Questions tagged [metallurgy]
Chemical and physical characteristics of metals and alloys.
169
questions
5
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1answer
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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%; ...
4
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0answers
61 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 ...
0
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0answers
10 views
Doubts Regarding Activators for Non Sulphide Compounds in Froth Floating Method of Concentration of Ore
I was recently going studying about Metallurgy and read in a book namely Concise Inorganic Chemistry by J D Lee that the process of froath floating can also be applied to ores such as Malachite (CuCO3....
2
votes
1answer
46 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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0answers
18 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
votes
1answer
46 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, ...
1
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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
37 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
240 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
22 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
82 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
117 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
65 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
vote
1answer
39 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
vote
1answer
47 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
68 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.
...
6
votes
3answers
710 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
34 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
175 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
24 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
41 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 ...
4
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1answer
769 views
What is the black slag formed when sterling silver is melted with borax? [Edited with images]
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
50 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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0answers
43 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
vote
1answer
61 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
vote
2answers
109 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
votes
1answer
119 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 ...
1
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0answers
195 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 ...
6
votes
1answer
1k 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
votes
1answer
162 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
votes
2answers
275 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: ...
9
votes
1answer
5k 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
236 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 ...
7
votes
0answers
68 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
votes
1answer
356 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
votes
1answer
53 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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1answer
94 views
Is it possible to dissolve gold in 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.
3
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0answers
54 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
votes
1answer
286 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
votes
1answer
38 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
votes
1answer
27 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
vote
1answer
88 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
51 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
votes
0answers
192 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
70 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 $\ce{Cu(I)FeS2}$?
6
votes
1answer
2k 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. ...
9
votes
2answers
338 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
221 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
vote
0answers
114 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
votes
2answers
723 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 ...
