15

One of the key considerations is that much of the interesting mechanical behaviour doesn't occur within the bulk of the material - it occurs at the interfaces between crystals (known as grains). Grain boundary slip, rotation and growth often defines the mechanics - carbon has a tendency to block the motion of grain boundaries, which are one of the key ...


14

First, the alloy $(0.5$ to $\pu{2 g})$ should be treated by $\pu{10 mL}$ nitric acid $32\,\%.$ All metals will get dissolved, except tin and silicon, which will be transformed into insoluble dioxide $\ce{SnO2}$ or $\ce{SiO2}$. Dilute in $\pu{100 mL}$ hot water. $\ce{SiO2 + SnO2}$ will make a gelatinous precipitate, that can be eliminated by filtration. Add $\...


10

You can't find primordial radium because it's half life is too small compared to earths age. Even the radium isotope with the longest half life, $\ce{^{226}Ra}$ has a half life of only 1600 years which is magnitudes smaller than the age of the earth, which is estimated to be around $4.54\times 10^9$ years[1]. This means that whatever radium we can find in ...


9

Let's consider that steel may contain $\pu{1\%}$ carbon. I know it is a bit much. Let us express this mass concentration as molar concentration for a sample of $\pu{100 g}$ of steel. Since this sample contains $\pu{99 g}$ of iron, this amount equates to $$n(\ce{Fe}) = \frac{\pu{99 g}} { \pu{56 g mol^{-1}} } = \pu{1.768 mol}$$ and $$n(\ce{C}) = \frac{\pu{1 g}...


8

The factors that generate mineral concentrations are complex and often only partly known Introduction: geology is complicated The one thing we can be very certain about is is that the distribution of minerals in the earth's crust has very little to do with the primordial origins of the component elements (that is where they came from in the early solar ...


5

There are a few papers on Zinc-Platinum Systems (e.g., Ref.1 and 2, which are also sited in Ref.3), but most of them are in German. However, there were few useful data published by Johnson and Dillon in their Research and Development Report (Ref.4): $$ \bf{The \ structures \ of \ platinum-zinc \ intermetallic \ phases}\\ \begin{array}{l|l r r} \hline \text{...


5

Elastic deformation properties like stiffness (Young's Modulus) vary very little with alloying element concentration since we are only working on the pre-yield bond strength. A pure iron, a carbon steel and a high alloy steel will only vary by about 15% in stiffness. So elastic properties will, as you suggest, be fairly invariant under small changes in alloy ...


4

It is prevented by shifting the equilibrium $$\ce{MgCl2(s) + H2O(s,g) <=> MgO(s) + 2 HCl(g)}$$ to the left, by removal of $\ce{H2O}$ and providing enough $\ce{HCl}$.


4

The purpose of roasting a/o calcination is oxidation a/o decomposition of original ore to form metal oxides. It is desirable to keep the intermediate product solid to obtain porous product. This allows easy access for further reduction by carbon monoxide by coke or charcoal reduction process. If oxides were in form of a solidified melt, the reduction ...


3

The gangue is mainly made of clay, and clay is a mixture of aluminosilicates which are hydrophilic, because their structure is surrounded by $\ce{-O-H}$ bonds. $\ce{O-H}$ bonds can make hydrogen bond with water, so they are easily wet by waters. If minerals are crystallized and not surrounded by these same bonds, they are hydrophobic. It is the case for ...


2

Let's subdivide the CO2 standard entropy change reversible process into 3 parts: Isothermal expansion of one mole of oxygen from 1 bar to the equilibrium partial pressure of oxygen in a reactor operating at equilibrium at a total pressure of 1 bar (a Van't Hoff equilibrium box) Injection of one mole of oxygen at its equilibrium partial pressure into the ...


2

Your equation is the sum of two different and independent equations, namely $$\ce{2 PbS + 3 O2 -> 2 PbO + 2 SO2}$$ $$\ce{PbS + 2 O2 -> PbSO4}$$ And these equations are no use for producing metallic lead. They are not a moderate oxydation, as the ratio $\ce{O2/PbS = 5/3}$. Producing metallic lead by moderate oxydation requires a reaction based on the ...


2

First of all, let's be clear on the the formula for chalcopyrite. It is $\ce{CuFeS2}$. The other copper-iron sulfide ore is bornite, $\ce{Cu5FeS4}$. Now, let's talk about copper extraction. What is written in your question is not correct and I am quite sure that's not how copper is extracted. If you heat the ore (roast) in reverberatory furnaces, it happens ...


2

Chalcopyrite $(\ce{CuFeS2})$ is the most common copper bearing mineral on earth (Approximately 70% of the world’s copper reserves are contained in the mineral chalcopyrite), but also the most stable minerals because of its structural configuration, face-centered tetragonal lattice (Ref.1). At present, there are basically two main methods employed worldwide ...


2

As we discussed in the previous query Is there any evidence, any evidence at all, that nascent hydrogen actually exists?, the nascent terminology is still in use even in good ACS / RSC journals, which are pretty selective. However, science does not rest on authority; seeing the usage of nascent (gas) does not make it an absolute truth whoever is the author. ...


2

Fresenius' analytical scheme is also one possibility, although it is not as direct. More information can be found in Harvey's Analytical Chemistry 2.1 Libretext. I bring this up to highlight that even though this is a classical technique, it is still mentioned in some analytical textbooks still in active use.


2

Interstitial compounds are typically obtained when elements such as $\ce{H},$ $\ce{B},$ $\ce{C}$ and $\ce{N}$ are located within the interstitial sites of a metallic substructure. Nonetheless, the metallic substructure is not that of the pure metallic element in most cases. For example let's consider $\ce{Nb}.$ We can dissolve some amounts of $\ce{N}$ inside ...


1

Here is an idea based on the concept of a sacrificial anode. Per Wikipedia, to quote: A galvanic anode, or sacrificial anode, is the main component of a galvanic cathodic protection (CP) system used to protect buried or submerged metal structures from corrosion.They are made from a metal alloy with a more "active" voltage (more negative reduction ...


1

Here is something that I read in a hydrometallury text (see Hydrometallurgy in Extraction Processes, Vol I, by C. K. Gupta and T. K. Mukherjee, Page 15) as an aid in dissolving ores based on the science surrounding so-called activity coefficients. It centers on simply increasing the effectiveness of an acid dissolution by actually using the same (or more ...


1

Under sufficiently high pressure ammonium, $\ce{NH4}$, could form a metal. Such a metallic species may be present in the interiors of Uranus and Neptune [1](https://doi.org/10.1093/mnras/114.2.172). Reference 1. M.F.M. Bernal, H.S.W Massey, "Metallic Ammonium", Monthly Notices of the Royal Astronomical Society V114(2) (April 1954), Pages 172–179; ...


1

blacksmith37's answer is quite correct. An article from 2015 (Ref 1) shows the colors developed on stainless steel over a period of 10 minutes at 650ºC in laboratory air. Ref 1. https://www.tandfonline.com/doi/abs/10.1179/0960340914Z.00000000083 This page lists several options, one of which is to download several articles; the one from which the color ...


1

According to the CRC Handbook of Chemistry and Physics, melting point of $\ce{CaF2}$ is $\pu{1418 ^\circ C}$, of $\ce{Al2O3}$ (in its corundum form) is $\pu{2053 ^\circ C}$, and of $\ce{Na3AlF6}$ is $\pu{1009 ^\circ C}$ (lowest of the all three). Thus the cryolite should melt first. I have read mentions of the problem you asked in the book Nonaqueous ...


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