Provided is an aluminum nitride powder useful as a raw material when an aluminum nitride sintered body excellent as an insulating high thermal conductive member is manufactured, particularly, by press molding.

An aluminum nitride powder includes particles having a sphericity of 0.8 or more, in which a median size D.sub.50 obtained by a laser diffraction method is 0.5 to 1.5 μm, a ratio D.sub.90/D.sub.50 of a particle size D.sub.90 corresponding to a cumulative undersize distribution of 90% to the D.sub.50 is 2.2 or less, a BET specific surface area is 2 to 4 m.sup.2/g, and a total oxygen concentration is 0.6 to 1.2% by mass.

A Cr—Si sintered body contains Cr and Si. The Cr—Si sintered body contains a crystalline CrSi.sub.2 phase and a crystalline Si phase. A content of the Si phase in the Cr—Si sintered body is 40% by mass or more. A relative density of the Cr—Si sintered body relative to a true density of the Cr—Si sintered body is 95% or more. The CrSi.sub.2 phase has an average crystal grain size of 40 μm or less, and the Si phase has an average crystal grain size of 30 μm or less. A total content of impurities in the Cr—Si sintered body is 200 ppm by mass or less, and the impurities are composed of at least one element selected from the group consisting of Mn, Fe, Mg, Ca, Sr, and Ba.

A member for optical glass production apparatus is a member exposed to a gas containing a halogen element in a high temperature environment; the member includes a first member (4) directly or indirectly supporting an optical glass (10) and a second member (5) supporting the first member (4).

Disclosed are a silicon carbide powder, a method of manufacturing a silicon carbide powder, and a silicon carbide wafer. More particularly, the silicon carbide powder includes carbon and silicon and in the silicon carbide powder, O1s/C1s of a surface measured by X-ray photoelectron spectroscopy is 0.28 or less.

A method for manufacturing a silicon carbide powder according to the embodiment includes forming a mixture by mixing a silicon (Si) source containing silicon with a solid carbon (C) source or a C source containing an organic carbon compound; heating the mixture; cooling the mixture; and supplying hydrogen gas into the mixture.

A particle mixture having: ZrO.sub.2+HfO.sub.2+Y.sub.2O.sub.3+CeO.sub.2; 0%≤Al.sub.2O.sub.3≤1.5%; other oxides than ZrO.sub.2, HfO.sub.2, Y.sub.2O.sub.3, CeO.sub.2 and Al.sub.2O.sub.3: between 0.5% and 12%. The contents of Y.sub.2O.sub.3 and CeO.sub.2, on the basis of the sum of ZrO.sub.2, HfO.sub.2, Y.sub.2O.sub.3 and CeO.sub.2, being such that 1.8%≤Y.sub.2O.sub.3≤3% and 0.1%≤CeO.sub.2≤0.9%. The mixture includes between 0.5% and 10% of particles of an oxide pigment. The content of other oxides and which are not included in the oxide pigment being less than 2%. The particles of the oxide pigment including, for more than 95%, of a material chosen from: oxide(s) of perovskite structure or equivalent of precursor(s) of these oxides, oxides of spinal structure or an equivalent amount of precursor(s) of these oxides, and oxides of hematite structure E.sub.2O.sub.3, oxides of rutile structure FO.sub.2, with “E” and “F” being chosen.

A cubic boron nitride-based sintered material includes cubic boron nitride particles of 70 to 95 vol %, in which in a structure of a cross-section of the sintered material, a binder phase with a width of 1 nm to 30 nm is present between the adjacent cubic boron nitride particles, the binder phase being made of a compound containing at least Al, B, and N and having a ratio of an oxygen content to an Al content of 0.1 or less in terms of atomic ratio.

The purpose of the present is to provide a modified AlN source for suppressing downfall defects. This manufacturing method of a modified aluminum nitride source involves a heat treatment step for heat treating an aluminum nitride source and generating an aluminum nitride sintered body.

A sintered material is provided having a phase of a compound at least containing a rare earth element and fluorine, the sintered material having an L* value of 70 or more in the L*a*b* color space. The crystal grains of the sintered material preferably has an average grain size of 10 μm or less. The sintered material preferably has a relative density of 95% or more. The sintered material preferably has a three-point flexural strength of 100 MPa or more. The sintered material preferably contains no oxygen, or preferably has an oxygen content of 13% by mass or less when containing oxygen. The compound is preferably rare earth element fluoride or oxyfluoride.

Disclosed are methods for producing carbon foam in which using the vitrinite reflectance values of coals are used to form a blended coal precursor having a targeted vitrinite reflectance value. The targeted vitrinite reflectance value can be used to create similar carbon foam products from one production batch to the next.