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1、DRAFT FOR DEVELOPMENT DD ISO/TS 17576:2004 Dentistry Corrosion tests for amalgam ICS 11.060.10 ? Licensed Copy: London South Bank University, London South Bank University, Sat Aug 18 09:36:45 GMT+00:00 2007, Uncontrolled Copy, (c) BSI DD ISO/TS 17576:2004 This Draft for Development was published und
2、er the authority of the Standards Policy and Strategy Committee on 31 August 2007 BSI 2007 ISBN 978 0 580 59698 8 National foreword This Draft for Development is the UK implementation of ISO/TS 17576:2004. This publication is not to be regarded as a British Standard. It is being issued in the Draft
3、for Development series of publications and is of a provisional nature. It should be applied on this provisional basis, so that information and experience of its practical application can be obtained. Comments arising from the use of this Draft for Development are requested so that UK experience can
4、be reported to the international organization responsible for its conversion to an international standard. A review of this publication will be initiated not later than 3 years after its publication by the international organization so that a decision can be taken on its status. Notification of the
5、start of the review period will be made in an announcement in the appropriate issue of Update Standards. According to the replies received by the end of the review period, the responsible BSI Committee will decide whether to support the conversion into an international Standard, to extend the life o
6、f the Technical Specification or to withdraw it. Comments should be sent to the Secretary of the responsible BSI Technical Committee at British Standards House, 389 Chiswick High Road, London W4 4AL. The UK participation in its preparation was entrusted by Technical Committee CH/106, Dentistry, to S
7、ubcommittee CH/106/1, Dental restorative and orthodontic materials. A list of organizations represented on this committee can be obtained on request to its secretary. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct applic
8、ation. Amendments issued since publication Amd. No. DateComments Licensed Copy: London South Bank University, London South Bank University, Sat Aug 18 09:36:45 GMT+00:00 2007, Uncontrolled Copy, (c) BSI Reference number ISO/TS 17576:2004(E) TECHNICAL SPECIFICATION ISO/TS 17576 First edition 2004-01-
9、15 Dentistry Corrosion tests for amalgam Art dentaire Essais de corrosion des amalgames DD ISO/TS 17576:2004 Licensed Copy: London South Bank University, London South Bank University, Sat Aug 18 09:36:45 GMT+00:00 2007, Uncontrolled Copy, (c) BSI ii Licensed Copy: London South Bank University, Londo
10、n South Bank University, Sat Aug 18 09:36:45 GMT+00:00 2007, Uncontrolled Copy, (c) BSI iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried
11、out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO
12、collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare Internationa
13、l Standards. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. In other circumstances, particularly when there is an urgent
14、 market requirement for such documents, a technical committee may decide to publish other types of normative document: an ISO Publicly Available Specification (ISO/PAS) represents an agreement between technical experts in an ISO working group and is accepted for publication if it is approved by more
15、 than 50 % of the members of the parent committee casting a vote; an ISO Technical Specification (ISO/TS) represents an agreement between the members of a technical committee and is accepted for publication if it is approved by 2/3 of the members of the committee casting a vote. An ISO/PAS or ISO/TS
16、 is reviewed after three years in order to decide whether it will be confirmed for a further three years, revised to become an International Standard, or withdrawn. If the ISO/PAS or ISO/TS is confirmed, it is reviewed again after a further three years, at which time it must either be transformed in
17、to an International Standard or be withdrawn. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO/TS 17576 was prepared by Technical Committee ISO/TC
18、 106, Dentistry, Subcommittee SC 1, Filling and restorative materials. DD ISO/TS 17576:2004 Licensed Copy: London South Bank University, London South Bank University, Sat Aug 18 09:36:45 GMT+00:00 2007, Uncontrolled Copy, (c) BSI iv Introduction The development of this Technical Specification is the
19、 result of worldwide demand for test methods to determine acceptability of dental amalgams for oral restorations in relation to corrosion and mercury vapour. The test methods described in ISO 10271 are intended for dental metallic materials and are not suitable for amalgams, due to the risk of forma
20、tion of precipitates during the test. Furthermore, ISO 10271 does not cover measurement of mercury vapour liberated during corrosion of amalgam. DD ISO/TS 17576:2004 Licensed Copy: London South Bank University, London South Bank University, Sat Aug 18 09:36:45 GMT+00:00 2007, Uncontrolled Copy, (c)
21、BSI 1 Dentistry Corrosion tests for amalgam 1 Scope This Technical Specification provides two test methods and concomitant protocols to determine the corrosive behaviour of dental amalgams and their tendency to release mercury vapour during corrosion. The methods measure 1) the integrated current in
22、 a potentiostatic corrosion test and 2) the amount of released ions and mercury vapour in a static immersion test. This Technical Specification is not intended to set limits for the relevant parameters in the two tests described. 2 Normative references The following referenced documents are indispen
23、sable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 1559:1995, Dental materials Alloys for dental amalgam ISO 3585:1998, Borosilicate glass 3.3
24、Properties ISO 3696:1987, Water for analytical laboratory use Specification and test methods ISO 10271:2001, Dental metallic materials Corrosion test methods 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 amalgam alloy of mercury with one or
25、 more other metals 3.2 corrosion deterioration of an amalgam by chemical or electrochemical reaction with its environment NOTE This deterioration is manifest in the loss in mass of the amalgam, with a release of constituent elements or the formation of an adherent film of reaction products. 3.3 elec
26、trolyte liquid that contains ions whose combination allows the conduction of electricity 3.4 immersion test test in which the sample is exposed to a corrosive solution without application of variable mechanical stresses to the sample 3.5 potentiostatic test test in which the electrode potential is k
27、ept constant DD ISO/TS 17576:2004 Licensed Copy: London South Bank University, London South Bank University, Sat Aug 18 09:36:45 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 2 4 Test methods 4.1 Potentiostatic corrosion test for dental amalgam 4.1.1 Specimen preparation Prepare an amalgam specimen of
28、the type for the measurement of compression strength, in accordance with ISO 1559. Condition in air at (37 2) C for (7,0 0,1) days. Attach an insulated lead to the specimen for connection to the potentiostat. Cover the connecting lead junction and all surfaces except one end of the specimen with an
29、insulating material, preferably by casting in epoxy resin. The temperature rise during setting of the resin shall not exceed 15 C. This material shall not dissolve in or react with the electrolyte. Wet-grind the exposed end of the specimen uniformly to ASTM 600 or FEPA 1200 using silicon carbide sur
30、face abrasive paper. Wash with distilled water. Eliminate the crevice between the amalgam and the embedding materials by casting or masking. The testing laboratory may develop its own method of specimen preparation, provided the above procedures are included and the conditions are met. 4.1.2 Reagent
31、s 4.1.2.1 Electrolyte, of volume W 300 ml. Make up a fresh solution of NaCl c(NaCl = 0,154 mol/l) by adding (9,0 0,1) g analytical grade NaCl to 600 ml water (ISO 3696, Grade 2), then make up this solution to (1000,0 0,5) ml. 4.1.3 Apparatus 4.1.3.1 Corrosion cell. Use a three-electrode corrosion ce
32、ll holding the specimen (working electrode), a reference electrode probe, and an inert counter-electrode (platinum or carbon is recommended). 4.1.3.2 Temperature control, consisting of a jacket and temperature control/circulator, or a temperature- controlled bath, capable of maintaining (37,0 0,5) C
33、 in the cell. 4.1.3.3 Reference electrode and its control. Use any standard reference electrode with a stable potential of known potential difference from a standard hydrogen electrode (SHE). Control the potential at (0,000 0,002) V vs. a saturated calomel electrode (SCE) at 25 C, equivalent to (0,2
34、415 0,002) V (SHE). The reference potential values for some other common reference electrodes and corresponding values for the control potential settings are shown in Table 1. Other electrodes can be used based on their known potential difference from SHE. 4.1.3.4 Electronic potentiostat, capable of
35、 a current output W 100 mA, a voltage output W 10 V, and a potential control accurate and stable to 1 mV. The hardware/software used shall allow either recording the current for 24 h or integrating the current for 24 h. DD ISO/TS 17576:2004 Licensed Copy: London South Bank University, London South B
36、ank University, Sat Aug 18 09:36:45 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 3 4.1.4 Test set-up 4.1.4.1 Temperature of the reference electrode Measure the temperature of the reference electrode (4.1.3.3). If necessary, adjust the temperature to (25 1) C by the control potential using the temperat
37、ure coefficient for the given electrode type. Temperature coefficients and examples of potential correction are shown in Table 1. Table 1 Potential settings for different reference electrodes and temperatures of the reference electrodes Reference potential Control potential setting /V (SHE) /V when
38、the temperature of the reference electrode is when the temperature of the reference electrode is Reference electrode type Reference electrolyte Temperature coefficient1 V/K 18 C 25 C 37 C 18 C 25 C 37 C Saturated calomel (SCE) Saturated KCl 7,50 104 0,2468 0,2415 0,2325 0,005 0,000 0,009 1,0 M calom
39、el 1 mol/l KCl 2,40 104 0,2817 0,2800 0,2771 0,040 0,039 0,036 0,1 calomel 0,1 mol/l KCl 7,00 105 0,3342 0,3337 0,3329 0,093 0,092 0,091 0,1 silver chloride 0,1 mol/l KCl 6,50 104 0.2927 0,2881 0,2803 0,051 0,047 0,039 4.1.4.2 Positioning of the reference electrode During the polarization part of th
40、e procedure, place the reference electrode probe close to the working electrode (amalgam) surface without touching the surface or shielding substantially the specimen surface. Also, the electrolyte of the reference electrode shall not contaminate the electrolyte in the vicinity of the amalgam. This
41、is commonly achieved by placing the reference electrode in a separate compartment and using a “salt-bridge” between the reference electrode compartment and the main cell. The salt-bridge is a tube filled with the electrolyte and ending in a capillary (“Luggin capillary”), the end of which is placed
42、close to the tested surface. The tip of the capillary should be at a distance from the amalgam surface equal to about two outer diameters of the tip. 4.1.5 Test procedure Fill the corrosion cell (4.1.3.1) with electrolyte (4.1.2.1). Leave the cell open to the atmosphere. However, the cell should be
43、covered with a lid to prevent excessive evaporation of the electrolyte. Using the temperature control (4.1.3.2), heat the cell and maintain at a temperature of (37,0 0,5) C. Insert the specimen, connect the specimen and electrodes to the potentiostat (4.1.3.4) (no potential control) and wait (10,0 0
44、,1) min. During this potential stabilization it is advisable to stir the solution, e.g. using a magnetic stirrer and a stirring bar in the cell. Record the potential at the end of the (10,0 0,1) min exposure period. Stirring also may be used during this open-circuit potential measurement. Set the po
45、tentiostat to the appropriate control potential (see Table 1) and time (24 h). Apply the potential and record or integrate current for (24,0 0,2) h. During this polarization part of the test, the solution should remain stagnant (no stirring). DD ISO/TS 17576:2004 Licensed Copy: London South Bank Uni
46、versity, London South Bank University, Sat Aug 18 09:36:45 GMT+00:00 2007, Uncontrolled Copy, (c) BSI 4 4.1.6 Data acquisition and processing a) Coulometer method A convenient method of data acquisition is to use an electronic current integrator (coulometer) in the circuit between the potentiostat a
47、nd the cell. The reading of the coulometer after 24 h of polarization is the anodic charge. b) Computer-controlled potentiostat method An equally convenient procedure is to use a computer-controlled potentiostat with a program for potentiostatic control and software which allows post-test integratio
48、n of the recorded current as displayed on the screen1). c) Data-logging and integration method If neither a) nor b) is available, record the polarization current using any available data acquisition system. The integration then can be performed by averaging all the current data and multiplying the a
49、verage current, in amperes, by the total exposure time, in seconds (assuming that the time between current measurements was constant), or using any other suitable and accurate integration method. In a) and b) make sure that the integration procedure uses the true values of current rather than the log of current. For instance, if the current is strip-chart-recorded on a logarithmic scale, or the results have been exported as a te