“Green”, ceramic tapes intended as building blocks for making complex, fully ceramic components and devices for electronic-, lab-on-chip-, and sensing applications, the manufacture of which comprises in sequence: I. mixing of a ceramic “green” paste, II. homogenisation of a ceramic “green” paste, III. dimensioning and optionally structuring the ceramic “green” paste, IV. drying of the dimensioned and structured ceramic paste, in which: step iii) is performed in a combination of an extruder and a calender, the extruder being provided with a circular extrusion die, splitting and unfolding the extruded tube to a flat, continuous tape strip, using methylcellulose or derivatives thereof as binder, and, an additional step chosen among cutting and punching the thus dimensioned and optionally structured “green” paste, thereby making thick, “green” tapes. A method for its manufacture is also contemplated.

A ceramic substrate and a method for production thereof are provided, in which the ceramic substrate includes a composite of : a first ceramic layer including Sr anorthite and Al.sub.2O.sub.3 or an oxide dielectric with a dielectric constant higher than that of Al.sub.2O.sub.3; and a second ceramic layer including Sr anorthite and cordierite and having a dielectric constant lower than that of the first ceramic layer.

The present invention provides for materials and methods of making metal and ceramic matrix composites reinforced with boron nitride nanomaterials for improved physical properties such as hardness, fracture toughness, and bend strength.

Shaped ceramic abrasive particles include a first surface having a perimeter having a perimeter comprising at least first and second edges. A first region of the perimeter includes the second edge and extends inwardly and terminates at two corners defining first and second acute interior angles. The perimeter has at most four corners that define acute interior angles. A second surface is disposed opposite, and not contacting, the first surface. A peripheral surface is disposed between and connects the first and second surfaces. The peripheral surface has a first predetermined shape. Methods of making the shaped ceramic abrasive particles, and abrasive articles including them are also disclosed.

Particles of a refractory metal or a refractory-metal compound capable of decomposing or reacting into refractory-metal nanoparticles, elemental silicon, and an organic compound having a char yield of at least 60% by weight are combined to form a precursor mixture. The mixture is heating, forming a thermoset and/or metal nanoparticles. Further heating form a composition having nanoparticles of a refractory-metal silicide and a carbonaceous matrix. The composition is not in the form of a powder

A refractory, coarse ceramic product including at least one granular refractory material, has an open porosity of between 22 and 45 vol.-%, in particular of between 23 and 29 vol.-%, and a grain structure of the refractory material, wherein the medium grain size fraction with grain sizes of between 0.1 and 0.5 mm is 10 to 55 wt.-%, in particular 35 to 50 wt.-%, and wherein the remainder of the grain structure is a finest grain fraction with grain sizes of up to 0.1 mm and/or coarse-grain fraction with grain sizes of more than 0.5 mm.

A composite ceramic composition including a boron carbide phase and a method of forming the same. The composite ceramic composition includes a tungsten boride phase, a transition metal boride phase. The composite ceramic composition may also include a carbon disposed in solid solution with at least the tungsten boride phase and the transition metal boride phase. The transition metal boride phase may include a boride of at least one metal chosen from Cr, Nb, and Zr.

The present invention is related to the development of a new formulation of electrical grade porcelain having improved mechanical and dielectric characteristics, and whose primary application is in electrical components, such as electric insulators.

This invention has as its main object to provide a new alternative to increase the final properties of an electrical grade porcelain, which is related to the incorporation of suitable concentrations of nanosized ceramic oxides, as part of the initial composition of porcelain paste.

This new nanotechnology alternative favors an increase in the final properties of electrical grade porcelain, such as flexural strength or cold rupture modulus, as well as dielectric strength, which is due to the incorporation of ceramic oxides such as alumina (α-Al.sub.2O.sub.3) and zirconia (ZrO.sub.2), in micrometer scale (i.e., less than 100 nanometers), favorably modify the microstructure of the base porcelain.

Mechanical strength, specifically the flexural strength at three points, of the porcelain compositions of the present invention is up to 38% greater than a silica based conventional porcelain composition. Furthermore, the insulating ability of the composition of this invention is up to 30% above the value of the reference siliceous porcelain.

Another important aspect of this invention is based on the concept that the ceramic nano-oxides of (α-Al.sub.2O.sub.3) and zirconia (ZrO.sub.2) strengthen the microstructure of siliceous porcelain, since the amount of crystalline phase increases and therefore the amorphous phase is reduced. Furthermore, the ceramic nano-oxides favor the increase in the concentration of the crystalline mullite phase (3Al.sub.2O.sub.3.2Si0.sub.2) in the microstructure, which is known to benefit the mechanical performance of triaxial porcelains.

Provided herein are methods for making a freeze-cast material having a internal structure, the methods comprising steps of: determining the internal structure of the material, the internal structure having a plurality of pores, wherein: each of the plurality of pores has directionality; and the step of determining comprises: selecting a temperature gradient and a freezing front velocity to obtain the determined internal structure based on the selected temperature gradient and the selected freezing front velocity; directionally freezing a liquid formulation to form a frozen solid, the step of directionally freezing comprising: controlling the temperature gradient and the freezing front velocity to match the selected temperature gradient and the selected freezing front velocity during directionally freezing; wherein the liquid formulation comprises at least one solvent and at least one dispersed species; and subliming the at least one solvent out of the frozen solid to form the material.

[Problem]

To provide a zirconia mill blank for dental cutting and machining which may impart reproducibility of color tone similar to a natural tooth and high strength to a zirconia perfect sintered body without a special sintering method such as HIP treatment.

[Solution]

A zirconia mill blank for dental cutting and machining comprises at least two intermediate layers LA and LB which satisfy the following Formula (1) and Formula (2), wherein the layer LA is contained in a section A in which a distance from one plane of two planes is within 40% of the distance between the two planes and the layer LB is contained in a section B in which a distance from the other plane is within 40% of the distance between the two planes, wherein in a case in which, a sintered body prepared by sintering at 1550° C. a test specimen cut out from the layer LA is defined as sintered body SA, a sintered body at 1550° C. prepared by sintering a test specimen cut out from the layer LB is defined as sintered body SB, a contrast ratio of the sintered body SA at a sample having a thickness of 1 mm is defined as contrast ratio CA and a contrast ratio of the sintered body SB at a sample having a thickness of 1 mm is defined as contrast ratio CB, the contrast ratios CA and CB satisfy the following Formula (3), change directions of yttria concentration, alumina concentration and contrast ratio in a stacking direction are not changed by the at least two intermediate layers.

Yttria concentration of layer LA−Yttria concentration of layer LB>1.0 mol %  Formula (1):

0.0 wt. %<Alumina concentration of layer LB−Alumina concentration of layer LA<0.3 wt. %  Formula (2):

0.71≤(Contrast ratio CA)/(Contrast ratio CB)≤0.86   Formula (3):