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57th DEFENSE WORKING GROUP ON NONDESTRUCTIVE TESTING
17 through 19 November, 2009
NEW TECHNIQUE FOR RESIDUAL STRESS MEASUREMENT NDT
p.i. Ennio Curto.
Via E. di Velo, 84
36100 Vicenza (Italy)
This type of non-destructive method NDT provides the possibility to measure residual stress and the effect of the service load with an impact device and a vibration measurement sensor. Internal stresses are to be considered as the following: 1) Operational strains referring to loads that the material is subject and calculated 2) Residual stresses in the material caused by heat treatments or stresses caused by welding, forging, casting, etc. The new technique is able to measure the applied load and residual stress that are balanced on the surface of the material, and in a relatively large volume, at times even the same size as the entire structures. This stress is part of the metal’s elasticity field and has a three axis spatial orientation. The system works through the accelerometer mounted with a magnetic base to generate the acceleration value of the vibrations created by the device impacting on the metal surface.
The acceleration value, in combination with other parameters, permits obtaining the exact value of the residual stress or load applied in the desired point. This value will appear on the display directly in N / mm ². For non-magnetic metals, wax or gel will be used to mount the accelerometer.
This new system, for buildings, bridges steel inspection is very simple for to use , portable ,measure exact values of residual stress due to welding and the applied loads. After many years of research and tests, and between e discover about elastics behavior in field of metal steel now is very practice inspection point to point building and bridge constructions. This new system let bridges steel inspection in very simple mode, is portable instrument and let to measure exact values of residual stress due to welding and the applied loads.
Oct 11, 2009
More information about residual stress measurement NDT/NDE
The residual stress in a metal do not depend on it hardness, but from the module of elasticity or Young module and from its chemical composition (density).
The hardness of a metal indicates its ability to absorb energy elastic, plastic or kinetic energy, but through it not possible to determine the value of residual stress. In a metal with the same hardness we will have a different values of this stress. Therefore, the problem will be to measure the values that vary so exactly proportional to the residual stress values in a given metal.
The residual stresses tend to equilibrate themselves in the surface of the material.
The measurement made with all the major methods, X-ray, string gauge (destructive), optical etc. the residual stress is determined between the measuring the displacement of the equilibrium point the reticule crystalline.
The method discovered analyzes the value of acceleration vibratory generated by an impulse to constant energy with the subsequent reaction elastic (elastic field) from the metal, The equipment does not recognize the value of compression from that of tensile stress. It gives the value of the space resulting or volume but with the applying of a triaxial accelerometer we can have forces values axis x, y, z.
You will realize the convenience of this system.
1) Portable and easy to use and very rapid, high accuracy.
2) NDT/NDE non-destructive testing.
3) Repeatable in unlimited number of times.
4) Not dangerous (X-ray).
5) Do not expensive. Effective for welding, hardened treatments, vessels control, bridges, pipes line, aeronautics, NDT inspection for every metal types.
p.i Ennio Curto.
Hi Jon, sorry to comment a little late. The addition of natural fibers in PLA matrix did not improve HDT or thermal properties. However, chemical modification of natural fibers or and addition of mineral nanofillers produce a modification in HDT, Tm and Tg, as was reported recently by P. J. Jandas, S. Mohanty, S. K. Nayak (J Therm Anal Calorim
DOI 10.1007/s10973-013-3102-7). Tokoro et al. (2008) used Bamboo fibers untreated, alkaline treated and steam explotion fibers into PLA matrix. According with the results the thermal properties were improved by annealing at 110 oC for 5 h (J Mater Sci. 43(2), 775-787, 2008). In the literature you can find similar reports, and I am agree with you that this improvmeent is due to low thermal expantion coeff of natural fibers. Best wishes, Tomás Madera.
Hi everyone. Our group is currently building a magneto-optical Kerr effect (MOKE) magnetometer to study magnetic thin films. We're calibrating the system by comparing our MOKE measurements to VSM measurements on the same samples.
We've been noticing a strange horizontal shift in the loop that looks almost like exchange bias (See image). However, we don't see this in VSM measurements, so I think it's a problem with our MOKE setup.
Has anyone seen something like this? Or do you have any ideas what could be causing this? We're measuring the field using a Hall probe / Gaussmeter positioned right next to the sample between our electromagnet poles.
Tg is more for polymer pyhsicists. It is not defined by a single standard. It can be measured by several different methods such as DMA, dielectric spectroscopy, DSC, dilatometry etc. These methods do not necessarily give the same value and even with one method (e.g DMA, dielectric spectroscopy) the tan delta (or loss maximum) temperature depends on the temperature used (in the case of DSC on the heating rate). Glass transtion is rather kinetic than thermodynamic phenomenon. (I learned form an earlier discussion that some even doubt the existende of a second order thermodynamic transition aroun the Tg value). HDT (and Vicat) on the other hand is defined by a strict standard and is related to a fixed deformation. If you add filler and the modulus increases the given deformation is reached at somewhat higher temperature although the softening of the matrix maybe similar. In other case, when the volume of the polymer influenced by filler adsorption (interphase) is comparable with the total polymer volume a real and drastic change in Tg may be observed as well (in positive or in negative direction). The effect can be specially strong in the case of nanofilers.
I use a counterflow diffusion flame reactor for synthesizing ZnO nanorods. Because of the high temperatures in the flame I think the ZnO that forms melts in the flame and recrystallizes into a nanorod. I am looking for some help on the literature of recrystallization of ZnO. Can somebody suggest help me with that? I have been looking for almost 4 months now.
SiC cannot work up to 1700 degrees.... 1600 would be the maximum limit.
MoSi2 is the good option... Super kanthal ( Mo Si Alloy) is the best , I think you can go up to 1800 degrees ( but again its pushing too far)... it is available in market by Sandvik ( Super kanthal is a trade name) ..
What is the requirement?. Naturally it always best to give a protective environment for the heating elements. You get more life from them. Also your material should not be agitated ( like splashing etc.) the heating elements just breaks at these temperatures.
If you provide a gas tight atmosphere with a protective gas like argon .. you could use graphite heaters and go up to 2400 degrees ( max).
I would sugest a very clean aproach - I've seen it recenly. You need a transparent window and you heat the surface of intrest with a laser beam which runs through the window. If there is another window, you can capture the thermal radiation from the surface and with a radiation pirometer you cam measure the temperature. Them with a proper controller - posibly implemented on a PC and with the proper interfaces you can even control the surface temperature. Regards!
Basically, Tg can be defined as the temperature of molecular chains start to move by external force. So take normal polymer (semi-crystalline polymer) as an example, when polymer molecular structure becomes more ordering, the movements of molecular chains are constrained, which reflecting as the increase of Tg. On the contrast, Tg decreases. As you said, in order to change Tg without changing polymer composition, you can try to change polymer crystallinity, morphology (i.e. molecular size), and also the structure of single molecular chain (introduce branches to main molecular chains). These can be done by controlling cooling rate and isothermal time during heat treament, and polymer modification, respectively. On the other hand, increasing pressure to polymer will also increas molecular crowing and interaction, resulting increased Tg.
In addition to the imparted properties Vivek cited, carbon black is an excellent UV block to resist photochemical degradation of the rubber matrix. It is one of the cheapest and most effective UV stabilizers with an excellent track record. You could make white tyres if you wanted to add Titanium dioxide or zinc oxide but in environments with a moderate to high sulfur (pollution) content in the air, these may darken over time, so black is an excellent default color. Any other photochemical stabilizer besides carbon black or titanium dioxide would be orders of magnitude more expensive and not a thermally robust.
You have to specify which nanoparticle. I agree with you naked metallic particles do agglomerate but if you know the use e.g. conjugating with organic molecules. You can do by sonicating NP in mercaptopropionic acid less than 10mmolar solution. Metals readily react with above acid with thiol group. At the end you will have NP with COOH group ready for conjugation. In any means you must keep concentration of NP less than 100ug/ml.
Another way is during last part of synthesis you can add PEG 0.25% by weight and keep mixing for 10 minutes or more less than 90 degree ' C. Then follow the washing procedure. Above methods are not applicable to all. Regarding the CNT it is. Different story! !!!.
Prepare a TEM sample is not a simple task... If your material has a great ductility it is quite normal find out some scratches. Anyway, your analysis are is quite small and therefore scratches should not be a big problem. Forty microns is the thickness of the sample before ionic beam thinning, whilst actually the area under analysis must be much thinner...
The solidification voids that Dr. Mebane described occur in a cast billet or ingot that precedes forging. The purpose of forging is to break up the dendrites, (otherwise homogenize the composition), distribute voids throughout the total volume of the metal, and hopefully to "heal" the voids by making the hot metal interfaces fuse together (but see my third paragraph). It is best if the billet is forged in all three directions, preferably through two complete sequences (time is money, of course, so all this is not always done).
After all this general "upset" forging, the metal will then be hot forged either by rotating the metal between the platens of the press or simply squeezing in orthogonal directions (depending on what is most practical and what final dimensions are desired). The forged "bar" (rectangular or round) may still get more mechanical working such as rolling, drawing, or extruding to get to the final dimensions.
In addition to the various benefits or aligning and homogenizing the metal, the hope is that any residual voids are either so small and broadly distributed (and optimally aligned so that there is no significant stress transverse to the voids during use) or that they have "healed" completely. If, for some reason, the voids from the casting had a internal surface coating (intermetallic, oxide, carbide) that prevented achieving an essentially "perfect" condition, they may still be so minimized that they do not significantly reduce the strength or ductility of the metal (although those residual voids might still be crack initiation or propagation sites even though the product's strength is within nominal limits).
If the steel is being forged into a discrete part (die forged) as you imply describing a failed "forged component", it is even more likely that any original voids will have negligible effect on service durability due to the severity of the hot-working. However, if there was inadequate upset forging prior to this die forging, then the pre-existing voids are quite likely to initiate hot tears during the forging that lead to serious failure potential.
I face a problems are when i etched the sample some of the area is correctly etched remaining area is over etched and some times etching is good but etch pits are appearing so after this happened i want to remove those etch pits and over etching could you please suggest me
Nickel (Ni) with M. point 1453C is most soluble on in both gamma and alpha iron and a NON CARBIDE FORMER, can produce alloy steels with GREATER HARDENABILITY, HIGHER IMPACT STRENGTH and FATIGUE RESISTENCE than POSSIBLE WITH CARBON STEEL.
Ni produces a significant increase in toughness, even in the low temperature range, and is, therefore, alloyed for increasing toughness in case-hardening, heat-treatable and low temperature toughness steels.
Ni depresses the Ac and Ar critical points. It lowers the carbon content of the eutectoid. (with a 3.5% Nil steel, is reduced to 0.70% C). Ni on its own only makes the steel rust resistant, even in high percentages. At temperature above 593C, Ni-austenitic steels have greater high temperature strength, as their crystallization temperature is high.
[II] Now answer to the second part( Involves many terms need to be understood]:
[a]Austenite (named after William Chandler Roberts-Austen )also known as gamma phase iron , is a metallic, non-magnetic allotrope of iron or a solid solution of iron, with an alloying element.
[b] Austenite is a metallic, non-magnetic solid solution of C and Fe that exists in steel above the critical temperature of 723C. The FCC structure allows it to hold a high proportion of Carbon in solution.
[c]As it cools, this structure either breaks down into a mixture of ferrite and cementite (usually in the structural forms- pearlite or bainite), or undergoes a slight lattice distortion known as martensitic transformation. The rate of cooling determines the relative proportions of these materials and therefore the mechanical properties.
[d] Austenitization means to heat the iron, iron-based metal, or steel to a temperature at which it changes crystal structure from ferrite to austenite. An incomplete initial austenitization can leave undissolved carbides in the matrix
[e] An alloy containing 10% Ni becomes wholly austenitic if heated to 700°C.The range of stability of austenite increases with increasing Ni-content.
[f]The addition of certain other metals, such as Mn , can stabilize the austenitic structure, facilitating heat-treatment of low-alloy steels. In the extreme case of austenitic stainless steel, much higher alloy content makes this structure stable even at room temperature. On the other hand, such elements as Si, Mo, and Cr tend to de-stabilize austenite by raising the eutectoid temperature (the temperature where two phases, ferrite and cementite, become a single phase, austenite).
[g]The FCC structure allows it to hold a high proportion of carbon in solution. As it cools, this structure either breaks down into a mixture of ferrite and cementite (usually in the structural forms pearlite or bainite) or undergoes a slight lattice distortion known as martensitic transformation. The rate of cooling determines the relative proportions of these materials.
[h]Austenite can contain far more carbon than ferrite, between 0.8% at 723°C and 2.08% at 1148°C. ABOVE CRITICAL TEMPERATURE, ALL THE CARBON CONTAINED IN THE FERRITE AND CEMENTITE(for a steel of 0.8% C) IS DISSOLVED IN THE AUSTENITE.
[i] Iron transforms from (FCC) structure ( gamma phase), or austenite ( at high temperature) to a BCC structure(alpha phase), or ferrite (at a lower temperature).
[j] In FCC Fe atoms occupy the LATTICE SITES and carbon atoms occupy the INTERSTITIAL SITES. In the low-temperature (ferrite structure), or BCC structure, there is no room for carbon atoms.
[k] At 750C, two things occur: the carbon bonds with available iron atoms form Fe3C, an INTERMATALLIC COMPOUND called cementite, or iron carbide, and it precipitates out as a discrete structure; the remaining austenite then transforms to ferrite consisting of alternating layers of ferrite and iron carbide.
You have different aspects. I am assuming that you have strong microssegragation after solidification. In this case the diffusion annealing for homogenization must be done close to the solidus line of the steel alloy, 50 to 100oC below, and use time from 24 to 48 hours depending on the material size and weight. Hot deformation is usefull because reduces the interdendritic spacing and increases the homogenization rate. You can use both process together.
I have studied the effect of Ni on the microstructure of an Al-12Zn-2.5Mg-2.5Cu alloy. Some Al3Ni intermetallics were seen when 3 and 5 wt. % Ni was added although we have not still reached eutectic point (5.7 wt. % for binary Al-Ni alloy), intermetallics were somewhat coarse. Is it possible to say eutectic point has shifted left and thus primary intermetallics have formed? How can we be sure?
What is the influence of solution treatment (time and temperature) on microstructure of alloyed copper or different copper alloys?
Aug 10, 2012
This is a very broad question because different copper alloy may behave differently. But most of alloy would provide you coarse grains, and more solute dissoved in the solution as you increase the time and the temperatures (below the melting point)
What is the difference between AA2014 T6 and AA2014 T651 in their mechanical properties?
I run experiments on alluminium alloys 2xxx series, especially AA2014 for aircraft components. I just know the difference between T6 and T651 in their temper mechanism. How about mechanical properties? hardness, ductility, and their micro structure?
The T651 temper involves mechanically stress relieving the material after solution heat treatment by stretching it 1.5 - 3% prior to aging (precipitation hardening). (The residual stresses come from the quenching that results in faster cooling at the surface than the interior.) There is no noticeable change in the mechanical properties or the machinability. However, with the stress relief, when machining the raw material more from one surface than the opposite one, there is less likelihood of the metal spontaneously relieving itself over time and causing warpage or distortion. If, for example, one had some 4 cm thick bar and a slot 1.5 cm were cut on one face, the bar (in the T6 condition) might bend around that slot whereas it would be less likely to if in the T651 condition. This will be true for any heat treatable aluminum alloy, whether it have a T351, T451, T651, or T7351 treatment.
I am about to make antibacterial polymer, but the problem is that I don't know what the right compounds to get plasma coating. What are solutions, voltage, and current should I use to get a plasma coating?
Taking into account that copper is one of the best conducting materials, I do not see the reason for this combination, unless some special effects is anticipated. Do you mean graphene, carbon nanotube or carbon black? What would be the composition and the distribution of the components (surface of bulk)? What is the context of you research?
You may use thermodynamic software like Thermo-Calc (http://www.thermocalc.se/) to produce phases for your desired alloys. I did for other alloys composition, it worked well. Unfortunately, i don't have registered version now. You may ask other people who are using Thermo-Calc.
With all due respect, none of us is at the Nebuchadnezzar ship. Knowing about this matters involves rheometry, physics, chemistry, material balance, thermodynamics, among others. There is no single book neither a single paper -even a review- which can explain all of the possibilities when dealing with screws configuration. You will see the more extreme case if you take a look at the BUSS webpage, the best continous mixer in the world. Another option is to find somebody having a lot of experience with twin screws an mixing/blending.
Sorry for my statement but I will tell you that you will not find a recipe that would suit you. Why? because the process parameters are very dependent on a lot of factors and first of all the type and configuration of your system. I will tell you that even the same type of systems would perform differently and would give you different results if they were not tuned using the same reference set points. Please correct me if I wrong but I understand that you are new to dry etching otherwise you would not request the recipe that would not touch your photoresist. Your photoresist will be etching you like it or not. There is only matter how fast it will be etched in relation to your material. That called as selectivity. Usually people go another way: first, they would determine the process that would give them the maximum selectivity and then based on the thickness of your materials that you need to etch you make your mask. Thanks, Andrew
I synthesized Ni nanoparticles by Hydrazine reduction of NiCl2.
Calculation of cooling rate from measured data of temperature
Jun 6, 2012
I have done heat transfer studies during TIG welding process. I plotted temperature vs. time and I used centered difference method to calculate cooling rate at every instant from the measured temperature data. I found the slope of cooling rate (Y) vs. time (X) plot becomes zero say at 100sec, whereas temperature (Y) vs. time (X)curve slope becomes zero at 600sec. Could anyone explain?
Is the molar volume just additive of the weighted molar volumes of two elements, or should I use vegard theory to calculate lattice constant when B is substituting A in a cubic (for example) lattice and from there calculate volume? Which is the best assumption?
Let me observe that the "optimum thickness" is obtained by a correlation between cost and cold face requeriments. Normally, to general purposes, cold faces have the maximum of 60ºC, or 333K, in the surface. In some industrial cases, this temperature can be higher.
The calculation of the thickness in this condition is gave by:
1) Calculation of the global heat transfer coeficient (U): U=Q/(A x (T hot face-T cold face));
2) The tickness will be give by: L = k.[1/U-1/h (hot face)-1/h (cold face), were h is the convection coeficient and k is a characteristic of the material and gave in "W/m.K".
3) Normally can be used the minimun quantity of thermal insulation and several kinds of insulations with diferent "k", and cost, can be tested in the selected calculation method.
The most detailled methods to calculate the "optimum thickness" can be localized in the Heat Transfer literature.
Both alloys will be similarly corroded ("corrosive" applies to the acid, not the affected metal) by HCl. I don't know if there are published values of corrosion potential or current (either of which may be affected by other factors such as temperature, purity of the solution, amount of circulation ...). You might look on the National Association of Corrosion Engineers (NACE) website
The quick answer is YES. HDT is related to the heat needed for material deformation. Such heat increases as the quantity and/or size of crystals are growth, therefore HDT is hightened. This value is always below Tm, the closer, the harder to increase.
Please visit http://materialsscienceengineeringdefined.blogspot.com I would be pleased to have your comments, critism and/or ideas of themes you feel I ought to develop (clarify) further.
Why not contribute if so inclined. cf any of my interlinked sites.
Best wishes and hope my site helps the field and the researchers on wider issues
July 14, 2011 – Irvine, CA – Nanovea today introduced its patent pending breakthrough method of reliably acquiring yield strength through indentation; ultimately replacing the traditional tensile testing machine for yield strength measurement.
Traditionally yield strength has been tested by using a tensile testing machine, a large instrument requiring enormous strength to pull apart metal, plastic and others. The yield strength (also known as yield point) of a material in engineering (and or materials science) is the point of stress that a material starts to deform plastically. Before reaching the yield point a material will deform elastically but returns to its original shape when stress is removed. A crucial material property for nano and micro related materials found in advancing industries such as biomedical, microelectronics, energy and many others. Until now the most reliable way took large machine effort, sample preparation, and or was impossible to perform on small samples and localized areas.
Interesting update on a stalwart test. I first ran tensile tests on donated equipment at my high school, back around 1970! We also had Brinell testers, Shore, etc. A real walk down memory lane.
I look forward to reading more about the nanovea system.
magnesium and its alloy C. scheldon roberts
Jul 5, 2011
I want this book.If anyone download this book then please send me on email@example.com
Jul 15, 2011
Magnesium: Proceedings of the 7th International Conference on Magnesium ...
By K. U. Kainer
Developement of magnesium and it's alloy
Jun 29, 2011
I am sonam. I am doing M.E. in material technology. My project topic is " Developement of magnesium and it's alloy". I want ur valuable suggestion related to this field. How can i improve it's properties, processes, etc....
nanodispersions are good at reducing oxygen in crystal latices...and hence better corrosion resistance. I'm doing a project on this issue at the moment. By having more uniform latices, most of the physical properties are enhanced as well.
There are numerous areas - in fact, for any kind of material or application you can imagine, research is being conducted. Biomaterials, solar energy conversion, energy storage, semiconductors and chips, ballistic-protection, amorphous materials, adhesives, composites, graphene ...
Places where you can look for topics are annual technical conferences organized by ASM International, the Materials Research Society (MRS), the Institute of Metals (U.K.), and similar professional societies. Titles of individual conference sessions or presentations over several recent years of these conferences should give you a pretty good overall view of what is going on in materials science today.
hi every1, pls I will like to have some materials on ICE piston construction from A to Z. This is to enable me work on my project which is on construction of piston using an Al alloy composite. Thank you so much for your help;God bless you,amen.
Can any one kindly explain me the concept of Percolation. I am an electrical engineer and i need to know about conductive plastics. when i am referring about them, i have come across this Percolation concept which i didnt understand... Kindly provide me some papers or literature about Percolation.
If the electrical conductivity is required in a polymer, then indeed instead of trying to prepare an intrinsically conducting polymer, it is much easier to introduce conductive fillers in the polymer matrix. The percolation threshold is reached when the insulator - conductor transition is observed. Generally, it is better to use as less filler as possible for getting the conductive regime. This is possible through the use of fillers having a high aspect ratio, either fibres or flakes. Carbon particles can meet these requirements (see attachement), whether they belong to one or the other kind of filler. Additionally, their density is low, so that the weight of the resultant composite is not significantly higher than that of the neat polymer, and they are usually cheap.
Hi everyone,I am vinay working on diesel engine with thermal barrier coatings.some one plz help me finding out the process parameters of Lanthanum zirconate using plasma spray coating technique.And plz do help me out in procuring or preparation of lanthanum zirconate at low cost on a bulk.
Hi everyone,I am vinay,I m working on diesel engine with thermal barrier coatings.some one plz help in finding out the process parameters for Lanthanum zirconate using plasma spray coating technique and also procuring or preparing Lanthanum zirconate at low cost on a bulk.Thank you in advance.
hi everyone..i am supposed to study the microstructure of commercial grade stainless steel. what is the best etching solution? also i am not given the composition of the alloy and i need to identify the phases. can anyone enlighten me??
A deformation-processed Al-matrix/Ca-nanofilamentary composi...
Materials science: InTech Open Access books
Jan 17, 2011
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Hello Dierk, many thanks for useful links and valuable information. You are really advanced in this area. I remember this Max-Plank Inst web-site, but you recalled it to me. What about my initial questions. Your opinion is interesting on microstructure models verification and SPD industrial implementation.
shape-memory alloy is an alloy that can be deformed when cold but returns to its pre-deformed ("remembered") shape when heated. It may also be called memory metal, memory alloy, smart metal, smart alloy, or muscle wire.
Parts made of shape-memory alloys can be lightweight, solid-state alternatives to conventional actuators such as hydraulic, pneumatic, and motor-based systems. They can also be used to make hermetic joints in metal tubing.
hello i m ranvir. i m working on a project related to aluminium alloy reinforced with ceramics by stir casting process. i want ur valuable suggestion related to this field. how can i improve the composite properties in reference to bullet proof materials.
Aluminum alloys reinforced with ceramic billets seems to be a fairly wise option to enhance ballistic resistance of bullet proofing materials. Often Alumina billets, 5-10 mm in size when dispersed in Aluminum alloy matrix might be promising, but care should be ensured that the ceramic volume fraction is not too high and finally stir casting process may not be suitable in cases where the reinforcement is large unlike PRMMCs, Thixocasting or squeeze casting or pressureless infiltration processes are best suited for realizing these applications.
Invitation for Highly Qualified Reviewers for the INTERNATIONAL JOURNALS having good IMPACT FACTOR:
'Hydration' word represent presence of water. To stop hydration- don't use water during mixing as well as during curing. You can use any solvent stated above as well as any thin oil.
Investigation of shrinkage cracks in term of size of cracks can be done by microscopic study, Apparent porosity, UPV and Permeability will give an idea of the extent of damage.
Yes, ThermoCalc is a suitable software for for calculating the liquidus surface of a ternary phase diagram. Depending on the version, you may be required to download a software in order to view the liquidus projection in 3D. For example, using TCC Version S, the software needed is Wirtual Reality Modelling Language (WRML) which can be downloaded from http://www.cortona3d.com/Products/Cortona-3D-Viewer.aspx (Cortona3D Viewer).
Here is some information about how to use ThermoCalc softwares:
In materials with a large exciton binding energy, it is possible for a photon to have just barely enough energy to create an exciton (bound electron–hole pair), but not enough energy to separate the electron and hole (which are electrically attracted to each other). In this situation, there is a distinction between "optical bandgap" and "electrical band gap" (or "transport gap"). The optical bandgap is the threshold for photons to be absorbed, while the transport gap is the threshold for creating an electron–hole pair that is not bound together. (The optical bandgap is at a lower energy than the transport gap.)
In almost all inorganic semiconductors, such as silicon, gallium arsenide, etc., there is very little interaction between electrons and holes (very small exciton binding energy), and therefore the optical and electronic bandgap are essentially identical, and the distinction between them is ignored. However, in some systems, including organic semiconductors, the distinction may be significant. See: http://en.wikipedia.org/wiki/Band_gap
It is very difficult to propose useful reference for you since I do not know materials investigated by you. In the case of semiconductor materials, band gap can be evaluated based on the results of photoluminescence measurements. Usually, the excitonic lines are observed in the photoluminescence spectra. The energy of these lines allows to obtain the value of band gap with an accuracy of a few tens of meV It is very better than the determination of band gap using the absorption measurements. Good luck to you.
Nov 11, 2011
Can anyone suggest me references towards how the activation energy for boundary sliding (During plastic/superplastic deformation) vary with increasing temperature?
I'm in need of designing a bob for a rotational viscometer which have to withstand high temperatures. The weight of the bob should not exceed 500g. Can anyone tell me the best material that can be used (it should be cost effective too)
Fe is the cheapest. You just need to maintain the oxygen partial pressure in your furnace below 10pow(-12) atm. You can use an Fe crucible. It should be pure iron with least impurities possible. However with this material you can do measurements upto 1460 degrees.
Again the material choice would depend on the system you are studying. It crucible and the bob should not react with your molten fluid. In case it reacts the best option is either Mo or Pt/ Pt-Rh alloys.
I am looking for an effective means of melt blending polyamide 6,6 with POSS nanoparticles and my challenge is how I can uniformly disperse the nanoparticles in the blend. The POSS I am using has a higher melting temperature than Polyamide 6,6 thus will remain solid (nanoparticle) during the entire process of melt blending. Also, worth noting is that quantity of POSS compared to Polyamide 6,6 in the mixture is small, less than 10%wt.
Thanks for reply. I will check out the citation and try to find my answers.
I need "The Science and Engineering of Materials by Donald R. Askeland" book.
Sep 27, 2011
I need "The Science and Engineering of Materials by Donald R. Askeland" book.If anybody download this book then please send me on my email "firstname.lastname@example.org".
link : http://ebookee.org/The-Science-and-Engineering-of-Materials_1290861.html
There is a conference on the subject in late October in Worcester, MA, USA. You can find a list of presentations and authors at http://www.asminternational.org/content/Events/coldspray/. By following up with that (or with previous Cold Spray conferences sponsored by ASM) you should be able to get an impression about what is going on in the field.
The two arcs means you are well resolved the two different path ways of conduction. It can be grain and grain boundary paths. you refer to Impedance spectroscopy by Mc.Donald, for further reference, or any mannual for impedance spectroscopy unit (solatron) in internet.
dear friend , the industrial use of carbon nano fiber is limited by the post processing required. The purification of the fibers should not affect the properties of the fibers. This is a major concern.
Impregnate a ceramic cup filter with Silver nanoparticles (AgNPS) suspension. A ceramic filter was first immersed in AgNPs suspension (0.22 g/L silver nanoparticles dispersed in deionized water) for 24 hr . The ceramic filter was removed from the AgNPs suspension and allow to dry at 50 0C for two hrs. After drying, the ceramic filter was washed two to three time to remove excess AgNPs. Then the ceramic filter is ready to be used .