SiC is further a competitive candidate as a first wall material in fusion plasma devices.
A major requirement of NiH structural material is hydrogen containment. SiC will resist hydrogen diffusion out of the NiH reactor through the deployment of a Si surface coat under hydrogen erosion. The SiC surface facing the hydrogen envelope will erode as carbon combines with hydrogen in the chemical reaction SiC + 2H2 => Si + CH4 A coat of Si will face the hydrogen envelope, and that will erode to the gas SiH and SiH4. See http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19900001828.pdf *Hydrogen - Silicon Carbon interaction* This study was done in the temperature range of 1100C to 1400C. A Carbon only material will erode though the CH4 reaction. SiC is a material used for heat exchangers as is carbon. The major advantage of SiC over carbon is it resistants' to hydrogen erosion. Unlike other metallic structural materials like tungsten, SiC is abundant with its major cost component being electrical power to sinter SiC from sand and organic carbon. With the advent of LENR as a electric power producer, that cost component should be drastically reduced. On Wed, Mar 26, 2014 at 10:45 AM, Bob Cook <[email protected]> wrote: > Axil-- > > You said: "My belief is, if it can handle fission of U235, it should > handle LENR." > > U-235 fissioning only depends on being around a thermal neutron. Si-C > would have to maintain its NAE capability when it gets hot. A large range > of operating temperatures for LENR may not be in the cards. Lets hope it > is not, since it would imply that the LENR process would not have a > negative temperature coeff. > > If you are thinking about a dispersion of the NAE within a containment > structure of Si-C then I would agree with you. Plain graphite would > probably work ok also as a containment structure. . > > Bob > > > > ----- Original Message ----- > *From:* Axil Axil <[email protected]> > *To:* vortex-l <[email protected]> > *Sent:* Tuesday, March 25, 2014 11:40 PM > *Subject:* [Vo]:Why not Silicon Carbide for the NiH reactor? > > The high sublimation temperature of SiC (approximately 2700 °C) makes it > at the high end of the insolating ceramic operating temperature range.. > Silicon carbide does not melt at any known pressure. It is also highly > inert chemically. > > Its high thermal conductivity, high electric field breakdown strength and > high maximum current density make it most promising any type of LENR > reaction. > > SiC also has a very low coefficient of thermal expansion (4.0 × 10-6/K) > and experiences no phase transitions that would cause discontinuities in > thermal expansion. > > On the downside, In the 1980s and 1990s, silicon carbide was studied in > several research programs for high-temperature gas turbines in Europe, > Japan and the United States. The components were intended to replace nickel > superalloy turbine blades or nozzle vanes. However, none of these projects > resulted in a production quantity, mainly because of its low impact > resistance and its low fracture toughness. > > Silicon carbide is used in high temperature kilns such as for firing > ceramics, > > Silicon carbide is an important structural material in TRISO-coated fuel > particles, the type of nuclear fuel found in high temperature gas cooled > reactors (such as the Pebble Bed Reactor). A layer of silicon carbide gives > coated fuel particles structural support and is the main diffusion barrier > to the release of fission products. > > My belief is, if it can handle fission of U235, it should handle LENR. > >
