1. Organization of hydrogen energy technologies training

2. I was attending training program on samples preparation at University of Poitiers, Metallurgic Physics Laboratory. 2007.03.10 – 03.30

3. Content of the report Surface preparation; Surface roughness measurements; Vickers hardness test.

4. Surface preparation The objective is to produce the surface for analysis. The following procedures are recommended for preparation of samples suitable for microscopy examination: Physical grinding; Polishing.

5. Physical grinding Grinding/polishing machine for 200 mm disc and 2 speeds, 150/300 rpm RotoPol - 22 Silicon carbide paper

6. Experimental results ab cd Sample (Ni based superalloy) surface grinding parameters: a)P800 5 min 5 N; b)P1200 5 min 5 N; c)P2400 15 min 5 N; d)P4000 20 min 5 N.

7. Polishing Aerosol spray made with polycrystalline diamond mixed with a liquid carrier. The carrier quickly evaporates after application, leaving a uniform layer of diamond particles on the cloth. Non-woven textile buffed to eliminate high peaks, creating a flat polishing surface Alumina Powder is specially treated to reduce the number of agglomerates

8. Experimental results a dc b e Sample surface after polishing with a) 6 μm, 15 min b) 3 μm, 15 min c) 1 μm, 20 min d) ¼ μm, 20 min e) Al suspension (0.1 μm, 30 min)

9. Surface roughness measurements Talysurf CCI System 3D surface profiling with high accuracy Coherence Correlation Interferometer is non-contact and non-destructive suitable for profile peaks between 1nm and 100um in height 0.01nm resolution high speed data aquitision and analysis

10. How It Works Optical schematic of interference microscope used to measurement for surface structure Mirau interferometer

11. Experimental results Sample surface after polishing with Al suspension Sq = 0.05028 μm Sa = 0.03854 μm

12. Experimental results Sample surface after grinding with P4000 abrasive paper

13. Vickers Hardness Test experimental technique The CSM Indentation Testers General principle of the nano indentation apparatus

14. Vickers Hardness Test

15. Nanoindentation testing Surface profile after unload Typical nanoindentation curve for an elastoplastic material

16. Experimental results Micro hardness measurement graph of nonnitrided sample (500 mN) Micro hardness measurement graph of nitrided sample (500 mN)

17. Experimental results Penetration depth nitrided (μm) Penetration depth nonnitrided (μm) Normal force Operation length 0.680.75015 s 0.99100 0.981.4200 1.682.3500 2.911000 Penetration depth (μm) Normal force (μm) Operation length 0.755015 s 1.88200 3.57400 6.04800

18. Conclusion After surface treatment with physical grinding and polishing we got quit flat surface which is proper for microscope examination. Microscope interferometer is effective and nondestructive method for determination of the surface profile Nano hardness tester let us know the mechanical properties of very small and localised regions of material surface. Nano hardness tester let us know mechanical properties of coatings and thin films without influence of substrate. From nano hardness measurements results we can make a conclusion that nitriding is effective way to improve mechanical properties of metals.