REFRACTECH BORON NITRIDE COATINGS
General
Description
Boron Nitride coatings are manufactured
from Boron Nitride powders and high temperature binders.
These coatings are an economical method
of obtaining the benefits of using Boron Nitride such as:
x
Non wetted by most molten metals,
salts, fluxes and slags and drosses.
x
Excellent thermal shock resistance.
x
Excellent corrosion resistance.
x
Lubricity.
x
High electrical resistivity.
Performance
in Service
Boron Nitride coatings can be applied
to a variety of porous and non-porous materials including metals, graphites,
ceramics and organics. They will provide the following performance advantages
in service:
- increased corrosion resistance of
graphites and oxide refractories in metallurgical applications such as
aluminium, copper, magnesium and titanium processing.
- improved high temperature electrical
insulation.
- a reduction in sticking and
reactivity in glass forming applications.
- high temperature lubrication
properties for hot pressing, forging, and extrusions.
- excellent mould release properties.
- improved oxidation resistance.
Features
BNSP-W
Boron Nitride water based coatings in
different Boron Nitride contents for different applications such as:
-
Aluminium extrusions
-
Non ferrous foundries: aluminium,
magnesium, zinc
-
Glass bending
-
Superplastic forming
-
Welding, brazing and soldering
Key
Attributes of BNSP-W:
-
non wetted by molten aluminium,
magnesium, zinc
-
protects ceramics, metals and graphite
-
maintenance is reduced
-
dilutable to any level
-
applied like housepaint
-
thermal shock resistant
BNSP-A
Boron Nitride alcohol
based coatings. Same applications as a BNSP-W coating but with a higher drying
speed.
Application
Data
Boron Nitride
Coatings can be applied by brushing, dipping or spraying and are easily diluted
with water to achieve the desired consistency. The following table details
recommended guidelines for the three methods.
|
|
Spraying |
Brushing |
Dipping |
Curing |
|
BNSP-W |
Apply layers 0.025mm thick. Air cure for 20
minutes between layers. Maximum thickness 0.2mm. Spray at a distance 150 to
300mm |
Air dry 20-30 minutes between layers. Maximum thickness 0.2mm. |
Apply as received and as a single layer. Maximum thickness 0.075mm. If peeling occurs the
coating should be diluted with water. |
Air dry for 6 hours then at 90 deg C for 4 hours.
Can be polished with a soft towel or cloth. Heat at 450 deg C for 2 hrs to
increase hardness and permits application of additional layers. |
|
BNSP-WM |
Apply layers 0.05mm thick. Air dry for 20 minutes
between layers. Maximum thickness 0.25mm. Spray at a distance 150 to 300mm |
Air dry for 30 min. Between layers. Maximum
thickness 0.25mm |
Dilute coating as received with distilled water.
By volume, 5 parts water to 2 parts coating. If peeling occurs dilute to 3 to 1. Air dry 45 minutes between
layers. Maximum thickness 0.25mm. |
Air dry for 2 hrs then at 90 deg C for 4 hrs. Can
be polished with soft towel or cloth. Will not become harder with higher heat
treatment. |
Availability 1kg and
5kg containers Shelf life - 12
months
In order to maximise
the benefits of using BORON NITRIDE COATINGS it is important to follow our
recommended application instructions which detail surface preparation,
application and curing.
Technical Data on Boron Nitride Coatings
|
|
BNSP-WL5/25 |
BNSP-WM15/25 |
BNSP – WH20 |
BNSP-A |
|
Active
ingredient |
Boron
nitride |
Boron
nitride |
Boron
nitride |
Boron
nitride |
|
Binder |
alumina |
silicate |
phosphate |
Cellulose/ hectorite |
|
Purity
(%BN) |
98 |
98 |
98 |
98 |
|
Max
Use temp. |
900
oC air 1400
oC vacuum 1800
oC inert |
900
oC air 1400
oC vacuum 1800
oC inert |
900
oC air 1400
oC vacuum 1800
oC inert |
900
oC air 1400
oC vacuum 1800
oC inert |
|
Hardness |
low |
low |
medium |
low |
|
Adherence |
medium |
medium |
high |
medium |
|
Liquid
carrier |
water |
water |
water |
Ethanol/acetone |
|
Percent
active ingredient (%BN) |
5 10 20 25
|
15 25 |
20 |
25 |
|
Specific
Gravity (g/cm3) |
1.03 1.07
1.10 1.18 |
1.10 1.20 |
1.20 |
0.95 |
|
pH |
~6.0 ~5.0
~4.0 ~3.0 |
7-8 |
1.5-2.5 |
- |
|
Dried
composition (% solids) |
8 14 25 31 |
18 29 |
33 |
29 |
|
Viscosity
(cps) |
~500
~1000 ~1000 ~1500 |
~5000 ~10000 |
~10000 |
~800 |
|
Coverage
(m2/l) |
5-15
|
5-15 |
5-15 |
5-15 |
|
Colour |
white |
white |
white |
white |
|
Shelf
Life (months) |
12 |
12 |
12 |
12 |
The
values given are typical average values. They do not represent a specification.
Coverage values depend upon coating thickness and substrate porosity and
roughness.
Uses
-
ceramic troughs - dross press heads -
permanent moulds
-
ladles -
ceramic runners -
ceramic stalk tubes
-
immersion tubes - filter bowls
-
skimmers - aluminium extrusion
Application
Recommendations of the Boron Nitride Grades Available
(A) BNSP-WL series:
BN grades formulation, using alumina as
a binder and different Boron Nitride concentrations for general purpose
coatings. A higher Boron Nitride content assures a better performance in
tougher working conditions. These grades contain an acid to stabilize the
alumina binder system and is necessary to obtain coating durability.
BNSP-WL5:
The lowest BN concentration product
especially formulated for the aluminium extrusion process. Ready for use. A
thin Boron Nitride layer is guaranteed.
BNSP-WL10:
Same coating properties as WL20 type.
Ready to use for dipping or other applications that need a diluted product.
BNSP-WL25:
Thickest version of this type of
coating. Very versatile paint and can be brushed on to provide a thicker
coating.
Application
Recommendations of the Boron Nitride Grades Available (cont)
(B) BNSP-WM series:
BN grades formulation, use of silicates
in the binder system. It assures a high adherence in general applications. Also
when it is not convenient a low pH. These products have a neutral pH.
BNSP-WM25:
The thickest version available.
BNSP-WM15:
Same coating properties as WM25.
Thinner layer.
(C
) BNSP-WH series:
BN grades formulation with a high Boron
Nitride powder content and using phosphates as a binder that assures an
extremely high adherence. Specially recommended to be used in glass bending
process.
These products have an acid pH.
(D) BNSP – A series:
BN grade formulated with alcohol as a
carrier. Use when the customer wishes for a faster drying paint. Specially
conceived to use in superplastic forming process.
STORAGE
BNSP coatings should be protected from
freezing. Previously frozen product is not usable. A storage temperature of
>5oC is recommended.
HANDLING
Avoid prolonged exposure to skin. MSDS
available.
PACKAGING
All Refractech Boron Nitride Coatings
are packaged in plastic pails of the following weights:
BNSP-WL5/10 5 and 25kg
BNSP-WL20/25 1 and 5kg
BNSP-WM15/25 1 and 5kg
BNSP-WH20 1 and 5kg
BNSP-A25 1 and 5kg