Dilatometry – Thermal Expansion Measurements

Introduction of Dilatometry

The most important method for measuring how solid materials expand/contract when heated or cooled under controlled circumstances is dilatometry. By observing variations in linear dimensions, Dilatometry offers a significant understanding of the thermal characteristics of materials, facilitating the assessment and appraisal of their efficacy in a range of uses. Aside from numerous other uses, the dilatometric method is used to assess phase transformation-induced length changes during continuous heating and cooling or isothermal holding steps. Dilatometry uses dilatometers with accurate temperature control systems and displacement sensors to quantify changes in material dimensions caused by temperature, time, or stress. The importance of dilatometry is found in numerous fields, such as polymers, metallurgy, and ceramics. MaTestLab is one the leading testing service providers in the USA and Canada. We have an extensive network of testing laboratories in the USA.

Principle and Methodology of Dilatometry

A cylindrical furnace uniformly encases a sample on all sides while it is safely fastened on a holder for dilatometry tests. The sample is then heated or cooled inside the furnace at a predetermined rate. Typically, mechanical, optical interferometry, thermomechanical, or thermo-optical techniques are used to quantify the change in linear dimensions.
In mechanical dilatometry, a push rod in contact with the sample transfers linear displacement to a displacement sensor system located outside the furnace. Using optical sensors, optical interferometry calculates the displacement of the sample ends in terms of a monochromatic source’s wavelengths. Transducers are used in thermomechanical procedures to translate mechanical displacement into electrical signals. A camera and light beam are used in thermo-optical analysis to record the shadows the sample casts.
A computer processes the test results data to determine how the sample length changed. Dilatometry systems accommodate specimens of non-standard sizes by providing a range of furnace layouts and sensor options. Furnaces can reach temperatures up to 2500°C, depending on the push rod and furnace’s composition and construction. Cryogenic conditions can be achieved for experiments by employing cold nitrogen or helium gas for cooling.

Instrumentation

Dilatometry makes use of advanced equipment such as dilatometers, which are equipped with sensitive displacement sensors, a perfect temperature control system, and a sample holder. These devices guarantee equal heating or cooling of samples, precisely imitate real-world conditions, and identify even the smallest dimensional changes in materials. Automated data acquisition is included in modern dilatometers to improve material study efficiency and precision.

Applications of Dilatometry

Dilatometry is used in many disciplines, including engineering, metallurgy, ceramics, and materials science. In electronics, automotive, and aerospace fields, it is crucial to comprehend how materials expand and contract to design and optimize components for performance. Dilatometry helps to create new materials and enhance manufacturing techniques by offering precise and trustworthy measurements of dimensional changes under heat.

Applications of Dilatometry

• The thermal expansion and contraction characteristics of metals, polymers, glasses, and ceramics are tested using dilatometry.  
• Provide data on thermal expansion and contraction for component engineering design.
• Assessment of thermal strains in engineered materials, parts, and frameworks
• Examine alloys’ phase transition.

Industrial Ceramics Testing and Dilatometry Refractories Applications

• Testing of insulation materials
• Testing using metallurgy and researching phase transitions in alloys
• Testing of polymers

Benefits of Dilatometry

• Rapid, easy, and accurate method
• It is possible to use regulated heating and cooling rates.
• Dilatometry comparison between various samples can be achieved

Constraints using Dilatometry

• In particular materials, errors can be caused by creep and elastic strain effects.
• The constraints of the equipment and instrumentation dictate heating and cooling rates that can be assessed.

Related Techniques

The techniques that are related to dilatometry are as follows

• Dynamic Mechanical Analysis 
• X-ray Diffraction
• Thermogravimetric Analysis 
• Thermal Mechanical Analysis