It is only possible with diamond wheels with water cooling.

You can cut SiC or B4C carbide plates by Electrical Discharge Machining (EDM):

http://www.automationmag.com/images/stories/LWTech-files/91%20Electrical%20Discharge.pdf

Dr. Verlotski and Dr. Queiroz, thanks a lot for your thoughts!

I am also facing this problem to cut SiC. I have 4H, 6H and 3C- SiC, 2'' and 4'' dia, 400 microns thick wafers. The way of cutting is by using ADT dicing machine with diamond wheel cutter. But still also I have some problem.

Do it easy with diamond disks and continuous cooling by any liquids at a dedicated milling station...

Currently, there are enough appropriate equipment to solve this technical problem.

I recently cut sintered using a diamond disk with runnig water. The SiC was 100mm by 100mm in cross-section. It took about 15-20 minutes.

you can cut silicon carbide by grinding machine with diamond wheel cutter as i have cut. you can also use wire EDM but there are lot of things to care. you can see this article.

Chapter Experimental Study on Improving Material Removal Rate and Su...

Another option is using a waterjet laser. We can cut nearly any kind of freeform shape in Silicon Carbide and Boron Carbide. Thickness of 8mm we have done and depending on the size of the part to cut out it takes just a few minutes. You can see some examples here: http://www.avonisys.com/sic-silicon-carbide-laser-processing-cutting-drilling.html

I tried to cut it by diamond wire, but the wire lost its sharpness after one cut.

A diamond disk cooled by liquids is much better for this task...!

As these materials are among the hardest known, you have to use a diamond saw blade, at best with a metal bonding (e.g. bronze)

I preffer to cut B4C and SiC composites by EDM.. You need to polish surface liitle bit to remove heat affected zone