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12AX7
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My stock is just as springy in current condition as it is annealed to orange heat.
It sands just fine, with wet SiC, but it also goes through a lot of sandpaper to get much progress. I might have a crappy brand of sand paper, but I
don't feel it's unexpected given the nature of this material...
A glance reveals "strength increases with grade number" from CP1 to CP4. In fact, a perusal of MatWeb reveals: CP4 is specified as around 80ksi
tensile yield, while CP1 is around 30. Likewise, Brinell hardness is specified as 250 vs. 120, respectively. CP1 seems to be the most pure grade.
6Al4V annealed is specified as 128ksi yield, hardness 334.
It's kind of hard to compare to steel, I'd have to guess CP1 is like mild steel, CP4 more like carbon steel, and 6Al4V more like alloy steel. But the
thing about steel is, it can be annealed quite easily, and even the alloy steels end up softer than this stuff, when annealed. Titanium is springy
when annealed, and it only gets worse with the higher grades. An awesome structural material for sure! Steel also can end up much harder, turning to
glass in an intermediate step. I think titanium is like carbon or alloy steel at a moderate temper (spring temper, roughly). Soft enough to bend
rather than break, but strong enough to be springy...and hard to work. There is one commonality: the purer alloys are softer!
Fleaker, I might want CP1 next time... 
Tim
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tentacles
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I stopped plating the PbO2 today, just a few minutes ago. Hard to say exactly how adherent it is, but it is VERY smooth! I ended up adding more NaF
dopant to my PbO2 tank, my dumb ass picked up the wrong bag - it was next to my bag of 325 silica. I don't think any more of it actually dissolved, as
NaF isn't very soluble. There was probably already a saturated amount left in the plating solution after the last two sessions.
I can't find the camera right now, but this anode looks good, there are a few pinholes which should not matter too much if the DTO did a good job of
sealing. I plated on about 1mm total, so about .5mm thick layer. I thought about plating on more, but I didn't really see the point of a massive
layer.
It's entirely possible that the only way to get a pinhole free LD plating is with a surfactant, or perhaps even the right surfactant.
I'm not sure if I want to test this one in KClO3 or KCl.
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dann2
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Hello,
| Quote: | Originally posted by tentacles
..... my dumb ass picked up the wrong bag - ............. |
Your dumb ass has amazing manual dexterity!!!!!!! 
| Quote: | Originally posted by tentacles
..... there are a few pinholes which should not matter too much if the DTO did a good job of sealing. ............. |
My take on the Ti/DTO is that the function of the DTO is to stop the LD from Oxidizing the Ti, not to protect the Ti from the electrolyte. The Ti will
protect itself from the electrolyte if it should come into contact with it by forming its protective Oxide coating.
If there are pinholes I suppose it may be possible for the electrolyte to travel along the Ti/DTO interface and ruin the anode that way, or perhaps
travel along the DTO/LD interface and cause seperation.
I wonder if (it's remenisent of the graphite!) if you were to put your anode into a container of sealer of some sort and pull a vacuum and then cure.
This would help put an end to any pin hole problems that may occur. Hopefully pin holes do not cause problems with this type of anode.
Only time will tell.
Perhaps KCl or NaClO3. If you use KClO3 the Perchlorate forming will encrust the anode (or so I believe).
Dann2
[Edited on 21-1-2008 by dann2]
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tentacles
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Well, in other news, I fumbled the ball, straight down onto the floor and a good portion of the LD cracked off (in sheets, interestingly). I did have
time to do some resistance testing (and clean out my 4L beaker/cell) and this looks promising. If I can find the high res camera I will take pictures
of the LD. From appearances, the pin holes DID NOT go all the way through the LD - they were only on the surface, no more than half way through. Most
of the resistance points (measured from a SS screw in the top of the Ti strip) were well under 100 ohms.
I have since done a light sanding on the anode, baked on another 3 coats of ATO, wiped and am replating with LD at 20ma/cm2. I started out at 3.5A
(~80ma/cm2) for 15 minutes to put a 'flash' plating of alpha PbO2 on there. It should be plated heavily enough by bedtime to take some pics. The
previous attempt was done at about 9ma/cm2.
[Edited on 21-1-2008 by tentacles]
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dann2
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Hello,
Oh no !!!!!!!!!
From my previous experience measuring the resistance of LD (the chemically deposited coats used to make ceramic conductive when making ceramic
substrate LD Anodes) it can be difficult to come up with a accurate measurement.
The 100ohms seems very very high.
Use a resistance measuring device that sends a decent current through the LD that you are measuring. Take a battery + resistor + meter combination
that sends a few milli Amps (as opposed to a few micro Amps with a modern meter) through the LD to measure the resistance.
Dann2
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12AX7
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I'm reminded of something wholly useless I did.
I had a moist sample of PbO2 powder in a jar. On a whim, I measured its resistance. Oddly, it showed something absurd, like more than infinity, or a
negative amount. Clearly, it's producing voltage. I switched over to DC and saw a volt or two. Probably the steel ground clip redoxing with the
PbO2, and the brass probe acting as an inert connection.
Tim
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tentacles
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I got my thermocouple today, took some measurements. With no restriction on the end of my tube furnace, I get 14.2mV, corresponding to 350C in my CRC
handbook. BUT this thermocouple reads 0mV at 20C(should be .79mV), so this may be as high as 360C (14.71mV). Restricted by placing a 1" piece of steel
bar on top (leaving the tube to either side venting freely), the heat goes up to 16.8mV, ~410C.
I'm almost done recoating that Ti strip, will subject it to PbO2 plating hopefully tonight, I have to pick up a freezer (future kegerator) tonight
though.
[Edited on 22-1-2008 by tentacles]
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quest
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plating in layers
I'm a little short of time for electroplating my PbO2 electrode.
I'm at home only for 2 days every week.
As far as I understood you can't plate for some time, let it rest for a week, and plate it some more. The layers won't adhere to each other.
So I thought maybe I can put the electrode in HNO3 or some other solution to make the outside layer active again.
Any ideas?
(plating for more than 2 days is unreachable for me)
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dann2
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Hello,
At 20 or 40 mA per square cm you will build up quite a thickness (some mm's) in a day.
What thickness do you want?
Are you plating on a substrate or massive?
I dont know anything about making the outside layer more active again. It is not a good thing (as you said) to stop and start again.
Dann2
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Twospoons
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Maybe you could leave it with a tiny trickle of current - just enough to keep the plating going, not so much you need to babysit the plating bath.
Helicopter: "helico" -> spiral, "pter" -> with wings
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tentacles
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I got my keezer yesterday, and today I was working on it but I did take a break to slop on a 4th coat of DTO (so 4Co/4DTO/PbO2) and dunk this thing in
the plating tank. I'm using low current again to try and replicate my first plating. I promised Xenoid I would weigh this one! And goddamn it, I DO
NOT want to drop this one. I lose more potentially good anodes this way :/
The irony is that I again forgot to weigh the pre plating anode. My other anodes are very close to the same size (I can weigh them all and average the
numbers).
Another question is, how thick of a PbO2 plating do we consider durable in an electrochemical sense? Does anyone know the (any) wear rates for PbO2?
[Edited on 23-1-2008 by tentacles]
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tentacles
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I checked on the anode today, the PbO2 bubbled and was peeling again. I have no idea why it's doing this, my best guess is my DTO solution is not
working properly anymore. Maybe I'll try one with just Co spinel.
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quest
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| Quote: | Originally posted by dann2
Hello,
At 20 or 40 mA per square cm you will build up quite a thickness (some mm's) in a day.
What thickness do you want?
Are you plating on a substrate or massive?
I dont know anything about making the outside layer more active again. It is not a good thing (as you said) to stop and start again.
Dann2 |
I'm going to try making masive anode like hashashan did, using hashashan's Ti plate. His anode took him 4.5 days of electrolysis, so I guess that 2
days will give me too thin anode. (This doesn't mean I won't try to run it for only 2 days anyway).
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hashashan
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Dude I'm giving you a smaller Ti strip because the big one is currently in use .. so As I'm thinking If you'll plate in a bit higher current density 2
days will be enough
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dann2
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Hello Folks,
Anyone know any refs. for Lead Tartrate LD plating bath.
I have GB850380
and JES Feb 1958.
The current density used in GB850380 is very small at 1.1mA per square cm.
No mention of CD in JES 1958
Is this the norm?
Dann2
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dann2
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Hello,
I eventually got around to LD plating.
I started with a Ti substrate that has had ATO applied to it about 2 months? ago. 5 coats ATO afaik.
A picture of the substrate is on the board somewhere, it is the substrate described as 'already ATO'ed'
A coating of Alpha Lead Dioxide was applied by using a Lead Tartrate bath. (I could not get Lead Plumbate bath to work for me as stated somewhere
else)
The Lead Tartrate bath was made up from:<br>
<ul><li>100 grams Potassium Sodium Tartrate </li>
<li>50 grams Sodium Hydroxide</li>
<li>96 grams Lead Oxide (Litharge)</li><br>
Dissolved as listed into 2 liters of water. The bath was heated to 60C to dissolve all Litharge. Any Litharge that did not dissolve was then filterer
(or decanted) off. The Litharge was ground with a pestle and mortar to get rid of the lumps that were in it.<br>
The actual bath size used for the anode plating was 600ml.
The bath was used at 70C with a current density on the anode of 1.2mA per square cm. Gentle stirring was used. The tank had to be topped up with
water on a regular basis as the level dropped due to evaporation. Ti cathodes (two) were used. The ATO coated Ti was plated for 22 hours to give a
thin coat of black Alpha LD. This coat, when viewed at 100X appeared as a mass of nodules not unlike looking at blackberries. The anode at this stage
weighed 22 grams and was 3.0 to 3.1mm thick and 9.8cm (active area) long (other dimension not measured).<BR></UL>
Next a coating of Beta Lead Dioxide was applied using a Lead Nitrate bath made up of:
<UL><LI>450 grams Lead Nitrate</li>
<li>6 grams Copper Nitrate</li>
<li>Nitric acid to put pH to approx. one (a few mls)</li>
All dissolved in 1 liter of water<br>
The actual bath size used was 800ml. Plating current was a steady 315mA.
A current density of approx. 17mA per square cm on the ATO'ed Ti was used at the start. At the end of plating, due to the increased size of anode,
the current density was 7.7mA per square cm. The temperature was 55C. Stirring was used with approx. 12 grams of Aluminium Oxide grit (abrasive grit,
sieve size 300 to 400) added in order to keep any bubbles that formed on the anode sweeped off. </ul><br>
Stirring had to be vigorous enough to keep grit in suspension. Ti cathodes were used. Evaporation was not so much of a problem but some additions of
water had to be made to keep the tank level constant. The anode was plated for 35 hours. A coating of Beta Lead Dioxide was obtained of thickness
1.5mm at top of anode and 0.95mm at the bottom. The thickness of the coating seems to change fairly abruptly where there were no holes in the
substrate. A total of 31 grams of Beta Lead Dioxide was deposited.<br>
The coating had a rough but shimmering texture. When viewed under 100X, faults were visible but it is not known of they penetrate deep into the Lead
Dioxide. The plating was not continued for long enough to totally fill in the drilled holes in the anode/substrate. The anode measured 10cm by 15mm
(14mm at bottom) by 6.1mm (4.9mm at bottom). This give an estimated surface area of 40cm squared.<br><p>
The anode will be put to work in a (Per)Chlorate cell at a current density of 300mA per square cm (12 amps) where it will hopefully work for at least
six months 24/7. <br><p>
Before using the above Lead Nitrate bath I tested it using a small piece of Graphite. I got a good, (perfect) coating to the naked eye. When viewed at
40X it was surprising how many pin holes (perfectly formed) there was in the coating.
Photo to follow.
Dann2
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chloric1
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Well, the faults and pinholes are demostrative why the ATO or MMO interface needs to be sealed so the oxidizing electrolyte does not penetrate and
passivate the Ti.
Fellow molecular manipulator
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dann2
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Hello,
You may be right.
We/I hope that when the solution enters the inevidable pinholes it will just corrode/wear away the DTO (or Co Oxide) and then just passivate the Ti in
the vincity of the pin hole. It will hopefully not travel between DTO (or Co Oxide or whatever interface is there) and Ti and passivate the whole
surface. If it does do this, then this type of anode will fail for in the amateur world (in general) as most of us (me anyways) are not going to set
up an LD plating process to give PERFECT coats of LD.
If people are willing to set up an elaborate LD plating process then there is nothing to stop the (horribly disappointing in the past) graphite
substrate anode etc from succeeding. I for one will not be doing it. The Ti anode with DTO + LD is hopefully going to be 'pin hole tolerent'.
Maybe not. At the end of the day only time is going to tell.
DTO will stand up for quite some time in a Chlorate or Perchlorate cell on its own. Co Oxide is not too good (bad in fact) in a Perchlorate cell (as
shown by Xenoid and others).
Dann2
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dann2
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Hello,
Picture of my first attempt at a Diamond Shamrock/Alembic Ti + ATO + Alpha + Beta LD anode. (as described above).
Camera not great.
Still have to put it in a cell ...or should I just leave it on the shelf and claim total success????????????/
Cheers,
Dann2 (AKA The Diamond Shamrock Diva :cool
[Edited on 6-2-2008 by dann2]
[Edited on 20-2-2008 by dann2]
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chloric1
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Hey there!
Nice anode! I would try this! What that? Yellow tape?
Fellow molecular manipulator
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hashashan
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definitly a materpiece a great LD coating.. very smooth... no bumps(how did you
do that BTW?)
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dann2
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Hello,
The yellow tape was on the substrate from another plating attempt. (Using Sodium Plumbate which was not successful). I just left it there. It is a
good way to give a ' sudden' end to the Lead Dioxide. You keep your plating tank level somewhere on the tape (level will vary but keep it on the
tape.) The Lead Dioxide will plate up against tape and you will not have a ragged edge.
@ Hashashan
There is a discription of how I made the anode a few posts up.
A picture of the substrate was posted in another thread.
All LD anodes usually look good. The test comes when they are used for a week/month/months.
Dann2
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dann2
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Hello,
I wrote up an account of making Ti substrate LD Anode using ATO interface layer here.
http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...
or to go up one tier
http://www.geocities.com/CapeCanaveral/Campus/5361/chlorate/...
Dann2
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tentacles
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I'm rather intrigued by dann's success using SnCl4 to make ATO coatings - I wonder if you couldn't dope with a different chloride as well? Maybe
BiCl3? Or even diffusion dope by layering, with a very dilute solution of dopant baked between layers of SnO2.
I'm thinking about picking up some SnCl4 and some PbO from chemsavers over on ebay. They've got the Cl4 for reasonable (considering it's 500g).
dann, how long has that been running for so far? Any idea how the adhesion is with the alpha undercoat?
edit: Chemsavers has their own site as well, with lower prices.
[Edited on 20-2-2008 by tentacles]
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chloric1
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Well dann2 I am quite pleased with your website. I must give you my thanks on your relentless pursuits. I still want to play with cobalt/mixed
spinels and MnO2 anodes for chlorate making but I now know how I want to try perchlorates. Also, you should be able to make other things with LD
anodes such as persulfates, bromates, etc. that woud be handy because you could make your own persulfate catalyst for producing perchlorates  .
I used boiling oxalic acid etching on the Ti6Al4V alloy and it worked but not with hot HCl. Still might use these rods but I want to try higher
grade alloys. I was unsure about using flat substrates but with some sanding and etching, the edges can be rounded enough to nullify any deposit
problems.
Have you had any success with Stannic chloride that you made yourself? Or your successes based on purchased stannic chloride? It might not always be
available on ebay in the future.
[Edited on 2/20/2008 by chloric1]
Fellow molecular manipulator
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