kareina

When I woke up this morning the Alps were visible from my apartment. This is always a good thing, and had me start the day in a good mood, despite waking up kind of early in relation to when I went to sleep. Since it was also early with respect to the sun, which was still hiding below buildings and not causing much heat yet, I celebrated by going for a short walk. The walk came with a reward, as I passed a pile of good condition empty boxes that someone had flattened and left out near their trash; I've been needing more boxes to pack up the last of clovis_t's books, so I happily took them home with me. After the walk I took a short nap, and then went down to the lab, since today was the day I was scheduled to download the experiment that has been running for about 455 hours.

This involved meeting a co-worker for help, so I checked in with him, and he said that he'd be free in about an hour. Since it generally takes about that long to weld the powder into a new capsule, I set to the task. I had originally hoped to have two new capsules ready by the time this experiment ended so that I'd be ready to start the next one (we run two capsules in every experiment). Alas, my last two attempts at capsule welding ended in failure (which was most disappointing since five in a row before that worked perfectly on the first attempt). Today, though I worked slowly and carefully and was convinced I'd cleaned away all of the powder before pinching the ends of the capsule shut, still it managed to split open during the final weld, and the hour's work was for naught.

Once I'd cleaned up the tools my colleague was ready to help me download, and as we worked he asked "is this your last experiment till September?" I replied that I had hoped to have another ready to go by now, but the capsules have been splitting open on the weld, which is frustrating when they had been working so well a few weeks back. He then commented that it is always harder to weld during the summer, that the increased heat/humidity causes the powder to sick more than usual, meaning that the welds tend to split open. This news was strangely comforting, though I wish someone had mentioned this before! Thinking back on it, I first learned how to weld during last summer, when it was hot and humid, and found it to be very difficult. Then, over winter, I learned the trick of it, and got to the point where it nearly always worked, and then this summer, ever since it has gotten hot, I've been failing at what should be a doable task.

With this new information I promptly agreed that, yes, it is in fact, my last experiment till September, and I happily gave myself permission not to try welding again till it cools off! We finished downloading, and I extracted the capsules from their nest and went looking for the guy who mounts them into epoxy. He wasn't in, but it was close enough to mid-day that he could have been at lunch, so I headed back towards my office intending to look again later. On the way I ran into another couple of colleagues, and stopped to talk to them. Then I asked if they knew if the missing man is meant to be here today, and they let me know that there is a notice posted in the lift detailing the dates each of the support staff are taking their summer holidays. Since I always take the stairs I hadn't seen the notice. We checked, and sure enough, the guy will be gone all month. But my colleagues know where to find the recipe for mixing epoxy, and agree to meet me tomorrow to take care of that step with me, so if all goes well I can have this experiment ready for next week's microprobe session.

Since I was on a roll I then did more research on the funding application I want do submit for a research project and then this evening actually settled in to doing work with my current data. However, I did have to head home twice today for icy showers to make it possible to keep working in the heat. As a result I am pleased to report that I actually managed 8 full hours of work today, though it took from 7 am to 10 pm to manage it.

Now it is getting late and there is still yoga to be done, so I should probably head home and see how my houseguests are doing. Yesterday and the day before I didn't work in the evenings (which is normally my most productive time of day) because I'm hosting two delightful folk, one from Scotland, the other from California.

I welded it! I welded it! That capsule is SHUT! Totally air tight, and there is no shadow of doubt about it whatsoever! I've been struggling with this skill for a while now. Step one in setting up my experiments has become routine--take a piece of gold tubing 2mm in diameter and cut off a 7 mm length of it, pinch one end shut into a triple-junction, and weld that shut. But the next part, which involves adding a measured amount of water (and putting the holder + capsule + water onto the scale and making note of the combined mass), then adding the powder (again making note of the combined mass) such that the water is 5% of the total, then adding a sliver of graphite (again taking note of the mass) and then carefully cleaning the end of the gold tube so that not one speck of the powder nor any other contaminant remains, and then pinching it shut and welding it has been a problem.

In part because this second weld needs to be done with the capsule "cooled" during the process. This means that we set a small beaker full of water under it, and carefully arrange wet tissue paper fore and aft, in contact with the full part of the capsule, so that the welding process doesn't cause the internal water to boil out before it is sealed shut. In part because I've had problems getting the voltage exactly the correct setting on our old, jury-rigged, welding system, and in part because the bad welds I'd been doing have required carefully trimming of the end of the capsule, and trying again, which, if all isn't well, can cause the part I'm welding to be low enough in the capsule that some of the powder is caught between the pinched parts of the area I'm trying to seal, causing the melting to get down to that level, and the whole thing to open up to reveal the now molten powder. This happened again tonight, on my first attempt.

But I resolved to try once more, and pulled out a second ready to fill capsule. I added the water. Check. Added the powder. Check. Not quite enough powder, add a bit more. Check. Added the graphite. Check. Thought about it, and after very, very careful packing down of the powder and cleaning of the top portion of the capsule I moved the pliers lower than I had been, so that a millimeter or two stuck out above the width of the pliers. Then I carefully pinched the tube shut, confidant that the powder is located at least the full width of the pliers away from the end of the tube. Then I took the capsule to the large clamp and very carefully placed only the outermost bit of the pinched end of the tube into it and cranked it shut. This is called a cold-weld, and some labs stop here, not caring if their capsule is truly sealed. But we care here. So then I very carefully trimmed the very end of it off, making an even tighter, narrower end to weld. Then I applied the welder. I still don't have the hand-eye coordination to do the whole length of the weld at once (I think I'm still jumping back away from it when the flash of light and noise of the welding happens), but the first pass sealed one end with a beautiful bead. Try again from the other end. Another beautiful bead. But the middle is still un-melted. Oops, they recommend always working from the end towards the middle. Oh well, one last try, and it worked! The whole end of the capsule is a beautiful bead, totally smooth and looking exactly like it should! I was so pleased that I literally broke into song, making up a tune to the words "It's shut! I welded it", and variations thereof. Now I'm going to celebrate by heading home early (it is only 8pm!), and in the morning I'm off to the Alps for a gentle hike with some new friends.

Stayed up far too late last night. Spent the first part of the evening playing in the kitchen. First I kept clovis_t company (and assisted occasionally) as he made a meat/pasta/tomato/cheese dish for his evening meal, then I cooked up some of the veg I'd obtained at the market that morning for my ( lunch today )

After we'd gotten the kitchen cleaned back up again I did a bit more uni work before yoga, and then stayed up even later chatting. Finally went to bed some time after 01:00, which might have been fine, but about 05:30 some passing car/truck/whatever made an unusual noise that happened to wake me, and I didn't fall straight back to sleep, so I got up and did more uni reading. Got sleepy again about 7:00 and went back to bed for a "nap", and didn't wake again till 10:00. Despite having cooked lunch the night before, it still took a full hour to do my morning situps/pushups/etc., get showered, dressed, pack lunch, pack the computer, and actually walk the couple of blocks to uni, where I spent the morning feeling sleepy and not accomplishing as much as I would have liked. clovis_t wandered into town to do touristy things (feeling much better rested than, having actually slept uninterrupted from 01:00 to 10:00).

I was still feeling tired at lunch, which I have with my colleagues on my research team each day, but after lunch my boss turned me lose in the lab, where he taught me what I needed to know to do my first practice welds. Playing with the toys woke me right up!

What am I welding? Gold! The experiments we do here involve encasing powder of known composition into sealed capsules and then subjecting them to elevated temperature and pressure for long enough to grow minerals. The largest diameter capsules we use are 3 mm wide. This is the size I was practising on today, using scraps from other people's work, since I wasn't making a real capsule, yet. The technique involves using a pair of pliers to first crimp the end of the tube of metal shut, one third at a time, such that the three crimped bits meet in the middle. Then one carefully trims the edges of the three crimped bits so that both sides of the metal are not only in contact, but at the same height. Then one takes a bit of sharpened graphite, which has been inserted into a rod attached by wires to a large box that controls the voltage (after first checking to see that the voltage has been set to an appropriate level, whcih, for the gold capsules of this size is just over 30 volts). One then carefully (while wearing protective glasses) pushes the button on the rod and moves the point of the graphite along the three lines at the top of the capsule. When done correctly the gold melts and the end of the capsule is fused shut with no air holes remaining. When done incorrectly the metal goes past molten to ugly and scared. If one happens to pick up one of the smaller diameter (1 mm?) platinum tubes instead it will take more hand-strength to crimp the edges, and 30 volts will be way too much energy to use, as I discovered when the metal melted the entire end and left a hole in the tube itself. But these things happen when one is left alone to practice and find things out for oneself...