An alumina/titanium silicon carbide composite material is prepared by making titanium aluminum carbide (Ti.sub.3AlC.sub.2) in uniform contact with silicon monoxide (SiO), and carrying out vacuum sintering. The composite material is obtained through mutual diffusion of aluminum and silicon and has high compactness and stable performance. In the composite material, the alumina is generated by means of a reaction between the titanium aluminum carbide and the silicon monoxide, and can be uniformly wrapped around surfaces of titanium silicon carbide crystals to form a relatively compact oxide film, such that substance exchange between a matrix and the outside is hindered, and overall antioxidation of the composite material is improved. Toughness of the composite material is enhanced by means of the titanium silicon carbide. The prepared composite material has relatively high purity, relatively low sintering temperature, and relatively high bending strength. The process is simple and convenient for industrial production.

A cubic boron nitride sintered body including cubic boron nitride and a binder phase, wherein a content of the cubic boron nitride is 40 volume % or more and 80 volume % or less; a content of the binder phase is 20 volume % or more and 60 volume % or less; an average particle size of the cubic boron nitride is 0.5 μm or more and 4.0 μm or less; the binder phase contains TiC and TiB.sub.2 and contains substantially no AlN and/or Al.sub.2O.sub.3; a (101) plane of TiB.sub.2 in the binder phase shows a maximum peak position (2θ) in X-ray diffraction of 44.2° or more; and a (200) plane of TiC in the binder phase shows a maximum peak position (2θ) in X-ray diffraction of less than 42.1°.

The present disclosure provides a boron carbide composite material having a novel composition with excellent mechanical properties, and a production method therefor. The boron carbide composite material has high fracture toughness and may be applied as a lightweight bulletproof ceramic material. The boron carbide composite material is a boron carbide/silicon carbide/titanium boride/graphite (B.sub.4C—SiC—TiB.sub.2—C) composite material. The composite material may overcome a technical limitation on increasing the fracture toughness of the boron carbide composite material, and may be produced as a high-density boron carbide composite material using a reactive hot-pressing sintering process at a relatively low temperature. The boron carbide composite material having excellent mechanical properties may be applied to general industrial wear-resistant parts and nuclear-power-related industrial parts, and particularly, may be actively used as a lightweight bulletproof material for personal use and for military aircraft including helicopters.

Compositions comprising preceramic resins and fumed alumina are described. The compositions can also include fillers, such as silicon carbide whiskers or zirconium diboride particles. The compositions can be used as three-dimensional printable inks for preparing ceramic composites, e.g., composites having complex geometry. Inclusion of fumed alumina as a rheology modifier in the composition can provide improved printing properties for the inks compared to preceramic resin inks that do not include fumed alumina.

A composite precursor powder, including one or more metals or metalloids, and one or more oxides, wherein a molar ratio of the one or more metals or metalloids to the one or more oxides is from about 1:0.01 to about 1:4, and wherein the molar ratio of the one or more metals or metalloids to the one or more oxides is configured according to a desired volumetric change of the composite precursor powder when converted to a non-oxide ceramic.

A cBN sinter comprising cubic boron nitride grains and a binder phase, the binder phase comprising Ti.sub.2CN and Co.sub.2B, wherein the ratio I.sub.Ti2CN/I.sub.Co2B of a peak intensity I.sub.Ti2CN assigned to Ti.sub.2CN appearing at 2θ = 41.9° to 42.2° to a peak intensity I.sub.TiAl3 assigned to Co.sub.2B appearing at 2θ = 45.7° to 45.9° is in a range of 0.5 and 2.0 in an XRD measurement.

Polycrystalline cubic boron nitride compact include a body having sintered microcrystalline cubic boron nitride in a matrix of binder material. The microcrystalline cubic boron nitride particles have a size ranging from 2 microns to 50 microns. The particles of microcrystalline cubic boron nitride include a plurality of sub-grains, each sub-grain having a size ranging from 0.1 micron to 2 microns. The compacts are manufactured in a high pressure—high temperature (HPHT) sintering process. The compacts exhibit intergranular defect formation following introduction of wear. The sub-grains promote crack propagation based on micro-chipping rather than on a cleavage mechanism and, in sintered bodies, cracks propagate intergranularly rather than intragranularly, resulting in increased toughness and improved wear characteristics as compared to monocrystalline cubic boron nitride. The compacts are suitable for use as abrasive tools.

A surface-coated boron nitride sintered body tool is provided, in which at least a cutting edge portion includes a cubic boron nitride sintered body and a coating film formed on a surface of the cubic boron nitride sintered body. The coating film includes an A layer and a B layer. The A layer is formed of columnar crystals each having a particle size of 10 nm or more and 400 nm or less. The B layer is formed of columnar crystals each having a particle size of 5 nm or more and 70 nm or less. The B layer is formed by alternately stacking two or more compound layers having different compositions. The compound layers each have a thickness of 0.5 nm or more and 300 nm or less.

A cermet contains hard phase particles containing Ti and a binding phase containing at least one of Ni and Co, and 70% or more (by number) of the hard phase particles have a cored structure containing a core and a peripheral portion around the core. The core is composed mainly of at least one of Ti carbide, Ti nitride, and Ti carbonitride, and the peripheral portion is composed mainly of a Ti composite compound containing Ti and at least one selected from W, Mo, Ta, Nb, and Cr. The core has an average particle size α, the peripheral portion has an average particle size β, and α and β satisfy 1.1≦β/α≦1.7.

The present invention discloses a nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet and a preparation method and application thereof. Ti.sub.3C.sub.2-MXene is obtained by etching ternary layered carbides of MAX phase through hydrofluoric acid; and then, the nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet is synthesized by a simple one-step method by taking thiourea as a heteroatom source. The nitrogen-sulfur co-doped Ti.sub.3C.sub.2-MXene nanosheet has a unique two-dimensional layered structure, large specific surface area and abundant heteroatomic catalytic activity sites so that the material presents excellent peroxidase-like activity. The method of the present invention can successfully dope two elements of nitrogen and sulfur in one step on Ti.sub.3C.sub.2-MXene, and can effectively overcome the tedious problem of a step-by-step doping step and the secondary pollution problem of different doping sources to endow peroxidase-like activity for Ti.sub.3C.sub.2-MXene.