American Matrix, Inc.

Industrial Ceramic Solutions

Other

Industrial Ceramics Solutions

America Matrix, Inc.

Richard D Nixdorf

Samuel C Weaver

Mary H Rawlins

A filter medium formed from a web of ceramic fibers, pleated and integrated into a coherent unit employing a ceramic sol. A method is disclosed.

Ceramic fiber-based filter web and method

A filtration system () operable at elevated temperatures and regenerateable in situ employing microwave energy (). In one embodiment, the system includes multiple channels () with means for selectively placing individual ones of the channels on-line for filtration and off-line for regeneration.

Filter system employing microwave regeneration

Method for producing discontinuous silicon carbide fibers, useful as heating elements in a low-energy microwave field, from discontinuous carbonized cotton fibers employing an admixture of carbonized cotton fibers, a metal salt promoter, calcium oxalate monohydrate, and low-density silicon dioxide. The admixture, in a dry state, is introduced into a preheated oven at about 1450 to 1750 degrees C. for between about one and five hours. Silicon carbide fibers and a sheet formed from the fibers are disclosed.

Whisker-free silicon carbide fibers

Method and filter apparatus for the removal of volatilizable particulate material from gas streams containing the same, and the regeneration of the apparatus when removal efficiency has decreased to a selected value. The apparatus includes a filter element fabricated, in the preferred embodiment from silicon carbide whiskers which are capable of converting microwave energy to thermal energy, with the porosity of the filter element being about 25 microns.+-.50%. This filter element, when removal efficiency has decreased to the selected value, is heated uniformly with microwave energy, which couples to the silicon carbide whiskers to convert the microwave energy to thermal energy, for a time sufficient to raise the silicon carbide whisker temperature to a value to volatilize the volatilizable particulate matter for discharge as a gas. Typically, the microwave energy is about 2.45 GHz and 1000 to 3000 watts. In the preferred form, the filter element is surrounded with a thermal insulation formed from, for example, alumina or zirconia fibers. This insulation is provided with passageways for cooling using air flow. The apparatus is specifically directed to the removal of carbon-containing particulates from the exhaust of diesel-fueled engines.

Filter and means for regeneration thereof

A method for producing a high yield of free-flowing alpha-phase single crystal silicon carbide platelets. Through the use of various parameter and composition values, the size range of the platelets can be controlled. For example, small size platelets can be prepared by first heating a mixture of finely divided silicon dioxide and carbon to a temperature of about 1600.degree..+-.100.degree. C. for a duration of about 5-10 hours to produce a silicon carbide product, referred to as a 'prefire' product. This prefire product is mixed with a platelet-enhancing material in the form of powdered carbon or aluminum metal (and mixtures thereof) and then further heated to about 1900.degree.-2400.degree. C. for 2-10 hours to make the platelets. Also, small platelets can be made by substituting silicon carbide whiskers for the intermediate prefire material and adding a platelet enhancing material. Large platelets are formed by mixing the prefire product and a platelet-enhancing material of a mixture of powdered aluminum metal and anhydrous boric oxide. This mixture is heated to about 2150.degree..+-.250.degree. C. for 2-10 hours. During any of the heating steps the gaseous products of the reaction are maintained at substantially steady state by flowing an inert gas, e.g., argon, through the furnace.

Method for the preparation of silicon carbide platelets

A process for the manufacture of single crystal titanium nitride whiskers having uniform diameters and lengths suitable for use in the reinforcing of many matrix materials. The process is carried out by rapidly heating a mixture of titanium dioxide, fibrous carbon and a catalyst selected from individual combinations of cobalt, nickel, magnesium and calcium, for example. This mixture of solids is maintained in a closed container and is rapidly heated to a temperature of about 1300.+-.100 degrees C. for about 1 hour. During this heating a halogen, preferably a chlorine-containing gas, in conjunction with nitrogen is passed into the container whereby the titanium dioxide is converted to titanium nitride in the form of single crystal whiskers. These whiskers have a uniform diameter of about 0.5 to about 1 micron and average lengths of about 30-60 microns. The exterior surface is particularly amenable to bonding to the matrix material to which these whiskers are added for strength.

Method for the preparation of titanium nitride whiskers

A method for producing a high temperature, high strength bond between a ceramic shape and a metal substrate, such as joining a ceramic cap to a piston for an internal combustion engine. The composite joint is effected through the use of a ceramic preform fabricated using fibers, whiskers, platelets or sponge-like particles having the same composition as the ceramic body. The preform is joined to the ceramic shape by using a ceramic slip having a ceramic corresponding in composition with the ceramic body, with this juncture being heated to achieve a secure bond. The preform is joined to the metal substrate by first infiltrating the preform with molten material corresponding to the substrate, and then pressure bonding the infiltrated preform to the substrate after the molten material has solidified. The substrate can be metal or metal alloys. An example is given for the bonding of silicon carbide to a 300 series aluminum.

Method of producing a high temperature, high strength bond between a

A method for achieving a high yield of beta silicon carbide whiskers. According to this method, very small (e.g., 0.002 microns) fluffy silicon dioxide particles having a very large surface area (e.g., 200 m.sup.2 /g) are mixed with a fluffy carbonized material. These materials have a void volume of about 40 percent or greater. The silicon dioixde is present in an amount by weight approximately twice that of the carbon constituent. This mixture is heated, preferably in the presence of a catalyst (e.g., anhydrous boric oxide and powdered aluminum metal) at a temperature of about 1650.degree..+-.300.degree. C. for a time of one-half to four hours. During this heating the gaseous reaction products are maintained at a steady state as with a low flow of argon gas through the furnace. The resultant SiC whiskers have a diameter in the range of about 0.5 to 10 micrometers, and a length of about 10 to about 1000 micrometers. These SiC whiskers are principally beta phase silicon carbide and the whiskers have a smooth surface morphology. The effects of the variables are described.

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Knoxville, TN, United States of America

Richard D Nixdorf