NIST materials properties databases for advanced ceramics

Abstract

The NIST Ceramics Division maintains two databases on the physical, mechanical, thermal, and other properties of high temperature superconductors and structural ceramics. Crystallographic data are featured prominently among the physical property data and serve several important functions in the classification and evaluation of the property values. The scope of materials, properties, and data evaluation protocols are discussed for the two databases.

Strength of additively manufactured alumina with different debinding and sintering heat treatments

“…22 To compare on equal terms, we convert their reported density data to relative density using the NIST standard reference materials data to find a relative density of 98.6%. 50 The relative density reported in this work is 0.7% higher than the relative density achieved by Schwentenwein and Homa.…”

“…49 Relative densities were calculated using the NIST standard reference material for high-purity alumina (3.984 g/cm 3 ). 50 For heat treatment development experiments, the density of one specimen from each heat treatment condition was measured after flexural strength testing. For large batches of specimens created for Weibull parameter characterization, the densities of 12 specimens per condition were measured after flexural strength testing.…”

Microstress in the matrix of a melt‐infiltrated SiC/SiC ceramic matrix composite

“…As reported elsewhere, we can estimate the thermoelastic stresses for the silicon and SiC from cooling from the freezing point of the silicon to room temperature. Using literature values for the temperature‐dependent thermal expansion of SiC and of silicon, and approximating the bulk moduli with the room temperature bulk modulus values of 100 GPa for silicon and 200 GPa for SiC, we expect a compressive microstress of 103 MPa in silicon and a tensile microstress of 26 MPa in SiC with a 20% volume of silicon. These are of the correct sense, but are much lower than what we infer from Raman spectroscopy.…”

Linking flexural strength and strength‐limiting flaws in additively manufactured alumina with print parameter variations

“…Density was determined using the Archimedes method, as per ASTM C20, 19 and relative densities were calculated using a reference value of 3.984 g/cm 3 from the NIST standard reference material for high-purity alumina. 20 The densities of 12 specimens were measured for each of the 7 batches of flexure bars. For fractography, every fracture surface from every flexure bar was observed using a stereomicroscope (Zeiss Discovery.V8 SteREO; Oberkochen, Germany) to examine surface features and identify defect origins.…”