While I'm waiting for the titanium tubing to arrive ,
I'm reaearching about the titanium anodisation thing.
Recently I'tried the so called "Type II anodisation" or AMS2488 Ti anodising.
http://anodizetitanium.com/titanium-anodizing-tips-and-tricks/ams-2488-type-ii-titanium-anodizing/
It's quite different in many aspects from the "traditional " color anodising.
And kinda more tricky .
Anodic oxidation of titanium can be
identified and classified on the basis of the oxide characteristics:
- a “traditional” anodizing, whose result is a compact oxide
layer, up to a few hundred nanometers thick, which
often lends the metal a surface color.
- a more onerous process, which leads to a further thickening
of the oxide layer and its crystallization: the process
is referred to as Anodic Spark Deposition (ASD), or
Plasma Electrolytic oxidation (PEO), or MicroArc Oxidation
(MAO) because of the development of plasma
discharges on the surface.
Anodic spark deposition (ASD), also called microarc oxidation or plasma electrolytic oxidation,
diverges from traditional anodizing not in the procedure but in the process
parameters necessary to produce the microplasma state,
which are far more onerous than those required by the color anodizing procedures.
At first, a uniform amorphous oxide layer is formed on the titanium anode,
whose thickness increases with increasing feeding voltage ( ~ 2 nm /V ) and
creates a compact dielectric barrier that prevents ionic current from further
flowing through the oxide itself. If the breakdown voltage of the oxide is exceeded,
the barrier is overcome and the oxide keeps growing (dielectric breakdown).
Since the oxide obstructs the current flow, the whole available current concentrates in few oxide weak
points, as defects or localized stress states, where the dimorphology electric barrier is less effective: the electric fields reaches extremely high values in these points, so as to cause atom ionization and a localized microplasma state, with kinetic temperatures up to 7700 °C !!!
The dielectric breakdown is accompanied by a cracking noise and by the rise of small electric discharges defined as white tiny sparks, which last a few milliseconds and seem
to move along the whole surface, creating small electric arcs,
as sparking moves from one weak point to another;the discharges become greater as the process moves forward. The high energies involved in sparking causes the damaging of adjacent oxide areas which were still intact, and therefore cause the process to extend over the whole anodic surface.
Of course it's just amazing to see it happening in front of your eyes.
( Maybe I should try and upload a vid about it.You should see this while it's happening ! )
The part being oxidised (rather than anodised) that way has a powdery looking white coat ,
when the process is finished.That is usually removed with bead-blasting the surface.
I did it with a rotary felt wheel and some polishing compound.
At the pic below ,a ti tube oxidised to AMS2488.The oxidation was almost totally removed on the right with some 400 grit sandpaper ,to get a first evalutaion of the oxide layer.
Notice the white powdery coat.Underaneath thaty is the thick gray oxide layer.
And eventually I discovered someting about the Arizer Air.
Comes in a weird -but really nice- brownish-graish hue ...
Why on earth is named "Titanium" ?
It's the "mil-spec" gray .
A 4th gen Ti tip oxidised to "mil spec gray".Notice deep inside,between the fins
the whitish -powdery coat ,that the felt wheel was unable to reach :
**The stem is anodised with a new variation : the "Gel-Ti-dation " .
A thick hydrophillic ,gel-like ,layer of a metastable type crystallic titania ( mostly anatase )
is formed.Still at experimental stage .More info on a future post.
Cheers.
I'm reaearching about the titanium anodisation thing.
Recently I'tried the so called "Type II anodisation" or AMS2488 Ti anodising.
http://anodizetitanium.com/titanium-anodizing-tips-and-tricks/ams-2488-type-ii-titanium-anodizing/
It's quite different in many aspects from the "traditional " color anodising.
And kinda more tricky .
Anodic oxidation of titanium can be
identified and classified on the basis of the oxide characteristics:
- a “traditional” anodizing, whose result is a compact oxide
layer, up to a few hundred nanometers thick, which
often lends the metal a surface color.
- a more onerous process, which leads to a further thickening
of the oxide layer and its crystallization: the process
is referred to as Anodic Spark Deposition (ASD), or
Plasma Electrolytic oxidation (PEO), or MicroArc Oxidation
(MAO) because of the development of plasma
discharges on the surface.
Anodic spark deposition (ASD), also called microarc oxidation or plasma electrolytic oxidation,
diverges from traditional anodizing not in the procedure but in the process
parameters necessary to produce the microplasma state,
which are far more onerous than those required by the color anodizing procedures.
At first, a uniform amorphous oxide layer is formed on the titanium anode,
whose thickness increases with increasing feeding voltage ( ~ 2 nm /V ) and
creates a compact dielectric barrier that prevents ionic current from further
flowing through the oxide itself. If the breakdown voltage of the oxide is exceeded,
the barrier is overcome and the oxide keeps growing (dielectric breakdown).
Since the oxide obstructs the current flow, the whole available current concentrates in few oxide weak
points, as defects or localized stress states, where the dimorphology electric barrier is less effective: the electric fields reaches extremely high values in these points, so as to cause atom ionization and a localized microplasma state, with kinetic temperatures up to 7700 °C !!!
The dielectric breakdown is accompanied by a cracking noise and by the rise of small electric discharges defined as white tiny sparks, which last a few milliseconds and seem
to move along the whole surface, creating small electric arcs,
as sparking moves from one weak point to another;the discharges become greater as the process moves forward. The high energies involved in sparking causes the damaging of adjacent oxide areas which were still intact, and therefore cause the process to extend over the whole anodic surface.
Of course it's just amazing to see it happening in front of your eyes.
( Maybe I should try and upload a vid about it.You should see this while it's happening ! )
The part being oxidised (rather than anodised) that way has a powdery looking white coat ,
when the process is finished.That is usually removed with bead-blasting the surface.
I did it with a rotary felt wheel and some polishing compound.
At the pic below ,a ti tube oxidised to AMS2488.The oxidation was almost totally removed on the right with some 400 grit sandpaper ,to get a first evalutaion of the oxide layer.
Notice the white powdery coat.Underaneath thaty is the thick gray oxide layer.
And eventually I discovered someting about the Arizer Air.
Comes in a weird -but really nice- brownish-graish hue ...
Why on earth is named "Titanium" ?
It's the "mil-spec" gray .
A 4th gen Ti tip oxidised to "mil spec gray".Notice deep inside,between the fins
the whitish -powdery coat ,that the felt wheel was unable to reach :
**The stem is anodised with a new variation : the "Gel-Ti-dation " .
A thick hydrophillic ,gel-like ,layer of a metastable type crystallic titania ( mostly anatase )
is formed.Still at experimental stage .More info on a future post.
Cheers.
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