- Jyun-Sheng Wang added an answer:2Any advice with Finite-rate/Eddy-dissipation model with surface reaction?
I got another problem with finite rate/eddy dissipation model using surface reaction.
The surface reaction was activated by
1.Model→Species transport→check "Wall surface"
2.Assign material in mixture to "Site species"
3.Material→Mixture→Create "Wall Surface Reaction" and "Mechanism"
3.Boundary conditions→ check "Reaction"→ assign "Site species"
However, I saw that the wall surface reaction only used finite-rate model setup.
The setup of Eddy dissipation mode was disabled and turn grey on the setup panel.
Running the simulation and check contour of "Rate of Reaction", and then there was no rate of reaction.
The value of rate of reaction is 0.
However, the Kinetic Rate of Reaction had some values.
I checked the description in "34.4. Alphabetical Listing of Field Variables and Their Definitions."
Rate of Reaction-n
(in the Reactions... category) is the effective rate of progress of th reaction. For the finite-rate model, the value is the same as the Kinetic Rate of Reaction-n. For the eddy-dissipation model, the value is equivalent to the Turbulent Rate of Reaction-n. For the finite-rate/eddy-dissipation model, it is the lesser of the two.
Does it mean that surface reaction could not be simulated using Finite-rate/Eddy dissipation model?
Is there another way?
The effective rate of reaction is zero, Turbulent Rate of Reaction is zero, and Kinetic Rate of Reaction is not zero.
However, there is indeed product generation into the domain.
This is weird. I wonder why and how do I treat the result?Following
- Closed account added an answer:8Is it impossible to apply the nickel-base superalloy fabricated through PM route(HIPing) to the turbine blades instead of the cast one?
I think there are some reasons, but I can't find that.
In my thought, the HIPed superalloy is homogeneous, has no porosity there and many advantages.
So, there are many cases of the applications for turbine discs.
However, it seems that there is no application for turbine blades even though the HIP is used for rejuvenation of turbine blades due to the reduction of porosity.
In my reference book, it is explained that the wrought alloy is used for the intermediate-temperatrature and the cast alloy is for high-temperature.
Unfortunately, the book didn't answer why.
If there is any case. please introduce to me.
There is one more problem, in new design of gas turbines, cooling is very important factor and thus cooling holes in blades for film cooling are necessary and almost these holes produced by core in casting. I think that it would be impossible to make this holes by PM.Following
- Lech Pawlowski added an answer:17Do you know the industrial application of the photocatalytic effect on titania surfaces?The effect was shown by Fujishima and Honda in 1972 and occurs in the presence of titania, water and uv radiation. It leads to the degradation of pollutants and may be for example applied to the formation of self-cleaning surfaces.
To Dr. Ochiai,
Thank you for the useful information.Following
- Dr. Trevor John Hutley added an answer:14Does Nylon 6,6 undergo any thermal degradation at 232degC that could result in a loss of properties?
I am using Nylon 6,6 fibre veils to toughen composite laminates and I have noticed that the results are good when they are used with a resin cured at 180degC and substantially better than when they are used with a resin of similar chemistry but cured at 185degC and postcured at 232degC. I was wondering if this could perhaps be caused by some thermal degradation of the Nylon fibres (I am aware that this is not above the melting temperature of the fibres). Any insight would be greatly appreciated!
I would suggest that you define more precisely your question.
When you write about curing, post-curing and degradation, you need to give time as well as temperature as part of the description.
When you write about mechanical properties, try to be more quantitative.
Saying that "the results are good" or "substantially better" is vague!
Nylon 66 degradation is complex. I have seen papers in which spectroscopic changes occur within 30 minutes at 120°C. That may not be "catastrophic degradation" but it may be the basis of changes in surface energy or end-group chemistry that could result in changes in toughness. At 232°C, it is likely that some degradation processes will be starting. The impact of these processes will depend on fibre properties (such as end group chemistry, molecular weight) and on the presence of oxygen.Following
- Ashkan Khalili added an answer:6Node Rotation to Define Elements while Using UEL?
I'm working on UEL and recently I've developed a shell element. To define an element in input file, I'm using counter-clockwise rotation for nodes. With just just one element everything is good. When I'm trying to couple bunch of elements in a row together it's giving me some weird results. I realized that if I define different node rotations (to define elements in input file), for elements next to each other, it will work. Let's say I want to couple four elements together. Normally I should use counter-clockwise node rotation for all of them but, here I must use counter-clockwise for the first one, clockwise for the second one, counter-clockwise for the third one and clockwise for the fourth one.
Would you please let me know why that is and how I can fix it up?
Thanks for your consideration and response.
I will be in touch with you via EMail.
- Azaam Aziz added an answer:6Is there a sacrificial layer, other than photoresist?
I have used photoresist as a sacrificial layer but is there anything else which can be used as sacrificial layer which should be easily soluble in ethanol or acetone?
I can't use sonication in my case as after spin coated resist I deposited a bi-layer configuratrion of SiO/SiO2 to make rolled-up microtubes. The tubes start to roll after removal of sacrificial layer. But photopresist is not moving away after reactive ion etching means chemical properties of photoresist has been changed after etching and no more soluble in acetone.
I already used remover designed for my photoresist AR P 3510.Following
- S. Ulamec added an answer:3What are the possible materials that are used in Philae?
I want people to discuss under that question about the possible materials which are used in Philae. What are their manufacturing process and I am also interested in electrochemical manufacturing processes. If anyone send me a beneficial link or source about it I will appreciate.
Thanks in advance.
The main structure of Philae is made of carbon fibre and carbon fibre with aluminum honeycomb.
Obviously, there is a huge number of other materials used for the subsystems.
Additional structural elements and mechanisms are to a large extent made of aluminum, titanium and certain, space qualified, plastic materials.
Do you have any specific interest in a particular material?Following
- Mirosław Stygar added an answer:12What is a suitable Etchant for Al 6061?I want to see the grain boundaries of Al 6061, so what is the proper etchant and what is the etching procedure? I tries Kellers reagent but it still doesn't work.
Hello, I found this in "Metallography and Microstructures 2004 - Vol. 9 ASM Handbook".
Please look at attached file.
Best regards and also good luck :-)Following
- L. Veleva added an answer:7Is there a correlation between accelerated current corrosion and normal current corrosion, which can be compared in reinforced concrete structures?
How can the factors be manipulated to assess the relation between the two cases?
If we do an experiment using accelerated current corrosion under a period of time, how would it help to assess the amount of corrosion under normal condition for the given period of time?
I hope that the articles in attach.files could be some answers.
- Keerthana Ram added an answer:2Does anyone have experience with hydrogel synthesis using liquid nitrogen?
Would synthesis of polyvinyl alcohol hydrogels be achieved using flash freezing with liquid nitrogen? (freeze-thaw method)
Recently, one research group from korea has been published an excellent work based on formation of PVA hydrogel with contacting one end of polymer solution to LN2 surface. PLease find the attachment of article which may provide some ideas for you.Following
- Carlos Araújo Queiroz added an answer:2Why is geopolymerization an exothermic process?
The first part- "dissolution" is clearly exothermic process, with consuming water. But why second part "polycondensation" is exothermic? I think that the realease of water should be endothermic.
I attached the conceptual model
For a discussion focusing structural aspects from geopolymerization of inorganic polysialates you may check sections 7-8 at: J. Šesták, C.A. Queiroz, B. Foller, Ch. 3 in: D. Křemenáková, R. Mishra, J. Militký, J. Šesták (Eds.), "Selected topics of textile and material science", Publishing House of West Bohemian University, Pilsen, 2011, pp. 53-75.Following
- Nicolas Charvin added an answer:8What kind of heated transfer line would you use for a custom humidity generator ?
Our lab develop a custom setup to control %RH in the sample chamber (volume: 1 liter). It works fine at room temperature, but condensation and droplets appear when temperature increase in the chamber. Commercial products offer heated transfer lines between the humidity generator and the chamber, but I couldn't find any details about what kind of lines they use.
I need to flow up to 5 L/minute over 2 meters.
Any advices ?
Thank you all for your hints and feedback. Actually, we choose a quick and dirty hack to avoid condensation inside the tubes: we put the whole bubbling-device into a thermal-chamber, heated at (temperature in sample chamber + 10°C).
We tried to minimize the length of the tube between the chambers, and we use passive insulation (foam).
But the main "issue" is currently that, while the air in the sample chamber is at, say, 70°C, sample holder and chamber walls are colder (~45°C), and thus condensation appears. The manufacturer says the instrument is designed to handle this, so...
Finally, we manage to reach 0% --> 60% RH at 70°C, which is correct for preliminary tests.
- Gert Nolze added an answer:32What is XRD+Rietveld phase fraction detection limit?
Hello my fellow scientists
I have a question regarding a Rietveld analysis that I have done on an XRD pattern. I have done XRD on a microalloyed steel and when I do the refinement with GSAS it tells me that the volume fraction of a (Nb,Ti) (C,N) is 0.056% which is a pretty low volume fraction. In your opinion is this number reliable given the 1% error that we consider for XRD.
I should mention that the 0.056% is actually expected and correlates well with thermodynamic calculation. But strictly from XRD stand point, does it have any significance. How can I mention this in a paper without raising eyebrows?
Thanks in advance,
Hi Ian, I guess he used a monochromator or an energy discriminating detector. This signal is definitely not the original Cu signal.Following
- Supratim Mitra added an answer:13How can you optimize the poling condition (applied field, temperature, time duration) for a ferroelectric material?For poling of a ferroelectric materials it is exposed under a DC field (> Ec) to align the random electric dipole for a time duration preferably below its Curie-temperature (Tc), and then field cooled to freeze the dipoles alignment. But quantitatively what would be these values of field, time and temperature?
Dear Dr. Sreenivas,
thank you giving the detail technique of poling, however few questions remain in my mind, is it good to cool the sample faster with field on and secondly, how to monitor such low current passing through the sample.
Thank you again for spending your time and energy to address my query.
- NISHA SHANKHWAR added an answer:4Is there an electrospun nanofiber mat which can withstand large amount of stress?
Which material should I use to produce the nanofibers? What are the parameters to obtain the maximum endurance to stress possible? Thank you so much!Following
- Lin Yang added an answer:4How can I make pure β-C2S?
I tried to make pure β-C2S using burning method in the lab, however, failed. The pulverization of C2S during cooling is the main reason as the β phase transform into γ phase. Is there better way to do it please?
I did, but no effect. Did you make it please?Following
- Mobinul Islam added an answer:6How can I have a PVP concentration of 0.36M?
I do not understand how can I have a concentration of 0.36molPVP K30/L EG if the molecular weight (Mw) of PVP is about 40.000, therefore I would need too many PVP to get to that concentration. Could anybody tell me if it is ok to have all that PVP or I am doing it wrong. Thank you.
Calculate the mass of vinylpyrrolidone (111.14 gm) for preparing molar solution. Average MW of PVP determine your desirable polymer chain length. If you want to use PVP as a matrix to form a gel with, you have to use larger chains. OR If you want to use it as a capping agent ; then smaller PVP molecules should be selected so that they are less likely to bind the multiple particles and coat the particle one by one.Following
- Mallikarjuna Balichakra added an answer:4What are the properties of Nitinol materials such as temperature wrt conductivity, specific heat and density?
Temperature(c) conductivity(w/m k) Specific heat Density(kg/m3)
25 6.5 60 4470
thanks to allFollowing
- Ali Alkunie added an answer:15Whats the best method to predict fatigue life of steel welded joint?
whats the best method to predict fatigue life of steel welded joint?
Thanks alexandre for your answer .i am now doing
research on microstructure effect on fatigue life and im interested in your research about ca6nm steel .i hope if i could some information about your experimental set up.Following
- Surya Vn added an answer:5What is the most durable piezoelectric material (or piezoelectric composite material) subjected to the repeated compressive loadings?
I am looking for the best cadidate material which has piezoelectricity in response to compressive loadings and also shows excellent durability. The piezoelectric material would be ceramics (ex. PZT) or polymers (ex. PVDF) or composites (ex. ZnO embedded polymer composites). The type of the material does not matter. Thank you for your interest.
Piezoelectric Ceramics can load similar WeightFollowing
- Lutz-Michael Berger added an answer:7How do you measure the oxygen content in HVOF coatings?
The coating is of 86WC-10C0-4Cr type. The advanced HVAF coatings are considered lower in oxygen content than HVOF.
How to ascertain?
You can expect an integral Oxygen Content of 0.3-0.5 %, such values are reported in the literature. Best way is to measure from detached coating (required mass is very small) with a Commercial Oxygen/Nitrogen Analyzer (Company LECO). But correct name of the method is "carrier gas hot extraction".Following
- Priyavrat Thareja added an answer:3Is it necessary to the zinc phosphate process for especially for lubricant before cold drawing of stainless steel?
Before cold drawing of stainless steel, zinc phosphate process is necessary or not?
With zinc phosphate process, the wire is taking soap for drawing steel but for stainless steel, any different application?
You can see:
Experimental study of the lubrication by soaps in stainless steel wire drawing
Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology September 2011 225: 915-923,Following
- Chen tiam foo added an answer:14How can increase the quantity of monomer flow into the reactor chamber and reduce the leakage of the piping connection at the monomer inlet?
The monomer I used was heptylamine.
I did for warming up the monomer by immersed the bottom flask in the water bath. I used the heating tape to warmed the SS piping as well and the SS piping had the heptylamine odor strongly.
However, it showed air plasma reaction (pink color) once turned on the RF power. Heptylamine seem doesn't flow into the chamber because it doesn't have any odour of Heptylamine inside the chamber.
How can I improve the system to gain more monomer flow into the chamber? Any methods to tighten the bottom flask to holds the stainless piping？(Figure 1)
Thank you for sharing the knowledge that you have.
- Javed Kamran added an answer:4What is the Relationship between misorientation angles/axis & angle/axis for coincidence site lattices.Can these be related to deformation mechanism?
I am working on evolution of microstructure and texture of magnesium based alloys during heavy reduction. I need to know the role of Σ5a ,Σ17a, Σ19a and Σ27a, CSL boundaries in terms of dynamic recrystallization (DRX), static recrystallization SRX, and deformation behavior of magnesium alloys.
Dear Dierk Raabe
Than you very much for providing such a useful information.
- Pavlo Zolotavin added an answer:8Is it normal to observe many bubbles during heating up of a mixture containing oleic acid, 1-octadene and lanthanide acetate solution?
When the temperature is close to 120oC under stirring (I need to heat up to 150oC form lanthanide oleate), suddenly a vast amount of bubble give out like soaps and they eventually disappear. It is a bit strange because I dont observe vast amount of bubbles before. I afraid this was one of the factor affect my nanocrystal synthesis.
Before the existence of the bubbles, the mixture stay a bit turbid and the mixture become clear again after the bubble evaporation. Actually, I suspect the destruction of oleic acid as indicated by the vast amount of bubbles
Could it be boiling off of the acetic acid after you form a lanthanide oleate? The boiling temperature for it is about 120C... Orange brown color of your nanoparticle solution would probably mean that either you did not form any nanoparticles or your particles are too small to scatter light efficiently. Hope this helps.Following
- Tarık Ömer Oğurtanı added an answer:11What value of plastic strain can I take for aluminium?
I would like to know the general value of plastic strain, in order to use that value in my abaqus input file. The model is a foam made up of aluminum.
Actually there is confusion in the terminolgy, the 0.2 percent yield strength also called the 0.2 percent offset yield strength, which is also named as nominal strain by engineers, determined from the engineering stress strain diagram, as Alberto mentioned in his remark above. All those engineering concepts are misleading since they depend on the geometry of specimens, and characteristics of the measuring devices and methods. Plus they don't mean very much for the material scientists either who are dealing with the mechanism of plastic deformations in solids in micro and/or nano metric sizes. BEST REGARDSFollowing
- Rana Afif Majed Anaee added an answer:2What is the best way to obtain the Zn-Ni deposit on Mg AZ91D alloy?
I'm doing my thesis on electro-deposition of Zn-Ni on Mg AZ91D alloy. I tried to coat the substrate by the following experimental way and the result turned out to be bad, the Zn-Ni coating was very brittle and lacked adherence to the substrate.
Process sequence which I followed,
2. Activation in citric acid (100g/l), T=25°C, t= 45 sec
3.conditioning in sodium hydroxide (200g/l), T= 65°C,t=30min
4.Dilute cleaning in citric acid (10g/l), T=25°C,t=10sec
5.Zinc immersion, T=80±2°C,t=6min, compsition is as follows
- Zinc sulphate – 30g/L
- Potassium pyrophosphite– 110 g/L
- Sodium fluoride – 5 g/L
- sodium carbonate - 5 g/L
6.Electroless Ni plating, T=80±2°C,t=1hr, compsition is as follows
- Nickel sulphate – 15g/L
- sodium acetate– 13g/L
- sodium hypophosphite - 14 g/L
- Ammonium hydrogen difluoride - 8g/L
- Thiourea - 1 mg/L
- Hydroflouric acid - 12 ml/L
The use of chromium trioxide is banned in my laboratory and so I couldn't use it in the pretreatment. Kindly suggest me some alternative pretreatment steps/eletroless process to get a better Zn-Ni deposit on Mg. Any comments or tips would highly be appreciated, also I'm attaching the pic of my processed sample.
You can use electroplating, hot spraying and atomaization.
- Sornadurai Dharmadoss added an answer:14What is the best way to prepare a sample of zirconium for ebsd analysis?
I am working in zirconium and I am facing difficulties in getting my sample prepared for EBSD.
My Zr sample is hot rolled and cuboidal in shape with dimensions (approx) 2.5 mm X 2.5 mm X 5 mm. I did manual polishing using SiC papers of grit size 600 , 1000,1500,2000,2500. Then used diamond paste of 0.5-1 Micrometer, followed by colloidal silica of 0.05 micrometer. I electropolished the sample using struers lectropol-5 and struers A3 electrolyte. Volt-28V, time-60sec, room temp
Separately,I also electropolished using 20:80 solution of perchloric acid and methanol at -30 celsius ,20V,20sec.
I did ebsd using SEM. I am getting good kikuchi pattterns but my average CI is very low (<0.05)
Dear Gert Nolze
I also agree with this image quality. One can also adjust in one tenth of mm. So that obtain a good Image.Following
- Pedro Lira added an answer:6Does anyone have Id x Vgs and Id x Vd measurements of any organic field effect transistor?
I'm only finding plotted graphs. But I needed all the measurement values (Id Vgs, Id Vd) of transfer and output curves in order to test my simulations.
Thanks a lot.
Thanks a lot, Mr. Shallouf.Following
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