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Questions related from Mehdi Shahedi Asl
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...
10 October 2018 7,040 6 View
What is the ignition (minimum required) temperature for the direct synthesis of Vanadium Carbide (VC) using Vanadium and Carbon (Graphite) elements?
01 January 2018 5,378 2 View
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...
03 March 2015 7,546 3 View
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...
03 March 2015 8,002 7 View
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...
03 March 2015 1,429 10 View
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?
03 March 2015 4,545 12 View
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...
11 November 2014 7,858 0 View
Do you have any references about this topic? I am working on UHTCs (e.g. ZrB2-SiC composites)
09 September 2014 1,525 1 View
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...
02 February 2014 4,406 5 View
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...
01 January 2014 2,086 3 View
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...
12 December 2013 7,129 15 View
I have purchased some ceramic powders (e.g. SiC, BN). The dealer claims that the purity is more than 99 percent. How can I detect and characterize the type of impurities (less than 1 percent) in...
11 November 2013 4,287 6 View
ZrB2-SiC composites sintered by HP. I've tried to measure their hardness by vickers indentor using a load of 2 Kg and a dwell time of 30 s (after polishing), but it's not possible and no...
10 October 2013 9,158 3 View
