Questions tagged [metallurgy]

Chemical and physical characteristics of metals and alloys.

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8
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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
296 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
425 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?
-1
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1answer
514 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
101 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
851 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
58 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 ...
0
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2answers
199 views

Is it possible to form an alloy of gold and zinc?

I know you can dissolve gold in mercury, but i do not have access to any. Would it be possible to dissolve it in molten zinc instead mercury.
4
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0answers
78 views

What metal is used to back this mirror?

My father is attempting to remove the mirror from a piece of glass. We stripped the black paint from the back and exposed the shiny surface with acetone. In the past he has been able to remove ...
2
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1answer
504 views

Froth floatation process - Use of stabilizers in froth floatation method

How exactly do the stabilizers affect the process of Froth floatation method? I mean how do they stabilize the froth in the process?
-1
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1answer
45 views

How would ceramic coating inside the reactor affect heat transfer? [closed]

With the ceramic coating, would I be able to get its internal temperature raise upto 520. I would like to get a reactor fabricated for plastic pyrolysis. The temperature would maintained around 520C. ...
-1
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1answer
30 views

Paint removal from metal [closed]

What chemical product works well to strip paint off to reveal bare metal in this instance a small tin (guessing to be aluminium or steel) with as good a finish as possible.
1
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1answer
120 views

How to separate platinum from steel?

I'm currently extracting some platinum from an electrode. One part seems stuck in some way (possibly welded) to a piece of steel. I'm guessing it's steel because it's magnetic. I did a heat test on ...
1
vote
1answer
55 views

What is the reason behind the 2% increase in silver metal composition just after melting the raw silver alloy (55% silver)? [closed]

I determined the silver composition from an alloy obtained from a jeweler to be 55% and wanted to extract silver out of it. However, upon melting around 5 kgs of alloy, the silver composition went up ...
4
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0answers
275 views

Refining Tin (Sn)

I am a Copper Cookware Tinner & have a problem in reusing much of the tin that I end up sweeping off the floor etc. Prob about 5kg over the year & it would be great to save this? Now, my ...
1
vote
0answers
125 views

Copper pyrite representation [closed]

What is the oxidation state of iron in $\ce{CuFeS2}$? And also could you please tell it's proper representation: $\ce{Cu2S.FeS.FeS2}$ or $\ce{Cu(I)FeS2}$?
7
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1answer
3k views

Why is ZnO reduced in this reaction?

Consider the following Ellingham diagram. At 673K, the Gibbs energy value of oxidation of Zn is more negative than the Gibbs energy value of oxidation of C (coke). So, Zn should be oxidised to ZnO. ...
10
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2answers
708 views

Brass Instrument: Dezincification or just scrubbed off?

I do own a brass instrument (a trombone). The lacquer is damaged. I asked how to deal with it here. Now I learned that the brass contains zinc, and there is a corrosion process called "...
2
votes
1answer
353 views

Zinc Sulfate Purification

In the process for electrolysis for zinc, three things must be done: Leaching the ZnO Purifying the ZnSO4 by means of cementation Performing the electrolysis However, step 2, as it is presented by ...
1
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0answers
143 views

How nickel plated copper strip can be welded? What is the optimum thickness of nickel layer?

I have a trouble with (resistance) spot welding of nickel plated copper strip to 18650 battery. I tried to weld 0.1mm, 0.2mm and 0.3mm copper strips with 5 micrometers and 10 micrometers nickel plate ...
13
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3answers
969 views

Ellingham Diagram

My textbook says the following about the Ellingham diagram: Each plot is a straight line except when some change in phase ($\ce{s -> liq}$ or $\ce{liq -> g}$) takes place. The temperature at ...
2
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1answer
159 views

How to differentiate magnetite from metallic iron?

Both metallic iron and magnetite, $\ce{Fe3O4}$, are magnetic. Now, iron is grey in color, whereas hematite is black, so that they can be distinguished visually. Now, I have a powdery mixture of iron/...
4
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1answer
202 views

Does carbon monoxide form or carbon dioxide forms when carbon reduces metal oxide?

I would like to discuss this in context of ellingham diagrams. When $\ce{C -> CO}$ line is below metal oxide line, CO is produced. Similarly, in other case $\ce{CO2}$ is produced. But when both ...
1
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1answer
59 views

Iron-platinum refining

If I have an iron-platinum alloy, can I put this into a solution of $\ce{HCl}$ to dissolve the iron, leaving a $\ce{Pt}$ precipitate? I know that Fe dissolves in $\ce{HCl}$ to form $\ce{FeCl2}$ and $\...
2
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1answer
535 views

What does negative current reading in galvanic couple mean?

I used a multimeter in a galvanic testing between two metals. I connect one to metal A and the another end to metal B. Then I immersed the 2 metals in a salt solution, securing that they are apart in ...
4
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1answer
77 views

What is the shiny structure under a metal coating?

I performed a hot dip aluminizing on steel for 15 seconds. Then, after I bent the steel to remove the coating easier, the steel under was rough, shiny, and metallic, and was different from the ...
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1answer
87 views

Which corrodes faster at 5% NaCl solution at room temperature: Steel or Aluminum? [closed]

Which corrodes faster at 5% NaCl solution at room temperature: Steel or Aluminum? Is it true that Al has high corrosion resistance? Or is it just a myth as stated in this article.
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1answer
49 views

What can be a metal cleanser for aluminum?

I want to remove corrosion products in aluminum, but I don't have supply of nitric acid, as suggested by an ASTM method. Which can be a good substitute?
3
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1answer
810 views

Aluminum to prevent Iron corrosion

I have heard of how zinc is used to prevent corrosion of iron. So why not use aluminium coat instead? After all Aluminum oxide forms a stable coat over the surface.
1
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1answer
82 views

Is it possible to have negative corrorion rate and weight loss, meaning specimen [steel] gained weight after immersion in electroyte solution?

Regarding this article, I have read that the corrosion rate and weight loss of a steel specimen after immersion in different corrosive media is negative. I'm surprised that this is really possible. Is ...
1
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1answer
505 views

What is “Woods Metal”

I have a piece of what I have been told is "Woods Metal" it melts at 168F. I am "curious" about how they make it, how low can the melting temperature be?
5
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2answers
4k views

Does cold bluing steel prevent rust?

I've recently purchased a Damascus knife and am patiently awaiting it's arrival in the mail. I have been researching the potential care and maintenance habits for this craftsman blade, hoping to keep ...
2
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0answers
308 views

Reforging tungsten/tungsten carbide temperatures

I was wondering about the reforging of tungsten and the temperature needed. As I understand it, tungsten melts at $\pu{3442 ^\circ C}$ and tungsten carbide at $\pu{2870 ^\circ C}$. However, once a ...
5
votes
3answers
636 views

Can one turn a nickel blue?

I've heard of artificial coin toning, but haven't been able to find a recipe for creating a blue (or blue-ish) nickel coin. While not a metallurgist, I work with one. She tried nitric acid, which ...
15
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5answers
5k views

How do manufacturer remove oxygen from metal during melting?

How do manufacturers remove oxygen from metal during melting? I melt aluminium with nichrome wires and during melting it, it forms lots of slag (aluminium oxide) and I have to remove it manually.
0
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1answer
194 views

How do metal's density affects the corrosion rate?

Based on different formula that can be used to compute the corrosion rate of metals, all of them involves weight loss, time, surface area, and density. I thought that the weight loss, surface are, and ...
0
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1answer
21 views

Can I obtain a different density of a recycled elemental material?

I am recycling Aluminum products/scrap. I melted it and then form cylindrical ingots. When I measure their density, I calculated $\pu{2.4 g/cm^3}$ but Al has density of $2.7$. I think all the ...
21
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4answers
20k views

Why does mercury decolourise a gold ring?

I saw that a gold ring decolourised as it got in contact with mercury . Why does this happen ? Is there any way to reverse this?
0
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2answers
2k views

How do foundries prevent zinc from boiling away when alloyed with Aluminum?

How do foundries prevent lower boiling point metals such as zinc from boiling away when alloyed in a furnace with higher boiling point metals such as aluminum?
0
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1answer
77 views

What research methods can I use in identifying Aluminum in a solid sample?

I do have a cube of solid aluminum. But I need to verify that it is really Al to validate my research. What simple scientific techniques do you recommend?
3
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1answer
42 views

Can I anodize an aluminum coating on steel to have better corrosion inhibition for the steel?

I am planning to coat aluminum on steel and I want to give the steel its maximum corrosion protection. Is anodizing the coating necessary?
5
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1answer
99 views

Why don't alloys self-galvanically corrode?

Total chemistry newbie here (so this may be a fairly obvious question). With that said, I've had a niggling question that I can't quite resolve myself; Given that galvanic corrosion is driven by the ...
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1answer
89 views

Are there non-brittle silicon-based alloys? [closed]

Requirements: Silicon part is greater than 50% Has plasticity comparable to iron.
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0answers
247 views

Why does zinc turn dark?

So I casted a zinc ingot around a week ago and I also casted 2 zinc ingots yesterday. After observing the two side by side I noticed that the older zinc ingot was darker colored, then I went and ...
0
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1answer
210 views

Goldschmidt alumino-thermic process

I recently came across this question in a book. Among the metals $\ce{Cr}$, $\ce{Fe}$, $\ce{Mn}$, $\ce{Ti}$, $\ce{Ba}$ and $\ce{Mg}$, the one that cannot be obtained by reduction of its metal ...
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0answers
941 views

Why isn't mercury electrode used to produce commercial element sodium?

I know that while electrolysing a solution of brine, if we use mercury cathode, we get sodium amalgam instead of having hydrogen gas liberated. Even the Castner-Kellner process uses this to produce ...
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1answer
229 views

Why are there two vertical axes in the iron-carbon diagram? [closed]

More precisely, why do we have two axes that represent the same parameter, which is temperature?
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0answers
159 views

Very fast brass oxidation

I work for a company that manufactures pyrotechnics for the oil and gas industry, and we have been having an odd phenomenon occur. One part, a brass tube with a copper clip filled with black powder, ...
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3answers
1k views

how to separate aluminum from aluminum alloy

In an attempt to produce aluminum oxide ($\ce{Al2O3}$) also known by alumina I try it out to dissolve two old hard drive frame in brine solution one as the cathode and the second as anode, in the ...