The present invention discloses a high-strength prestressed composite ceramic and a preparation method thereof, and belongs to a ceramic reinforcing technology in the field of high-performance structural ceramics. Firstly, more than two kinds of bondable ceramics need to be determined to form a composite ceramic of a matrix material and a surface layer material, the matrix material should have sufficient strength and a higher expansion coefficient, and the surface layer material should have a lower expansion coefficient and a higher elastic modulus, realizing the balance of the surface layer compressive stress and the matrix tensile stress are formed after high-temperature co-sintering; and the surface layer compressive stress can greatly improve the bending strength of the composite ceramic. The magnitude of the compressive stress can be adjusted by optimizing the section ratio of the two materials of the cross sections, the surface prestress is designed to be more than the strength value of the surface layer material for the given two materials, and the section ratio is determined through deduction and calculation of a prestress calculation formula. The composite ceramic with prestress can be obtained after sintering greatly improving the strength. The present invention solves the current problem of difficulty in improving the strength of structural ceramics and has good practical value.

A method of altering a surface of a ceramic matrix composite to aid in nodule removal is described. A fiber preform comprising a framework of ceramic fibers is heated to a temperature at or above a melting temperature of silicon. During the heating, the fiber preform is infiltrated with a molten material comprising silicon. After the infiltration, the fiber preform is cooled, and the infiltrated fiber preform is exposed to a gas comprising nitrogen during cooling. Silicon nitride may be formed by a reaction of free (unreacted) silicon at or near the surface of the infiltrated fiber preform with the nitrogen. Thus, a ceramic matrix composite having a surface configured for easy nodule removal is formed. Any silicon nodules formed on the surface during cooling may be removed without machining or heat treatment.

A method of making a plurality of composite granules can include: forming green body granules comprising an aluminosilicate; heating the green body granules to form sintered granules; cooling the sintered granules according to a cooling regime, wherein the cooling regime comprises a temperature hold between 700 C. and 900 C. for at least one hour. In a particular embodiment, the aluminosilicate for making the composite granules can have a particle size less than 150 m. The composite granules are particularly suitable as roofing granules and can have a desired combination of high solar reflectance SR and low lightness L*, a low bulk density, good weather resistance and strength.

A method of making a plurality of composite granules can include: forming green body granules comprising an aluminosilicate; heating the green body granules to form sintered granules; cooling the sintered granules according to a cooling regime, wherein the cooling regime comprises a temperature hold between 700 C. and 900 C. for at least one hour. In a particular embodiment, the aluminosilicate for making the composite granules can have a particle size less than 150 m. The composite granules are particularly suitable as roofing granules and can have a desired combination of high solar reflectance SR and low lightness L*, a low bulk density, good weather resistance and strength.

A ceramic coating includes: a ceramic layer; a molten-and-solidified layer formed on a surface of the ceramic layer; and a packed layer including ceramic packed in a crack which extends in a thickness direction of the molten-and-solidified layer.

A method for manufacturing a solid-state electrolyte for a battery cell, wherein a ceramic green body is provided, wherein the green body is sintered to form a solid-state electrolyte material, and wherein after the sintering, the solid-state electrolyte material is coated on the electrode side with a protective layer made of polytetrafluoroethylene, and is subsequently cooled.

A method for manufacturing a solid-state electrolyte for a battery cell, wherein a ceramic green body is provided, wherein the green body is sintered to form a solid-state electrolyte material, and wherein after the sintering, the solid-state electrolyte material is coated on the electrode side with a protective layer made of polytetrafluoroethylene, and is subsequently cooled.

A hot-pressed geopolymeric composition and producing method for making the ultra-high strength geopolymer are disclosed. The hot-pressed geopolymeric composition may include at least one aluminosilicate source and at least one alkali activator and optionally any kind of fillers. The ultra-high strength geopolymer with various densities can be produced by applying low hot-pressing pressure in a short time.

A method of making a plurality of composite granules can include: forming green body granules comprising an aluminosilicate; heating the green body granules to form sintered granules; cooling the sintered granules according to a cooling regime, wherein the cooling regime comprises a temperature hold between 700 C. and 900 C. for at least one hour. In a particular embodiment, the aluminosilicate for making the composite granules can have a particle size less than 150 m. The composite granules are particularly suitable as roofing granules and can have a desired combination of high solar reflectance SR and low lightness L*, a low bulk density, good weather resistance and strength.

A sintered ceramic body comprising at least one layer comprising from 90% to 99.8% by volume of polycrystalline yttrium aluminum garnet (YAG) and from 15 ppm to 500 ppm of zirconium, wherein the at least one layer comprises at least one surface, wherein the at least one surface comprises pores having a pore size not exceeding 5 pm and having a maximum pore size of 1.5 pm for at least 95% of the pores, wherein the at least one surface exhibits an L* value of from 50 to 77, and an a value of from 6 to 12, wherein the at least one layer has a thickness of from 500 pm to 2 cm, and wherein the values of L* and a vary no more than 10% across the at least one surface. Also disclosed are methods of making same.