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Questions tagged [metallurgy]

Chemical and physical characteristics of metals and alloys.

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20 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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27 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 ...
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1answer
467 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!...
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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. ...
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Reactions Among Copper, Sulfuric Acid, and Nitric Acid Mixture

I'm trying to determine what reactions are occurring between a solution composed of 10 wt% $\ce{HNO3}$, 30 wt% $\ce{H2SO4}$ and the remainder $\ce{H2O}$ and a piece of pure copper metal. The solution'...
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What are the different phases on this duplex stainless steel UNS32205 micrography?

The question is for my technical culture. I don't ask for a validation of the steel quality but I would like to understand better what can be seen on the micrography. The reactive solution used is ...
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32 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 ...
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1answer
47 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-...
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2answers
56 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 ...
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1answer
53 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
26 views

Explain Wood's metal [duplicate]

The four metals in wood's metal alloy have melting points between 230 and 330 degrees Celsius. So how comes that a combination of these metals have a melting point of 68 degrees? Can someone explain ...
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Question regarding thermodynamic principles of metallurgy

According to NCERT (12), India: Why is the reduction of a metal oxide easier if the metal formed is in liquid state at the temperature of reduction? Answer: The entropy is higher if the ...
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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 ...
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1answer
662 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 ...
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1answer
112 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 ...
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28 views

How to calculate the ratio of copper to get complete recovery of silver from copper nitrate solution?

How to calculate the ratio of copper to get complete recovery of silver from copper nitrate solution(which got after I mix impure solid silver+70% nitric acid), and while adding copper powder which ...
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2answers
151 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: ...
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1answer
4k views

Will we ever run out of gold, silver, copper and other important conductors? [closed]

Conductors are very important in technology. How long will these economically viable reserves last? (for commercial use)
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1answer
83 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 ...
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40 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 ...
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1answer
140 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 ...
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0answers
39 views

What is Latinum an alloy of?

I was looking at grad rings from my university and one of the material options is Latinum. Anyone know what this is an alloy of? Any time the term is included in a search, it brings up a bunch of ...
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27 views

What's the difference of the emission characteristics of pyrometallurgy and hydrometallurgy processes

I have learned about that pyrometallurgy and hydrometallurgy processes are two major method to refine the metal ores for industrial applications. For some reason, I want to compare the different ...
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1answer
47 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 ...
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1answer
66 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.
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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 ...
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1answer
161 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?
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1answer
31 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. ...
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1answer
24 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.
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1answer
64 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 ...
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1answer
48 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 ...
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0answers
131 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 ...
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0answers
38 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 $\ce{Cu(I)FeS2}$?
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1answer
630 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. ...
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I tried to dissolve Iron ore into HCl. Some powders stuck on the bottom of the beaker. How do I remove?

So.. I had some Iron ore powders (50g), and I tried to dissolve them into HCl with heat. After 30 mins, I took some powders from the beaker but some remaining powders were stuck on the beaker. From ...
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2answers
206 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 "...
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1answer
159 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 ...
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0answers
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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 ...
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2answers
469 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 ...
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1answer
93 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/...
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1answer
110 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 ...
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0answers
42 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
332 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 ...
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1answer
59 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
69 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
43 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?
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1answer
412 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.
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1answer
41 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 ...
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1answer
359 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?
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1answer
2k 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 ...