High-Temperature Thermomechanical Analyzer

What is the High-Temperature Thermomechanical Analyzer?

A high-temperature thermomechanical analyzer reaches 1500 to 1700 degrees Celsius with an alumina or graphite furnace, measuring expansion, sintering shrinkage and softening of ceramics, refractories, glasses and metal oxides used in demanding processes.

Overview

Alumina probes and holders allow operation to about 1600 degrees Celsius in air, while graphite probes and furnaces extend the range and are used under inert gas or vacuum. Sintering studies are the most common application: as the compact densifies, the probe records shrinkage, and the onset and rate of shrinkage identify the sintering window and the effect of additives. Softening under a defined load gives the refractoriness-under-load behaviour of firebricks, and expansion curves show quartz inversions and phase changes in oxides. Typical specifications are a temperature range from ambient to 1700 degrees Celsius, displacement resolution of 10 to 50 nanometres, heating rates from 1 to 20 degrees Celsius per minute and controlled cooling. Long hold times at temperature are often required, so drift of the displacement channel and stability of the probe become important performance criteria.

How does it work?

A probe rests on the specimen and is connected to a linear variable differential transformer, which converts displacement into an electrical signal with resolution near one nanometre. A furnace programs the temperature while a defined static or oscillating load holds the probe in contact. Depending on the probe and holder fitted, the instrument measures expansion, compression, penetration, tension or three-point bending, and the same displacement channel serves all modes. Coefficient of thermal expansion is calculated from the slope of the expansion curve over a chosen temperature interval, and softening or glass transition temperatures are read from the onset of probe penetration. Calibration uses reference materials of known expansion such as fused silica or aluminium, plus melting point standards for the temperature channel. Probe material, load and contact geometry must be recorded because they influence the measured displacement, and sample preparation must give parallel, flat faces.

What are the key features?

• Furnace operation to 1700 °C with alumina or graphite components
• Sintering shrinkage measurement with onset and rate evaluation
• Refractoriness-under-load testing with defined contact stress
• Displacement drift below 10 nm per hour at temperature
• Inert gas or vacuum atmosphere for graphite configurations
• Long hold and controlled cooling programs

What are the technical specifications?

A typical high-temperature thermomechanical analyzer configuration offers temperature range of Ambient–1700 °C, displacement resolution of 10–50 nm, heating rate of 1–20 °C/min, contact load of 0.01–2 N, or defined stress for refractories, drift at temperature of < 10 nm/h and probe materials of Alumina, graphite, sapphire. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The High-Temperature Thermomechanical Analyzer is used in ceramic sintering and densification, refractoriness under load of firebricks, glass and glaze expansion behaviour, metal oxide phase transitions and solid oxide fuel cell component testing. Across the wider TMA class, laboratories also deploy it for coefficient of thermal expansion of metals and ceramics, polymer softening and glass transition and electronic substrate and packaging materials.

Which standards and certifications apply?

Relevant standards and methods include ASTM E831, ASTM E1363, ASTM D696, ISO 11359-1, ISO 11359-2 and IEC 61010-1. Certification candidates for this model are CE, IEC 61010-1 safety and ISO 9001 manufacturing; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Prepare specimens with parallel, flat and smooth faces, and record the original length precisely, because expansion results are normalized to it. Keep the load low enough to avoid deforming the sample, and allow the probe to settle at the starting temperature before beginning the ramp. Verify the expansion channel with a certified reference such as fused silica or aluminium and check the temperature channel with melting point standards. Beware of systematic artefacts: probe and holder expansion must be subtracted, and soft samples can show apparent shrinkage from creep under load. Keep the furnace and probe clean, replace worn probes, and use the correct purge gas to avoid oxidation or reaction with the specimen. Record mode, load, probe material, gas and calibration data with every curve.

How do I select the right High-Temperature Thermomechanical Analyzer?

Specify the high-temperature configuration when sintering, softening or expansion must be followed above about 1000 degrees Celsius, as with ceramics and refractories. If lower temperatures suffice, a standard instrument with a quartz probe gives better resolution. In an RFQ, state maximum temperature, atmosphere, probe material and expected hold times.

How does it compare with other TMA variants?

Decide the measurement mode first, because it dictates the probe and holder: expansion requires a flat-ended probe and often a horizontal or vertical dilatometer configuration, penetration and compression suit polymers and soft materials, tension suits films and fibres, and three-point bending suits rigid bars. Then set the temperature range, since it determines whether the furnace uses quartz, alumina or graphite and whether cooling uses liquid nitrogen or mechanical refrigeration. Displacement resolution matters most for thin films and low-expansion ceramics, where nanometre sensitivity is needed. Load range and control quality decide whether soft, low-modulus samples can be measured without deformation caused by the probe itself. Check the atmosphere and vacuum options, calibration standards supplied, sample preparation tooling and whether the instrument can be upgraded with a humidity generator or an automatic sample changer.