Krosakiharima Corporation

Kurosaki Refractories Co., Ltd.

Jun Sugawara

Shumei Hosokawa

A cordierite-based sintered body comprises cordierite as a primary crystal phase and LaMgAlOas a secondary crystal phase, wherein a ratio I(114)/I(004) is in the range of 0.01 to 0.8, where the I(114) denotes a peak intensity of a (114) plane of LaMgAlOas measured by powder X-ray diffractometry, and the I(004) denotes a peak intensity of a (004) plane of cordierite as measured by powder X-ray diffractometry. The disclosure is intended to enhance mechanical property and improve complex and fine processability for a cordierite-based sintered body without compromising low thermal expansibility, high dimensional long-term stability, high stiffness (high elastic modulus) and precision polishing characteristic.

Cordierite-based sintered body

The present invention is intended to drastically improve a precision polishing characteristic of a cordierite-based sintered body which has low thermal expansibility, high dimensional long-term stability and high rigidity (high elastic modulus). The cordierite-based sintered body comprises cordierite as primary components, and one or more selected from the group consisting of La, Ce, Sm, Gd, Dy, Er, Yb and Y in an oxide-equivalent amount of 1 to 8 mass %, without any crystal phase other than a cordierite crystal phase. A mass ratio of primary components of the cordierite satisfies the following relations: 3.85&#x2266;SiO/MgO&#x2266;4.60, and 2.50&#x2266;AlO/MgO&#x2266;2.70, and the cordierite-based sintered body after being subjected to precision polishing has a precisely polished surface with an average surface roughness (Ra) of 1 nm or less.

Erosion-resistant silicon carbide composite sintered material, produced from starting materials composed mainly of SiC and also containing ZrB.sub.2 added thereto in an amount up to 50 volume %, resist penetration of, and erosion by, molten metals (such as molten steel) and show high erosion resistance, while retaining the outstanding characteristics unique to silicon carbide, such as high resistance to oxidation, creep and abrasion, and high mechanical strength and impact resistance at high temperatures. Thus the products can be advantageously used as protective pipes for molten metals, crucibles, rollers, nozzles, dies, blow pipes, agitator blades, rotating shafts, inner linings and other structural members which are to be used while in contact with molten metals (particularly molten steel) or other high-temperature metal parts. The corrosion resistance is particularly outstanding when the sintered materials additionally include metallic aluminum or an aluminum compound such as Al.sub.4 C.sub.3, AlN, AlB.sub.2, and Al.sub.2 O.sub.3 in an amount ranging from 5 to 20 vol. % based on the silicon carbide, without detrimentally affecting the mechanical and oxidation resistance properties of the sintered materials.

Growing community of inventors

Fukuoka, Japan

Jun Sugawara