The present invention provides a method that is for producing a zirconia sintered body and by which a zirconia molded body or a zirconia pre-sintered body is sintered in a short period of time, the zirconia sintered body reproducing an aesthetic requirement and strength of an ideal dental prosthesis at the same levels as those of a zirconia sintered body obtained by general firing. The present invention relates to a method for producing a zirconia sintered body, comprising a step of firing a zirconia molded body or a zirconia pre-sintered body, wherein: the firing step comprises at least three temperature increase steps including a first temperature increase step (H1), a second temperature increase step (H2), and a third temperature increase step (H3); a temperature increase rate in the first temperature increase step (H1) is defined as HR1, a temperature increase rate in the second temperature increase step (H2) is defined as HR2, and a temperature increase rate in the third temperature increase step (H3) is defined as HR3; HR1=50 to 500° C./min, HR2=11 to 300° C./min, HR3=10 to 299° C./min, HR1>HR2, and HR2/HR3>1 are satisfied; starting temperatures in the temperature increase steps are room temperature to 500° C. in H1, 900 to 1250° C. in H2, and 1300 to 1550° C. in H3; and reaching temperatures in the temperature increase steps are 900 to 1250° C. in H1, 1300 to 1550° C. in H2, and 1400 to 1650° C. in H3.

A prosthesis that contains zirconia and supplements a defective portion of a natural bone, and that is changed to a color approximate to that of the natural bone by a heat treatment after a γ-ray sterilization treatment. The color approximate to that of the natural bone has an L* value of 60 to 90, an a* value of −5 to 10, and a b* value of −5 to 10 in the L*a*b* color space. The highest temperature in the heat treatment is 100° C. to 300° C. The prosthesis is a fixture of a dental implant embedded into and bonded to a natural bone, an abutment, an implant crown, and the like.

A method of preparing a fine powder of calcium lanthanoid sulfide is disclosed. The method includes spraying soluble calcium and lanthanoid salts into at least one precipitating solution to form a precipitate comprising insoluble calcium and lanthanoid salts, optionally, oxidizing the precipitate comprising insoluble calcium and lanthanoid salts, and sulfurizing the optionally oxidized precipitate to form a fine powder of calcium lanthanoid sulfide. An alternative method for forming the powder is by flame pyrolysis. The calcium lanthanoid sulfide powder produced by either method can have an impurity concentration of less than 100 ppm, a carbon concentration of less than 200 ppm, a BET surface area of at least 50 m.sup.2/g, and an average particle size of less than 100 nm.

The invention relates to a method for the preparation of a blank of a ceramic material, wherein a first ceramic material and then a second ceramic material of different compositions are filled into a die and wherein the materials are pressed and after pressing are sintered. A layer of the first ceramic material is thereby filled into the die and a first cavity formed in the layer, the second ceramic material is then filled into the first open cavity and the materials pressed together and then heat-treated.

The present disclosure relates to a dental ceramic article comprising ceramic components, the ceramic components having ZrO2 and Al2O3 and at least one component comprising Mn, Er or mixtures thereof, Al2O3 being present in an amount below about 0.15 wt.-% with respect to the weight of the ceramic article. The present disclosure relates also to kit of parts comprising a ceramic article and a coloring solution and processes for producing a dental ceramic article.

A silicon nitride ceramic material for a mobile phone rear cover and a preparation method therefor. The method comprises: using a mixture of a silicon source, a colorant, and a sintering aid as raw materials, mixing the raw material components, and performing shaping and sintering to obtain the silicon nitride ceramic material. The toughness of the silicon nitride ceramic material can reach more than 12 MPa.Math.m.sup.1/2; the thermal conductivity thereof can reach 40 to 70 W/m.Math.K; and a dielectric loss thereof is 10.sup.−4.

A complex sintered body includes a lamination of a layer composed of a zirconia sintered body containing 0.5% or more by mole and less than 4% by mole of an oxide of cerium in terms of CeO.sub.2, 2% or more by mole and less than 6% by mole of yttria and 0.1% or more by mass and less than 2% by mass of an oxide of aluminum; and at least one of a layer composed of a zirconia-based sintered body containing 2.0% or more by mass and 20.0% or less by mass of an oxide of aluminum, and a layer composed of a zirconia-based sintered body containing 2% or more by mole and less than 6% by mole of yttria and a coloring agent.

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.

[Problem]

To support the metal without segregation on the zirconia mill blank for dental cutting and machining which has been adjusted to a hardness that enables to cut and machine by calcining at a low temperature.

[Solution]

A zirconia mill blank for dental cutting and machining is prepared by A preparing method of a zirconia mill blank for dental cutting and machining, comprising an impregnation step of impregnating a porous zirconia molded body with an impregnating solution containing at least one metal ion and at least one precipitant, and a deposition step of decomposing the precipitant in the porous zirconia molded body to deposit a metal compound.

One aspect relates to a process for producing a sintered workpiece, which includes sintering of a ceramic material at a temperature of at least 1000° C. and in an atmosphere, in the case of which the partial pressure of atmospheric air is reduced to less than 10.sup.−6-times, based on the ambient air at the same temperature under equilibrium conditions.