How to measure the stoichiometric variations during sintering?

11 November 2014 0 8K Report

What is the easiest way to check the stoichiometric variations during the sintering process of ultrahigh temperature ceramics such as ZrB2 or TiB2?

How to recognize the final composition of the material (e.g. ZrB2, ZrB1.9 or ZrB2.1)

Badges
Science topic

More Mehdi Shahedi Asl's questions See All

What is the melting point of Al4Si?

The formation of Al4Si intermetallic phase was detected by XRD analysis due to the addition of Al as a sintering aid in an ultrahigh temperature ceramic composite. I want to know the melting...

09 October 2018 7,094 6 View

Minimum temperature needed for the progress of { V + C = VC } reaction?

What is the ignition (minimum required) temperature for the direct synthesis of Vanadium Carbide (VC) using Vanadium and Carbon (Graphite) elements?

31 December 2017 5,411 2 View

Does anyone know about the coefficients of thermal expansion of HCP single crystal ceramics?

Is there any reference for the coefficients of thermal expansion of hexagonal single crystals? Especially, I need to know the probable differences between the coefficients at different directions...

02 March 2015 7,585 3 View

What is the mechanism of thermal etching in ceramics?

I have used the thermal etching method (vacuum atmosphere) for detection of grain boundaries. I would like to know which mechanisms or phenomena can lead to the appearance of grain boundaries? Do...

02 March 2015 8,052 7 View

Can the mismatch in the coefficients of thermal expansion lead to the formation of stress during the sintering?

Can the mismatch in the coefficients of thermal expansion at "a" and "c" directions of a hexagonal structure lead to the formation of stresses at the grain boundaries of poly-crystal ceramics...

02 March 2015 1,469 10 View

What is the nature of chemical bonding of ZrB2?

I need the exact nature of chemical bonding of ZrB2. I think it is mainly covalent, however, is there any reference or an exact database about he percentage of covalent or ionic bondings?

02 March 2015 4,612 12 View

How can I use micro-hardness (Indentation) method to study the kinetics of ceramic matrix composites?

Do you have any references about this topic? I am working on UHTCs (e.g. ZrB2-SiC composites)

08 September 2014 1,571 1 View

Open pores vs. Closed pores?

I have prepared some UHTCs through hot pressing at 1700, 1850 and 2000 °C. Open pores were dominant type of porosity in the samples hot pressed at 1700 °C, but the type changes completely to...

01 February 2014 4,474 5 View

Is it possible to use "Direct Crack Measurement" method for determination of fracture toughness in ceramics that have 25% porosity?

Because of many porosities in the polished surface of a ceramic composite, I'm not able to detect the cracks induced by vickers indenter. Does the Direct Crack Measurement method only work for...

31 December 2013 2,128 3 View

How can I thermally etch a polished surface of an ultrahigh temperature ceramic composite?

What is the best and easiest method for thermally etching of UHTCs? I want to analyze the microstructure, calculate the grain size, and investigate the grain boundaries of a polished sample. Is...

11 December 2013 7,170 15 View

How to define an anisotropic material with asymmetric elastic compliance/stiffness matrix in ANSYS APDL?

I need to model an anisotropic material in which the Poisson's ratio ν_12 ≠ ν_21 and so on. Therefore, the elastic compliance matrix wouldn't be a symmetric one. In ANSYS APDL, for TB,ANEL...

09 August 2024 5,048 2 View

How does grain and grain boundary affect the ceramic when studying its dielectric properties?

I am not able to get good literature and the physics behind how first these grains and grain boundaries arises out of no where when we make a pellet to study its dielectric properties and then how...

07 August 2024 5,177 3 View

RNA later for the preservation of RNA in fecal samples at room temperature for one day (37°C)?

I am planning to collect human fecal samples for metatranscriptomic analysis using MGI. These samples are from indigenous people living in a region with high temperatures. I will have access to a...

06 August 2024 1,367 3 View

How to understand this crystallographic phenomenon of low temperature crystals in zeolite?

During low-temperature testing, new diffraction peaks that appear could be indicative of several phenomena. In one of our tests, we observed notable new peaks around 40° and 45° in a specific...

06 August 2024 726 3 View

Please explain how the plastic input value should be considered from the true stress-strain curve for the bilinear elastoplastic material model ?

I am working on Abaqus/Explicit(Quasistatic ) for the deformation of the auxetic structure model. Please explain how the plastic input value should be considered from the true stress-strain curve...

05 August 2024 454 3 View

Is it possible to improve the reforming section of the Haber-Bosch process without using air separation units?

A typical reforming section in a large-scale Haber-Bosch process (Figure 1) comprises two reactors. A mixture of methane (CH4) and steam (H2O) is fed into a primary reformer to produce syngas via...

01 August 2024 7,051 5 View

How Can I Apply Hashin Damage Properties to Solid Elements in Abaqus Without Using VUMAT?

Sure, here is the translation: I have a 3D orthogonal woven composite structure where warp, weft, and binder yarns are oriented in three directions. After modeling these yarns and the matrix in...

28 July 2024 8,169 0 View

Non -oxidizing metal binders?

I'm trying to sinter some Nb parts and I'm trying to find a binder which does not produce oxidative compounds when it decomposes.

25 July 2024 9,823 3 View

Does it exist some special technique for cutting ceramic membranes for Cross-sectional FESEM images?

Does it exist some special technique for cutting ceramic membranes for Cross-sectional FESEM or SEM images?

25 July 2024 5,482 2 View

How to scrape off the surface layer of compound sputtering targets as with multiple usage top layer's stoichiometry changes from the original target?

I am experiencing this for the Bi2Se3 sputtering target. Initially, even if the target was 2:3 in Bi : Se, with a few sputtering runs, due to the high escaping tendency of selenium, the top layer...

23 July 2024 1,649 1 View