Questions tagged [metallurgy]

Chemical and physical characteristics of metals and alloys.

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30 views

Why is there carbon lining on the steel vessel in Hall Heroults process?

I read This answer, and completely understand that why graphite anode is used , but I have read that the vessel acts as the steel cathode but with lining of carbon. What is the need of this carbon ...
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1answer
42 views

What explains the case hardening color effect?

Year 11 chemistry student here. I'm curious about how the case hardening effect works on metals. I know that when the electrons gain an energy 'level' or lose an energy 'level' they emit light at ...
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What lab equipment did Marie Curie use to isolate radium?

My experience in growing crystals for condensed matter physics has been sealing grams of material in ampoules which get heated in laboratory furnaces, so I don't have the experience to understand how ...
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60 views

How does liquid gallium interact with a gold leaf

I would like to know what happens when gold leaf comes into contact with liquid gallium. Will the gold dissolve into (alloy with) the gallium, wet the gallium or have no reaction with gallium? The ...
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40 views

What is the minimum thickness for stainless steel crucible to melt aluminum

I am planning to make a stainless steel crucible (air-tight) to melt aluminum. Aluminum is known to oxidize in presence of air. I therefore want to create a custom crucible made with sheet metal ...
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1answer
41 views

Home foundry — melting aluminum, mitigating undesirables

I am going to be melting aluminum cylinder head and some soda cans in the home foundry. I am aware the sulphur and the hydrogen present in the melt can make aluminum prone to cracks and brittle. Are ...
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51 views

Is melting aluminium in the presence of carbon dioxide desirable?

So aluminium cans melting is prone to formation of aluminium oxide due to presence of oxgygen and thin sheet of aluminium (large surface area). To mitigate this I can design a cruicible which is ...
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2answers
184 views

Why does an mercury ore exist as HgS?

Cinnabar($\ce{HgS}$) is one of the most common ores of mercury. Why does it not exist at $\ce{HgO}$ or some other such compound? Is there any reason for why it is so prevalent? Does it react less ...
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1answer
34 views

Side product obtained in reduction of cuprous oxide with carbon

So my book sates that in the extraction of cuprous oxide, the following reaction takes place. $$\ce{Cu2O + C -> 2 Cu + CO}$$ This makes sense to me, if it is seen as the following two reactions ...
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Can metal matrix composites be alloyed after their creation?

I've done a little research on metal matrix composites (MMCs), purely for fun and out of interest. Different types of metal powders are combined with reinforcement materials, to produce a reinforced ...
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Why does 'softening' of lead oxidise only elements other than lead?

In a flowchart describing the steps to refine lead obtained after the reduction step, my book1 gives a short note on the process 'Softening of lead' where the crude lead is melted in the presence of ...
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How many kilograms of graphite are consumed while producing 4 kg of Al through Hall-Heroult process?

How many kilograms of graphite are consumed while producing 4 kg of $\ce{Al}$ through Hall-Heroult process? This looks like a simple stoichiometry problem: $$\ce{4Al^3+ + 12e- -> 4Al} \; \; \; \; \...
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How can a minor constituent of an alloy, like carbon in steel have such a profound effect? [closed]

In steel that is 0.65% carbon by weight, barely one in 34 atoms is carbon (assuming no other additives/impurities). How can such an outnumbered constituent make such a big difference? Surely many of ...
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Are platinum metal whiskers very unusual?

Over 20 years ago I pulled my first set of platinum spark plugs out of a car because the engine was missing badly. Two of the six plugs each had one whisker in the gap between electrodes. One crossed ...
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1answer
206 views

Electrolytic Refining of Silver Nitrate

I read that the electrolytic refining of Silver is done using dilute silver nitrate as an electrolyte and a small percentage of free $\ce{HNO3}$. The following reactions are possible at the anode: $$\...
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1answer
64 views

What is the naming convention for Sn and Pb in inter-metallic compounds?

How would one go about naming inter-metallic (specifically, transition post-transition) compounds containing tin and lead? It is usually easy figuring out the naming of such compounds as they follow ...
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2answers
168 views

Why is Na+ reduced instead of H+ in the electrolysis of dilute NaCl(aq) with Mercury cathode?

In a class of electrolysis, my instructor told me that Hg forms Na-Hg in the electrolysis of dilute NaCl aqueous solution. For this reason, sodium cations are reduced in the cathode instead of ...
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191 views

Fumes by Melting Aluminium Soda Cans [closed]

I am planning to melt and cast aluminium from soda cans. I went to quora page that deals with "burning" aluminium can, which can release toxic gases as the cans are coated with plastic inner lining. ...
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1answer
40 views

What makes metals malleable and ductile? [closed]

Two well-known Physical Properties of metals is that they are malleable and dutile I was just wondering about what causes metals to be malleable and/or ductile and non-metals to be brittle? What ...
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29 views

Reactions of Depressants

In the froth flotation process, the concentration of a sulphide ore takes place using $\ce{NaCN/KCN}$ as a depressant. It forms a soluble complex with the impurity sulphide. Taking the particular ...
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Difference between calcination, roasting and pyrolysis

Hie everyone. I have been going through pyrometallurgical processes for recycling lithium-ion batteries and l have been coming across these terms; calcination, pyrolysis and roasting which l need ...
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Why does copper oxidise if it is considered a “noble metal”?

I'm an electrical engineer and not a chemist, so please excuse me if this is obvious. When soft-soldering electronic parts, we’re normally taught to clean copper of oxides (like using flux and so on) ...
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Why isn't the American nickel magnetic?

I never thought that modern American nickels actually contained nickel anymore. However, according to this wiki article, the coins actually do contain 25% nickel, the rest being copper. And yet, no US ...
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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, ...
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1answer
63 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 (...
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39 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?
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71 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 ...
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1answer
28 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 ...
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2answers
674 views

What does it mean to 'fuse' ores and why do we use alkali metals in the process?

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? According to my textbook (class XII ...
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3answers
298 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.
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3answers
142 views

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

My textbook1 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_\...
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1answer
22 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' ...
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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. ...
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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?...
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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 ...
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24 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 ...
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1answer
59 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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23 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 ...
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1answer
51 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 ...
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229 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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22 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 ...
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1answer
57 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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83 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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302 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 iron ...
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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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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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107 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?
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1answer
202 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 ...
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61 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 ...
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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%; ...

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