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Nb (Niobium)

Nb Carbide is an environmentally-friendly material. Investigations of Nb carbides (NbC and Nb2C) characteristics and properties demonstrate such positive properties of such materials as high melting temperature (~3500°C), extreme hardness and high corrosion resistance.

Nb Nitride is also an environmentally friendly material. This type of ceramic coating is mostly used currently as a superconductor at low temperatures, as a detector for infrared spectrum and as a reflective coating. However, these coatings have many other interesting and useful properties, such as chemical inertness, excellent mechanical properties, high electrical conductivity, high melting point (2573°C), high hardness (~2400 Hv25) and wear resistance.

Currently existing methods of generating NbN protective coatings are very complicated, cumbersome and marginally effective technologies, which include Chemical Vapor and Physical Vapor depositions (CVD and PVD respectively), metallo-organic chemical vapor deposition (MOCVD), magnetron sputtering, etc. All these methods usually generate very thin surface coatings, in the range of 0.5-1.8 microns. Furthermore, these are adhesive coatings and must have a strong bond with the component surface to be effective, which is usually impossible to achieve.

Thorough research powered the development of SANOVA's new custom treatment technology LINTERNIOBIUM-N1, which will facilitate creation of durable diffusion protective Nb nitride surface layers on Nb components manufactured from commercially-pure Nb and Nb alloy C-103. Resulting microstructures and comprehensive results of this technology development effort are presented below and can be discussed with interested parties.


Micro-hardness

Micro-hardness (Hk500) and microstructure of surface layer (x500) of Nb C-103 alloy specimens after LINTERNIOBIUM-N1 processing @ 1500°C for 30 min.

Micro-structure of surface layer

Microstructure of surface layer (x25, x100 and x500) of the NbN case of the commercially pure Nb specimen after LINTERNIOBIUM-N1 processing @ 1500°C for 30 min.


Very positive results were observed after treatment at temperatures above 1200°C, with most notable results obtained after processing at 1500°C and 1600°C which represent limits for our temperature controlling system currently deployed on the LINTERLAB-i2 equipment:

  • @1500°C: Max. hardness - 5311 Hv50, NbN protective diffusion layer depth - 63 micrometers, entire diffusion layer thickness and hardness - 0.8 mm and 600-800 Hv500.
  • @1600°C: Max. hardness - 3759 Hv50, NbN protective diffusion layer depth - 270 micrometers, entire diffusion layer thickness and hardness -3 mm and 600-800 Hv500.

Even better results were obtained at higher temperature of 1750°C and duration of 30 min: Avg. micro-hardness value (Hv50) of NbN protective surface layer of 5000 to case depth of 160 microns, with entire surface layer micro-hardness of 1000v at case depth of 5 mm! These results indicate that SANOVA process increases not only surface layer hardness and consequently wear resistance, but substrate material strength as well.