Standard Test Method for Linear Thermal Expansion of Solid Materials with a Push-Rod Dilatometer
Thermal Linear Analysis determines the expansion and/or contraction characteristic of a specimen as a function of temperature. Numerical and graphical results show the percent of linear thermal change (expansion or shrinkage) versus temperature using an Orton dilatometer. Tests on larger refractory specimens can also be made using a vertical thermal expansion furnace (see ASTM C832).
Cryogenic -175 to 300°C: N/A
25 to 1000°C: $165
25 to 1500°C: $225
25 to 1600°C: $260
Cryogenic-175 to 300°C: N/A
25 to 1000°C: $215
25 to 1500°C: $285
25 to 1600°C: $340
Cryogenic-175 to 300°C: $190
25 to 1000°C: $250
25 to 1500°C: $320
25 to 1600°C: $345
Cryogenic-175 to 300°C: N/A
25 to 1000°C: $290
25 to 1500°C: $385
25 to 1600°C: $435
Sample Required: For specimens run to 1000°C, the maximum diameter is 1/2" and the standard lengths are 1/2", or 1", or 2". For specimens greater than 1000°C, the maximum diameter is 5/8" and the standard length is 1". Length can vary by 0.1". Specimen ends need to be flat and parallel and within ± 0.001". Tests can be made on specimens of non-standard length and unusual shapes (foils, wafers, or stacking small pieces).
Heating and Cooling Rates: 3°C/minute (standard)
ASTM Standard Conditions: Thermal linear analysis can be performed according to other standard conditions, such as outlined in C372, C824, and E831.
1.1 This test method covers the determination of the linear thermal expansion of rigid solid materials using push-rod dilatometers. This method is applicable over any practical temperature range where a device can be constructed to satisfy the performance requirements set forth in this standard.
Initially, this method was developed for vitreous silica dilatometers operating over a temperature range of -180 to 900°C. The concepts and principles have been amply documented in the literature to be equally applicable for operating at higher temperatures. The precision and bias of these systems is believed to be of the same order as that for silica systems up to 900°C. However, their precision and bias have not yet been established over the relevant total range of temperature due to the lack of well-characterized reference materials and the need for interlaboratory comparisons.
1.2 For this purpose, a rigid solid is defined as a material that, at test temperature and under the stresses imposed by instrumentation, has a negligible creep or elastic strain rate, or both, thus insignificantly affecting the precision of thermal-length change measurements. This includes, as examples, metals, ceramics, refractories, glasses, rocks and minerals, graphites, plastics, cements, cured mortars, woods, and a variety of composites.
1.3 The precision of this comparative test method is higher than that of other push-rod dilatometry techniques (for example, Test Method D 696) and thermomechanical analysis (for example, Test Method E 831) but is significantly lower than that of absolute methods such as interferometry (for example, Test Method E 289). It is generally applicable to materials having absolute linear expansion coefficients exceeding 0.5 m/(mC) for a 1000°C range, and under special circumstances can be used for lower expansion materials when special precautions are used to ensure that the produced expansion of the specimen falls within the capabilities of the measuring system. In such cases, a sufficiently long specimen was found to meet the specification.
1.4 Computer- or electronic-based instrumentation, techniques, and data analysis systems may be used in conjunction with this test method, as long as it is established that such a system strictly adheres to the principles and computational schemes set forth in this method. Users of the test method are expressly advised that all such instruments or techniques may not be equivalent and may omit or deviate from the methodology described hereunder. It is the responsibility of the user to determine the necessary equivalency prior to use.
1.5 SI units are the standard.
1.6 There is no ISO method equivalent to this standard.
This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
Extracted, with permission, from ASTM E228 Standard Test Method for Linear Thermal Expansion of Solid Materials with a Push-Rod Dilatometer, copyright ASTM International, 100 Barr Harbor Drive, West Conshohocken, PA 19428. A copy of the standard may be purchased from ASTM International, phone 610-832-9555, e-mail: firstname.lastname@example.org, website: www.astm.org.
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