ASTM C467-14(2023)

Standard Classification of Mullite Refractories

SIGNIFICANCE AND USE
3.1 The mullite content of an alumina-silica refractory material has an important influence on volume stability, load-bearing properties, and its satisfactory use in refractory applications. This classification is considered useful for purchase specifications and quality control.
SCOPE
1.1 This classification covers refractory products consisting predominantly of mullite (3Al2O3·2SiO2) crystals that are formed by either converting any of the sillimanite group of minerals, or synthesizing from appropriate materials in a melt or sinter process.  
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.  
1.3 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-2023
• ICS: 81.080 - Refractories
• Technical Committee: C08 - Refractories
• Drafting Committee: C08.92 - The Joseph E. Kopanda Subcommittee for Editorial, Terminology and Classification

Relations

• Refers: ASTM C16-03(2018) - Standard Test Method for Load Testing Refractory Shapes at High Temperatures
• Effective Date: 01-Feb-2018
• Refers: ASTM C16-03(2012)e2 - Standard Test Method for Load Testing Refractory Shapes at High Temperatures
• Effective Date: 01-Oct-2012
• Refers: ASTM C16-03(2012)e1 - Standard Test Method for Load Testing Refractory Shapes at High Temperatures
• Effective Date: 01-Oct-2012
• Refers: ASTM C16-03(2012) - Standard Test Method for Load Testing Refractory Shapes at High Temperatures
• Effective Date: 01-Oct-2012
• Refers: ASTM C832-00(2010) - Standard Test Method of Measuring Thermal Expansion and Creep of Refractories Under Load
• Effective Date: 01-Nov-2010
• Refers: ASTM C16-03(2008)e1 - Standard Test Method for Load Testing Refractory Shapes at High Temperatures
• Effective Date: 01-Aug-2008
• Refers: ASTM C16-03(2008) - Standard Test Method for Load Testing Refractory Shapes at High Temperatures
• Effective Date: 01-Aug-2008
• Refers: ASTM C832-00(2005) - Standard Test Method of Measuring Thermal Expansion and Creep of Refractories Under Load
• Effective Date: 01-Dec-2005
• Refers: ASTM C16-03 - Standard Test Method for Load Testing Refractory Shapes at High Temperatures
• Effective Date: 01-Nov-2003
• Refers: ASTM C16-03e1 - Standard Test Method for Load Testing Refractory Shapes at High Temperatures
• Effective Date: 01-Nov-2003
• Refers: ASTM C16-02 - Standard Test Method for Load Testing Refractory Shapes at High Temperatures
• Effective Date: 10-Nov-2002
• Refers: ASTM C832-00 - Standard Test Method of Measuring the Thermal Expansion and Creep of Refractories Under Load
• Effective Date: 10-Oct-2000
• Refers: ASTM C16-81(2001) - Standard Test Method for Load Testing Refractory Brick at High Temperatures
• Effective Date: 28-Dec-1981

Overview

ASTM C467-14(2023), Standard Classification of Mullite Refractories, provides a comprehensive classification system for refractory products composed predominantly of mullite (3Al₂O₃·2SiO₂) crystals. Developed by ASTM International, this standard is essential for ensuring the quality, reliability, and performance of alumina-silica refractory materials. The classification is particularly valuable for purchase specifications and quality control processes, enabling consistency in properties such as volume stability and load-bearing capacity. The standard is recognized internationally and aligns with principles from the World Trade Organization Technical Barriers to Trade (TBT) Committee.

Key Topics

• Mullite Content and Influence
  The proportion of mullite in alumina-silica refractories significantly affects key characteristics, including:

  • Volume stability during thermal cycling
  • Load-bearing properties at high temperatures
  • Overall suitability for demanding refractory applications

• Scope of Products
  The standard covers refractory products where mullite is the predominant crystal phase, created either by:

  • The transformation of minerals from the sillimanite group
  • Synthesis from other suitable materials through melting or sintering processes

• Classification Criteria

  • Alumina content: Ranges between 56% to 79%
  • Impurities (maximum): 5% (impurities refer to metal oxides other than those of aluminum and silicon)
  • Maximum deformation: 5%

• Testing Requirements

  • Compliance is determined with test specimens of standard dimensions, using specific ASTM test methods:
    • Alumina content by X-ray fluorescence (XRF) and inductively coupled plasma (ICP)
    • Load testing in accordance with ASTM C16
    • Thermal expansion and creep testing per ASTM C832
  • Retesting is permitted to ensure reliability if initial results are inconsistent

Applications

Mullite refractories classified under ASTM C467 are integral to high-temperature industrial processes, thanks to their excellent thermal stability and mechanical strength. Typical applications include:

• Metallurgical Furnaces
  Used in lining furnaces, kilns, and incinerators where resistance to chemical attack, thermal cycling, and mechanical stress is critical.

• Petrochemical and Power Generation
  Utilized in reactors and boilers to handle severe thermal and chemical environments.

• Purchase and Quality Control
  Provides a standardized basis for specifying and verifying the quality of mullite refractory bricks and shapes, supporting procurement, manufacturing, and inspection procedures.

Related Standards

Organizations utilizing ASTM C467-14(2023) may also reference the following associated standards to further define testing and quality requirements for refractory products:

• ASTM C16 – Test Method for Load Testing Refractory Shapes at High Temperatures
• ASTM C832 – Test Method for Measuring Thermal Expansion and Creep of Refractories Under Load

These related standards detail the methods used to determine mechanical and thermal properties critical to the performance of mullite refractories.

---

Keywords: ASTM C467, mullite refractories, alumina-silica refractory, classification, standard, high temperature, volume stability, load-bearing, quality control, industrial furnaces, refractory products, ASTM standards

For detailed requirements and testing methodology, refer to the official ASTM documentation for C467-14(2023) and the associated referenced standards.

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: C467 − 14 (Reapproved 2023)
Standard Classification of
Mullite Refractories
This standard is issued under the fixed designation C467; 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 bearing properties, and its satisfactory use in refractory appli-
cations. This classification is considered useful for purchase
1.1 This classification covers refractory products consisting
specifications and quality control.
predominantly of mullite (3Al O ·2SiO ) crystals that are
2 3 2
formed by either converting any of the sillimanite group of
4. Basis of Classification
minerals, or synthesizing from appropriate materials in a melt
4.1 The refractory products falling within the scope of this
or sinter process.
classification are classified by chemical and physical tests to
1.2 The values stated in inch-pound units are to be regarded
meet the following requirements:
as standard. The values given in parentheses are mathematical
Alumina content, % 56 to 79
conversions to SI units that are provided for information only
A
Impurities, max, % 5
B
and are not considered standard.
Deformation, max, % 5
1.3 This international standard was developed in accor-
A
Impurities refer to metal oxides other than those of aluminum and silicon.
dance with internationally recognized principles on standard-
B
When tested in accordance with 6.1.2.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom- 5. Test Specimens
mendations issued by the World Trade Organization Technical
5.1 Testing for compliance with this classification shall be
Barriers to Trade (TBT) Committee.
1 1
performed on 9 by 4 ⁄2 by 2 ⁄2-in. (228 by 114 by 64-mm)
rectangular brick as made, or on specimens of this size cut
2. Referenced Documents
from larger shapes, utilizing existing plane surfaces as much as
2.1 ASTM Standards:
possible.
C16 Test Method for Load Testing Refractory Shapes at
High Temperatures
6. Test Methods
C832 Test Method for Measuring Thermal Expansion and
6.1 The properties enumerated in this classification shall be
Creep of Refractories Under Load
determined in accordance with the following ASTM methods:
NOTE 1—Chemical analysis of refractory products is determined by a
6.1.1 Alumina Content—XRF and ICP.
combination of X-ray fluorscence (XRF) and inductively coupled plasma
6.1.2 Load Test—Schedule 6 of Table 1 in Test Method C16.
(ICP) using standard reference materials (SRM), including various types
6.1.3 Thermal Expansion and Creep—Test Method C832.
of minerals and refractory materials which are available from the National
Institute of Standards and Technology a
...