IEC 61788-5:2000

INTERNATIONAL IEC
STANDARD
61788-5
First edition
2000-12
Superconductivity –
Part 5:
Matrix to superconductor volume ratio
measurement – Copper to superconductor volume
ratio of Cu/Nb-Ti composite superconductors
Supraconductivité –
Partie 5:
Mesure du rapport volumique matrice/supraconducteur –
Rapport volumique cuivre/supraconducteur des composites
supraconducteurs de Cu/Nb-Ti
Reference number
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INTERNATIONAL IEC
STANDARD
61788-5
First edition
2000-12
Superconductivity –
Part 5:
Matrix to superconductor volume ratio
measurement – Copper to superconductor volume
ratio of Cu/Nb-Ti composite superconductors
Supraconductivité –
Partie 5:
Mesure du rapport volumique matrice/supraconducteur –
Rapport volumique cuivre/supraconducteur des composites
supraconducteurs de Cu/Nb-Ti
 IEC 2000  Copyright - all rights reserved
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– 2 – 61788-5 © IEC:2000(E)
CONTENTS
Page
FOREWORD . 3
INTRODUCTION .4
Clause
1 Scope . 5
2 Normative references. 5
3 Terminology. 5
4 Principle . 6
5 Chemicals. 6
6 Apparatus . 6
7 Measurement procedure . 7
8 Calculation of results . 9
9 Precision and accuracy of the test method . 10
10 Test report . 10
Annex A (normative) Copper to superconductor volume ratio – copper mass method . 11
Annex B (informative) Specific mass of Nb-Ti . 12
Annex C (informative) Mechanical removal of insulating cover materials . 13
Annex D (informative) Second etch of specimen . 14

61788-5 © IEC:2000(E) – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
SUPERCONDUCTIVITY –
Part 5: Matrix to superconductor volume ratio measurement –
Copper to superconductor volume ratio of
Cu/Nb-Ti composite superconductors
FOREWORD
1) The IEC (International Electrotechnical Commission) is a world-wide organization for standardization
comprising all national electrotechnical committees (IEC National Committees). The object of the IEC is to
promote international cooperation on all questions concerning standardization in the electrical and electronic
fields. To this end and in addition to other activities, the IEC publishes International Standard. Their
preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt
with may participate in this preparatory work. International governmental and non-governmental organizations
liaising with the IEC also participate in this preparation. The IEC collaborates closely with the International
Organization for Standardization (ISO) in accordance with conditions determined by agreement between the
two organizations.
2) The formal decisions or agreements of the IEC on technical matters, prepared by technical committees on
which all the National Committees have a special interest therein are represented, express, as nearly as
possible, an international consensus of opinion on the subjects dealt with.
3) They have the form of recommendations for international use published in the form of standards, technical
specifications, technical reports or guides and they are accepted by the National Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standards and the corresponding national or regional standard shall be clearly
indicated in the latter.
5) The IEC provided no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
6) Attention is drawn to the possibility that some of the elements of this International Standard may be the
subject of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 61788-5 has been prepared by IEC technical committee 90:
Superconductivity.
The text of this standard is based on the following documents:
FDIS Report on voting
90/81/FDIS 90/87/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 3.
Annex A forms an integral part of this standard.
Annexes B, C and D are for information only.
The committee has decided that the contents of this publication will remain unchanged until
2005. At this date, the publication will be
• confirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
A bilingual version of this standard may be issued at a later date.

– 4 – 61788-5 © IEC:2000(E)
INTRODUCTION
The copper to superconductor volume ratio of composite superconductors is used mainly to
calculate the critical current density of superconducting wires. The test with the method given
in this International Standard may be used to provide part of the information needed to
determine the suitability of a specific superconductor. Moreover, this method is useful for
quality control, acceptance or research testing if the precautions given in this standard are
observed.
The test method given in this International Standard is based on the condition that the specific
mass of Nb-Ti is known. If the specific mass of Nb-Ti and/or the fraction of Nb barrier are
unknown, another method to determine the copper to superconductor volume ratio of
composite superconductors is described in annex A.

61788-5 © IEC:2000(E) – 5 –
SUPERCONDUCTIVITY –
Part 5: Matrix to superconductor volume ratio measurement –
Copper to superconductor volume ratio of
Cu/Nb-Ti composite superconductors
1 Scope
This part of IEC 61788 covers a test method for the determination of copper to super-
conductor volume ratio of Cu/Nb-Ti composite superconducting wire.
This test method is intended for use with Cu/Nb-Ti composite superconducting wires with a
2 2
cross-sectional area of 0,1 mm to 3 mm , a diameter of the Nb-Ti filament(s) of 2 µm to
200 µm, and a copper to superconductor volume ratio of 0,5 or more.
The Cu/Nb-Ti composite test conductor discussed in this method has a monolithic structure
with a round or rectangular cross-section. This test method is carried out by dissolving the
copper with nitric acid. Deviations from this test method that are allowed for routine tests and
other specific restrictions are given in this standard.
Cu/Nb-Ti conductors beyond the limits in the cross-sectional area, the filament diameter and
the copper to superconductor volume ratio could be measured with this present method with
an anticipated reduction in precision. Other, more specialized, specimen test geometries may
be more appropriate for conductors beyond the limits and have been omitted from this present
standard for simplicity and to retain precision.
The test method given in this standard is expected to apply to other superconducting
composite wires after some appropriate modifications.
2 Normative references
The following normative documents contain provisions which, through reference in this text,
constitute provisions of this part of IEC 61788. For dated references, subsequent
amendments to, or revisions of, any of these publications do not apply. However, parties to
agreements based on this part of IEC 61788 are encouraged to investigate the possibility of
applying the most recent edition of the normative document indicated below. For undated
references, the latest edition of the normative document referred to applies. Members of IEC
and ISO maintain registers of currently valid International Standards.
IEC 60050-815:2000, International Electrotechnical Vocabulary (IEV) – Part 815: Super-
conductivity
3 Terminology
For the purposes of this part of IEC 61788, the definitions given in IEC 60050-815 and the
following definition are applicable.
3.1
copper to superconductor volume ratio
the ratio of the area of the copper stabilizing material to the area without copper consisting of
Nb-Ti filaments and their Nb barriers.

– 6 – 61788-5 © IEC:2000(E)
4 Principle
The test method utilizes the nature of the Cu/Nb-Ti composite superconducting wire whereby
the copper dissolves in nitric acid solution but the Nb-Ti filaments and Nb barriers do not.
After measuring its mass, dip the specimen in the nitric acid solution to dissolve only the
copper.
Then measure the mass of the remaining Nb-Ti filaments and their Nb barriers.
Convert the ratio of masses to the ratio of volumes by dividing the respective masses of the
copper and filaments by the respective specific mass of the copper and filaments.
5 Chemicals
The following chemicals shall be prepared for sample preparation.
− Nitric acid solution consisting of nitric acid (a mass fraction of 50 % to 65 %
recommended) and distilled water
− Organic solvent
− Degreasing solvent
− Ethyl alcohol
− Distilled (pure) water
NOTE When nitric acid of more than a mass fraction of 65 % is used, the acid shall be diluted with distilled water
within the range of the above content.
6 Apparatus
Draft chamber
Balance
A balance should have a measuring resolution of 0,1 mg.
Dryer or drying oven
A dryer or a drying oven shall be used for evaporating moisture after washing the specimen.
− 300-ml beaker
− Watch-glass
− Plastic tweezers
− Filter papers
− Thermometer
Rubber gloves, protection spectacles and draft chamber
Rubber gloves and protection spectacles shall be used for protecting the human body from
the harmful acid liquid or fumes. The dissolution of the specimen shall be performed in a draft
chamber in order to protect the human body.

61788-5 © IEC:2000(E) – 7 –
7 Measurement procedure
7.1 Quantity of specimen
Take a specimen of around 1 g to 10 g in mass from the base test material.
7.2 Removal of insulating cover material
An appropriate organic solvent, which does not erode the copper, shall be used to remove
any insulating cover material of the specimen. Finally, it shall be visually checked that the
insulating cover material no longer remain
...