Black ceramic sinter with low thermal expansion and high specific rigidity and process for producing the same

A black low thermal expansion high specific rigidity ceramic sintered body, comprising:

• having a thermal expansion coefficient of not more than 0.6×10−6/° C. in absolute value at room temperature,
• a modulus of elasticity (Young's modulus) of not less than 100 GPa,
• a specific rigidity (Young's modulus/specific gravity) of not less than 40 GPa·cm3/g, and
• assuming a black tone.

A black low thermal expansion high specific rigidity ceramic sintered body, comprising:

• having a thermal expansion coefficient of not more than 0.6×10−6/° C. in absolute value at room temperature,
• a modulus of elasticity (Young's modulus) of not less than 100 GPa,
• a specific rigidity (Young's modulus/specific gravity) of not less than 40 GPa·cm3/g, and
• assuming a black tone,
• said black low thermal expansion high specific rigidity ceramic sintered body having a chemical composition comprising:
• 8.0–17.2 mass % of MgO,
• 22.0–38.0 mass % of Al2O3,
• 49.5–65.0 mass % of SiO2,
• a total of 0.1–2 mass % of one or more transition elements as reduced to oxides,
• 0–2.5 mass % of Li2O, and
• having the mass ratios satisfy the relationships of (SiO2−8×Li2O)/MgO≧3.0 and (SiO2−8×Li2O)/Al2O3≧1.2.