1、Designation: C1494 01 (Reapproved 2007)C1494 13Standard Test Methods forDetermination of Mass Fraction of Carbon, Nitrogen, andOxygen in Silicon Nitride Powder1This standard is issued under the fixed designation C1494; the number immediately following the designation indicates the year oforiginal ad
2、option or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 These test methods cover the determination of mass fraction % of carbo
3、n, nitrogen and oxygen in silicon nitride powderhaving chemical compositions within the following limits:Element Mass Fraction % RangeCarbon 0.05 to 5.0Nitrogen 30 to 45Oxygen 0.1 to 1.51.2 Two test methods appear in this standard.1.2.1 Total Carbon by the Direct Combustion-Infrared Measurement Meth
4、od.1.2.2 Nitrogen and oxygen by the Inert Gas Fusion-Thermal Conductivity Measurement Method and Oxygen by the Inert GasFusion-Infrared Measurement Method.1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of
5、 this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. Specific hazard statements are given in Section 6.2. Referenced Documents2.1 ASTM Standards:2E29 Practice for Using Significant Digits in Test Data to Determine
6、Conformance with SpecificationsE50 Practices forApparatus, Reagents, and Safety Considerations for ChemicalAnalysis of Metals, Ores, and Related MaterialsE1019 Test Methods for Determination of Carbon, Sulfur, Nitrogen, and Oxygen in Steel, Iron, Nickel, and Cobalt Alloys byVarious Combustion and Fu
7、sion TechniquesE1409 Test Method for Determination of Oxygen and Nitrogen in Titanium and Titanium Alloys by Inert Gas FusionE1569 Test Method for Determination of Oxygen in Tantalum Powder by Inert Gas Fusion TechniqueE1806 Practice for Sampling Steel and Iron for Determination of Chemical Composit
8、ionE1941 Test Method for Determination of Carbon in Refractory and Reactive Metals and Their Alloys by Combustion Analysis3. Significance and Use3.1 These test methods are for the chemical analysis of mass fraction of carbon, nitrogen and oxygen in silicon nitride powder.They are used in research, d
9、evelopment, production, acceptance, and quality control of silicon nitride powders used to produceceramic components with silicon nitride content.3.2 These test methods are for the chemical analysis of mass fraction of carbon, nitrogen and oxygen in silicon nitride powder.It is assumed that all who
10、use these test methods will be trained analysts, capable of performing common laboratory proceduresskillfully and safely. It is expected that work will be performed in a properly equipped laboratory.4. Apparatus and Reagents4.1 The procedure was written with commercial carbon and nitrogen/oxygen ana
11、lyzers in mind. For any other analyzer, theinstrument manual specific to that analyzer shall be consulted for instrument set-up.1 These test methods are under the jurisdiction of ASTM Committee C28 on Advanced Ceramics and are the direct responsibility of Subcommittee C28.03 on PhysicalProperties an
12、d Non-Destructive Evaluation.Current edition approved Nov. 1, 2007Aug. 1, 2013. Published December 2007January 2014. Originally approved in 2001. Last previous edition approved in 20012007as C1494 01.C1494 01 (2007). DOI: 10.1520/C1494-01R07.10.1520/C1494-13.2 For referencedASTM standards, visit the
13、ASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an
14、indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to
15、be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.2 Specific apparatus and reagents required for each determination are listed in separate sections preceding the procedure .5. Sampling5.1 Procedures
16、 for sampling the materials refer to those parts of Practice E1806 pertaining to solid form samples of the typeused for instrumental analysis.6. Hazards6.1 For hazards to be observed in the use of certain reagents in this test method, refer to Practice E50.6.2 Use care when handling hot crucibles an
17、d operating furnaces to avoid personal injury by either burn or electrical shock.7. Total Carbon in Silicon Nitride Powder by Direct CombustionInfrared Detection Method7.1 ScopeThis test method covers the determination of carbon in concentrations from 0.05 to 5.0 % mass fraction.7.2 Summary of Test
18、Method3The carbon is converted to carbon dioxide by combustion in a stream of oxygen. The amountof carbon dioxide is measured by infrared (IR) absorption.7.3 ApparatusThis test method is written for use with commercial carbon analyzers, equipped to carry out the analysesoperations automatically and
19、calibrated using steel standards with known concentrations of carbon. The operating principles,specifications and descriptions of commercial carbon analyzers are given in the Practice of E1019.7.4 Reagents and Materials:7.4.1 CruciblesExpendable ceramic (alumina) or similar refractory crucibles as s
20、pecified by commercial carbon analyzersmanufacturers. Both the crucible and cover, if used, must be prebaked for a sufficient time to produce constant blank values. Usethe prebake schedule recommended by the instrument manufacturer.7.4.2 Crucible TongsCapable of handling recommended crucibles with r
21、espect to their sizes, shape and temperature.7.4.3 AcceleratorsCarbon free (or containing a known amount of carbon) granular tungsten/tin and iron chip accelerators shallbe used.7.4.4 Carbon Standard MaterialReference MaterialsNISTSRM 8j (0.081 %C), SRM 1 lh (0.2 %C), SRM 12h (0.407 %C),8k (steel -
22、0.0806 % C mass fraction), NIST SRM 19h (steel - 0.215 % C mass fraction), NIST SRM 12h (steel - 0.407 % C massfraction), and NIST RM 8983 (0.107 %C).(silicon nitride - 0.107 % C mass fraction).7.4.5 OxygenUltra High Purity (99.95 % minimum purity) or Regular grade (99.5 %) purified by passing over
23、heated CuOand through CO2/H20O absorbents. (When the instrument has a built in purifier, regular grade oxygen can be used.)7.5 Preparation of ApparatusFollow the operating instructions for the specific equipment used. After having properly set theoperating controls of the instrument system, conditio
24、n the apparatus by combustion of several blanks prepared with sample crucibleand accelerator in the amounts to be used with the test specimen analyses. Successive blanks should achieve a steady state value.7.6 Blank Determination:7.6.1 Prebake ceramic crucibles in a muffle or tube furnace at 1350125
25、0 C for not less than 15 min or at 1000 C for not lessthan 40 minutes. The crucibles shall be removed from the furnace, allowed to cool for 1-2 min and placed in a desiccator forstorage. If the crucibles are not used within four hours, they must be prebaked again. This prebaking procedure is to burn
26、 off anyorganic contaminates.7.6.2 Prepare instrument as outlined in the operators instruction manual.7.6.3 Determine the instrument blank.(a) Enter 1.000 g weight into weight stack.(b) Add 1.000 g (6 0.005 g) of tungsten/tin accelerator and 1.000 g (6 0.005 g) of iron chip accelerator.(c) Place cru
27、cible on furnace pedestal and analyze.(d) Repeat steps 7.6.3a through 7.6.3c a minimum of three times.(e) Enter blank value following routine outlined in operators instruction manual.7.7 Instrument Calibration Procedure :7.7.1 This procedure was written specially for a carbon analyzer. The type and
28、amounts of accelerator to be added shall beadjusted according to the manufacturers recommendations for the other instrumentation.7.7.2 Weigh 0.1 to 0.5 g of calibration standard to the nearest mg into a prebaked ceramic or similar refractory crucible and enterappropriate weight into weight stack.7.7
29、.3 Add approx. 1.0 6 0.005 g of tungsten/tin accelerator and approx. 1.0 6 0.005 g of iron chips accelerator.7.7.4 Place crucible on pedestal and analyze.7.7.5 Repeat the above steps 7.7.2 7.7.4 a minimum of three times for each standard, and calibrate the instrument followingthe auto calibration pr
30、ocedure as outlined in the operators instruction manual.3 The test method procedure was adapted from (a) ASTM E1019-94 , “Standard Test Methods for Determination of C, S, N, and O in Iron, Nickel and Cobalt Alloys”and ( b) Application Bulletin: “Carbon and Sulfur in Ceramic and Similar Materials,” L
31、ECO Corp., St. Joseph, MI.C1494 1327.7.6 Check calibration by analyzing the calibration standard again if it is not within the reported range. If it is not, repeat steps7.7.2 7.7.4.7.8 Sample Analysis Procedure:7.8.1 Weigh 0.1 to 0.5 g of sample to the nearest mg into a prebaked expendable ceramic o
32、r a similar refractory crucible andadd appropriate weight to the weight stack.47.8.2 Repeat steps 7.7.3 and 7.7.4 in the calibration procedure.7.8.3 Each sample shall be analyzed in triplicate and record the integral values of the sample.7.9 CalculationMost commercially available instruments calcula
33、te percent concentration directly. If the instrument does notgive percent concentration, please follow the manufacturers directions to ensure all the essential variables in the calculation ofanalysis results have been included.Or perform the following calculation to determine percent concentration (
34、% mass):a. Calibration Constant:K 5G 3P/100Ac 2Ab(1)where:K = calibration constant (g/integral value),G = mass of calibration sample (g),P = total carbon content of the calibration sample (% mass),Ac = integral value of the calibration sample (7.7.6), andAb = integral value of the blank (7.6.3e).b.
35、Total Carbon Content:C 5As 2Ab!3K 3100m (2)where:C = carbon content (mass %),As = integral value of the sample (7.8.3),Ab = integral value of the blank (7.6.3e),K = calibration constant (g/integral value), andm = mass of the sample (g).7.10 ReportReport carbon concentration as mass fraction percenta
36、ge to the desired decimal places as directed in Practice E29,as well as times of replication of analysis and any deviations from the standard analysis procedure.7.11 Precision and Bias:7.11.1 Precision:7.11.1.1 ReproducibilityThree laboratories cooperated in testing this method and obtained reproduc
37、ibility data for SRM 8j, 1lh, 11h, and 12h which are summarized in Table 1. Since the reference value with uncertainty of RM 8983 is determined duringthis round robin study, no reproducibility is reported.7.11.1.2 RepeatabilityThree laboratories cooperated in testing this method and obtained repeata
38、bility data for SRM 8j, 1 lh11h and 12h which are summarized in Table 1. Since the reference value with uncertainty of RM 8983 is determined during thisround robin study, no repeatability is reported.7.11.2 BiasNo bias of this test method is established, since insufficient number of laboratories hav
39、e participated this roundrobin study. The accuracy of a reading may be judged by comparing values obtained with NIST reference standards such as listedin Table 1 to their reference values and uncertainty.8. Determination of Total Nitrogen and Oxygen in Silicon Nitride Powder by Direct Inert Gas Fusi
40、on-ThermalConductivity Method and Oxygen by the Inert Gas Fusion-Infrared Measurement Method8.1 ScopeThis test method covers the determination of nitrogen (N) in concentrations from 30 to 45 % mass fraction. Thistest method also covers the determination of oxygen (O) in concentrations from 0.1 to 1.
41、5 % mass fraction.8.2 Summary of Test MethodMethodThe specimen, contained - A pre-weighed sample is placed in a small single-usegraphite crucible, is fused under a flowing helium atmosphere at a minimum temperature of 1900 C which is sufficient to releaseoxygen, nitrogen and hydrogen from the sample
42、. The oxygen combines with carbon from the crucible to form carbon monoxide(CO) which is carried by the helium inert gas stream to a thermal conductivity (TC) detector. Nitrogen single-use graphite cruciblewhich is then resistively heated in an electrode furnace under an inert atmosphere to release
43、analyte gases. An inert gas carrier,4 The weight of sample is chosen based on the expected amount of carbon present and so the CO2 produced will fall within the detection range of the IR detector.C1494 133typically helium, sweeps the liberated analyte gases out of the furnace and through a series of
44、 detectors. During heating, nitrogenand hydrogen present in the sample are released into the carrier stream. Oxygen present in the sample reacts with the graphitecrucible to form CO and CO2is released as molecular nitrogen. The gas mixture then flows through a heated reagent, where theCO is oxidized
45、 to form CO2 into, H2 is oxidized to form H2O; N2 passes unchanged. The gas mixture then continues through aset of infrared dectection cells where CO2 and H2O are measured. The CO2 and H2the flowing helium stream. O analytes are thenscrubbed out of the carrier gas stream leaving only N2The nitrogen
46、is separated from other liberated gases such as hydrogen andcarbon monoxide and is finally measured in a thermal conductivity cell. and carrier. The final component in the system is a ThermalConductivity (TC) detector which is used to measure nitrogen.8.3 ApparatusThis test method is written for use
47、 with commercial nitrogen/oxygen analyzers, equipped to carry out theanalyses operation automatically and calibrated using standards with known mass fraction % of nitrogen/oxygen. The operatingprinciples, specifications and descriptions of commercial nitrogen/oxygen analyzers are given in the Practi
48、ce of E1019.8.4 Reagents and Materials:8.4.1 High Temperature Graphite Crucible, (resistance heated) heated and sacrificial) as recommended by the manufacturer ofthe instrument.8.4.2 Graphite Crucible (sacrificial heated) as recommended by the instrument manufacturer.8.4.2 Crucible Tongs, capable of
49、 handling recommended crucibles and capsules with respect to their sizes, shape andtemperature.8.4.3 Tin Capsules, as recommended by the manufacturer of the instrument.8.4.4 Nickel Baskets (Flux)(Flux), as recommended by the instrument manufacturer.8.4.5 Inert Gases (Helium, Compressed Air, Nitrogen or Argon)Gas (commonly Helium)Use type and purity specified bythe instrument manufacturer.8.4.6 Calibration Standards:8.4.6.1 OxygenSelect standards with appropriate concentrations.8.4.6.2 NitrogenSelect standards with appropriate concentration
