31 results about "Reaction bonded silicon carbide" patented technology

A composite body produced by a reactive infiltration process that possesses high mechanical strength, high hardness and high stiffness has applications in such diverse industries as precision equipment and ballistic armor. Specifically, the composite material features a boron carbide filler or reinforcement phase, and a silicon carbide matrix produced by the reactive infiltration of an infiltrant having a silicon component with a porous mass having a carbonaceous component. Potential deleterious reaction of the boron carbide with silicon during infiltration is suppressed by alloying or dissolving boron into the silicon prior to contact of the silicon infiltrant with the boron carbide. In a preferred embodiment of the invention related specifically to armor, good ballistic performance can be advanced by loading the porous mass or preform to be infiltrated to a high degree with one or more hard fillers such as boron carbide, and by limiting the size of the largest particles making up the mass. The instant reaction-bonded silicon carbide (RBSC) composite bodies surpass previous RBSC's as armor materials, and in this capacity approach the ballistic performance of current carbide armor ceramics but with potentially lower cost manufacturing methods, e.g., infiltration techniques.

Metal-ceramic composite materials made by an infiltration technique have now been prepared using microwave energy as the heat source for thermal processing. Specifically, microwave energy has been used to heat and melt a source of silicon metal, which in turn has infiltrated carbon-containing preforms to make reaction-bonded silicon carbide composites, respectively. Both the time-at-temperature as well as the overall thermal cycle time have been greatly reduced, implying a large cost savings.

Ceramic-containing bodies can be bonded to other ceramic-containing bodies, or to metals or metal-containing bodies, by way of an aluminum-silicon brazing alloy. Such alloys feature high thermal conductivity and a melting range intermediate to Cu—Sil and Au—Si. By metallizing the surface of an aluminum- or silicon-containing ceramic body, for example, with silicon or aluminum, the formation of deleterious intermetallic phases at the brazing interface is avoided. This technique is particularly useful for joining reaction-bonded silicon carbide (RBSC) composite bodies, and particularly such composite bodies that contain appreciable amounts of aluminum as a metallurgical modification of the residual silicon phase. Interestingly, when the RBSC body contains minor amounts of the aluminum alloying constituent, or none, the metallization layer is not required. The resulting bonded structures have utility as mirrors, as packaging for electronics, and in semiconductor lithography equipment, e.g., as electrostatic chucks for supporting a silicon wafer during the lithography process.

The invention discloses a method for preparing reaction sintered silicon carbide ceramics. Firstly, waste silicon carbide powder, silicon carbide powder material, adhesive and solvent are added into a ball mill in proportion, and then the mixed powder is put into a drying oven to dry, and then Put the powder into the mold, pressurize it into a blank, then crush the blank, sieve, and then evenly distribute the sifted powder in the cavity of the mold, mold it again into a green body, and heat up and dry it after debinding , place the green body in a graphite crucible, add metal silicon into the crucible, put the crucible into a high-temperature vacuum sintering furnace for sintering, and then lower the temperature to obtain a reaction-sintered silicon carbide ceramic. The invention has a simple process and is suitable for large-scale industrial production, and can not only effectively solve the problems of environmental pollution and resource waste caused by a large amount of silicon carbide waste, but also reduce the raw material price of reaction sintered silicon carbide materials.

Disclosed is a process for producing a RBSiC member that has a large size and a complicated shape and possesses ceramic properties. The process is Selective Laser Sintering process which includes providing a raw material containing silicon carbide particles and a binder, forming a thin layer of the raw material, and sintering the thin layer by irradiating a desired area in the thin layer with laser to form a sintered thin layer, repeating the step of forming the sintered thin layer to obtain a green body, impregnating the green body with a carbon source and curing the green body impregnated with the carbon source to give a cured body, carbonizing an organic compound component in the cured body to give a fired body, and infiltrating the fired body with silicon and subjecting the fired body to reaction sintering to give a RBSiC member, wherein the fired body contains 8% to 30% by weight of carbon.

Techniques to bond two or more smaller bodies or subunits to produce a unitary SiC composite structure extend the capabilities of reaction-bonded silicon carbide, for example, by making possible the fabrication of complex shapes. In a first aspect of the present invention, two or more preforms are bonded together with a binder material that imparts at least strength sufficient for handling during subsequent thermal processing. In a second aspect of the present invention, instead of providing the subunits to be bonded in the form of preforms, the subunits may be dense, SiC composite bodies, e.g., RBSC bodies. In each of the above embodiments, a preferable means for bonding two or more subunits combines aspects of adhesive and mechanical locking characteristics. One way to accomplish this objective is to incorporate a mechanical locking feature to the joining means, e.g., a “keyway” feature. The mechanical locking feature thus substitutes for, or supplements the binder qualities of the adhesive, which is especially important when the adhesive itself may be or become weak due to, for example, thermal processing.

The invention provides a preparation method of reaction-bonded silicon carbide. A monomer, a crosslinking agent dispersant and a raw material are mixed in a ball milling mode, silicon carbide/ carbon black water-based suspensoid of a high solid-phase content and low adhesion is obtained, a green body is formed through a gel injection molding process, and the silicon carbide is obtained after a high-temperature reaction. By means of the preparation method, the silicon carbide in a complex shape can be prepared, sintering time is short, and the preparation method is suitable for preparing large-size silicon carbide products and low in cost.

A process for producing reaction bonded silicon carbide (RBSC) from high purity, porous, essentially all-carbon preforms through contacting said preforms with silicon metal at room temperature, and subsequently heating to melt silicon metal and cause infiltration into said preform causing reaction to silicon carbide and leaving residual silicon, to result in a dense silicon carbide-silicon composite. The process offers the ability to produce RBSC with higher purity, higher strength, and lower cost as long as the carbonaceous preforms are of sufficient purity and pore size distribution to allow for uniform, crack-free bulk bodies to be fabricated.

The invention relates to a binder for binding RBSC (reaction-bonded silicon carbide), which is used to prepare RBSC assembly, wherein it includes a sintered body obtained by sintering a mixed powder of at least one substance selected from the group having Al, Ti, Fe, Mg, Cu and Ge, and silicon, or a powder obtained by milling the sintered body; and with regard to the mixing ratio of the mixed powder, the maximum amount of silicon is an amount rendering the complete melting temperature of phase in phase diagram of the mixed powder to be at most 1400° C., and the minimum amount of silicon is a larger value of either 50 at % or the minimum amount of silicon in silicon+liquid phase zone of the phase diagram, and a method of binding RBSC using the same.

The invention relates to a fluid dynamic pressure type mechanical sealing face structure. Twelve grooves are formed in a sealing end face of a stationary ring, and a regular dodecagon can be formed by connecting the twelve grooves. The grooves are in mutual communication. The connection position of any two adjacent grooves communicates with the outer circumferential surface of the stationary ring. A rotating ring rotates along with a shaft connected with the rotating ring to produce a centrifugal effect, fluid in the grooves is driven to rotate, and therefore a liquid membrane is formed between a sealing end face of the rotating ring and the sealing end face of the stationary ring. The stationary ring and the rotating ring are made from a silicon carbide-graphite composite material, and machined with the reaction bonded silicon carbide and carbon technology. The fluid dynamic pressure type mechanical sealing face structure is suitable for a nuclear main pump, and a good sealing function in a high pressure and radioactivity working environment is achieved.

Disclosed are segmented silicon carbide liners, particularly segmented silicon carbide liners for use in fluidized bed reactors for the production of polysilicon-coated granular materials, and methods of making and using said segmented silicon carbide liners . A non-contaminating adhesive material for joining the silicon carbide segments is also disclosed. One or more of the silicon carbide segments may be constructed from reaction bonded silicon carbide.

Segmented silicon carbide liners for use in a fluidized bed reactor for production of polysilicon-coated granulate material are disclosed, as well as methods of making and using the segmented silicon carbide liners. Non-contaminating bonding materials for joining silicon carbide segments also are disclosed. One or more of the silicon carbide segments may be constructed of reaction-bonded silicon carbide.

The invention relates to high-purity silicon to form silicon carbide for use in fluidized bed reactor. Segmented silicon carbide liners, in particular, segmented silicon carbide liners for use in a fluidized bed reactor for production of polysilicon-coated granulate material are also disclosed, as well as methods of making and using the segmented silicon carbide liners. Non-contaminating bonding materials for joining silicon carbide segments also are disclosed. One or more of the silicon carbide segments may be constructed of reaction-bonded silicon carbide.