再結晶炭化ケイ素：要求の厳しい用途に適した高性能材料

Recrystallized Silicon Carbide (RSiC) is a high-performance ceramic material with excellent mechanical, thermal, and electrical properties. Its unique combination of properties makes it an ideal material for demanding applications in various industries, including aerospace, semiconductor, and automotive. In this article, we will explore the properties of RSiC, its manufacturing process, and its applications in various industries.

Properties of Recrystallized Silicon Carbide
RSiC is a ceramic material consisting of silicon and carbon atoms in a crystal lattice structure. It is formed by recrystallizing silicon carbide powder at high temperatures (>2200°C) in a vacuum or inert atmosphere. The resulting material has a density of 2.6 g/cm³, a porosity of less than 1%, and a high degree of purity (>99.5%).

Mechanical Properties:
RSiC has excellent mechanical properties, including high strength, toughness, and hardness. Its Young’s modulus is approximately 400 GPa, which is higher than that of steel, and its fracture toughness is around 4.5 MPa.m^0.5, which is superior to that of most ceramics. Its hardness is around 2400 Vickers, which makes it one of the hardest known ceramics.

Thermal Properties:
RSiC has outstanding thermal properties, including high thermal conductivity, low thermal expansion, and excellent thermal shock resistance. Its thermal conductivity is around 100-150 W/m.K, which is higher than that of most ceramics and comparable to that of metals. Its coefficient of thermal expansion is about 4.5 x 10^-6/K, which is low compared to that of other ceramics. Its thermal shock resistance is attributed to its high thermal conductivity and low thermal expansion.

Electrical Properties:
RSiC has good electrical properties, including high electrical resistivity and low dielectric loss. Its electrical resistivity is around 5 x 10^6 Ω.cm at room temperature, which makes it an excellent insulating material. Its dielectric loss is less than 0.01 at frequencies up to 1 MHz, which makes it suitable for high-frequency applications.

Manufacturing Process of Recrystallized Silicon Carbide:
The manufacturing process of RSiC involves several steps, including:

Fabrication of the green body: Silicon carbide powder is mixed with a binder and formed into a green body by uniaxial or isostatic pressing.

Pre-sintering: The green body is pre-sintered at a temperature of around 1650°C to give it sufficient strength and rigidity for handling.

Shaping: The pre-sintered green body is machined to the desired shape using various techniques, such as cutting, grinding, and milling.

Final sintering: The machined green body is heated to a temperature of > 2200°C in a vacuum or inert atmosphere to recrystallize the silicon carbide powder, resulting in a dense and pure RSiC material.

Applications of Recrystallized Silicon Carbide:
RSiC has a wide range of applications in various industries, including:

Aerospace: RSiC is used as a lightweight and high-strength material in aerospace structures, such as turbine blades, rocket nozzles, and heat shields.

Semiconductor: RSiC is used as a crucible material for the production of silicon wafers, and as a substrate material for the growth of gallium nitride (GaN) films.

Automotive: RSiC is used as a brake disc material due to its high thermal conductivity and low thermal expansion.

Chemical: RSiC is used as a lining material in high-temperature furnaces and reactors in the chemical industry.

Conclusion:
Recrystallized Silicon Carbide is a high-performance ceramic material with excellent mechanical, thermal, and electrical properties. Its unique combination of properties makes it an ideal material for demanding applications in various industries, including aerospace, semiconductor, and automotive. Its manufacturing process involves several steps, including green body fabrication, pre-sintering, shaping, and final sintering. Overall, RSiC is a versatile material that has the potential to revolutionize various industries and pave the way for new technologies.