Wednesday, 28 October 2009

Background learning has meant a reduction in posting

As the weeks slip by in my new job I find that I’ve not been making time to post. I do have a couple of draft posts which are waiting for photos to illustrate them, but they’ve been in a holding state for ages. Somehow the daily press of learning new skills, applying them, attending language lessons 6 hours a week, and doing the homework, combined with a half-hearted attempt to develop a social life in my new country has conspired me to feel as though I can’t spare the time for posting here. However, my log of manner in which I am spending my hours indicates that I have been making plenty of time for personal e-mail and reading the blogs I follow. In theory some of that time could have been spent writing instead of reading.

Ah, writing; it is such an easy way to communicate with people—simply enter the words into a keyboard at a time of your own choosing, and your audience will have the option to read it later, at a time of their choosing. No need to arrange a face-to-face meeting with them to share your information. No need to repeat yourself over and over—one typing session can communicate to hundreds of people, should you wish it to (and, at times, even if you don’t so wish, so it is always best to be careful what you commit to the written form, lest your words be shared in a venue unexpected).

So, what science have I been doing while I was busy not writing (or, in a couple of cases, not taking the photos to accompany the writing)? So far it has been simply learning the mechanics of setting up my experiments. #1 has been run, #2 is in progress, and #3 is approaching ready to go. Next week, I am told, we will look at the results of #1 in the microprobe and see what there is to see. It will be interesting to compare the two samples. My experiments are being run with about 5% H2O and a small piece of graphite sealed into the gold capsules with the powder. When sealing the capsules it is important to do the welding with the capsule bottom surrounded by water to keep it cool so that the welding process doesn’t boil off the water before it is sealed. I failed to do this with the first capsule I filled. Likewise, I am not certain that I actually managed to get the capsule completely welded shut. If there is a small opening in the capsule it is possible for the water to boil out of the capsule early on in the experiment, and so not be available for chemical reactions.

Given the huge difference in texture between the two samples which comprised my first experiments, this may have happened for one of them. Apparently when water is present in the capsules the result is an amount of porosity in between the grains of powder, despite the high pressure of the experiment, so the end product is soft and easily torn out of the capsule after the run, if one isn’t very careful in the polishing process. However, when water isn’t present the grains of powder are pushed more closely together, and the new minerals have a chance to interlock as they grow, resulting in a much more coherent sample. One of my two samples polished up without a tendency for powder to be plucked out of it, so it is likely that this one operated under “dry” or nearly dry conditions. The other required much more care as it was soft. It was necessary to coat it with additional epoxy before the final polish to keep it from being lost. It will be interesting to compare the results of the two samples. Are there any hydrous minerals at all in the one we suspect was “dry”? I will have to wait till early next week to learn the answer to this question.


Silver Fox said...

This process sounds fascinating! Hope the bulk of them turn out well. I imagine the welding gets easier as time goes on?

A Life Long Scholar said...

Well the first step has gotten much easier. It is now a simple task for me to pinch the end of an empty tube into a triple-junction and weld it shut. Alas, sealing the capsule when full is still a challenge, but one I hope will also get easier with time. I suspect the fact that there is so much more time invested in the filling (and careful weighing at each step) that makes it seem so daunting--if I do the empty one wrong, I've lost 30 seconds, but it is 30 minutes or more gone if I mess up the final weld.