3 ms·

> this looks like trading one problem for another. Every choice trades one problem for another. At a minimum, the new problem is the cost in resources - time,

by mmooss 1y ago

> this looks like trading one problem for another. Every choice trades one problem for another. At a minimum, the new problem is the cost in resources - time, money, personal energy (and in business, usually reputation risk and political capital) - but usually the cost is much more than that, especially when looking at alternative technical solutions. In advice to clients I always present the options as the minimum trade-off (it's my job to minimize it). More generally, the question is, which scenario of outcomes do you want? It could be the scenario with 1% yttrium is far better than the one with oxygen, or that the ytrrium scenario has a very different set of costs and benefits which make it valuable for certain needs that the oxygen scenario doesn't fulfill. It could be that methods for removing yttrium are already mature and only need to be applied to this case. But especially in this case, the report is about research & development. If there were no more problems to solve then it wouldn't be R&D. It's really self-defeating to criticize progress in R&D because some problems remain. 'We scored a goal, but that's just trading one problem for another - the other team has the ball!'

Aurornis 1y ago
> Every choice trades one problem for another. The problem in this case is that the headline claimed “ultra pure titanium” and the closing paragraph had a tiny oh-by-the-way mention that the process contaminates the titanium with yttrium. Which is to say, makes it anything but ultra pure. :) > It could be that methods for removing yttrium are already mature and only need to be applied to this case. Sorry but no. That’s specially a problem they highlighted as needing a solution.
- gsf_emergency 1y ago
  I was more terrified by the yttrium fluoride. That rings a pancreatic cancer bell very loudly. Additionally, you can be sure that people who understand much more chemistry than biology (or who might have accepted their own deaths) are going to make... different tradeoffs That said, I welcome others to look into substituting, eg, aluminum for yttrium in these methods (since titalum is already a thing)
  - adrian_b 1y ago
    Aluminum would not be a substitute for yttrium. Aluminum can be used to deoxidize less reactive metals, like iron. For a metal like titanium, you need a metal that is much more reactive than it. Yttrium is more reactive than magnesium, though less reactive than calcium, which is why it has been chosen. Moreover, aluminum is undesirable in titanium implants, even if many surgeons without scruples have used cheaper Ti-Al-V alloys taken from aviation suppliers, instead of more expensive alloys designed specifically for compatibility with living tissues, despite the fact that it was always pretty clear that such Ti-Al-V alloys are not suitable for long-term implants. Yttrium is also not desirable for implants, so the titanium produced by this method is not good for implants, but it is good for most other applications of titanium, where yttrium is not harmful.
    - mmooss 1y ago
      Where would yttrium be harmful, if you happen to know?
      - adrian_b 1y ago
        It is likely that most of the titanium deoxidized with yttrium would not be used as such, but it would be used for producing titanium alloys. For each kind of titanium alloy, depending on its chemical composition and on its intended crystal structure, yttrium may happen to be harmful or beneficial. Yttrium atoms are significantly bigger than titanium atoms. This can influence the crystal structure and the mechanical properties of the alloys, even with only a small percentage of residual yttrium. Almost pure non-alloyed titanium (which normally contains residual quantities of oxygen and iron) is used in applications where chemical resistance is more important than mechanical resistance, e.g. for medical implants, vessels and pipes exposed to various chemicals, spoons, metal parts that will be in contact with a human body, e.g. rings or bracelets etc. Yttrium may diminish somewhat the chemical resistance of titanium for such applications, but the resistance might still be adequate for many of these applications.
    - gsf_emergency 1y ago
      Delving into the paper: Al has defo been used for deoxidizing Ti but they claim it's "inadequate" The stability of al oxyhalide with respect to al oxide and al halide is the key here? Not sure if that has been "adequately" explored either, especially in experiment (For the sake of more collaborative conversations on HN, not just dissfests :)
- mmooss 1y ago
  > Sorry but no. That’s specially a problem they highlighted as needing a solution. Do you know anything about it? As far as the article goes, they just said it will be ready for production when the problem is solved, not how hard it is.

by mmooss 1y ago

Aurornis 1y ago

> Every choice trades one problem for another. The problem in this case is that the headline claimed “ultra pure titanium” and the closing paragraph had a tiny oh-by-the-way mention that the process contaminates the titanium with yttrium. Which is to say, makes it anything but ultra pure. :) > It could be that methods for removing yttrium are already mature and only need to be applied to this case. Sorry but no. That’s specially a problem they highlighted as needing a solution.

gsf_emergency 1y ago
I was more terrified by the yttrium fluoride. That rings a pancreatic cancer bell very loudly. Additionally, you can be sure that people who understand much more chemistry than biology (or who might have accepted their own deaths) are going to make... different tradeoffs That said, I welcome others to look into substituting, eg, aluminum for yttrium in these methods (since titalum is already a thing)
- adrian_b 1y ago
  Aluminum would not be a substitute for yttrium. Aluminum can be used to deoxidize less reactive metals, like iron. For a metal like titanium, you need a metal that is much more reactive than it. Yttrium is more reactive than magnesium, though less reactive than calcium, which is why it has been chosen. Moreover, aluminum is undesirable in titanium implants, even if many surgeons without scruples have used cheaper Ti-Al-V alloys taken from aviation suppliers, instead of more expensive alloys designed specifically for compatibility with living tissues, despite the fact that it was always pretty clear that such Ti-Al-V alloys are not suitable for long-term implants. Yttrium is also not desirable for implants, so the titanium produced by this method is not good for implants, but it is good for most other applications of titanium, where yttrium is not harmful.
  - mmooss 1y ago
    Where would yttrium be harmful, if you happen to know?
    - adrian_b 1y ago
      It is likely that most of the titanium deoxidized with yttrium would not be used as such, but it would be used for producing titanium alloys. For each kind of titanium alloy, depending on its chemical composition and on its intended crystal structure, yttrium may happen to be harmful or beneficial. Yttrium atoms are significantly bigger than titanium atoms. This can influence the crystal structure and the mechanical properties of the alloys, even with only a small percentage of residual yttrium. Almost pure non-alloyed titanium (which normally contains residual quantities of oxygen and iron) is used in applications where chemical resistance is more important than mechanical resistance, e.g. for medical implants, vessels and pipes exposed to various chemicals, spoons, metal parts that will be in contact with a human body, e.g. rings or bracelets etc. Yttrium may diminish somewhat the chemical resistance of titanium for such applications, but the resistance might still be adequate for many of these applications.
  - gsf_emergency 1y ago
    Delving into the paper: Al has defo been used for deoxidizing Ti but they claim it's "inadequate" The stability of al oxyhalide with respect to al oxide and al halide is the key here? Not sure if that has been "adequately" explored either, especially in experiment (For the sake of more collaborative conversations on HN, not just dissfests :)
mmooss 1y ago
> Sorry but no. That’s specially a problem they highlighted as needing a solution. Do you know anything about it? As far as the article goes, they just said it will be ready for production when the problem is solved, not how hard it is.