Boronizing

Boronizing (also known as boriding) is a thermo-chemical surface hardening process in which boron atoms are diffused into the surface of a work piece to form complex borides (i.e. – FeB/FeB2) with the base metal.  There is no mechanical interface between the complex borides and the substrate as this is a true diffusion process.  The resulting case layer has a hard, slippery surface capable of performing at higher temperatures than most surface treatments.  Practically any ferrous material can be boronized, as well as many Ni, Ti & Co alloys.  However, it is important to note, the higher the content of alloy elements, the slower the diffusion rate.

 

 

 

Some powder blends used in pack boronizing:

•% 60 B4C + %5 B203+ %5 NaF + %3O Iron oxide
•% 50 Amorph bor + %l NH4F.HF + %49Al203
•%100 B4C
•%(7,5-40) B4C + % (2,5-10) KBF4+ %(50-90) SiC
•%84 B4C + %16 Na2B407
•%95 Amorph+%5 KBF4
•%20 B4C + %5 KBF4+ %75 Graphite
•%(40-80) B4C + %(20-60) Fe203
•%80 B4C + %20 Na2C03
•%5 B4C, %90 SiC, %5 KBF4
•%50 B4C, %45 SiC, %5 KBF4
•%85 B4C, %15 Na2CO3 
•%95 B4C, %5 Na2B4O7
•%84 B4C, %l6 Na2B4O7
•Amorph bor (%95-97 B)

In particular boride layers show the following advantages: 

  1. High hardness of 1400-2400HV depending on the base material
  2. High layer hardness also on unalloyed steels
  3. Significantly improved adhesion compared to conventional hard material coatings
  4. High resistance against abrasive wear
  5. High resistance against adhesive wear
  6. Good stability at high temperatures
  7. Good resistance against meltings of Al and Zn 
  8. Good behaviour with respect to acids

 

 

Hardness of FeB phase  : 1600-2400 HV,

Hardness of Fe2B phase: 1600-2000 HV

FeB ise more brittle than Fe2B.

Wear resistance of Fe2B is higher.

 

 

*Boron concentration with depth in AISI 1040 steel  

 

 

 

*Samples boronized for 8 hours at  900°C.

 

 

Some typical applications for boronizing include:


    Tooling
  • Hot forging dies
  • Wire drawing dies
  • Extrusion dies
  • Straightening Rolls
  • Ingot molds
     
  • General Components
  • Nozzles
  • Plungers
  • Gears
  • Shafts
  • Rollers
    Oil & Gas Components
  • Production tubing
  • Valve components
  • Valve fittings
  • Metal seals
  • Coal/Oil burner nozzles 
     
  • Miscellaneous
  • Turbine components
  • Pump impellers
  • Ball valves & seats
  • Shaft protection sleeve
  • Guide bars