Silicon Nitride coated lash caps?

[Piledriver]

Jake, has there been any thoght of SiN or DLC coated lash caps?

For the folks with stock rockers w/10mm screws, these should eliminate the adjuster wear issues and be cheap as chips.

One could do hundreds at a time... Only one surface needs coated.

It's probably a better alternative than the ceramic tipped screws that were discussed at one point, and they's fit anything that uses 8mm stem valves.(or whatever sizes were coated)

[Piledriver]

Another interestic article (big PDF) sourtest of US Govt. research, covers various ceramics and laser dimpling effects.

http://www.ms.ornl.gov/programs/energye ... nitride%22

The laser dimpling reduced friction by... LOTS.
(oil lubricated SiC on SiC went from a CF of ~.10 to .01...)

This has been previously been suggested for use on piston rings, but it could be done on coated jugs as easily, with better effect.

[MASSIVE TYPE IV]

I have already done the DLC treatment to lash caps- it does work very well...

Silicon Nitride is so hard to get a hold of that development with it isn't even smart these days- almost a total waste of time.

[Piledriver]

Anyone doing DLC should be able to do SiN thin films...

Not bulk SiN--Thin films are Completely different processes. The bulk stuff is pressed in powder form and sintered, and is actually (probably) much harder to make.

Thin films are either a mix of gasses and (usually) RF (CVD) or sputtered on (PVD).

The thin film coating uses essentially the same equipment for DLC or SiN, and thin-film SiN is a staple in the semicondutor industry, from where all the coaters equipment evolved.(and in some cases was used originally, I'm certain)

Everyone and their dog should be able to do Silicon Nitride thin film coatings...

Perhaps they aren't proprietary enough?

[raygreenwood]

Piledriver.....Arn't those thin type films usually done through diffusion/kiln process? Those should be pretty common off-shoots of the semi-conductor industry. Ray

[Piledriver]

Piledriver.....Arn't those thin type films usually done through diffusion/kiln process? Those should be pretty common off-shoots of the semi-conductor industry. Ray

In the semi industry, Silicon Nitride is USUALLY done as a CMP stop layer, or as the final "top coat" passivation layer to seal the finished device.

The high temp diffusion furnace stuff is typically either for making a good quality native oxide (quartz AKA SiO2) or doping.

It is _almost_ always done with Ammonia and Silane (or /+ N2O?) gasses in a plasma (PECVD)... A second RF bias signal can be used to compress the SiN as it is being deposited via ion bombardment.

By balancing the gas stoichiometry and the bias, one can deposit virtually stress-free SiN that is far denser than the pressed/sintered bulk material.

PECVD SiN or DLC is also conformal...

Another method is plasma sputtering (PVD), as we discussed in another thread. This could be done in several ways, one with a consumable SiN "nozzle" on a plasma "torch" (under vacuum)
Would be very fast, compared to CVD at least.

I suppose one could do a reactive sputtering setup with a silicon target and an N2/Ar mixture and literally MAKE SiN enroute to the sample (probably how the bulk material is made)

Mind, the above methods are typically only suitable for THIN films of SiN... a few microns thick, perhaps up to 10...

But the main thing is that the mechanical properties of thin films are frequently grossly different than bulk material...

Stuff is frequently(typically...) orders of magnitude stronger,tougher, and more flexible as a thin film.

[914fan]

Diffusion AHHHHH! Photo AHHHHH! Its the yellow lights I tell you!!! There making all the particles attack me!!!!!


A Strange smoc covered man enters the room
" Theres no need to fear! Particle Man is here!!!"


Whoa what memorys. Pile I hope that if you are in that industry, that you are an engineer, or technition. I hope you are not running the ovens, etchers, polishers, or photo machines. Been there, done that!
Nick

[Piledriver]

Equipment Maintenance tech.

Thank goodness my current company doesn't use those furnaces-- they sucked to work on in so many ways...

[raygreenwood]

Yeah...at my last company...the diffusion department was "doping" wafers in thicknesses upwards to maybe 250-300 angstroms. Mostly N02 atmosphere. Sputter plating (which we did a lot of)....was too thick for what we are speaking of here. That was mainly used for pre-etch build ups of layers that were used for bridging large +/- areas. Mostly silane atmosphere. There is tons of that equipment laying around surplus. Ray

[Racer Chris]

All this talk of sputtering reminds me of an old job I had. I sometimes had to deposit a thin layer of gold onto mounted and polished samples I was going to look at in an electron microscope. That was done with no atmosphere at all.
I had lots of fun in those days.