High temperature nanoindentation up to 810 C: Experimental Optimization

Transcription

1 High temperature nanoindentation up to 810 C: Experimental Optimization N. X. Randall, M. Conte, B. Bellaton, Jarod Zhao Anton Paar TriTec SA, Rue de la Gare 4, Peseux CH2034, Switzerland G. Mohanty, J. Schwiedrzik, J. M. Wheeler, J. Michler EMPA, Swiss Federal Laboratories for Materials Science and Technology, Laboratory for Mechanics of Materials and Nanostructures, Feuerwerkerstrasse 39, Thun CH3602, Switzerland

2 Summary 1 Background to High Temperature Indentation Testing 2 Current Challenges 3 How does UNHT 3 HTV address such challenges? 4 Basic system overview 5 Validation of specifications over entire temp. range 6 Application examples 7 Conclusions

3 Background to high temperature testing Industrial applications are: Cutting tools hard coatings for high speed machining; Semiconductors; Thermal barrier coatings; Nuclear materials Academic applications are: Investigation on dislocation induced by high temperature and deformation; Creep and fatigue changes with temperature; Hardness variation with temperature; Etc.

4 Current challenges to high temperature indentation Sample and tip oxidation Tip Hardness decay Sample and tip interaction Tip contamination Diamond tip after contact with steel sample at 500 C J. M. Wheeler and J. Michler, Review of Scientific Instruments 84, (2013) J. M. Wheeler and J. Michler, Review of Scientific Instruments 84, (2013) Courtesy of UTC, France High Vacuum or Inert gas environment Tip material opportune choice depending on the sample material Tip cleaning process

5 UNHT 3 HTV High Vacuum System Features P2 P1 Vacuum Buffer Ultimate Vacuum: 10-7 mbar Process Vacuum: 10-6 mbar Vacuum chamber Volume: 100 liters Pumping speed: 800 l/s Primary pump is rotary vane Secondary pump is turbo molecular with magnetic levitation bearings Partial pressure mixture gas control: mbar Flow gas mixture control rate: sccm User available additional ports Integrated compressed air-pistons

6 UNHT 3 HTV High Vacuum System Features High Vacuum enclosure Ultimate vacuum 2x10-7 mbar Active air pads Integrated electronics Water cooling circuit Damped frame

7 Some pictures

8 UNHT 3 HTV Adjustable sample holder Cement vs clamping Patent pending PCT/EP2017/051035

9 UNHT 3 HTV Head Design A1 A2 A1 & A2: piezoelectric actuators FN Feedback loop on force sensor I sample R Feedback loop for accurate low force sensing Reference contact Load-depth curve Dz Stage Motorized Z table

10 UNHT 3 HTV Head Features Vacuum Compatible Piezos Infra Red Heaters (x2) Cu-Be Springs, range mn Zerodur frame ensures negligible thermal expansion (0 100 C) Water Cooled Jacket Reflective Mirror Long Shaft Indenter & Reference Pending Patent EP : UNHT3 HT Tip heating design Pending Patent EP : UNHT3 HT Design of heated probe

11 UNHT 3 HTV Heating System Features: IR Bath A comprehensive approach is needed: the problem is not only the heating up but also controlling the temperature and keeping it stable for a long time. The whole system must be considered. Tip heating system Indentation/reference tips Sample heating module Pending Patent EP : UNHT 3 HT Sample holder arrangement Sample

12 UNHT 3 HTV Temperature Management UNHT 3 HT Head Thermocouple [Security for head < 40 C] Indenter Thermocouple Reference Thermocouple Sample Thermocouple * Sample Holder Thermocouple [Security] Sample Heater Power Indenter, Reference and Sample temperatures can be regulated independently in 3 ways: (1) Power regulation (e.g., constant wattage control, user definable) (2) Target temperature (via PID control, user definable) (3) Slope or heating ratio ( /min, user definable) * Two thermocouples are available: (1) Under sample holder (2) On sample surface User can choose which of the 2 thermocouples to use for regulation

13 UNHT 3 HTV Temperature Management Z 0

14 High Purity Molybdenum (Raw Data) Thermal drift measurements (raw data) on pure Molybdenum at 810 C showing < 2 nm/min. average drift rate over a 300 s pause at 10% of maximum applied load.

15 High Purity Molybdenum (Raw Data) 23 C 23 C 810 C 810 C

16 Titanium Nitride (TiN) on WC substrate TiN thickness: 3 µm Maximum load: 30 mn, holding time 10 sec

17 Titanium Nitride (TiN) on WC substrate (Raw Data) TiN thickness: 3 µm Maximum load: 30 mn, holding time 10 sec RT 200C 400C 600C Hardness (GPa): Elastic Modulus (GPa):

18 Alumina (Al 2 O 3 ) on WC substrate Al 2 O 3 thickness: 10 µm Maximum depth: 400 nm, holding time 10 sec Loading/Unloading speed: 150 nm/min

19 THANK YOU