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{{Language_sel|LANG=ger|ARTIKEL=Instrumentierte Härtemessung mit Temperierung}}
{{PSM_Infobox}}
<span style="font-size:1.2em;font-weight:bold;">Instrumented hardness measurement with tempering</span>
__FORCETOC__

==General information==

Instrumented macro hardness testing with test specimen temperature control is an extension of [[Instrumented Hardness Testing – Method & Material Parameters|recording hardness testing]], which is normally carried out at room temperature. Since the [[Hardness|hardness]] of [[Polymer|polymer]] [[Material & Werkstoff|materials]], in analogy to other mechanical properties, is strongly influenced by the test temperature, this new development can be used to investigate the dependence of [[Hardness|hardness]] on test temperature as well as the [[Creep Plastics|creep]] and [[Relaxation Plastics|relaxation behaviour]] of [[Plastics|plastics]] and [[Composite Materials Testing|composite materials]] with different [[Indenter|indenter]] geometries. Another area of application for this prototype device is [[Indentation Fracture Mechanics|indentation fracture mechanics]], which is not applicable at room temperature due to the mostly ductile behaviour of plastics, but is of interest at low temperatures, especially from the point of view of small specimen quantities, e.g. in electronics or microsystem technology, for the [[Fracture Mechanical Testing|fracture mechanical characterisation]] of [[Toughness|toughness]].

==Measurement system with tempering==

The basic design of the measuring system with connected temperature chamber in the range from 20 °C to -100 °C is shown in '''Fig. 1''' below. For investigations in the temperature range from 20 °C to +100 °C, the chamber can be converted with a heating table system.

[[File:InstrHardMeasTemp_Fig-1.jpg|650px]]
{|
|- valign="top"
|width="50px"|'''Fig. 1''':
|width="600px" |Schematic Arrangement of Instrumented Macrohardness with Temperature Chamber
|}

Due to the adapted temperature control, an extended contact foot and [[Indenter|indenter]] must be used, in contrast to instrumented hardness measurement without temperature control. Since the measuring system works with a relative indentation depth measurement between the contact ring and [[Indenter|indenter]], no temperature compensation of the measurement result is required for this test method. The working distance is determined by a reference measurement, which must be carried out when changing specimens and temperatures.

The temperature chamber has a pair of plates for heating or cooling, with temperature regulation achieved via a modified Eurotherm controller with two thermal sensors. The thermal sensors are integrated in the centre of the lower and upper plates. The cascade regulation is designed so that the upper thermal sensor acts as the master, controlling the set temperature value. The lower temperature sensor controls the slave control loop, which means that the lower plate has a difference of approx. 10 K to the upper plate, ensuring only slight overshoot and rapid attainment of the set-point. The regulation behaviour of the system can be controlled via the connected computer.

Adapting hardness measurement to a [[Material Testing Machine|universal testing machine]] offers the advantage of being able to select different control systems and test types. This makes it possible to control the test via the load, the indentation depth or the traverse path, which also enables [[Instrumented Hardness Measurement – Relaxation|creep]] and stress relaxation tests to be performed depending on the test temperature. Furthermore, various [[Indenter|indenters]] such as Vickers, Knoop or Berkovich diamonds, or hardened steel balls and carbide balls of various diameters can be used

==Specimen positioning in the temperature chamber==

The specimen size is limited by the temperature chamber and should not exceed 50 x 50 mm² in base area and a minimum height of ten times the expected indentation depth. Furthermore, the specimens must be plane-parallel and smooth, although roughness is not as important here as it is in microhardness testing. The specimen is positioned in the temperature chamber using a micrometer screw with a positioning plate ('''Fig. 2''').

[[File:InstrHardMeasTemp_Fig-2.jpg|400px]]
{|
|- valign="top"
|width="50px"|'''Fig. 2''':
|width="600px" |Specimen positioning in the open temperature chamber
|}

[[File:Instrumentierte_Härtemessung_Temperierung_2.JPG]]
{|
|- valign="top"
|width="50px"|'''Fig. 3''':
|width="600px" |View of specimen positioning in the temperature chamber
|}

==See also==

* [[Instrumented Hardness Testing – Method & Material Parameters|Instrumented hardness test – method & material parameters]]
* [[Instrumented Hardness Measurement – Creep|Instrumented hardness test – creep]]
* [[Instrumented Hardness Measurement – Relaxation|Instrumented hardness measurement – relaxation]]
* [[Instrumented Hardness Measurement – Indentation Depth Measurement with Modified Contact Foot|Instrumented hardness measurement, Indentation depth measurement with modified contact foot]]
* [[Hardness]]

==References==

* [[Bierögel, Christian|Bierögel, C.]], Schöne, J., [https://researchgate.net/profile/Ralf-Lach Lach, R.], [[Grellmann,_Wolfgang|Grellmann, W.]]: Bewertung des temperatur- und zeitabhängigen Verhaltens von Thermoplasten und Elastomeren mittels der instrumentierten Makroeindringprüfung. In: [https://www.researchgate.net/profile/Wolfgang-Grellmann Grellmann, W.] (Ed.): Neue Entwicklungen in der Werkstoffprüfung – Herausforderung an die Kennwertermittlung. "Werkstoffprüfung 2011", December 1 and 2, 2011, Berlin, Proceedings pp. 285–292 (ISSN 1861–8154; ISBN 978-3-9814516-1-0; see [[AMK-Library]] under A 13)
* Lach, R., Schöne, J., Bierögel, C., [https://de.wikipedia.org/wiki/Wolfgang_Grellmann Grellmann, W.]: Instrumented Macroindentation Techniques for Polymers and Composites – Mechanical Properties, Fracture Toughness and Time-Dependent Behaviour as a Function of the Temperature. Macromolecular Symposia 315 (2012) 125–131; [https://doi.org/10.1016/j.polymertesting.2013.09.016 https://doi.org/10.1016/j.polymertesting.2013.09.016]
* Schöne, J.: Mehrparametrige Bewertung des temperaturabhängigen Eindruckverhaltens an Kunststofen mittels eines messtechnisch erweiterten, restrierenden Makrohärteprüfsystems. [https://www.uni-halle.de/ Martin-Luther-Universität Halle-Wittenberg], Promotion 2019, Shaker Publishing 2020 (ISBN 978-3-8440-7183-2, see [[AMK-Library]] under B 1-30)

[[Category:Hardness]]

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