Where [Hiro’s] body has bony extremities, the suit has sintered armorgel: feels like gritty jello, protects like a stack of telephone booths
So, sintered means this:
To form a material from fusible powder by holding the pressed powder at a temperature just below its melting point for a period of time; the particles are fused (sintered) together, but the mass, as a whole, does not melt.
Now, Technovelgy has an entry on sintered armorgel, and reckons that what Stephenson is describing is a dilatant fluid.
Thanks to the wonders of the intertubes, you can see what a dilatant fluid does right here:
May 26th, 2007 | dilatant, sinteredamorgel, deliverator, p1 | No comments