The present invention relates to a kit of parts comprising a dental mill blank comprising a porous zirconia material and a colouring solution for colouring the porous zirconia material. The porous zirconia material comprises Zr oxide calculated as ZrO2: from 80 to 97 wt.-%, Al oxide calculated as Al2O3: from 0 to 0.15 wt.-%, Y oxide calculated as Y2O3: from 1 to 10 wt.-%, Bi oxide calculated as Bi2O3: from 0.01 to 0.2 wt.-%, the porous zirconia material not comprising Fe calculated as Fe2O3 in an amount of more than 0.01 wt.-%, wt.-% with respect to the weight of the porous zirconia material. The colouring solution comprises solvent(s), colouring agent(s) comprising metal ions selected from Tb, Er, Pr, Mn or combinations thereof, the solution not comprising Fe ions in an amount of more than 0.01 wt.-%, the solution not comprising Bi ions in an amount of more than 0.01 wt.-%, wt.-% with respect to the weight of the colouring solution. The invention also relates to a process of producing a dental restoration, the process comprising the steps: providing a dental mill blank comprising a porous zirconia material as described in any of the preceding claims, machining an article out of the porous zirconia material, the article having the shape of a dental restoration with an outer and inner surface, providing a colouring solution as described in any of the preceding claims, applying the colouring solution to at least portions of the surface of the article having the shape of a dental restoration.

The present invention discloses a method for uniformly coating metal nanoparticles without a carbon impurity on an oxide ceramic powder surface, which includes the steps of putting grinded and mixed a metal organic material and oxide ceramic powder into a rotational reaction chamber, then bubbling oxidizing gas under a rotational and heating condition to oxidize the metal organic material into a metal oxide, and finally bubbling reducing gas to reduce the metal oxide into nanoparticles in a metallic state, so as to implement the uniform coating of the nanoparticles in the metallic state, and avoid coarsening and growing problems of nanoparticles led by a long-term coating reaction under a high temperature. The present invention has a simple method and a short preparation period, and the metal nanoparticles prepared are uniformly dispersed and have wide application prospects in multiple fields like catalytic materials and conductive ceramics.

A method of producing a boron nitride polycrystal includes: a first step of obtaining a thermally treated powder by thermally treating a powder of a high pressure phase boron nitride at more than or equal to 1300° C.; and a second step of obtaining a boron nitride polycrystal by sintering the thermally treated powder under a condition of 8 to 20 GPa and 1200 to 2300° C.

A cubic boron nitride sintered material includes: more than or equal to 50 volume % and less than 80 volume % of cubic boron nitride grains; and more than 20 volume % and less than or equal to 50 volume % of a binder phase, and when an oxygen content is measured in a direction perpendicular to an interface between cubic boron nitride grains using TEM-EDX, a first region having an oxygen content larger than an average value of an oxygen content of a cubic boron nitride grain exists, the interface exists in the first region, and a length of the first region along the direction perpendicular to the interface is more than or equal to 0.1 nm and less than or equal to 10 nm.

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 method of making a polycrystalline cubic boron nitride (PCBN), material is provided. The matrix precursor powder comprises an aluminium compound. The method comprises mixing matrix precursor powder comprising particles having an average particle size no greater than 250 nm, with between 30 and 40 volume percent of cubic boron nitride (cBN) particles having an average particle size of at least 4 μm, and then spark plasma sintering the mixed particles. The spark plasma sintering occurs at a pressure of at least 500 MPa, a temperature of no less than 1050° C. and no more than 1500° C. and a time of no less than 1 minute and no more than 3 minutes.

The invention relates to a coloured zirconia ceramic dental mill blank having fluorescing properties, processes of production such a mill blank and uses thereof, in particular for producing zirconia ceramic dental restorations.

The dental mill blank having a shape allowing the dental mill blank to be attached or fixed to a machining device, the dental mill blank comprising a porous zirconia material, the porous zirconia material comprising the oxides Zr oxide calculated as ZrO.sub.2: from about 80 to about 97 wt.-%, Al oxide calculated as Al.sub.2O.sub.3: from about 0 to about 0.15 wt.-%, Y oxide calculated as Y.sub.2O.sub.3: from about 1 to about 10 wt.-%, Bi oxide calculated as Bi.sub.2O.sub.3: from about 0.01 to about 0.20 wt.-%, Tb oxide calculated as Tb.sub.2O.sub.3: from about 0.01 to about 0.8 wt.-%, and optionally one or two of the following oxides: Er oxide calculated as Er.sub.2O.sub.3: from about 0.01 to about 3.0 wt.-%, Mn oxide calculated as MnO.sub.2: from about 0.0001 to about 0.08 wt.-%, wt.-% with respect to the weight of the porous zirconia material.

An object of the present invention is to provide zirconium oxide nanoparticles that have excellent dispersibility in a polar solvent and are capable of increasing a core concentration in a dispersion liquid. Zirconium oxide nanoparticles according to the present invention are coated with at least one compound selected from the group consisting of R.sup.1—COOH, (R.sup.1O).sub.3-n—P(O)—(OH).sub.n, (R.sup.1).sub.3-n—P(O)—(OH).sub.n, (R.sup.1O)—S(O)(O)—(OH), R.sup.1—S(O)(O)—(OH), and (R.sup.1).sub.4-m—Si(R.sup.4).sub.m, wherein R.sup.1 represents a group comprising a carbon atom and at least one element selected from the group consisting of an oxygen atom, a nitrogen atom, and a sulfur atom, and having the total number of carbon atoms, oxygen atoms, nitrogen atoms, and sulfur atoms of 8 or less; R.sup.4 represents a halogen atom or —OR.sup.2, and R.sup.2 represents a hydrogen atom or an alkyl group; and n represents 1 or 2, and m represents an integer of 1 to 3.

Provided are metal oxide ceramic materials and intermediate materials thereof (e.g., nanozirconia gels, nanozirconia green bodies, pre-sintered ceramic bodies, zirconia dental ceramic materials, and dental articles). The nanozirconia gels are formable gels. Also provided are methods of making and using the metal oxide materials and intermediate materials. The nanozirconia gels can be made using, for example, osmotic processing. The nanozirconia gels can be used to make nanozirconia green bodies, pre-sintered ceramic bodies, zirconia dental ceramic materials, and dental article. The nanozirconia green bodies, pre-sintered ceramic bodies, zirconia dental ceramic materials, and dental articles have desirable properties (e.g., optical properties and mechanical properties).

A polycrystalline cubic boron nitride comprising 98.5% by volume or more of cubic boron nitride, wherein the cubic boron nitride has a dislocation density of more than 8×10.sup.15/m.sup.2, the polycrystalline cubic boron nitride comprises a plurality of crystal grains, and the plurality of crystal grains have a median diameter d50 of an equivalent circle diameter of 0.1 μm or more and 0.5 μm or less.