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火星上的铁陨石为什么不生锈或氧化?为什么他们的?

维基百科是维基百科的2005篇文章火星探测器的Basketball-Shaped发现激起争议说:

陨石的表面被发现明显的腐蚀。研究人员还不能确定这是否意味着它到达最近彻底或它可能是沙石。

在地球上我们通常不会看到干净、闪亮的铁表面,因为铁很容易在短时间内氧化甚至在室温下由几个氧化空气的组成部分。这些存在火星上当然在浓度低得多,但也有其他氧化剂包括高氯酸盐。然而铁陨石在火星上发现我知道的隔热板岩和蛋的岩石)看上去干净做其他人所示,《天空和望远镜》的文章。

知道为什么吗?最近他们降落,氧化没有多大变化,还是他们喷砂清洁作为凯伦·斯蒂尔的字符夏娃McHuron告诉柯克其中一个矿工与肮脏的铸铁煎锅^__在第十二行星storm-plagued参宿七。

这两个陨石被好奇心的照片中可以看到

这个答案来叫什么名字的流星体撞击月球,火星,或者几乎任何不是地球?
这个答案来谁发现了“蛋摇滚”?好奇号还是人?

也看到好奇心在火星上发现铁陨石

^__从这个答案

回答

* * tl; * *博士:与地球相比,火星大气中很薄;此外,它还含有更少的氧气和水(即。,很干)。冷得多。这些条件可能减缓氧化率无关。纯铁的一个对象,注意根据英文维基百科(火星)[1]:>“火星的大气层由约96%的二氧化碳、1.93% >氩和1.89%氮气与氧气和水的痕迹。”This contributes as _plausible contribution_ for a lesser rate of oxidation than on earth because the concentration of an oxidizer (i.e., oxygen) is much lower (0.146 vol%, according to the side table, _ibid._) if one assumes absence of processes splitting the $\ce{CO2}$ to yield oxygen. To set these values into context (entry [Earth][2]): > "A dry atmosphere is composed of 78.084% nitrogen, 20.946% oxygen, > 0.934% argon, and trace amounts of carbon dioxide and other gaseous molecules. [...] Water vapor content varies between 0.01% and 4% but averages about 1%." Equally note that the reported surface temperatures on Mars (min 130 K, mean 210 K, max 308 K) are substantially lower, than on Earth (min 184 K, mean 287.16 K, max 330 K) -- _equally_ slowing oxidation. About water and atmosphere humidity: Provided the meteorites get water wetted, said perchlorates could start to work as oxidizer of iron. In comparison to this, _dry_ perchlorate will remain inactive. Again, Mars' atmosphere (0.0210 vol% of water vapour, _ibid._) seems to be considerably more conservative than Earth's. You can't have oxidation alone, it is a electrochemical process where some other material in contact with the one oxidized has to be reduced. Corrosion of the meteorites equally could occur if these simultaneously contain grains of metals / alloys differing in the their [electrode potential][3] provided - these grains were in close contact with each other, especially if their grain boundary were water wetted, _and_ - if one of the metals / alloys -- relatively speaking -- would be «less noble», i.e. a material with a more negative reduction potential, than any other grain / material in contact. The less noble grain than would become a [galvanic anode][4] and eventually be "eaten away", protecting the other, more noble one, to be oxidized.([table][5]) The formation of these little, local [electrochemical cells][7] could be even more important if there were _salty water_ droplets on the surface at room temperature and above accelerating corrosion. (This, by the way, a reason why steel bridges and copper house roofs exposed to the climate and atmosphere of salty seas are more prone to [galvanic corrosion][8] than similar constructions only exposed to fresh water.) Presence of phosphates in said meteorites however could slow down the oxidation of the meteorites ([passivation][9], as assumed for the [Iron pillar in Dehli][10]). _Note:_ The initial answer assumed iron meteorites to contain discrete grains, occasionally altogether with grains of other metals. A comment by`@KenFabian` pointed out [iron meteorites][11] however mainly consist of (Fe,Ni) _alloys_. Their electrochemical properties may be different to their components (e.g, [table][6]), which the edit aims to include. [1]: https://en.wikipedia.org/wiki/Mars#Atmosphere [2]: https://en.wikipedia.org/wiki/Earth#Atmosphere [3]: https://en.wikipedia.org/wiki/Standard_electrode_potential [4]: https://en.wikipedia.org/wiki/Galvanic_anode [5]: http://hyperphysics.phy-astr.gsu.edu/hbase/Tables/electpot.html [6]: https://web.archive.org/web/20150516030826/http://www.corrosionist.com/Galvanic_Series_of_Metal_in_Seawater.htm [7]: https://en.wikipedia.org/wiki/Electrochemical_cell [8]: https://en.wikipedia.org/wiki/Galvanic_corrosion [9]: https://en.wikipedia.org/wiki/Passivation_(chemistry) [10]: https://en.wikipedia.org/wiki/Iron_pillar_of_Delhi [11]: https://en.wikipedia.org/wiki/Iron_meteorite

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1

\ begingroup美元这几乎总结。很少有火星大气中的氧气。无论“微量氧”是在大气中,在一个更低的总压,所以氧气的分压是微不足道的。 \ endgroup美元
- - - - - -Gimelist
2020年3月26日,44
\ begingroup美元请注意,作为纯铁金属陨石没有被发现;他们都是铁镍合金——主要是taenite或kamecite。 \ endgroup美元
- - - - - -肯费边
3月26日,2020年在第五章39节
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\ begingroup美元 @uhoh你第一次报价(维基百科的2005篇文章)允许:a) metorites发现是闪亮的,因为他们是年轻的。b)他们是旧的,但因为他们是沙子被氧化的痕迹是微不足道的(火星尘暴)。c)他们是旧的,但低浓度的氧气和水(维基百科条目的火星大气读起来几乎像一个低压惰性气体)减缓氧化最小速率/没有明显的氧化。源访问我并不意味着如果火星上的影响以来这些meteroites决心排除),b),或c)。 \ endgroup美元
- - - - - -梧桐树下
2020年3月26日,在十一14
2

\ begingroup美元 @uhoh再保险排除一个(a, b, c) /缩小范围的年龄这些metorites:根据meteoritestudies.com/protected_dating.htm迄今为止,它是可能的。原理类似于碳时钟,同位素确定通过质谱分析Sr / Rb比率,技术占主导地位,直到1980年代。也许火星探测器(将)使用这样一个分析器。 \ endgroup美元
- - - - - -梧桐树下
2020年3月26日,29
1

\ begingroup美元 $ \ ce{二氧化碳}$可以减少一氧化碳,通过这样做,铁氧化。但它远远不如氧氧化。但重要的关键是总压强较低。 \ endgroup美元
- - - - - -Stian
2020年3月26日15:08

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