ASTM C1494-13(2018)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: C1494 − 13 (Reapproved 2018)
Standard Test Methods for
Determination of Mass Fraction of Carbon, Nitrogen, and
Oxygen in Silicon Nitride Powder
This standard is issued under the fixed designation C1494; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope E50 Practices for Apparatus, Reagents, and Safety Consid-
erations for Chemical Analysis of Metals, Ores, and
1.1 These test methods cover the determination of mass
Related Materials
fraction % of carbon, nitrogen, and oxygen in silicon nitride
E1019 Test Methods for Determination of Carbon, Sulfur,
powder having chemical compositions within the following
Nitrogen, and Oxygen in Steel, Iron, Nickel, and Cobalt
limits:
Alloys by Various Combustion and Inert Gas Fusion
Element Mass Fraction % Range
Techniques
Carbon 0.05 to 5.0
Nitrogen 30 to 45 E1806 Practice for Sampling Steel and Iron for Determina-
Oxygen 0.1 to 1.5
tion of Chemical Composition
1.2 Two test methods appear in this standard.
3. Significance and Use
1.2.1 Total Carbon by the Direct Combustion-Infrared Mea-
surement Method.
3.1 Thesetestmethodsareforthechemicalanalysisofmass
1.2.2 Nitrogen by the Inert Gas Fusion-Thermal Conductiv-
fraction of carbon, nitrogen, and oxygen in silicon nitride
ity Measurement Method and Oxygen by the Inert Gas
powder. They are used in research, development, production,
Fusion-Infrared Measurement Method.
acceptance, and quality control of silicon nitride powders used
1.3 This standard does not purport to address all of the to produce ceramic components with silicon nitride content.
safety concerns, if any, associated with its use. It is the
3.2 It is assumed that all who use these test methods will be
responsibility of the user of this standard to establish appro-
trained analysts capable of performing common laboratory
priate safety, health, and environmental practices and deter-
proceduresskillfullyandsafely.Itisexpectedthatworkwillbe
mine the applicability of regulatory limitations prior to use.
performed in a properly equipped laboratory.
Specific hazard statements are given in Section 6.
1.4 This international standard was developed in accor-
4. Apparatus and Reagents
dance with internationally recognized principles on standard-
4.1 The procedure was written with commercial carbon and
ization established in the Decision on Principles for the
nitrogen/oxygen analyzers in mind. For any other analyzer, the
Development of International Standards, Guides and Recom-
instrument manual specific to that analyzer shall be consulted
mendations issued by the World Trade Organization Technical
for instrument set-up.
Barriers to Trade (TBT) Committee.
4.2 Specific apparatus and reagents required for each deter-
mination are listed in separate sections preceding the proce-
2. Referenced Documents
dure.
2.1 ASTM Standards:
E29 Practice for Using Significant Digits in Test Data to
5. Sampling
Determine Conformance with Specifications
5.1 Procedures for sampling the materials refer to those
parts of Practice E1806 pertaining to solid-form samples of the
type used for instrumental analysis.
These test methods are under the jurisdiction of ASTM Committee C28 on
Advanced Ceramics and are the direct responsibility of Subcommittee C28.03 on
6. Hazards
Physical Properties and Non-Destructive Evaluation.
Current edition approved Oct. 1, 2018. Published October 2018. Originally
6.1 For hazards to be observed in the use of certain reagents
approved in 2001. Last previous edition approved in 2013 as C1494 – 13. DOI:
in this test method, refer to Practices E50.
10.1520/C1494-13R18.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
6.2 Use care when handling hot crucibles and operating
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
furnaces to avoid personal injury by either burn or electrical
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. shock.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1494 − 13 (2018)
7. Total Carbon in Silicon Nitride Powder by Direct 7.6.3 Determine the instrument blank.
Combustion – Infrared Detection Method (a) Enter 1.000 g weight into weight stack.
(b) Add 1.000 g (60.005 g) of tungsten/tin accelerator and
7.1 Scope—This test method covers the determination of
1.000 g (60.005 g) of iron chip accelerator.
carbon in concentrations from 0.05 to 5.0 % mass fraction.
(c) Place crucible on furnace pedestal and analyze.
7.2 Summary of Test Method —The carbon is converted to
(d) Repeat steps 7.6.3(a) through 7.6.3(c) a minimum of
carbon dioxide by combustion in a stream of oxygen. The
three times.
amount of carbon dioxide is measured by infrared (IR)
(e) Enter blank value following routine outlined in opera-
absorption.
tor’s instruction manual.
7.3 Apparatus—This test method is written for use with
7.7 Instrument Calibration Procedure:
commercial carbon analyzers, equipped to carry out the analy-
7.7.1 This procedure was written specially for a carbon
ses operations automatically and calibrated using steel stan-
analyzer.Thetypeandamountsofacceleratortobeaddedshall
dards with known concentrations of carbon. The operating
be adjusted according to the manufacturer’s recommendations
principles, specifications, and descriptions of commercial car-
for the other instrumentation.
bon analyzers are given in Test Methods E1019.
7.7.2 Weigh 0.1 to 0.5 g of calibration standard to the
nearest mg into a prebaked ceramic or similar refractory
7.4 Reagents and Materials:
7.4.1 Crucibles—Expendable ceramic (alumina) or similar crucible and enter appropriate weight into weight stack.
7.7.3 Add approximately 1.0 6 0.005 g of tungsten/tin
refractory crucibles as specified by commercial carbon analyz-
ers’ manufacturers. Both the crucible and cover, if used, must accelerator and approximately 1.0 6 0.005 g of iron chips
accelerator.
be prebaked for a sufficient time to produce constant blank
values. Use the prebake schedule recommended by the instru- 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
ment manufacturer.
7.4.2 Crucible Tongs—Capable of handling recommended three times for each standard, and calibrate the instrument
following the autocalibration procedure as outlined in the
crucibles with respect to their sizes, shape, and temperature.
7.4.3 Accelerators—Carbon-free (or containing a known operator’s instruction manual.
7.7.6 Check calibration by analyzing the calibration stan-
amount of carbon) granular tungsten/tin and iron chip accel-
erators shall be used. dard again if it is not within the reported range. If it is not,
repeat steps 7.7.2 – 7.7.4.
7.4.4 Carbon Standard Reference Materials—NIST SRM
8k (steel—0.0806 % C mass fraction), NIST SRM 19h
7.8 Sample Analysis Procedure:
(steel—0.215 % C mass fraction), NIST SRM 12h (steel—
7.8.1 Weigh 0.1 to 0.5 g of sample to the nearest mg into a
0.407 % C mass fraction), and NIST RM 8983 (silicon
prebaked expendable ceramic or a similar refractory crucible
nitride—0.107 % C mass fraction).
and add appropriate weight to the weight stack.
7.4.5 Oxygen—Ultra high purity (99.95 % minimum purity)
7.8.2 Repeat steps 7.7.3 and 7.7.4 in the calibration proce-
or regular grade (99.5 %) purified by passing over heated CuO
dure.
and through CO /H O absorbents. (When the instrument has a
2 2
7.8.3 Each sample shall be analyzed in triplicate and record
built-in purifier, regular grade oxygen can be used.)
the integral values of the sample.
7.5 Preparation of Apparatus—Follow the operating in-
7.9 Calculation—Most commercially available instruments
structions for the specific equipment used. After having prop-
calculate percent concentration directly. If the instrument does
erly set the operating controls of the instrument system,
not give percent concentration, please follow the manufactur-
condition the apparatus by combustion of several blanks
er’s directions to ensure all the essential variables in the
prepared with sample crucible and accelerator in the amounts
calculation of analysis results have been included.
to be used with the test specimen analyses. Successive blanks
Or perform the following calculation to determine percent
should achieve a steady-state value.
concentration (% mass):
7.6 Blank Determination: 7.9.1 Calibration constant:
7.6.1 Prebake ceramic crucibles in a muffle or tube furnace
G 3P/100
K 5 (1)
at 1250 °C for not less than 15 min or at 1000 °C for not less
A 2 A
c b
than 40 min. The crucibles shall be removed from the furnace,
where:
allowed to cool for 1 to 2 min, and placed in a desiccator for
K = calibration constant (g/integral value),
storage. If the crucibles are not used within four hours, they
G = mass of calibration sample (g),
must be prebaked again. This prebaking procedure is to burn
P = total carbon content of the calibration sample (%
off any organic contaminates.
mass),
7.6.2 Prepare instrument as outlined in the operator’s in-
A = integral value of the calibration sample (7.7.6), and
struction manual. c
The test method procedure was adapted from (a) Test Methods E1019-94,
“Standard Test Methods for Determination of C, S, N, and O in Iron, Nickel and The weight of sample is chosen based on the expected amount of carbon
Cobalt Alloys” and (b) Application Bulletin: “Carbon and Sulfur in Ceramic and present and so the CO produced will fall within the detection range of the IR
Similar Materials,” LECO Corp., St. Joseph, MI. detector.
C1494 − 13 (2018)
8. Determination of Total Nitrogen in Silicon Nitride
A = integral value of the blank (7.6.3(e)).
b
Powder by Direct Inert Gas Fusion-Thermal
7.9.2 Total carbon content:
Conductivity Method and Oxygen by the Inert Gas
A 2 A 3K 3100
~ !
s b Fusion-Infrared Measurement Method
C 5 (2)
m
8.1 Scope—This test method covers the determination of
where: nitrogen (N) in concentrations from 30 to 45 % mass fraction.
This test method also covers the determination of oxygen (O)
C = carbon content (mass %),
in concentrations from 0.1 to 1.5 % mass fraction.
A = integral value of the sample (7.8.3),
s
A = integral value of the blank (7.6.3(e)),
b
8.2 Summary of Test Method—A pre-weighed sample is
K = calibration constant (g/integral value), and
placed in a single-use graphite crucible which is then resis-
m = mass of the sample (g).
tively heated in an electrode furnace under an inert atmosphere
7.10 Report—Report carbon concentration as mass fraction
to release analyte gases. An inert gas carrier, typically helium,
percentage to the desired decimal places as directed in Practice
sweeps the liberated analyte gases out of the furnace and
E29, as well as times of replication of analysis and any through a series of detectors. During heating, nitrogen and
deviations from the standard analysis procedure.
hydrogen present in the sample are released into the carrier
stream. Oxygen present in the sample reacts with the graphite
7.11 Precision and Bias:
crucible to form CO and CO . The gas mixture then flows
7.11.1 Precision:
through a heated reagent, where the CO is oxidized to form
7.11.1.1 Reproducibility—Three laboratories cooperated in
CO,H is oxidized to form H O; N passes unchanged. The
2 2 2 2
testing this method and obtained reproducibility data for SRM
gas mixture then continues through a set of infrared dectection
8j, 11h, and 12h which are summarized in Table 1. Since the
cells where CO and H O are measured. The CO and H O
2 2 2 2
reference value with uncertainty of RM 8983 is determined
analytes are then scrubbed out of the carrier gas stream leaving
during this round robin study, no reproducibility is reported.
only N and carrier. The final component in the system is a
7.11.1.2 Repeatability—Three laboratories cooperated in
thermal conductivity (TC) detector which is used to measure
testing this method and obtained repeatability data for SRM 8j,
nitrogen.
11h, and 12h which are summarized in Table 1. Since the
reference value with uncertainty of RM 8983 is determined 8.3 Apparatus—This test method is written for use with
during this round robin study, no repeatability is reported.
commercial nitrogen/oxygen analyzers, equipped to carry out
7.11.2 Bias—No bias of this test method is established, the analyses operation automatically and calibrated using
since insufficient number of laboratories have participated this
standardswithknownmassfraction%ofnitrogen/oxygen.The
round robin study.The accuracy of a reading may be judged by
operating principles, specifications, and descriptions of com-
comparingvaluesobtainedwithNISTreferencestandardssuch
mercial nitrogen/oxygen analyzers are given in Test Methods
as listed in Table 1 to their reference values and uncertainty.
E1019.
8.4 Reagents and Materials:
8.4.1 Graphite Crucible, (resistance heated and sacrificial)
TABLE 1 Statistical Information for Carbon Analysis (Mass
as recommended by the manufacturer of the instrument.
Fraction %)
8.4.2 Crucible Tongs, capable of handling recommended
Carbon
crucibles and capsules with respect to their sizes, shape, and
Test Repeatability Reproducibility
Reference Found
A B
Specimen Limit Limit
temperature.
Value
8.4.3 TinCapsules, as recommended by the manufacturer of
Bessemer Steel 0.081 ± 0.0796 0.0089 0.0066
C
the instrument.
(NIST SRM 8j) 0.001
Open-Hearth Steel 0.200 ± 0.2038 0.0022 0.0126
8.4.4 Nickel Baskets (Flux), as recommended by the instru-
D
(NIST SRM 11h) 0.001
ment manufacturer.
Open-Hearth Steel 0.407 ± 0.4211 0.0055 0.0383
E
(NIST SRM 12h) 0.003 8.4.5 Inert Gas (Commonly Helium)—Use type and purity
Silicon Nitride 0.107 ± . . .
specified by the instrument manufacturer.
F
(NIST RM 8983) 0.015
8.4.6 Calibration Standards:
A
The 95 % repeatability limit is defined as 1.96* U which is the
repeatability
8.4.6.1 Oxygen—Select standards with appropriate concen-
uncertainty of a difference of two averages, each based on three repeated
measurements at one laboratory. This U is also called repeatability trations.
repeatability
standard deviation.
8.4.6.2 Nitrogen—Select standards with appropriate con-
B
The 95 % reproducibility limit is defined as 1.96* U which is the
reproducibility
centrations.
uncertainty of a difference of two averages, each of wh
...