The NanoTest Vantage – the Instrument of Choice for High Temperature Testing

Do your materials experience elevated temperatures?   If they are do then it is important that you gain an understanding  of their mechanical properties at operating/processing temperature. For example, testing at temperatures above 400 °C  is of great relevance to  researchers developing advanced materials for use in  aerospace, nuclear and wear-resistance applications.

In order to get consistent, accurate elevated temperature results you need a high quality instrument designed for these complex measurements. The NanoTest Vantage is the instrument of choice for this.  It combines key technical advantages with the expertise of Micro Materials This expertise has been gained through collaborating with leading scientists in this field for over ten years.. Key technical advantages provide you with superior results.

Figure 1. Peer-reviewed published papers covering measurements at 400 °C and above
This is due to (1) the NanoTest actively heating both the sample and the indenter (2) horizontal loading to avoid convection at the displacement sensor (3) patented stage design (4) patented thermal control method.

 

These four key advantages provide the highest thermal stability and lowest thermal drift. Figure 1 Illustrates how our experience and ability have resulted in high quality publications for NanoTest users. Of all peer-reviewed published papers, only data from the NanoTest has been used  in any investigations at temperatures of 400 °C or more (survey carried out October 2013)

 

 

 

Figure 2: Micro Materials patent protected high temperature solution for the NanoTest Vantage

 

This clear advantage is due to Micro Materials unique high temperature solution. Separate active heating of both the indenter and the sample to the same temperature minimises/eliminates any thermal gradient ensuring isothermal contact. The first report of dual active heating was by Micro Materials in 2000 [1]. Due to the ultra-low drift rate obtained this approach has since been used in almost all publications reporting data over 200 °C.

Practice has shown that it is not sufficient to only heat the sample before indentation, as this produces a large thermal gradient between the hot sample and cold indenter. When a non-heated indenter comes into contact with  a heated sample, heat will conduct onto the indenter from the sample causing indenter expansion. Consequently the instrument measures a combination of the indenter penetrating the sample and the dimensional change of the indenter – thus compromising the experiment.. These effects are magnified when the sample has a high thermal conductivity.

 

Figure 3: Contact temperature uncertainty when non-heated indenter is used

The problems with sample-only heating were recently highlighted by several different groups using instruments from different manufacturers [3-5]. All these studies reported elevated temperature indentation curves dominated by thermal drift when sample-only heating was used.  When sample-only heating was used in the study of the temperature dependence of the indentation size effect on copper the drift rates increased by a factor of x70 as the temperature rises, reaching 7 nm/s at 200 °C [6].

Of course, simply heating the sample and indenter and probe is not enough.  If heat flow across the contact is to be avoided the probe and indenter must be at the same temperature prior to contact being made.  This is achieved by a patented method of thermal control, heat flow to other parts of the instrument is significantly reduced by a patented stage design.  Reduced heat flow means that reliable measurements can now be made at even higher temperatures with thermal drift rates comparable to those achieved at room temperature. This has been demonstrated by groups working at temperatures up to 750 °C [2]

The conclusion is therefore that if you want to obtain meaningful, consistent results at elevated temperature measurements, the instrument to use is the NanoTest Vantage from Micro Materials.
 
References
1.              J.F. Smith and S. Zheng, Surf. Eng., 6 (2000) 143.
2.              J. Milhans et al, Journal of Power Sources, 196 (2011)  5599.
3.              N.M. Everitt et al, Philos. Mag., 91 (2011) 1221.
4.              F. Tang and L.C. Zhang, Adv. Mater. Res., 325 (2011) 684.
5.              R. Zarnetta et al, Mater. Sci. Eng. A, 528 (2011) 6552.
6.              O. Franke  et al, J. Mater. Res., 25 (2010) 1225.