A method for evaluating the heat resistance of structural ceramics according to which the thermally stressed state is created by blowing a directed air flow into the tip of a notch in a heated prismatic specimen is presented. For this purpose a special complexly shaped notch is formed in order to provide free inflow of the air to its tip. The radius of curvature of the notch in alumina ceramics is 5 Μm. In blowing, the heat is removed predominantly from a local volume at the tip of the notch, thus providing a “local” thermal shock. The heat resistance of alumina ceramics obtained by sintering and reaction bonding is studied. The mechanical properties of Al2O3 tend to improve after a local thermal shock. The tendency is proved by testing a statistically reliable sample of unnotched specimens by the conventional method for determining the heat resistance. This tendency can be explained by “curing” of some of the defects (commensurable with the elements of the substructure) in densely sintered ceramics under the effect of thermal stresses. This was established due to the low scattering of the values of the mechanical properties measured in testing a sample of specimens with a special notch. It cannot be detected in tests of unnotched specimens within the same sample. A heat cycle of “850‡C-water” worsens the mechanical properties of notched and unnotched specimens due to the initiated microfracture.
Refractories and Industrial Ceramics – Springer Journals
Published: Nov 21, 2007
It’s your single place to instantly
discover and read the research
that matters to you.
Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.
All for just $49/month
Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly
Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.
All the latest content is available, no embargo periods.
“Whoa! It’s like Spotify but for academic articles.”@Phil_Robichaud