Metallization
Due to the flexible and dynamic resources of the department, with the different tecnique used (HVOF and thread metallization) it is possible to treat a large range of components differing in size, weight, shape and contribution. Common factors that treated components have are: particulary corrosive work environment and wear or the need of refurbishment.
In order to guarantee the safety of the job, the repeatability and quality of the coating, the metallization pistol is mounted on an anthropoid robot, in an acoustically isolated cabin fitted with a smoke suction system.
Using two different diffractometers, one for the residual stress and one for the powders, 2Effe Engineering are capable of verifying the phase analysis of the coating (and the powders) and of evaluating the existing residual stress livels on the coating carried out.
For specific components that require elevated finishes it is possible to exploit the synergy with the lapping (reaching Ra<0.4) or correcting the areasof interest.
A new metallic thermal spray plant with high velocity oxy fuel (HVOF) technique; it can improve the surface characteristics and increase the resistance in corrosive atmospheres, increasing component longevity and profitability. The coating presents these characteristics:
These advantages are obtainable without modifying toughness and structural characteristics
of the substratum. In comparison to brazing and other thermal spray techniques
(for example Plasma Technique), the HVOF technique uses more kinetic energy
and less thermal energy; in fact, this particular consents a reduction of the
oxidization of particles during the operation. The high velocity of fuel guarantees
that the particles, especially those not completely fused, are deformed with
the impact on the substratum; this particular reduces the porosity of the coating
and increases the adhesion.
The process uses a combination of fuel, usually kerosene or propane, propylene,
hydrogen; the kerosene burns with an elevated percentage of oxygen producing
a flame with a speed of over 2000 m/sec. In this way the fused particles of
the material of coating are accelerated at the velocity of 1000m/sec toward
the substratum where they immediately solidify creating with the kinetic energy
a foliated structure (splat). This process offers the possibility of treating
a large range of components of various dimension, weight and form, that operate
in corrosive atmospheres or that need to returned to their nominal dimension.
HVOF is a simple technology and it is possible to carry out the operation off
the firm premises.
HVOF fuel
For a careful use of the system and to increase the work safety, the HVOF gun is mounted on a anthropomorphic robot in a separate box. This configuration also increases the repeatability and quality of the manufacturing.
HVOF gun on robot
With this technology 2Effe can make a very effective coating with various chemical compositions and mechanical characteristics:
| Chemical
composition |
DPH300 |
Porosity |
Temperature
maximum |
| WC-Co |
900-1150 |
0.5% |
530 |
| WC-Co-Cr |
1050-1400 |
1.1% |
750 |
| Wc-Cr3C2-Ni |
900-1000 |
1.6% |
750 |
| Wc-Ni |
850-950 |
1% |
540 |
| Cr3C2-Ni-Cr |
700-800 |
1.5% |
800 |
By using two different types of diffrectometers, one for residual stress and one for powders, 2Effe Engineering is able to check the crystalline phases of coating (and powders) and to value the residual stress.
To reduce superficial
roughness of the shell and the coating area, 2Effe can use lapping
(we can arrive at Ra < 0.40 µm) and grinding is also possible.
Thanks to an acetylenic flame implant it is possible to deposit all the available metals in a thread format, from standard steel to molybdenum for example.
The characteristic of this implant is the possibility of varying the hardness of the coating, thus obtaining layers with different properties for different applications: from "bond" to "hard" coating for wear resistence.