DiL High Precision Dilatometer
Pushrod dilatometry is a method for characterizing dimensional changes of a material as a function of temperature. The measurement may be performed across a temperature range (e.g. from 800° to 1,600°C), or a specific controlled temperature program to mimic industrial processes, firing regimes, or a material’s operating environment. The coefficient of thermal expansion (?) is defined as the degree of expansion (?L) divided by the change in temperature (?T).
A precise understanding of thermal expansion behaviour provides crucial insight into firing processes, the influence of additives, reaction kinetics and other important aspects of how materials respond to environmental changes. Typical applications include: the determination of the coefficient of thermal expansion, annealing studies, determination of glass transition point, softening point, densification, kinetics and sintering studies.
C-Therm dilatometers offer high resolution and stability across a broad measurement range. With unparalleled ease-of-use, high adaptability, and modular design, C-Therm dilatometers offer researchers a robust cost-effective solution to their characterization needs.
Conforms to all major standard test methods for dilatometry, including ASTM E228.
Comparing Raw vs. Fired Ceramic
Comparison of a ceramic’s thermal expansion before and after firing gives insight into its behavior across a range of temperatures. This data is valuable in refining the firing process, and understanding how a material performs in high-temperature applications.
The unfired raw ceramic (white) undergoes a variety of complex irreversible changes (X) such as diffusion, water expulsion, chemical reaction and sintering, as well as reversible overall thermal expansion. In contrast, the fired ceramic (blue) exhibits only thermal expansion and a phase transition (O) at 552ºC, demonstrating the overall effects of firing and the resulting fired ceramics thermal expansion behavior.
Understanding Ceramic Glazes
Glazing is a critical process in the final production of ceramics, from capacitors to cookware. To ensure a properly glazed ceramic, the Coefficient of Thermal Expansion (CTE) must be considered for both the glaze and the base ceramic. Ideally, the glazing exhibits a slightly lower CTE than the ceramic to facilitate a tight lamination. A larger glaze CTE can result in cracking and a weaker finished product, due to a CTE mismatch between the glaze and substrate.
A ceramic glaze (white) was heated through its glass transition point (Tg) at 785ºC and to its softening point (894ºC). The resulting CTE (blue) is calculated and displayed in real-time via the right y-axis.
|Temperature Range||Room Temperature to 1600°C|
|Change of Length Resolution||1.25nm/digit|
|Atmosphere||Air, Vacuum, Inert Gas, Oxidizing, Static & Dynamic|
|Sample Dimensions||10 to 50mm long x max ? 4 - 12mm|
|Sample Holder||Fused Silica, Alumina|
|Configurations||Single or Dual LVDT System 1200ºC or 1600ºC Modular Furnace|
|Heating Element||Kanthal Wire (FeCrAl), SiC|
|Rate of Increase (ºC)||Up to 50ºC/min|