Cold,Hot-dip Galvanizing PTFE Zinc Nickel Inconel 825 Nickel Alloy
Fasteners
1.Difference hot-dip galvanizing and cold galvanizing
Galvanized Steel are those steel that has been covered with a layer
of zinc metal.
Hot-dip galvanizing, it is at high temperatures the zinc ingots
melt, being placed in the auxiliary material, then the metal
structure is immersed in a zinc plating bath, so that the metal
member attached to a layer on the zinc layer.
The hot galvanized advantage depend on its preservative ability,
the better the adhesion and hardness of the galvanized layer.
Cold galvanizing is a zinc salt solution by electrolysis, to the plating on the
coating, in general, which do not have heating, the amount of zinc
rarely encountered humid environment is very easy to fall off. The
cold galvanizing physical treatment, just in the surface brush a
layer of zinc, zinc coating so easy to fall off the use of hot-dip
galvanized construction.
Hot dip galvanized is immersed in liquid zinc dissolved workpiece
degreasing, pickling, dipping, drying a certain period of time and
put forward.
Cold galvanizing, also called electro-galvanized, is the use of
electrolysis device to the workpiece into the composition of the
zinc salt solution, after degreasing, pickling, and connecting the
negative electrode of the electrolytic device; zinc plate placed at
the opposite side of the workpiece is connected in the electrolytic
device the positive electrode, the power is turned on, a current
from the positive electrode to the negative directional movement,
it will be deposited on the workpiece with a layer of zinc.
Appearance of hot-dip galvanizing and cold galvanizing
Cold galvanizing looks more smooth, bright, color passivation
process plating layer is yellow-green in color, was colorful.
Plating layer was bluish-white or white with white passivation
process was green, white coating passivation process and the sun
was significant Colorful angle. The complex workpiece angular edges
parts prone to "electrical burning" from gloomy, the parts of the
zinc layer thick. Yin corner site is easy to form a current dead
undercurrent gray area and the area zinc layer is thinner. The
workpiece overall zinc tumor, caking phenomenon.
Hot dip galvanized look a little rough compared to the
electro-galvanized, silvery white, look prone process waterlines
and a few drops of tumor is more obvious, especially in the one end
of the workpiece. Hot dip galvanized zinc layer than a few times of
the electro-galvanized thick corrosion protection is several times
that of the electro-galvanized.
2.PTFE Coating Process
The term "PTFE" as used is intended to embrace both PTFE
homopolymers and polymers formed by copolymerising
tetrafluoroethylene with other monomers. Polymers of fluoroethylene
containing other halogens are also included, as are mixtures of
polymers of different composition. Polymers may be of different
chain lengths (molecular weights), molecular weight. If desired,
other particles, such as mineral particles of a pigmented
character, may be included with PTFE particles.
The bonding of the PTFE coating and the material of the substrate
is as a result of mechanical keying between the PTFE and the
surface of the substrate.
The PTFE particles are preferably less than 100 microns in
diameter, and more preferably less than 50 microns in diameter.
Particularly preferred are PTFE particles having a maximum diameter
less than 30 microns.
In conventional or air atomized spraying, the coating is supplied
to a spray gun by siphon, gravity, or pressure feed. When the gun
trigger is pulled, the coating flows through the nozzle as a fluid
stream. Compressed air from the centre of the nozzle surrounds the
fluid with a hollow cone as it leaves the nozzle, breaking the
coating into small droplets and transferring velocity to it.
Additional jets of compressed air from the nozzle break up the
droplets further and form an elliptical pattern.
In electrostatic coating, the fluid is atomized, then negatively
charged. The part to be coated is electrically neutral, making the
part positive with respect to the negative coating droplets. The
coating particles are attracted to the surface and held there by
the charge differential until cured.
With an electrostatic spray gun, the droplets pick up the charge
from an electrically charged electrode at the tip of the gun. The
charged particles are given their initial momentum from the fluid
pressure/air pressure combination. Electrostatic spraying offers
high transfer efficiency (65 % to 95 %) and excellent edge
coverage. The attraction between paint droplets and the part is
strong enough to cause paint overspray that misses the part to
curve back, which contributes to the high transfer effiencies.
Electrostatic application does not coat recessed areas (Faraday
cages) as well as nonelectrostatic application. The charged
droplets tend to be attracted to the sides of the recess and sharp
edges instead of penetrating to the bottom.
All electrically conductive materials near the spray area such as
the material supply, containers, and spray equipment must be
grounded to prevent static buildup. All hangers, conveyors, etc.
must be kept clean to ensure conductivity to ground. Charges build
up on ungrounded surfaces. Operators grounding out these surfaces
may receive a severe electrostatic shock.
Conventional air spray is the oldest spray process. It offers the
best control of spray patterns and degree of atomization. This
system produces the finest atomization and, therefore, the finest
finishes. Conventional spray will also spray the widest range of
coating materials of the four techniques.
The PTFE particles may be delivered to the surface of the
applicator in the dry state, but it has been found to be more
convenient to "deliver the PTFE particles to the surface of the
applicator in the form of a liquid dispersion. Preferably, the
dispersing solvent is sufficiently volatile to evaporate almost
instantly, leaving the particles in a substantially dry state, A
suitable dispersing solvent is trichlorotrifluoroethane, though
other low-boiling halogenated hydrocarbons can also be used.
PTFE is extraordinarily resistant to chemical attack, and the
surface free energy of solid PTFE is very low. This means that
liquids do not readily wet the solid, and other solids do not
adhere strongly. These properties render PTFE very valuable for
forming protective surface coatings, in a wide range of
applications from non-stick cookware to engineered products.
Methods employed for coating with PTFE is to spray onto the
substrate a dispersion of low molecular weight solids of PTFE
suspended in a suitable liquid such as solvents or water, known as
the carrier and then to evaporate the carrier. Such coatings are
sometimes sintered or even buffed in order to increase the
uniformity of the coating. However, coatings formed by this method
can be used as a single coat application such as in mould release
applications or as release layer. The method of application can be
applied to a wide range of substrates, and produces a type of PTFE
coating which is both tough and durable. Some PTFE coating systems
can be of a multi coat type, which includes both primers and mid
coats being applied before the final coat. Typical film thicknesses
are from 10 to 100 microns thick, for example from 20. to 50 nm
thick. . A usual characteristic of the process is that the aqueous
PTFE coatings are effectively self-limiting in thickness. However,
PFA (powder) coating can be deposited with additional thickness.
3.Nominal Length L12
Screw Thread d | M2 | M2.5 | M3 | (M3.5) | M4 | M5 | M6 | M8 | M10 | M12 | (M14) | M16 | (M18) | M20 | (M22) |
|
P | Coarse Thread Pitch | Fine Thread Pitch | Fine Thread Pitch |
| 0.4 | 0.45 | 0.5 | 0.6 | 0.7 | 0.8 | 1 | 1.25 | 1.5 | 1.75 | 2 | 2 | 2.5 | 2.5 | 2.5 | - | - | - | - | - | - | - | 1 | 1.25 | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 | - | - | - | - | - | - | - | - | 1 | 1.25 | - | - | - | - | - |
|
Weight of per 1000 steel products(≈kg) |
| 0.22 | 0.36 | 0.53 | 0.72 | 0.93 | 1.49 | 2.12 | - | - | - | - | - | - | - | - |
|
Screw Thread d | M24 | (M27) | M30 | (M33) | M36 | (M39) | M42 | (M45) | M48 | (M52) | M56 | (M60) | M64 | (M68) | M72 |
|
P | Coarse Thread Pitch | Fine Thread Pitch | Fine Thread Pitch |
| 3 | 3 | 3.5 | 3.5 | 4 | 4 | 4.5 | 4.5 | 5 | 5 | 5.5 | 5.5 | 6 | 6 | 6 | 2 | 2 | 2 | 2 | 3 | 3 | 3 | 3 | 3 | 3 | 4 | 4 | 4 | 4 | 4 | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - |
|
Weight of per 1000 steel products(≈kg) |
| |
Nominal Length L16
Screw Thread d | M24 | (M27) | M30 | (M33) | M36 | (M39) | M42 | (M45) | M48 | (M52) | M56 | (M60) | M64 | (M68) | M72 |
|
P | Coarse Thread Pitch | Fine Thread Pitch | Fine Thread Pitch |
| 3 | 3 | 3.5 | 3.5 | 4 | 4 | 4.5 | 4.5 | 5 | 5 | 5.5 | 5.5 | 6 | 6 | 6 | 2 | 2 | 2 | 2 | 3 | 3 | 3 | 3 | 3 | 3 | 4 | 4 | 4 | 4 | 4 | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - |
|
Weight of per 1000 steel products(≈kg) |
| |
Screw Thread d | M2 | M2.5 | M3 | (M3.5) | M4 | M5 | M6 | M8 | M10 | M12 | (M14) | M16 | (M18) | M20 | (M22) |
|
P | Coarse Thread Pitch | Fine Thread Pitch | Fine Thread Pitch |
| 0.4 | 0.45 | 0.5 | 0.6 | 0.7 | 0.8 | 1 | 1.25 | 1.5 | 1.75 | 2 | 2 | 2.5 | 2.5 | 2.5 | - | - | - | - | - | - | - | 1 | 1.25 | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 | - | - | - | - | - | - | - | - | 1 | 1.25 | - | - | - | - | - |
|
Weight of per 1000 steel products(≈kg) |
| 0.30 | 0.48 | 0.71 | 0.95 | 1.24 | 1.98 | 2.82 | 5.10 | - | - | - | - | - | - | - |
|
Nominal Length L20
Screw Thread d | M24 | (M27) | M30 | (M33) | M36 | (M39) | M42 | (M45) | M48 | (M52) | M56 | (M60) | M64 | (M68) | M72 |
|
P | Coarse Thread Pitch | Fine Thread Pitch | Fine Thread Pitch |
| 3 | 3 | 3.5 | 3.5 | 4 | 4 | 4.5 | 4.5 | 5 | 5 | 5.5 | 5.5 | 6 | 6 | 6 | 2 | 2 | 2 | 2 | 3 | 3 | 3 | 3 | 3 | 3 | 4 | 4 | 4 | 4 | 4 | - | - | - | - | - | - | - | - | - | - | - | - | - | - | - |
|
Weight of per 1000 steel products(≈kg) |
| |
Screw Thread d | M2 | M2.5 | M3 | (M3.5) | M4 | M5 | M6 | M8 | M10 | M12 | (M14) | M16 | (M18) | M20 | (M22) |
|
P | Coarse Thread Pitch | Fine Thread Pitch | Fine Thread Pitch |
| 0.4 | 0.45 | 0.5 | 0.6 | 0.7 | 0.8 | 1 | 1.25 | 1.5 | 1.75 | 2 | 2 | 2.5 | 2.5 | 2.5 | - | - | - | - | - | - | - | 1 | 1.25 | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 | - | - | - | - | - | - | - | - | 1 | 1.25 | - | - | - | - | - |
|
Weight of per 1000 steel products(≈kg) |
| 0.37 | 0.60 | 0.88 | 1.19 | 1.55 | 2.48 | 3.53 | 6.37 | 10.0 | - | - | - | - | - | - |
|
