Physical Properties of Ceramics
Reprinted with permission of the Coors Ceramics Company The development of new ceramic materials is helping to meet the growing demand in industrial and laboratory applications. Coors ceramic components are harder, lighter, and more resistant to heat, corrosion, and wear than steel counterparts. Coors ceramic demonstrates excellent dimensional stability and can be manufactured to meet precise tolerances. Its strength and temperature resistance, combined with high resistivity and dielectric strength, make it an attractive alternative.
Chemical-Porcelain has excellent thermal-shock resistance. The chemical-porcelain used to make the products featured has a fusion point of 1670°C and a softening point of 1400°C.
High-Alumina Ceramicware made of 99.8%-pure aluminum oxide, is frequently selected by metallurgists and chemists. It is useful for applications requiring high-temperature analysis with contaminant-free results. This highly refractory labware is meant for use in reducing and oxidizing atmospheres. It can be used with refractory metals such as molybdenum, platinum, rhodium, tungsten, tantalum and iridium. It is inert in hydrogen and carbonaceous atmospheres and offers high resistance to alkalies and other fluxes at low temperatures.
High-alumina chemical tests conducted by Coors Ceramics Company using crucibles weighing approximately 32g yielded the following results:
Chemical test | Temp | Time | Wt loss |
Hot conc. H2SO4 | 100°C | 4 hrs | ~6 x 10-4% |
Hot 10% NaOH | 100°C | 4 hrs | ~9 x 10-4% |
Hot 50% H3PO4 | 90°C | 4 hrs | ~0.16% |
Typical Ceramic Characteristics Summary
This Table Scrolls Left to Right
Physical Properties* | Chemical-porcelain | High-alumina |
Maximum use temp (no load) | 1400°C (2560°F ) unglazed 1150°C (2100°F) glazed | 1750°C (3182°F) |
Thermal-expansion coefficient | 3.56 x 10-6 from 20 to 200°C gradually increasing to 4.69 x 10-6 at 1000°C | 8.0 x 10-6/°C from 25 to1000°C |
Thermal shock resistance | Good | Fair |
Compressive strength | - | >300,000 psi |
Density (g/cc) | 2.5 (typical) | 3.9 (typical) |
Hardness | Rockwell 45N | 57.5 | 79 |
Mohs | - | 9 |
Gas permeability | 0 | 0 |
Water absorption | 0 | 0 |
Maximum heating/cooling rate | 200°C (392°F)/hour | 150°C (302°F)/hour |
Autoclavable | Up to 137°C (280°F) at 30 psi | Up to 137°C (280°F) at 30 psi |
Corrosion resistance | Acid | Good except HF | High except HF |
Alkali | Good | High |
Metals | Fair to good | High except Na, Li |
Atmospheric | - | OK oxidizing, reducing |
Advantages | Wide variety of applications, economical | High-purity 99.8% alumina, intended for use in oxidizing and reducing atmospheres. Highly refractory. Very corrosion resistant. |