1、BRITISH STANDARD BS EN 821-3:2005 Advanced technical ceramics Monolithic ceramics. Thermophysical properties Part 3: Determination of specific heat capacity The European Standard EN 821-3:2005 has the status of a British Standard ICS 81.060.99 BS EN 821-3:2005 This British Standard was published und
2、er the authority of the Standards Policy and Strategy Committee on 20 April 2005 BSI 20 April 2005 ISBN 0 580 45855 5 National foreword This British Standard is the official English language version of EN 821-3:2005. It supersedes DD ENV 821-3:1994 which is withdrawn. The UK participation in its pre
3、paration was entrusted to Technical Committee RPI/13, Advanced technical ceramics, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publ
4、ications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the ne
5、cessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the in
6、terpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 18, an inside back cover and
7、a back cover. The BSI copyright notice displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date Comments EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 821-3 January 2005 ICS 81.060.99 Supersedes ENV 821-3:1993 English version Ad
8、vanced technical ceramics - Monolithic ceramics. Thermo- physical properties - Part 3: Determination of specific heat capacity Cramiques techniques avances - Cramiques monolithiques. Proprits thermophysiques - Partie 3 : Dtermination de la chaleur spcifique Hochleistungskeramik - Monolithische Keram
9、ik - Thermophysikalische Eigenschaften - Teil 3: Bestimmung der spezifischen Wrmekapazitt This European Standard was approved by CEN on 9 December 2004. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the stat
10、us 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 Central Secretariat or to any CEN member. This European Standard exists in three official versions (English, French, German). A v
11、ersion in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Es
12、tonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES
13、 KOMITEE FR NORMUNG Management Centre: rue de Stassart, 36 B-1050 Brussels 2005 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 821-3:2005: EEN 821-3:2005 (E) 2 Contents Page Foreword3 1 Scope 4 2 Normative references 4 3 Terms and
14、 definitions .4 4 Method A Drop calorimetry5 5 Method B Differential scanning calorimetry (DSC) .8 6 Report .10 Bibliography 18 EN 821-3:2005 (E) 3 Foreword This document (EN 821-3:2005) has been prepared by Technical Committee CEN/TC 184 “Advanced technical ceramics”, the secretariat of which is he
15、ld by BSI. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by August 2005, and conflicting national standards shall be withdrawn at the latest by August 2005. EN 821 Advanced technical ceramics Monol
16、ithic ceramics - Thermo-physical properties consists of the following parts: Part 1: Determination of thermal expansion Part 2: Determination of thermal diffusivity by the laser flash (or heat pulse) method Part 3: Determination of specific heat capacity This document supersedes ENV 821-3:1993 Accor
17、ding to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuan
18、ia, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EN 821-3:2005 (E) 4 1 Scope This document specifies two methods for the determination of specific heat capacity of advanced monolithic technical ceramic materials based on
19、 drop calorimetry (Method A) and differential scanning calorimetry (DSC, Method B) over a temperature range from room temperature upwards, depending on the design of the equipment. NOTE 1 The methods described apply in the case of test materials free from phase transformations, annealing effects or
20、partial melting. If any such effect occurs in a material over the temperature range of the test, spurious results will be obtained unless the data are carefully analysed. In such cases it is usually necessary to conduct repeat tests at a number of temperatures close to the discontinuity, in order to
21、 estimate correctly its contribution to the apparent heat capacity. NOTE 2 Care should be exercised in both methods over the selection of the cell or crucible material and in the selection of the test atmosphere, especially at high temperatures. Test pieces can react with the crucible or the atmosph
22、ere, leading to spurious results. In general, an awareness of such problems should be maintained at all times. Especially with regard to Method B, awareness should also be maintained of radiation effects at temperatures above 1000 C, and of the reproducibility of the output signal. 2 Normative refer
23、ences The following referenced documents are indispensable 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. EN 60584-1, Thermocouples Part 1: Reference
24、 tables EN 60584-2, Thermocouples Part 2: Tolerances EN ISO/IEC 17025: 2000, General requirements for the competence of testing and calibration laboratories (ISO/IEC 17025:1999) 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 enthalpy, H heat
25、 content of an object in joules released or absorbed as a result of a temperature change. 3.2 specific heat capacity, c pamount of heat (q) in joules required to raise the temperature of a 1 g mass by 1 C at temperature T at constant pressure, in accordance with the equation dT dQm 1= dT dq= c p( 1
26、) where Q is the total heat required for a test piece of mass m. EN 821-3:2005 (E) 5 3.3 mean specific heat capacity, c pamount of heat (q) required to raise the temperature of a 1 g mass from temperature T 1to temperature T 2 , divided by the temperature interval in degrees Celsius at constant pres
27、sure, i.e: ) T- T m( H= ) T- T m( ) TT Q(= T- T ) TT q(= c 1 2 1 2 2 1 1 2 2 1 p (2) 3.4 calorimeter device for measuring the amount of heat input to or output from a test piece. 3.5 drop calorimeter calorimeter into which a test piece at initially high temperature is dropped and allowed to cool, an
28、d the total heat content (enthalpy) of the test piece is measured as a temperature rise or other parameter in the calorimeter. 3.6 differential scanning calorimeter device in which the difference in energy input into a test piece and into a calibrant may be measured as a function of temperature whil
29、e subjected to a temperature controlled heating or cooling schedule. This difference is related to the difference in heat capacity between the test piece and the calibrant. 4 Method A Drop calorimetry 4.1 General This method may be used for measurements up to a temperature of 2000 C. 4.2 Principle A
30、 test piece, sealed in a crucible where necessary, is heated to the required temperature suspended in a vertical tube furnace positioned above a receiving calorimeter. A shutter prevents radiative heat from the furnace from reaching the calorimeter. The calorimeter may be any suitable device for rec
31、ording the total amount of heat extracted from the test piece to cool it to the ambient temperature. The test piece, or crucible containing the test piece, is allowed to drop through the shutter into the calorimeter. The response of the calorimeter is monitored continuously. The output curve is anal
32、ysed, incorporating the calibrated response of the calorimeter and of the crucible if used, and the mean specific heat capacity is calculated. NOTE Using several determinations of p over different temperature ranges, the true c p at temperature T can be estimated by curve-fitting routines (see 4.6).
33、 Adherence to the procedure described below should provide results with an accuracy of better than 5% up to 1600 C. EN 821-3:2005 (E) 6 4.3 Apparatus 4.3.1 A vertical tube furnace of suitable design and maximum temperature capability is controlled by a Pt/Pt 13 % Rh or Pt/Pt 10 % Rh thermocouple (fo
34、r temperatures to 1650 C) or other suitable type (for higher temperatures) connected to a temperature controller capable of maintaining a given temperature to a constancy of 1 C. The temperature profile of the furnace shall be such as to contain a section of at least twice the length of the crucible
35、 or test piece which is at constant temperature to within 0,5 C (see 4.4). A capability for operating with an inert atmosphere is required for the testing of non-oxide materials at elevated temperatures. 4.3.2 The calorimeter may comprise any suitable device for receiving the hot test piece and for
36、recording the total heat transmitted to it from the test piece. An example based on a massive copper block is shown in Figure 1. Other examples include an ice calorimeter in which the heat transmitted is recorded as the melting of ice through the volume decrease incurred, observed using a capillary
37、level indicator. NOTE A simple water immersion calorimeter is not recommended for initial test piece temperatures above 100 C. Whichever type is employed, it shall be capable of calibration using reference materials or a known amount of electrical power. In the example of a massive copper block, the
38、 tapered central hole is designed to mate with the crucible or test piece to provide intimate thermal contact. The block contains a resistance heater and a platinum resistance thermometer. It is supported on three adjustable locating pins incorporating thermally insulating sections. 4.3.3 The calori
39、meter is placed inside a vessel in a temperature-controlled environment, such as an oil bath as shown in Figure 2. The temperature of the environment shall be constant to within 0,1 C over periods of 15 min. 4.3.4 The test piece shall be either a solid test sample of size and shape appropriate to th
40、e calorimeter, or shall comprise fragments or a powder. It may be either: a) enclosed in a platinum crucible with a tight-fitting or sealed lid, with geometry suitable for making intimate thermal contact with the calorimeter, and with the capability of being sealed and suspended by a platinum wire (
41、all samples); or b) in a form capable of having a platinum suspension wire attached at its upper end (solid samples only). NOTE The use of a crucible enables the test to be employed on powdered samples, which is especially advantageous for calibration purposes using a reference powder. 4.3.5 There s
42、hall be an arrangement whereby either the crucible or the test piece (depending upon the design and operation of the apparatus) suspended in the furnace may be dropped through a radiation screen, such as a shutter mechanism timed to open for the passage of the test piece and to close after its passa
43、ge. NOTE This minimizes the heat flux directly radiated from the hot furnace to the calorimeter. 4.3.6 A balance is required to weigh the test piece to the nearest 0,001 g. 4.4 Temperature measurement and calibration 4.4.1 For furnace temperatures below 1650 C, the initial temperature of the test pi
44、ece in the furnace shall be measured by a Pt/Pt 13 % Rh (Type R) or Pt/Pt 10 % Rh (Type S) thermocouple with a tolerance conforming to EN 60584-2, allowing use of the reference tables in EN 60584-1, or alternatively calibrated in a manner traceable to the International Temperature Scale. For furnace
45、 temperatures above 1650 C, an alternative thermocouple type shall be required. EN 821-3:2005 (E) 7 A thermocouple shall be sited with its junction on the inside of the furnace tube in order to record furnace wall temperature. A similar thermocouple shall be placed inside a platinum capsule or a dum
46、my test piece. The furnace wall temperature shall be allowed to equilibriate for at least 15 min. The capsule or dummy test piece shall then be raised or lowered through the thermal centre of the furnace in steps of not more than 10 mm in order to plot the temperature distribution. This procedure is
47、 used to establish the optimum position of the capsule or test piece in the furnace and to calibrate the difference between capsule or test piece and the furnace wall. This calibration is performed at a series of temperatures at intervals not exceeding 100 C up to the maximum furnace temperature, an
48、d is used as an indirect measure of initial test piece temperature. 4.4.2 The procedure for a massive copper block calorimeter or similar device in which a temperature rise is recorded is as follows. The calorimeter temperature is measured using a platinum resistance thermometer (PRT) connected into
49、 an a.c. bridge circuit, on the opposite arm of which is a matching standard resistor kept at a known stabilized temperature 0,1 C, which may conveniently be the temperature of the controlled environment. In order to calibrate the calorimeter, a known electrical power is dissipated in the heating resistor for a known time period, t, determined either using a stopwatch or other calibrated timing device. The output of the a.c. bridge is monitored continuously and
