#video on glass-ceramic #materials like Robax and Zerodur for #bootstrapping optical instruments from household materials, measuring their CTE with a homemade length measuring rig and an infrared thermometer. Also mentions “Photoform” photolithographable glass. He explains how lithium (and zinc) silicoaluminates have a negative CTE and thus convey a vanishing CTE on the glass-ceramic composite, and how 1-6% of titania or zirconia is included as a nucleation agent. He recommends Bach (ed.)’s book Low Thermal Expansion Glass Ceramics.
#video by #Thoisoi on making metal foam #materials. Very low quality text-to-speech audio (in particular, missing all the quantitative information!) and a significant amount of talking-head filler and stock-footage filler, and he spends a bunch of time talking about misleading relationships between metals’ density and chemical properties. He finally starts making hydrogen-blown aluminum foam at 10'20" after some fake video of typing a Google search by melting calcium into it at supposedly 760° in his furnace, but the crucible and alloy don’t glow, so that must be the wrong temperature. Some footage of reacting calcium granules with water and setting them afire. He adds titanium hydride as a hydrogen source, mixing it into the alloy with a quartz tube as it’s starting to decompose, so that the hydrogen will dissolve in the aluminum.
But that didn’t work, so he tried again without adding any calcium beforehand, then adds the calcium granules once the aluminum was already melted; this time, when he adds the hydride, the aluminum starts to foam immediately, but only foams a little.
On a third trial, he lowered the furnace temperature to 700° (but the aluminum and crucible are still not glowing) and got slightly better foam, but still pretty bad, more like sourdough bread than a sponge.
I suspect the calcium is to reduce the surface tension of the aluminum, because the alloy wets the crucible more, but it doesn’t seem to have worked very well.
He bought some commercial aluminum foam samples, which weighed 0.27g/cc, but didn’t bother to test its material properties quantitatively.
#video on #precision #piezoelectric motors
#video on #Chinese word structure, giving many examples of very logical words, in both Mandarin and Cantonese.
#ElectroBOOM #video on #Switzerland, including Montreux, Lausanne, Vevey, Geneva, and finally Annecy and Lyon in France, with lots of pretty tourism footage
#USA #politics #news of #Trump deportations under the Alien Enemies Act; apparently the deportees are being held incommunicado, and their names have not been released to their families.
#Turkish state TV TRT #video about fairly mild #human-rights abuses by the government of #Israel against an Australian tourist, Anastasia. #politics
#BYD #EV #manufacturing delayed in #Mexico by #politics in #China, “fears of the technology leaking into the #USA” #news
more details on #BYD #EV #manufacturing delay in #Mexico, including background about Brazil and possible Mexican tariffs on Chinese steel and aluminum. #politics #China
#news #video saying #BYD is #manufacturing #EV cars in Thailand and Brazil, and soon in Indonesia and Hungary. #China #politics