Superconductivity - Part 5: Matrix to superconductor volume ratio measurement - Copper to superconductor volume ratio of Cu/Nb-Ti composite superconducting wires

IEC 61788-5:2013 covers a test method for the determination of copper to superconductor volume ratio of Cu/Nb-Ti composite superconducting wires. This test method and the alternate method in Annex are intended for use with Cu/Nb-Ti composite superconducting wires with a cross-sectional area of 0,1 mm2 to 3 mm2, a diameter of the Nb-Ti filament(s) of 2 micrometers to 200 micrometers, 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 composite superconducting wires 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 of uncertainty. 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 low uncertainty. The test method given in this standard is expected to apply to other superconducting composite wires after some appropriate modifications. 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. This second edition cancels and replaces the first edition published in 2000. It constitutes a technical revision. The main revisions are the addition of two new annexes, 'Uncertainty considerations' (Annex E) and 'Uncertainty evaluation in test method of copper to superconductor volume ratio of Cu/Nb-Ti composite superconductors' (Annex F).

Supraleitfähigkeit - Teil 5: Messung des Verhältnisses von Matrixvolumen zu Supraleitervolumen - Verhältnis von Kupfervolumen zu Supraleitervolumen von Cu/Nb-Ti Verbundsupraleiterdrähten

Supraconductivité - Partie 5 : Mesure du rapport volumique matrice/supraconducteur - Rapport volumique cuivre/supraconducteur des fils en composite supraconducteur Cu/Nb-Ti

La IEC 61788-5:2013 spécifie une méthode d'essai pour déterminer le rapport volumique cuivre/supraconducteur de fils en composite supraconducteur Cu/Nb-Ti. Cette méthode d'essai et l'autre méthode de l'Annexe A sont destinées à être utilisées avec des fils en composite supraconducteur Cu/Nb-Ti ayant une section de 0,1 mm2 à 3 mm2, un diamètre du ou des filaments de Nb-Ti de 2 micromètres à 200 micromètres et un rapport volumique cuivre/supraconducteur supérieur ou égal à 0,5. Le conducteur d'essai composite Cu/Nb-Ti présenté dans cette méthode possède une structure monolithique avec une section ronde ou rectangulaire. Cette méthode d'essai est réalisée en dissolvant le cuivre dans de l'acide nitrique. Les écarts par rapport à cette méthode d'essai qui sont admis pour les essais périodiques et les autres restrictions spécifiques sont mentionnés dans la présente norme. Les fils en composite supraconducteur Cu/Nb-Ti dépassant les limites de la section, du diamètre de filament et du rapport volumique cuivre/supraconducteur peuvent être mesurés avec la présente méthode au moyen d'une réduction d'incertitude anticipée. D'autres géométries d'éprouvettes plus spécialisées peuvent être plus appropriées à des conducteurs dépassant les limites et ont été omises de la présente norme pour la simplifier et pour conserver une faible incertitude. On s'attend à appliquer la méthode d'essai donnée dans cette norme à d'autres fils en composite supraconducteur après y avoir apporté certaines modifications appropriées. Le rapport volumique cuivre/supraconducteur des composites supraconducteurs est utilisé principalement pour calculer la densité de courant critique des fils supraconducteurs. L'essai effectué avec la méthode donnée dans la présente Norme internationale peut être utilisé pour fournir une partie des informations nécessaires pour déterminer la pertinence d'un supraconducteur spécifique. De plus, cette méthode est utile pour le contrôle qualité, l'essai d'acceptation ou de recherche si les précautions données dans cette norme sont observées. Cette deuxième édition annule et remplace la première édition parue en 2000, dont elle constitue une révision technique. Les principales révisions sont l'ajout de deux nouvelles annexes, 'Considérations relatives à l'incertitude' (Annexe E) et 'Évaluation de l'incertitude de la méthode d'essai du rapport volumique cuivre/supraconducteur des composites supraconducteurs Cu/Nb-Ti' (Annexe F).

Superprevodnost - 5. del: Matrika za merjenje superprevodniškega volumenskega razmerja - Razmerje med bakrom in superprevodniškim volumenskim razmerjem superprevodnih žic iz kompozita Cu/Nb-Ti (IEC 61788-5:2013)

Ta del standarda IEC 61788 opisuje preskusno metodo za merjenje razmerja med bakrom in superprevodniškim volumenskim razmerjem superprevodnih žic iz kompozita Cu/Nb-Ti. Ta testna metoda in alternativna metoda v dodatku A sta namenjeni za uporabo pri superprevodnih žicah iz kompozita Cu/Nb-Ti s prerezom od 0,1 do 3 mm2, premerom filamentov Nb-Ti od 2 do 200 μm ter razmerjem med bakrom in superprevodniškim volumenskim razmerjem 0,5 ali več. Preskušani prevodnik iz kompozita Cu/Nb-Ti iz te metode ima monolitno strukturo z okroglim ali pravokotnim prerezom. Ta preskusna metoda se izvede z raztapljanjem bakra z dušikovo kislino. Odstopanja od te testne metode, ki so dovoljena za rutinske preskuse in druge specifične omejitve, so navedena v tem standardu. Superprevodne žice iz kompozita Cu/Nb-Ti, ki presegajo mejne vrednosti prereza, premera filamenta in razmerja med bakrom in superprevodniškim volumenskim razmerjem, se lahko izmerijo s to metodo s pričakovanim zmanjšanjem negotovosti. Druge, bolj specializirane, preskusne geometrije preskusnih vzorcev so morda bolj primerne za prevodnike, ki presegajo mejne vrednosti, ter zaradi poenostavitve in za zagotovitev nizke negotovosti niso vključene v tem standardu. Preskusna metoda, navedena v tem standardu, se predvidoma lahko uporablja za druge superprevodne kompozitne žice po nekaterih ustreznih prilagoditvah.

General Information

Status
Published
Publication Date
05-Sep-2013
Technical Committee
Drafting Committee
Current Stage
6060 - Document made available
Due Date
02-Oct-2013
Completion Date
06-Sep-2013

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SLOVENSKI STANDARD
SIST EN 61788-5:2014
01-maj-2014
1DGRPHãþD
SIST EN 61788-5:2002
Superprevodnost - 5. del: Matrika za merjenje superprevodniškega volumenskega
razmerja - Razmerje med bakrom in superprevodniškim volumenskim razmerjem
superprevodnih žic iz kompozita Cu/Nb-Ti (IEC 61788-5:2013)

Superconductivity - Part 5: Matrix to superconductor volume ratio measurement - Copper

to superconductor volume ratio of Cu/Nb-Ti composite superconducting wires
Supraleitfähigkeit - Teil 5: Messung des Verhältnisses von Matrixvolumen zu

Supraleitervolumen - Verhältnis von Kupfervolumen zu Supraleitervolumen von Cu/NbTi-

Verbundsupraleitern

Supraconductivté - Partie 5 : Mesure du rapport volumique matrice/supraconducteur -

Rapport volumique cuivre/supraconducteur des fils en composite supraconducteur
Cu/Nb-Ti
Ta slovenski standard je istoveten z: EN 61788-5:2013
ICS:
17.220.20 0HUMHQMHHOHNWULþQLKLQ Measurement of electrical
PDJQHWQLKYHOLþLQ and magnetic quantities
29.050 Superprevodnost in prevodni Superconductivity and
materiali conducting materials
SIST EN 61788-5:2014 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN 61788-5:2014
---------------------- Page: 2 ----------------------
SIST EN 61788-5:2014
EUROPEAN STANDARD
EN 61788-5
NORME EUROPÉENNE
September 2013
EUROPÄISCHE NORM
ICS 17.220.20; 29.050 Supersedes EN 61788-5:2001
English version
Superconductivity -
Part 5: Matrix to superconductor volume ratio measurement -
Copper to superconductor volume ratio of Cu/Nb-Ti composite
superconducting wires
(IEC 61788-5:2013)
Supraconductivité - Supraleitfähigkeit -
Partie 5 : Mesure du rapport volumique Teil 5: Messung des Verhältnisses von
matrice/supraconducteur - Matrixvolumen zu Supraleitervolumen -
Rapport volumique Verhältnis von Kupfervolumen zu
cuivre/supraconducteur des fils en Supraleitervolumen von Cu/Nb-Ti
composite supraconducteur Cu/Nb-Ti Verbundsupraleiterdrähten
(CEI 61788-5:2013) (IEC 61788-5:2013)

This European Standard was approved by CENELEC on 2013-07-02. CENELEC members are bound to comply

with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard

the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on

application to the CEN-CENELEC Management Centre or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other

language made by translation under the responsibility of a CENELEC member into its own language and notified

to the CEN-CENELEC Management Centre has the same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus,

the Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany,

Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland,

Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B - 1000 Brussels

© 2013 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.

Ref. No. EN 61788-5:2013 E
---------------------- Page: 3 ----------------------
SIST EN 61788-5:2014
EN 61788-5:2013 - 2 -
Foreword

The text of document 90/321/FDIS, future edition 2 of IEC 61788-5, prepared by IEC/TC 90

"Superconductivity" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as

EN 61788-5:2013.
The following dates are fixed:
(dop) 2014-04-02
• latest date by which the document has to be
implemented at national level by
publication of an identical national
standard or by endorsement
• latest date by which the national (dow) 2016-07-02
standards conflicting with the
document have to be withdrawn
This document supersedes EN 61788-5:2001.

EN 61788-5:2013 includes the following significant technical changes with respect to

EN 61788-5:2001:

The main revisions are the addition of two new annexes, "Uncertainty considerations" (Annex E) and

"Uncertainty evaluation in test method of copper to superconductor volume ratio of Cu/Nb-Ti

composite superconductors" (Annex F).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CENELEC [and/or CEN] shall not be held responsible for identifying any or all such

patent rights.
Endorsement notice

The text of the International Standard IEC 61788-5:2013 was approved by CENELEC as a European

Standard without any modification.
---------------------- Page: 4 ----------------------
SIST EN 61788-5:2014
- 3 - EN 61788-5:2013
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following documents, in whole or in part, are normatively referenced in this document and are

indispensable for its application. For dated references, only the edition cited applies. For undated

references, the latest edition of the referenced document (including any amendments) applies.

NOTE When an international publication has been modified by common modifications, indicated by (mod), the relevant EN/HD

applies.
Publication Year Title EN/HD Year
IEC 60050-815 Series International Electrotechnical Vocabulary - -
(IEV)
---------------------- Page: 5 ----------------------
SIST EN 61788-5:2014
---------------------- Page: 6 ----------------------
SIST EN 61788-5:2014
IEC 61788-5
Edition 2.0 2013-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Superconductivity –
Part 5: Matrix to superconductor volume ratio measurement – Copper to
superconductor volume ratio of Cu/Nb-Ti composite superconducting wires
Supraconductivité –
Partie 5: Mesure du rapport volumique matrice/supraconducteur – Rapport
volumique cuivre/supraconducteur des fils en composite supraconducteur
Cu/Nb-Ti
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX T
ICS 17.220.20; 29.050 ISBN 978-2-83220-831-1

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
---------------------- Page: 7 ----------------------
SIST EN 61788-5:2014
– 2 – 61788-5 © IEC:2013
CONTENTS

FOREWORD ........................................................................................................................... 3

INTRODUCTION ..................................................................................................................... 5

1 Scope ............................................................................................................................... 6

2 Normative references ....................................................................................................... 6

3 Terms and definitions ....................................................................................................... 6

4 Principle ........................................................................................................................... 7

5 Chemicals ........................................................................................................................ 7

6 Apparatus ......................................................................................................................... 7

7 Measurement procedure ................................................................................................... 8

7.1 Quantity of specimen ............................................................................................... 8

7.2 Removal of insulating cover material ....................................................................... 8

7.3 Cleaning .................................................................................................................. 8

7.4 Drying ..................................................................................................................... 8

7.5 Measurement of specimen mass and its repetition ................................................... 8

7.6 Dissolving copper .................................................................................................... 8

7.7 Cleaning and drying the Nb-Ti filaments .................................................................. 9

7.8 Measurement of dissolved specimen mass and its repetition ................................... 9

7.9 Procedural repetition for second specimen ............................................................ 10

8 Calculation of results ...................................................................................................... 10

9 Uncertainty of the test method ........................................................................................ 10

10 Test report ...................................................................................................................... 11

10.1 Identification of test specimen ............................................................................... 11

10.2 Report of copper to superconductor volume ratio ................................................... 11

10.3 Report of test conditions ........................................................................................ 11

Annex A (normative) Copper to superconductor volume ratio – copper mass method .......... 12

Annex B (informative) Specific mass depending on Nb-Ti fraction ....................................... 14

Annex C (information) Mechanical removal of insulating cover materials ............................ 15

Annex D (informative) Second etch of specimen ................................................................. 16

Annex E (informative) Uncertainty considerations ............................................................... 17

Annex F (informative) Uncertainty evaluation in the test method of copper to

superconductor volume ratio of Cu/Nb-Ti composite superconductors ................................... 22

Table B.1 – Specific mass of Nb-Ti ....................................................................................... 14

Table E.1 – Output signals from two nominally identical extensometers ................................ 18

Table E.2 – Mean values of two output signals ..................................................................... 18

Table E.3 – Experimental standard deviations of two output signals ...................................... 18

Table E.4 – Standard uncertainties of two output signals ...................................................... 19

Table E.5 – Coefficient of variations of two output signals ..................................................... 19

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SIST EN 61788-5:2014
61788-5 © IEC:2013 – 3 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
SUPERCONDUCTIVITY –
Part 5: Matrix to superconductor volume ratio measurement –
Copper to superconductor volume ratio of Cu/Nb-Ti composite
superconducting wires
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international

co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and in

addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,

Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC Publication(s)”). 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. 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 IEC on technical matters express, as nearly as possible, an international

consensus of opinion on the relevant subjects since each technical committee has representation from all

interested IEC National Committees.

3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC

Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

misinterpretation by any end user.

4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

transparently to the maximum extent possible in their national and regional publications. Any divergence between

any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.

5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity

assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any

services carried out by independent certification bodies.

6) All users should ensure that they have the latest edition of this publication.

7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and

members of its technical committees and IEC National Committees for any personal injury, property damage or

other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and expenses

arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC Publications.

8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

indispensable for the correct application of this publication.

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent

rights. 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.

This second edition cancels and replaces the first edition published in 2000. It constitutes a

technical revision. The main revisions are the addition of two new annexes, "Uncertainty

considerations" (Annex E) and "Uncertainty evaluation in test method of copper to

superconductor volume ratio of Cu/Nb-Ti composite superconductors" (Annex F).
The text of this standard is based on the following documents:
FDIS Report on voting
90/321/FDIS 90/324/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.
---------------------- Page: 9 ----------------------
SIST EN 61788-5:2014
– 4 – 61788-5 © IEC:2013

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

A list of all parts of the IEC 61788 series, published under the general title Superconductivity,

can be found on the IEC website.

The committee has decided that the contents of this publication will remain unchanged until the

stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data related to

the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
---------------------- Page: 10 ----------------------
SIST EN 61788-5:2014
61788-5 © IEC:2013 – 5 –
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 or the Nb-Ti alloy fraction is known and Annex B can be used to estimate

the specific mass. If the specific mass of Nb-Ti is unknown and the Nb-Ti alloy fraction is

unknown and/or the fraction of Nb barrier is unknown, another method to determine the copper

to superconductor volume ratio of composite superconductors is described in Annex A.

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SIST EN 61788-5:2014
– 6 – 61788-5 © IEC:2013
SUPERCONDUCTIVITY –
Part 5: Matrix to superconductor volume ratio measurement –
Copper to superconductor volume ratio of Cu/Nb-Ti composite
superconducting wires
1 Scope

This part of IEC 61788 covers a test method for the determination of copper to superconductor

volume ratio of Cu/Nb-Ti composite superconducting wires.

This test method and the alternate method in Annex A are intended for use with Cu/Nb-Ti

2 2

composite superconducting wires with a 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 composite superconducting wires 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 of uncertainty. 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 low uncertainty.

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 documents, in whole or in part, are normatively referenced in this document and

are indispensable for its application. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments)

applies.

IEC 60050-815 (all parts), International Electrotechnical Vocabulary (available at

)
3 Terms and definitions

For the purposes of this document, the definitions given in IEC 60050-815 as well as the

following definition apply.
3.1
copper to superconductor volume ratio

ratio of the volume of the copper stabilizing material to the volume without copper consisting of

Nb-Ti filaments and their Nb barriers
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SIST EN 61788-5:2014
61788-5 © IEC:2013 – 7 –
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 into the nitric acid solution to dissolve only the

copper.
Then measure the mass of the remaining Nb-Ti filaments and their Nb barriers.

The volume and mass of the starting wire and the mass of the filaments are used to determine

the copper to superconductor volume ratio.
5 Chemicals
The following chemicals shall be prepared for sample preparation:

a) nitric acid solution consisting of nitric acid (a volume fraction of 50 % to 65 % recommended)

and distilled water;
b) organic solvent;
c) degreasing solvent;
d) ethyl alcohol;
e) distilled (pure) water.

NOTE When nitric acid of more than a mass fraction of 65 % is used, the acid is diluted with distilled water within

the range of the above content.
6 Apparatus
The following apparatus shall be prepared.
• Draft chamber
• Balance

A balance shall have a manufacturer’s specified uncertainty of ±0,1 mg or better.

• Dryer or drying oven

A dryer or a drying oven shall be used for evaporating moisture after washing the specimen.

• Beaker
• Watch-glass
• Plastic tweezers
• Filter papers
• Thermometer
• Rubber gloves and protection spectacles

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.
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SIST EN 61788-5:2014
– 8 – 61788-5 © IEC:2013
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 remains.

If no organic solvents can remove the insulating cover material, the mechanical removal in

Annex C is an alternative.
7.3 Cleaning

A degreaser shall be used to remove oil and/or grease traces from the specimen, whose cover

material has been removed. It shall then be cleaned with pure water. Finally, the degreased

specimen shall be dipped into ethyl alcohol to replace the water. Cleaning without using ethyl

alcohol is an alternative, by using the drying process described in 7.4.
7.4 Drying

The clean specimen shall be placed on a watch-glass and dried fully in a dryer or a drying oven

at a temperature of 60 °C or lower with the holding time more than 0,5 hours. When cleaning

the specimen is carried out without ethyl alcohol, the specimen shall be dried fully in a dryer or

a drying oven at a temperature of 100 °C with the holding time more than 0,5 hours.

7.5 Measurement of specimen mass and its repetition

When the specimen is cooled down to 35 °C or lower, its mass shall be measured on a sheet of

weighing paper, using a balance with a manufacturer’s specified uncertainty of ±0,1 mg or

better.

After completion of this mass measurement (the first measurement), remove the specimen from

the balance.

To assure that the specimen has been fully dried, the mass of the specimen shall be measured

again about 10 min after the first measurement (the second measurement).

The difference in mass between the first and second measurements shall be within ±0,5 %. If

this difference is within ±0,5 %, the average of the two measurements shall be regarded as the

mass of the specimen.

If the difference in mass is more than ±0,5 %, cleaning of the specimen with ethyl alcohol and

drying of the specimen shall be repeated as described in 7.3, 7.4 and 7.5 until the difference in

mass of the two measurements is within ±0,5 %.

As soon as this part of the method is qualified by a successful repetition, the second mass

measurement can be omitted in subsequent measurements. However, periodic re-qualification

shall be performed every six months or after changes of equipment or personnel.
7.6 Dissolving copper
The copper shall be dissolved from the specimen in the following manner.
---------------------- Page: 14 ----------------------
SIST EN 61788-5:2014
61788-5 © IEC:2013 – 9 –

Put approximately 150 ml of the nitric acid solution in a 300 ml beaker. Tie a knot in the

specimen to help retain all of the filaments upon completion of the etch. In the draft chamber,

while maintaining the temperature of the nitric acid solution between 20 °C and 50 °C, the

whole specimen shall be dipped into the nitric acid solution for 30 min to 1 h to completely

dissolve the copper of the specimen. It shall be checked visually that the copper has been

completely dissolved. For wires with filaments less than 10 µm, the second etch according to

Annex D is recommended to assure a complete copper dissolution.

Note that a fresh nitric acid solution shall be used for each specimen that is etched.

When copper is dissolved in the nitric acid solution, nitrite gas is generated. Because the nitric

acid and the nitrite gas are harmful to the human body, use all safety precautions in handling

acids such as wearing protective clothing and carrying out work to dissolve the copper in the

draft chamber. In addition, the fumes generated during storage and use are harmful. Normal

safety precautions for acid storage, use and disposal shall be followed.

Use rubber gloves, protection spectacles and a pair of plastic tweezers during the treatment of

the nitric acid solution.

NOTE The temperature of the nitric acid solution specified here is that before dipping the specimen in it. The

temperature can rise to more than 50 °C when dissolution of the copper is in progress.

When mixing the solution, always add the nitric acid to the water.
7.7 Cleaning and drying the Nb-Ti filaments

Cleaning and drying the Nb-Ti filaments shall be performed in the following manner.

Acid shall be carefully poured out of the beaker into a plastic sewage reservoir, keeping the

specimen in the beaker so as not to lose any broken filaments. The beaker shall be refilled with

distilled water to rinse. The water shall be carefully poured out of the beaker. The beaker shall

now be refilled, with ethyl alcohol this time to replace any remaining water. Now to dry all of the

filaments fully, the specimen shall be placed, using plastic tweezers, on a sheet of filter paper

with any broken or loose filaments. They shall then be placed in a dryer or a drying oven

(see 7.4).

If a green stain is noticed on the filter paper, then there is acid remaining on the filaments. This

acid shall be removed by rinsing again in alcohol.

Cleaning without using ethyl alcohol is an alternative, by using the drying process described

in 7.4.

If there are too many broken filaments, the procedures shall be repeated from the beginning on

a new specimen.

Nb-Ti filaments with a diameter of about 10 µm or less can be combustible when they are

removed from the acid and exposed to air after the matrix has been removed. Ignition sources

(including flame, heat, spark and electrostatic discharge) are avoided. In addition, tweezers

shall be used to handle the etched filaments and they shall not be put in contact with any part of

the body. Normal safety precautions for metal combustion hazards shall be followed.

7.8 Measurement of dissolved specimen mass and its repetition

When the specimen is cooled down to 35 °C or lower, using a balance with a manufacturer’s

specified uncertainty of ±0,1 mg or better, the specimen shall be weighed as in 7.5. A sheet of

weighing paper shall be used for the measurement to avoid losing broken filaments (the first

measurement).
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SIST EN 61788-5:2014
– 10 – 61788-5 © IEC:2013

After completion of the mass measurement described in 7.5, the Nb-Ti filaments shall be

removed from the balance. To know whether the Nb-Ti filaments have been fully dried, the

mass of the Nb-Ti filaments shall be weighed again about 10 min after the first measurement

(the second measurement).

The difference in mass shall be within ±0,5 % between the second measurement and the first

measurement. If the difference in mass is within ±0,5 % between the two measurements, the

average of the masses of the two measurements shall be regarded as the mass of the

filaments.

If the difference in mass of the two measurements is more than ±0,5 %, only cleaning with ethyl

alcohol and drying shall be repeated as described in the procedural step of 7.7, and then

procedural steps shall be repeated again in the procedural step of 7.5. Then, check again to

make sure that the difference in mass of the two measurements is within ±0,5 %.

As soon as this part of the method is qualified by a successful repetition, the second mass

measurement can be omitted in subsequent measurements. However, periodic re-qualification

shall be performed every six months or after changes in equipment or personnel.
7.9 Procedural repetition for second specimen

The procedural steps in 7.1 through 7.8 shall be repeated on the second specimen.

As soon as the method is qualified by a successful repetition, the repeated measurements on

the second specimen can be omitted in subsequent measurements. However, periodic

re-qualification shall be performed every six months or after changes in equipment or

personnel.
8 Calculation of results

For each measurement, the copper to superconductor volume ratio shall be obtained down to

two decimal places in the following equation, by rounding
...

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