B-
COTE
is a proprietary boronising mix of salts which is available in three systems to
the users as liquid, pack or paste boronizing compounds, each of the systems
are explained below.
LIQUID
BORONIZING B-COTE MSB retort is
used to melt the salt. Excellent fluidity will be obtained at around 900Deg C.
Purging of air is enough and there is no need for either inert gas or nitrogen.
After the liquid boronising process it
is enough to soak the components in ordinary water for around half an hour to
remove the salt residuals, or could easily be removed either barreling or by
any other suitable method.
PACK BORONIZING: B-COTE PB the ˚materials to be
boronized are packed with adequate amount in a 0closed container. Depending on
the material and the alloy content of the element the temperature of the
process is decided. The best results are obtained around 920 ˚C for pack Boronising.
In this method there is no need for maintaining a special atmosphere like
purging of inert gas or nitrogen inside the muffle. The treated material is
easily separable from the salt.
Slurry or Paste type Boronizing:
B-COTE SPB this is supplied in
powder form and required quantity of water is to be added to form a slurry and
the paste is applied to the area of the job to be treated. In case of higher diffusion
required apply another coat after ensuring the first coat is in touch dry
condition; place the job in closed stainless preferably 310 steel or Inconel
container and the lid to have a pin hole for the trace moisture/gaseous vapor to
escape during heating. In our process, inert
gas purging is not required. After processing, the components are washed with
water and no salt stick is present on the job. The major advantage of this
process is the possibility for Selective Boronizing of the component.
Substrate
|
Constituent phases in the boride layer
|
Microhardness of the layer, HV or kg/mm2
|
Fe
|
FeB
Fe2B
|
1900-2100
1800-200
|
Co
|
CoB
Co2B
|
1850
1500-1600
|
Co-27.5 Cr
|
CoB
Co2B
|
2200 (100 g)
~1550 (100g)
|
Ni
|
Ni4B3
Ni2B
Ni3B
|
1600
1500
9900
|
Inco 100
|
…
|
1700 (200g)
|
Mo
|
Mo2B
Mo2B5
|
1660
2400-2700
|
W
|
W2B
WB
W2B2
|
~2700 (overall hardness
|
Ti
|
TiB
TiB2
|
2500
3370
|
Ti-6Al-4V
|
TiB
TiB2
|
3000 (100 g) (overall hardness)
|
Nb
|
Nb2B2
NbB4
|
2600-3000 (overall hardness)
|
Ta
|
Ta2B
TaB2
|
3200-3500
2500
|
Zr
|
ZrB2
Zr2B
|
2300-2600(overall hardness)
|
Re
|
ReB
|
2700-2900
|