Questions tagged [metallurgy]
Chemical and physical characteristics of metals and alloys.
183
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Tungsten-Rhenium alloy connections to Copper. Methods?
I want to use some fine WRe wire (50 micron diameter, 80/20) in a particular environment where it has to conduct a few millamps of current while supporting 100g of mass. The problem being the contact ...
2
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1answer
51 views
Solubility of Lead in water from leaded pipes in Roman aqueducts
Lead can undergo the following reactions when cold and hard water passes over it:
$$\ce{Pb^2+ + 2Cl- -> PbCl2}$$
$$\ce{Pb^2+ + SO4- -> PbSO4}$$
All these salts are sparingly soluble in water ...
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0answers
18 views
Is fluorinated steel corrosion resistant from normal oxidation?
I've recently learned of a compound named Chlorine trifluoride a powerful fluorinating agent. The common way to store it seems to be in regular steel drums where it flash oxidizes the inside of the ...
1
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1answer
43 views
Historic Importance of Tin(Sn) [closed]
How important is tin for a bronze age society when there's many copper alloys including arsenical bronze. If you're out of tin whats the next best copper alloy(s) for making shortswords and axe blades ...
3
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1answer
41 views
Need of refining aluminium and Hoope vs Hall–Héroult processes
Recently I was taught how aluminium is commercially extracted. The ore is first concentrated by leaching either by Bayer's process for red bauxite (impurity: $\ce{Fe2O3}$) or by Serpeck's process for ...
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0answers
20 views
Separation of Al-Si alloys without electrolysis
Can pure (or roughly pure) $\ce{Al}$ be somehow thermally, chemically, or physically separated from the $\ce{Si}$ contained in an $\ce{Al-Si}$ alloy? How? Approximately what purity of Aluminum can be ...
1
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1answer
48 views
Gallium makes aluminum soft like a wet tissue. Any other metals or alloys that are vulnerable to similar damage? [closed]
Gallium can make aluminum soft and brittle as long as it bypasses the aluminum oxide normally formed on the surface of the aluminum (for example by scratching the surface).
Mercury can weaken ...
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1answer
63 views
What is the physical meaning of the statements like “weight percentage of FeO in Fe”? [closed]
I have always had the notion of calculating weight percentage of Fe in FeO. It always seems that we are to calculate at times the weight percentage of FeO in Fe.Particularly when one weight percentage ...
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1answer
110 views
How do I solve this problem on mass balance from blast furnace iron making?
Question
An ironmaking blast furnace produces hot metal of the composition: $\pu{93.6\%}$ $\ce{Fe},$ $\pu{2.1\%}$ $\ce{Si},$ $\pu{3.6\%}$ $\ce{C},$ $\pu{0.7\%}$ $\ce{Mn}.$ The composition of the ...
25
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4answers
8k views
Is “stainless” a bulk or a surface property of stainless steel?
In particular, if I cut a block of stainless steel in half, would the newly formed faces be stainless as well?
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34 views
However what is so acidic about CaO and basic(no pun intended) about SiO2 while calculating basicity of slag?
I have seen Basicity to be calculated as $\mathrm{B} = wt\%\:\ce{CaO}/wt\%\:\ce{SiO2}$ particularly in slag bascity/acidity calcuations. Now I do not think that $\ce{CaO}$ is the most basic oxide that ...
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1answer
84 views
Why do we use coke instead of coal in order to reduce FeO as basic reaction in ironmaking process?
Why is coke used as a reducing agent to reduce FeO to produce iron instead of coal.I admit that coke is carbonaceous but what is it that compels us to use coke instead of the naturally available coal?
2
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1answer
110 views
Why is a TTT diagram called isothermal transformation diagram?
Why are TTT diagrams called isothermal temperature diagram?As far as I know the temperature variation is plotted with the variation of time in a TTT diagram. Then why do we call it "isothermal".What ...
2
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0answers
51 views
Why will A atoms diffuse from β phase to α phase and B atoms from α phase to β phase?
At the initial compositions 1 and 2 of $α$ and $β$ respectively the chemical potentials of A and B atoms in each phase can be found by extrapolation of the tangents to the free energy curves at 1 and ...
5
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1answer
48 views
Weathering steel
I'm building something out of weathering steel (A606). It is chemically formulated to rust until it becomes chemically stable and stops rusting. Its composition is: Carbon: 0.22%; Manganese: 1.25%; ...
7
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1answer
221 views
Use of cryolite and fluorspar in electrolytic reduction of pure alumina by Hall-Héroult process
Cryolite $\ce{(Na3AlF6)}$ and fluorspar $\ce{(CaF2)}$ are added to alumina to lower the temperature of the mixture from $\pu{2000 °C}$ to about $\pu{900 °C}$ and also to increase the conductance.
But ...
8
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1answer
120 views
Activators for non-sulphide compounds in froth floatation
I was recently studying about Metallurgy.
Concise Inorganic Chemistry by J. D. Lee claims the process of froth floatation can also be applied to non-sulfide ores such as Malachite ($\ce{CuCO3.Cu(OH)...
2
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1answer
108 views
does aluminum oxide float on molten aluminum and by what mechanism?
Not really a chemistry question since no reactions happening, but couldn't find a more appropriate stack exchange site.
Considering recycling aluminum cans for scrap metal using induction heating. I'...
0
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1answer
39 views
Why does roasting requires lower temperature than melting point
Why do processes like roasting and calcination require a temperature lower than the melting point? Since intermolecular forces are lower in a liquid won't it be easier to oxidise (roasting) / ...
5
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1answer
58 views
What happens to the carbon in carbon steel when it rusts?
Carbon steel is iron containing some carbon in various forms of iron carbide.
When it rusts (oxidises), the iron becomes part of all kinds of crystalline and amorphous iron oxides and hydroxides, ...
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0answers
37 views
What chemical reaction could be used to make copper pennies a vibrant red?
I’m an artist working on a piece using pennies to illustrate my drawing and I need my pennies to be red in a certain portion. I’m trying not to use paint and was wondering if there was a way to make ...
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0answers
39 views
Are there any surface treatments that would make calcium usable for metallurgy?
Calcium is the best conductor for its weight, but the soluble powdery oxide makes it impractical for use in power lines. Are there any surface treatments or alloying processes that could help?
(...
2
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2answers
244 views
Leaching of copper using zinc
Why can we not use zinc for extracting copper from a solution containing $\ce{Cu^2+}$ ions even though it is a better reducing agent than $\ce{Fe}$?
I am studying metallurgy and I cannot understand ...
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0answers
23 views
Why does the reaction with copper and nitric acid change with concentration? [duplicate]
Depending on the concentration of nitric acid, copper undergoes two distinct reactions. For dilute concentrations of nitric acid, the reaction is
$$3\text{Cu}+8\text{HNO}_3\rightarrow 3\text{Cu(NO}_3\...
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0answers
178 views
Brass - is this corrosion or oxidation and why did it happen?
I have bought a new brass Y-split water valve which is plain brass but inside is a more polished one, it was packed nicely and I opened it 2 days ago, washed it off with water for some reason, then ...
3
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1answer
121 views
What exactly is the parasitic white layer that forms after iron parts are treated with ammonia? [closed]
I have little to do with chemistry and my only background is the inorganic chemistry I learned at school when I was 13-14 years old.
I need to have a basic understanding of the nitrating process (for ...
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0answers
278 views
Eutectic Phase Diagram of Al-Si Analysis
Hello,
How can I know from this phase diagram:
1. The composition of the alloy Al-Si that allows precipitation to occure?
2. The range of temperatures where the Al-Si is soluble?
3. The range of ...
1
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1answer
56 views
Can gold cause tin or other metals to corrode?
I stumbled upon the following article while trying to identify some old RAM modules:
https://www.techrepublic.com/article/quickly-identify-ram-chips-with-these-tips/
In the article, it mentions the ...
1
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1answer
51 views
Substitute molten salt bath with temperature range from 400–500 °C
I'm looking for a suitable substitute for a $\ce{NaNO2/KNO3}$ salt bath (for quite obvious reasons due to the other applications of the latter chemical). The salt mixture needs to have around 400 to ...
1
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1answer
193 views
Should I plate cast iron with copper first before nickel plating?
I have some antique handplane lever caps I would like to retore back to their former glory. They are made of nickel plated cast iron. The plating pin holed and flaked in areas, creating rust spots.
...
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3answers
778 views
Are risks (hexavalent chromium) during Chrome plating temporary, or remain with the product?
Since some chrome plating production processes generate hexavalent_chromium compounds, which are reportedly highly toxic/carcinogenic, I wonder:
Do the hexavalent chromium substances only occur (...
1
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1answer
35 views
How is traditional thermite powder stored such that it doesn’t corrode?
I watched some guy talk about redox reactions. Then he was going to do the good old thermite demonstration. He just had a bottle of thermite mixture. I’m wondering, why didn’t it have a chance to ...
4
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2answers
302 views
Different formulas for copper pyrites and bauxite
In my book in the chapter on General Principles and Processes of Isolation of Elements, I found that the formula for copper pyrites was stated as $\ce{Cu2S.Fe2S3}$ at one place, $\ce{CuFeS2}$ at ...
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0answers
26 views
What are Technetium's physical stress characteristics?
I've looked at periodic and data tables from several sources, but none give mechanical / engineering property data on Technetium. Why is this?
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0answers
47 views
Can hexavalent chromium be created by exposure of chromium alloys to air at room temperature?
I believe that Cr on its own (as in chrome coating) oxidizes as Cr(III) when exposed to air, and similarly I think that it is the same for Cr as a component of stainless steel.
Is it always the case ...
7
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4answers
1k views
What is the black slag formed when sterling silver is melted with borax?
What is the black graphite looking slag that is formed when sterling silver is melted with borax? Is there a way to remove it from the surface of the sterling silver? It appears to be indestructible!...
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0answers
53 views
Is awaruite to nickel sulfate possible?
Much time has passed since my basic chemistry and I am trying to determine if an awaruite mine proposed by FPX Nickel Corp ("FPX") might serve as feed-stock to nickel sulfate for battery production.
...
0
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1answer
58 views
Lead's affinity for oxygen in the cupellation refining process
My inorganic textbook says
Cupellation is a process, where crude gold is taken in a small bowl called cupell and melted in the presence of air. Due to high oxygen affinity of Pb, it is converted to ...
1
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1answer
71 views
How can I make an alloy wetter?
I'm trying to make a Bismuth-Indium based low-melt alloy wetter (specifically, better at wetting to solid metals and glass). I've tried adding gallium, which obviously works, but due to its metal-...
1
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2answers
198 views
How does Nickel harden steel?
Nickel :
Does not harden austenitic stainless steel
Ease the tempering of martensitic stainless steel
Harden maraging steel by forming precipitates
I also read people saying that it harden ferritic ...
0
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1answer
164 views
Effect of oxidation aluminium reflectivity
Aluminium is a fairly good reflector, but oxidation will reduce it's optical reflective properties.
Aluminium is used for reflectors either being deposited on a substrate, or polished and protected ...
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0answers
385 views
Find alloy composition by density
I have a square piece of metal from a processor heat sink that looks a lot like copper. I'm trying to find the alloy composition but I'm not sure how.
I happen to have both a digital caliper and a ...
7
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1answer
3k views
Why is the ore generally converted to an oxide and then reduced? [closed]
In the elementary extraction of metals from their concentrated ores, why is the ore generally converted to an oxide, and then reduced? Why is the reduction of these metal oxides easier than the other ...
4
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1answer
253 views
Which karat gold is harder, 24 kt or 18 kt?
$\pu{24 kt}$ gold indicates that $24/24$ part of it, i.e. $100\%$ of it is gold. $\pu{18 kt}$ indicates that $18/24$ part of it is gold. As gold is a soft element, I reckoned that $\pu{18 kt}$ gold ...
4
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2answers
367 views
Forging steel inside a zero oxygen environment
Intro: I have watched one too many blacksmithing videos and now I have a question: is it possible to forge steel (either just reshape or "forge-weld") inside a no-oxygen environment?
Scenario: ...
8
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1answer
6k views
Will we ever run out of gold, silver, copper and other important conductors? [closed]
Conductors are very important in technology. At the current rate of extraction how long until the world's reserves of copper are depleted?
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1answer
429 views
Extraction of metals using electrolysis
I came across a question that goes as:
The electrolytic method of reduction is employed for the preparation of metals that are:
Less electropositive
Moderately electropositive
Highly ...
8
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0answers
95 views
What is required to achieve 999.9999 or finer gold?
After doing some research on gold purity, I found that the current record of gold fineness is at an astounding 999.999 fine achieved by the Perth Mint, Australia 1957. However, I could not find any ...
0
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1answer
703 views
How can we separate a mixture of two sulphide ores using froth floatation method? [closed]
As we know froth floatation method makes use of the wetting properties of mineral particles.
Mineral particles (sulphide) become wet with oils, while gangue particles get wet by water
According to ...
0
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1answer
57 views
Thermal oxidation of gold(I) sulfide
As far as I know the chemistry of $\ce{Ag}$ and $\ce{Au}$ are almost the same; because $\ce{Ag}$ belongs to the 4d series and $\ce{Au}$ belongs to the 5d series, we know the size of 4d and 5d are ...
