.
The spacing between the rods was maintained at 8 cm.
A hydroxyl ion reversible electrode (HRE) as well as the newly developed
maintenance - free reference electrode (NDE) were embedded centrally in between the
embedded reinforcement rods at the same depth of 8cm from the top surface. The open
circuit potentials of the embedded steel bars (which were externally short circuited) were
monitored with respect to the two embedded electrodes over a period of 60 minutes.
Subsequently a pure magnesium anode of size 5x3Cm was placed on the top surface and
externally short circuited with the rebar terminals. The potentials of the rebars got shifted
in the cathodic direction and this polarised potential was monitored over a period of 30
minutes. Subsequently anode terminal was disconnected from rebar terminal. And the
decay in potential with respect to the two embedded electrodes was recorded over a
period of 50 minutes. Figure 8 depicts the comparative behaviour of the embedded
rebars with respect to the embedded hydroxyl ion reversible electrode and the newly
developed maintenance - free reference electrode. It can be seen that the potential-time
behaviour of the rebars with respect to the newly developed maintenance - free reference
electrode is akin to that of a hydroxyl ion reversible electrode. The difference in potential
values remains more or less constant under the three conditions viz open circuit potential,
polarised potential and decay potential.
Thus it is shown that the behaviour of the newly developed maintenance - free
reference electrode is similar to that of a proven hydroxyl ion reversible electrode when
embedded in the sand medium mixed with 0.04N-NaOH solution.
The main advantages of the present invention are
(1) The developed maintenance - free reference electrode is rugged in construction
and can be used in any orientation.
(2) The developed reference electrode is maintenance - free and therefore can be
permanently kept embedded in concrete or soil.





We claim;
1. A novel maintenance - free reference electrode for multifarious applications which comprises a rigid polyvinyl chloride tubular container characterised in that the said tubular container plugged at one end with a water cured cement plug so as to provide a bridge with the external medium, the surface of said cement plugged inside the said tublar pluge being provided with a layer of a semi solid paste (7) so as to provide hydroxyl ions to the half cell system, above the said layer of semisolid paste inside the container there is provided a tightly packed electrolytic manganese dioxide dry powder, the said tightly packed electrolyte inside the said container being provided with a co- centrically placed polished carbon rod (5), the top external end of the said carbon rod being provided with an electrical lead, so as to develop intimate contact using sealed (1) as electrical lead, the top of the said container above the said packed electrolyte being provided a polyvinyl chloride bush (3) and epoxy sealing at the top (2).
2. A novel electrode as claimed in claim 1 wherein the water cured cement plug is prepared by 43 grade ordinary Portland cement with 30 % deionised water followed by air curing and water curing for 24 hrs. and 168 hrs. respectively.
3. A novel electrode as claimed in claims 1 & 2 wherein the semisolid paste is prepared by calcium oxide powder and sodium hydroxide pellets applied over the cement plug inside the container to ensure adequate supply of hydroxyl ions.
4. A novel electrode as claimed in claims 1 & 2 wherein the semisolid paste use is consisting of CaO & NaOH at 1 : 2 ratio.
5. A novel maintenance - free reference electrode for multifarious applications, substantially as here in described with reference to the examples and drawings accompanying this specification.

Documents:

775-DEL-2002-Abstract-(31-12-2010).pdf

775-del-2002-abstract.pdf

775-DEL-2002-Claims-(31-12-2010).pdf

775-del-2002-claims.pdf

775-DEL-2002-Correspondence-Others-(31-12-2010).pdf

775-del-2002-correspondence-others.pdf

775-DEL-2002-Description (Complete)-(31-12-2010).pdf

775-del-2002-description (complete).pdf

775-del-2002-drawings.pdf

775-del-2002-form-1.pdf

775-del-2002-form-18.pdf

775-del-2002-form-2.pdf

775-del-2002-form-3.pdf


Patent Number 249266
Indian Patent Application Number 775/DEL/2002
PG Journal Number 42/2011
Publication Date 21-Oct-2011
Grant Date 13-Oct-2011
Date of Filing 25-Jul-2002
Name of Patentee COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH
Applicant Address RAFI MARG, NEW DELHI-110 001,INDIA
Inventors:
# Inventor's Name Inventor's Address
1 VARAGUR SWAMINATHAN MURALIDHRAN CENTRAL ELECTROCHEMICAL RESEARCH INSTITUTE,KARAIKUDI,INDIA
2 HIRUDAYASAMY DOLLI CENTRAL ELECTROCHEMICAL RESEARCH INSTITUTE,KARAIKUDI,INDIA
3 NERUR SANKARANARAYANAN RENGASWAMY CENTRAL ELECTROCHEMICAL RESEARCH INSTITUTE,KARAIKUDI,INDIA
4 MEENAKSHI SUNDARAM RAGHAVAN CENTRAL ELECTROCHEMICAL RESEARCH INSTITUTE,KARAIKUDI,INDIA
PCT International Classification Number G01N 27/00
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA