ASTM C1274-12(2020)

Standard Test Method for Advanced Ceramic Specific Surface Area by Physical Adsorption

SIGNIFICANCE AND USE
5.1 Advanced ceramic powders and porous ceramic bodies often have a very fine particulate morphology and structure that are marked by high surface-to-volume (S-V) ratios. These ceramics with high S-V ratios commonly exhibit enhanced chemical reactivity and lower sintering temperatures. Results of many intermediate and final ceramic processing steps are controlled by, or related to, the specific surface area of the advanced ceramic. The functionality of ceramic adsorbents, separation filters and membranes, catalysts, chromatographic carriers, coatings, and pigments often depends on the amount and distribution of the porosity and its resulting effect on the specific surface area.  
5.2 This test method determines the specific surface area of advanced ceramic powders and porous bodies. Both suppliers and users of advanced ceramics can use knowledge of the surface area of these ceramics for material development and comparison, product characterization, design data, quality control, and engineering/ production specifications.
SCOPE
1.1 This test method covers the determination of the surface area of advanced ceramic materials (in a solid form) based on multilayer physisorption of gas in accordance with the method of Brunauer, Emmett, and Teller (BET) (1)2 and based on IUPAC Recommendations (1984 and 1994) (2, 3). This test method specifies general procedures that are applicable to many commercial physical adsorption instruments. This test method provides specific sample outgassing procedures for selected common ceramic materials, including: amorphous and crystalline silicas, TiO2, kaolin, silicon nitride, silicon carbide, zirconium oxide, etc. The multipoint BET (1) equation along with the single-point approximation of the BET equation are the basis for all calculations. This test method is appropriate for measuring surface areas of advanced ceramic powders down to at least 0.05 m2 (if in addition to nitrogen, krypton at 77.35 K is utilized as an adsorptive).  
1.2 This test method does not include all existing procedures appropriate for outgassing of advanced ceramic materials. However, it provides a comprehensive summary of procedures recommended in the literature for selected types of ceramic materials. The investigator shall determine the appropriateness of listed procedures.  
1.3 The values stated in SI units are to be regarded as standard. State all numerical values in terms of SI units unless specific instrumentation software reports surface area using alternate units. In this case, provide both reported and equivalent SI units in the final written report. It is commonly accepted and customary (in physical adsorption and related fields) to report the (specific) surface area of solids as m2/g and, as a convention, many instruments (as well as certificates of reference materials) report surface area as m2 g–1, instead of using SI units (m2 kg–1).  
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.5 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.

General Information

• Status: Published
• Publication Date: 31-Mar-2020
• ICS: 81.060.99 - Other standards related to ceramics
• Technical Committee: C28 - Advanced Ceramics
• Drafting Committee: C28.03 - Physical Properties and Non-Destructive Evaluation

Relations

• Replaces: ASTM C1274-12 - Standard Test Method for Advanced Ceramic Specific Surface Area by Physical Adsorption
• Effective Date: 01-Apr-2020
• Refers: ASTM E177-14 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2014
• Refers: ASTM E177-13 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-May-2013
• Refers: ASTM E177-10 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Oct-2010
• Refers: ASTM E177-08 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Oct-2008
• Refers: ASTM E177-06b - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 15-Nov-2006
• Refers: ASTM E177-06a - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Nov-2006
• Refers: ASTM E177-06 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Nov-2004
• Refers: ASTM E177-04e1 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Nov-2004
• Refers: ASTM E177-04 - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 01-Nov-2004
• Refers: ASTM E177-90a(2002) - Standard Practice for Use of the Terms Precision and Bias in ASTM Test Methods
• Effective Date: 10-Jan-2002
• Referred By: ASTM D8325-20 - Standard Guide for Evaluation of Nuclear Graphite Surface Area and Porosity by Gas Adsorption Measurements
• Effective Date: 01-Apr-2020
• Referred By: ASTM C757-16(2021) - Standard Specification for Nuclear-Grade Plutonium Dioxide Powder for Light Water Reactors
• Effective Date: 01-Apr-2020
• Referred By: ASTM C781-20 - Standard Practice for Testing Graphite Materials for Gas-Cooled Nuclear Reactor Components
• Effective Date: 01-Apr-2020
• Referred By: ASTM C1793-15 - Standard Guide for Development of Specifications for Fiber Reinforced Silicon Carbide-Silicon Carbide Composite Structures for Nuclear Applications
• Effective Date: 01-Apr-2020

Standards Content (Sample)

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:C1274 −12 (Reapproved 2020)
Standard Test Method for
Advanced Ceramic Specific Surface Area by Physical
Adsorption
This standard is issued under the fixed designation C1274; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope convention, many instruments (as well as certificates of refer-
2 –1
ence materials) report surface area as m g , instead of using
1.1 Thistestmethodcoversthedeterminationofthesurface
2 –1
SI units (m kg ).
area of advanced ceramic materials (in a solid form) based on
1.4 This standard does not purport to address all of the
multilayer physisorption of gas in accordance with the method
safety concerns, if any, associated with its use. It is the
of Brunauer, Emmett, and Teller (BET) (1) and based on
responsibility of the user of this standard to establish appro-
IUPAC Recommendations (1984 and 1994) (2, 3). This test
priate safety, health, and environmental practices and deter-
method specifies general procedures that are applicable to
mine the applicability of regulatory limitations prior to use.
many commercial physical adsorption instruments. This test
1.5 This international standard was developed in accor-
method provides specific sample outgassing procedures for
dance with internationally recognized principles on standard-
selectedcommonceramicmaterials,including:amorphousand
ization established in the Decision on Principles for the
crystalline silicas, TiO , kaolin, silicon nitride, silicon carbide,
Development of International Standards, Guides and Recom-
zirconium oxide, etc. The multipoint BET (1) equation along
mendations issued by the World Trade Organization Technical
with the single-point approximation of the BET equation are
Barriers to Trade (TBT) Committee.
thebasisforallcalculations.Thistestmethodisappropriatefor
measuringsurfaceareasofadvancedceramicpowdersdownto
2. Referenced Documents
at least 0.05 m (if in addition to nitrogen, krypton at 77.35 K
is utilized as an adsorptive). 2.1 ASTM Standards:
D1993Test Method for Precipitated Silica-Surface Area by
1.2 This test method does not include all existing proce-
Multipoint BET Nitrogen Adsorption
dures appropriate for outgassing of advanced ceramic materi-
E177Practice for Use of the Terms Precision and Bias in
als. However, it provides a comprehensive summary of proce-
ASTM Test Methods
dures recommended in the literature for selected types of
2.2 ISO Standards:
ceramic materials. The investigator shall determine the appro-
ISO 9277Determination of Specific Surface Area of Solids
priateness of listed procedures.
by Gas Adsorption Using the BET Method
1.3 The values stated in SI units are to be regarded as
ISO 15901-2:2006Pore Size Distribution and Porosity of
standard. State all numerical values in terms of SI units unless
Solid Materials by Mercury Porosimetry and Gas
specific instrumentation software reports surface area using
Adsorption,Part2—AnalysisofMesoporesandMacropo-
alternate units. In this case, provide both reported and equiva-
res by Gas Adsorption
lentSIunitsinthefinalwrittenreport.Itiscommonlyaccepted
ISO 8213:1986Chemical Products for Industrial Use—
and customary (in physical adsorption and related fields) to
Sampling Techniques—Solid Chemical Products in the
report the (specific) surface area of solids as m /g and, as a
FormofParticlesVaryingfromPowderstoCoarseLumps
This test method is under the jurisdiction of ASTM Committee C28 on
Advanced Ceramics and is the direct responsibility of Subcommittee C28.03 on For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Physical Properties and Non-Destructive Evaluation. contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Current edition approved April 1, 2020. Published April 2020. Originally Standards volume information, refer to the standard’s Document Summary page on
approved in 1994. Last previous edition approved in 2012 as C1274–12. DOI: the ASTM website.
10.1520/C1274-12R20. Available from International Organization for Standardization (ISO), 1, ch. de
The boldface numbers in parenthesis refer to the list of references at the end of la Voie-Creuse, Case postale 56, CH-1211, Geneva 20, Switzerland, http://
this standard. www.iso.ch.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C1274−12 (2020)
ISO 18757Fine Ceramics (Advanced Ceramics, Advanced 3.1.15 surface area, specific (SSA), n—areaperunitmassof
Technical Ceramics)—Determination of Specific Surface a granular or powdered or formed porous solid of all external
Area of Ceramic Powders by Gas Adsorption Using the and internal surfaces that are accessible to a penetrating gas or
BET Method liquid.
3. Terminology 4. Summary of Test Method
3.1 Definitions:
4.1 An appropriately sized (to provide at least the minimum
3.1.1 adsorbate, n—material that has been retained by the surface area required for reliable results, refer to requirements
process of adsorption. provided by the manufacturer of the instrument or apparatus
being used) aliquot of sample is outgassed under appropriate
3.1.2 adsorbent, n—any solid having the ability to concen-
conditions prior to analysis. For details on outgassing methods
trate significant quantities of other substances on its surface.
and examples of specific outgassing conditions recommended
3.1.3 adsorption, n—process in which molecules are con-
for selected ceramic materials, see Section 11.
centrated on a surface by chemical or physical forces, or both.
4.2 The adsorptive gas is admitted to a sample container
3.1.4 adsorption isotherm, n—relation between the quantity
held at a constant temperature. The amounts adsorbed are
of adsorbate and the equilibrium (relative) pressure of the
measured in equilibrium with the adsorptive gas pressure, p,
adsorptive, at constant temperature.
and plotted against the relative pressure, p/p (where p is the
0 0
3.1.4.1 Discussion—Typically, the amount adsorbed is pre-
saturation vapor pressure), to give an adsorption isotherm.
sented on an isotherm as volume in cm STP (standard
Adsorption isotherms may be obtained by volumetric (mano-
temperature and pressure, that is, 273.15 K and 101325.02 Pa)
metric) measurements or by the carrier gas flow measurements
normalized per mass of sample.
(flowvolumetricmethod)andgravimetrictechniques.Thistest
method employs volumetric and flow volumetric methods.
3.1.5 adsorptive, n—any substance available for adsorption.
4.3 (Multipoint BET Analyses Only)—The volume of gas
3.1.6 aliquot, n—a representative portion of a whole that
adsorbed, or desorbed, is determined for a minimum of four
divides the whole, leaving a remainder.
relative pressures within the linear BET transformation range
3.1.7 molecular cross-sectional area, n—molecular area of
of the physical adsorption, or desorption, isotherm character-
the adsorbate, that is, the area occupied by an adsorbate
istic of the advanced ceramic. The linear range is that which
molecule in the completed closed-packed monolayer.
results in a least-square correlation coefficient of 0.995 (pref-
3.1.8 monolayer capacity, n—amount of the adsorbate (ex-
erably 0.999) or greater for the linear relationship (see linear
pressed as number of moles, volume at STP, or weight) that
form of BET equation, in Annex A1). Typically, the linear
forms a closed-packed (complete) monomolecular layer over
range includes relative pressures between 0.05 and 0.30 (4, 5).
the surface of the adsorbent.
However,microporousmaterialsusuallyrequireuseofarange
of lower relative pressures (often a linear BET range can be
3.1.9 outgassing, n—evolution of gas from a material under
foundintherelativepressurerangefrom0.01to0.1 (5, 6)).For
a vacuum or inert gas flow at or above ambient temperature.
details, see Annex A2.
3.1.10 physical adsorption (van der Waals adsorption),
4.4 (Single-Point BET Analyses Only)—The volume of gas
n—the binding of an adsorbate to the surface of a solid by
adsorbed, or desorbed, is determined at the highest known
forceswhoseenergylevelsapproximatethoseofcondensation.
relativepressurewithinthelinearBETtransformationrangeof
3.1.11 relative pressure, n—ratiooftheequilibriumadsorp-
the physical adsorption, or desorption, isotherm. Typically, a
tion pressure, p, to the saturation vapor pressure, p .
relativepressureof0.30isused.However,itmaybenecessary
3.1.12 saturation vapor pressure, n—vapor pressure of the
to perform a multipoint analysis of the material first to
bulk liquefied adsorbate at the temperature of adsorption.
determine the optimum single-point relative pressure.
3.1.13 surface area, n—total surface area of the surface of a
4.5 The physical adsorption instrument or apparatus mea-
powderorsolid,includingbothexternalandaccessibleinternal
sures the total amount of gas adsorbed onto, or desorbed from,
surfaces (from voids, cracks, open porosity, and fissures).
the sample under analysis. The sample mass is then used to
3.1.13.1 Discussion—Thesurfaceareamaybecalculatedby
normalize the measured results. Therefore, it is important to
the BET equation (1) from gas adsorption data obtained under
use an analytical balance to determine the sample weight. The
specific conditions. It is useful to express this value as the
mass of dry and outgassed sample, recorded to the nearest
specific surface area (see 3.1.13), that is, surface area per unit
0.1mg, shall be used. Any error in the sample weight will be
2 –1
mass of sample (m g ).
propagated into the final BET surface area result.
3.1.14 surface area (BET), n—total surface area of a solid
4.6 Typical steps involved in the evaluation of the BET
calculated by the BET equation (1) from gas adsorption or
surface area (see Annex A1 for calculation details):
desorption data obtained under specific conditions.
4.6.1 Transformation of a physisorption isotherm into the
BET plot;
4.6.2 An assessment of the monolayer capacity (multipoint
Compilation of ASTM Standard Terminology, 8th ed, 1994. orsingle-pointmethod).(SeeEqA1.1-A1.6inAnnexA1.);and
C1274−12 (2020)
NOTE1—Monolayercapacitycanbeexpressedalternativelyintermsof
6. Interferences
STP volume (V ), weight (w ), or number of moles (n ) of adsorbate in
m m m
6.1 This test method can be used to determine the internal
a complete monolayer per1gof sample.
and external surface of a powder or solid only after these
4.6.3 Calculation of the specific surface area (SSA), a (see
s
surfaces have been cleaned of any physically adsorbed mol-
Eq A1.7 in Annex A1), which requires knowledge of the
ecules. Such adsorbed species, for example water or volatile
monolayer capacity as well as the effective molecular cross-
organiccompounds,affectphysicaladsorptionofthegasprobe
sectional area of the adsorbate. Recommended customary
molecules used to measure surface area. Therefore, it is
values for molecules of N at 77.35 K, Ar at 87.27 K, and Kr
necessary to remove these adsorbed contaminants prior to
at 77.35 K, are provided in Table 1.
surfaceareaanalysis.Generally,suchaprocedureisperformed
byevacuatingorpurgingthesamplewithinertgas.Outgassing
5. Significance and Use
canbeacceleratedbyusingelevatedtemperatures,providedno
5.1 Advanced ceramic powders and porous ceramic bodies
irreversible sample changes occur. Typical minimum vacuum
–1
oftenhaveaveryfineparticulatemorphologyandstructurethat
levels attained are 10 Pa. Commonly used purging gases are
are marked by high surface-to-volume (S-V) ratios. These
helium, nitrogen, or a mixture of the two. The outgassing
ceramics with high S-V ratios commonly exhibit enhanced
procedure is optimal or complete, or both when: (1) duplicate
chemical reactivity and lower sintering temperatures. Results
surface area analyses produce results within expected instru-
of many intermediate and final ceramic processing steps are
ment repeatability limits, (2) constant residual vapor pressure
controlled by, or related to, the specific surface area of the
is maintained upon isolation from the vacuum source, or (3)
advanced ceramic. The functionality of ceramic adsorbents,
purging gas composition is unaffected while passing over the
separation filters and membranes, catalysts, chromatographic
sample.
carriers, coatings, and pigments often depends on the amount
6.2 The outgassing procedures and temperatures shall not
and distribution of the porosity and its resulting effect on the
produce any changes in composition, phase, or surface mor-
specific surface area.
phology of the powder specimens. The outgas temperature
5.2 This test method determines the specific surface area of
limits are determined by the stability limits of the powder
advanced ceramic powders and porous bodies. Both suppliers
samples.
and users of advanced ceramics can use knowledge of the
surface area of these ceramics for material development and
7. Apparatus
comparison, product characterization, design data, quality
7.1 Manometric (Volumetric) Apparatus—See Test Method
control, and engineering/ production specifications.
D1993 and ISO 15901-2 for description of technology.
7.2 Automated and Dynamic Flow Instruments—
Commercial instruments are available from several manufac-
turers for the measurement of specific surface area by physical
TABLE 1 Cross-Sectional Areas of Selected Commonly Used
Adsorptives adsorption. Some are automated versions of the classical
vacuum apparatus. Others may use a gravimetric technique to
Recommended Value
Adsorptive Temperature, K
of Cross-Sectional Area, nm
determine the amount of adsorbed gas on the sample surface.
A
Nitrogen 77.35 0.162
Additionally, commercial instruments are available that mea-
B
Argon 77.35 0.138
sure physical adsorption based on the dynamic flow method.
Argon 87.27 0.142
C
Krypton 77.35 0.202
7.3 Sample Cells, that when attached to the adsorption
A
Very often the orientation of the adsorbed N molecules (having quadruple
apparatus will maintain isolation from the atmosphere equiva-
moment) can be affected by specific interactions with polar groups on the surface
lent to a specified (helium) leak rate determined by the
ofadsorbent(i.e.incaseofhighlypolarsurfaces,suchaswithhydroxylatedoxide
surface groups (7-9)). This can lead to a significant reduction in the effective
manufacturer of the instrument.
cross-sectionalarea.Ifthestandardvaluefor N molecule(0.16
...