Questions tagged [metallurgy]

Chemical and physical characteristics of metals and alloys.

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9
votes
3answers
860 views

Why Isn't the American Nickel magnetic?

I never thought that modern American nickels actually contained nickel anymore. However, according to this site, the coins actually do contain 25% Nickel, the rest being copper. And yet, No US coin ...
1
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0answers
33 views

Importance of concentration of gold in gold parting

I read following lines about gold parting: Gold is not attacked by $\ce{H2SO4}$ or $\ce{HNO3}$, but copper and silver dissolve in them, when concentration of gold is less than $30\%$. If however, ...
1
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1answer
44 views

Use of Spiegeleisen in manufacture of steel

I recently read the following statements related to Manufacture of steel via Bessemer Process: When no more $\ce{CO}$ is produced (i.e. blue flame disappears) a calculated amount of Spiegeleisen (...
0
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1answer
38 views

Could metal hydride storage tanks for hydrogen store helium as well, given their repective atomic radii? [closed]

With atomic radii very similar, could helium dissolve into metallic foam about as well as hydrogen, thus making metal hydrite hydrogen tanks suitable for helium as well?
0
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2answers
64 views

In pig iron, from where does carbon in it comes from?

I've read that: "During extraction of iron another impurity appear which is carbon from coke in furnace." However, I don't understand how there will be enough unreacted carbon that would blend ...
-1
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1answer
26 views

Should I be concerned about a galvanic reaction between silver solder and stainless steel?

I would like to solder a drain fitting onto my ultrasonic cleaner's tank. The fitting and the tank are both stainless steel. During its operation, the tank is filled with a cleaning solution and heat ...
4
votes
2answers
567 views

What does it mean to 'fuse' ores? [closed]

For the extraction of chromium, fusion of chromite ore with sodium or potassium carbonate in excess of air is done. What exactly happens in this 'fusion' process? source : ncert chemistry class 12 ...
-1
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3answers
76 views

What is Rinman's green used for? [closed]

I can't find any info about it's uses neither in book nor in internet. Any help would be appreciated.
2
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3answers
95 views

How can Ellingham diagrams be linked to Gibbs energies of formation?

My textbook quotes the following as the limitation of Ellingham diagram: The interpretation of $\Delta G_\mathrm{f}^\circ$(standard Gibbs free energy of formation) is based on $K$ ($\Delta G_\...
-1
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1answer
20 views

Difference between a species and a phase in a solution? [closed]

Overview: As of my knowledge from metallurgical thermodynamics a phase is a thermodynamically stable and homogeneous entity made up of different species of a given concentration. e.g = 'Austenite' ...
1
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0answers
23 views

Zinc Ink Availability [closed]

does anyone know where I could purchase zinc ink? Sigma Aldrich only sell Zinc Oxide, and I'm struggling to find a method in which I could remove the oxide after I print onto a polymer substrate. ...
1
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0answers
20 views

How does sodium borate (Borax) function to promote Fe-Fe bonding?

Borax is used as "flux" during metal forging to help stick two pieces of steel together. I am curious what is happening at the atomic level. How does the addition of borax promote Fe-Fe bond formation?...
1
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0answers
22 views

How do carbon content and various heat treatment cycles affect the properties of steel at the micro-level?

I watch a YouTube channel by Alec Steele where a lot of metal forging is done. From this I know that varying the carbon content in steel drastically alters the physical properties of the metal, as ...
1
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0answers
21 views

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
votes
1answer
56 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 ...
1
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0answers
21 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
49 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 ...
7
votes
1answer
101 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 ...
0
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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
53 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 ...
-1
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1answer
80 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 ...
0
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1answer
201 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 ...
26
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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?
-1
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1answer
49 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 ...
1
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1answer
97 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
votes
1answer
186 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
votes
0answers
53 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
50 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
votes
1answer
589 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
votes
1answer
127 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
176 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
63 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) / ...
6
votes
1answer
74 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 ...
2
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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
votes
2answers
249 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 ...
0
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0answers
25 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\...
1
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0answers
250 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
votes
1answer
132 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 ...
0
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0answers
391 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
81 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
56 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
vote
1answer
329 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. ...
8
votes
3answers
845 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
vote
1answer
46 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
votes
2answers
426 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 ...
0
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0answers
27 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?
2
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0answers
54 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
votes
4answers
2k 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!...
1
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0answers
61 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. ...