Methods for preparing ceramic matrix composites using melt infiltration and chemical vapor infiltration are provided as well as the resulting ceramic matrix composites. The methods and products include the incorporation of sacrificial fibers to provide improved infiltration of the fluid infiltrant. The sacrificial fibers are removed, such as decomposed during pyrolysis, resulting in the formation of regular and elongate channels throughout the ceramic matrix composite. Infiltration of the fluid infiltrant can then take place using the elongate channels resulting in improved density and an improved ceramic matrix composite product.

This invention relates to three-dimensional printing. This invention in particularly relates to a system for drying a paste-based crafting medium during three-dimensional printing and a method thereof. The system can comprise a dual printhead comprising a first dispensing nozzle for depositing the filament material for a mold layer in a flowable fluid form and a second dispensing nozzle for depositing the crafting medium, which is in a paste form. The system also includes a drying means which can be a heating system or a drying apparatus, that in some embodiments can be attached to the printhead. The three-dimensional imaging process for making objects, preferably metal objects or ceramic objects, on a layer-by-layer basis under the control of a data processing system is disclosed. The drying of the object or mold is crucial in the three-dimensional imaging process because it can affect the overall quality of the object. A solution to this problem is achieved in the present invention by using a drying step after finishing each layer of the object (both mold and paste). This is achieved in some embodiments by using a drying apparatus comprising a radiating heater and air circulation fan mounted on to the moving print head. The print head can repeatedly scan the printed layer and apply heat and air circulation to improve drying in a controlled manner. This system and method provides improved evenness in the drying and reduces the risk of cracks developing in the deposited object, and also reduces the risk of further problems during the subsequent processing steps to provide the finished object.

This invention relates to three-dimensional printing. This invention in particularly relates to a method of fabricating a three-dimensional object using a support edifice and also using a mold material with structural additives. The support edifice is fabricated in the same crafting material as the final three-dimensional object in the same manner as the printing of the final three-dimensional object (mold and crafting in a layer by layer manner). This method enables the support edifice to also transform during post processing in the same manner as the final three-dimensional object, thus supporting the object until finished. The system for fabricating the object comprises a dual printhead comprising a first dispensing nozzle for depositing the filament material in a flowable fluid form and a second dispensing nozzle for depositing the crafting medium, which is in a paste form. The printhead can also include a heating system or a drying apparatus. The three-dimensional imaging process for making objects, preferably metal objects or ceramic objects, on a layer-by-layer basis under the control of a data processing system is disclosed. The printing of the three-dimensional object such as heavy objects or an object having different parts having a very thin gap or space. It is important to use different processing steps and/or material to print such three-dimensional objects. The present invention provides a solution by printing a support edifice comprising a special structural additive for the mold, and further the support edifice can be printed simultaneously while printing the mold and crafting-paste material on a layer-by-layer basis. The mold material is mixed with the structural additive. The structural additive is useful for prohibiting either fusing of the object with the support edifice, or in alternative embodiments, the fusing of one part of an object with another part of an object.

A composite composed of two principal strengthening compounds and one principal cementing refractory metal that is prepared by combining a suitable binary to senary borides and/or carbides with a unitary to binary principal refractory metal is disclosed. As compared with the conventional sintered cemented carbides, the composite of the disclosure not only possess high hardness and high toughness but also has various ratios of principal components since it is not prepared with equal mole during the process.

Methods for preparing ceramic matrix composites using melt infiltration and chemical vapor infiltration are provided as well as the resulting ceramic matrix composites. The methods and products include the incorporation of sacrificial fibers to provide improved infiltration of the fluid infiltrant. The sacrificial fibers are removed, such as decomposed during pyrolysis, resulting in the formation of regular and elongate channels throughout the ceramic matrix composite. Infiltration of the fluid infiltrant can then take place using the elongate channels resulting in improved density and an improved ceramic matrix composite product.

According to some embodiments, a system includes a three-dimensional (3D) printer, a hydraulic press, and a kiln. The three-dimensional printer includes a print bed, a first printhead, and a second printhead. The first printhead is configured to deposit a layer of a first powder on the print bed. The second printhead is configured to deposit a layer of a second powder on the print bed. The hydraulic press is configured to compress a greenware to form a compressed greenware. The kiln is configured to heat the compressed greenware to a reaction temperature to form an object. The object is surrounded by an excess of the first powder. The kiln is also configured to heat the object surrounded by the excess of the first powder to a melting temperature. The melting temperature is at least the melting point of the first powder and less than the melting point of the object.

A sintered material includes a first material and a second material, wherein the first material is partially stabilized ZrO.sub.2 in which 1 to 90 volume % of Al.sub.2O.sub.3 is dispersed in crystal grain boundaries or crystal grains, the Al.sub.2O.sub.3 is a grain having a grain size of less than or equal to 1 m, and the second material is at least one compound selected from a group consisting of a carbide, a nitride, and a carbonitride, and 5 to 95 volume % of the second material is included in the sintered material.

A method for synthesizing high-purity ultrafine ZrCSiC composite powder is provided. The high-purity ultrafine ZrCSiC composite powder is prepared by utilizing zirconium silicate only or zirconium silicate with one or both of zirconium oxide or silica sol as a zirconium source and a silicon source material, utilizing sucrose or glucose as a carbon source material, and utilizing acrylamide monomer and N,N-methylene diacrylamide cross-linking agent as a gel material.

A method for preparing a ceramic-modified carbon-carbon composite material. The method includes preparing and thermally treating a carbon fiber preform, and depositing pyrolytic carbon on the carbon fiber preform in a chemical vapor infiltration furnace, to yield a porous carbon-carbon composite material; placing the carbon-carbon composite material deposited with the pyrolytic carbon on a zirconium-titanium powder mixture, and performing a reactive melt infiltration, to yield a carbon-carbon composite material modified by non-stoichiometric zirconium titanium carbide; and placing the carbon-carbon composite material modified by non-stoichiometric zirconium titanium carbide in a powder mixture including carbon, boron carbide, silicon carbide, silicon, and an infiltration enhancer, and performing an embedding method, to form a ceramic-modified carbon-carbon composite material.

Disclosed are compositions containing nanoparticles of a metal nitride, boride, silicide, or carbide, a filler material, and a carbonaceous matrix. The precursor to this material contains nanoparticles or particles of boron, silicon, iron, a refractory metal, or a refractory metal hydride, an organic compound having carbon and hydrogen, and a filler material. Multilayered materials are also disclosed.