Measurement Method Abbreviations:

AMDCB

- Applied Moment Double Cantilever Beam

CF

- Controlled Flaw

CNB

- Chevron Notch Beam

DCB

- Double Cantilever Beam

DT

- Double Torsion

HI

- Hertzian Indentation

ICS

- Indentation Crack Size

IS

- Indentation Strength

NDC

- Notched Diametral Compression

SCF

- Surface Crack in Flexure

SENB

- Single-Edge Notched-Beam

SEPB

- Single-Edge Precracked Beam

SR

- Short Rod

TDCB

- Tapered Double Cantilever Beam

WOF

- Work of Fracture

Property Abbreviations:

E

- elastic modulus (Young's modulus)

H

- hardness (Vickers hardness unless noted otherwise)

nu

- Poisson's ratio

Units:

SI units, unit symbols, and unit prefixes are used in the NIST Property Data Summaries.

Uncertainties:

No attempt has been made to assign uncertainties to the individual values obtained from the literature. A survey of data in the NIST Structural Ceramics Database indicates that relative combined standard uncertainties in the range of 5 % to 15 % are not unusual for fracture toughness measurements. Exceptional cases having reported uncertainties as low as 1 % or as high as 30 % can be found, but such cases are very unusual. For a comprehensive discussion on estimates of uncertainty, see "Guidelies for Evaluating and Expressing the Uncertainty of NIST Measurement Results," by B. N. Taylor and C. E. Kuyatt, NIST Technical Note 1297.

A substantial effort has been made to select data for this database on the basis of sound scientific judgment. However, the National Institute of Standards and Technology (NIST) makes no warranties regarding its use, and NIST shall not be liable for any damage that may result from errors or omissions in the database.

Certain trade names and other commercial designations are used in this work for the purpose of clarity. In no case does such identification imply endorsement by the National Institute of Standards and Technology, nor does it imply that products or services so identified are necessarily the best available for the purpose.

How are data evaluated?

Scientific and technical data may be examined from three viewpoints:

• how well is the data generation described,
• how do the data follow the known physical laws,
• and how do the data compare to other measurements or calculations of the same phenomena.

The description of data generation is crucial. The identification and control of all relevant independent variables must be addressed and demonstrated. For mature areas such as thermodynamics and atomic physics, many measurement techniques are well characterized. In these cases, the adherence to physical laws and intercomparisons predominate. For areas in which behavior is not well understood, such as corrosion, data from different experiments are not usually comparable. Consequently, documentation of control of the experimental condition is most important.

Technical inquiries:
Ceramics Division
NIST, 100 Bureau Drive, Stop 8520, Gaithersburg, MD 20899-8520
Phone: (301) 975-6119
Fax: (301) 975-5334

Property Data Summaries

Property Data Summaries are collections of property values derived from surveys of published data. These collections typically focus on either one material or one particular property. Studies of specific materials typically include thermal, mechanical, structural, and chemical properties, while studies of particular properties survey one property across many materials. The property values may be typical, evaluated, or validated. Values described as typical are derived from values for nominally similar materials.

CAUTION! Typical values are only representative of trends of values commonlyfound for a general class of materials and are not necessarily the best or most appropriate valuesfor any particular material.

Data Evaluation Levels

The data evaluation levels used throughout the NIST Ceramics WebBook are:

• Certified (standard reference values)
• Validated (confirmed via correlations and models)
• Evaluated (basic acceptance criteria satisfied)
• Commercial (manufacturer's data)
• Typical (derived from surveys)
• Research (preliminary values; work in progress)
• Unevaluated (all other data)

Use of Commercial Names

Certain commercial equipment, instruments, or materials are identified in this document to specify adequately the experimental procedures and conditions. Such identification does not imply recommendation or endorsement by the National Institute of Standards and Technology, nor does it imply that the materials or equipment identified are necessarily the best available for the purpose.