Abstract: A moldable green-body composite includes milling silicon nitride powder with a solvent and adding a surface modifier to the milled slurry to modify a surface of the silicon nitride particles. A polysiloxane in a solvent and a binder are also added to create a green body slurry. The solvents may be polar or non-polar solvents. A sintering aid, such as yttria-alumina, may be added to the slurry as well. A reduced density silicon nitride ceramic is made from the moldable green-body composite by molding the moldable green-body composite in a mold and curing at a curing temperature to convert the moldable green-body composite to a converted composite. The converted composite can then be sintered to form a reduced density silicon nitride ceramic that has a smooth surface finish and requires no post machining or polishing. The reduced density silicon nitride ceramic may also have very good dielectric properties.

Abstract: A moldable green-body composite includes milling silicon nitride powder with a solvent and adding a surface modifier to the milled slurry to modify a surface of the silicon nitride particles. A polysiloxane in a solvent and a binder are also added to create a green body slurry. The solvents may be polar or non-polar solvents. A sintering aid, such as yttria-alumina, may be added to the slurry as well. A reduced density silicon nitride ceramic is made from the moldable green-body composite by molding the moldable green-body composite in a mold and curing at a curing temperature to convert the moldable green-body composite to a converted composite. The converted composite can then be sintered to form a reduced density silicon nitride ceramic that has a smooth surface finish and requires no post machining or polishing. The reduced density silicon nitride ceramic may also have very good dielectric properties.

Abstract: A tri-band multiwall radome includes a dense polymeric strike plate that is configured on the outside of the radome, a capture layer and a tuning layer. The polymeric strike plate is a tough polymer, such as a polycarbonate and breaks a bullet into fragments that are more easily captured by the capture layer. The capture layer includes a number of fabric sheets of highly oriented fibers, such as polyethylene fibers, and a binder. The tuning layer may be a low density foam that is configured inside of the capture layer and provided to reduce reflective losses and improve ballistic performance. A tri-band radome cover may have a dB loss over a wavelength of 8 to 40 kHz of no more than 1 dB. A tri-band radome cover may be formed in a dome shape.

Abstract: A tri-band multiwall radome includes a dense polymeric strike plate that is configured on the outside of the radome, a capture layer and a tuning layer. The polymeric strike plate is a tough polymer, such as a polycarbonate and breaks a bullet into fragments that are more easily captured by the capture layer. The capture layer includes a number of fabric sheets of highly oriented fibers, such as polyethylene fibers, and a binder. The tuning layer may be a low density foam that is configured inside of the capture layer and provided to reduce reflective losses and improve ballistic performance. A tri-band radome cover may have a dB loss over a wavelength of 8 to 40 kHz of no more than 1 dB. A tri-band radome cover may be formed in a dome shape.

Abstract: A tri-band multiwell radome includes a dense polymeric strike plate that is configured on the outside of the radome, a capture layer and a tuning layer. The polymeric strike plate is a tough polymer, such as a polycarbonate and breaks a bullet into fragments that are more easily captured by the capture layer. The capture layer includes a number of fabric sheets of highly oriented fibers, such as polyethylene fibers, and a binder. The tuning layer may be a low density foam that is configured inside of the capture layer and provided to reduce reflective losses and improve ballistic performance. A tri-band radome cover may have a dB loss over a wavelength of 8 to 40 kHz of no more than 1 dB. A tri-band radome cover may be formed in a dome shape.

Abstract: A tri-band multiwell radome includes a dense polymeric strike plate that is configured on the outside of the radome, a capture layer and a tuning layer. The polymeric strike plate is a tough polymer, such as a polycarbonate and breaks a bullet into fragments that are more easily captured by the capture layer. The capture layer includes a number of fabric sheets of highly oriented fibers, such as polyethylene fibers, and a binder. The tuning layer may be a low density foam that is configured inside of the capture layer and provided to reduce reflective losses and improve ballistic performance. A tri-band radome cover may have a dB loss over a wavelength of 8 to 40 kHz of no more than 1 dB. A tri-band radome cover may be formed in a dome shape.

Abstract: An aquarium system consist of an open topped fish tank, a base cabinet stand and an encased cover, wherein unclarified aquarium water is drawn downwards by gravity and filtered below the tank, while being aerated and heated as it is returned to the tank in a waterfall fashion.The tank includes removable gravel support grating trays, a funnelform bottom and a drain.The stand houses a main shut-off valve, a clean out trap, a filter tank with a removable cap and fiber housing, along with a holding tank and water pump.The cover encasement houses a light, an aerator, a water compartment and guide tray, as well as a programmable timer to control the on/off functions of the water pump.In operation, unclarified water in the tank is drawn downwards by gravity and is filtered once as it passes into the drain, and again in the filter tank, before being pumped into the water compartment.