Successfully reported this slideshow.
We use your LinkedIn profile and activity data to personalize ads and to show you more relevant ads. You can change your ad preferences anytime.

ALD France nitriding process and furnaces

3,922 views

Published on

What is gas and plasma nitriding ?

Why ASPN - Active Screen Plasma Nitriding is the best nitriding technoloy ?

Published in: Engineering
  • Be the first to comment

ALD France nitriding process and furnaces

  1. 1. ALD France Gas, and plasma nitriding Process and furnace
  2. 2. 2 I.Reasons for nitriding II.Gas nitriding 1. How does gas nitriding work? 2. Structure of nitrided material 3. What kind of material can be nitrided? 4. How the gas process is controlled? 5. ALD’s solutions : NiH furnace for Gas nitriding III.Plasma nitriding 1. Plasma physics 2. How the plasma process is controlled? 3. Plasma nitriding technology improvement 4. ALD’s furnace solutions: Plasma nitriding conception IV.How to choose between the two technologies Outline
  3. 3. 1) To obtain high surface hardness (up to 1400 Hv) 1) To increase wear resistance 2) To improve fatigue life 3) To improve corrosion resistance 4) To obtain a surface that is resistant to the softening effect of heat at temperatures up to the nitriding temperature (500 °C) I. 5 reasons to nitride parts 3
  4. 4. I.Reasons for nitriding II.Gas nitriding 1. How does gas nitriding work? 2. Structure of nitrided material 3. What kind of material can be nitrided? 4. How the gas process is controlled? 5. ALD’s solutions : NiH furnace for Gas nitriding III.Plasma nitriding 1. Plasma physics 2. How the plasma process is controlled? 3. Plasma nitriding technology improvement 4. ALD’s furnace solutions: Plasma nitriding conception IV.How to choose between the two technologies Outline 4
  5. 5. Raising temperature by 40°C requires about twice more ammonia flow. II. 1. How does gas nitriding work? 2NH3 → 3H2 + 2N (dissolved in α-Fe → 3H2 + N2 (gas) 5
  6. 6. II. 2. Structure of nitrided material Oxide layer : 1-2 µm • Corrosion resistant White layer : 5-30 µm • High hardness • Abrasive resistant Diffusion zone : 10- 1000 µm • High compressive stress • High fatigue strength • Hardness higher than substrate α (0-6% N) Diffused Case Core  (6-11% N) ’ (5,6- 6% N) Fe3O4 X100 X400 ε 6
  7. 7. II. 3.What kind of material can be nitrided? Effect of alloying element additions on hardness after nitriding. Base composition is 0,25% C, 0,30% Si, 0,70% Mn Useful alloying elements for nitriding: Cr, Va, Mo, Al, Ti,… Me + nN => MeNn Me: Metal N: nitrogen The Effects of Alloying Elements on Steels Mehran Maalekian October 2007 Hardness Hv 7
  8. 8. Tables: ASM Handbook Volume 4A 2013 Nitriding II. 3. Hardness improvement Material Hardness prior to Nitriding Hardness obtained by Nitriding Iron ≈120 HV ≈250 HV Low alloyed carbon steels - i.e. AlSi 1045 ≈180 HV ≈350 HV Medium-carbon, chromium- containing low alloy steels - 1.1% Cr (AlSi 4140) - 2.5% Cr (AlSi 4340) ≈240 HV ≈240HV ≈600 HV ≈750 HV Nitriding steels - (Cr and Al) ≈240 HV ≈1000 HV Tool steels - (12% Cr) ≈600 HV >1000 HV 8
  9. 9. II. 4. How do we control the process? By controlling the nitriding potential KN Lehrer Diagram for Nitriding KN = 1 − H 0,75 H1,5 KN = pNH3 (pH2)3 Norm: AMS 2759/10 requirements for nitriding using a process controlled by the nitriding potential H2 sensor 9
  10. 10. S.S. Hosmani, R.E. Schacherl, and E.J. Mittemeijer, Kinetics of Nitriding Fe- 2 wt% V Alloy: Mobile and Immobile Excess Nitrogen, Metall. Mater. Trans. A , Vol 38, 2007, p 7– 520 °C 10h 580 °C 10h 550 °C 10h 600 °C 7h Nitrogencontent (at.%) Nitrogencontent (at.%) Nitrogencontent (at.%) Nitrogencontent (at.%) Depth (µm) Depth (µm) Depth (µm) Depth (µm) Norm: AMS 2750 pyrometric requirements for thermal processing equipmentFurnace class Temperature uniformity range (°C) 1 ± 3 2 ± 6 3 ±8 4 ±10 II. 4. How do we control the process? By controlling the temperature 10
  11. 11. The thickness of the diffusion layer is proportional to the square root of time, It follows the Fick Law Nitriding time, hours Effectivecase depth,µm Hand Book On Mechanical Maintenance Compiled by: K P Shah 𝐽 𝐷 = −𝐷 𝜕𝑐 𝜕𝑧 II. 4. How do we control the process? By controlling the time 11
  12. 12. Parameters influencing nitrided layer formation (acc. to Spies and Bergner) Compound layer thickness Case (surface) hardness Effective case depth Case hardness depth Nitriding conditions : - Higher temperature - Longer soak time - Higher KN Material composition : - Higher Cr concentration - Higher Al concentration - Higher C concentration Material structure : - Normalized - Hardened, = = = = = = = = = = = = = = = = II. 4. How do we control the process? General rules 12
  13. 13. Typical nitriding cycle 13
  14. 14. Main constituents of nitriding / nitrocarburizing installation : Vacuum Purging Furnace Control Cabinet Gas panel Exhaust Gas Neutralizer Ammonia Gas Dissociator H2 and O2 sensor 1 2 3 4 Exhaust gas neutrali zer Ammonia Gas Dissociator 5 4 1 2 3 4 5 6 6 II. 5. ALD’s solutions NiH furnace for Gas nitriding 14
  15. 15. I.Reasons for nitriding II.Gaz nitriding 1. How does gas nitriding work? 2. Structure of nitrided material 3. What kind of material can be nitrided? 4. How the gas process is controlled? 5. ALD’s solutions : NiH furnace for Gas nitriding III.Plasma nitriding 1. Plasma physics 2. How the plasma process is controlled? 3. Plasma nitriding technology improvement 4. ALD’s furnace solutions: Plasma nitriding conception IV.How to choose between the two technologies Outline 15
  16. 16. Plasma nitriding, known also as ion nitriding, is a form of case hardening process. It is an extension of conventional gas nitriding process, utilizing plasma discharge physic to diffuse nitrogen into the surface of a ferrous alloy. 16 III. 1. Plasma nitriding Introduction
  17. 17. Incoming electron Ejected electron Deviated incoming electron III. 1. Plasma nitriding Introduction to the physics E n Light emission Incoming electron Deviated incoming electron Light emissio n Excited electron 17
  18. 18. Low pressure H2 H H+ 𝐸𝑐 = 1 2 𝑚𝑉2 Cations bombardment s III. 1. Plasma nitriding Introduction to the process 18
  19. 19. • Temperature (400 to 600°C) • Pressure (0.5 to 10 mbar) • Gas composition (Nitrogen, Hydrogen, Methane, Oxygen, Argon …) • Time (1 - 120 hrs depending on case depth) • Voltage • Current • Power • Pulse duration (tON) • Pause duration (tOFF) Volta ge Time Voltage (- ) III. 2. Plasma nitriding process parameters 19
  20. 20. • Hollow cathode effect • Edge effect • Bad Temperature uniformity • Arcs Direct Current Plasma Nitriding DCPN Active Screen Plasma Nitriding ASPN The ASPN technology is covered by the ION2-cloud® patent owned by ALD III. 3. Plasma nitriding technologies 20
  21. 21. 1) Vacuum tight furnace 2) Pumping stand with pressure control (throttle valve) 3) Gas cabinet 4) Power and control cabinet 5) Plasma power supply cabinet 6) Closed‐loop water cooling systems 61 2 3 4 5 III. 4. ALD’s furnace solutions Plasma nitriding conception 21
  22. 22. I.Reasons for nitriding II.Gaz nitriding 1. How does gas nitriding work? 2. Structure of nitrided material 3. What kind of material can be nitrided? 4. How the gas process is controlled? 5. ALD’s solutions : NiH furnace for Gas nitriding III.Plasma nitriding 1. Plasma physics 2. How the plasma process is controlled? 3. Plasma nitriding technology improvement 4. ALD’s furnace solutions: Plasma nitriding conception IV.How to choose between the two technologies Outline 22
  23. 23. ■ Plasma is a low gas consumption process The amounts of gas used are about 90% lower than for gas nitriding ■ Plasma has a low environmental impact No harmful discharge released into the atmosphere - 99% removed Consumptions and emissions Plasma nitriding / Nitrocarburizing GAS PLASMA (%) REDUCTION Gas amount used m3/h 6.0 0.6 90.00 Total carbon emission via CO / CO2 mg/m3 137 253 504 99.63 Total amount of NOx gases mg/m3 664 1.2 99.82 Rejection of residual C carrier gas mg/h 823 518 302 99.96 Residual gas release NOx mg/h 3 984 0.72 99.98  Sources: Jean Georges, Jean-Paul Lebrun IV. How to choose between the two technologies 23
  24. 24. Gas Nitriding Plasma nitriding Easy loading Etching cleaning Part with complex shapes Sintered parts Very thick white layer No or very thin white layer Kn control> recipe and metallurgical results independent of the loaded part amount Very low gas consumption No ammonia Maintain stainless steel properties Easy installation of the furnace in a workshop Easy masking IV. Performances of: 24
  25. 25. Do you want more about nitriding ? Contact ALD France 73D Av. Général Mangin 38100 Grenoble, France  +33 (0) 476 33 64 40 info@ald-france.eu Sales :  +33 (0) 643 81 99 06 10 sales@ald-france.eu Visit us www.ald-france.eu Nitriding Lab’ Process definition Sample analyze 25

×