GRAIN SIZE EFFECTS ON THE THERMAL CONDUCTIVITY OF CERAMIC OXIDES. Progress Report No. 11, November 1, 1959 to April 30, 1960

Technical Report · Tue Oct 31 04:00:00 EST 1961

OSTI ID:4084500

Sintering studies were conducted on several grades of magnesia by employing hot-pressing techniques. The raw materials used had less than 1/2% impurity. In several cases 1/2% LiF was added as a sintering agent. The results are discussed in terms of grain growth as a function of temperature and time of sintering. Density variations are also shown to indicate the degree of sinstering. High-purity dense fine-grained alumina specimens were used to study the effect of grain size on thermal conductivity. The thermal conductivity at 100 to 1000 deg C decreased in specimens below 10- mu average grain size with a maximum decrease in conductivity of 8% at 2 mu . The decrease in thermal conductivity with decreasing grain size was found to follow closely an additive reciprocal volume relation. The role of impurities in masking this effect in dense alumina samples greater than 99% pure was shown by measuring the thermal conductivity of specimens with small variaticns in impurity content. (auth)

• Research Organization: New York. State Univ. Coll. of Ceramics, Alfred
• NSA Number: NSA-15-011566
• OSTI ID: 4084500
• Report Number(s): AD-240278
• Country of Publication: United States
• Language: English

Related Subjects

ADDITIVES
ALUMINUM OXIDES
CERAMICS
DENSITY
EXPANSION
GRAIN SIZE
HIGH TEMPERATURE
HOT WORKING
IMPURITIES
LITHIUM FLUORIDES
MAGNESIUM OXIDES
MEASURED VALUES
METALS, CERAMICS, AND OTHER MATERIALS
PRESSURE
SAMPLING
SINTERING
TEMPERATURE
THERMAL CONDUCTIVITY
VARIATIONS
VOLUME