Metallurgical Engineering - Science topic

Ethylene carbonate is solid at room temperature, propylene carbonate is also very polar and certainly not volatile.

Well, my first solution is always to go to the source! To be effective and to stay in business, the manufacturers of those rods must have a pretty good methodology and composition to maintain quality! If you want more academic studies, I'm sure that the industry specs will refer back to them at some point.

Hello Anna Ivanova,

I suggest to study "hot-shortness" topic in steels. This phenomenon is typically caused by segregation of impurity elements at grain boundaries and then forming low-melting point phases (such as iron sulfide in case of low-manganese steels with high sulfur content or copper-rich phases in case of copper-bearing steels).

Thank you so much Mr. Tobias Makuochukwu Onyia for your time and very detailed response to my query.

Thank you Mr. Vinodh Sekar for your detailed reply.

Dear Varun:

Without prior exoerimental data on this particular steel, I would maintain that it is practically impossible to accurately predict the DBTT for any low carbon steel. The DBTT will depend on its composition of course, but also on its microstructure and prior heat treatment. The DBTT, however, is extremely sensitive to any small amounts of impurities, such as S and P. The best low carbon steels, with the lowest DBTT, invariably have very low content of these impurity elements (this is termed "aircraft quality" in many higher strength steels). My advice to you is to experimentally measure the DBTT using such simple tests as Charpy impact tests; relying on any predictions or estimates would be highly questionable.

ROR

Another crucial information may be supplied by the company concerning the type/name of the initiator used in the addition ROP of ethylene oxide. This is important in that end groups usually have their own intrusion in many properties and behaviors. Also you may ask if the PEG 100 has been the subject of further post- polymerization treatment. Best of luck in your work.

Thank you so much Mr. Gideon C. Irogbele for your detailed response.

Hi

Regarding Fe-Mn phase diagram,the vertical line towards left represents Fe with allotropic changes occurring room temperature (alpha)=>(gamma) at 912 deg C=> (delta) at 1400 deg C => melting a 1538 deg C. Similary,towards right Mn have at room temperature (alpha) =>(beta)at 707 deg C =>(gamma) at 1087 deg C =>(delta) at 1138 deg C =>Melting at 1246 deg C. At around 1498 deg C,peritectic reaction occurs L + (delta) => gamma(Fe,Mn) similar to Austinite in Fe-C phase diagram. More or less gamma(Fe,Mn) phase is dominants the phase diagram. Up to 4% Mn, alpha(Fe,Mn) (912 to 400)deg C, from 4 to 30% both alpha(Fe,Mn) and gamma(Fe,Mn) will be stable from (912 to 400)deg C. Peritectiod reaction occurs at 700 deg C changing

gamma(Fe,Mn) +beta(Fe,Mn) => alpha(Fe,Mn). Transformation temperature from beta(Fe,Mn) => alpha(Fe,Mn) roughly occurs around and along 707 deg C.

Regarding Fe-Mo phase diagram,there is lot of temperature differences between Molybdenum (2623) and Iron (1539) there are many peritectic reactions in the phase diagram. gamma(Fe,Mo) is reduced to a loop, as alpha(Fe,Mo) is enlarged as Molybdenum is B.C.C if ferrite stabilizer, while austenite (FCC) is shrunken to loop with the addition of Mo. A peritectic reaction at 1500 deg C, converting L + Sigma => R, A peritectiod reaction converting R + Sigma =>Mu. And Eutectiod reaction at 1200 deg C, converting R => alpha + Mu. Another peritectic reaction at 1611 deg C,converting L + alpha => sigma. At 900 deg C, Mu => lamda, below 900 deg C alpha + Mu => alpha + lamda,in between Mu and alpha + lambda we have

lambda + mu.

Example: Basic principle of phase diagram, intermediate phases(alpha + beta) will be alpha(towards left) and beta(towards right),this applies to any phases either solid or liquid and gases.

thanks & regards,

g.sudhakar

phd(material engineering)

hcu

This is a good paper in this regard.

In addition to the given recommendations , does your school have a Career Services Office? Do they hold virtual or in person job and internship fairs? Attend those!

Hi, If you mind take a look at tables of the following paper (all links and licenses are mentioned):

Agree with Mete Abbot sir

Also see the following link: https://eprints.whiterose.ac.uk/130746/8/APT-D-17-00782-%20deposit.pdf

In maraging steels, due to their higher Ni content, elevates the martensite start (Ms) temperature which promotes the easy transformation of austenite to martensite. The martensite formed in maraging steel is different from the one we observe in plain carbon steels. The martensite formed in plain carbon steel is formed by quenching. This martensite so formed is hard and brittle with a BCT structure. However, in the case of maraging steel, martensite formation occurs even with air cooling. This is due to the lower carbon content and higher Ni concentration. The martensite so formed is soft with a BCC structure.

Dear Muhammad,

the reason for your problem is quite clear: lamination creates obstacles to the removal of the evaporated binder. When PVA evaporates, pressure builds up that ruptures the material.

To begin with, you can try replacing the aqueous solution of PVA with an aqueous solution of methylcellulose, the evaporation of which occurs in a wider temperature range and does not create such a high vapor pressure.

If replacing PVA with methylcellulose does not help, then I see no other solution to the problem other than replacing the water-soluble binder with a water-insoluble binder. The new binder must not evaporate, but must be removed by another mechanism, such as melting or oxidation with atmospheric oxygen.

In ceramics, wax-based binders are often used, the removal of which does not cause an increase in pressure in the material. There is also an old technology in which a solution of rubber in gasoline is used as a binder. Rubber does not evaporate as intensely as PVA and does not generate such high vapor pressure. Of course, the use of paraffins or rubber as binders completely changes and complicates the technology of forming a ceramic tape, but there may simply not be another solution.

You may want to check:

Variations in the height of the specimen in its holder, whether increasing or decreasing, cause XRD peaks to change from their original location.

Important and useful pathways are connected to the XRD Curve:

Scherrer’s equation:

Particle Size = (0.9 x λ)/ (d cosθ)

λ = 1.54060 Å (in the case of CuKa1) so, 0.9 x λ = 1.38654

Θ = 2θ/2 (in the example = 20/2)

d = the full width at half maximum intensity of the peak (in Rad) – you can calculate it using Origin software.

To convert from angle to rad

Rad = (22 x angle) / (7 x 180) = angle x 0.01746

Example: if d = 0.5 angle (θ)

= (22 x 0.5)/ (7x 180) = 0.00873 rad

Dear AA DD,

Best option you have HRSTEM to detect precipitate and analyze it.

Borides M5B3 contains mainly W, Cr and Mo. All of MC carbides are enriched strongly in Hf and Ta, with the concentration relationship between these and other strong carbide formers depending on the precipitate's morphology. The microstructure of a Ni-based superalloy can be systematically investigated by X-ray diffraction, light microscopy, energy-dispersive X-ray spectroscopy, and electron microscopy techniques.

Analysisof γ Precipitates, Carbides and Nano-Boridesin Heat-Treated Ni-Based Superalloy can be done using SEM, STEM-EDX, and HRSTEM.

Please refer this site in detail given below.

Hope this is helpful for you.

Ashish

Hello Khalid,

I have some experience working with aqueous alumina tapes, but instead of PVA and PEG, used an acrylic emulsion that performs both functions (binder and plasticizer).

For this particle size, I sintered tapes with 25 vol% (~52 wt%) at 1550 ºC for 2 h and obtained a relative density higher than 98%.

The solid content will depend on how you performed your slurry optimization (dispersant, binders, etc.). By the correct optimization, you will find the higher solid content and formulation suitable to produce defect-free tapes.

PET film works good as carrier film and should be OK for you to detach the tape. You can use also a silicon-coated PET film that would help you to easily detach the tape. However, in this case, you may need to play with some tricks of the surface stresses between silicon and the ceramic slurry.

follow

There are so many questions that it is difficult to answer at once.

First of all, I'll give you some helpful keywords.

1. In the case of carbon steel other than stainless steel, it is difficult for the FCC phase to exist at room temperature without enough nickel or manganese.

2. Each phases stabilizing elements are studied well for FCC Austenite and BCC Ferrite. Please open the follow.

3. Nitro-carbide often coexists, but in general carbon steel, nitride and carbide exist separately. In this carbon steel, W is a strong carbide-forming element, so it is possible to first form tungsten carbide at high temperatures during solidification. And if Al is present, it is expected that AlN will form, then followed by the formation of chromium carbide. At a lower temperature, iron carbide Fe3C will form with remaining carbon after forming (W, Cr)23C6.

Sulfides may exist as WS2 or FeS, which are formed independently at lower temperatures than tungsten carbide and iron carbide.

4. In the Fe-C Diagram, the volume of the matrix phase and intermetallic compound can be approximately predicted by the lever rule. However, the actual ratio is depended on cooling rate. Because it is not an equilibrium solidification.

5. The cooling rate affects the segregation of elements and phase transformation. Therefore, depending on the cooling conditions after casting, and in severe cases, depending on the shape of the casting, different structures may be obtained. If the casting is high alloyed, has the higher differences.

6. I would like to recommend reviewing two papers. Lei Wang Et al., Prediction of mechanical behavior of ferrite-pearlite steel, J. Iron and Steel Research, 2017 and W.C. Leslie, The Physical Metallurgy of Steels, McGraw-Hill, New York, 1981. See the graph at p.217.

Dear Saed Sadeghpour,

I am facing the same issue. I have the same lattice parameters but not the wyckoff positions of atoms in Ti-1023 and Ti-5553.

Kindly share your findings regarding the unindexed regions and also the wyckoff positions.

Hot rolling is preferable process with heat treatment by annealing and normalizing.

Hello,

You may check the article below;

The study is not directly related with the ladle refractory but they have found that compared to CaF2, the erosion on snorkel refractory of CAS-OB increased with the addition of B2O3 within the same amount.

But the process parameters like the addition sequence in process route, chemical composition of slag, processing temperatures, the physical and chemical stability of refractories on slag line will effect erosion level and also B pick-up ratio. Thus, I think it is better to compare these specific conditions with using computational thermodynamic software; FactSage, ThermoCalc, etc.

I also want to delete particles in DPM model . Load this UDF , I want fluent16.1 to show the particle trajectories. the following error occurs : Error: received a fatal signal (Segmentation fault). Error Object: #f.

Muhammad Waqas Khalid Refer the link https://www.researchgate.net/post/How_to_calculate_the_grain_size_through_SEM_images

The FactSage databases contain at least information about Sr3N2, but in liquid aluminum, the program predicted, that the formation of AlN is more likely compared to the formation of Sr3N2.

I guess oxygen plasma would work. I am also looking for making tungsten hydrophilic. If it has not worked for you, i shall try along with oxygen plasma little bit of argon and let you know the result. I wish to coat Ba and Sr Carbonates on tungsten. I have prepared the solution by mixing the powders with water. Solution seems to be consistent. I am unable to coat this solution on tungsten wire. I heated the wire to more than 2000 degrees by passing current into that, then tried to coat the paste, did not work.

Did you try etching it by HF acid ? I am going to try this. If I get results I shall post it here.

Dear Nurly

Yes. there is. Actually, we can get much information about the microstructure of materials by EBSD data.

the grain orientation, grain boundaries (LAGB and HAGB), local misorientation, grain size, and etc, which have been post-processed by EBSD data, can affect on mechanical properties.

if you have more questions, please feel free to contact me.

I think you can consider also ball milling to mix Pd and Ti as powders, then remelting you can control the alloy ad you prefer,

best regards, Simone

Dear Mohsen,

Prior-austenite grain boundaries are those of the steel when it was austenitized prior to quenching and tempering. If the steel's microstructure is fully martensitic after hardening, or contains some retained austenite or lower bainite, the prior-austenite grain boundaries may be revealed.

Prior austenite grain size(PAGB) is important for understanding the microstructure–property characterization relationships in steels. The PAGB plays an important role in defining the microstructural scale of low-temperature phases and the mechanical properties (e.g., strength, ductility, fracture toughness, etc.) of steels in the final product form. It is recommended that swab etching with a solution of 100 ml saturated aqueous picric acid and 0.5 g sodium dodecyl benzene sulfonate(% can you easily determine equivalent to 0.5%) can worked remarkably well for delineating the PAGBs in this steel.

Refer the site:

Hope content is useful for you.

Ashish

Muhammad Waqas Khalid, It is difficult to find plaster of Paris (PoP) molds in the market for lab-scale experimentation. However, you can make PoP very easily using the dry PoP powders (~0.5-1 USD/kg) upon mixing with water properly & giving shape. Once it is dry, you can use it for casting your slurry. The pores in the PoP mold will draw out the water (or other liquid used for slurry making). So, after casting, you need to dry out the PoP completely before pouring slurry for another casting. You can use it many times (I used each mold at least 100 times, never counted though) until the integrity of the PoP remains ok. Hope this is helpful.

With best regards

MN

I read that after leaching of oxidized zinc concentrates with sulfuric acid, the resulting solution is purified from harmful impurities like iron, copper, cobalt, nickel. And with a weakly acidic medium, pH = 5.2–5.3 iron ions are practically precipitated by the formation of hydroxides.

Dear Kumar,

I am also the chief engineer of CAL line. You should look at the cleaning section. Especially the hot water tank. You have a quality problem because of the alkali-NaOH. Alkali solution goes to the furnace section and NaOH decreases the melting temperature of the alloying elements.

Dear Kavin,

Acid mist control has been a severe problem in copper electrowinning operations around the world. The problem is becoming more relevant under the actual and future scenarios in which the production of copper using this route has increased dramatically in the last years. This in combination with environmental regulations are demanding the industry to explore for a definitive solution. The control of acid mist in Copper Electrowinning tankhouses produces a series of benefits such as: reduced corrosion of the buildings, savings in electrolyte heating needs, improves worker’s confort, etc. An important extension of the benefits introduced by the proper capturing and collection/cleaning of acid mist is the associated mechanization of the operations.

Hope it is helpful to you.

Ashish

Dear Naved,

Couple of interesting topics can be chosen for the cathodic potential research areas.

1. Cost of Impressed Current Cathodic Protection for coastal bridges

2. Selection of Thermal-Sprayed Metal Anodes for Cathodic Protection of Reinforced Concrete Structures

3. experimental and theoretical model validation to estimate the cost to install cathodic protections

4. Development of Cost-Effective Cathodic Protection tool for marine structures environments

Hope it is helpful for you.

Ashish

Hi. In continuous casting, usually no material being wasted and could completely optimize production's cost effectiveness. The bars and slabs created are always solid with no cracks. But in ignot casting as traditional method, longer periods of time need due to the individual step and many cracks were created in products.

I recommend the answer from Ebenezer

for more information I suggest to read the book “Solid State Physics” by S O Pillai

Dear rajoshri,

P=l.bXB= 2.1/2*4.5=4.5 (shortest dislocation parity)

simply tou can calculate half plane. Just simple.

The Burgers vector associated with a dislocation is a measure of the lattice distortion caused by the presence of the line defect. The Burgers vector defined in this way is a unit vector of the lattice if the dislocation is a unit dislocation, and a shorter stable translation vector of the lattice if the dislocation is a partial dislocation.

The displacement distance of the atoms around the dislocation is called Burgers Vector. Generally it is denoted by b. It is perpendicular to the edge-dislocation line and parallel to screw dislocation line. Burgers, is a vector, often denoted as b, that represents the magnitude and direction of the lattice distortion resulting from a dislocation in a crystal lattice. For the determination of the Burgers vector you need to insert the type of an expected dislocation. Then go around the dislocation core (line) adding the same amount of steps (vector). The missing vector component is the shift caused by the dislocation. That's the Burgers vector.

The edge defect can be easily visualized as an extra half-plane of atoms in a lattice. The dislocation is called a line defect because the locus of defective points produced in the lattice by the dislocation lie along a line. This line runs along the top of the extra half-plane. In crystal defect. Line defects, or dislocations, are lines along which whole rows of atoms in a solid are arranged anomalously. The resulting irregularity in spacing is most severe along a line called the line of dislocation. Line defects can weaken or strengthen solids.

High voltage electron microscopy (HVEM) as well as the computer simulation of the electron micrographs can be applied to study the contrast behaviour of mixed dislocations with a large screw component of the Burgers vector under different diffraction conditions in order to check the validity of the method proposed. The analysis of the contrast oscillations along inclined dislocations or the image shift relative to the projection of the dislocation line enables us to determine the ‘dislocation parity’ P = sgn (l × b · B) while the halo contrast can be used to define the orientation of the ‘additional half plane’, which is characterized by the normal e = l × b/|l × b| to the glide plane. The parity and sgn (g · e) analysis enables the unambiguous b vector determination whenever solely one invisibility criterion is applicable. The dislocation parameters in heterostructures are investigated by the above method.

Hope it is helpful to you.

Ashish

Dear Graham,

It is generally a novel class of material. In my opinion, it is not made by an additive manufacturing 3 D printing process. It can be produced by liquid phase and solid state processing methods. The alloy is of specific interest in medical industry.

Most HEAs have been produced using liquid-phase methods include arc melting, induction melting, and Bridgman solidification. Solid-state processing is generally done by mechanical alloying using a high-energy ball mill.

These alloys are currently the focus of significant attention in materials science and engineering because they have potentially desirable properties. HEAs have considerably better strength-to-weight ratios, with a higher degree of fracture resistance, tensile strength, as well as corrosion and oxidation resistance than conventional alloys. Yeh was also the first to coin the term "high-entropy alloy" when he attributed the high configurationally entropy as the mechanism stabilizing the solid solution phase.

High-entropy alloys (HEAs) are alloys that are formed by mixing equal or relatively large proportions of (usually) five or more elements. Prior to the synthesis of these substances, typical metal alloys comprised one or two major components with smaller amounts of other elements. For example, additional elements can be added to iron to improve its properties, thereby creating an iron based alloy, but typically in fairly low proportions, such as the proportions of carbon, manganese, and the like in various steels. Hence, high entropy alloys are a novel class of materials.

Ashish

By adding drops of potassium iodide on cold , Lead will precipitate as the yellow precipitate PbI2, which can be completely separated than other by dissolving in hot water

Please check out

https://www.mdpi.com/2075-163X/9/4/232/pdf-vor

For a valid fracture test, crack should be sharp. If this is not the case, the fracture toughness values will be very high. The is a critical tip radius below which there is no effect of tip radius on the fracture toughness. Please refer Fundamentals of Fracture Mechanics - J.F. Knott.

Practically no carbon is lost during vacuum arc remelting.If lower carbon is desired in your cobalt base super alloy , use virgin metals and controlled amount of low carbon Ferro-chromium to meet the the final requirement.

Interesting... Please share me the final answer...

Dear srikar,

Try with electrochemical and ion etch(chlorine), plasma polishing.

General way it may be helpful for you.Use microfiber cloth, fluoride free toothpaste(take on soft cloth , rub it and wipe on the surface, remove surface layer and dry it,), remove scratches in baking soda, dry gently.

Just try it.

Ashish

In the light of above discussion I can say that Laser Induced breakdown spectroscopy is better technique of elemental spectroscopy for the field application. Lot of new techniques are available and are still being investigated to enhance the sensitivity of LIBS technique. Particularly NELIBS Nanoparticle enhanced laser induced breakdown spectroscopy enhances the sensitivity of LIBS by order of magnitude.

You are right, it is not explicitly explained. This is one of those ideas which is "understood". Let me answer as per my understanding. We can do a thought experiment. Suppose all the power we are putting in is wasted as heat. You can take it as zero efficiency heat engine. The rectangular area then is the total power and it is being converted into heat. Now suppose I am able to get some work out of it then area will decrease and complimentary area will be work done. This work in our case is irreversible microstructural change which you can also understand as increase in the entropy of the system.

Aluminium bars could be converted as machined chips through machining process and then chips can be converted as powder through ball milling process

Sorry I cannot give detection limits, but classical narration states 5% (volume/mass fraction?). But I think this statement makes little sense, exept for that it makse aware of the fact that there is always a detection limit. The real detection limit always depends on the scattering power of your phase, on the level of the background intensity determining usually the scatter of the measured intensity. I remember cases where less than 1 mass % of some precipitation phase was clearly visible with a lab instrument. Let's list some important factors:

1. Scattering power (structure factor per volume) of the phase. A W containing carbide will be easier detectable than a 3d metal carbide.

2. Low symmetry will distribute your intensity on many different reflections. Cementite is much more difficult to detect than a NaCl type carbide.

3. The width of the Carbide reflections. Note that the invariant parameter is the integrated intensity, then, broad reflections are more difficult to detect.

4. And, as already indicated: You have to detect the peaks of the phase under consideration above the level of the background. If the latter is high, it is difficult (think about counting statistics). But this indicates that the detection limit can be improved by improving the peak/background ratio, and that is easiest done by suppressing background.

All this indicates that THERE IS NO GENERAL DETECTION LIMIT. If you want to get a feeling, e.g. in the course of a Rietveld refinement, you can introduce a corresponding phase as additional phase with a phase fraction. Then you can check what is the lowest phase fraction you would be able to see above your experimental background. As indicated in point (3) the width of the carbide's peaks (size, microstrain, faulting) will strongly affect the limit.

As you see, like nearly always, it is not so easy.

Dear Franklin,

À crystal is a single solid made of unique periodically arrangement of atoms that give well define form (cubic, hexagonal, etc.). Such forms are obtained by the formation of a nucleus that slowly grows without constrain. The size of a crystal can vary from mm to meters (see the crystals of Naica). By Pvd you can obtain beautiful crystals with a substrate heated near the melting point of the deposited metal.

A grain is a crystal whose growth has been constrained by others crystals growing in the neighborhood. The frontier between two grains "has" to accommodate the distortions of the two distinguished crystallographic arrangements. Thus the grain boundary is formed of many dislocations. Grain size varies from microns to millimeters. Their size can be determined by metallography.

When a metal is solidified, due to thermal or intrinsic stresses, the grains are elasticaly or plasticaly deformed. Inside a grain, little zones, called domains, are created that are homogeously deformed. Their size is thus smaller than the size of the grain. It can be determined by X Ray diffraction for example.

Hope it will be useful.

Sorry, in my answer I vorgot the C₀ . The correct formula is:

C=C₀ exp-(Q/kT).

C₀ is not temperature dependent and is defined by the local change of entropy if 1 vacancy is formed. C₀ should be taken from experimental literature, since it is not easy to calculate theoretically.

Rajorshi Koyal

Best thing is search for its electronic configuration (and bonding in them)

next thing keep in mind for "ferro, ferri, anti...." requires at least two different lattices of atoms, rest is clear.

Dear Rajorshi

In fracture mechanics, there are many distinct formulas for calculating different parameters such as theoretical cohesive strength, fracture strength, critical crack length, and fracture toughness. In the following, two different formulas will be explained:

a) 𝝈_𝒕𝒉=((𝑬.𝜸_𝒔)/𝒂_𝟎) ^(𝟏/𝟐)

where 𝝈_𝒕𝒉 is the theoretical cohesive strength,𝜸_𝒔 is the surface energy, and 𝒂_𝟎 is the interatomic spacing.

However, the observed fracture strength is always lower than the theoretical cohesive strength. Therefore, eq.(b), “known as Griffith’s theory”, was developed:

b) 𝝈_f=((2𝑬.𝜸_𝒔)/πc)^(𝟏/𝟐)

where 𝝈_f is the fracture strength, and c is half of the crack length. Therefore, if the material contains a crack with length of 2c, then the fracture stress will be equal to 𝝈_f . However, this equation is used for brittle materials. You can use Irwin’s modification if your material is ductile-brittle.

You can use eq.(b) considering that 𝝈_f is the fracture strength of your material and 2c is the critical crack length. However, in linear elastic fracture mechanics, stress intensity factor, known as “fracture toughness” of the material (K1c) is calculated, and the critical crack length is determined regarding the amount of applied stress.

I hope this answer could be useful.\

Best regards

Activation energy for a sintering is a system property, namely: the energy barrier which system must overcome to start sintering process. In the discussed case, obviously, the estimated activation energy is a combination of surface/grain boundaries/volume diffusion activation energies of the mentioned materials system.

On the other hand, densification is a sintering result. So, is sintering parameters permitted to overcome the energetic barrier, a sintering process was initiated and then resulted in a certain final density.

Taken into account the mentioned above, I do not see any contradiction between high activation energy and high sintered density, if sintering process was adjusted and optimized specially to the mentioned materials system.

When you refer to thermal gradients you propably refer to solidification processes. For these the temperature gradients are very important as the interface velocity is usually determined crucialy by the transport of the latent heat. Here, of course, special literature exist, but beyond what is taught in general lectures I cannot help much. Your reference to "metallurgy books" seems that there you looked at the soldification sections.

If you are more interested in solid-solid transformations, usually the thermal gradient is less important, simply becausee the latent heat associated with the transformations is much lower than for solidification (the invariant parameter is actually the transformation entropy, connected with the transformation enthalpy via the equilibrium transformation temperature). In that case there is a huge amount of concepts to describe phase transformation kinetics. Porter Easterling is a good starter (having also solidification sections). Models are of course on very different levels. If you want to find much more, you may refer to Christian.

Existence of ferrite (alpha or gamma) and austenite is independent of carbon content. However, the amount of carbon can control the temperature range of phase stability.

They should be typos.

In an oxygen rich top blowing steelmaking process, dephosphorisation occurs at the interface between slag and metal. The direct removal of P by oxygen into slag doesnt happen as P2O5 is unstable at steelmaking temperature and it will reduce immediately after its formation.

2 [P] +5 [O] = (P2O5) ∆ G° = −740375 + 535.365T J/mol

For example, at temperature > 1382 K, the delG becomes positive and P2O5 decomposes to P and O. How can we make the delG negative at high temperature?

Del G = del G0 + RT ln (aP2O5/aP^2*aO^5)

Decreasing the activity of P2O5 or increasing activity of P and O will help to move the reaction in forward direction. Therefore common practice is to add basic oxide such as CaO (strong basic oxide) to reduce the activity of P2O5 and makes the P2O5 phase stable in the slag phase. As mentioned in previous comment, the dephosphorisation reaction in steelmaking process proceeds via the following reaction:

[P] + 5[O] + 3(O2-) = (PO43-)

As you can see from the above reaction, P in the melt requires a oxidising environment([O]), which is generally provided by FeO in slag ( FeO = Fe+ [O]) and also it requires a basic slag (O2-) supplied by the addition of basic oxide ( CaO= Ca + O2-) to reduce the P2O5 activity in slag.

So to answer your question, a high FeO slag supplies [O] and favours the oxidation of P to P2O5. However, a basic slag is absolutely necessary to make P2O5 stable in the slag phase. Therefore beyond certain percentage, generation of more FeO does not help the dephosphorisation process . Also you have to keep in mind that oxidation of P is an exothermic reaction and a reduced T always assists the P removal process.

That is correct.

I think, most of the research on pitting of stainless steels aim at developing a correlation between composition, microstructure, and pitting resistance. However, as mentioned, the corrosion process is very complex because the pitting is a stochastic process and influenced by pitting inducing anions (mostly Cl^-, but also SO₄^2-), pH, temperature, dissolved oxygen, concentration of other oxidizers and time. Pitting depends on the stability of the surface passive layer. The passive film stability is affected by small perturbations in the service conditions including stress level. With these many parameters affecting the process it is really difficult to propose a meaningful mathematical function to describe a pitting potential.

For materials selection, PREN is a good indicator. There are studies to correlate the pitting resistance using artificial intelligence, for example: Journal of Applied Logic 10 (2012) 291–297.

The argument behind the dissociation of perfect dislocation with Burgers vectors a/2<110> in two partials with Burgers a/6<112> is related to the dislocation energy which is roughly proportional to the square of the norm of the Burgers vector. Then, for a perfect dislocation, it is a²/2, while for a partial it is a²/6.

Since a²/2 > a²/6 + a²/6, the dissociation is energetically favored.

Best

L.

What you mentioned is the correct except that tapping density. We should always take experimental/true density of the powders/compound.

You can use radial view in ICP-OES

Here you can see the production steps: https://www.saar-hartmetall.de/english/produkte/rohteile.html

DRI or sponge iron refers to porous iron produced by the DR process. The DR process is a solid-state reaction process (i.e., solid–solid or solid–gas reaction) in which removable oxygen is removed from the iron oxide, using coal or reformed natural gas as reductants, below the melting and fusion point of the lump ore or agglomerates of fine ore. The external shape of the ore remains unchanged.

DRI has been fast gaining ground throughout the world since the 1980s mainly because of the shortage of coking coal for BF and steel scrap in steelmaking. DRI is produced by the DR of iron ore by using noncoking coal/ natural gas. The major part of DRI production is used as a substitute for scrap in steelmaking. DRI is consumed in three primary product forms, namely, lump, pellets, and hot briquettes (as shown in Fig. 10). The other secondary product form is cold briquettes made from DRI fines. The hot briquette form is popularly known as HBI. HBI is a combined solid form of DRI lump and pellets, hot pressed at 700–800C (973–1073 K), immediately after its production. The most important characteristics of HBI are its high density and lower specific area, which improves the resistance to reoxidation and makes it easier to handle. Due to high density, the charging of HBI in furnace is much easier and melting is faster. Tables 6 and 7 compare the chemical composition and physical properties of different forms of DRI.

Based on the types of reductant used, the DR processes can be broadly classified into two groups:

1. Using solid reductant, that is, coal-based DR process

2. Using gaseous reductant, that is, gas-based DR process

Coal-based processes

In coal-based DR processes, noncoking coal is used as reducing agent. In solid reduction processes, iron oxides together with solid reductant (noncoking coal) are charged into the reactor. The generation of reducing gas (mainly CO) takes place in the reduction reactor, and the product has to be separated from excess reductant, ash, and/or sulfur absorbing materials (lime, dolomite) by magnetic separation after discharge at low temperature, which makes product handling more complicated.[3] Because of the presence of these substances in DRI, hot briquetting and hot feeding are not possible for coal-based process. Magnetic separator also does not work at high temperatures to separate the DRI.

Gas-based processes

Reformed natural gas is used as a reducing agent. Iron ore lumps or pellets are reduced in the solid state and oxygen from iron oxide is removed by a gaseous reducing agent. Natural gas is reformed at 950C (1223 K), in the presence

of catalysts (Ni or Al2O3), to produce reducing gases CO and H2. The reducing gases H2, CO, or mixture of H2 and CO, are introduced into the reactor at elevated temperatures [up to 1000C (1273 K)] and pressure (up to 5 bars)[3]. If CH4 is present in the reducing gas, it results in carburization of the reduced product.

The processes based on gaseous reduction are confined to the areas where natural gas is available in abundance at a reasonable price.

The following are gas-based processes:

1. Retort processes HyL I, Hoganas

2. Shaft furnace processes Midrex, HyL III, Plasmared, Armco, Purofer, NSC, HyL IV

3. Fluidized bed processes FIOR, Finmet, Circored

DR processes are very sensitive to chemical and physical characteristics of raw materials used in the process. Iron ore or pellets, reductant (i.e., noncoking coal or natural gas), and limestone/dolomite are the main raw materials for DR technology. For successful operations the process of DR technology has specified the characteristics of raw materials to be used in the process.

Characteristics of iron ore: Lumps or pellets have high iron content, low gangue content, and good mechanical strength and are readily reducible and of nondecrepitating variety. Iron ore feed to the reactors has the following characteristics:

1. Chemical composition

2. Reduction properties

3. Physical characteristics

You wrote: " I have the reaction constant values, " what reaction rate constants doyou have values for andwhat are the units?

Hi all,

In my opinion, raw materials for arc-melting can be in form of powder or bulk (ingot, slugs, rod, scrap..)

- If they are in form of powder, i do agree with Jinghao that we should mix the powders as desired composition and then do green compact to form to pellet before arc melting so that powder blowing during arc-melting is minimized.

- If they are bulk form, it will be much easier for arc melting.

Noted: it is hardly controlled the temperature during arc-melting, so that some metals will be evaporated which make changing your alloy composition. some metals like Mg, Mn...could evaporate very quickly during arc-melting.

Hope it is usefull!

Dear Baskhar,

Interesting..

I observed Hysteresis like shape while heating and cooling polymer, can any one explain to me what is the cause of this hysteresis?

Dear Bhaskar;

You have three choices:

1. You can prepare a very thin composite to see sharp nanofibers in the FE-SEM images (This method is specially useful for hydrogels reinforced with nanofibers).

2. You can provide a cross section and see the dispersion of fillers in the coating matrix ( ).

3. You can used AFM analysis (topographic and phase contrast images) to investigate the nanofillers.

Good luck

Dear Bhaskar Bhatt,

I have attached herewith the list of High indexed conference in the world related to material science dedicated to composite.

01. http://www.ithec.de

02. https://emagbiocomp2018.sciencesconf.org

03. http://www.composites-europe.com

04. http://www.jeccomposites.com

05. http://www.nlr.org

I hope I have answered your question.

With Best Wishes,

Samir G. Pandya

The Tg measured with DSC and DMTA are not comparable quantities.

In DSC experiments the measurement of Tg should be done by cooling from the melt to the glassy state at given cooling rate (and this must be specified in any report). In DMTA the tests are influenced by both the cooling/heating rates and the test frequency. Changing the test frequency by a decade my give rise to Tg change of order of 4-5°C. The heating/cooling rates have similar effects. That is to say that if one uses very low testing frequency, f, and very low heating rate, H (namely , F=0.001Hz and H=0.1°C/min) the measured Tg may vary also 40-50°C in respect to faster heating and higher testing frequencies (namely, F=100Hz, H=10°C/min).

In all, the glass transition is a kinetics driven phenomenon . Thus is depends on the rates of testing (cooling/heating rates , test frequency and so on..)