Magnesium
cases and covers
Keronite is specified
for the cast magnesium engine covers
and intake manifolds of the new Bugatti
supercar. These parts are partly exposed
at the rear of the car. This means
that they must have both good corrosion
protection and a high quality appearance.
Pistons
and cylinder liners
There are four or five areas where
Keronite can assist the performance
of aluminium pistons:
Top ring grooves
A key location on the piston,
this is subject to the force of
the top ring under full combustion
pressure. It is therefore subject
to high dynamic loads and wear.
In gasoline engines, aluminium
pistons are often hard anodised
in this region to prevent wear.
However, Keronite has been found
to give a factor of four or five
increase in top groove endurance
compared to hard anodising. This
is currently of most interest
in Europe and Japan where there
engines tend to be designed with
higher specific power than US
and elsewhere. Reduced wear in
the top groove means lower lifetime
emissions from the engine, so
it is an important factor to get
right. Additionally any piston manufacturing companies want to use Keronite to move the top groove closer to the crown to reduced crevice volume and therefore HC emissions. |
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As well as increasing
the top ring groove endurance, other
customers have identified that Keronite
is or may be useful in other applications
on the piston:
- On diesel pistons, one car maker
wants to use Keronite as a thermal
barrier on the crown instead of zirconia
spraying. Thermally-sprayed ceramics
cannot easily coat the complicated
piston crown geometry and also have
poor adhesion, especially during thermal
cycling. Keronite can give the capability
to overcome both these problems.
- On gasoline pistons, race teams
already use Keronite to protect the
piston crown from erosion/detonation
damage. Higher volume production has
now started for road-going engines.
- On diesel pistons, one may be able
to use Keronite as an alternative
to iron inserts for top ring grooves.
The motivation for this is to reduce
the moving mass of the piston (and
allow reduction in mass of other moving
parts like connecting rods and crankshaft)
and to increase thermal conductivity
and hence heat transfer from the piston
to the cylinder wall via the rings.
- Keronite can be considered as a
protective coating in the pin hole.
- Several customers are testing Keronite
on the piston skirt on both aluminium
and magnesium pistons. For example,
the Spanish company Tarabusi found
some very exciting results in the
EU Nanomag project – that Keronite-coated
magnesium piston skirts and pinholes
displayed low wear and friction: similar
to uncoated cast aluminium.
All the properties
that make Keronite a viable choice
for piston coatings – low friction,
high hardness, high adhesion, flexibility
– make it a possible choice
for cylinder liners also.
Keronite has teamed
up with Gramm
Oberflaechentechnik for the industrial
implementation of Keronite-coated
pistons and other automotive applications
where only a selected region of the
component requires surface treatment.
Gramm has many years of experience
in this area and today treats approximately
80 million pistons per year with hard
anodising or other types of electroplating.
This is a key strategic alliance for
both partners combining the excellent
properties of the Keronite coating
with the high-speed selective coating
expertise of the Gramm GST technology.
For more info contact info@keronite.com
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Aluminium
FEAD pulleys
Pulleys that form part of the
FEAD (Front End Accessory Drive)
of an engine are subject to wear
during a certain endurance test
employed by some manufacturers.
In this test, the engine is run
and sand is directed at the engine
a high velocities to simulate
desert driving. During this test,
sand particles are temporarily
trapped between the drive belt(s)
and pulleys, causing the pulleys
to wear. As a result of one test,
a typical steel pulley would lose
3 mm from its diameter due to
this wear. Such aggressive conditions
would normally preclude the use
of lightweight pulleys made of
aluminium. However, a Keronite
coated aluminium pulley exhibits
almost no detectable wear when
exposed to this test. This performance affords the use of Aluminium idler, camshaft, ancillary and crankshaft pulleys which in turn reduces all important reciprocating mass |
Aluminium
pumps
Oil, water, diesel and gasoline pumps
usually contain a small number of
moving parts, all of which move/rotate
at high speed and cause or are subject
to wear and/or corrosion. This can
apply to the pump rotors, shafts,
bushings or the housing. In such cases,
aluminium is often already used as
a weight saver for one or more of
the parts, but usually not all because
wear resistance is not good enough.
A thin layer of Keronite can be a
good surface treatment option to protect
the existing aluminium parts and can
also allow the steel counterpart to
be considered in aluminium.
All magnesium
engine
For some time a dream of certain parts
of the auto industry has been an all
magnesium engine. Much interest and
excitement surrounded the introduction
of BMW’s magnesium engine block
which is a triumph of engineering.
However, this still has an aluminium
water jacket and cylinder: the water
jacket through fears of corrosion
if it were magnesium and the cylinder
liner because magnesium would not
have the required surface hardness
to endure the piston wear and combustion
chamber pressure. With Keronite, it
may be possible to overcome such problems
and make a full magnesium block. The
USCAR programme is also studying an
all magnesium engine block. Keronite
is involved in multiple projects in
this area, including membership of
the USCAR programme. |